EPA-450/Z-77-008

May 1977

(OAQPS NO. 1.2-073)

CAN COATING

AP-42

Section 4.2.2.1

Reference Number

3\

U.S. ENVIRONMENTAL PROTECTION AGENCY

Office of Air and Waste Management

OAQPS GUIDELINES

CONTROL OF VOLATILE

ORGANIC EMISSIONS

FROM- EXISTING t

STATIONARY SOURCES -

VOLUME II: SURFACE COATING

2” ;, .r I OF CANS, COILS, PAPER,

Office of Air Quality Planning and Standards

Research Triangle Park, North Carolina 27711

I

3
EPA-450/Z-77-008

(OAQPS NO. 1.2-073)

CONTROL OF VOLATILE

ORGANIC EMISSIONS FROM EXISTING

STATIONARY SOURCES - VOLUME II:

SURFACE COATING OF CANS, COILS,

PAPER, FABRICS, AUTOMOBILES,

AND LIGHT-DUTY TRUCKS
This report is issued by the Environmental Protection Agency to report

technical data of interest to a limited number of readers. Copies are

available free of charge to Federal emplayees, current contractors and

grantees, and nonprofit organizations - in limited quantities - from the

Library Services Office (MD-35) , Reseaxh Triangle Park, North Carolina

27711.

Publication No L EPA-450/2-77-008

ii
PREFACE

This is the second in a series of reports designed to assist State

and local jurisdictions in the development of air pollution control

regulations for surface coating industries. These reports are directed

entirely at the control of volatile organic compounds (WC) which contribute to the formation of photochemical oxidants. Volume I provides

very general information on the cost and effectiveness of control

technology and guidelines for sampling and analyzing VOC emissions.

Volume II provides specific information on air pollution control of

five surface coating industries; namely, automobile and light duty truck,

can, coil, fabric and paper coating operations. For each industry,

coating systems are reviewed and various VOC control alternatives are

considered together with their costs and limitations. This volume also

provides guidance on the preparation of air pollution control regIplations

and test methodology suitable for their enforcement (Appendices A and C).

It must be cautioned that the limits provided below are based 0;:

capabilities and characteristics which are general and therefore presumed

normal to these industries; the limits may not be applicable to every plant

within an industry. For example, although the level of control recommended

for the can industry is based on coatings that are generally available, those

coatings may not be suitable for every product manufactured by a can plant.

In each case the recommended limitation is stated in terms of solvent

content of the coating. This form is most applicable to situations where low

solvent coatings are employed. If an operator should choose to comply by

iii
installation of add-on control devices, it may be appropriate for the agency

to set minimal requirements on the hooding or capture system and the

efffc~encv of the control device,

The tables that follow provide &ssion 'Ilmifations that represent

the presumptive norm that can be achieved through the application of

reasonably avaflable control technolqjy (RACT). Reasonably avajlable

control technology ia defjned as the lowest emldision 14mlt that a particular source is capable of meeting by the application of control technology

that is reasonably available considerfng technologjcal and economic feasibility.

It may require technology that has been applied to simjlar, but not necessarily

Uentical, source categories. It is not intended that extensive research and

development be conducted before a given control technology can be applied

to the source. Th9s does not+ however, preclude requiring a short-term

evaluation program to permit the application of a given technology to a

particular source. This latter effort is an appropriate technology-forcing

aspect of RACT.

CAN INDUSTRY

Affected Facility

Sheet basecoat (exterior

and interior) and overvarnish; two-piece can

exterior (basecoat and

overvarnish)

Two and three-piece can interior

body spray, two-piece can

exterior end (spray or roll

coat)

Three-piece can side-seam spray

End sealing compound

Recommended Limitation

kg per liter lbs per gal

of coating of coating

Jminus water) (minus water)

0.34 2.8

0.51 4.2

0.66

0.44

5.5

3.7
The limitation for the sheet basecoat (exterior and interior) and

overvarnish; two-piece can exterior (basecoat and overvarnish) assumes

the average solids content of all coatings is about 25 volume percent

and the solvent is an 80 percent water, 20 percent organic mixture.

The organic-borne equivalent is 64 volume percent solids. Such coatings

are now used by some companies on part of their Production.

The limitation for two and three-piece can interior body spray,

two-piece can exterior end (spray or roll coat) oresumes all coatings

average 18 volume percent solids in an TO:30 water to organic solvent

ratio. Such coatings are now used on some beer and beverage cans.

The limitations for the three-piece can side-seam spray assumes an

increase in the solids content of typical present-day coatings by 100

percent to 25 volume percent. Water-borne coatings for some unique

products have been developed that are aoplied at solvent contents as low

as 0.53 kilograms per liter of coating.

The limitation on end sealing compound emissions presumes an increase

in the solids content of a typical organic-borne coating from 30 to 50

percent. Water-borne coatings for some unique products are applied at

solvent contents as low as 0.26 kilograms per liter of coating.

COIL COATING INDUSTRY

Affected Facility Recommended Limitation

kg per liter lbs per gal

of coating of coating

(minus water) (minus water)

Prime and topcoat or single 9.31 2.6

coat operatfon
This limitation is based on incineration of the emissions from an

organic-borne coating which contains 25 volume percent solids. To comply,

90 percent of the solvent in the coating would have to be captured and

directed to the control device (afterburner) which must be at least 90

percent efficient. There are also some water-borne coatings that will

comply with this level of control without the need for add-on control

equioment.

FABRIC COATING

Affected Facility

Fabric coating l.ine

Vinyl coating line

Recxnmnended Limitation

kg per liter lbs per gal

of coating of coating

Jminus water) (minus water)

0.35 2.9

0.45 3.8

"Fabric coating" 'includes alJ types of coatings applied to fabric,

a large portion of which is rubber used for rainwear, tents and industrial

purposes such as gaskets and diaphrams. "Vinyl coatinq" refers to any

printing or decorative or protective topcoat applied over vinyl coated

fabric or vinyl sheets. It does not include the application of vinyl

olastisol to the fabric (emissions from the application of plastisol are

near zero).

The limitations for both are based on use of an add-on control device

which recovers or destroys 81 percent of the VOC introduced in the coating.

Typically, this will require that 90 percent of the \iOC is captured and

delivered to the control device which also must have an efficiency of 90

percent.

v i
The limitation for fabric coating could also be achieved by use of

an organic-borne coating which is about 60 volume percent solids or a

water-borne 80:20 coating with a solids content of about 24 volume percent.

Neither of these coatings are known to be in routine use by the industry.

PAPER COATING

Affected Facility Recommended Limitation

kg per liter‘ lbs per gal

of coating of coating

(minus water) (minus water)

Coating line 0.35 2.9

These levels are for all coatings put on paper, pressure sensitive

tapes regardless of substrate (including oaper, fabric or plastic film)

and related web coating processes on plastic film such as typewriter

ribbons, photographic film, and magnetic tape. Also included are decorative

coatings on metal foil such as gift wrap and packaging. These limits can

be achieved in all cases using incineration and in many cases with coatings

that contain low fractions of organic solvents.

AUTOMOTIVE AND LIGHT DUTY TRUCK ASSEMBLY PLANTS

Affected Facility

Prime application, flashoff

area and oven

Topcoat application, flashoff

area and oven

Final repair application,

flashoff area and oven

Recommended Limitation

kg per liter lbs per gal

of coating

(minus water)

of coating

(minus water)

0. 23 1.9

0.34 2.8

0.58 4.8
These limits apply to all objects surface coated in the plant including

the body, fenders, chassis, small parts, wheels, sound deadners, etc. It

does not apply to adhesives.

The level recorrmended for prime application is based on use of an

electrophoretic system followed by a 25 percent solids water-bone "surfacer"

to build thickness and improve the adhesion of the topcoat. Water-borne

surfacer is in use at trio U.S. plants. The electrophoretic system is now in

use at about half of the plants in the United States. Although several of

these were converted to electrophoretic, such a transition may not be reasonable

for an existing assembly line which uses a water-borne dip prime coating system

releasing about 0.38 kilograms per liter of coating. The moderate reduction

in emissions possible with electrophoretic coatings would be obtained at

great expense.

The level for topcoat represents a water-borne coating now in use by

two plants in the United States. Because of: (1) the large expenditures

required to convert from organic-borne coatings to water-borne coating, it may

be reasonable to grant some finite period for a source to develop low

solvent organic-borne coatings with equivalent emission characteristics.

The level for "final repair" is based on use of an organic-borne

enamel with 35 percent solids. Water-borne coatings cannot be employed

for the assembled automobile. None of the automakers are using coatings of

35 percent s &lids at present but such use is now scheduled at one U.S. plant.

viii
TABLE OF CONTENTS

VOLUME II, SURFACE COATING.OF CANS, COILS, PAPER, FABRICS, AUTOMOBILES,

AND LIGHT-DUTY TRUCKS

PREFACE .................................

1,O INTRODUCTION ............................

2.0 CAN COATING ............................

2.1 Summary of Control Technology .................

2.2 General Discussion ......................

2.2.1 Materials Used .....................

2.2.2 Processes and Affected Facilities. ...........

2.3 Special Considerations ....................

2.4 Available Control Technology. .................

2.4.1 Option 1 - Incineration ................

2.4.2 Option 2 - Water-Borne/High-Solids!Powder Coatings ...

2.4.3 Control Option 3 - Carbon Adsorption Coating ......

2.4.4 Control Option 4 - Ultraviolet Curing. .........

2.5 Comparison of Control Options and Conclusions .........

3.0 COIL COATING ............................

3.1 Sumnary of Control Technology .................

3.2 -General Discussion .......................

3.2.1 Materials Used .....................

3.2.2 Processes and Affected Facilities. ...........

3.3 Special Considerations. ....................

3.4 Available Control Technology. .................

3.4.1 Option 1 - Incineration ................

3.4.2 Option 2 - Water-Borne and High-Solids Coating .....

3 ." Comparison of Control Options and Conclusions .........

i

l-l

2-l

2-l

2-2

2-4

2-6

2-13

2-17

2-17

2-25

2-28

2-32

2-34

3-l

3-l

3-l

3-3

3-4

3-8

3-11

3-12

3-21

3-25
4.0 FABRIC COATING. ......................... 4-l

4.1 Sumary of Control Technology ................ 4-l

4.2 General Discussion ..................... Q.-l

4.2.1 Materials Lised .................... 4-2

4.2.2 Processes and Affected Facilities .......... 4-2

4.3 5pecial Considerations. ................... 4-11

4.4 Avai 1 able Con trsl Technol ogy ................. 4-12

4.4.1 Option 1 - Incineration ............... 4-12

4.4.2 Option 2 - Carbon Adsowtim ............. 4-15

4.4.3 option 3 - tow Qrgank Solvent Coathgs ....... 4-18

4.5 Comparison of Control Options and Conclusions ........ 4-18

5.0 PAPER COATING.. ..........................

5.1 Summary of Control Technology ................

5.2 Geaeral Discussion. .....................

5.2.1 Materials Used ....................

5.2.2 Processes and Affected Facility ...........

5.3 Special Considerations. ...................

5.4 Available Control Technology. ................

5.4.1 Option 1 - Low Solvent Coatings. ...........

5.4.2 Option 2 - Incineration. ...............

5.4.3 Option 3 - Carbon Adsorption .............

5.5 Comparison of Control Options and Conclusions ........

5-l

5-l

5-l

5-4

5-8

5-14

5-14

5-14

5-21

5-23

5-27

6.0 AUTOMOBILE AND LIGHT DUTY TRUCK ASSEMBLY ............. 6-l

6.1 Sumnary of Control Technology ................ 6-l

6.2 Qneral Discussion. ................... . . 6-2
6.2.1 Haterials Used . . . . . . . . . . . . . . . . . . . 6-6

6.2.2 Processes and Affected Facilities. . . . . . . . . . 6-7

6.3 Special Considerations. . . . . . . . . . . . . . . . . . . 6-10

6.4 Available Control Techn010gy. . . . . . . . . . . . . . . . 6-14

6.4.1 Option 1 --Electr0de~sition of Water-Borne Primer . 6-17

6.4.2 Option 2 - Lower Solvent Primer and Topcoat. . . . . 5-22

6.4.3 Option 3 - Carbun Adsmptiun fur Primer and Topcoat

spMy5uQths . . . . . . . . . . . . . 6-24

6.4.4 Option 4 - 'Incineration for Spray Booths . . . . . . 6-29

6.4.5 Option 5 - Incineration for h-her and Toptsat

m?ns.....* l . . . . . . . . . . 6-31

6.4.6 Option 6 - Water-Borne Topcoats . . ., . . . . . . . 6-36

6.5 Comparison of Control Options and Conclusions . . . . . . . 6-41

W'ENDTX A - ANALYTICAL TECHNIQUES . . . . . . . . . . . . . . . . . A-l

APPENDIX B - RECOMMENDED POLICY ON CONTROL OF

VOLATILE ORGANIC COMPOUNDS . . . . . . . . . . . . . . B-1

.

APPENDIX C - REGULATORY GUIDANCE. .................. C-l

APPENDIX D,- CONVERSION METHODS ................... D-l

x i
1.0 INTRODUCTION

The industries reviewed herein represent some of the largest and most

widespread sources of volatile organic solvents in the nation. Moreover,

their products, often with very specialized surface coatings, are interwoven

into many facets of our economy and are subject to a wide range of performance

demands. Collectively, they release about 850,000 tons of VOC annually to the

atmosphere with the largest individual sources each being responsible for

over 1,000 tons per year. The five industries employ a variety of coating

application and curing techniques, all of which impact on the viability of

alternative VOC control technologies. From the air pollution control standpoint, it is immaterial whether VOC are removed from the coating process or

are controlled at the point of emission. Nonetheless, since solvent recovery

and/or elimination strongly influence control costs and acceptance by the

affected industries, much of this document is directed at the review of

alternative control strategies, costs, and energy impacts.

To varying degrees, four different abatement methods have been used

to reduce the contribution of surface coating VOC to the photochemical

oxidant burden. These are:

(i) "Add-on" technology I 0 destroy or recover VOC from

exhaust gases,

(2) Reformulation of coatings to minimize organic

solvent content,

( ') Modification of the process to rc:.'~ce the quantity

of VOC which escapes from a coating l-, I, and

l-l
(4) Substitution of less photochemically reactive solvents

in surface coating formulations.

The first three are "positive reduction" techniques in that they

actually reduce the mass of VOC released to the atmosphere. The fourth,

solvent substitution, doesn't reduce the quantity of organic emissions

and has been only marginally effective In reducing amblent concentrations

of photochenical ox+drnts (see Appendix 8). In preparing this document,

arincipal attentian has been directed at add-on control technology and

the reformulation of coatings. These two positive reduction techniques

cumhtly affer greeter potential for reducing organic missions than

process modifications far the five surface coating operations in question.

In previous years the primary method used to reduce organic emissions

from stationary sources has been through stack gas treatment, prjmarfly

incineration. Incinerators or afterburners have evolved as the basic

control technique to which the efficiency of alternative methods is

often compared. Within the coating industry, however, incinerators

have, for the most part, been limited to baking and curing ovens. In

rest instances, spray coating operations, which are much larger sources

of VOC than associated ovens, have gone uncontrolled. It is for these

coating sources that low-solvent coatings offer the greatest promise.

l.1 LOW-SOLVENT COATINGS

Coatings which contain relatively low fractions of organic.solvent,

the so-called "low-solvent coatings" (water-borne, high-solids, and

powder coatings), offer the advantage of saving valuable petroleum

feedstocks while also eliminating the need for abatement equipment and

its concomitant requirement for fuel and power.

The desirability of low-solvent coatings was recognized and acknowledged

by the Los Angeles County Air Pollution Control District in 1971 when

l-2
incentives were added to Rule 66--its regulation governing use of

solvents. Under Rule 66, operators are not required to incinerate

oven exhaust gases if the surface coating meets specified limitations

(less than 20 percent organic solvent in coating by volume or an organic

solvent-to-water ratio of 20:80 or less in water-borne coatings). Many

other governmental agencies throughout the nation have adopted similar

incentives.

The low-solvent coating provisions of Rule 66 were developed at a

time when few water-borne, high-solids, or powder coatings were available.

In the six years since these incentives were first offered to the industry,

there has been only a limited shift in that direction. Currently, they

represent only about 10 percent of industrial surface coating sales. The

rest are conventional organic-borne formulations with an organic solvent

content of 60 to 90 percent or more. Lack of greater acceptance of lowsolvent coatings by the industry is attributable to many factors, some

of which are: difficulties in achieving Rule 66 specifications, relatively

low cost of solvents, and the ability to comply with air pollution ,regulations

by less burdensome means such as solvent substitution.

The dramatic reduction which can be achieved in switching to lo+solvent

coatings is often not apparent from coating specifications. For example,

with the aid of Figure 1, it can be shown that an operator now using a 30

volume percent solids (70 percent organic solvent) coating could reduce his

VOC emissions 57 percent by rep cement with a coating containing 59 percent

sol,il;s. If he could use a coating of 70 percent solids, his VOC reduction

would be 82 percent. Even greater reductions can be realized by users of

highly -,ilute coatings such as lacquers. Ai. ?nerator now using a 10 volume

percen' solids lacquer could effect a; 88 *cent VCC reduction by switching

to ? 50 lercent solids enamel. By switchir., to a 70 percent solids coating,

l-3
Prrcent Emission Reduction Per Volume of Solids Aoolled (Item Coated) lb. solvent/aallon of coatinq (less water)

(p = 7.36 #/Ml)

/

L
his VOC reduction would be 95 percent. Conversion to water-borne coatings

will also significantly reduce VOC emissions. Replacement of a 30 volume

percent solids organic-borne coating with an 8O:ZO water-borne (80 percent

water, 20 percent organics,1 of similar solids content would yield a VOC

reduction of about 80 percent for a given industrial application.

1.2 STACK GAS TREATMENT

Founding emission limitations on low-solvent technology is not without

its drawbacks. In some instances, switching to low-solvent coatings may

not provide as much VOC control as would add-on control devices. This could

be true during any transition period as we phase into lower solvent coatings.

For certain industries, it will be more effective and possibly less costly

to employ incineration, adsorption, or other techniques to remove or destroy

VOC in the exhaust gases. Carbon adsorption should continue to find use

where the solvent has a relatively high market value and is amenable to

recovery with adsorption techniques. Incineration is expected to remain

a viable alternative where organic concentrations can be maintainei at

relatively high levels such that auxiliary fuel requirements are no-, excessive

or where energy in the hot exhaust gases can be recovered and used tc offset

fuel requirements elsewhere in the plant.

A major disincentive to applying stack gas treatment to VOC sources is

the low concentration of organics often encountered. These low concentrations

mean large volumes of air or other diluents must be processed to control the

solvent. This results' in higher costs and energy requirements for control

equipment and, frequently, lower control efficiencies. Major reasons for

such low concentrations are: (1) solvents are toxic to the worker, hence,

are intentionally diluted below the thresltold limit value (TLV); (2) concentrations are maintained well below the loo- explosive limit (LEL) to reduce

l-5
“I ’ the risk of fire or explosion; (3) large alrutlon rmius 01~ tbcbt23~~~ bw

accomnodate fluctuations in VOC evaporation rates, and (4) the operator is

unaware of the multiple benefits of minimizing the intrusion of diluent air.

The greatest dilution and lowest VOC levels are found in hand-held

spraying operations and are attributable to TLV restrictions. No large

worker-occupied spray booths such as those used in auto assembly plants

have been controlled with VOC stack gas treatment technology. Where the

coating is applied mechanically as with a knife, roller, or electrostatic

spray gun, it is usually possible to maintain much greater VOC concentrations

in exhaust gases. Similarly, baking and curing ovens can be maintained at

VOC levels much greater than are feasible for worker-occupied spray booths.

Solvent concentrations in ovens and automated coating applications are

generally maintained below 25 percent LEL because of safety hazards associated

with higher concentrations.' Unfortunately, many ovens are operated at

organic concentrations well below this level. For example, at 5 percent LEL,

the exhaust rate is five-fold greater than at 25 percent LEL and any add-on

control device must be five times larger. In many cases , such low concentrations are not necessary. Changes in system design and operating practices

can minimize air intrusion with the attendant benefit of a reduced exhaust

volume and reduced control costs.

In a few industries, operators have been notably successful in

maintaining VOC levels at greater than 25 percent LEL and effecting

major fuel economies. For example, several coil coaters have actually

reduced fuel consumption in the coating oven by use of incineration

devices and heat exchangers and maintaining VOC concentrations at 30 to

40 percent LEL. In many more applications, incineration would be a more

cost effective control option if air intrusion were minimized and VOC

levels held to 25 percent LEL or greater. This ancillary aspect of VOC

control has received only limited attention in many industries.

'Some insurers will permit operation up to 50 percent of the LEL if

appropriate monitoring and fail-safe relief systems are installed.

l-6
1.3 EMISSION LIMITATIONS

Historically, VOC control regulations have included limitations on the

organic solvent of coatings or have stipulated that a certain percent reduction

be achieved through stack gas treatment. While either approach is acceptable

if limits are appropriate, solvent content is a more reasonable basis for

surface coating operations which are expected to employ low-solvent coatings.

For these five industries, it is recommended that emission limitations

be expressed in terms of organic solvent content since these values can be

determined with relati V ely simple analytical techniques and are directly

relatable to VOC erniss i ons. For operators who use stack gas treatment,

alternative compliance procedures should be included.

Solvent content 1 i mitations may be expressed in terms of mass or

volume and may be based on the entire coating (including solvent) or only on

paint solids. In this document, limitations are expressed as the allowable

mass of VOC per unit volume of coating (kg per liter or lb per gallon) as it

is applied to the product. The principal advantage of this format i- that

enforcement is relatively simple. Field personnel can draw samples dnd have

them analyzed quickly. A disadvantage is that the relationship between the

solvent fraction and VOC emissions is not linear. As illustrated in

Figure D-Z of Appendix 0, use of a coating containing 3 lbs of VOC per

gallon of coating emits 4.4 tin--s as much, solvent as use of one with

1 lb oer gallon and only 55 oercent as much as one of 4.1 lbs per gallon.

Thus, VOC emission rates could be easily misunderstood by the general public.

1-7
The above disadvantage is eliminated if the solvent content is

expressed in terms of mass of VOC per unit volume of paint solids

(again kg per liter or lb per gallon). Here the relationship is linear

and more readily understood by the public, e.g., a coating containing

2 lbs per gallon of solids releases twice as much VOC as one of 1 lb

per gallon. The disadvantage of this format is that it relies on an

analytical method which has had only limited usage in the industry and

is virtually untried by control agencies. When more experience is

developed with the procedure for measuring the volume of solids in a

coating sample (approved by the American Society for Testing and Materials

it may be reasonable to express limitations in teMns of paint solids.

Until these uncertainties are resolved, it is recommended that limitations

be based on the volume of the coating (minus water). Appendix A presents

1ASTM test methods for determination of the pounds of VOC per gallon

of coating (minus water).

Other options such as lbs or gallons of VOC per lb of coating are

generally less desirable although they may be entirely appropriate for

a given Industry. Basing limitations on the mass of coating or paint

solids is not recommended because the specific gravity of coatings

tends to vary widely with the degree and type of pigmenting employed.

Highly pigmented paints have much greater density than unpigmented clear

coats or varnishes. Furthermore, basing limits on paint mass might

encourage users to employ a greater degree of pigmentation solely to

meet air pollution limits. Mass rather than volume of VOC is

recommended for emission limitations because measurement techniques

are simple and because VOC mass is more closely related to photochemical

oxidant formation.

l-8
For any given industry, it may be desirable to express solvent limits

in terms other than those reconmended in the Preface. In such instances,

it will be necessary to adjust numerical limits such that they provide

the desired degree of control. Appendix D provides equations and charts

through which recommended limits can be translated into other solvent

limitation formats.

The approach outlined above was designed for coating processes where

low-solvent coatings are to be employed. In those few‘industries where

stack gas treatment is a more likely option, it rr?ay be more appropriate

to state emission limits in terms of control efficiency across the incinerator,

adsorber, etci This concept is discussed iti Appendix Ci Uhere limitations

are expressed only in terms of the coating content, it will be necessary

to determine mass emissions from the control system and relate them to

the quantity of coatings applied during the test period. It is often

difficult to determine the consumption of coatings during any given

period and to ascertain the fraction of WC which is directed to the

control device. In most instances, it will be more reasonable to provide

an alternative efficiency requirement for those situations where add-on

control technology is used in lieu of a complying low-solvent coating.

l-9
2.0 CAN COATING

2.1 Summary of Control Technology

Affected Facility *

Two-Piece Can Lines

Control Options

Exterior Coating: Catalytic and noncatalytic incineration

Water-Borne & High-Solids

coatings

Ultraviolet Curing

Interior Spray Coating: Catalytic and noncatalytic incineration

Three-Piece Can Lines

Sheet Coating Lines

Interior Coating:

Exterior Coating:

Water-Borne & High-Solids

coatings

Powder Coating

Carbon Adsorption

Percent Reduction

90

60-90

up to 100

90

60- 90

100

90

Catalytic and non-catalytic

incineration

90

Water-Borne & High-Solids

coatings

60-90

Catalytic and non-catalytic

incineration

90

Water-Borne & High-Solids

coatings

Ultraviolet curing

60-90

up to 100

2-l
Can Fabricating Lines

Side Seam Spray Coating: Water-Borne & High-Solids

coatings

Powder (only for non-cemented

seams)

Interior Spray Coating: Catalytic and non-catalytic

incineration

Water-Borne & High-Solids

coatfngs

Powder (only for non-cemented

seams)

Carbon Adsorption

End Coating Line

Sealing Compound:

Sheet Coating

Water-Borne & High-Solids

coatings

70-95

Carbon Adsorption

Catalytic and non-catalytic

incineration

9 0

9 0

Water-Borne & High-Solids

coatings

60-90

*Any sheet, can or end coating line consists of the coater(s) and I 1ovens(s).

2.2 General Discussion

60-90

100

9 0

60-90

100

9 0

Cans are made in one of two different ways. A "three-piece" can is

made from a rectangular sheet (body blank) and two circular ends. The

metal sheet is rolled into a cylinder and soldered, welded or cemented

at the seam. One end is attached during manufacturing, the other during

packag

from a

can is

fng of the product. The "two-piece" can is drawn and wal

shallow cup and requires only one end which is attached

filled with a product.

l-ironed

after the

2-2
Cans are used as containers for over 2500 different products ranging

from beer and other beverages, meats, fruit, vegetables and other edible

products to tennis balls, motor oil and paints. Cans are fabricated in

over 600 different shapes, styles and sizes. There are, therefore, major

differences in coating practices depending on the can and type of product

packaged in the can.

_ . .._~__ ---- ---

Independent and captive can manufacturers make up the industry. The

independents are a service industry that coat and fabricate cans for a

variety of customer's needs and specifications. A few slants are owned by

independent companies but manufacture cans for a single customer. Captive _2_

can manufacturers coat and fabricate containers only for products of that __/- -- -- -.-_ ~._ __. __-- _- ~. ._ .-.

corporatigL

Can manufacturing plants are typically located either near steel or

aluminum mills or in the vicinity of their customers. In the independent

can industry, the metal sheets for three-piece cans are usually coated near

steel mills, aud the cans are usually fabricated near the customers. The

captive can industry typically coats and fabricates cans in the vicinity

of the plant that uses the cans. About 50 percent of the U.S. can

coating industry is located in California, Illinois, Ohio, Texas, Pennsylvania

and New Jersey. On a regional basis, EPA Region V has about 27 percent

of the U.S. can industry, Region IX about 16 percent and Region III about 12

percent.

Sizes of can manufacturing slants vary. Some plants coat only

the metal sheets, some fabricate only the three-piece cans from the

coated shee&, some fabricate and coat only two-piece cans, and some __-__ ..._._~ -

coat and fabricate only can ends. Othe nlants perform combinations of

these processes.

2-3
2.2.1 Materials Used - The metal sheets tyoically coated in

the three-uiece can manufacturing industry are tinplate, tin-free steel,

black elate and aluminum in gauges ranging from 0.006 to 0.015 inch and

sheet sizes ranging from 30 inches x 32 inches to 37 inches x 42 inches.

Aluminum is widely used in two-piece can manufacturing but some steel is

also used.

The interior base coat is roll coated on the sheets for three-piece

cans to provide a protective lining between the can metal and product.

It is important that the interior base coat does not react with the

product to alter the product's taste, odor, or appearance. All interior

coatinos for cans that will contain edible products must meet Food and

Drug Administration regulations. 12

Some common resins used in the interior base coat are butadienes,

rosin esters, phenolics, epoxies, and vinyls. The coatings in which

these resins are used range from 20 to 60 percent solids by weight,

and organosols that range from 30 to 66 percent solids by weight. 132

The exterior base coat, usually white,is used frequently both on two

and three piece cans to provide exterior protection to the metal and

background for the lithograph or printing operations. Some of the coating

resins used are polyesters, alkyds and acrylics. These coatings are

approximately 55'to 72 percent solids by weight.

Conventional inks used for printing or lithography contain

90 to 99 percent solids by weight.' These inks may be used for

and three-piece cans,with or without exter ior base coat as spec

approximately

both two

ified by

the customer.

2-4
An over-varnish is usually applied directly over the inks to reduce

the coefficient of friction (to allow for proper mobility of the can on

conveyor tracks), to provide gloss, and to prl>tect the finish against

abrasion and corrosion. Some common solvent-thinned coating resins

are acrylics,epoxies, alkyds, and polyesters at solids contents of 30 to 45

percent by weight. '1 ,3

The orimer or size coat is roll coated before the application of the

exterior base coat or ink to provide better adhesion of the coating,

esoecially if a coating has to withstand severe deformation during

stamoing or tooling operations or withstand high temperature processing

operations. The sizing is usually an epoxy, eooxy ester, acrylic, vinyl

or polyester resin.

Over 30 different solvents are used in interior and exterior base

coats, overvarnish and size coat. These include mineral spirits, xylene,

toluene, diacetone alcohol, methyl iso-butyl ketone, methyl ethyl ketone,

isopkorone,Solvesso 100 and 150 (TM), ethylene glycol monoethyl ether

(TM under Cellosolve),ethanol, cyclohexanone, ethylene glycol monobutyl

ether (TM under Duty1 Cellosolve),ethylene glycol monoethyl ether acetate

(TM under Cellosolve acetate), n-butanol, isooropanol, butyl carbinol,

oaraffins, oropylene oxide, mesityl oxide, aliphatic Petroleum hydrocarbons,

di-isobutyl ketone, di-methyl formamide, and nitrooropane.

The coating used for the sideseam on the interior and sometimes on the exterior of three-oiece cans usual1.y contains vinyl and eooxvDhenolic resins at 10 to 4'1 percent solids by weight. Solvents used in

side-seam coatings are xylene, butyl acetate,paraffins, nitropropane,

eel?osolve acetate (TM), methyl iso-bu 11 ketone, mineral spirits, propylenr oxides and toluene. 194

2-5
in

It

The end sealing compound is usually a dispersion of a synthetic rubber

heptane or hexane, and lines the edges of can ends to form a gasket.

contains 30-45 percent solids by weight.'

2.2.2 Processes and Affected Facilities

Two-Piece Cans - The two-piece can manufacturing operation is a continuous,

high speed process and includes both fabricating and coating operations.

These cans are typically used by the beer and other beverage industries.

Figure 2-l shows one method of fabricating and coating two-piece aluminum

cans.

Metal for two-piece cans is received in coil form and is continuously

fed into a press (cupper) that stamps and forms a shallow cup. The cups

go through an extrusion process that draws and wall-irons the cups into cans

in a lubricating solution and trims the uneven edge of the cans. The cans

are then cleansed to remove the lubricating solution, rinsed with hot water,

and dried. Some manufacturers have been required to provide water treatment

facilities to treat the cleansing process water prior to disposal.

The exterior bodies of these cans are sometimes reverse-roller

coated with a white base coat. The base coat is transferred from a feed

tray, through a series of rollers, and onto the can, which rotates on a

mandrel. The coating is cured or baked at 350 to 400°F in single or multipass continuous, high production ovens at a rate of 500 to 2000 cans per

minute.

Several colors of ink are applied to printing blankets on a rotary

printer that transfers the designs and lettering to the can as it rotates

on a mandrel. A protective varnish is sometimes roll coated directly over

the inks. The decorative coating is cured or baked in single or multi-pass,

continuous, high production ovens at 325 to 4OOOF.

After printing, the cans are necked, flanged, and tested. Flanging

facilitates proper md assmbly once the can is filled. Necking allows

3 c
use of a smaller end. Each can is tested for leakage by applying approximately

12 psig of air pressure and monitoring the can for air leakage.

The cans are spray-coated on the interior of the can body and spray

and/or roll coated on the exterior of the bottom end. The viscosity,

spray time, atomization pressure, and temperature during application of

the coating require precise control to provide a continuous protective

film between the product and the can.2

The coating is usually cured or baked in a continuous, single pass

oven at temperatures of 225 to 400°F. Coated cans are stacked on pallets

for shipment to users.

Some two&piece steel cans are sprayed with an additional interior

coating and baked prior to the application of the interior body spray.

Also the cans are necked in and flanged after the final step.

Three-Piece Cans - The three-piece can manufacturing process can be

divided into two operations: sheet coating and can fabricating. The

sheet coating operation may be subdivided further into base coa.'ing of

one or both sides and the printing or lithographing. The base coating

operation consists of applying an interior coating for three-piece

cans and can ends, an exterior background coating, or a size coat if the

customer so chooses.

The sheets are roll coated on one side only by transfer of the

coating from the coating tray, through a series of rollers, and onto

the sheet as shown in Figure -.2. Sheets are then picked up by the preheated

wickets and transported through a continuous, multi-zone, oven. The coating

is cured at temperatures of up to 425°F. Speeds are 70 to 150 sheets

per ninute, depending on the age of equipment and the type of coating.

The sheets are air cooled in the last ZL 1 of the oven. Oven exhaust

rates usually vary between 2,000 and li JO scfm.

2-7
WALL

BASE COAT tRAY

COIL CUPPER IRONER WASHER EXTERlOR BASE COAfER

LPRliiTiR ANil OVER-tii!RIIIti

COATER

c

OVEN INTERIOR. BODY SPRAY

AND EXTERIOR EN0 SPRAY

LEAK

AND/OR ROLL COATER

TESTER

---.~

NECKER AtiD

FLANGER

!-s?VARNISH TRAY

OVEN

Figure 2- 1. Diagram of two-piece aluminum can fabricating and coating operation.
SHEET (PLATE) BASE COATER WICKET OVEN SHEET (PLATE)

FEEDER STACKER

Figure 2-2. Sheet base coating operation.
The sheet printing or lithograph operation (graphic arts) usually

consists of applying one or two colors of ink either on the exterior base

coat, the size coat, or directly on the metal. A varnish is applied directly

over the wet inks. Inks are applied by a series of rollers transferring the

design first to a blanket cylinder, then onto the metal sheet as shown in

Figure 2-3. The transfer of inks is influenced by environmental factors

such as temperature, draft and humidity because the inks can become

emulsified in the presence of water. Varnish is applied to the metal sheets

by a direct roll coater. Inks and overvarnish are cured in a wicket oven

similar to but usually smaller than the base coat oven; exhaust rates are

1,500 to 8,000 scfm.3 If the required design has more than two colors, the

first set of inks is dried in an oven. Another set of inks is then applied

followed by an overvarnish and then baking in an oven.

During the past several years, ultraviolet light curable inks have

been developed which permit the application of up to 4 colors in a single

pass. In addition, some printing inks have been developed that do not

require an overvarnish.

The can fabricating process is the forming of cans from the coated

sheets. Some of these cans have flat surfaces and some are beaded

for extra strength. Figure 2-4 describes a beer and other beverage three-piece

can fabricating line. Sheets are slit into can body size blanks and fed into

a "body maker" in which the body blank is formed into a cylinder. The seam

is welded, cemented, or soldered, and sprayed on the exterior and interior

of the.seam with usually an air-dry lacquer to protect the exposed metal.

On some cans other than beer or other beverage containers, the coating is usually

sprayed only on the interior. The cylinders are flanged to provide proper

can end assembly and may be necked-in depending on the customer's specifications.

2-10
INK

N

I

SHEET (PLATE) LITHOGRAPH OVER-VARNISH WICKET OVEN SHEET (PLATE)

FEEDER COATER COATER STACKER

Figure 2-3. Sheet printing operation.
CAN END, AND THREE-PIECE BEER AND BEVERE 4GE CAN FABRICATING OPERATION

SHEET (PLATE) STACK

SCROLL

STRIP SHEARER

PALLETIZEO LOAD

END FORMER w

dL22 fro)

’ ENDSEAMER ’ OVEN

LEAK TESTER

MER

BODY

SPRAY

NECKEA ANO FL*ANGER

Figure 2-4. Can end, and three-piece beer and beverage can fabricating operation.
The interior of the cylinder is sprayed with a coating to ensure

a protective lining between the beer or other beverage and the can. Cans

used for other products are typically not spray coated.

The spray coating is usually cured or baked in single pass vertical

or horizontal ovens at temperatures of up to 425°F. The oven exhaust

rate is approximately 2,000 scfm.

Open cylinders pass through an "end double seamer" that attaches one

end onto the cylinder. The cans are tested for leakage, then stacked and

palletized for shipment.

Can ends are stamped from coated sheets of metal in a reciprocating

press and the perimeter coated with a synthetic rubber compound that functions

as a gasket when the end is assembled on the can. Solvent-based compounds are

usually air dried and water-based compounds oven dried at approximately 110°F.

The oven exhaust rate is about 300 scfm.

Table 2-l summarizes some typical oven exhaust rates, organ,;c solvent

concentrations, type of fuel used for the curing or baking operations, and

control methods used in the can industry.

Typical organic emission rates for can coating lines are listed in

Table 2-2. For sheet coating lines,88 to 92_percentof-the- solvent-.-isestimated .A-------.-~ ---

-- __-_A-- -._

to be evaporated in the oven-,- --___._ -~. --- -~-

For interior coating, side seam and coating

__ _- ---.-_-

and end sealing sompound line , most of the solvent evaoorates in the

134 -

coating operation.

2.3 Special Considerations

Independent manufacturers have less -ontrol over the coatings used

thar captive manufacturers because the i-?ependents must satisfy a broad

range of customers' product needs and spLlifications. An independent may

ure as many as 300 different coating for? Alations.

2-13
-4

TAME 2-l OFEIIATIoll OF TVPICAC C.&T COATIffi FACItIfIES

PLANT m---m PROCESS

EXHAUST 8AS

SOLVENT

OVEN OVEN EXHAUST COMCENTBATXON

TEMPERATURE ('F) RATE IN SCM x LEL Fun CONTROL NETtaJO(S)

_

Wet Coating Sheet Base Coating 400 8.080-10.000 1 2 Mural Gas Erich oven has a thermal incineratw

(e,'terior L interior)

Sheet Printing 380 4.000-5.000 10-12 Natural 8ar All ovena ducted into one

incinerator.

5ide Seam Air-dried None.

Interior Body Spray 300-350 2,008-3,808 lo-12 Ratura16as Some water-borne.

_ -----

Two-Piece Cans Exterior Base Coat 385 6,800 8-15 Single 20,000 scfm thermal

llrtural incinerator, primry and

Lithograph,and 385 4.006 8-15 6as trcondary heat recovery.

Overvarnish And

Propene

Interior Body and 365 2,000 8-15 Backup

Exterfor End Spray

Sheet Coating Exterior and Interior

Base Coat

Sheet Lfthograph

400 5.000-6.0$ 5-10

380 3,500-4.008 5-10

Ratural

§ns And

Use some uater-borne; plan on

going to water-borne, highsolids and UV coatings. Use

WV for some Inks. _

__---

Sheet Coating, Sheet Exterior and 350-400 4,900

Interior Base Coat

Y

z Three-Piece Cans,

Two-Piece Cans Sheet Printing 315 3.508

Side Seam Air-dried -

Interior Body Spray 300 2,200

Two-Piece: Fxterior 400 2.200

Base Coat

Lithograph 325 2,ooo

Interior Body‘Spray

and End Spray/Rollcoat

225 2,208

Sheet Coating, Sheet Coating 358-425 8,ooo-9.ooo

Three-Piece

Cans and Ends

Side Seam Air-dried

Ends Air-dried

5-15

3-12

lo-15

s-15

5-15

10-15

10-15

Natural

El

Pro ne

Bat up r

Catalyttc incfneration. plan

on goin

s

to water-borne and

hlgh-so ids.

Plan on going to water-borne.

high-solfds, and no-var Inks.

Water-borne on some lines

Plan on going to water-borne

and high-solids.

Plan on going to water-borne

varnish or no-var inks.

Wse water-borne on some lines.

Natural

Gas

ARd

Propane

&ckep

- -

Carbon adsorb@ (bring replaced

by a catalytfc Imlnsrator).

None.

Use some water-borne coatings.

---_ --

fhrce-Piece Can Side Seam

Fabrication (only

Em and beverage 'nterior Body Spray

,..:

Air-dried ,

388-350 7,000

Natural

Gas

_---

None.

~lvn,.
Table 2-2 ORGANIC SOLVENT EMISSIONS FROM CAN COATING PROCESSES

Typical volatile organic Estimated fraction Estimated fraction Typical organic

emissions from coating of emissions from of emissions from emissions,

Process line, lb/hr coater area oven tons/yrb

-. --.

Sheet ' ::d coating line 112 9-12 88-91 160

Sheet lithographic coating line . 65 8-11 89-92 50

Beer and beverage can-side

seam spray coating process

12 100 air-dried 18

Beer and beverage can-interior

body spray coating process

54 75-85 15-25 80

Two-piece can coating line 86 uncertain uncertain 260

End sealing compound line 8 100 air-dried 14

TV

;,

,r,lp*3i . 5oll*ent emissions will vary from line to line as a result of line speed, size of can or sheet being

'+ 'Pe of coating used.

b

Fksed upon normal operating conditions.
Interior coatings must comply with U. S. Food and Drug Administration

(FDA) Regulation No. 121.2514 if the cans are to contain edible products.

The FDA determines compliance with the regulation through a lengthy test

program. First, the coating must be tested to verify that all of the

components in that coating are specified in the FDA list of approved components.

Other tests must be performed to verify that extractables from that coating

are less than 50 ppm. If a coating contains new components not previously

tested by the FDA, an extended period may be required for suitable testi,ng.

Frequently, the customer also performs long-range storage tests (as

long as 18 months) with the interior coating in contact with the product to

determine if there is any change in the product. Interior coatings must prevent

the product from reacting with the can,and the coatings must not react with

the product to alter its taste, odor, or color. Exterior coatings must meet

requirements for flow, gloss, color, hiding, adhesion, fabrication, blocking,

pasteurization, and retorting temperature resistance. Both exterior and interior

coatings are applied in very thin films, usually round O.ODO3 inches. In the

can industry, film thickness is expressed in mg/sq. inch; most range from 1 to

15.

Plants subject to interruptions in natural .gas suooly tynically use

liquefied petroleum gas (LPG) as backup fuel for can ovens. Sulfur dioxide

and other products of combustion of fuel oil may contaminate the coating

and affect product taste. However, if less efficient indirect fired ovens

are employed, fuel oil is acceptable.

Most can (coating ovens are designed to operate at 25 percent of the

lower explosive limit (LEL). Some can manufacturers, especially independents,

operate their ovens at only 5 to 15 percent of the LEL. This is less efficient

from both an energy and air pollution control standpoint because larger

volumes of air must be handled and processed. Some of the reasons cited for

2-16
operating at lower LEL levels are: the variety of temperatures and speeds

required for different coatings, diverse sheet sizes, air volume distribution

requirements, uneven evaporation rates, and the tendency of LEL sensing devices

to foul. Coaters that use uniform coatings and coat uniform sizes of cans or

sheets are more likely to operate their ovens closer to 25 percent of the LEL

than coaters which use a large variety of coatings.

Equipment used for can coating and fabricating varies

of cans coated and manufactured, therefore, the ease of app

with

licat i

control technology will vary. Some existing equipment can apply

age and type

on of pollution

low solvent

coatings without major costs and alterations; other equipment must be replaced

or extensively modified. Also, add-on control equipment is more costly to

retrofit to some lines than others depend ing on the extent of line equ ipment

alterations and structural changes.

The following sections discuss the use of incineration and carbon

adsorption, and conversion to water-borne, high-solids, powder, and ultraviolet

curable coatings to reduce organic emissions.

2.4 Available Control Technology

2.4.1 Option 1 - Incineration

Achievable Reductions - Reductions of organic emissions of 90 to 98 percent

from can coating ovens are achievable using non-catalytic incinerators.

At least 90 percent control is attainable by catalytic incineration systems.

Technical Analysis: Catalyti':- Incineration - Catalytic incineration frequently

can oxidize organic emissions efficiently at catalyst inlet gas stream

temperatures of 500 to 600°F and outlet gas temperatures of 750 to 1,OOO"F.

2-17
Catalysts used in catalytic incineration are usually made of

platinum and therefore,are relatively expensive and may be poisoned.

Its activity or effectiveness is adversely affected by normal aging,

high temperature, and particulate matter, sulfur oxides, and other

contaminants. Natural gas or propane are the preferred fuels for catalytic

incineration because their combustion products will not adversely affect

the catalysts. Normal catalyst life on a can coating line can be 2 to 4

years if the catalyst is not subjected to overheating,due to higher inlet

temperatures and/or higher concentrations,and is not poisoned.

Catalyst efficiency may be monitored by a hydrocarbon analyzer or in

terms of temperature rise and/or pressure drop across the bed. Routine

inspection and periodic cleaning are needed to insure optimum oxidation

of volatile organics.

For details on catalytic incineration, refer to Volume I, Section

3.2.2 of this series.

Table 2-3 presents a comparison of burner fuel requirements for

catalytic incineration with and without heat recovery for two flow rates:

5,000 and 15,000 scfm. As shown in Table 2-3, fuel requirements decrease

with the use of heat recovery. When using both primary and secondary heat

recovery, a net line fuel savings is possible with use of incineration

if all the energy available for recovery can be utilized. As the temperature

of the inlet process gas stream increases and/or the concentration of organics

in the gas stream increases above 15 percent LEL, the potential net fuel

savings using both primary and secondary heat recovery would even be greater.

As the gas stream concentration approaches 25 percent LEL, the fuel value of

the oven exhaust stream increases. If all other factors remain constant,

2-18
TABLE 2-3 BURNER REQUIREMENTS FOR CATALYTIC INCINERATION

WITH VARYING DEGREES OF HEAT RECOVERYay5

Method

Process gas flow rate into

incinerator, scfm

I

5,000 15,000

Catalytic incineration, no heat I

I

recovery

Burner requirements, lo6 Btu/hr

I

1

Net

Gross

i

Catalytic incineration with

primary heat recovery

Primary heat exchanger efficiency,

percent

Burner requirements, lo6 Btu/hr I

Net

Gross I

I

Catalytic incineration with primary

and secondary heat recovery

Secondary air flow, scfm

Secondary heat exchanger efficiency, I

percent

Heat recovered, lo6 Btu/hr

I

Net fuel savings, lo6 Btu/hrb

1.69 5.07

1.80 5.39

36.8 36.8

0.26

0.27

9

0.77

0.82

15,000 45,ono

53.8 53.8

1.33

1.07

3.99

3.22

a 300°F process inlet gas stream, 15 percent LEL concentration.

b

Energy that may be used for energy using facilities other than an

incinerator.

2-19
the temperature of the catalyst bed will increase and its design

temperature may be exceeded. Therefore, the operator may not always

be able to utilize all of the energy potentially recoverable with a

primary system.

Technical Analysis: Non-Catalytic Incineration - Many organic emissions

will oxidize at temperatures of 1,lOO"F to 1,250°F. Cellosolves (TM), toluene,

xylene, and some other organics, however, require 1,400"F to 1,500"F. Effective

bxidation is also dependent on residence time and mixing in the incinerator.

Partially oxldired compounds can be formed ff non-catalytic incinerators are

not maintained at proper oxtdation temperatures and residence times. Noncatelyt1c incineration will also increase NO, levels somewhat over those

experienced with catelytic units.

For details on non-catalytic incinerators, refer to Volume I, Section

3,262.

Table 2-4 presents a comparison of incinerator fuel requirements for

two flow rates t5,000 and 15,000 scfm) and two cases: with and without

heat recovery. Fuel requirements decrease with primary heat recovery,more so

with both primary and secondary heat recovery. A net fuel savihgs may accrue

by using both primary and secondary heat recovery if all of the recovered

energy can be utilized. Moreover, as the temperature or organic concentration

of the inlet process gas stream increases, there will be an even greater net

fuel savings if the available heat can be utilized. However, the can

coaters may often apply a variety of coatings on a line at various organic

solvent contents resulting in varied emission concentrations and variable

fuel requirements.

As shown in Table 2-1, some can coaters are presently using incineration,

typically with 45 percent efficient primary heat recovery, to control emissions

from sheet coating facilities and two-piece can coating facilities. Some

2-20
TABLE 2-4 BURNER REQUIREMENTS FOR NON-CATALYTIC INCINERATORS

WITH VARYING DEGREES OF HEAT RECOVERYa"

Method

Thermal incineration, no heat

recovery

Burner requirements, lo6 Btu/hr

Net

Gross

Thermal incineration with

primary heat recovery

Primary heat exchanger

efficiency, percent

Burner requirements, lo6 Btu/hr

Net

Gross

Thermal incineration with primary

and secondary heat recovery

Secondary air flow, scfm

Secondary heat exchanger

efficiency, percent

Btu recovered, lo6 Btu/hr

Net fuel savings, lo6 BtJ/hrb

Process gas flow rate into

incinerator, scfm

5,000 15,000

4.05

4.30

38.5 38.5

1.56

4.73 .

15,000 45,000

55.2 55.2

1.90

0.34

5.69

0.66

12.16

12.93

1.66

5.03

a 300°F process inlet gas stream; 15 percent LEL concentration.

b

Energy that may be used for eneryy using facilities other than

an incinerator.

2-21
secondary heat recovery is used for preheating the wickets on sheet coating

lines, and for the washers and dryers on two-piece can coating lines.

Costs of Control Option. - The value of recovered energy does not completely

compensate for added operating costs, Table 2-5 provides a comparison of

estimated annual operating costs for various degrees of heat recovery. '

These costs were derived for "ideal" facilities using 5,OQQ and 15,800 scfm

flow rates at 15 percent of the LEL concentration. It was assumed that the

cost of installation is about 40 percent of the equipment costs. However,

the varying degrees of difficulty of retrofitting an incinerator to an existing

facility could increase installat-ion costs by a factor of 2 to 4. The age

and type of can coating equipment, the price of fuel and alactrlcity, labor,

war, enqineering costs and the percent aoerating titne where thy@ is solvent

Input will cause operating costs to vary for each facility.

Catalytic incineration as shown in Table 2-5,is less costly than thermal

incineration in all cases for 5,000 scfm flow rates and for two cases with 15,000

scfm flow rates. However, catalytic incineration is almost equal in cost to

thermal incineration for the 15,000 scfm primary and secondary heat recovery

cases. As more energy is recovered, operating costs of either type incinerator

decrease.

For detailed costs of thermal and catalytic incineration, see Valuma 1,

section 4 of this series.

Effects and Limitations - Adverse environmental effects from incinerators

are mostly dependent on fuels and compounds present in the gas stream, I f

sulfur or nitrogen compounds are present, their oxides can be generated.

If halogens are present, their a-cids will be formed, Sulfur oxides will be

generated by sulfur,in the fuel,oil or in the oven gases. Some nitrcJgen oxides

are always generated by air fixation.

2-22
TABLE 2-5 ESTIMATED ANNUAL OPERATING COSTS FOR

THERMAL AND CATALYTIC INCINhATIONa9b~5

FLOW RATE INTO INCINERATOR:

Type of Incineration

5,000 SCFM 15,000 SCFM

Annual operating Cost per ton of Annual operating Cost per ton of

cost range, organics removed cost range, organics removed

dollars range, dollars dollars range, dollars

Thermal, no heat recovery

~~-_

72,810-91,800 218-918 168,560-225,560 169-752

Thermal, primary heat recovery 52,550-70,550 158-706 99,560-156,560 loo-522

only

Thermal, primary and secondary 39,870-57,850 120-579 52,680-109,680 53-366

heat recovery

Iv

& Catalytic, no heat recovery 55,040 165-550 120,390 121-401

Catalytic, primary heat

recovery only

45,000-49,950

i ,1 b;. . 1 I- ~!vJI*.~ and secondary

heat recovery

37,310-45,310

135-500 85,450-102,450 86-342

112-453 55,060-82,090 55-274

a3000F process inlet gas temperature; 5-15 percent LEC concentration range; $2.00/106 Btu fuel cost; tube and

shell heat exchangers.

b

These calculations are based on continuous 5000 hours per year operating time. However, due to the variety

of coatings applied, and often frequent coating changes in non-captive facilities, the actual operating time

when organic solvents are being emitted may not be 5000 hours per year.
The can industry has generally avoided using fuel-oil-fired ovens

because of potential sulfur contamination that may affect the product

taste. Using fuel oil in the incinerator would necessitate indirect

heat-exchangers to ensure that sulfur compounds do not reach the ovens.

It is important to note that the energy contribution of the oven exhaust

will vary considerably. Solvent will actually enter an incinerator from

many sheet and can coating facilities rarely more than 75 percent of the

operating time of that facility due to coating changes, preparation period,

etc. During this time, the oven and incinerators must be maintained at

operating temperatures, thus using additional fuel. In addition, the

solvent concentration will vary due to coating composition-, film thickness,

line speed, sheet size, etc. To compensate for these variations, it is

common tc install a bypass around the primary heat exchanger. Then during

periods when the exhaust gas contains less organics, the bypass can be

throttled to maximize the inlet temperature to the incinerator.

Incineration is aoplicable for sheet coating_facilim_two-piece can

_ -- _.. -~..~ ~... - _ -.- .____..____ --- _.. -

facilities and three-piece interior body spray coat%ng facilities,because

of their relatively high oven temperature and organic concentration

(around 10 percent of the LEL). Caoturing and incinerating the volatile

organics from side seam spray coaters and end sealing compound anolicators

is more costly and energy intensive because: the exhaust is usually at

ambient temperatures, gas volumes would be large and would contain relatively

low concentrations of organics , and since these coatings are air-dried, there

may be no nearby energy using facilities that can benefit from the

recovered energy.

2-24
2.4.2 Option 2 - Water-Borne/High-Solids/Powder Coatings

Achievable Reduction, - The potential reduction of organic emissions from

converting to water-borne coatings and high-solids coatings is 60 to g0

percent. This depends on the solvent content of the original coating.

The reduction from convers'on to powder coating approaches 100 percent.

- -

Technical Analysis: Water-Borne Coatings - Water-borne coatings contain

a polymer or resin base, water, some organic "cosolvent" and solubilizing

agent. The presence of some organic solvent in water-borne coatings is

necessary to improve stability, flow-out, appearance, as well as to

depress foaming, and control the evaporation rate.6

Problems associated with conversion to water-borne coatings often

vary due to application characteristics and the type of equipment available.

The replacement of certain existing equipment is usually necessary to

protect against corrosion.

Water-borne coatings may be applied by conventional techniques and

other newer methods. One newer-metM~rrent_ly-usec. for--some ti:)n-piece - - ---

beer cans is to apply a wat_er&orne base coat on the entire can. during-the .___------ ---

final-stages of the cleansing section, then bake the coating in an oven.

---.-_. _c

Another method, in the experimental stages, is to coat the interior of

two-piece cans by filling tbem with a water-borne coating, apolyinq

a charge and electrodepositing the coating particles onto the can. This

method of apolication, however, is relatively slow and might require

several such units on each line. This could be a disadvantage to an older

plant which does not have enough room to install these applications.

The temperatures ef the oven zones have to be adjusted to avoid

"bitting" the water-borne coating film. Ithough some water-borne coatings

may rt-uire higher curing temperatures, this increase in energy consumption

2-25
may be balanced by a significant reduction in oven exhaust flow because

Of the reduced input of vOlatile.OrganiCS.

blater-borne coatings are often difficult toclean up after tiv have

dried because they do not remain soluble in their carrier. Also, waterborne coatings should be protected in transport and storage during winter

and summer months. For details on water-borne coatings, see Volume I,

section 3.3.1 of this series.

Technical Analysis: High-Sblids Coatings - "High-solids" coatings have

been defined by various agencies as those with volatile solvent contents of

only 20 or 30 percent by volume. To convert a process to a high-solids

coating may present application difficulties because of the high viscosity

of the material. To lower viscosity, it may be necessary to raise the

application temperature by installing a heating unit as well as changing

the application equipment. For details on high-solids coatings, see

Volume I, Section 3.3.2 of this series.

Technical Analysis: Powder Coatings - Powder coatings approach 100 oercent

solids. Converting to powder coatings necessitates a major change of

application equipment. Powder coating application technology is being pursued

in the can industry for two-piece can interiors, and has been used for the

sjde seam coating of non-cemented three-piece cans. Powder coatings may _/-I_- . . .._

also be applicable as an overvarnish on two-piece cans. However, present

powder coating application technology has not been perfected to produce

the thin continuous film on the can at high speeds, as with solvent or

water-borne. For details on powder coatings, see Section 3.3.3 of Volume

I of this series.

2-26
Cost of Control Options - The cost of converting to water-borne, highsolids, ur powder coatinqs will vary from plant to plant depending on

the type of cans, and the age and design of application equipment.

Some application equipment may require only small adjustments or the

replacement of a spray nozzle; others will require much more extensive

modification.

Water-borne, high-solids and powder coatings are often more expensive

than the pure organic solvent-borne coatings.7 With i'ncreased consumption,

further development and the increasing costs of organic solvents, the overall

cost of low solvent coatings may become less than conventional organic

solvent-borne coatings.

Secondary costs for conversion to low solvent coatings include:

refinements needed to meet customer's specifications and Federal Food

and Drug Administration standards. One independent can company reportedly

has spent more than $4~~000,000 in the last 3 years in the develc,crllent

and testing of water-borne, high-solids, powder and "exempt" solvent

coatings. 4,839

Effects and Limitations - Some water-borne, high-solids and powder coatings

have been developed for the can industry that are comparable in performance

to solvent-borne coatings; they also comply with FDA standards. Since

these coatings are new to thl industry, many customers require extensive

testing because their differer friction characteristics may affect the

mobility of the cans during packaging or they may change the taste of

the oroduct. Many customers conducl inder?qdent tests to determine effects

of a coating on their product.

2-27
The can industry applies very thin films of coating. Many of these

coatings,such as the side seam spray and interior body spray coatings,

are low solids (lo-18 volume percent) coatings at 6.8 to 6.6 pounds of

organic solvent for each gallon of coatfng (minus water). Water-borne

coatings available for some of those applications contain 3.5 to 4.0 pounds

per gallon (minus water). 10,Tl This represents about an 80 percent reduction

in organic emissions over conventional organic coatings. Available waterborne and high-solids sheet and can exterior base coats and overvarnishes

can contain about 2.2 pounds per gallon (minus water). The sheet interior

water-borne or high-solids base coats may contain 2.2 to 2.8 pounds per gallon

(minus water)."

Water-borne,high-solids or pawder castings are not available to

replace all the present organic solvent-borne formulations used in the

can industry. Therefore, this option is not universal. However,

availability of these systems is predicted to increase substantially

over the next several years.

2.4.3 Control Option 3 - Carbon Adsorption

Achievable Reductions - Carbon adsorption units can be used to control

organic emissions with an efficiency of 85 to 90 percent.'

Technical Analysis - A single carbon adsorption unit may be installed on

one can coating facility or on several coating lines together depending

on the location of the coating lines and the type of coating being performed.

Carbon adsorption is most adaptable to"low temperature" processes

using a limited number of solvents such as the can end sealing compound or

the interior body spray coater for beer and beverage cans, because

collecting mixtures of solventfi can be difficult.

2128
Coatings in the can industry may contain as many as ten solvents.

Because of the difficulty in separating-them, the recovered solvent is

probably best used as boiler fuel for generating steam for the regeneration

of the carbon bed. If the solvent is recovered for reuse, additional

distillation would probably be necessary to render it acceptable for reuse

in can coating.

Process gas streams must be cooled below lOOoF for carbon adsorption

to be effective. Also particulate collection may be required since

particulate matter will coat the carbon bed and reduce its adsorption

efficiency. Carbon adsorption systems are not practical if non-filterable

matter is present in the gas stream. For example, silicone coatings

will coat the carbon bed and prevent adsorption. Corrosion of equipment

can occur if the solvents contain acid-forming compounds. If the carbon

adsorption units are located out of doors, improper operation may be

encountered on cold winter days unless care is taken in the design.

An experimental carbon adsorption system that uses the reco:*ard snlvent

as fuel to produce steam for the regeneration of the carbon bed is known to

have been retrofitted to one can coating facility, a sheet coating line.

This unit has not been successful due to plugging of the carbon bed by

condensables and polymerization of some solvents.

Other cited Droblems are: high onerating costs, water-soluble solvents

causing-water pollution, tort ling of the carbon support screen, short useful life

of the carbon, and large fuel and water usage for steam regeneration. This

system is reoortedly being replaced with a catalytic incinerator. Many of

the52 problems causing the carbon adsorber to function improperly were

2-29
related to the relatively higher operating temperatures of the oven

and the mixtures of solvents used. Carbon adsorption is technically

feasible for "lower" temperature operations such as the end sealing

compound, side seam spray or the interior body spray of both two and

three-piece cans. However, capture of the volatile emissions from the

sealing compound and the side seam application areas may be difficult

and costly. This technique, although technically feasible, has not been

commercially demonstrated. For details on carbon adsorption, see Volume

I, Section 3.2.1 of this series.

Cost of Control Option - The costs of carbon adsorption systems to control

organic emissions are sumnarited in Table 2-6. These costs were derived

for an "ideal" facility, where the installation cost is about 40 Dercent

of the cost of equipment. Installation costs will vary depending on

the P1 ant involved and will be higher when retrofitting a carbon adsorber

on an existing facility.

The cost figures are for carbon steel equipment, although some solvents

such as ketones will require more costly alloys to avoid corrosion. costs

will increase also if distillation equipment or filtration of the process

gas stream is necessary. For additional cost data, see Volume I, section

4 of this series.

Z-311
TABLE 2-6. COST OF CARBOil AUS~RPTI&Iid CAN COATING

IllDUSTRY '

Costs

Installed cost, .$

5,:m scfm

15,')0:1 scfm

No credit

for recovered

solvent

162,000

302,000

Recovered Recovered

solvent solvent

credited at at market

fuel value chemical value

162,000 162,000

302,000 302,000

Annual operating

dost, $

5i003 scfm

Y

60,000 42,000 15,000

15,003 SCfl? 142,000 - 90,000 1,000

04

rf\-t of collected

S,ll S,f>I\ t-s , II " ,!I

, II!,) ,.I L.1 !II 25'; 215 100

15,:)OJ SCfFl 145 105 -5c

a3300F inlet process gas teII$JeratUre; 15 percent of LEL concentration.

b

Installation cash assumed to be 40 percent of equipment cost.

'Cost indicates a net qain.
Effects and Limitations - The oven gas stream may contain not only the organic

vanors from the coating but also other products such as from thermal

degradation and volatilization of resin. Some of these may condense to

sticky tar-like particulates. In such a case, the gas stream must be filtered

or scrubbed upstream of the adsorber and the solid waste-must be disposed

in an environmentally acceotable manner. If the filter does not remove

these particulates, the carbon bed will foul. Hhen solvents that are

miscible in water are used, the condensate from the steam used to regenerate

the carbon bed may have to be heated to remove the solvents to avoid a

water pollution problem. Any boiler operating on recovered solvent must be

supplementally fired because of the typically low organic concentrations

of the process gas and the potential water loss of any miscible organics

during steam regeneration of the carbon bed.

2.4.4 Control Ontion 4 - Ultraviolet Curing

Achievable Reductions - The curing chamber is lighted by special lamps

such as mercury vapor lights. Some ultraviolet curing lamps in the can

industry are water cooled and some air cooled. The air cooled systems

exhaust at about 3000 scfm. These ultraviolet curable coatings are specially

formulated to cure in the presence of ultraviolet light. These coatings

although totally organic, may be considered the equivalent of near zero

percent solids since little vaporization takes place during the near

instantaneous curing. Theoretically, UD to 100 oercent reduction of organic

emissions is achievable when using ultraviolet curing technology, however,

2-32
there may be s~~olatilization of low mOlE!CUlar weight COmpOUndS CiLJring

the curing process. The amount emitted will depend on the coating

-.~ ~~.~

formulation; In addition, ozone generated by the lamps, is also emitted.

(The ozone concentration will likely never exceed 1 ppm in the exhaust

air for the ultraviolet systems in the can industry.} 12 Rapid curing,

which.can take place in less than one second, make the process attractive

for high soeed can coating ooerations. 13

Technical Analyses

Ultraviolet curing technology is becoming more attractive to the can

industry partially due to natural gas shortages. Ujtraviolet curing

technology was first applied on sheet coating lines to dry the first two

colors (set) of ink quickly such that another-two colors~of ink could be

-_ ~.~. --

aoplied in the same pass, thereby eliminating the need for oven drying the

first set. Research efforts report some progress in ultraviolet curing of

the exterior base coat, the inks and the overvarnish in a single pass,

followed sometimes by oven baking the coatings to achieve the dtsired

coating film properties. This would not only eliminate individua- oven

baking of the base coat and inks, but would also eliminate almost a'1

organic emissions from the oven since all the coatings would be ul-raviolet sensitive and set before entering the oven. 12,13,14

Ultraviolet light curing technology is also being considered and in

some cases used on a limited basis in other areas of the can industry such

as the curing-of the exterior lf two-piece beer and beverage cans. Progress

in the acceotance of ultraviole coatings for can interiors will likely be

slow because each must await Federal Food ant Drug Administration aooroval

before they can be used.

2-33
For further technical details on ultraviolet curing, see Volume I

section 3.3.8 of this series.

Cost of Control Options - The cost of ultraviolet curable coatings is

about twice as much as conventional coatings because their use is not widespread, and the chemistry of ultraviolet coatings is more complex.

On the other hand, ultraviolet curing reduces energy usage by 60 percent.

The cost of curing equipment for ultraviolet coatings is about one-fifth

that of conventional ovens. The line speed for ultraviolet curing is

comparable to if not greater than that for conventional coating. 1 5

Effects and Limitations - Ultraviolet curing technology is presently

limited to thin semi-transparent coating films although they are being

tested for add+tSonal uses in the can coating industry. There are, however,

coating apnlications (such as some can interiors) that will require a

matter of years before acceptable ultraviolet curable coatings are available.

2.5 Comparison of Control Options and Conclusions

Incineration is a proven retrofit control system that can reduce

organic solvent emissions from can coating facilities. Although incineration can require significant amounts of fuel, installation of primary

and secondary heat recovery systems when feasible, will significantly reduce,

if not eliminate the incremental energy requirements.

Mater-borne, high-solids, powder and ultraviolet curable coatings can

reduce organic solvent emissions to the same degree as incineration and

may use less energy than solvent-borne coatings. Conversion to water-borne,

high-solids, powder and ultraviolet curable coatings has been successful

on some can coating formulations; however, many coatings are still in the

development stages or are undergoing tests for Food and Drug

2-34
Administration and the packaging customer approval. The ability to convert to

water-borne, high-solids, oowder and ultraviolet curable coatings as a

control option will vary from plant to plant depending on the oroduct.

Carbon adsorption can be feasi 61 e for reducing organic emissions on

the interior body and end spray area and oven, the end sealing compound

application area and the side seam spray area. Measures may be needed

in somt cases to clean the process gas stream first. Because different

solvent mixtures are used, the recovered organics may have little market

value. However, the,y can be used as boiler fuel or be incinerated.

Costs of controlling organic emissions from the can coating industry

using low solvent coatings is difficult to determine because of the many

variable factors in the manufacturing process. Incineration is the most

economical retrofit control option when combined with heat recovery.

Control costs for carbon adsorption are greater than incineratio.1 but approach

that of incineration if recovered solvent can be used as fuel.

It may be costly to collect and retrofit add-on control devices to

reduce organic emissions from side seam spray coaters, beer and beverage

can interior spray coaters and ovens, and the can end sealing compound

coaters because 75-100 percent of the organic solvent vapors are now

emitted as fugitive emission: within the plant. Conversion to water-borne,

high-solids or powder coatings is the best control option for those systems.

Moreover, conversion to water-borne, high-solids, powder or ultraviolet

curable coatings for the two-piece can coat nq lines and the sheet coating

lines would be the economical options if _ceptable. Otherwise, incineration

(witk, heat recovery) or carbon adsorotir iwith solvent recovery for fuel)

is rsL;;nmended.

2-35
If incineration or carbon adsorotion is used to reduce emissions,

the coater can either be covered with a hood which is ducted to the oven

exhaust stream or the coater may be enclosed up to the oven entrance so

that the coater emissions are drawn directly into the oven.

The control of orqanic emissions from can coatinq facilities will

most likely require a combination of several control technoloqies because

of the complexity of coatings used and their annlication, and the economic

and energy considerations in any oarticular plant.

2-36
References

1.

2 .

3 .

4 .

5 .

6 .

7 .

a.

9.

1-Q.

11.

12.

13.

14.

15.

Gallagher, V. N., Environmental

Park, N.C. Reoorts of trips to

1975 and 1976.

Protection Agency, Research Triangle

various can coating facilities in

Read, R.T., Recent Developments - -

in Protective Finishes for Metal

Containers, Part I: Internal Organic Coatings. Oil Colour and

Chemists Assoc. -58: 51-56, 1975.

Holt, J.C., Recent Developments in Protective Finishes for Metal

Containers, Part II: External Organic Finishes. Oil Colour and

Chemists Assoc. -58: 57-61, 1975.

Personal communication between Environmental Protection Agency and

a representative of American Can Company, December 1975.

Combustion Engineering Inc., Wellsville, N.Y. Report on Fuel Requirements, Capital Cost and Operating Expense for Catalytic and Thermal

Afterburners, prepared for the U.S. Environmental Protettion Agency

under Contract No. 68-02-1473, (Task No. 13) EPA-450/3-76-031.

Ansfield, J., Powders Competition. Canadian Paint and Finishing.

December 1974.

Henning, C.C., and M.J. Krupp., Compel1 ing Reasons for the Use of

Water Reducible Industrial Coetings. Metal Finishing. October 1974

pp 57-61.

Water-Borne Coatings Developed for Beer, Soft Drink Can Interiors.

Industrial Finishing, December 1974. p 76.

Landauer, L., and C.E. Scruggs, New Can Coatings to Meet Air Quality

Standards - Status Report. American Can Company, Barrington, Illinois

LeBras, L.R., PPG Industries, Pittsburgh, Pa., Letter to Vera Gallagher

in cornnent to draft of this document. Dated August 13, 1976.

Carlson, D.T., Coors Container Corporation, Golden, Colorado. Letter

to Vera Gallagher in comment to draft of this document. Dated

September 13, 1976.

Sallee, Elgin D., Ultraviolet and Other Metal - Decoration Processes,

American Can Company, September 24, 1975.

Shahidi, I.K., J.C. Trebellas, and J.A. Vona. Improving UV Cured Can

Coatings. Celanese Chemical Company; Modern Paint and Coatings; Summit,

New Jersey, July 1375. pp 21-26

Capron, J.W. and R.C. Heininger. Continental Can Corporation, Thor

V Solventless Metal Decorating ;for Three-Piece Cans, Background.

Preoared for the U.S. Environmental Protection Agency, 1976.

Series 600/Z-76-011

Radiation Curing Goes Begging for Coaters. Iron Age. August 18, 1975

Pp 43-52

2-37
3.0 COIL COATING

3.1 Sumnary of Control Technology

Affected

facility

Coil coating line

Control Option

Thermal incineration

Catalytic incineration

Water-borne & highsolids coatings

Percent

Reduction

90-98

9 0

70- 95

Coil coating line consists of the coater(s), the oven(s) and the quench area(s).

3.2 G?neraJ-.Wscussion

Coil coating is the coating of any flat metal sheet or strip that

comes in rolls or coils.' The metal is typically roll coated on one or

both sides on a continuous productton line basis. The metal may also

be printed or embossed. The coated metal is slit and fabricated by

drawing, stamping, roll-forming, or other shaping operations into

finished products to be used for cans, appliances, roof decks, shelvinq,

industrial and residential siding, cameras, culvert stock, cars, gutters,

and many other items'.

"Toll" and "captive" coaters represent the two basic divisions of the

industry. The toll coater is a service coater who accepts orders to

coat metal according to his customers' needs and specifications. The

captive coater both coats the ;etal and fabrisates the product from the

coated metal within the same plant or corporation. Some coil coaters are

both captive and toll coaters.

Coil coating p'lants are tyoically lo lted near industrial areas to

reduce raw material shipping time and cc . About half of the U.S. coil

coati' 4 plants are located in Pennsylvan , Illinois and Ohio. On an EPA

3-1
regional basis, Region V comorises about 46 percent of the coil coaters

and Region III about 28 percent. Plants vary in size based on the

number and the size of the coil coating lines.

Coil coating lines vary in the maximum wi$th of metal they are capable

of coating. The lines can coat metal widths ranging from 0,5G to 72 inches

and thickness ranges of approximately 0,005 to 0.090 fncha$, ci rie speeds

can range IJD to 400 feet per minute with plan3 to go as high as 800 feet

per minute. Some common coil coating line sizes are 18, 26, 48, 54, 60

and 66 inches.

Coil coating 7ine emissions come from the Coating area, the preheat

and baking zones of the oven, and the quench area, These emfssions are

majn'ly volatile organics and other compounds, such as aldehydes, that

result from thermal degradation of volatile organics, Emissions from the

combustion of natural gas, which is typically used to heat the ovens, are

carbon monoxide, unburned fuel, nitrogen oxides, and aldehydes. If fuel

oil is used to heat the ovens, sulfur oxides and greater quantities of

nitrogen oxides,and particulates may also be emitted.2

The major emissions from a typical coil coating operation are

summarized in Table 3-l.

TABLE 3-l EMISSIONS MEASURED F-ROM AN UNCONTROLLED NATURAL GAS FiRED COIL

COATING OPERATION USING SOLVENT-BORNE COATINGS

Pollutant

Hydrocarbons

Carbon monoxide

Nitrogen oxides

(as NJ21

Amount emitted

1.0 lb/lb of coating applied

1 10 . lb/lo3 ft3 gas fired

0.20 lb/lo3 ft3 gas fired

Aldehydes

(as formaldehyde)

0.020 lb/lb coating volatiles

applied when water quench is used

Aldehydes

(as formaldehyde)

0.027 lb/lb coating volatiles

applied when air quench is used

3-2
3.2.1 Materials Used- - The metals coated in the coil coating industry

include various aluminum alloys; steel; plated steel; steel alloys; and

some zinc, brass and copper.

Some plants may use as many as 900 different coatings, each containing

four toten different solvents, and some use as much as 40,000 gallons of

coatings oer month. ApDroximate weight percentages of volatiles in

coatings most often applied in the coil coating industry are shown in

Table 3-2.

TABLE 3-2 COATINGS USED IN COIL CQATING4’5

Volatile

Coatings (weight percent)

Acrylics

Adhesives

Alkyds

Epoxies

Fluorocarbons

Organosols

Phenolics

Plastisols

Polyesters

Silicones

Vinyls

3mm-f (Tp)

Dacromet (TM)

40-45

70-80

50-70

45-70

55-60

10-15

45-50

o-50

45-50

35-50

60-75

The solvents most often used in the coil coating industry include

~ylene~toluene, methyl ethyl ketone, Cellosolve Acetate (TM), butanol,

diacetone alcohol, Cellosolve (TM), Butyl Cellosolve (TM), Solvesso 100

and 150 (TN), isophorone, butyl carbinol mineral spirits, ethanol,

nitroc,opane, tetrahydrofuran, Panasolv 'TM), methyl isobutyl ket-nc,

Hisol TOO (TM), Tenneco T-125 TM), isoplJpanoI abd di isoamyl ke-ne.

3-3
3.2.2 Processes and Affected Facilities - Configurations of coil coating

lines differ from one another. On some lines, the metal is uncoiled at

one end of the line and recoiled at the opposite end. On other lines, called

"wrap around" lines, the metal is uncoiled and recoiled at about the same

point on the line. Some coil coating lines have a single coater and one

curing or baking oven; o thers called "tandem" lines, have several successive

coaters each followed by an oven so that several different coatings may be

applied in a single pass. Figure 3-l is a schematic of a "tandem" coil

coating line.

The metal on the coil coating line is moved through the line by powerdriven rollers. It is uncoiled as the process begins and goes through a

splicer, which joins one coil of metal to the end of another coil for

continuous, nonstop production. The metal is then accumulated so that

during a splicing operation, the accumulator rollers can descend to provide a continuous flow of metal throughout the line. The metal is cleaned

at temperatures of 120°F to 16O"F, brushed, and rinsed to remove dirt,

mill scale, grease, and rust before coating begins, The metal is then

treated for corrosion protection and for proper coating adhesion with

various pretreatments,depending on the type of metal being coated and the

type of coatings applied.

The first or "prime" coat may be applied on one or both sides of the

metal by a set of three or more power-driven rollers. The "pick-up'! roll,

partially immersed in the coating, transfers the coating to the applicator

roll. The metal is coated as it passes between the applicator roll and

the large back-up roll. The metal is typically reverse roll coated.

3-4
ACCUMULATOR ACCUMULATOR

SPI ICER

r-u--c

UNCOILING

METAL

PRIME

_ COATER PRIME PRIME

OVEN QUENCH

METAL CLEANING PRETREATMENT 1 y [--l-,

1

------------. cl

‘ii?q

----__

--a-_

----_

---mer

B

TOPCOAT

COATER

TOPCOAT

OVEN

TOPCOAT

QUENCH

SHEAR

__

“[r, I Ll

RECOILING

METAL

Figure 3-l. Diagram of coil coating line.
Figure 3-2 is a schematic of a t:rpical rollcoater. A third roTl,called

a "doctor" roll,may be used to control film thickness when at:pl:fing a ili?h

viscosit:/ coating,by making contact with the "pick-up" roll.

The applied coating is usually dried or baked in continuous, multizone, high production cateaary, flotation, or double-pass oven. The

temperatures of the preheat, drying or baking zones may range from 100°F to

1000°F depending on the type and film thickness of coating used, and the

type of metal being coated. The flow rates of the ovens' exhaust ma:' vary

from approximately 4000 scfm to 26,000 scfm. Many of these ovens are

designed for operation at 25 percent of the room-temperature lower

explosive level when coating at rated solvent input. AS the metal exits

the oven, it is cooled in a quench chamber by either a spray of water or a

blast of air followed by water cooling.7

A second coat or "topcoat" may be applied and cured in a manner similar

to the prime coat. The topcoat oven, however, is usually longer than the

prime coat oven and contains more zones.

Another method of applying a prime coat on aluminum coils or a single

coat on steel coils is to electrodeposit a water-borne coating to either one

or both sides of the coil. The coil enters a V-shaped electrocoating bath

that contains a roll on the bottom. As the metal goes around the roll,

electrodes on each side can be activated and permit the coagulation of the

paint particles on either one or both surfaces of the coil. The coated coi

is then rinsed and wiped by squeeges to remove the water and excess paint

particles. For steel coils, the electrodeposited coating must be baked in

an oven. For aluminum coils, however, the prime coat is stable enough to

3-6
PICKUP

APPLICATOR ROLL

INTO OVEN

PICKUP ROLL

APPLICATOR ROLL

I -

FLOW OF METAL INTO COATER

Figure 3-2. Typical reverse roll coater.

3-7
immediately go over rolls to the topcoat coater without destroying the

finish, and then be baked as a t\Jo-coat system.6

After cooling, the coated metal passes through another accumu lator, i s

sheared at the spliced section, usually waxed, and finally recoiled. The

accumulator rolls rise during the shearing orocess, collecting the coated

metal to ensure continuous production. Table 3-3 summarizes the ooeration

typical coil coating facilities.

Organic vapors are emitted in three areas of a coil coating line:

the area where the coating is applied, the oven, and the quench area. The

oven emits approximately 90 percent of the organic vapors and a majority

of

of the other pollutants. Of the remaining 10 percent of hydrocarbons emitted,

approximately 8 percent are emitted from the coater area and approximately

two percent are emitted from the quench area. 3s7 Organic vapor emissions

from a tested uncontrolled coil coating facility, reported as methane, are:

coater arek 480 opm; oven, 4950 ppm; and quench area 100 ppm. 117 Considerable

amounts of aldehydes are also emitted from the thermal degradation and

oxidation of volatiles in the ovens. Carbon monoxide emissions mainly result

from improper adjustments of oven burners.3

3.3 Special Considerations - The coil coating industry has exhibited about

15 percent annual growth rate over the past decade compared with the 4 to 5

percent annual growth rate for most other industrial coating industries. 839

The reasons for this rapid growth include the high speed at which the metal ma;

be coated, the low labor costs, the small amount of waste that occurs during

the coating process, the uniformity of film thickness (al though the range of

thickness that can be applied may be limited), the savings on plant space,

the wide variety of coatings and designs available, and the short changeover

times needed when changing coatings.'

3-8
Flow Rate Operating solvent Type of

Line SiTe Ovens scfm TemperatureOF concentration fuel used Control Method

;in width; (in X LEL)

18 inch Prime 4,900

Topcoat 3,400 600

10-20

10-20

Natural

gas

NONE

26 inch Prime 7,400 700 Natural Thermal

Topcoat 12,000 700 25 and less gas incineration

I

31 inch Single 5,000 Zoned at

400-600

Near 25 Natural

gas

Going water-borne

31 inch Single 5,600 Zoned at

300-600

25 and less Electric

I

Plan on going to I

water-borne

w 4E inch Prime 25,900 900-1100 25 and less Natural Catalytic

I '0 Topcoat 11,700 725 gas incinerator

- -~-

54 inch Prime 6,500 Zoned at Flear 25 Electric Plan on going to

Topcoat 12,500 3"@.600 and gas water-borne

54 inch Prime 24;OO0 750 10-15 Natural Thermal

Topcoat 24,000 775 15-25 gas incineration

62 inch Prime 26,000 600 Near 25 Natural Thermal

Topcoat gas incineration

60 inch Prime 35,000 Zoned ai; 25 and less Natural Thermal

Topcoat 300-800 gas jncineration

c-: : t;CT nrime 24 ,GOG Less than 25 Propane Thermal

Topcoat 24,ooc incineration on

each oven
The captive coil coater, because he fabricates his own product, tends

to have more control over the coatings used than the toll coater, b!ho

must meet the needs and specifications of customers. New uses for coil

coated metal are being found continuously as are new coatings. 10

Because of the different post-forming operations that coated coils

must undergo, coatings must survive man)' "acceptance tests", including adhesion,

impact resistance, film thickness, color, sheen, gloss, hardness and resistance

to salt spra;' and abrasion.4 Approximately 65 percent of the coil coated

production is used b,, the building 'ndustr::: therefore, the coatings often

must be resistant to weathering, must provide durable finishes, and must

satisf:* a product ?Jarrantr. 10 Extensive testing (as long as 5 years) may be

required before a coating can be conanercialized6

Natural gas is the ;:rimar:* fuel used in coil coating, and propane is

the primar:! backup fuel during curtailments of natural gas or b:here natural

gas is not available. The coil coating industr.v consumes less than 1 :-ercent

of the U.S. total gas usage. Production has been curtailed in some plants

because of the shortages of natural gas and the lack of availabilit;? of

propane as backup fuel!' In some areas of the country, the gas companies

are not accepting new orders of natural gas. This, counled i.ith increasing

demands for propane are causing some coil coaters to use other forms of fuel

such as oil and electricity to heat the ovens, or oil to fire the incinerators.

Others are lookinq into more efficient methods of baking.

The coil coaters tyzically tr:' to operate the ovens around 25 : ercent

of the lower explosive limit (LEL) as permitted by the insurance companies.

Some are permitted to operate at higher LEL's under special conditions and

3-lfl
reliable LEL monitoring equipment. However, present LEL monitoring

equioment reoortedly requires a high degree of maintenance because

condensate fouls the sensing device. 4

It is not always possible to operate at a high LEL. Coil coaters

are not always able to vary the exhaust flow rates dynamically from each

oven to maintain high LEL's at a given line SDeed when applying a twocoat system.

12

On some coil coating lines, the coater is isolated in a room.

1'

eince the oven is maintained at negative pressure, the organic vapors

from the coater room are Dulled into the oven. Others have hoods over the

coater to exhaust the organic vaoors into the atmosphere. 6-I

Coil coaters are also faced with controlling the water pollution from

their metal cleaning ooerations. Many have been required to install water

treatment systems and have faced the associated sludge disposal oroblems.

Thus, coil coaters are faced with water pollution control and sc?id waste

disoosal costs as well as those of air nollution control.4

3.4 Available Control Technology - The followinq discusses incineration,

water-borne and high-solids coatings, all of which reduce organic vapor

emissions. Other technically feasible control options may be used on coil

coating lines that coat metal for a specific purpose, but they are not

yet aoplicable to the indust-y as a whole.

Electrostatically sprayec pow&r coating is limited because a comolete

selection of acceptable resins is not yet available for use in the coil

industry, and the present aoolication technplogy cannot adequately control

film thickness and edge overlap.

The use of electron beam curinc, is .ited because coating formulations

have r't yet been developed to satisfy t', requirements of the coil coating

industry. The deficiencies may be relet_ to the chemistry nr~s~nt1.y used

3-11
for these coating formulations.12 Ultraviolet curing is limited because it

is presently restricted to thin semi-transparent coatings. Moreover, an

acceptable variety of such coatings has not yet been developed for use by

the coil coating industry.

The use of carbon adsorption is limited because the high oven discharge

temperatures necessitate a large degree of cooling upstream of the adsorber.

Further pretreatment would be required because cracking and nolymerization

of organics form condensable products that can foul or poison the adsorbent.

(Pretreatment by water scrubbing may produce a potential water pollution

problem). Moreover, even after pretreatment by scrubbing or filtering, some

products may still foul the carbon bed, resulting in an inefficient collection

of organic vapors. In addition, there would be little market value for solvents

recovered by this industry because of the mixtures of solvents used and the

expense required to separate them.

Carbon adsorption may be anplicable to certain coil coaters who operate

low temperature ovens and use uniform coating formulations. However, because

the industry is finding new uses for coated coil as well as new coatings that

may poison the carbon, adsorntion is not widely applicable, especially for

independent coil coating operations. If carbon adsorption is considered, it

is advisable to analyze the gaseous and condensable organics in the gas stream

vented from the ovens to assure such control is nractical. For further details

on carbon adsorption, see Volume I, section 3.2.1 of this series.

3.4.1 Option 1 - Incineration - A reduction of over 90 percent in organic

emissions from a coil coating line is achievable using either noncatal:Jtic

or catalytic incineration.

3-12
Technical Analysis - Catalytic incineration oxidizes organic emissions

efficientl:, at catalyst inlet gas stream temJeratures over 500 to 600°F and

catal;st outlet gas stream temperatures of 750 to 1000°F.

The platinum catalysts usually used in catalytic incineration can be

deactivated by: aging or high temperatures, coating with particulate

matter, or poisoning with contaminants. Natural gas or propane is the

preferred,fuel for preheating the gases (if necessary) because of its

cleanliness.

The life of a catalyst on a coi? coating line is about 1 to 2 years,

depending on the inlet gas stream temperature, on the inlet concentration

of organics, and on other pollutants in the gas stream. At higher inlet

temperatures and organic concentrations, the temperature rise from combustion

of the organic vapors increases; thus, the exit temperature in the catalyst

may become too high for normal catalyst life.

The catalyst can be poisoned by certain materials or coated 6s particulate

such as that from siliconized coatings. These will reduce its efficiency if

they are not removed effectively ahead of the catalyst bed.

Catalyst efficienctmay be monitored by a hydrocarbon analyzer or in

terms of temperature rise and pressure drop across the bed. Such routine

inspection and periodic cleaning can insure optimum reduction efficiency of

volatile organics and oossiblv a longer catalyst life.

For further technical details on catalytic incineration, refer to

Volume I, section 3.3.2 of this series.

Table 3-4 presents a comparison of calculated catalytic incinerator burner

requirements for three systems: simple catalytic incineration, catalytic

incineration with "primary" heat recovery, ( -cheat of gases into the

incinerat jr) and catalytic incineration wft' 7rimary and “secondarl*” hoat

3-13
TABLE '3-4 FUEL REQUfRFXWS FOR CATALYTIC ~KMERATORS WTTlf

AND WITHOUT HEAT RECOVERY

% LEL

1 5

2 5

Gas

tumperatureto

cata?yst, OF

Fuel

Reqjrements

10 Btu/hr

Net

Heat exchanger

Gross efficiency, %

600 1.69

500 0

Catalytic

Incineration

no t-teat recovery

Catalytic Incineration ntOh

primary heat recovery

I

Fuel

Requ@ments,

10 &tu/hr

t WQSS

0

0

O

0

aProcess gas flow rate of 15,000 scfm; process gas inlet temperature of 500°F

&Hxtlytic Incineration with pr'imary

and secondary heat recovery

bat exchanger

effkiency, X

5 5

55

5.58 -5.88

6.76 -6.76
recovery (recovery of heat from the incinerator exhaust for procss heat).

As can be seen from Table 3-4, when the concentration of the qas stream

approaches 25 percent of the LEL, and the inlet gas stream temperature

to the combustion chamber is maintained at about 5OO"F, a coil coating

line equipped with a catalytic incinerator may use little, if any,

additional energy for the operation of the burner, even without primary

heat recovery. A primary heat exchanger without a bypass may not save much

energy because the efficiency of the heat exchanger is limited by the upper

temperature limitations of the catalyst. Khen catalytic incineration with

only 55 percent efficient secondary heat recovery is used, there is a net

fuel savings , assuming the recovered heat can be used for process heat.

Coil coating facilities are currently using catalytic incinerators to

reduce organic emissions from their surface coating operations.

Technical Analysis: Noncatalytic (Thermal) Incineration - Noncatalytic

incinerators will oxidize most organics at temperatures of 1100 t; 1250°F.

Some organics, however, such as Cellosolves, (TH), toluene and xylcne

require 1400 to 1500°F incineration temperatures for oxidation. Proper

oxidation is also dependent on residence time (usually 0.4 to 0.6 seconds)

and sufficient mixing. If noncatalytic incindrators are not maintained

at proper oxidation temperatures or residence times, partially oxidized compounds can be formed. Such czmpounds,in some cases, may be harmful.

Noncatalytic incineration may also increase NOx levels from a source. For

further technical details on noncatal.ytic incineration, refer to Volume I,

section 3.2.2 of this series.

iis can be seen from Table 3-5, a significant amount of energy is consumed

c)?n nncatalytic incineration is used tL educe organic emissions. As the

.srganic concentration of the gas stream ib ,reases from 15 percent to 25

Percent of the LEL, the burner requirer?n,s are reduced by almcst

3-15
TABLE 3-5 FUEL REQUIREMENTS FOR NONCATALYTIC INCANFRATQRS WITH

AND WITHOUT HEAT RECOVERY

% LEI

Incinerator

10 heat. recovery

Burner

Requirements,

10 Btu/hr

Noncatalytic Incinerator with

primary heat recovery

Fuel

Requbrements,

Heat exchanger 10 Btu/hr

efficiency, % Net Gross

Noncatalytic Incinerator with primary

and secondary heat recovery

Heat recovered

by secondary Net fuel

Heat exchanger

efficiency, %

hea;oy;a;Fr,

I

gate,

10 Btu/hr

1 5

2 5

9.95 10.58 3 5 3.14 3.36 5 5 6.12 -2.76

5.59 5.95 2 5 1.5 1.65 5 5 6.73 -5.23

I I

aRrocess gas flow rate of 15,000 scfm; process gas inlet temperature of 5OOOF; Incinerator temperature of 1,400OF.

-cioncatwti c
50 percent because of the fuel value of organics. The incinerator would

have to heat only 60 percent as much gas with no change in fuel value.

Primary heat recovery (preheating the incoming gas into the incinerator)

will decrease the burner fuel requirements in the noncatalytic incinerator

as shown in Table 3-5. At a gas stream concentration of 15 percent of

LEL, the energy usage will decrease by about 30 percent with a 35 percent

efficient primary heat exchanger. At 25 percent of LEL concentration,

the energy usage will be the minimum required for noncatalytic incineration

using only a 25 percent efficient heat exchanger. Installation of both

35 percent efficient primary and 55 percent efficient secondary heat

recovery sys&em will result in a net fuel savings if all the recovered heat

is used as process heat. Greater heat exchanger efficiencies will result

in even greater fuel savinqs.

Many coil coating facilities have successfully used either retrofit

or integrated noncatalytic incinerators and both orimary and SE ondary

heat recovery systems.

Cost of Control Option- - Table 3-6 provides a comparison of estimated

annual operating costs and operating costs per ton of emissions removed

by incineration alone and with various degrees of heat recovery, providing

sufficient recovered energy can be used. Operating costs are based on

an assumed inlet process temoerature of 500°F. For further details on

the cost of controlling orgar,+p vapor emissions with noncatalytic and

catalytic incineration, see section 4 of Volume I of this series.

The ooeratinq costs for a coi? coatinq facility using incineration

wil' decrease as the organic concentratior increases, and as more erergy

is r-covered from the incinerators to t !sed for other energy-usinq

MC ses, as can be seen from Table 3-p The difference in o?erl.,' 7

3-17
TABLE 3-6 COMPARISON OF ESTIMATED ANNUAL PERATING COST

FOR COIL COATING INCINERATIO$3 a

Type of Annual Operating Cost

Incineration a;$%&--EL,

Ooerating Cost

per ton of

organics removed

at 15% LEL,

.dollars/ton

Annual opera.ting

cost per year at

25% LEL

dollars

Operating cost

per ton of

organics removec

at 25% LEL,

dollars/ton

Noncatalytiq

no heat recovery

122,580 153 85,540 7 1

Noncatalytic,.

primary heat

recover5 only

74,100 9 3 61,100 5 1

Noncatalytis

primary and

secondary heat

recovery

34,800 4 4 16,910 1 4

Catalytic,

no heat recovery

78,850 9 8 64,450 5 4

Catalytic, primary 75,030 9 4 not applicable not applicable

heat recovery only

Catalytic, orimary and 39,690 II

50 II

secondary heat recovery

Catalytic, secondary

heat recovery only

42,710 5 3 19,670 1 6

iJ recess gas flow rate of 15,000 scfm at 500°F, 4,000 hr/yr operating time, $2.OO/lOo ijTU fuel cost, tube and shell heat

excilangers.
costs for catalytic incinerators with and without primary heat recovery

is minimal orovided that organics constitute at least 15 percent of

the LEL and oven exhaust temperatures are at least 500°F.

For aoncatalytic incineration, the smallest annualized operating

cost is realized when both orimary and secondary heat recovery are used.

Catalytic incineration without heat recovery was found to have lower

annualized operating cost than noncatalytic incineration without heat

recovery.

If the enerqy can be recovered and used, incineration with heat

recovery can reduce net energy consumption compared to a line without

an incinerator. The value of this recovered energy does not, however,

comoletely comoensate for other operating costs, and incineration will

invariably increase overall operating costs. In addition, there is 40

percent more gas to be treated for a given solvent amount, with resultant

increased capital cost, at 15 percent of the LEL than at the same plant

at 25 percent of the LEL.

These costs did not include enclosing the coater area or installing

hoods to duct the coater exhaust into the oven exhaust. Also, these costs

were based on an "ideal" facility where the cost of installation was about

40 percent of the cost of equipment. The degree of difficulty of retrofitting

an incinerator to an existing facility will likely increase the installation

and engineering costs, thereidre, increasing the cost oer ton of organics

removed _.

Effects and Limitations -Adverse environmental effects from incinerators

are mostly dependent. on the comoounds nr _. _:it in the inlet gas stream. I f

suli 'r comoounds are present in the in1 gas stream or in the fuel, their

;>:id; will be generated; ff halogens i;.-= present, their acids may be

fcrmed. Also, nitrogen oxides are gei'? ted from the nitrogen present in

the gas stream.

3-1:
Some of the particulates found in the gas stream, for example, from

siliconized coatings may corrode or foul the heat exchanger tubes. If

the incinerator is not preheated before the operation begins, condensate

and other particulate matter formed in the tubes during shutdown may ignite

and warp the heat exchanger. In addition, catalytic incineration may have

limitations because of catalyst poisoning from some coatings used in

the coil coating industry.

It was assumed in the cost and fuel usage cafcuiatioa that the

exhaust from both the prime and toncoat ovens Is ducted to one incinerator.

Actual solvent input into an incinerator will rarely exceed 85 oercent of

the operating time of a coil coating line due to coating and color changes,

running out a coil of rejected metal, etc. During this time, the ovens

and incinerator must be maintained at ooerating temperatures. ‘* In

addition, it is difficult to maintain an optimum percentage of the LEL

exhaust from each oven. The concentrations can vary wi,th compositions of

- - ----___

the primer and topcoat, film thickness and.line speed. At higher LEL's

- __-_._ -.---- - ~-- -_ .--._~

high heat exchanger efficiencies can cause the incinerator to exceed its

design temperature limits. To minimize fuel usage, the primary heat

exchanger should be designed to handle such varying concentrations, i.e.,

to maximize the heat exchanger efficiency as the solvent input decreases

and lower the efficiency as the solvent input increases. One method of

achieving this is to design a bypass around the beat exchanger. To

ontimize investment and minimize fuel usage and operating costs, each

coil coating ooeration should be studied individually to determine

the most effective heat exchanger eff+ciency. However, the coil

3-21)
mater will still have to base the choice of an incinerator with optimum

heat exchanger efficient:< on the most critical situation.

The use of tube and shell heat exchangers was assumed in the cost

calculations. There are, however, other types of heat exchangers used L?J

the coil coaters. These heat exchangers will var*' in net efficiencies

and in cost; and include the rotating ceramic wheel,packed ceramic beds, air

to liquid heat exchangers and some others. In addition, there are other

methods of operating ovens and incinerators to achieve optimum heat recover-:

and fuel savings such as; inert atmosilhere baking s:/stems !!ith rich fume

incinerators, and the recycling of solvent rich exhaust through zoned incinerators.

3.4.2 Option 2 - Water-Borne and High-Solid Coatings

Achievable Reduction - Water-borne coatings are defined as coatings that

contain a polymer or resin base, water and often some organic solvent or

"cosolvent" that is miscible with water. The presence of a certa'y percentage of organic solvents in water-borne coatings is necessary tc

improve stability, appearance, reduce the "orange-peel" effect, depress

14 foaming and improve edge-pull. Water-borne coatings t:jpicall_v used in

coil coating are water-Isoluble coatings.

High-solids coatings contain a solid composition up to 70

or 80 percent by volume. The remaining portion is organic solvent

necessar,y for proper application and optimum curing characteristics.

Table 3-7 lists the potential percentage reduction, in pounds of

organic solvent per unit volume of coating,which could be realized by

conver-,ina to water-borne and high-solids coatings.

3-21
-_ . ---

TABLE 3-7 POTENTIAL REDUCTIONS FROM USE OF WATER BORNE

AND HIGH SOLIDS COIL COATINGS

Coatinq formulation

(by volume)

Pounds of organic solvent Potential reduction

per gallon of coating by using water-borne

(minus water) coattngs, percent

Water-borne

32% solids

54.4% water

13.6% organic solvents

Or anic solvent-borne

s0% solids

80% solvent

50% solids

50% solvent

70% solids

30% solvent

2.2

5.9

3.7

2.2

--

9 0

5 8

0

3-22
Technical Analysis - Kater-borne and high-solids coatings are easily applicable

with roller coating systems because the; have application characteristics

similar to organic solvent borne coatings. Converting to these coatinas,

however, could present some difficulties.

High-solids coatings are difficult to apply due to high viscosity and may

necessitate heating of the rolls to reduce the viscosity. This may cause a buildup of resin in the rolls unless a three-roll roller coating system is used.

Progress is being made in commercializing medium high to high-solids coatings

for the coil coating industry.

Water-borne coatings have different flow and wetting properties from

solvent-borne coatings. Evaporation of water from an applied coating

cannot be controlled as well as from a solvent mixture. Sometimes coil

coating line speeds must be reduced to avoid popping of the film.

Care must be taken to thoroughly clean the metal prior to coating

because any grease will result in lack of adhesion and edge-covering,

and formation of craters. Also, care must be taken in using certain pretreatments, such as chromic acid, that may cause water-borne coatir,;rs to gel. 14

Tubes, shafts, bearings and other movable parts on a coater must be

replaced or somehow protected from the water-borne coating to avoid corrosion.

In addition, all the pipes and pumps must be replaced with non-corrosive

materials if the coating is pumped from a separate storage or mixing area.

Hokrever, since there exists l-1ttle fire hazard with water-borne coatings,

it is possible to use"tote-bins"inside the plant.

Cleaning dried water-borne coatings is difficult because they do

not remain soluble in their carrier. Water-borne coatings are difficu

dispose of, and are difficult to transnort ard store during the winter

surmer rlonths. 6

It to

and

3-23
Electrodeposited water-borne coatings have been successfully applied

on aluminum and some steel coils. The electrodeposited coated steel is

baked directly after aonlication of the coating. The electrodeposited

coated aluminum can be coated immediateI:, with a topcoat then baked in an

oven. This system not onl:t reduces volatile organic emissions but also

the fuel usage and the costs of a prime coat oven.

For further details on water-borne and high-solids coatings, see

Volume I, section 3.3.1 and 3.3.2 respectivel;r, of this series.

Cost of Control Option - The cost of converting to water-borne or highsolids coatings will vary from plant to plant. Some secondary costs will

result from the necessity to test the coating and its performance on the

line, during forming and during the use of the end-product. It may also be

necessary to alter or adjust the equipment with which the metal is formed

into its final shape.

Some water-borne coatings may require higher curing temperatures than

organic solvent-borne coatings; however, many do not. Increases in

energy maybe counteracted by a reduction in air flow through the oven

necessary in organic solvent systems to maintain the organic vapor concentration below 25 percent of the LEL. It is estimated that in converting to water-borne coatings , a'coil coater may reduce the dilution ai'r

by a factor of four, therefore reducing energ.y consumntion by 50 oercent.

14

Water-borne coatings may be more costly than organic solvent borne

coatings because industrial consumption is not widespread. With increased

consumption, further imnrovements in water-borne coatings and increasing

Cost Of organic solvents, waterqborne coatings may become Tess ?x@ensive than

3-24
organic solvent-borne coatings. 15 High-solid coatings are generally equal

to or more exoensive than equivalent high-solvent coatings.

Effects and Limitations - Water-borne primers, backers,and some low to

medium 910s~ toocoats ,that equal the oerformance of organic solvent borne

coatings have been develooed for aluminum but have not achieved full line

,rspeed in all cases.'

1

For other metals, such as steel, the uses are so

varied that water-borne coatings have not been developed to provide

properties equivalent to all of the present organic solvent-borne coatings

and which can withstand all post-forming operations. Some, however, are

in the early stages of development, but have not reached commercial status. '

Water-borne coatings can contain on the average about 2.2 pounds of

volatile organic per gallon of coating (minus water) as applied. Medium

high solids coatings can contain on the average of 3.1 pounds per gallon

of coating applied (minus water).

3.5 Comparison of Control Options and Conclusions -

Incineration and conversion to water-borne or high-solids coatings

appear to be the most reasonable control options for reducing

organic emissions from coil coating lines because of the typically high

curing temoeratures and the various mixtures of organic solvents found in

the coatings used by this industrv. Incineration, coupled with various

types of heat recovery, has berm successfully anplied to existing coil

coating lines. Similarly, water-borne coatings have been successfully applied,

within limits, to several existing coil coating lines. Over 90 percent

reduction of organic emissions is achievable with incineration and 70-95

oercent reduction is achievable with water-borne coatings, depending on the

orocesses and the solvent level of the 0~ inal solvent-borne coatings

used.

3-25
There are limitations on the options from which to choose. Some

coatings used in the industry can poison incinerator catalysts. There

is a lack of water-borne and high-solids coatings equivalent to organic

solvent-borne coatings for many metal uses, esoecially where resistance

to corrosion or wear is critical, where severe forming operations are performed

or where a high gloss finish is required. Incineration, especially noncatalytic, will increase the use of natural gas or other fuels if no nearby

operations can use the recovered energy.

Ooerating costs of Sncineration for each ton of volatile organic compounds removed are reduced by one half when the concentration of volatiles

is increased from 15 oercent of the LEL to 25 percent of the LEL. Cost

per ton removed for noncatalytic incineration could be reduced further if

concentrations were increased above 25 percent of the LEL. Such high concentrations, however, for catalytic incinerators would exceed their design

temperature limits. If incinerator heat is recovered, costs per ton removed

can be reduced by a factor of 2 to 5 depending on the extent of recovery

and tyne of incineration. The most cost effective systems shown in this

document are noncatalytic incinerators with both Primary and secondary

heat recovery and catalytic incinerators with only secondary heat recovery;

both oxidizing exhausts at 25 percent of the LEL.

If incineration is chosen as a control option, the coater may be

enclose! in a room. Since the ovens are maintained at negative pressure,

the voldtile organics will be pulled into the oven through the oven opening.

A hood may also be installed over the coater area to Lollect tale volatile

organics and exhaust them into the incinerator.

3-26
There does not aooear to be a single best control system for the entire

coil coating industry; therefore, each coil coating facility must be considered separately to determine the most applicable system. 7

3-27
REFERENCES

1 . National Coil Coaters Association; Fact Sheet 1974. National Coil

Coaters Association, Philwlphia, Pa.

2 . A Study of Emissions from the Coil Coating Process, Volume 1. Scott

Research Laboratories, Inc., Plumsteadville, Pa., December 1970,

Prepared for the National Coil Coaters Association.

3. Cosden, W. B., The Ecology of Coil Coating, Metal Finishing, November

1974. op 55-58

4. Gallagher, Vera N., U.S. Environmental Protection Agency, Research

Triangle Park, N.C. Reports bf visits to coil coating facilities.

5. A Study of Gaseous Emissions from the Coil Coating Processes: Volume II

Survey Results, Scott Research Laboratories, Inc., Plumsteadville, Pa.

March 1971, Prepared for the National Coil Coaters Assaciation.

6. LeBras, L. R., PPG Industries, Pittsburgh, Pa,, Letter to Vera N, Gallagher

in comment to draft of this document, letter dated August 13, 1976.

7. A Study of Gaseous Emissions from the Coil Caoting Process and their

Control, Scott Research Laboratories, Plumsteadville, Pa. October 1971,

Prepared for the National Coil Coaters Association .

8 . Hughes, T. W., D. A. Horn, C. W. Sandy, and R. W,

Assessment: Prioritization of Air Pollution from

Operations, Monsanto Research Corporation, Dayton

by U.S. Environmental Protection Agency, Research

under contract No. 68-02-1320 (Task No. 14). Pub

February 1975.

Serth, Source

Industrial Coating

Ohio. Prepared

Triangle Park, N.C.

ication No. 650/Z-75-Olga.

9. Why Coil Coating Growth Continues. Products Finishing, November 1974.

pp 60-61.

10. Moorsman, R., Coil Coating - Past and Present. Products Finishing,

November 1974. pp 163-165

11. Messing, R., Outlook for Natural Gas Suoply. (Presented at National

Coil Coaters Association Convention, Chicago, Illinois - October 3,

1975.)

123. Mil on, C. L., Roner Eastern, Columbia, Md., Letter to Vera Gallaqher

in comment to draft of this document. Letter dated August 10, 1976.

13. Combustion Engineering, Inc., Wellsville, N.Y. Renort of Fuel

Requirements, Caoital Cost and Operatinq Exnense for Catalytic and

Thermal Afterburners. Prepared for the U.S. Environmental Protection

Agency, Research Triangle Park, N.C. under contract no. 68-02-1473

(Task No. 13). Publication No. 450/3-76-031.

14. Anisfield, J., Powders Competition. Canadian Paint and Finishing,

December 1974. pp 41-44

3-28
15. Henning, C. C. and M. J, Krunp, Compelling Reasons for the Use of

Water-Reducible Industrial Coatings. Metal Finishing, October 1874.

DO 57-61

3-29
4.0 FABRIC COATING

4.1 Sumnary of Control Technology

Affected

facility

Coating line

Control system Percentage

or strategy reduction

Incineration 95

Carbon adsorption 90+

Low solvent coatings 80-100

(A coating line consists of the application area and the drying oven.

The application technique may be a roll, knife or rotogravure coater.)

4.2 General Discussion

Fabric coating involves the coating of a textile substrate with a

knife or roller spreader to impart properties that are not initially

present, such as strength, stability, water or acid repellancy or

appearance.'

The fabric coating industry is diverse, concentrated in the

northeastern and southeastern portions of the United States, wiLn a wide

variation in products and plant sizes. The industry consists mainly of -.--~Ismall to moderate size plants each of which specializes in a limited

product line.

Most of the industrial facilities located in the northeast are old;

some are over 40 years of age. (These can be difficult to modify to

achieve an air pollution standard.) Plants in this industry, which is

highly competitive, are usually located near either the textile raw

material producers or industries usinq the coated fabric.

Coating solutions may be either aqueous or organic base. It is the

latter that produces the organic emissions into the atmosphere. It is

estimated that 36 x lo6 kilograms per J. p (80 x lo6 lbs per year) are

emitted in the United States by the vih; coated fabric segment of the

industry. 2

4-l
Rubber, coating of fabrics.is also a larqe scale of solverat emissions,

although nationwide emissions from this source are not currently known.

ADDlicatiOtlS for coated textiles include industrial and electrical

taoes, tire cord, utility meter seals , imitation leathers, tarpaulines,

shoe material, and uDholsterv fabrics.

4.2.1 Materials Used - Substrates (textile materials used to suonort

the coating) can be either natural or man-made. Coating of polyvinyl

chloride (PVC) substrates is covered in this section.

Coatings include latexes, acrylics, polyvinyl chloride, Dolyufethanes,

and natural and synthetic rubbers.

4.2.2 Processes and Affected Facilities - The coating line is the largest

source of solvent emissions in a fabric coating plant, and the most

readily controllable. Some coating plants report that over 70 percent

of solvents used within the plant are emitted from the coating line.

Other plants, especially those involved in vinyl coating, report that only

40 to 60 percent of solvents purchased by the plant are emitted from the

coating line. 3Remaining solvents are lost as fugitive emissions- from

other stages 6f nrocessing and in cleanup. These fugitive losses are

generated by:

1 . Transfer from rail cars or tank trucks to storage tanks,

and subsequent transfer to processing tanks.

2:.Ereathing losses from vents on storage tanks.

3. Agitation of mixing tanks which are vented to the

atmosphere.

4. Solvent evanoration from clean up of the coating applicator

when coating color or tyoe is changed.

4-2
5. Handling, storage and disposal of solvent soaked

cleaning rags.

6. Waste ink disposal. Waste ink is usually distilled

to recover much of solvent. After distillation the sludge,

which still contains some solvent, is usually dumoed in a

landfill.

7. Losses from drums used to store coatings which are being

bumped onto coating applicator. These are usually 55 gallon

drums whichare not hooded and may not even be covered.

8. Cleaning of empty coating drums with solvent.

9. Cleaning coating lines with solvent.

10. Evaporation of solvent from the coated fabric after it leaves

the coating line. From two to three percent of total plant

solvent usage remains in the product. Half of this may

eventually evaporate into the air.

Control techniques for the above types of sources include tightly

fitting covers for ooen tanks, collection hoods for areas where solvent

is used for clean up, and closed containers for solvent wiping cloths.

Figure 4-l shows a general outline of a fabric coating operations.

The following discussions describe these ooerations and control options

for the coating line.

4-3
RUBBER

PIGMENTS C~~RING AGENTB

SOLYLWT

DRYING AND

CURING +

+ COATED PRODUCT

Fig& 4-i. typical fabric coating opemtkm.
COATING

COATED FABRIC TO DRYER

e- SUBSTRATE

HARD RUBBER OR STEEL ROLLER

EXPANDED COATED FABRIC

COATING

SUBSTRATE

Figure 4-2. Knife coating of fabric.1
Milling - Milling is primarily restricted to coatings containing rubber.

Natural and synthetic rubbers are usually milled with pigments, curing

agents, and fillers to produce a homogeneous mass that can be dissolved

in a suitable solvent. Organic solvents are not usually involved in

the milling process; thus, there are seldom any orqanic emissions from this

operation.

Mixing - Mixing is the dissolution of solids from the milling process

in a solvent. The formulation is usually mixed at ambient temperatures.

Sometimes only small fugitive emissions occur. However, some vinyl

coaters estimate that as much as 25 percent of plant solvents are lost

in mixing operations.

Spreading or coating - Fabric is usually coated by either a knife or a

roller coater. Both methods are basically spreading techniques used for

high speed application of coatings to flat surfaces. In some unique

situations, dip coating may be used.

In knife coating, probably the least expensive method, the substrate

is held flat by a roller and drawn beneath a knife that spreads the

viscous coating evenly over the full width of the fabric, Knife coating

may not be appropriate for coating materials such as certain unstable

knitgoods,' or where a high degree of accuracy in the coating thickness

is required. Figure 4-2 illustrates knife coating.

In 'roller coating, the coating material is applied to the moving

fabric, in a direction opposite to the movement of the substrate, by

hard rubber or steel rolls. The depth of the coating is determined by

the gap between rolls (A and B as shown in Figure 4-3). The coating

that is transferred from A to B is then transferred to the substrate

4-6
,

4-7
from roll B. Unlike knife coaters, roller coaters apply a coating

of constant thickness without regard to fabric irregularities.

Rotogravure printing is widely used in vinyl coating of fabrics

and is a large source of solvent emissions. Rotogravure printing uses

a roll coating technique in which the pattern to be printed is etched

as a series of thousands of tiny recessed dots on the coating roll.

Ink from a reservoir is picked up in these recessed dots and is transferred

to the fabric surface. Shadow prints are used to simulate leather grain.

A variety of patterns are printed on such Items as vinyl wall paper.

A transparent protective topcoat over the printed pattern is also applied

with rotogravure techniques.

Solvent emissions from the coating applicator account for 25 to

35 percent of all solvent emitted from a coating line. This solvent

may be collected by totally enclosing the coating applicator in a small

room or booth and sending all booth exhaust to a control device.

However, a total enclosure of the coater may be difficult to retrofit

on many existing lines. Another alternative is to cover the coater

with a hood which can collect most of the solvent emissions.

Drying and Curing - Solvent emissions from the ovens account for 65 to 75

percent of all solvent emitted from a coating line. In most ovens, almost

all solvent emissions are captured and vented with exhaust gases. On

some ctiating lines tne emissions from tne coat-trig anpltcator nood are

ducted to the oven and included with the oven exhaust.

4-8
Estimated and reported solvent concentration levels from drying eperations

range between 5 and 40 percent of the LEL. 4,596 Typically drying ovens

are designed to process fabric on a continuous basis operating with a web

or conveyor feed system. Ovens can be enclosed or semienclosed and,

depending on size, may exhaust from a few thousand to tens of thousands of

cubic feet per minute of air. 7

Obviously, if an add-on control device is

to be installed, it is in the owners best interest to minimize the volume

of air which must be treated.

The oven heat increases the evaporation rate of the solvent and,with

some coatings, will produce chemical changes within the coating solids to

give desired properties to the product. In many cases, evaporation rates are

controlled to give the desired properties to the coated fabric.

High air velocities distribute heat uniformly over the fabric surface,

facilitate heat transfer to the coating and substrate (by minimizing the

laminar zone next to the coated surfaces), and remove the evaporated solvents

from the oven at a rate that will prevent their buildup to explosive levels.

Ovens are heated by natural gas, steam, or electricity. Those heated

by gas may be either direct or indirect-fired. In the direct-fired oven,

the products of combustion are combined with fresh air and circulated over

the material. Indirect-fired, steam heated ovens are the most common

method for heating most existing facilities, although they are less

fuel efficient than direct-firea ovens. They are also limited

in the maximum temperature achievable. One advantage of indirectfired ovens is that the fuel or combustion products cannot

contaminate the product. In electrically htated ovens makeup

air pi,ses over resistance heaters before posure to the fabric.

4-9
Company Product

Alden Rubber

Covaw .

Rubber coated fabric

Tuck Industries

(two p'lants)

Nashua Corporation

(two plants)

~~$$Y~Pn~a~~~er)

Specialty tapes

(fabric atid paper)

Dennison Manufacturing Company Paper

Paper

TABLE 4-1 FABRIC AND PAf%R COATIffi WERAIWJHS

USING CARBOM ADSORPrrON

--l---

Sol vent

Toluene

Toluene

Toluene

Exhaust

Acfm

14,OuO

43,000

20,000

48,wlo 9 6 2 5

Toluene 55,ooo 7 0 1 8

Carbon

&sorption

recovery

percent

8 5

9 5

8 5

Operating

percent

of LEL

5 0

4 5

4 5

(one)
Many drying ovens in older plants are only semienclosed. As a

consequence they draw in excessive dilution air. Solvent concentrations

range between 5 and 12 percent of the LEL according to both calculations

and reports by industyy,. Newer installations are reported to be

operating with exhaust concentrations up to 40 percent of the LEL.4'5

Levels of up to 50 percent of the LEL are possible if proper safety

devices are used according to recent publications. When orwatinq at

at 50 percent of the LEL, the total exhaust rate is only one-fifth (20%) of

that at 10 percent of the LEL. This greatly reduces the cost of a control

system. As shown in Table 4-1, at least three plants in the United States

are operated at 40 to 50 nercent of LEL. 4,5,8,9,1 f-l

4.3 Special Considerations

The fabric coating industry has a number of unique considerations that

affect the technical and economic feasibility of organic emission control.

Although a number of the larger facilities specialize in a specific product,

many plants produce a variety of products or operate on contract to coat

products to a customer's specifications. The latter type, often called

"comnission coaters", must use a variety of coating formulations to comply

with the customer's specifications. The coating may be specified or even

supplied by the customer. The variety of coating specifications causes

variations in emissions which present problems in designing the control

system. Even if the coater knows the solvent compositions, it is necessary

to base exhaust volume and controls upon the most critical or difficult

situation. The number of solvents used al c3 affects the owner's ability

4-11
to recover and reuse the solvent. Thus the coating type is an important

factor in the cost of controlling emissions from a fabric coating plant.

Not only are insurance costs sensitive to the maximum solvent concentration

achieved but also the ayaJlability and cost of fuel also affect the %ign

and cost of control.

These considerations all emphasize that one must define and specify control

technology for many existing plants in the fabric coating industry on a

case-b/-case basis.

4.4 Available Control Technology

Although few companies have elected to use organic emission controls,

there are alternative systems available that are technically feasible.

These are carbon adsorption and incineration. Another approach to reducing

organic emissions is to switch to lower organic solvent coatings such

as aqueous emulsion coatings. These alternatives are discussed in

the following sections.

4.4.1 Option 1 - Incineration - Both catalytic

and thevrnal incinerators (afterburners) can destroy'95 percent

of the organic emissions introduced to them. Since the effectiveness of

the capture and containment system varies from plant to plant, the overall

reduction in coating plant emissions may be less than 90 percent.

Technical Analyses - Incinerators convert organic vapors to carbon dioxide

and water. They have been used by fabric coaters for a number of years to

control v #iatile organics. A detailed description of incineration is given

in Volume I, Section 3.2.2 of this series of reports.

Incinerators can consume large amounts of energy. Fortunately, the

heat they generate frequently can be used within the nlant. A number

'A,*

4-12
of heat recovery schemes are possible including preheating of the

incinerator inlet stream (so called primary heat recovery). Another is

to transfer the heat from the incinerator exhaust gases to supplj/ process

needs (secondary recovery). Primary heat recovery alone can provide

approximately 50 percent of the energy necessary to incinerate gases from

a typical fabric coating system. 11 If the oven exhaust is operated at

greater than 25 percent of the LEL, both primary and secondary heat recovery

can actually decrease overall plant fuel requirements. Fabric coaters usually

can generate all of their steam requirements with secondary heat recovery.

Since the economics of incineration improve with higher solvent concentrations,

the cost of modifying an existing system to maximize the concentration of

solvent in the oven exhaust must be explored when considering retrofitting

a control system. Higher concentrations of solvent also decrease the fuel

requirements for the oven. The prospect of future energy shortages, and ever

increasing fuel costs 'will render such modifications of an oven de;irable

form a cost effectiveness standnoint.

Cost Of Control Options - The cost of installing and operating an incinerator

for an exhaust stream of 15,000 scfm at 25 oercentof the LEL and

300°F is given in Table 4-2. Note that a noncatalytic incinerator (afterburner)

with primary and secondary heat recovery has the lowest annualized operating

cost. If the stream is at a lower inlet temperature, more auxiliary fuel

would be required and operating costs would be higher. Chrpter 4 of Volume

I details the assumptions made in calculating these costs. In assessing

fuel reqtlirements one must consider that coatjlig operations usually operate

ink MtLently and that qreater quantities r fuel are required to

star-r up I incinerator than to operate at - $ady state.

4-13
TABLE 4-2 INCINERATION COSTS FOR A TYPICAL FABRIC

COATING OPERATIONa

Control cost

Installed Annualized $/ton of solvents

oevi ce cost, $ 't;ost, $/yr recovered

Incineration -

No heat recovery

Catalytic 155,000 100,000 5 1

Noncatalytic 125,000 105,000 54

(Afterburner) "-----I------------_____________________------------------------------

Incineration -

Primary heat

recovery

Catalytic 180,000 75,000 3 9

Noncatalytic 150,000 66,000 34

(Afterburner) -----_----------_-----------------------------------------------------

Incineration -

Primary and

secondary heat

recovery

Catalytic

Noncatalytic

(Afterburner)

220,000 54,000b 28b

183,000 26,000b 13b

aProcess rate of 15,000 scfm; temperature of 3OO"F, operation at 25

percent of LEL. See Volume I, Chapter 4 for costs for other

operating paraMzers.

bAssumes heat is recovered and used.

4-14
Effects and Limitations - Energy consumption is a disadvantage of incineration but as discussed both in this Section and in Volume I, recovery

of the heat generated can eliminate or minimize the disadvantage.

Other adverse environmental effects are mostly dependent on the

compounds present in the inlet gas stream. If nitrogen or sulfurcontaining compounds are present in fuel or exhaust gas, their oxides

will be generated. Nitrogen oxides will also be generated from oxidation

of nitrogen present in the combustion air. If halogens are present, acids

will be formed. For a further discussion, see Volume I of this series.

4.4.2 Fption 2 - Carbon Adsorption - A carbon

adsorber can remove over 90 percent of the organic vapors from the gases

that pass through it. Oftencollection efficiency across the carbon bed is

greater than 95 percent. Just as with the incinerator, the inability to

capture 100 percent of the emissions will result in a lower overall plant

reduction. Experience has shown that in plants that use activatec' carbon, the

greatest losses occur in handling of solvent. As care is taken to

minimize handling losses, the overall solvent recovery increases. It ha!: been

reported that 95 percent of the captured solvent vapor can be recovered. 4,lO

Table 4-l identifies some sources that use carbon adsorbers and presents

their effectiveness. These companies all have one factor in common: they

are able to recycle recovered solvent. The importance of this fact can be

seen below under "Cost of Contrc Option."

Technical Analyses - Activated carbon is used not oniy by fabric coaters but by

a number of industries in a variety of coatinn applications. Carbon

adsorbers are particularly attractive for tb,?e sources which use a single

calvenc or which constantly use the same sL dent blend. This permits the

OWTair- ti recycle the solvent without first ,tirifying the recovered msterial.

4-15
For those nlants that must use many solvents or a variety of mixtures,

the recovered material would probably have to be distilled. The

recovered solvent could, of course, always be used as fuel but its fuel

value would always be much lower than its value as a solVent.

Historically, the decision to recover solvent has been based upon

cost effectiveness (return on investment) rather than air oollution

considerations.

Cost of Control Option - Table 4.3 summarizes installation and operating

costs for a 15,000 scfm carbon adsorption unit operating at 170°F and

25 percent of the LEL. Tnree cases are oresented: (1) the solvent has

no value, (2) credit at fuel value and (3) credit at replacmnt value.

Notice that only where the recovered solvent can be recycled does the

i'nvestment oay for itself.

Effects and Limitations - Recovered solvent may be sufficiently watermiscible to Dose a water pollution problem if the condensate from the

steam is not treated before discharge. This is not likely to be a

problem with adsorbers on tke discharge stream from tnost fabric coating

ovens. In cases where this problem exists, it can be solved by treating

the condensate or incinerating the condensate-solvent stream. One

,fabric coating operation that uses a water soluble organic solvent is

,vinyl coating which uses methyl ethyl ketone.

4-16
TABLE 4-3 CARBON ADSORPTION COSTS &OR A TYPICAL FABRIC

COATING OPERATION-'

Case with no credit for

recovered solvent

Case with recovered

solvent credited at

fuel value

Case Gth solvent

credited at market

chemical value

Installed

cost, $

320,000

320,000

320,000

Annualized Control cost

operating $/ton of solvents

cost $/yr recovered

T27,OOO 72

60,000 34

(loo,ooo)c (57Y

aProcess rate of 15,000 scfm, temperature of 17O"F, operation at 25 percent LEL

See Volume I, Chapter 4 for cost for other operating parameters.

bSee Volume I, Chapter 4 for details on cost estimates

'Costs in parenthesis indicate a net gain

4-17
4.4.3 Option 3 - Low Organic Solvent Coatings - Organic emissions can

be reduced 80 to 100 oercent through use of coatings which inherently - -

have low levels of organic solvents. Both high-sol ids and water-borne

coatings are used. The actual reduction achievable depends on the organic

solvent contents of the original coating and the new one.

Teabnical Analyses - Using a coating which has a low organic solvent

content may preclude the need for an emission control device. Often

the coating equipment and procedures need not be changed when a plant

converts to coatings low in organic solvent.

There is only a limited number of cases for which information is

available to compare the resulting coating to its organic solvent

counterpart. Although a number of companies have converted to low

solvent coatings, either in part or in total, ,ne may not Presume them

to be a universal control measure. Each coating line is somewhat unique

and many coated fabricshave different soecifications.

Cost of Control Option - The cost of converting to a low organic solvent

coating and the cost effectiveness of such a strategy is dependent aoon a

number of factors. Research and develooment costs for the coatings may

be high and al though the unit cost will be lowered as use increases, some

users are so specialized that consumption will be small and developmental

costs oer unit volume will remain high.

4.5 Comparison of Control Options and Conclusions

fach control ootion discussed in Section 4.4 is a viable alternative

and probably the best choice for some sources. Ti-z most desirable strategy

for all parties concerned is probably the conversion to low solvent

4-18
coatings. Unfortunately, this option may not be available at present for

all situations.

Carbon adsorotion and incineration are possible for those sources

that cannot use low polluting coatings. Carbon adsorotion is probably the

most economical for sources that use a single solvent or solvent mixture,

but the larqe canital investment required is appreciably greater than for

incineration.

Incineration.; Preferably with primary and secondary heat recovery,

is mos.t annlicable at those sources that use a variety of solvents. Fuel

costs can be reduced by increasinq the organics level in-exhaust gases,

i.e., by reducing dilution air.

4-19
References

1 .

2.

3 .

4 .

5 .

6 .

7 .

8 .

9 .

10.

11.

Smith, J. C., Coating of Textiles. The Shirley Link, The Shirley

Institute, England. pp. 23-27

Telephone communicat4on between W. L. Johnson, U.S. Environmental

Protection Agency and Paul Johnson, Executive Secretary of Chemical

Fabrics and Film Association, August 26, 1976,

letter to James McCarthy, U.S. Environiwntal Pretect~on A ency,

from Vie Sussman, Director-Stationary Source Environmentas Control,

Ford Motor Company, August 6, 1976,

Johnson, W. I.., U,S, Environmental Protection Agency. Trip Report--

Tuck Industries, Beacon, N.Y. Report dated December 2, 1976.

DarvSn, C., U.S. Environmental Protection Agency. Trip Report--

Alden Rubber co., Philadelphia, Pa., Report dated January 26, 1976,

Johnson, W. I., U.S,Environmental Protection Agency. Trip Report--

General Tire and Rubber Co.,

1976.

Toledo, Ohio, Report dated September 15,

Air Pollution Engineering Manual, U.S. Environmental Protection Agency

Research Triangle Park, N.C. Publication No. AP-40. pp 866.

Private communication between C. Darvin, U.S. Envfronmental Protection

Agency and representative of the Nashua Corporation, December 17, 1975.

Johnson, W. L., U.S. Envlronmental Protection Agency, Research Triangle

Park, N.C. Trip Report--Anchor Continental, Inc., Columbia, S.C.

dated November 11, 1975.

Johnson, W. L., U.S.Environmental Protection Agency, Research Triangle

Park, N.C., Trip Report--Dennison Manufacturing Co., Framingham, Mass.,

dated October 14, 1975.

Interim Report by Combustion Engineering Air Preheater, Wellsville, N.Y.

on Catalytic and Noncatalytic Incineration, Environmental Protection

Agency Contract No. 68-02-1413. November 14, 1975.

4-20
5.0 PAPER COATING

5.1 Sunmnary of Control Tecnnology

Affected facility

Coating line

Control technique

Incineration

Carbon adsorption

Percentage

reduction

9 5

90+

Low solvent coatings 80-99

(A coating line consists of the application area and the drying ovens. The

aoplication technique may be a roll, knife or rotoqravure coater.)

5.2 General Discussion

Paoer is coated for a variety of decorative and functional purposes,

using water-borne, organic solvent-borne, or solventless extrusion type

materials. Because the organic solvent-borne coating process is a

source of hydrocarbon emissions, it is an air pollution concern. Among

DrodUCtS that are coated using organic solvents are: adhesive tapes;

adhesivelabels ; decorated, coated, and glazed paper; book covers;

office copier paper (-zinc oxide coated); carbon paper; typewriter ritbons;

and photographic films.

In organic solvent paper coating, resins are dissolved in an organic

solvent or solvent mixture and this solution is applied to a web (continuous roll) of paper. As the coated web is dried, the solvent evaporates

and the coating cures. An organic solvent has several advantages: it will

dissolve organic resins that are not soluble in water, its components can

be changed 3% control drying rate, and organic base coatings show suoerior

water resistance and better mechanical prone ties than some types of waterborne coatings. In addition, a large varie ' of surface textures can

be ohtair X! using solvent coatings.'

5-l
Most organic solvent-borne coating is done by paper converting companies that buy paper from the mills and apply coatings to produce a

final product. The paper mills themselves sometimes applv coatings

but these are usually water-borne coatings consisting of a pigment such

as clay and a binder such as starch or casein.

2

These water-borne

coatings are not normally sources of organic emi5sions.

Mott companies that coat paper using organic solvents are listed

in the U.S. Department of Commerce's Standard Industrial Classification

(SIC) grouping 2641, Paper Coating and Glazing. This group includes

establishments prfmarily engaged in manufacturing of coated, glazed or

varnished papers from purchased paper stock.3 Also included are

establishments primaril:l manufacturing nressure-sensitive tane with backing

of any material other than rubber. Establishments primaril:! engaged in

manufacturing carbon paper are classified in Industry Code 3955 and nhotographic and blue-printed paper in Industry Code 3861, Some type

of paper coating with organic solvents, however, may not fall into an'/

of these groups.

The 1967 Census of Manufacturers4 gives the following information

about companies in SIC 2641:

Total employment in industry: 37,100

Number of oroduction employees 27,000

Total plants by geographic region:

New England

Mid-Atlantic

North Central 117

South 44

We s t 53

Total plants in top ten states for paper coating:

New York

California ::

Massachusetts 40

New Jersey 40

Illinois 34

Ohio 27

5-2
Pennsylvania

Uisconsin

Michigan

Rhode Island

::

16

7

Nationwide emissions of organic solvents from paper coating have been

estimated to be 0.56 million tons/;.ear. 5This estimate includes resin

emissions from solventless pol;!ethJfIene extrusion coatings applied to

milk cartons and resin emissions from water emulsion coatings. Also

included are solvent emissions from rubber adhesives used to glue paper

bags and boxes. A more conservative estimate based on solvent emissions

from the t:!pe of coating operations found in SIC 2641 is 0.35 million tons/yr.

This is slightly less than 2.0 percent of the estimate of 19 million tons/yr

of hydrocarbon emissions from all stationary sources reported in Volume I

nf this series. Manufacturing of pressure sensitive tapes and labels. the

larqest solvent source in SIC 2641, alone accourts for 0.29 million tons/yr.

Solvent emissions from an individual coating facility will var/ with

the size and number of coating lines. A plant ma.' have onl:vf one or as

many as 20 coating lines. Uncontrolled emissions from a single line mav

vary f,rom 50 to 1000 lbs/hr depending on the line size. The amount of

solvent emitted also depends on the number of hours the line operates each

day.

Table 5-l gives tyoical emission data from various naner coating

anolications.

5-3
TABLE 5-l EMISSION DATA FROM TYPICAL PAPER COATING PLANTS

Plant

A

B

c

D

E

F

Solvent

usage,

lb/day

Solvent

emissions

lb/day

10,000

15,000

9,000

1,200

950

Number

of coating

lines

2

5

a

2

10

Control *

efficiency,%

0

Control

device

10,000

15,000

9,000

1,200

24,000

None

0 None

0 None

0 None

9 6 Carbon

adsorptton

9 0 Car&on

adsorption

(not all lines

control led)

2 0 55,000 41,000

1,500 90 Carbon

adsorption

3 5,000

3 21,000 840 9 6 Carbon

adsorption

1 10,500 500 9 6 Afterburner

*Neglecting emissions that are not captured in the hooding system.

5.2.1 Materials Used - The formulations usually used in organic solvent-borne

paper coatings may be divided into the following classes: film-forming

materials, plasticizers, pigments, and solvents. Dozens of organic solvents

are used., The major ones are: Toluene, xylene,methyl ethyl ketone, isonropyl alcohol, methanol, acetone, and ethanol.

Although J single so-lvent is frequently -used, often a solvent mixture

is necessary to obtain the optimum drying rate. Too rapid dt*ying results in

bubbles and an "orgnge peel" effect in the coating; whereas, longer drying

coatings require longer ovens or slower production rates. Variations in the

solvent mixture also affect the solvent qualities of the mix.

5-4
The main classes of film formers used in paoer coating are cellulose

derivatives and vinyl resins. The most commonly used cellulose derivative,

nitrocellulose has been used for paper coating decorative paper, book

covers and similar items since the 1921)'s. It is relatively easy to formulate

and handle, and it dries quickly, allowing lower oven temperatures than

vinyl coatings. The most common vinyl resin is the copolymer of vinyl

chloride and vinyl acetate. These vinyl copolymers are superior to

nitrocellulose in toughness, flexibility and abrasion. resistance. They

also show good resistance to acids, alkyds, alcohols and greases. Vinyl

coatings tend to retain solvent, however, so that comparatively high

temperatures are needed. In general, nitrocellulose is most applicable to

the decorative paner field, whereas vinyl copolymers are used for functional

papers such as some oackaging materials.'

Plasticizers are often added to a coating to improve its flexibility. Three common plasticizers are dioctyl phthalate, tricre:..l

phosphate, and castor oil. Each type of resin has an optimum nlasticizer

concentration. As plasticizer concentration increases, the coating becomes

more flexible until it begins to be too soft and tacky.

In the production of pressure sensitive tapes and labels, adhesives

and silicone release agents are applied using an organic solvent carrier.

The adhesive layer is usually based on one of the following organic

solvent-borne resins: natural tir synthetic rubber, acrylic or silicone.

Because of their low cost, natural and synthetic rubber compounds are the

main ,film formers used for adhesives in pressure sensitive tapes and

label:s, although acrylic and silicone adhesives offer oerformance advantages

for clertain apolications.

5-5
ZONE 1

EXHAUST

HEATED AIR t

FROM BURNER -

7-L

r=l

-II II HOT AIR NOZZLES

I

ZONE 2

EXHAUST

REVERSE ROLL

CDATER I - I CnslUA HULLS

/

OVEW

REWIND

figure 5 7. Typical paper coating he.
WEB

PAPER WEB

L Figure 52. Knife coating of paper.

5-7
The oaoer on which adhesive labels are attached until use are treated

with a release agent so that the adhesive tag may be easily removed.

This is usually a silicone coating that is aoblied with a solvent.

Release agents are also annlied to the backside of pressure sensitive

taoes with organic solvents so that the tapes will unwind easily.

5,2.2 Processes and Affected Facilities 'Figure 5-l shows a typical oaoer

coating line, Components include an unwind roll, a coating applicator

(knife, reverse ro'll, or gravure), an oven, various tension and chill rolls,

and a rewind roll. The unwind, rewind and tension rolls display various

degrees of complexity depending on the design of the line.

The coating applicator and the oven are the main areas of-organic

emission in the paper coating facility.

Coatings may be applied to paper in several ways. The main application

devices are knives, reverse rollers, or rotogravure devices.

A knife coater (Figure 5-2) consists of a blade that scrapes off

excess coating on the paoer. The position of the knjfe (relative to the

paper surface) can be adjusted to control the thickness of the coating.

The knife coater is simply constructed and easy to clean.

The reverse roll coater (Figure 5-3), anplies a constant thickness

of coating to the oaper web, usually by means of three rolls -- each

rotating in the same direction. A transfer roll picks up the coating

solution from a trough and transfers it to a coating roll. (Dometimes

there IS no transfer roll and the coating is pumped directly onto a

coating roll.) A "doctor roll" removes excess material from the coating

roll. The gao between the doctor roll and the coating roll determines

the thickness of the coating. The web is supported by a rubber backing

roll where the coating roll contacts the paper. The coating roll turns

in a direction opposite to that of the paper, hence the name "reverse

5-8
DOCTOR ROLL

METERING GAP

BACKING ROLL

COATING RESERVOIR

/ Figure 53. Four-roll reverse roll coater for paper.

5-9
roll”. This reverse direction of the coating roll reduces striations in

the coating that can form if the coating roll is turned in the same

direction as the paper web.

Knife coaters can apply solutions of much higher viscosfty than roll

coaterr;, thus less solvent is emftted per pound of ,coating applied.

Knife waters handle coatingsmith v(rcositv up t0 10,068 cent4pose(co).

Reverse roll waters operate best in a mu& more dilute range where

visoosity is 300 to 1500 cp. Roll coateti * however, can usual 1y 0oyJerate

at higher speeds, and show less tendency to break the ?aqer- Both kinds

of coaterr apQl;r coamgs of good unminit/.l

Rotogravure, another type of application method used by paper coaters,

is usually considered a printing operation, liith it, the image area on

the coating or rotogravure roll is recessed relative to the nonimage area.

The coating is picked up in the recessed areas of the roll and transferred

directly to the substrate. The gravure printer can print patterns or a

solid sheet of color on a paper web. Rotogravure can also be used to

apply materials such as silicone release coatings for pressure sensitive

tapes and labels. Because of the similarities, this stud;/ is appropriate

for gravure as well as knife and roll coating.

Most solvent emissions from coating paper come from the dryer or oven.

Ovens range from 20 to 200 feet in length and may be divided into two to

five temperature zones. The first zone, where the coated paper enters the

oven, is usuall;! at a low temperature (N 110°F). Solvent emissions are

highest in this zone. Other zones have progressively higher temperatures that

cure the coating after most of the solvent has evaporated. The typical

curing temperature is 25O"F, although in some ovens temperatures of 400°F

are reached. This is generally the maximum because higher temperatures

5-10
can damage tne pa?er. Exhausts streams from oven zones may be discharged

independently to the atmosphere or into a common header, and sent to

some type of air pollution control device. The average exhaust temperature

is about 200°F.

Oven heaters are either direct or indirect fired. lrjith direct-fired

heaters, combustion products contact the coated web inside the oven. The

burners themselves may be inside the oven chamber. More commonl,:, the

burners are mounted external to the oven. In this case, heated air

(along with products of combustion) is blown directly from the burner to

the oven chamber.

Although natural gas is the fuel most often used for direct-fired

ovens, fuel oil is sometimes used. Some of the heavier grades of fuel

oil can create problems because SO2 and particulate may contaminate the

paper coating. Distillate fuel oil usually can be used satisfactorily.

Indirect-fired oven heaters are arranged so that products of combustion do not enter the oven chamber. A heat exchanger of some t.;pe

is used to transfer heat from the burner to the oven ehamber. Because

combustion products do not enter the oven chamber in the indirect-fired

heater, there is no chance for contamination of the naper coating, and

dirtier fuels can be burned. Fuel is not used as efficienctly in the

indirect-fired oven, so more -gel will be required than if direct-firing

is used.

Steam produced in gas or oil-fired boilers is sometimes used to

lIeat oven2 in the paper industry becaur;e .axer coating ovens operate

I" 7airlv low temperatures. (Such boile sould also burn solvent

c jllected b;! a carbon adsorption slistem I Typicall:*, the steam is

,)iped to the oven, and fresh air drawn i CO the oven is heated by

5-11
passing it over the steam coils.

Most paper coaters tr:, to maintain air flow through their ovens so

the solvent concentration will be 25 percent of the LEL, although man:/

ovens are run at much lower solvent concentrations. As the energy shortages intensifies, coaters are making greater efforts to minimize

dilution air and thus raise Sol~~t ctmsentrations.

Although 25 percent of the LEL is often regarded as the maximum

allowable solvent concentration in the oven discharge because of safety

considerations, insurance and safet!l requirements will sometimes permit

even higher solvent concentrations. The Handbook of Industrial Loss

,Prevention notes that flammable vapor concentrations of up to 50 percent

of the LEL may be tolerated if approved continuous vapor concentration

indicator controllers are used. 6

The controller must sound an alarm

when concentrations reach 50 percent, and shut the oven down automaticall:,

when concentrations reach 60 percent of the LEL.

Precise methods are available for calculating the amount of dilution

air needed to maintain the exhaust solvent concentration at a given LEL

level. However, most of the ?aper-converting industry uses the estimation

method of assuming 10,000 ft3 of fresh air, referred to 7O"F, per gallon

of solvent evaporated in the oven.7This method will give a solvent

concentration of ap$roximatel:f 25 percent of LEL for most solvents, but

the r-nge may vary from 10 percent to 32 percent of the LEL for some

solvents.

The exhaust flow rates from paper coating ovens vary from 5OOO to

35,000 scfm depending on size. Average exhaust rates are 10,000 to

20,000 scfm. Paper coating ovens vary in cost depending on web width,

5-12
line speed, and complexity of coating and associated equipment. For

example, some lines have two coating stations SQ that the paper web

may be coated .on both sides. Pa?er coating lines have an installed

cost of $100,000 to $1,000,000. A typical line would cost about $300,000.

In a typical paper coating plant about 70 percent of all solvents

used are emitted from the coating line. The emphasis in this chapter is

on control of the coating line. However, about 30 percent of plant emissions

are from the other sources. These include solvent transfer, storage, and

mixing operations. In order to control solvent emissions from these

areas, provisions must be made to insure that solvent containing vessels

have tight fitting covers and are kept closed. Another often overlooked

source of solvent loss is use of solvents for cleaning various coatings

and sludges from the coating line. This must be done before ever:! color

change. Areas of the coating line that are frequently cleaned with

solvent can be hooded so that solvent fumes arecaotured and sent to

a control device. Dirty cleanup solvent can be collected, distilled and

reused. So.lvent soaked wiping rags should be kept in closed containers.

Almost all emissions of the solvent from the.coating line itself

can be collected and sent to a control device. Many plants report that

96 percent of solvent introduced to the coating line is recovered. Most

of the coating line emissions are from the.oven and the coating application

area. The oven emissions can be exhausted directly to a control device.

Part of the solvent remains with the finished product after it has

cured in the oven. For example, certain t,:$es of jressure-sensitive tapes

have 150 to 2,000 ppm by weight of solvent in the adhesive mass on the

finished tape. Some coaters estimate tl,. t. 2 or 3 percent of solvent

remai: s in the product.

5-13
5.3 Special Considerations

The manufacture of photographic film WtS soecial solvent control

problems. Four or more la:,ers of coatings may be applied to a photographic film, using equipment and coating techniques similar to those

used for other paper coatings. Because the coatings on the photographic

film later undergo chemical reactions, the composition and quality of

the coatings must be tightly controlled. Because of the nature of these

coatings, certain control options ma;' not be practical. For example, it

ma)' be impossible to recover solvents in a carbon adsorption unit and then

reuse these solvents in new photographic coatings since the reclaimed

solvents may contain enough impurities to contaminate the film.

5.4 Available Control Technology

5.4.1 Option 1 - Low Solvent Coatinqs

Achievable Reductions - These are shown in Table 5-2.

TABLE -5-2 ACHIEVABLE SOLVENT REDUCTIONS USING

LOW SOLVENT COATINGS IN PAPER COATING INDUSTRY

Type of low solvent coating Reduction achiewable:%a

Water-borne coatings

Plastisols

Extrusion coatings

80-99

9549

99t

Hot melts 99+

Pressure sensitive adhesives

Hot melt

Water-borne

Prepolymer

Silicone release agents

Water-borne emulsions

100 percent nonvolatile coatings

8O”Z9

99

80-99

99+

aBased on comparison with a conventional coating containing 35 percent

solids by volume and 65 percent organic solvent by volume.

5-14
Technical Analysis - Low Solvent Paper Coatings - A variety of low

solvent coatings have been developed for coating paper. These coatings

form organic resin films that can equal the properties exhibited by

typical solvent-borne coatings for some uses.

Water-borne coatings have long been used in coating paper to

improve printability and gloss. The most widely used types of water-borne

coatings consist of an inorganic pigment and nonvolatile adhesive. Such

older water borne coatings are useful but cannot compete with organic

solvent coatings in properties such as weather , scuff and chemical

resistance. Newer water-borne coatings have been developed in which a

synthetic insoluble polymer is carried in water as a colloidal dispersion

or an emulsion. This a two-phase system in which water is the continuous

phase and the polymer resin is the dispersed phase. L!hen the water is

evaporated and the coating cured, the polymer forms a film that has properties similar to those obtained from organic solvent based coatings.'

Plastisols and organisols are low solvent coatings. Plastiscls are

a colloidal dispersion of a synthetic resin in a plasticizer. !4hen the

plasticizer is heated, the resin particles are solvated by the ,:lasticizer so that they fuse together to form a continuous film. Plast!sols

usuall;/ contain little or no solvent, but sometimes the addition of a

filler or pigment will change the viscosity so that organic solvents

must be added to obtain desiraole flow characteristics. llhen the

volatile content of a plactisol exceeds 5 percent of the total weight, it

is referred to as an organisol.

Plastisol technolog:' began in the i91 's and was first applied to

clot+; vin:fl upholstery in automohi?es i, n example of a plastisol

coatin . . Paper is coated with plastisols to make products such as

5-15
artificial leather goods, book covers, carbon paper and components of

automobile interiors, Plastisals may be applied by a variety of means,

but the most cornnon method is vobably reverse roll coating, Qne

advantage af plastisols 1s that thajl can be applied In layers M? to l/Ef

inch thick, This avoids the neeewlt,.~ turf multiple pagses. through a coating

machine,

condense when emitted from the exhaust stack to form a visible emission.

Companies that MS@ nlaati~ols a4tsn have a small eleet~ostatie precipitator

to remove these droplets Qrom the oven Qxhaust

Hot melt coatings contain no solver% the polymer resins are applied

in a molten state to the pager surfaces. All the materials deposited on

the paper remain as part of the coating, F&cause the hot melt cools to

a 6olid coating soon after it is applied, a drying oven is not needed

to evaporate solvent or to cure the coating, Energy.that would have been

used to heat an oven and to heat makeup air to replace oven exhaust

is therefore saved. Considerable floor space is also saved when an oven

is not used. In addition, the paper line speed can be increased because

the hot melt coating cools faster than a solvent coating can dry.'

One disadvantage with hot melt coatings is that materials that char

or burn when heated cannot be ailplied by hot melt. Other materials will

slowly degrade when the;! are held at the necessary elevated temperatures.

Hot melts may be applied by heated gravure or r-till coaters and are

usually applied at temperatures from 150°F to 450"F.l The lower melting

point materials are generally waxy type materials with resins added to

5-16
increase gloss and hardness. The higher melting point materials form

films that have superior scuff resistance, transparency and gloss.

These coatings form excellent decorative finishes. One Particular

advantage of hot melts is that a smooth finish can be ap:)lied over a

rough textured pa?er. This is possi ble because the hot melt does not

penetrate into the pores of the paper.

A type of hot melt coating, plastic extrusion coating is a solventless system in which a molten thermoplastic sheet is discharged from

a slotted dye onto a substrate of paper, paperboard, or synthetic

material. The moving substrate and molten plastic are combined in a

nip 'between a rubber roll and a chill roll. A screw type extruder

extrudes the coating at a temperature sometimes as high as 600°F. Low

and medium density.polyethylene are used for extrusion coating more than

any other type resins. a

More than 260 extrusion coating lines now produce materials for

Paper, paperboard, and flexible packaging applications.' Hundreds of

products are coated with extrusion coatings. Food packaging mater'als

are often coated by extrusion coatings because a good moisture bah-rier

can be formed. A well known extrusion coated product is the polj!ethylenecoated milk carton, which became popular in the 1960's. Before that

time, milk cartons were coated with wax.

Pressure sensitive adhesives are an area in which lor:: solvent technology is being applied. Because this is a large industry, the potential

for solvent emission reduction is great. In 1974, sales of :!ressuresensitive adhesives in the United States l;:ere over $1 billion, and the

5-17
growth rate about 15 percent per year. Products using pressure sensitive

adhesives include tapes and labels, vinyl wall coverings, and floor

tiles. Nationwide organic solvent emissions from pressure sensitive

tape and label manufacture is -580 mIllion pounds per year.

The three types of low solvent coatings applicable for use as

pres%re sensitive adhesives are: hot melts, water-borne systems, and

prepol ymer sys terns.

Pressure-sensitive hot melts currently being.marketed con&t mostly

of styrene - butadiene rubber block copolymers. Some acrylic resins are

used, but these are more expensive. The capital expense of hot melt

coating equipment is a problem for paper coaters that have already invested

heavily in ca&entional solvent coating equjpment. There are currently

four manufacturers of hot melt coating application equipment for pressure

sensitive adhesives. 9

Water-borne adhesives have the advantage that they can be applied

with conventional coating equipment. Water-borne emulsions, which can

be applied less expensively than can solvent-borne rubber-based adhesives,

arellalready in use for pressure sensitive labeFs, A problem with water

borne adhesives is that they tend to cause the paper substrate to curl

and wrinkle. Some companies have overcome this wrinkle problem, but

many smaller companies have not.

Pre-polymer adhesive coatings are applied as a liquid composed of

monomers containing no solvent. The monomers are polymerized by either

heat orradiation. These pre-polymer systems show promise, but they are

presently only in a developmental stage.

5-18
Silicone release coatings, usually solvent-borne, are sometimes

used for oressure-sensitive, adhesive-coated products. TKO lo~solvent

alternatives are currentlid on the market. The first is a 100 percent

nonvolatile coating which is usually heat-cured, but may be radiation cured.

This is a pre-polymer coating which is applied as liquid monomers that

are cross-linked by the curing process to form a solid fi'lm. The second

system is water emulsion coatings,

Products are being developed that will allow sol.vent recover:/ from

solvent-borne silicone coatings using carbon adsorption. Currently, there

are difficulties with recovering solvent from silicone coatings because

some silicone is carried into the adsorber where it fouls the carbon and

lowers collection efficiency.

TABLE 5-3 CAPITAL COST OF SILICONE CO+&ING SYSTEMS IN

PAPER COATING INDUSTRY

Coatinq systems

, Net sost $/lb of

silicone scyids on paper

Solvent [with sO;l vent recoverv)

Solvent (with solvent incineration)

Solventless (heat cure)

Solvent (with no recoverv) ‘

Water emulsion system

8.20

7.33

7.11

6.69

5.28

The emulsion system is the lowest in cost, but the 100 percent

solventless (pre-pal-ymer) process ma:' prove to be the most practical s;/stem

in the long run. It may be difficult for naper coaters that are familiar

piith organic solvent-borne systems to swi-- h to a water-borne system because

of h) 'nkling of the paper and other app; ation problems.

5-19
Cost of Control Option - Costs will vary for low solvent systems depending

on the type of low solvent coating and the particular end use. The low

solvent coatings will be economical once the technology has been

established, but there can be large costs involved in initially developing

the coatings, purchasing new application equipment and learning to use

the new systems.

Cost comparisons between various low solvent coatings are not as easy

to make as are cost comparisons between various types of add-on control

systems. However, a detailed cost comparison has been made between

1 0

various types of silicone application systems. This comparison is

shown in Table 5-3. The cost of learning to apply water-borne systems

to paper could be very large.

Additional costs will be associated with switching to 100 percent

nonvolatile (pre-polymer) coatings. Most organic solvent-borne silicone

release coatings are currently applied by gravure or reverse roller

None of these are suitable for solventless coatings. Solvent.

less coatings must be applied with 3-roll or 4-roll offset gravure presses.

These cost from $25,000 to $200,000 per coating line. A cost of $100,000

weuld be about average. Because of these costs, availability of capital

can be an impediment to the adoption of solventless silicone coatings.

Effects and Limitations - Most of the low solvent coatings listed here

are currently being used for certain types of products, However, organic

solver,:-borne coatings have been developed over the course of decades,

whereas the low solvent coatings are only now being applied to many

products. Continued research bdill expand the number of applications

for these low solvent coatings; however, at present, low solvent coating

systems are not available for all paper coating applications.

5-20
5.4.2 Option 2--Incineration

Achievable reductions--Thermal (noncatalytic) incinerators may be used to

control organic vapors from paper coating operations. Catalytic incinerators,

widely used for printing operations, have rarely been applied to control

paper coating operations using roll coating or blade coating but certainly

are applicable.

Incinerators, if properly operated, can be over 95 percent efficient

in controlling organic vapors which are directed to the incinerator. The

overall control for the entire plant will be less because of the emissions

which escape captured.

Technical analysis--Incinerators have been retrofitted to a large number

of oven exhausts from paper coating lines to use primary and even secondary

heat recovery. A recent article describes how five paper coating lines

for producing office copier paper were fitted with incinerators, which

were equipped with ceramic wheel heat exchanger. 1' The recovered heat

was used to heat the ovens. Total fuel consumption for the lines actually

decreased after the incinerators were installed. For a discussion OT the

capabilities .and limitations of heat recovery, see Section 3.2.2 of

Volume :I.

cost Of control option--Section 4 of Volume I provides cost data for

incineration at various gas flow rates and temperatures. Exhaust rates from

typical paper coating ovens range from 8,000 to 20,000 scfm at exhaust

temperatures of 175°F to 3OOOF. Costs for catalytic and noncatalytic incinerators onerating on a 15,000 gas stream at 300°F and at 25 percent of the LEL

are given in Table 5-4.

6-21
TABLE 5-4 INCINERATfON COSTS.FOR A TYPICAL PAPER

COATING 'OPERATION"

Device

Xncineration--

No Heat Recovery

catalytic

n ncatalytic

Pafterburner)

Incineration--

Primary Heat Recovery

catalytic

1‘

oncatalytic

afterburner)

Incineration--

Primary and Secondary

Heat Recovery

catalytic

noncatalytic

(afterburner)

Installed

$ cty&

155,000

125,000

180,000

150,OQO

220,000

183,000

100,000

105,000

75,000

66,000

54,000b

26,000b

ccmml

tcost, $/ton

of solvent

fl

51

5 1

3 9

3 4

28b

13b

aProcess rate of 15,000 scfm; temperature of 300°F, operation at 25

percent of LEL.

'Assuning recovered heat can be used.

85-22
Effects and limitations--The major problem associated with the

use of afterburners to control organic vapor emissions from paper coating

lines is the limited availability of natural gas. If heat recovery is

used and the system is operated properly, no additional fuel may be

necessary.

Primary heat recovery refers to using the incinerator exhaust

to preheat oven gases going to the incinerator. Secondary heat recovery

means using heat from the incinerator for plant operations such as heating

the oven or for room heating. Thermal (noncatalytic) incinerators can be

operated at lowest annual expense if both primary and secondary heat

recovery are used. It is possible, however, that the heat recovered from

the secondary heat recovery unit cannot be totally utilized at some Paper

coating plants. Paper coating line ovens operate at relatively low

temperatures, usually around 25OoF and rarely over 400°F so the heat

available to the secondary heat exchanger from the incinerator may be more

than needed by the oven. If some other use for the excess heat cF?not be

found, the full cost savings of secondary heat recovery will not be achieved.

When silicone-release coatings are being applied, silicone compounds

may be emitted. These will foul the heat transfer surface of a shell and

tube heat exchanger and the heat transfer efficiency will decrease,

5.4.3 Option 3 - Carbon Adsorption

Achievable reductions--Carbon adsorption units can be over

90 percent efficient in controlling organic solvent vapors that are drawn

into the carbon bed.

.

5-23
Technical Analysis - Carbon adsorption has been used since the

1930's for collecting solvents emitted from paper coating operations.

Most operational systems on paper coating lines were installed because

they were profitable. Pollution control has usually been a minor concern.

Carbon adsorption systems at existing paper coating plants range in size

from 19,000 to 60,000 scfm. Exhausts from several paper coating lines are often

manifolded together to permit one carbon adsorption unit to serve several

coating lines. Paper products that are now made on carbon-adsorptioncontrolled lines include pressure sensitive tape, office copier paper,

and decorative paper.

Carbon adsorption is,!tnost adaptable to single solvent

processes. Many coaters using carbon adsorption have reformulated

their coatings so that only one solvent is required. Toluene, probably

the most widely used solvent for paper coating, is readily captured in

carbon adsorption systems.

The greatest obstacle to the economical use of carbon adsorption

is that in some cases reusing solvent may be difficult. In many coating

formulations, a mixture of several solvents is needed to attain the desired

solvency and evaporation rates. If this solvent mixture is recovered, it

sometimes cannot be reused in formulating new batches of coatings. Also

if different coating lines within the plant use different solvents and are

all ducted to one carbon adsorption system,then there may be difficulty

reusing the collected solvent mixture. In this case solvents must

be separated by distillation.

5-24
Separation of solvent mixtures by distillation is well established

technology and several plants are already doing this. One paper coating

plant has been using such distillation procedures since 1934. Distillation

equipment can be expensive, however, and it is hard to build flexibility

into a distillation system. Flexibility is needed because many paper

coaters, especially those who do custom work for others, are constantly

changing solvent formulations.

Cost of Control Option - The cost of using carbon adsorption to control

hydrocarbons emissions is outlined generally in Chapter 4, Volume I.

The costs for a plant operating with an exhaust of 15,000 scfm of gas

at '170°F and 25 percent of LEL are given in Table 5-5

TAGLE 5-5 CARBON ADSORFTIOPI' COSTS FOR PAPER COATING IKN!ST!?Y ah

(15,000 scfm, 17O"F, 25% of LEL)

Installed Annualized

cost,$ cost, $/yr

No credit for recovered 320,000 127,000

solvent

Recovered solvent credited

at fuel value

320,000 60,000

Solvent credited at market 320,000

value

(loo,ooo)c

Control

cost, $/ton

of solvent

recovered

125

40

(50)c

aFrocess rate of 15,000 scfm, temperature of 17O"F, ooeration at

25 percent of LEL.

b

See Volume I, Chapter 4 for details on cost estimates.

'Costs in parenthesis indicate a net oain.

5-25
The installed cost qiven above is for a carbon steel adsorber. Certain

solvents such as ketones and ethyl acetate require that the vessel be made

of soecial alloys. These solvents form acids when exposed to steam, and

can corrode carbon steel. Stainless steel alloys are normally used in

these cases, For materials of other than carbon steel, the cost of equipment

increases significantly.

If a distillation unit must be included, the installed cost of the

carbon adsorption system will increase significantly. The installed cost

of the distillation unit will deuend on the number of distillation

columns, the complexity of the separation, and the size of the columns.

These factors will be determined by the quantity, complexity and physical

prooerties of the solvents to be separated.

An example of distillation costs encountered is the separation of a

mixture of 50 percent methyl ethyl ketone (MEK), 25 percent toluene and

25 percent methyl isobutyl ketone (MIBK) into a pure drv MEK stream and

a dry toluene - MIBK mixture. The separation system consists of a

decanter, neutralizing tank and two distillation columns together with

necessary heat exchangers, pumps, structural supports and instrumentation.

The system handles a solvent feed rate of 1.5 gallons per minute which

corresponds to a coating oven exhaust of 15,000 cfm at solvent concentration

of 25 percent of LEL. The cost of this separation system is approximately

$125,000 in carbon steel construction.T2

5-26
Impacts and Limitations - The only adverse environmental effect of carbon

adsorotion is the possibility of small amounts of organic solvent

remaining in the water phase after the carbon bed is steam stripped.

Water pollution has not been reported as a problem by paper coaters

currently using carbon adsorption.

5.5 Comparison of Control 3ptions and Conclusionr

The two proven add-on control devices for controlling organic

solvent emissions from paper coating lines are incinerators and carbon

adsorbers. Both have been retrofitted onto a number of paper coating

lines and are being operated successfully.

The main constraint to the use of incinerators is the possible

shortage of natural gas. However, in many cases the combination of

afterburner and oven will use no more fuel than the oven alone if proper

heat recovery is used. Incinerators can be operated on LPG or distillated

fuel oil if natural gas is not available.

The major drawback to the use of carbon adsorption is that in some

cases solvent mixtures may not be economically recoverable in usable form.

If the recovered solvent has no value, it is more economical to incinerate

and recover heat than install a carbon adsorber. fimever, if the recovered

solvent can be used as fuel, carbon adsorption compares favorably in

operating cost with an incinerator. If the solvent can be recovered as

usable solvent, use of carbon adsorption represents an economic advantage

to the paper coater.

It,is more difficult to estimate costs for low solvent coatings,

because the cost will vary depending on chr type of coating. Low organic

5-27
solvent coatings will usually cost less in dollars per pound of coatings

solids applied than wil? conventional organic solvent coatings with

some type of add-on control device.

5-28
REFERENCES

1.

2.

3 .

4 .

5 .

6 .

7 .

8 .

9 .

10,

11.

12.

Mosher, R. H., and D. Davis. Industrial and Specialty Papers,

Vol. I - Technology. New York, Chemical Publishing Co., 1968.

Cairns, C. W., Evolution of Raw Materials, TAPPI Journal.

Vol. 57, No. 5, page 85, May 1974.

1972 Standard Industrial Classification Manual. U. S. Government

Printing Office. Washington, D.C., p. 1.

1967 Census of Manufacturers, U. S. Department of Commerce,

Washington, D.C

Hughes, T. W., et al, Source Assessment: Prioritization of Air

Pollution from Industrial Surface Coating Operations, Monsanto

Research Corporation, Dayton, Ohio. Prepared for U. S. Environmental Protection Agency, Research Triangle Park, N. C., under

Contract No. 68-02-1320 (Tech. 14) Publication No. 650/2-75-Olga.

February 1975.

Industrial Ovens and Driers, Handbook of Industrial Loss Prevention,

Hightstown, N.J., McGraw-Hill Book Co,, 1967.

Standards for Ovens and Furnaces, Design, Location, and Equipment,

National Fire Protection Association, NFPA No. 86A, Boston, MA, 1973.

Modern Plastics Encyclopedia - 1973-74; Vol. 50, No. lOA, New York,

N.Y., McGraw-Hill, Inc., 1974.

State-of-the-Art in Hot Melt Coating Equipment; Paper, Film and

Foil Converter, September 1975, page 51.

Comparison of Alternatives by Incremental Basis - Cost Per Pound of

Silicone Solids, Dow-Corning, Midland, Mich.

Heat Recovery: Pays for Air Incineration and Process Drying,

Pollution Engineering, Vol. 7, No. 9, pages 60-61, September 1975.

Personal communication between W. L. Johnson, U.S. Environmental

Protection Agency and John W. Drew, Chem-Pro Equipment Corp.,

March 16, 1976.

5-29
6.0 AUTOMOBILE AND LIGHT DUTY TRUCK ASSEMBLY

.-

6.1 Summary of Control Technology

Affected

Facilityg

Prime application,

and flashoff area

Prime cure oven

Topcoat application

and flashoff area*

Topcoat cure oven

(d

b:)

(c)

(4

(4

(f)

(9)

Control Option

Water-borne (electrodeposition)a

>50 volume percent solids primer

Incinerationb

Carbon adsorptionb

Water-borne (electrodeposition)a

>50 volume percent solids primer

Incinerationb

Water-borne topcoata

>50 volume percent solids topcoat

Incineration

Carbon adsorption

Water-borne topcoata

>50 volume percent solids topcoat

Incineration

Percentage

Reduction

85+

80C-93d

OC-65d

go+

4oc ,f- p 3

oc-86 8

go+

85+

4oc,f- 2e,f.

oc-86 %

--_-

90-t

These options reduce emissions from application, flashoff and

cure. The percentage reduction given is the reduction from all

of these sources.

Applicable but not costed in this report since water-borne primer

is likely the preferred method.

Based on an original coating with 50 volume percent solids. (3.7 lbs/gal)

Based on an original coating with 26 volume percent solids.

Surfacer (guidecoat) is included. (5.5 lbs/gal)

Based on an original coating with 12 volume percent solids. (6.5 lbs/gal)

Based on a water-borne topcoat with 2.76 oounds of organic Solvent

Per gallon Of coating minus water (e.g., 25 volune percent solids,

15 volume percent organic solvent and 60 volume percent water).

These control options are applicable to all assembly and subassembly

lines in the plant including those for frames, small parts, wheels,

and main body parts.

*The application area(s) is (are) the ar>a(s) where the coating is

applied by dip or spray. The flashoff lrea is the space between

the annlicatinn area ad the mpn.

.
6.2 General Discussion

For purposes of this study, "automobiles" includes all passenger

cars or passenger car derivatives capable of seating 12 or fewer passengers. "Light duty trucks" includes any motor vehicles rated at 8500

pounds gross vehicle weight or less which are designed primarily for

purposes of transporation of property or are derivatives of such vehicles.

This is intended to include pick-ups, vans and window vans.

The automobile and light duty truck assembly industry receives

parts from a variety of sources and produces finished vehicles ready for

sale to vehicle dealers. Various models may be built on one line, but

they usually are of the same general body style. A plant may have more

than one line. This chapter is intended to apply to assembly plants

only and not to customizers, body shops or other repainters.

Although faster production is possible, automobile and light truck

assembly lines typically produce from 30 to 65 units per hour using two

(or rarely three) worker shifts per day. Plants are usually shut down

on holidays and for several weeks during the model changeover period.

Most plants operate about 4000 hours per year,' depending on demand.

Locations of U.S. automobile and light duty truck assembly plants

include: American Motors--Kenosha, WI, and Toledo, OH; Checker Motors--

Kalamazoo, MI; Chrysler Corporation--Belvidere, IL, Hamtramck, MI,

Detroit, MI (Z), Newark, DE, dnd St. Louis, MO; Ford Motor Company--

Atlanta, GA, Chicago, IL, Dearborn, MI, Kansas City, MO, Lorain, OH, Los

Angeles, CA, Louisville, KY, Mahaw, NJ, Metuchen, NJ, Norfolk, VA, St.

Louis, MO, San Jose, CA, Minneapolis - St. Paul, MN, Wayne, MI, and

Wixom, MI; General Motors--Arlington, TX, Baltimore, MD, Detroit,

6-2
MI, Doraville, GA, Fairfax, KS, Flint, MI, Framingham, MA, Fremont, CA,

.Janesville, WI, Lakewood, GA, Lansing, MI, Leeds, MO, Linden, NJ,

Lordstown, OH, Norwood, OH, Pontiac, MI, St. Louis, MO, South Gate, CA,

Tarrytown, NY, Van Nuys, CA, Willow Run, MI and Wilmington, DE; and

International--Springfield, OH. A plant is under construction by Volkswagen in Pennsylvania. Volvo, who had planned a new Plant in Virginia,

recently announced their plant has been postponed "indefinitely".

Although no "typical" automobile or light truck assembly line

exists, features common to all are shown in Figure 6-l. As the process

begins, an automobile body emerges from the body shop and undergoes

metal treatment (usually a phosphate wash cycle) to improve paint

293 adhesion and corrosion resistance. The first coat, a primer, is

applied by dip and/or spray methods, then the unit is baked. The

topcoat is then applied in one to three steps, usually with a bake step

after each. The painted body then goes to the trim shop where assembly

is completed.

Coatings which are damaged during the trim step are repainted in a

repair spray booth. Because the automobile now contains heat sensitive

materials such as plastics and rubbers, repair is generally limited to

solvent-borne coating, which can be dried in low-temperature ovens.

(Water-borne coatings usually require high curing temperatures.)

Production volume in the repair area is intermittent, making add-on

emission control devices less cost-effective than for the primary

coating area. Emission controls, therefore are generally not practical

for the repair spray booth and its oven. Considerable reductions in

emissions can be accomplished by the use of a higher solids repair coating.

6-3
I

METAL

PRETREATMENT +

DRY-OFF OVEN

FROM BODY SHOP

APPLlCATlDN + PRIMECURE OVEN. _

FIRST TOPCOAT

b APPLICATION AREA

FIRST TOPCOAT

1

’ SECOND TOPCOAT SECOND TOPCOAT

APPLICATION AREA b

CURE OVEN

(IF ANY) (IF ANY)

L

7

COATED PARTS FROM

OTHER LINES

e

3” THIRD TOPCOAT THIRD TOPCOAT TRIM APPLIED

APPLICATION AREA ,. b

CURE OVEN +

b (SEATS, RUGS,

(IF ANY) (IF ANY) DASH, TIRES, ETC.)

c

REPAlP TOPCOAT

APPLICATIO AREA

REPAIR TOPCOAT

OVEN

’ (LOW TEMPERATURE)

b

FINISHED

PRODUCTS

Figure6-1. -General flow diagram for automotive and light truck assembly plants. Main bodies

may be on separate lines from hoods and fenders.

6-4
Cost estimates and pollutant emissions presented in this chapter

are based on coating main body parts including hoods and fenders. In

some plants (particularly those building larger vehicles), hoods and

fenders are coated separately and joined to the body after coating. The

total cost of controlling emissions may be more if the coating is done

on several lines instead of one line.'

Some automobiles and most trucks have a separate frame that is

joined to the body after coating. Frames and small parts such as wheel

rims may arrive at the assembly plant already coated or may be coated at

the assembly plant. These sources of emissions are liable to the same

control measures as those for the main body and this report applies.

Parts that are not visible from the exterior of the vehicle may be

dipped in a viscous coating that can be either water-borne or solventborne. ,yeaAl 4 nh+ ny,tr. frames and other visible sma!! parts may arrive at the

assembly plant already coated, be coated after assembly to main body

parts, or be coated on a separate line. As with the other vehicle

components, the coating process for these parts is liable to the same

control measures used for the main body.

Uncontrolled organic emissions from coating vehicles with organic

solvent-borne surface coatings can range from less than 600 pounds per

hour (lb/hr) to more than 4000 lb/hr for an assembly line. This wide

range is caused by variations in the surface area coated for different

vehicles, the number of vehicles coated per hour, and, most importantly,

the solvent content of the coatings. There may be more than one assembly

line at a plant.

6-5
Other sources of organic emissions from a vehicle assembly plant

that are not included in this study include the application of adhesives

and sound-proofing materials. These account for about 10 to 30 percent

of total organic emissions from the plant.

6.2.1 Materials Used - Two types of coatings are used in this

industry: lacquers and enamels. Lacquers are resin-pigment combinations

dissolved in a high solvent-power solvent. Drying occurs by evaporation

of the solvent and deposition of the resin and pigment, rather than by ,

cross-linking. 4 Enamels are highly pigmented drying oils thinned with a

low-solvent-power solvent. The coating is formed by polymerization.

The uses of coatings can be divided into primers and topcoats.

Acrylic coatings may be either lacquers or enamels and are widely used

for topcoats. Topcoats currently used contain from about 14 to 35

percent solids by volume. Primers are usually enamels and are complex

polymers prepared from epoxy and drying oil acids. Primers are usually

either solution epoxies (cross-linked with a urea or melamine) or

electrodeposition primer resins. 2

A typical solids content of a solventborne primer enamel would be 26 volume percent for General Motors4

and

30-35 volume percent for Ford."

Since most manufacturers apply about a 3.0 to 3.5 mils thick

coating, the mass of solvent emitted per unit surface area Is proportional to the ratio of solvent to solid material in the coating. The

relatiunship between pounds of solvent (assuming a solvent density of

6.6 lbs/gai) emitted per gallon of solids applied and the percentage

6-6
of organic solvent present is shown in Figure 6-2. The relative

positions of the various types of coatings emphasize the great differences in emissions between coatings of different solids content,

e.g., between lacquers and enamels. Even though the positions Of

lacquers and enamels on this figure do not represent absolute numbers

(since exact percent solids and solvent density can vary), the difference is striking. The amount of organic solvent contained per unit

of solids (as used) factor is a convenient comparative tool because it

is independent of vehicle size, line speed, and coating thickness.

6.2.2 Processes and Affected Facilities - Four types of facilities are

affected: (1) prime application area(s), including flashoff area

(evaporation area prior to the oven); (2) prime cure; (3) topcoat

application area(s), including flashoff area but excluding repair

application area; and (4) topcoat cure, excluding repair oven.

The prime coat serves the dual function of protecting the surface

from corrosion and providing for good adhesion of the topcoat. A

combination of manual and automatic spray methods, with or without the

use of electrostatic techniques, is usually used to apply organic

solvent-borne primer. Because workers are in the spray area; health

regulations require solvent concentrations be kept low. At some plants,

vehicle hoods and fenders may have their own prime spray booth and oven.

In 'rare cases, primers may be applied in more than one step with each

followed by curing.

Primers may also be applied by dipping techniques. The Chrysler

Corporation, for example, uses water-borne dip primers for underbodies

\

1..

6-7
POUNDS OF ORGANIC SOLVENT EMITTED PER GALLON OF SOLIDS APPLIED

I T

t

T

NONAQUEOUS 1

DISPERSION ENAMEL (40% SOLIDS)

I

GGGi

- LACGUER

URETHANE (60 PERCENT SOLIDS)

I

NONAQUEOUS

iPERSlON ENAMEL (56% SOLIDS)

I 1

32 PERCENT SOLIDS, WATER-BORNE SPRAY (60/20)

I i I

40 PERCENT SOLIDS, WATER-BORNE SPRAY (60/20)

I I

HIGH SOLIOS (60 PERCENT SOLIDS)

I

50 PERCENT SOLIDS, WATER-BORNE SPRAY (86126)

I

I I ELECTRODEPOSITION (PRIMING ONLY)

I

POWDER COATING I .

I

t

1 I I I I I I I I

6-8
at some of its plants. Because the dip-coated primer is not smooth, the

coating must be sanded or else be used only on areas where appearance is

not important.

Of most interest from a pollution control standpoint is total body

priming by electrophoretic (electrodeposited) water-borne dip. In this

system the object to be coated is immersed in a water-borne coating and

an electric potential difference is induced between the vehicle and the

coating bath. By correctly setting the electrical potential and the

time in the bath, the coating thickness can be controlled as desired.

Corrosion protection is excellent because coverage is more complete than

can ever be obtained by spray priming alone. Additional primer may be

sprayed on rough or sanded areas. This additional primer, called

"surfacer" or "guidecoat", can be either water-borne or organic solvent-

._-.. -

borne.

The paint in the electrophoretic bath consists of 5 to 15 volume

percent solids, 80 to 90 volume percent water, and about 5 volume

percent organic co-solvent. The coating solids displace solvent as they

are deposited and solvent is squeezed out. As the vehicle component

emerges from the bath, its coating is 90 volume percent solids, 9 volume

percent water and 1 volume percent organic co-solvent. Excess coating

is returned to

Because of the

from this oven

the bath by washing with makeup and ultra-filtered water.

extremely low solvent usage (about 7 lb/hr), the exhaust

does not require further emission control unless it

presents an odor problem. The electrophoretic dip process is used at

over 40 percent of U.S. assembly plants and is very widely used in

Europe. 1,5,6,7

6-9
An option suitable for some plants is to spray a water-borne

primer.

Organic solvent-borne primers are usually spray applied. When

using organic solvent-borne spray, 85 to 90 percent of the solvent

evaporates in the booth and flashoff area; the remaining 10 to 15

percent evaporates in the oven.

Water-borne coatings contain relatively small quantities of organic

solvents, principally to improve leveling and gloss. They are less

volatile organics than those from organic solvent-borne coatings and

consequently a lower proportion evaporates in the booth(s) and flashoff

area(s). For water-borne topcoats, the calculations here assume that 50

percent evaporates in the spray booth(s) and flashoff area(s) and 50

percent in the cure area(s). Note that maximum humidity limitations

(for proper curing), the necessity of an adequate air flow at oven

entrance, and avoidance of .explosive mixtures, all affect required oven

exhaust volume for water-borne coatings,

A relatively new system of coatings called "autophoretic" has been

used for frames and parts. This system has been proven for these

applications but has not been applied to primers or topcoats.8,9,10 It

is unknown at this time if the system can be used for parts of the

vehicle that are normally visible.

6.3 Special Considerations

With respect to the coating process, the automobile and light truck

assembly industry has characteristics that make it unique. The companies

involved are large and possess a great deal of expertise in coatings

6-10
(unlike some other companies that coat their products), the entire

process is under their control, and they are free to change coatings,

within the limits of their equipment, (unlike toll coaters that often

have no choice in the coatings they use). These tend to facilitate

control, especially the use of low-solvent coatings. The process can,

and usually does, run at a relatively high percentage of capacity and at

a constant rate-which tends to make contra! more cost-effective. The

industry produces a product that is expensive to inventory, must be

responsive to customer whim, and is available with a large number of

optians and colors. These make frequent color change a necessity and

hence the use of powder coating difficult. The industry has strong

competition from foreign imports , and produces a product that is exposed

to a wide range of climates and is judged critically by its appearance.

These considerations make the use of unproven coatings more difficult.

Special considerations drastically affect the cost of control. To

obtai'n acceptable appearance and coverage on a complex shape sucn as a

car or truck, manufacturers have found it necessary to apply topcoats by

a combination of manual and automatic spray. Multiple applications are

necessary to achieve the necessary thickness, and sufficient time must

be allowed between applications for adequate drying. Sufficient space

also must be provi.ded between vehicles on a moving assembly line to

allow the operator to complete his task. All of these factors cause

spray booths to be as much as several hundred feet long. Because the

booth is occupied, OSHA requires a minimum air velocity away from the

workers to protect them. This requirement is normally met by maintaining a minimum air movement from top to bottom of the booth. This

air flow, in conjunction with the long spjsy booths characteristic of

the industry, results in exhaust volumes of hundreds of thousands of

6-11
cubic feet per ainute. The concentrations of organic vapors range from

50 to ZOO ppm (equivalent to less than 2 percent of the lower explosive

limit, i.e., the LEL) at temperatures of 60°F to 90°F. This combination

of high volume and low concentration makes add-on devices very expensive

for spray booths.

Ovens are not restricted to the same low organic concentrat'ons

since they are not occupied. Their allowable concentrations are governed

by three factors: explosivity limits (usually to less than 25 percent

of LEL), the necessity to maintain adequate air inflow at openings to

prevent escape of oven gas , and the necessity to prevent condensation of

high boiling compounds on the inner surfaces of the oven. Although

improved oven entrance design can help in the future, the problem of

adequate inlet flow presently limits motor vehicle assembly plant ovens

to a maximum of about 10 percent of the LEL.'l The condensation problem

may begin to occur at higher concentrations. 7With many older ovens,

modifications may be necessary to raise the concentrations even to 10

percent of the LEL.

Besides minimizing the size and fuel requirements of the control

equipment, operating ovens at the higher concentrations has the additional

advantage of minimizing the fuel requirements of the oven itself by

decreasing the quantity of makeup air to be heated. The higher temperature and the higher concentration (with correspondingly lower exhaust

flow rates) makes incineration much less costly for an oven than for a

spray booth.

Some special considerations make powder coating difficult. These

are the necessity to change colors often and the desirability of "metallic"

coatings. It would be desirable both from a manufacturing and air

6-12
pollution standpoint to switch colors as seldom as possible. Manufacfacturers would like to schedule many vehicles of one color through the

line in sequence for convenience and to save the paint that must be

purged from spray nozzles each time a color is changed. Unfortunately,

vehicles are built with a large number of available options, of which

color is only one. Air conditioners, power brakes, power steering,

etc., are each installed on a given percentage of the production volume.

Each of these subassembly operations has a production capacity that may

be less than the line speed and each.has a finite storage capacity.

Vehicles are largely built to dealer or customer orders which must be

filled within a limited time. The scheduling of vehicles on the assembly

line is, therefore, constrained by many factors and color change is

often necessary between each vehicle. The capability must exist to

change colors quickly in the booth, or else separate application areas

must be available for each color. Because an assembly plant us:;ally

applies in excess of 15 colors, the latter choice is economically

prohibitive.

Spraying powders of different color in one booth also has problems.

In the conventional spray system, each color is delivered through a

separate hose and the operator manually switches his spray nozzle among

the hoses. The former color is first flushed out of the nozzle with the

new color and then coating with a new color begins. Inertial deposition

is the primary coating mechanism although electrostatic attraction may

assist. Once the coating material strikes the surface it agglomerates

and is not then susceptible to reentrainment. High air velocities are

6-13
maintained in the booth to meet health requirements and to prevent

overspray from one vehicle to another. In contrast to this, powder does

not coalesce: the sole force holding the powder is electrostatic

attraction. Furthermore, the small particle size makes it impractical

to use the high sweep velocities required for worker safety (because of

entrainment). Exhaust velocities must be kept low. These low exhaust

velocities make it necessary to use largely automated coating systems

and require face masks where workers are essential. The low velocities

can result in carryover. Any carryover of coating in a powder system

shows up as discrete specks on a differently colored product since there

is no opportunity for dilution of carryover paint specks as in liquidborne coatings.

Metallic coatings, much in demand for automobiles, obtain their

name from platelets of aluminum added to give a reflective appearance.

In a powder system, the platelets cannot move after application and are

thus set in a random order. The appearance is less aesthetically

pleasing than that achieved with liquid-borne coatings where the platelets

orient parallel to the surface. 4

To date these problems have been an obstacle to the adoption of

powder coatings as topcoats in this industry.

6.4 Available Control Technology

For ease of comparing control technology, a flowchart of a typical

plant is shown in Figure 6-3. As outlined at the beginning of this

section, certain technologies are limited to certain affected facilities

and some will reduce emissions from more than one affected facility

6-14
I PRIME APPLICATION 1

FLOW

RATE,

x 103 scfm

COATINGS,

SOLIDS, b. v. SOLVENT

SOLVENTS, EXHAUST

AND TYPE RATE, Ib/hr

12% SOLUTION

LACQUER

18% OISPERSION

LACQUER

32% ENAMEL

50% ENAMEL

WATER-BORNE

380

170

NEGLIGISLE

262 64 4.5

123 30 1.6

SMALL 40 1.6

r+PRIME

. APPLICATION

(AREAS)

PRIME OVEN I

SOLVENT FLOW SOLVENT FLOW

EXHAUST RATE, EXHAUST

x 103 scfm

RATE,

RATE, Ib/hr RATE, Ib/hr- x 103 scfm

--

---

TOPCOAT APPLICATION

r

t

1 r-J-7 r

--I_- _

TOPCOAT 1

b PRIME b APPLICATION + TOPCOAT

OVEN(S) AREA(S) OVEN(S)

2490 1815 438

FLOW

RATE,

x 103 scfm

25.0

1546 1129 212 15.5

720

340

85

- -

525 127 6.0

248 60 3.4

525 85 3.4

----______

TOPCOAT OVEN

SOLVENT

EXHAUST

RATE, Ib/hr

ASSUMPTIONS: SOLVENT CORRESPONDS TO 50-60 mote percent HEXANE-BENZENE; 85 percent OF EMISSIONS ARE IN APPLICATION AREAIS)

FOR SOLVENT-BORNE COATINGS; 50 percent OF EMISSIONS ARE IN APPLICATION AREA(S) FOR WATER-BORNE TOPCOAT; 30 gallhr OF SOLIDS

ARE APPLIED FOR PRIME COAT; 60 @/hr OF SOLIDS ARE APPLIEO FOR TOPCOAT; APPLICATION AREA EXHAUST AT 100 ppm WAS 0.0228 lb/103

scf; OVEN EXHAUST AT 10 percent OF LEL WAS 0.296 lb/103 scf; ORGANIC SOLVENT DENSITY WAS 6.665 lb/flak FOR WATER-BORNE, percent OF

LEL WAS LOWER.

Figure6.3 Typical plant for assembling intermediate-sized automobiles and light-trucks at rate of 60 per hour. (For

different vehicles, the values would correspond to different production rates.)
(e.g., transition to water-borne coatings will result in reduced emissions

from both the application and curing areas). Some technologies can be

combined (e.g., incineration will further decrease emissions even after

a plant changes to coatings with higher solids content).

Caution must be used in applying the cost estimates below to specific

plants, since retrofitting costs can vary greatly depending on the

specific situation. In some cases the assumptions used herein are for

an almost 'ideal cafe; any deviation will increase the cost. One should

carefully analyze each situation to determine if the assumpt5ons are

valid or the deviations essential (for example the cost of control for a

given amount of organic material is roughly inversely proportional to

concentration but exhaust gases in most ovens are far more dilute than

necessary), The paint usage assumptions can also vary considerably

between plants. '* In all cases, the assumptions (and where poss-lbfe the

effects on costs of different assumptions} are listed, either In this

Section or in Section 4 of Volume I.

The control options described have varying levels of current use in

assembly plants. Water-borne primers are currently used in almost half

of the plants. Water-borne topcoats are being used at two plants and

their use is planned at a third. Incineration of oven exhaust has been

used at a number of. plants. Topcoats with greater than 50 volume

percent solids have not yet been used but this level is being approached.

One compa,ty plans to use topcoats with greater than 70 percent solids

before 1981.25 Incineration or adsorption of spray booth exhaust,

although technically feasible, has not been used at any plant. Carbon

6-16
adsorption of spray booth exhaust would require pilot studies because of

known potential problems. Thus the timetable and cost of compliance are

more uncertain using carbon adsorption than for other methods.

Finally, it should be noted that inclusion of a discussion of a

technology in this report indicates it is technically feasible, that is

that no invention is required for its implementation. No judgement is

made as to its reasonability or advisibility for a given situation, from

a standpoint of either cost or energy.

6.4.1 Option 1 - Electrodeposition of Water-Borne Primer - This option

assumes electrophoretic (electrodeposited or electrocoated) application

of primer to the vehicle. Spraying of water-borne primers is possible,

but it does not achieve the same coverage or lend itself to automation

as well as the electrophoretic method does. Water-borne spray priming

is used at some plants and it is a viable option for many plants. It is

important to evaluate the ratio of organic solvent to solids for spray

primers and the losses due to overspraying to determine the effectiveness of this option.

Achievable Reduction - The amount of organic solvent in an electrophoretic

casting is less than 0.15 lbs per gallon (minus water). However, solvent

emitted from evaporation in the tank and from the "surfacer" used after the

dip increases the overall total to about 1.9 lbs per gallon (minus water).

The percentage reduction achieved by a change to electrophoretic coatings

depends on the original system. For example, if the change is from a 32

volLnre percent solids primer (about 5.3 lbs of organic solvent per gallon

of coating) to electrophoresis (about 1.9 -1bs of organic solvent per gallon

of coating), the reduction is 80 percent.

6-17
Technical Analysis - A description of electrophoretic priming (electrodeposition or electrocoating) is provided in Section 3.3.1 of Volume I.

As discussed earlier, electrophoretic priming requires better precl

of the metal than does an organic solvent-borne primer and it requ i

final rinsing with deionized water before priming.

With an organic solvent-borne system, the assembly line can b e

eaning

res a

stopped overnight, on weekends, or during shift changes and breakdowns.

This is not possible with electrophoretic primer or with other waterborne systems because of the potential for rusting and dirt pick-up (due

to the longer time it stays wet). Thus, vehicles covered with waterborne coatings cannot be left for long periods of time before being

baked and the assembly lines must have the capability of carrying coated

vehicles through the oven after assembly line shutdowns. Accommodations

must also be made for storage of these vehicles or parts until the line

starts up again. This necessity for surge storage areas and independent

conveyor chains for each of the spray booths results in additional

conveyor controls and costs.

,

The major limitation of electrophoretic dip coating is that it can

be used only directly over metal or other conductive surfaces. It is

limited to one-coat applications or primer finishes, and there is a

practical maximum thickness that can be achieved.' A bath can only

contain one color so a separate bath would be necessary for each color.

None of these problems adversely affects the use of electrophoretic dip

for primer, but they do make it unusable for motor vehicle topcoats.

Electrophoretic dip coating is a fully demonstrated technology.13

6-18
A consideration for any control option is natural gas usage. In

electrophoretic dip priming, gas is used in the ovens. Although higher

temperature must be maintained for a longer time period than when

curing conventional primers, organic solvent emissions are far less.

Thus,, required air flow may be reduced (this is limited by the ventillation necessary to keep oven gases from escaping and to remove reaction

products from the oven).4 Unlike organic solvent-borne primer, no dryoff of the body after cleansing is required prior to the electrophoretic

coating, therefore it eliminates f;le? usage for this purpose.

Electrical requirements increase by about 1400 kilowatts by a

switch to electrophoretic coatings. Electrical requirments for applying

the coating are about 1000 amps at 400 volts (400 kilowatts). Ford

reports that their plants use 1500 amps at 200 volts (300 kilowatts).l

Cooling requirements for the bath are about 150 tons of refrigeration,

equivalent to about 1300 kilowatts. Some additional power is a-so

required for the agitation and ultrafiltration steps. Note that io to a

300 kilowatt credit in power usage can be taken because most of the

120,000 to 260,000 scfm exhaust from replaced spray booths is no longer

required. (5 ome spray booths may still be needed for surfacer.)

Depending on climate, this air would have to be heated in the winter,

usualw by natural gas, steam or propane. Finally, there is no increase

in pumping requirements since the circulation in the bath that is

necessary in electrophoretic systems for mixing and water circulation is

offset by elimination of the water which would be required in the spray

booths for collecting particulate,

6-19
In sUmmary, since ar! assembly line aoplyirq organic solvent-borne

primers uses about 12,000 KW of electricity, the 1400 kilowatt increase

caused by electrophoresis represents a 12 percent increase.

Cost of Control Option - The principal disadvantage of electrophoretic

dip priming is its high capital cost. Maintenance costs are equal to or

?ess than those for conventional spray systems and operating labor is

'reduced. More coating is applied per vehicle than when spray is used

because coverage is better but total paint usage is about equal to spray

coating because there is almost no waste.

The installed cost of an electrophoretic system for a typical

vehicle assembly plant would be about $8 million. Costs can, of course,

vary considerably depending on what building alteration and relocation

of existing equipment is necessary. Table 6-1 gives increased operating

costs for electrophoretic primer, based on electricity at $O.O3/KWhr,

interest and depreciation at 12 percent of capital costs, and operation

for 4000 hours per year.

Effects and Limitations - Electrophoretic dip coatings contain amines

that are driven off during the curing step. Some plants have found it

necessary to incinerate the oven exhaust gas to eliminate the visible

emission and malodors associated with these amines. No other adverse

environmental effects appear to result from a change to electrophoretic

dip coatings, and no apparent safety problems exist, assuming normal

industrial procedures are foilowed. The energy impact was discussed

earlier in this section.

6 -21)
TABLE 6-1. INCREASED ANNHAL OPERATING COST

FOR ELECTROPHORETIC DIP PRIMERS COMPARED TO SOLVENT-BORNE PRIFIER

Utilities:

Electricity $.03/kWhr x4000 hrs/vr x 140OKW 168,090

Direct labor: 8hrslshift x 500 shift./.vr

Savings of 3 workers/ shift $15/hr

-180,000a

Interest and

depreciation

12 percent x ~,1,000,000

to 8,000,OOO)

120,000

to 960,000

.-I__

Total increased operating cost --- lQ8,nnn to 948,090 $/yr

aTherd is a net credit for labor cost for electrophoretic dip coating.

The calculation is for the difference between one operator versuq four

in a conventional snrav booth applying organic solvent-borne primer.

bAssuming 20 year life, 10 percent interest.

'The range of values is for different ages of the existing prime line.

The lower value represents the increased total installed cost of an

electrophoretic dip line over an organic solvent-borne orime line for a

plant with an old prime line ready for replacement. The higher value

represents the total installed cost for a plant with a new solventborne prime line.

6-21
6.4,,2 Option 2 - Lower Solvent Primer and Topcoat - This option is the

use of lower solvent (higher solids) organic solvent-borne systems (not

to be confused with "high-solids" coatings discussed in Volume I,

Section 3.3.2). At many of its plants, General Yotors uses lacquers for

the topcoat. Lacquers have very low solids content (~14 volume percent).

Ford, American and Chrysler use topcoat enamels with 22 to 35 percent

solids by volume (~33 to 45 weight percent). Volkswagen expects to use

topcoats with ~70 volume percent solids (80 weight percent) by 1981.25

Current solvent-borne prime coats vary from 26 volume percent4 to 37

volume percent (sealer at new Volkswagen plant). European and Japanese

manufacturers use enamels almost exclusively. 7

This option examines the general effect that raising the solids

content of coatings has on emissions. The choice of 50 volume percent

solids as a base is intended as an example only since any increase in

solids content can dramatically reduce emissions, as shown Figure 6-2.

An obvious improvement would be a change from a low solids lacquer

system to a higher solid enamel system.

Any regulation calling for a minimum solids content should be based

on an average over at least an hour since the solids of different

colors and coatings can vary within a plant. Distinction between weight

percent and volume percent solids is also necessary.

Achievable Reduction - The achievable reduction again depends on both

the old elating and its replacement. For example, the 50 volume percent

coating achieves an 86 percent reduction if it replaces a lacquer with

12 volume percent solids, but only a 53 percent reduction if it replaces

an enamel with 32 volume percent solids. Obviously, even further .

reductions can be achieved if an add-on control device is also installed.

6-22
Technical Analysis - There are no significant changes in operating

requirements necessary to switch to lower solvent coatings. Nozzles

would have to be slightly modified as would procedures for application

and curing, but generally, the same equipment would be used. Oven

exhaust volumes could be reduced considerably, as could the number of

spray booths, if lacquers were replaced with enamels.

There are no unresolved technical problems associated with this

option. At present only General Motors uses lacquer for vehicles, but

ev-Lb. they apply enamel to many of their light trucks and some of their

automobiles. General Motors recently converted their Kansas City

assembly plant from applying lacquers to enamels on a trial basis. 4

Cost of Control Option - Typical capital costs for this option are

difficult to assess because they depend completely on the specific plant

situation. We estimate a change from lacquer to enamel would require a

capital cost (including engineering) of $l,OOO,OOO. (General t?;tors

claims that it would be higher.) Based on a rule of thumb 12 percent of

capital investment, annualized operating costs could be as high as

$lZO.,OOO per year although this would be affected by the lower manpower

required to apply enamels and the increased manpower which would be

needed to repair damaged coatings. 4,14

Effects and Limitations - The chief impact of this option would be on

General Motors (GM) Corporation, the only company still predominantly

using the lacquer system.

The energy required to cure enamels should be less than for lacquers

because of lower exhaust flow rates (since fewer coats are needed, fewer
booths are used and less solvent is evaporated). This potential energy

savings is partially offset by the higher temperature required for

curing enamels.

6.4.3 Option 3 - Carbon Adsorption for Primer and Topcoat Spray Booths -

As discussed in Section 6.2 of this volume, 85 to 90 percent of the

solvent emissions from organic solvent-borne coatings occur in the spray

booth and flashoff area and only about 10 to 15 percent in the ovens.

This option considers installation of carbon adsorbers to control organic

emissions from the spray booths and flashoff areas where it is assumed

85 percent of the emissions occur.

Achievable Reduction - Reductions of greater than 85 percent can be

achieved using carbon adsorption to control emissions from primer and

topcoat spray booths. 15,16,17

Technical Analysis - Spraying processes for topcoats and primers are

subject to the same health-related constraints on concentration because

an operator is required in the booth. Thus the organic concentrations

in the exhaust typically average about 100 ppm and can be lower. Some

areas, such as the booth for two-tone coating jobs, have significantly

lower average concentrations.

There are problems in the application of carbon adsorption for

automotive and light duty truck spray booths. These problems, which

arise from the presence of particulate matter and water miscible organics

iin the inlet stream and from high humidity, are solvable. General

Motors has acknowledged that activated carbon can be effectively used'on

spray booths and ovens to reduce solvent emissions by 90-95 percent if

the carbon adsorption system is properly engineered and regularly maintained. 16,'

6-24
For instance, although excessive particulate matter can reduce carbon

life, spray booths generally already use some type of particulate

control. In smaller booths this may be a panel filter, although in the

more typical larger booths, 95 percent efficient water scrubbers (waterwash booths) are used to give a low particulate concentration level.'

The remaining 5 percent could still have a significant effect on an

adsorber but additional particulate removal can be used if necessary.

Such particulate removal has not been included in cost estimates. A

humidity problem, if any, can be solved by reheat of the gases. About a

lOoF reheat may be necessary to reduce the relative humidity below 80

percent. Solvents that are deleterious to carbon can be avoided. Spray

booth temperatures are too low to degrade cation solvents or vaporize or

break down any of the resins into compounds that can cause problems.

As with any add-on control device, the capital cost is largely

dependent on the flow rate. Generally anything that decreases floti

rates of exhaust will decrease capital and fixed operating cost. Possib

methods of reducing flow rates include reduction of velocities past the

workers (yet remaining in compliance with health requirements) and

le

recirculation of cleaned exhaust air from manned spray areas to unmanned

areas using automatic spray. 14,18 Improved automatic spray machines

under development will enable the use of a wider variety of coatings and

also decreased ventilation. 4Another avenue that might be profitably

explored is to protect workers with breathing masks supplied with an

exterior source of clean air. This would permit reduced exhaust flow

rates limited only by the necessity of providing adequate ventilation to

avoid cross-contamination of vehicles on the line and by health regu6-25
lations. 14 An attractive possibility, especially for users of lacquers,

is to switch to higher solids material to reduce flow rates before

applying carbon adsorption; the lower the flow rate, the lower the

cost.

Questions that have been raised in comments to drafts of this

report as to the validity of the assumptions on which we predicate

carbon adsorption can be satisfactorily answered. There&, of course,

:*a,?+‘ .; ,I".. , ,

&&$, .'.,. ,

" ._l.i

The important factor in assuming a sofwkt for cost estim-tion purposes

is that it be representative of the actual solvents us& (to the greatest

degree possible) in the characteristics important to the control technology

being evaluated. The mixture of hexane and benzene meets these criteria

for carbon adsorption. This mixture was chosen because it represents

the two largest classes of solvents (aliphatic and aromatic hydrocarbons)

used, because the molar volumes of these compounds are representative of

most solvent blends (see Section 3.2.1 of Volume I of this series for

the importance of this), and because cost data were available. The

question of the miscibility of the solvents will be covered in the next

section.

Although carbon adsorption is technically feasible, (i.e., no new

inventions are needed for its implementation), no full-scale installations are presently in operation on automobile or truck assembly plant

pa% sp; ay booths. As noted earlier, pilot studies would be necessary

for use of this technology.

Cost of Control Option - These costs were estimated assuming adsorber

modules, each capable of handling 50,000 cubic feet per minute.. Total

costs for a system would be a multiple of the cost for one. Special

6-26
designs for high volume low concentration flows are possible to lessen

capital costs, but were not investigated for this study.

Three cases are costed in Table 6-2. (Note that although these

estimates include installation, actual costs could be higher for difficult .

retrofit situations. Ford estimates that capital costs would be about

80 percent higher. ") The first is with solvent recovery and no credit

for solvent. The second case, which is for solvent recovery with cred i

as fuel only, is probably the most reasonable assumption for assembly

plants. The third case is credit for the solvent at its solvent value

Assembly plants general ly use multi-component solvents and reuse would

be difficult.4

Impacts and Limitations - Due to the pressure drop associated with gas

flow through a carbon adsorber and the large volumes of air through

spray booths, the electrical requirements for handling air are large.

Steam consumption for desorption is also large because of the laroe

amounts of low concentration gas. (See Section 3.2.1 of Volume I of

this series for details.) Some solvent used in assembly plants are

t

sufficiently water miscible to pose a water pollution problem if regeneration steam is condensed and discharged untreated. 4,14 Many of these

compounds (e.g., alcohols, esters and ketones) are primarily in the

formulation to comply with regulations based on photochemical reactivity

such as contained in the former Los Angeles APCD Rule 66 (now Southern

California Air Pollution Control .District Rule 442). With effective

add-on controls, less expensive water-immiscible solvents could be

employed. Carbon adsorption of these "non-exempt" solvent blends

6-27
TAB'LE 6-2. COST ESTIMATES FOR AUTOMOBILE AND LIGHT TRUCK ASSEMBLY

PLANTS WITH CARBON ADSORPTION FOR TOPCOAT SPRAY BOOTHS AND

FLAS'IOFF AREA?

cost ____-

CASE 1 CASE 2 CASE 3

No credit Fuel value Solvent at

for solvent for solvent solvent prices

b

Capital cost

per 1000 ft3 /min '10,820 10,820 10,820

Total capital

cost, $ x 106 2.7' - lwd 2.7c - 19.6d 2.7c - l?.6d

Annualized

operatiyg cost

per 1000 scfm, $ 4,162 4,003 3,643

Total annualized

operat ng cost,

it

1.0' - 7.3d 0. 9gc - 7.26d fl.?OC - 6.61d

$ x 10

Steam use,

lb/hr x lo3 7C-55d 7C-55d 7C-55d

Cost per ton of

organic removed,$ 1,153 1,110 1,005

'Based on 100 porn of hexane-benzene - 90 percent removal and 5840 hrs per year

ooeration. Correction factors for different operating hours assumptions and

a list of other assumptions can be found in Chapter 4 of Volume I. Note that

costs for condensate stripping [if necessary) are not included.

b

It is very unlikely that recovered organics could be reused as solvents.

'Based on 50 percent solids topcoat (248,000 scfm).

dBased on 12 nercent solids toncoat (1,815,Wo scfm).

6-28
(e.g., toluene and xylene) would be less difficult14 although some

treatment of the condensate might still be necessary. In cases where

such a problem is unavoidable, the uncondensed steam (or hot air if hot

air regenerated ) and solvent can be incinerated together15,16,20,21

or the condensate can be stripped and the miscible solvent disposed of

:'\,I , / :j,,

properly. The size, fuel usage and the cost of this incinerator is many

:I 131G

times less than if incineration were used alone.'21' There will, of course,

i ,, ',

: r-:.' ' j

be extra' costs associated with'*thes'e solutions:" These costs are,"'

' '. .. /',(, ,;:,rl, ..i:,,/

however,"difficult

\.'-I ; c,;; “ ;,': ,' ', /$1 : 1, -,,

to liantify since tt?iy va>y"iith the 'iolvents"ised.

, *_., ‘ I, :i II _,

.i , 3 ,L., *.r: .' -' i ’ :ri;i : ,:.)\‘cJ:, 1

An important factor which mu;i'be'&ns<dered before selecting

carbon adsorption as a means of control is space.

ri ill '~115

The exhaust from

’ ! 11,. I -‘$,J 6” iF$: ; ‘t :; t 4);; r ZI r>iiJ p~~irt?~:~i~r! : :vc, :f~?o; l,r. l;c,cj-f~:, :I: it,%’ .P,

assembly plant topcoat spray booths and flashoff areas may need as many

.r.i >.f . . , r ( 8 a ) < . , $I v: \ I :+.2,: : : r1 ;,I ; 1 f .I): ! ) T if;; ., , .(,I: i 1;:! i,:: "'rk!!;:

as 6 to 37 dual-bed carbon adsorption units in parallel operation. The

I_< ' " ,,

floor area required by the adsorbers would be comparable to that'occupied

r -: ),1 -..,+ . , -1 - -1 , ,, , 1 ,, , .' L'

by the spray booths.

6.4.4 Option 4 - Incineration for Spray Booths

Achievable Reductions - Reductions in volatile emissions of 95 percent

' .;

are achievable with incineration.

_ '. t,, I J !.

'Technical Analysis

I, i-1.;

- The basic requirement for noncatalytic incineration

. : .I -

is to maintain sufficient temperature to combust the gases. For the

cost estimates presented here, an exit temperature of 14OO'F has been

I

assumed. Depending on the solvents used, however, the operator may be

able to lower this somewhat and still achieve sufficient oxidation of

a 3

the organics.

6 -29
Important operating requirements for catalytic incineration are the

'.,-:',rjv*j 25?6-: c i .‘+;‘rl522933n kl,d : i r3 T j(jD ir, yjfjz;T$jbflos c$r;, ?f! ‘j ~JSI~J 59’*:t

necessity to preheat and, periodically clean or replace the catalyst. _ .i: I ,' 7 i E jg:i ‘:o; ma9-)? b+2flSl!fl~~n:j :irjj : 5:; 3z1; f:,\,5pu 2 i rgs jJ.:yi; fj rj3~~

Mon!:ifw-r$ng or periodic testing of the exhaust gases is necessary to

2fi?S~u3 tiSffZ79flr3fli 9d 1ilf3L ,tr19\trOZ b;15 : :-9: fyyUT!ri~9-! Y it\

assure that combustion is complete.

+O ~920q2ib.?nsvi-5.2 sTdi3zirn srij bns bsaqi#yJz sd r163 s:fi2nt?bvG3 sil3 'ICI

Although there are no major technical problems associated with

ldv, :Ai, zi 133c-i9n, ~ni 2ir-U 5 3203 Sri? bn6 C]sEZ!J i9b7 ,gz i? sr!T .y;Y9$37q

incinerating the exwst from spray booths and flashoff areas, the high

(92-iuo:) 30 f rriw 5lSfl-T .k.nLls bsau srsw f!ci?h19ni3ni ?t ff6ri3 229f 25mi.3

flow rates and very low organic vapor concentrations will require huge

,176 23203 529riT . znorfufor 929dj Fijiw be.?gi3ozzS 23203 673x5 90

amounts of fuel. Moreover, the opportunity for more than primary energy

.b9ZU 2Ynsvro2 5rij rktiw yffsv ysd3 93i';ii. y?ifnwp 03 3rusilt?ib ,79veworl

recovery is limited due to inadequate outlet for the large amount of

enif39F92 970i9d bs79bi2noZI sd j~!~~m d>irlw ~oj357 frlhjroqmi ri/i

energy involved.

RIO-It f2LlHiX9 3-u .93f42 ai forfnos ?o 2n6sm 6 26 noijqrozbh nodyE

As with carbon adsorption, anything that lowers flow rates will

\Cnf;m 26 bssn ysm 2669~6 ??od2firT barb zrijood yr;rqa fsozqo3 fng[q yidmeaarj

lower capital costs. With incineration, lower flow will lessen the

5ri-Y * noif-6r9qo rs:rm6q n’r 2Jirw noifq7oab6 nodrfi1 bed-[cub \C 02 3 2~

number of modules and the auxiliary fuel requirement. Incinerators have

bs iqu2:;o fE!ij cj 91d&r6qmo:, !j,d SFuoul ?vd-.ozbb sri~, y,d ?v.t;1~s-f ~js76 -IOC:~

not been used to control spray booths of any kind but this technology Ji ,,I.

has been used in processes with similar exhaust gas"characteristics

. I 1 :.t , . .j “(9," i -J" - L "7' 1'.

-- -. --_ ._-. . ._ _ _-

(e.g., for odors).

related streams since the advantages of electrophoretic dip coatings are ^. _f ., .%I,, i /: ,: .JtJY’l jirfi(-j L ,- :'_..:62;r?dnrjT y-SF..

such that this would likely be the preferred control method of rex?-ng

.., .-i 7.J. .':' i .r.r;: 03 ,? i

emissions from application of the prime coat.

,5r3d a . t2ir.. :7’!q 293.6mi3?s j203

The following three options were considered in estimating the cost ,.": '-*r..J -?~v~w$v .I::+: in ;t’r,gvr..: klrif T;; :c,fbn9q9$ .b9ml;22&

of control.

.I ! -.t;jf.-', _. , ,y ;; -> 'a>/ 9 , : , r :’ 32 bnrj ttjnwsmcri j.krij -7swGr oj 3rd~

1. Option one is use of incineration without heat recovery.

.2c-lspro sl-if

2. Option two is use of incineration with primary heat recovery,

that is preheating of exhaust gases prior to incineration. The

efficiency of heat recovery is 35 percent.

e--. a

il -30
3" Option three is the use of a noncatalytic incinerator with 85

percent efficient primary heat recovery. This option was costed based

on captial costs and fuel and electricity rates given in Reference 22.

Labor cost were assumed to be the same as Option 2 and fuel costs were

reduced. This option is being used on a coil coating line in Wisconsin.

23

Heat recovery efficiencies of up to 90 percent are available.

Cost estimates for these three options are summarized in Table 63.

Secondary heat recovery was not costed as there is no apparent use for

this energy.

Effects and Limitations - Small quantities of oxides of nitrogen will

normally be formed during incineration (from atmospheric N2). If there

are ni,trogen or sulfur-containing compounds present in the waste gas,

higher levels of their oxides may be formed. Halogenated compounds will

form acids upon combustion. The nitrogen oxides are formed primarily at

high temperatures such as found in a burner flame and are thus minimized

with high degrees of heat recovery. Thus, the heat recovery mandated by

cost and energy considerations should minimize nitrogen oxide emissions.

The chief adverse effect of incinerating spray booth exhaust 's

hi,gh energy consumption. This can be reduced through the use of: coatings

with lower solvent content, catalysts, and primary and secondary hcit

recovery. Before requiring incineration for spray booths one should

contact local fire protection agencies for their approval. 4

6.4.5 Option 5 - Incineration for Primer and Topcoat Ovens

Achievable Reductions - Reduct;ons in volatile organic emissions of 95

percent are achievable using catalytic or noncatalytic incineration on

oven exhausts.

6-31
TABLE 6-3. COST ESTIMATES FOR INCINERATION OF EXHAUST FROM j22,24

AUTOMOBILE AND LIGHT DUTY TRUCK ASSEMBLY TOPCOAT SPRAY BOOTHS

costs

Capital cost per

1000 scfm, $

.

T;t;l,;gpltal cost,

Annualized operating

cost per 1000 scfm,$

Total operating cost,

$ x 10

Fuel, Btu/hr x lo6

No heat recovery

C

Catalytic

tion 1

Noncatalytic

6,814 4,985

i.tia-1l.G 1.3"-9.4b

8,674 16,447

I

!18Za-133Zb 494a-361 Zb

Electrical

requirements, kW

Cost per ton of

organics removed, S

j 447"-3262b '34ga-2553b

I

/

/

I

2,jlr; : 4,12o

85 D

F

rcent eff icient

38 percent efficient ri h3ry

Primary heat recovery . heat recovery

Option 2 Option 3

Catalytic Yoncatalytic Noncatal ytic

8,050 6,435 * 8,575

2.0a-14.5b 1.5a-ll.0i' 2.1'-15.5'

7,306 11,578 1,598

?.8a-12.8b 2.9a-21.3b 0.4a-2.6b

,,8a,b-862b'c 314a'c-238Ub'c/ 53a-384b

723"-5280b 71ga-5250b i 64Sa-4715b

1,820

j

I

2,91n a n

1

/

aBased on 50 volume percent solids, 248,OOg scfm from toocoat booth(s).

bBased on 12 volume nercent solids (lacquer), 1,815,OOO scfm from topcoat booth(s).

'Net enerqy usaqe considering recovered energy.

d

Based on 95 nercent removal efficiency.
Technical Analysis - There are no serious technical problems with the

use of incineration for oven exhaust and incineration has been used on

automobile and light truck assembly plant ovens.

Cost of Control Option - The control devices for the topcoat and the

primer ovens Jnlould most likely be separate. Primer ovens have exhaust

rates ranging from 1600 scfm to 4500 and are assumed to operate at 10

percent of the LEL. Topcoat ovens have exhaust rates ranging from 3400

scfm to 25,000 scfm, and are also assumed to operate at 10 percent of

the LEL..

Table 6-4 shows estimated costs for primer and topcoat ovens

operating at 10 percent of the LEL. Table 6-5 shows the cost for 15

percent of the LEL. Note that the exhaust volumes are 33 percent lower

for 15 percent of the LEL for the same solvent volume. The 15 percent

of the LEL case is included to show the benefits of minimizing dilution.

It is important to note that most existing ovens are operated at ;?ss

than 10 percent of the LEL. No cost was assigned to the modificati "1~

necessary to reduce air flow to achieve this concentration, however.

The modifications would vary considerably and it is difficult to estimate

a "typical" cost. Since reduction of exhaust flow has a dramatic effect

on consumption of increasingly scarce and expensive natural gas, this

modification would seem to be mandated, even without. pollution control

considerations.

Effects and Limitations - As illustrated by Tables 6-4 and 6-5, the fuel

consumed by incinerators for ovens need not be excessive if the ovens

operate above 10 percent of the LEL. If ov;L‘ns were operated at

6-33
1 Flow ratea

and option

Capital cost

for prime

oven, 4

\nnual operating cost for

Irime oven,$/yre

Total Annual Total

capital

cost, $e

operating

cost,$/yre

Net energy

:sf:6Btu,hl

Electrical Cost per ton 1

requirements of orga

kWe 8

ic

removed, g/tG:le

Lower

Option 1

Catalytic

Noncatalytic

Option 2

Catalytic

Noncatalytic

Option 3

Catalytic

Noncatalytic

52,800: 23,000 136,000 60,700

31,400' 35,900 132,000 99,200

13

12

.

242

397

79,4O b

a

69,200

28,209

31,000

21 294

18 335 i

71,000b

71,900b

23,990

27,100

204,000 73,000 0.8

157,000 83,700 3.9

182,009 61,354 Negligible

185,009 71,003 Negligible

245

284 8

Higher

Option 1

Catalytic

Noncatalytic

Option 2

Catalytic

Noncatalytic

Option 3

Catalytic

Noncatalytic

98,000b

35,000b

46,200 298,090 237,000 8.8 110 154

81,100 238,000 424,000 39.0 83 277

18,300b

18,000b

54,809 396,000 212,000

67,l'X-l !98,000 311,000

145 133

127 203

182,000 eqliqible 166 118

2?9,000 10.8 166 137

6 .(

aLower flow rate

--

t22,ooo

349,099

--- -.----- ---- ------.- ._--

(50X solids enamel): 1609 scfm_ for orime oven; 3400 scfm for toncoat oven. Higher flow -ate (32":

solids primer and 12% solids lacquer toocoat): 4500 scfm for prime oven; 25,000 scfm for topcoat oven.

bCalculated from data for 50011 scfm using six-tenths rule.

'Recommended fuel rate at 22.6 oercent LEL - credit for recovered enerqy (if any).

d

Based on 95 oercent removal. ePrime and Topcoat

TABLE 6-4. COST ESTIMATES FOR INCINERATION Ot- tXtiAu>~ ur rnia M~VU ,"I "",I.

OVENS FOR AN AUTOMOBILE LIGHT TRUCK ASSEMBLY P%A-fjJ

(AT 10 PERCENT OF THE LOWER EXPLOSIVE LIMIT)
rll,lJ 1 “I cl”,ll ““LII4 ‘ “I\ ,,“ I*“. . . - --- _ --

PLANT (AT 15 PERCENT LOWER EXPLOSIVE LiMIT)L4

_--

F iow T;tt\'

and opt ;nr

-- -.---

Iapital cost

ror pri e

)ven, $6

Total Annual total

capital

cost, $ e

operating

cost, $/yr e

Cost per ton

of organics

removed,$$/tonCf

Lower

Option 1 (No heat recovery)

Catalytic

Noncatalytic

Option 2 (Primary heat

recovery)

Catalytic

Noncatalytic

Option 3 (Primary and

secondary Heat recovery)

Catalytic

Noncatalytic

42,100 106,000 48,600

41,000 106,600 58,800

10.6 195

8'. 2 236

49,000 123,500 42,500

48,800 122,800 48,500

56,700 142,700 42,500

57,400 144,500 44,000

.2 13.3

1.13 12.2

- .67d 16.0

- .13d 16.2

171

195

171

177

Higher

fl.tI 3on ! 'bl, iieat recovery)

CiLal.: I~

NoncatalyLic

Option 2 (Piimary heat

recovery)

CatalyF.ic

Noncatalytic

Option 3 (Primary and

secondary heat recovery)

Catalytic

I.---- Nuncatalytic

122,000 281,000 197,400 9.0

iiF

108

112,000 239,000 254,000 21.5 139

146,000 340,000 147,000 1.5 100 81

126,000 281,000 163,000 8.5 92 89

58

56 -

170,000 400,000 105,000 -5.od 120

158,000 343,000 102,000 -l.Od 122

al.ower Ilow rate: 1,100 scfm for prime oven: 7,2Y qcl,,, for topcoat oven. Higher flow rate: 8,333 scfm for prime

oven ) 16,666 scfm for topcoat oven.

b

Calculated from data for 5nfiOscfm using six-tenths rule.

'Based on 95 percent removal.

d

Recovctred energy is greater than energy input. ePrime and Topcoat
15 percent of the LEL, incinerators can actually save energy by recovery

of the fuel value from the solvents that would have been exhausted.

This energy can displace natural gas or other fuels that otherwise would

be needed for the oven, for metal cleaning, for building heat, or for

other uses in the plant. Note that distiliate oil as well as natural

gas can be used as fuel for noncatalytic incinerators. Incinerators

with higher heat recovery efficiency can be used to minimize fuel usage

even of streams with lower LEL values.

6.4.6 Option 6 - Water-Borne To,pcoats

Achievable Reductions - Reductions in organic solvent emissions of up to

92 percent from topcoat spray booths and ovens are achievable using

water-borne topcoats. The exact reduction depends on both the original

coating and the replacement. If, for example the original coating were

12 volume percent solids lacquer (6.5 lbs of organic solvent per

gallon of coating) and the water-borne had 2.8 lbs of organic solvent

per gallon of coating (as do GM coatings in California), reduction would

be 92 percent. If the original coating were 33 volume percent solids,

reduction would be 70 percent.

Technical Analysis - Water-borne topcoats are currently being used at

two General Motors automobile assembly plants in California on a fullscale basis. Although there can be no argument as to the technical

feasibility of water-borne topcoats, a number of major process modifications

are necessary to retrofit this technology to an existing plant. 435

These are:
1. Lengthening of flash tunnel and ovens - Water-borne coatings

require a longer flash tunnel prior to curing. Temperatures must also

be raised more slowly in order to evaporate the water slowly enough to

avoid pitting the coating. This necessitates longer ovens, which in

turn may force equipment relocations.

2. Cleanliness - Water-borne coatings do not "touch dry" (dry to

the point where the surface can be handled) as quickly as solvent-borne

coatings. Thus they are more susceptible to dirt pick-up. This necessitates filtration of incoming spray booth air. Overhead conveyors may

also be unacceptable because of potential for dropping dirt on newly

painted parts.

3. Humidity and temperature- Because the major solvent being

evaporated is water, proper temperature and humidity conditioning of the

make-up spray booth air is vital. If the humidity is too high or the

temperature too low, the solvent will not dry quickly enough an' the

coating will sag on vertical surfaces. If the humidity is too 1c.r or

the temperature too high, the water will evaporate too rapidly and the

coating will have "orange peel" or pits. Each coating must be formulated for a narrow humidity range, but formulations for different .

humidities (within limits) are possible. Water canbe removed from

incoming air by chemical or mechanical means. The chemical means

involves the use of a hydrosccpic solution. The mechanical means

involves the use of refrigeration cycle. The most economical choice

depends on both the climate and the availability of energy at the plant.

The chemical method is more complex, but requires less energy.

6-37
The chemical method uses steam as its energy source while the mechanical

method uses electricity. Thus, steam availability favors the chemical

choice. Both methods have been used.'

4. Shutduwn - Because of the potential for rusting and dirt pickup, vehicles coated with water-borne coatings cannot be left wet over5. Cleanup - Unlike overspray from organic solvent-borne coating,

water-borne coating overspray does not dry in the air before being drawn

through the particulate collector. Th is causes increased cleanup

problems and costs.

6. Sludge handling - Water-borne coatings do not harden in the

water-wash particulate collectors , sludge handling is more difficult.

7. Corrosion - The pipe commonly used to convey organic solventborne coatings from central mixing areas to the spray booth are not

sui.table for water-borne coatings and must be replaced with a corrosion

resistart material. The lifetime of carbon steel spray booths may also

be lessened when water-borne coatings are used.

8. Maintenance - Maintenance costs will increase because of the

new air conditioning and humidity control systems required.

night or even during shift change. The assembly line must have facilities

for carrying painted vehicles through the following oven after a line

shuts down. Accommodations must also be made for storage of these

vehicles until the line starts up again. These requirements necessitate

surge storage areas and independent conveyor chains for each of the

spray booths with resultant controls and costs.

6-38
9. Repair of coatings - Repair of coatings damaged during assembly

is more difficult than for lacquers but no more difficult than for other

enamels.

Cost of Control Option - The cost of converting to water-borne topcoats

for an existing plant will vary. A major variable will be the age of

the existing coating equipment. If near retirement, it may be better to

build entirely new spray booths and ovens. This was done at one of two

automobile plants which converted to water-borne coatings. In this

case:, costs should be adjusted to give credit for the value of the

improved facilities.

If the coating equipment is still relatively modern, however,

retrofitting will entail lengthening of ovens and modification of spray

booths and conveyors. This was the approach taken at the other automobile plant using water-borne topcoats and is the basis for the cost

calculations presented here. Capital costs for a switch to water-borne

topcoats for the model plant are estimated to be about $20 million.5

For a plant where the entire coating line is replaced, capital COSLS are

about twice this. 5

Incremental operating costs include increased electrical requirements and increased maintenance labor. Coating material costs are

approximately the same. Higher oven temperature causes an increase in

natural gas usage. Annualizea operating costs for the model are given

in Table 6-6.

Effects and Limitations - The effluent water from water-borne coating

processes will require the same treatment methods as that from solventborne systems. The treated effluent is acceptable to sewer authorities

6-39
TABLE 6-6. INCREASED ANNUAL OPERATING COST ESTIMATE: fOR

WATER-BORNE TOPCOATS OVER ORGANIC SOLVENT-BORNE

TOPCOATS

Utilities:

Electricity

Direct labor:

i i

!

i

I

I $,GS/KWhr x 4OOOhrs x 5OODKW $6OGJIOO

I

yr

1

20 additional hrsbhift x

500 shifts/vr $15/hr

Maintenance

Building overhead

I

21 percent x capital costs = $4,200,000

0.21 x $20,000,000

i

i

Taxes and insurance i

Interest and

depreciationa ' J

I I

Total increased

operating cost I

$4,950,00O/yr

aAssuminq a 20 year life and 10 percent interest charge

6-40
at the two California plants now using the coatings. Water-borne

coatings do not precipitate and dewater as well in the overspray collection water as do some other paints and this lack of dewatering

creates an increased solid waste disposal problem.

The additional electrical energy consumption to apply water-borne

coatings is about 5000 KW. Since a typical plant uses about 12,000 KW,

a change to water-borne topcoats increases electrical usage by 42 percent.

6.5 Comparison of Control Options and Conclusions

Prime Line - For prime application and cure, several control measures - -

are applicable. Electrophoretic priming and water-borne surfacer is the

most effective control system. The corrosion advantages of this system

is such that at least one company is replacing their priming systems

with electrophoretic systems as they are ready for replacement. Waterborne spray primer may also be used. Although emission reductions

through increased solids content are more limited than for topcoa.s

(enamels are very widely used), this option is worth consideration since

there is still a substantial range of solids contents used. Incineration

of ovens is effective and not energy intensive but it's benefit is limited

since only 5-15 percent of the solvent evaporates there. Add-on devices

for prime spray booths are technologically feasible but probably would

not be installed because of the advantages of a transition to an electrophoretic

coating.

Topcoat Line - Over two-thirds of uncontrolled emissions from the

coating line come from the topcoat application and cure areas. Considerable

reduction in emissions can be achieved at many plants by increasing the

6-41
solids content. This is especially true for plants using lacquers.

Incineration of an oven exhaust is effective for those emissions and

energy consumption is minor if the resultant heat is recovered, but it

has limited impact since only 5-15 percent of the solvent evaporates

there. Carbon adsorption of spray booth exhaust is technically feasible

but pilot studies are needed to overcome the difficulties. Incineration

of spray booth exhaust is technically feasible but it uses substantial

quantities of energy, even with good heat recovery. Water-borne top-

(coats are proven and reduce emissions considerably, but they are substantial users of electrical energy and require substantial capital investment.

Unlike water-borne electrophoretic dip priming, there are no product

quality advantages to the use of water-borne topcoats.

Generally, different control options require different lead times

to implement and utilize the technology. The consideration of timing

(the time by which reductions are sought) should be included in determining

the degree of control required.

3-42
References

1 .

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

Sussman, Victor, H., Ford Motor Company, Dearborn Michigan.

Letter to James McCarthy in comment to draft of this report.

Letter dated August 6, 1976.

LeBras, L.R., PPG Industries, Pittsburgh, Pa., Letter to

Vera Gallagher in comment to draft of this report. Letter

dated August 13, 1976.

Schrantz, Joe, Hitchcock Publishing Company, Wheaton, Illinois.

Letter to James McCarthy in comment to draft of this report.

Letter dated July 22, 1976.

Johnson, W. R., General Motors Corporation, Warren, Michigan.

Letter to James McCarthy in comment to draft of this report.

Letter dated August 13, 1976.

McCarthy, James, A., U.S. Environmental Protection Agency, Research

Triangle Park, N.C., Report of trip to General Motors assembly

plants in South Gate and Van Nuys, California. Report dated

November 17, 1975.

McCarthy, James A., U.S. Environmental Protection Agency, Research

Triangle Park, N.C., Report of trip to assembly plant in Framingham,

Mass. Report dated November 17, 1975.

Conversation with John Stockholm, St. Gobian Company in Paris,

France, September 20, 1976.

Stockbower, E.A., Amchem Products, Inc., Ambler, Pa. Letter to

James McCarthy in comment to draft of this report. Letter dated

August 2, 1976.

Schrantz, Joe, How Autodeposited Coating Benefits Chrysler.

Industrial Finishing, November 1975, page 14.

Anonymous, "Electroless Electrocoat" Now in Production at Chrysler.

Products Finishing, October 1975, page 72.

Conversation with Fred Portx, Ford Motor Company, Dearborn, Michigan,

September 23, 1976.

12. Johnson, W. R., General Motors Corporation, Warren, Michigan.

Letter to James McCarthy in comment to draft of this report. Letter

dated November 12, 1976.

13. Kalchman, N. C., General Motors Corporation, Warren, Michigan.

Letter to Gerald M. Hansler, Region II U.S. Environmental Protection

kg ocy. Letter dated February 11, 19 1.

6-43
14. Bullitt, Orville H., E. I. DuPont de Nemours & Company, Wilmington,

Delaware. Letter to William Johnson in conanent to draft of this

report. Letter dated August 12, 1976.

15. Sussman, Victor, H., Ford Motor Company, Dearborn, Michigan,

Letter to James McCarthy dated August 6, 1976.

16. Radian Corporation, Austin, Texas, Evaluation of a Carbon Adsorption

Incineration Control System for Auto Assembly Plants. EPA Contract

No. 68-02-1319, Task No. 46, January 1976.

17. Johnson, W. R., General Motors Corporation, Warren, Michigan,

Letter dated to Radian Corporation commenting on Reference 16,

Letter dated March 12, 1976.

18. Roberts, R. W. and J. 6. Roberts, E. I. DuPont de Nemours and Company,

Wilmington, Delaware. An Engineering Approach to Emission Reduction

in Automotive Spray Painting. Presented to 67th Annual Meeting of

the Air Pollution Control Association, Denver, Colorado, June 1974.

Paper No. 74-279.

19. Sussman, Victor H., Ford Motor Company, Dearborn, Michigan ,

Letter to James McCarthy in comment to draft of this report. Letter

dated November 15, 1976.

20, MSA Research Corporation, Package Sorption Device Systems Study.

EPA Contract Report No. EPA-R2-73-202. April 1973.

21. Grandjacques, Bernard, Calgon Corporation, Pittsburgh, Pa., Air

Pollution Control and Energy Savings with Carbon Adsorption Systems,

Report No. APC 12-A. July 18, 1975.

22, Mueller, James H., Reeco, Morris Plains, New Jersey. Letter to

James McCarthy dated October 1, 1976.

23. Inryco, Inc., Melrose Park, Illinois. Inryco's Solution to Paint

Fume Pollution. Inryco Today 1976/2.

24. Combustion Engineering Air Preheater, Wellsville, New York, Report

of Fuel Requirements, Capital Cost and Operating Expense for Catalytic

and Thermal Afterburners, EPA Contract Report No. EPA-450/3-76-031,

September 1976.

25. Volkswagen submittal to Commonwealth of Pennsylvania9 Summer 1976.

644
APPENDIX A
APPENDIX A

ANALYTICAL TECHNIQUES

All analytical techniques used in the determination of compliance

in the surface coating industry have oreviously been published by the

American Society of Testing Materials (ASTM) or the U.S. Government

Suoply Agency. This Aooendix details the applicability and procedures

for using these methods. When used on certain coating products, however,

the methods may yield erroneous results. Therefore, any emission control

regulations which wou!d rely on these methods should also provide authority

for the source to request and the control agency to approve alternative

techniques. During development of such alternatives, the source should be

encouraged to coordinate with ASTM Committee D-l which is responsible for

the three ASTM test methods of interest, numbers D 1644-59, D 1475-60 and

D 2369-73. The procedure that follows yields results in the units of mass

per volume of coating. If units of mass per volume of solids are c'csired,

the source should refer to ASTM test method D X97-73.

A-l
DETERMINATION OF VOLATILE CONTENT OF PAINT, VARNISH,

LACQUER, OR RELATED PRODUCTS

1. Principle and Applicability

1.1 Principle. The weight of nonaqueous volatile matter per unit volume

of a paint, varnish, lacquer, or related surface coating is calculated after

using standard methods to determine the density, nonvolatile matter content,

and (if necessary) water content of the surface coating.

1.2 Applicability. This method is applicable to paint, varnish, lacquer,

and related products, which are air-dried or force-dried; it is not applicable

to any coating system which requires a special curing process such as exposure

to temperatures in excess of 110% to promote thermal cross-linking or exposure

to ultraviolet light to promote cross-linking.

There may be other specific cases where the ASTM methods are not applicable.

In general, these cases will occur when the evaporation temperature is so high

as to produce thermal degradation of the nonvolatile matter in the surface

coating or when the temperature is too low to produce complete evaporation of

the volatile matter. The former will generally be indicated by a discoloration

of the solid residue, while the latter will be indicated by incomplete drying

of the residue (visible liquid or tackiness).

Whenever it is determined that the ASTM methods are not applicable,

alternative methods subject to the approval of the State or local agency, must

be used.

2. Classif'zation of Surface Coatings

For the purposes of this method, the applicable surface coatings are divided

into three classes. They arc:

2.1 Class I: General Solvent-Type Paints. This class includes white

A-2
linseed oil outside paint, white soya and phthalic alkyd enamel, white linseed

o-phthalic alkyd enamel, red lead primer, zinc chromate primer, flat white

inside enamel, white epoxy enamel, white vinyl toluene modified alkyd, white

amino modified baking enamel, and other solvent-type paints not included in

Class II.

2.2 Class II: Varnishes and Lacquers. This class includes clear and

pigmented lacquers and varnishes.

2.3 Class III: Water Thinned Paints. This class includes emulsion or

iatex paints and colored enamels.

3. Applicable Standard Methods

3.1 ASTM D 1644-59 Method A: Standard Methods of Test for Nonvolatile

Content of Varnishes. Do not use Method B.

3.2 ASTM D 1475-60: Standard Method of Test for Density of Paint, Varnish,

Lacquer, and Related Products.

3.3 ASTM D 2369-73: Standard Method of Test for Volatile Content of Paints.

3.4 Federal Standard 141a, Method 4082.1: Water in Paint and Varnishes

(Karl Fischer Titration Method).

4. Procedure

4.1 Classification of Samples. Assign the coating 'to one of the three

classes discussed in Section 2 above. Assign any coating not clearly belonging

to Class II or III to Class I.

4.2 Analyses and Calculations. Determine the density Dm (in g/cm3) of

the paint, varnish, lacquer, or related product according to the procedure

outlined ini ASTM D 1475-60. Then, depending on the class of the coating, use one

of the following specified procedures to determine the volatile content:

A-3
4.2.1 Class I. Use the procedure in ASTM D 2369-73; record the following

information:

w1 = Weight of dish and sample, g.

w2 = Weight of dish and sample after heating, g.

S = Sample weight, g.

Calculate the volatile matter content Cv (in g/l of paint) as follows:

iwl - W2)(Dm)(103)

% = s

To convert g/l to lb/gal, multiply ,C, by 8.3455 x 10e3.

4.2.2 Class II. Use the procedure in ASTM D 1644-59 Method A; record the

following information:

A = Weight of dish, g.

B = Weight of sample used, g.

C = Weight of dish and contents after heating, g.

Calculate the volatile matter content Cv (in g/l) as follows:

c, =

(A + B - C)(Dm)(103)

B

To convert g/l to lb/gal, multiply C, by 8.3455 x 10B3.

4.2.3 Class III. Use the procedure in ASTM D 2369-73; record the same

information as specified in Section 4.2.1. Determine the water content P (in

percentwater) of the paint according to the procedure outlined in Federal

Standard 14'2, Method 4082.1. Calculate the nonaqueous volatile matter content

Cv (in g/l) as follows:

C" =

(w, - w2 - 0.01 PS)(Dm)(103)

S

To convert g/l to lb/gal, multiply Cv by 8.3455 x 10B3.

A-4
5. Bibliography

1. Standard Methods of Test for Nonvolatile Content of Varnishes. In:

1974 Book of ASTM Standards, Part 27. Philadelphia, Pennsylvania. ASTM

Designation D 1644-59. 1974. p. 285-286.

2. Standard Method of Test for Density of Paint, Varnish, Lacquer, and

Related Products. In: 1974 Book of ASTM Standards, Part 27. Philadelphia,

Pennsylvania. AS714 Designation D 14X-60. 1974. p. 231-233.

3. Standard Method of Test for Volatile Content of Paints. In: 1974

Sook of ASm Standards, Part 27. Mladelphia, Pennsylvania. ASTM Designation

D 2369-73. 1974. p. 441-442.

4. Federal Test Method Standard No. 141a. Paint, Varnish, Lacquer, and

Related Materials; Methods of Inspection, Sampling, and Testing. General Services

Administration, Business Service center. Washington, Cl, C. 1965.

A-5
APPENDIX I3

RECOMMENDED POLICY ON CONTROL OF

VOLATlLE ORGANIC COMPOUNDS
ENVIRONMENTAL PROTECTION AGENCY -

Air Quality

RECOMMENDED POLICY ON CONTROL OF

VOLATI LE ORGAN1 C COMPOUNDS

PURPOSE

The purpose of this notice is to recommend a policy for States to

follow on the control of volatile organic compounds (VOC), which are a

constituent in the formation of photochemical oxidants (smog). This

notice does not place any requirements on States; State Implementation

Plan (SIP) provisions which offer reasonable alternatives to this policy

will be approvable. However, this policy will be followed by EPA whenever

it is required to draft State Implementation Plans for the control of

photochemical oxidants.

BACKGROUND

Photochemical oxidants result from sunlight acting on volatile

organic compounds (VOC) and oxides of nitrogen. Some VOC, by their

nature, start to form oxidant after only a short period of irradiation

in the atmosphere. Other VOC may undergo irradiation for a longer

period before they yield measrable oxidant.

In its guidance to States for the preparation, adoption, and

submittal of State Implementation Plans published in 1971, the

Environmental Protection Agency emphasized reduction of total organic

comp:und emissions, rather than substitlltion. (See 40 CFR Part 51;

Appendix B.) However, in Appendix B, EF stated that substitution of

B-l
one compound for another might be useful where it wouTd result in a

clearly evident decrease in reactivity and thus tend to reduce photochemical oxidant formation. Subsequently, many State Implementation

Plans were promulgated with solvent substitution provisions similar to

Rule 66 of the Los Angeles County Air Pollution Control DSstrict. These

regulations allowed exemptQons for many organic solvents which have now

been shown to generate slgnlficant photochemfcal oxidant.

On January 29, 1976, EPA published its "Policy Statement on Use of

the Concept of Photochemical Reactivity of Organic Compounds Jn State

Implementation Plans for Oxidant Control." The notice of availabflity

of this document appeared In the FEDERAL REGISTER on February 5, 1976

(41 FR 5350).

The 1976 policy statement emphasfzed that the reactJvity concept

was useful as an interim measure only, and would not be considered a

reduction in organic emissions for purposes of estimating attainment of

the ambient air quality standard for oxidants. The document also

included the following statement:

Although the substitution portions of Rule 66 and similar

rules represent a workable and acceptable program at the

present time, better substitution regulati.ons can be

developed, based on current knowledge of reactivity and

industrial capability. EPA in collaboration with State

and industry representatives will formulate in 1976 an

improved rule for national use.

SUMMARI

Analysis of available data and information show chat very few

volatfle organic compounds are of such low photochemical reactivity that

they can be Ignored in oxidant control programs. for this reason,

B-2
EPA's recommended policy reiterates the need for positive reduction

techniques (.such as the reduction of volatile organic compounds in

surface coatings, process changes, and the use of control equipment)

rather than the substitution of compounds of low (slow) reactivity in

the place of more highly (.fast) reactive compounds. There are three

reasons for this. First, many of the VOC that previously have been

designated as having low reactivity are now known to be moderately or

highly reactive in urban atmospheres. Second, even compounds that are

presently known to have low reactivity can form appreciable amounts of

oxidant under multiday stagnation conditions such as occur during summer

in many areas. Third, some compounds of low or negligible reactivity

may have other deleterious effects.

Of the small number of VOC which have only negligible photochemical

reactivity, several (benzene, acetonitrile, chloroform, carbon tt rachloride, ethylene dichloride, ethylene dibromide, and methylene cb'oride)

have been identified or implicated as being carcinogenic, mutagenic, or

teratogenic. An additional compound, benzaldehyde, while producing no

appreciable ozone, nevertheless, forms a strong eye irritant under

irradi'ation. In view of these circumstances, it would be inappropriate

for EPA to encourage or suppcrt increased utilization of these compounds.

Therefore, they are not recommended for exclusion from control. Only

the four compounds listed in Table 1 are recommended for exclusion from

SIP regulations and, therefore, it is not necessary that they be inventoried

or controlled. In determining reductions required to meet oxidant

Nb\QS, these VOC should not be included ir :he base line nor should

B-3
reductions in their emission be credited toward achievement of the

NAAQS .

It is recognized that the two halogenated compounds listed in Table

1 (methyl chloroform and Freon 113) may cause deterioration of the

earth's ultraviolet radiation shield since they are nearly unreactive in

the lower atmosphere and all contain appreciable fractions of chlorine.

The Agency has reached conclusions on the effects of only the fully

halogenated chlorofluoroalkanes. The Agency on May 13, 1977 (42 FR

24542), proposed rules under.the Toxic Substances Control Act (TSCA) to

prohibit the nonessential use of fully halogenated chlorofluoroalkanes

as aerosol propellants. The restrictions were applied to all members of

this class, including Freon 113, since they are potential substitutes

for Freon 11, Freon 12, Freon 114, and Freon 115, which are currently

used as aerosol propellants. The Agency is planning to investigate

control systems and substitutes for nonpropellant uses under TSCA, as

announced on May 13. Methyl chloroform is not a fully halogenated

chlorofluoroalkane. Rather, it is among the chlorine-containing compounds

for which the Agency has not completed its analysis; EPA has not yet

concluded whether it is or is not a threat to the stratospheric ozone.

Therefore, it has been placed on this list as an acceptable exempt

compound. As new information becomes available on these compounds, EPA

will reconsider the recommendation.

The volatile organic compounds listed in Table 2, while more

photochemically reactive than those in Table 1, nevertheless do not

contribute large quantities of oxidant under many atmospheric conditions.

B-4
Table 1

Volatile Organic Compounds of Negligible Photochemical

Reactivity That Should Be Exempt From Regulation Under

State Imp1 ementation Plans

Methane

Ethane

*l,l,l-Trichloroethane (Methyl Chloroform)

*Trichlorotrifluoroethane (Freon 113;

*These compounds have been implicated as having deleterious effects on

stratospheric ozone and, therefore, may be subject to future controls.

B-5
Table 2

Volatile Organic Compounds of Low

Photochemical Reactivity

Propane

Acetone

Methyl Ethyl Ketone

Methanol

Isopropanol

Methyl Benzoate

Tertiary Alkyl Alcohols

Methyl Acetate

Phenyl Acetate

Ethyl Amines

Acetylene

N, N-dimethyl formamide

B-6
Only during multiday stagnations do Table 2 VOC yield-significant

oxidants. Therefore, if resources are limited or if the sources are

located in areas where prolonged atmospheric stagnations are uncommon,

priority should be given to controlling more reactive VOC first and

Table 2 organics later. Table 2 VOC are to be included in base line

emission inventories and reductions in them will be credited toward

achievement of the NAAQS. Reasonably available control technology

should be applied to significant sources of Table 2 VOC where necessary

to attain the NAAQS for oxidants. New sources of these compounds will

also be subject to new source review requirements.

Perchloroethylene, the principal solvent employed in the dry

cleaning industry, is also of low reactivity, comparable to VOC listed

in Table 2. It was not included in Table 2 because of reported adverse

health effects. Uses, environmental distribution, and effects o-‘

perchloroethylene currently are being studied intensively by occupational

health authorities and EPA. Findings from these investigations may have

major impact on industrial users. .In designing control regulations for

perchloroethylene sources, particularly dry cleaners, consideration

should be given to these findings as well as industry requirements and

the costs of applying controls. Available control technology is highly

cost effective for large perchloroethylene dry cleaning operations.

However, for coin-operated and small dry cleaners, the same equipment

would represent a heavy economic'burden.

As part of its continuing program, EPA will review new information

relative to the photochemical reactivity, 'oxicity, or effects on

stratospheric ozone of volatile organic cor:Ipounds. Where appropriate,

B-7
additions or deletions will be made to the lists of VOC in Tables 1 and

2 .

DISCUSSION

Most air pollution control regulations applicable to stationary

sources of VOC in the UnSted States are patterned after Rule 66 of the

Los Angeles County Air Pollution Control District (presently Regulation

442 of the Southern California ASr Pollution Control District). Rule 66

and simtlar regulatjons dncorporate two basic strategfes to reduce

ambient oxidant levels, i.e., posl't'ive VOC reduction and selective

solvent substitution based on photochemical reactivity. PosStive

reduction schemes such as inclneratjon, adsorption, and the use of lowsolvent coatings are acknowledged means of reducing ambient oxidant

levels; they should be retained in future VOC control programs. In

contrast, the utility of solvent substitution strategies has been

questioned as more information on photochemical reactivity has emerged.

EPA acknowledged the shortcomings of solvent substitution based on

Rule 66 reactivity criteria in a 1976 policy statement (41 FR 5350).

Findings were cited which indicated that almost all VOC eventually react

in the atmosphere to form some oxidant. Concurrently, EPA inl'tiated an

investigation to consider implications-of revising the solvent substitution

aspect: of Rule 66. Three separate forums were conducted with representatives of State and local air pollution control PJencies, university

professors, and industrial representatives with knowledge and expertise

in the fields of atmospheric chemistry and industrial solvent applications,

In addition, numerous discussions were held with acknowledged experts in

B-8
the field. Topics of particular concern were: *

. Whether Rule 66 substitution criteria could be revised

consistent with available reactivity data and yet be

compatible with industrial processes and with product

requirements.

. Whether some compounds are of sufficiently low reactivity

that they are not oxidant precursors and can be exempted

from contra? under State Implementation Plans.

u Whether the imposition of reactivity restrictions in

addition to positive emission reductions will delay

the development or implementation of promising

technologies, particularly the use of water-borne

and high-solids surface coatings.

Investigation showed that:

1. Solvent substitution based on Rule 66 has been directionally

correct in the aggregate and probably effects some reductions in peak

oxidant levels. However, because of the relatively high reactivity of

most of the substituteo solvents, the reduction is small compared to

that which can be accomplished with positive reduction techniques.

Revision of Rule 66 consistent with current knowledge of reactivity

would eliminate the solvent substitution option for most sources in

which substitution is now employed. Many of the organic solvents which

have been categorized as having low photochemical reactivity are, in

fact, moderately or highly reactive; they yield significant oxidant when

subjected to irradiation in smog chambers Lesigned to simulate the urban

atmosphere.

B-9
2. A few WC yield only negligible ozone when irradiated in smog

chambers under both urban and rural conditions. Experiments conducted

to date indicate that only methane and ethane, a group of halogenated

paraffins, and three other organics --benzene, benzaldehyde, and acetonitrile--can be so classified. These compounds react very slowly yielding

little ozone during the first few days following their release to the

atmosphere. Available data suggest that none of the listed compounds

contribute significant oxidant even during extended irradiation under

multiday stagnation conditions.

The broad group "halogenated paraffins" includes important industrial

solvents, most of which are chlorinated methanes and ethanes and chlorofluoroethanes. They find use as metal cleaning and dry cleaning solvents

and as paint removers. Halogenated paraffins also serve as building

blocks in the manufacture of other halogenated organics; these processes

do not necessarily release significant VOC to the atmosphere.

3. Besides focusing on VOC of negligible reactivity, smog chamber

studies .show that a few additional VOC generate oxidant at a relatively

slow rate. Under favorable atmospheric conditions, these VOC releases

may not form oxidant until they have been transported substantial

distances and become greatly diluted. However, under multiday stagnation

conditions such as occur during summer in many areas of the middle and

eas-tern United States, there is the potential for these organ,ics to

undergo appreciable conversion to oxidant. The more important VOC in

this category are acetone, methyl ethyl ketone, perchloroethylene,

methano1, isopropanol, and propane. All except propane are industrial

B-10
solvents. The latter, a gas under normal conditions,-is associated

principally with crude oil and liquefied petroleum gas operations.

4. The vast number of volatile organic compounds--particularly

nonhalogenated VOC--yield appreciable ozone when irradiated in the

presence of oxides of nitrogen. While there are measurable variations

in their rates of ozone formation, all are significantly more reactive

than VOC listed in Table 2. Quickly reactive VOC include almost all

aliphatic and aromatic solvents, alcohols, ketones, glycols, and ethers.

5. Low photochemical reactivity is not synonymous with low biological activity. Some of the negligible or slowly reactive compounds

have adverse effects on human health. Benzene, acetonitrile, carbon

tetrachloride, chloroform, perchloroethylene, ethylene dichloride,

ethylene dibromide, and methylene chloride have been implicated as

being carcinogens, teratogens, or mutagens. In addition, benzal"?hyde,

which produces no appreciable ozone, nevertheless forms a strong e':e

irritant under irradiation. While their use might reduce ambient oxidant

levels, it would be unwise to encourage their uncontrolled release.

Additional halogenated organics are being investigated for possible

toxicity.

Most of the related health information available at this time

concerns acute toxicity. ThreL.lold limit values (TLV's) have been

developed for many VOC. They are appropriate for the healthy, adult

work force exposed eight hours a day, five days a week. Experts suggest

that more stringent levels should be estab,ished for the general population. Hazards represented by chronic and * ISchronic exposure are much

pls."e di'ficult to quantify than acute toxicity. Adverse health effects

of the VOC cited above are generally recognized although not completely

B-11
quantified. Chlorinated solvents currently are under-intensive study.

6. Some VOC are of such low photochemical reactivity that they

persist in the atmosphere for several years, eventually migrating to the

stratosphere where they are suspected of reacting and destroying ozone.

Since stratospheric ozone is the principal absorber of ultraviolet (UV)

light, the depletion could lead to an increase in UV penetration with a

resultant worldwide increase in skin cancer. The only in-depth analysis

of this potential problem has focused on the chlorofluoromethanes (CFM),

Freon 11 and Freon 12, because of their known stability and widespread

use in aerosol containers. A report of the National Academy of Sciences

concerning environmental effects of CFM's concluded that:

I, . . . selectjve regulation of CFM uses and releases is

almost certain to be necessary at some time and to some

extent of completeness."

"It-1 response to the report of the National Academy of Sciences and other

studies, EPA on May 13, 1977 (42 FR 24542) proposed rules to prohibit

nonessential usage of fully halogenated chlorofluoroalkanes as aerosol

propellants. The restrictions were applied to all members of this class

including Freon 113 since they are potential substitutes for Freon 11,

Freon 12, Freon 114, and Freon 115 which are currently used as aerosol

propellants.

Other stable halogenated solvents which are released in volumes

comparable to the chlorofluoroalkanes also are suspected of depleting

the earth's UV shield. Of major concern is the widesb.-ead substitution

of methyl chloroform (l,l,l trichloroethane) for the photochemically

B-12
reactive degreasing solvent trichloroethylene. Such substitution under

Rule 66 generation regulations has already influenced industrial de&easing

operations to the extent that methyl ch?oroform production has surpassed

that of trichloroethylene in the United States. Any regulation in the

area will have a marked effect on the production and atmospheric emissions

of both solvents. Endorsing methyl chloroform substitution would increase

emissions, particularly in industrial States that have not, heretofore,

implemented Rule 66. On the other hand, disallowing methyl chloroform

as a substitute or banning it altogether would significantly increase

emissions of trichloroethylene even if degreasers were controlled to the

limits of available technology. Presently, technology is only able to

reduce emissions by approximately 50 percent. In metropolitan areas

which have already implemented Rule 66, a return to trichloroethylene

would have an adverse effect on ambient oxidant levels. In addit'on to

being highly reactive, trichloroethylene has been implicated as a

carcinogen.

Alternatives to the above-cited choices would be (1) development

and application,of highly efficient degreaser control systems and (2)

replacement with an intermediate solvent which is neither reactive nor

detrimental to the upper atmosphere. Major revisions would be needed to

degreaser designs to improve vapor capture above the current best level.

.Ailticipated design changes could add materially to degreaser costs. No

alternative solvent is clearly acceptable from the standpoints of

photochemical oxidant and stratospheric ozone depletion. Neither

methy'c;le chloride nor trichlorotrifluoroe iane are reactive, but, like

B-13
methyl chloroform, are suspected of causing damage to-the stratospheric

ozone layer. In addition, methylene chloride is a suspect mutagen.

Perchloroethylene, the principal dry cleaning solvent, does not present

a hazard to the stratosphere but has been implicated as being a carcinogen

and also reacts slowly in the atmosphere to form oxidant.

7. Organic solvents of low or negligible photochemical reactivity

have only limited use in many industries. Most are chlorinated organics

that find principal applications as cleaners for metals and fabrics. A

few nonhalogenated VOC such as acetone, methyl ethyl ketone, and isopropanol

a're of low reactivity but these can't possib1y satisfy all the myriad

needs of the paint, plastics, pharmaceutical, or many other industries.

While users of reactive VOC usually can employ effective control equipment

to recover or destroy VOC emissions, they seldom have the option of

applying reactivity considerations in choosing solvents. AwWng

reactivity restrictions to the surface coating industry would be especially

disadvantageous since it would greatly inhibit the development of lowsolvent coatings; essentially all of the organic solvents used to constitute

high-solids coatings and water-borne coatings are, in fact, highly

reactive.

8. It is recognized that smog chamber studies conducted to date

are incomplete because many organic compounds have not been examined and

it has teen impossible to duplicate a,11 atmospheric situations. For

example, there has been only limited examination of oxidant for,nation

under relatively high ratios of VOC to NO, (3O:l and greater), comparable

toI rural conditions. Any policy on photochemicai reactivity necessarily

B-14
has to be open to revision as new infonnation is devel'oped which may show

specific organic compounds to be more or less photochemically reactive

than indicated by current data.

Dated::

Acting Assistant Administrator

for Air and Waste Management

B-15
APPENDIX C
APPENDIX C

REGULATORY GUIDANCE

1. INTRODUCTION

This section serves to facilitate the preparation of regulations

for the control of volatile organic compound (VOC) emissions from the

surface coating operations discussed in this document. This guidance is

not intended to prescribe specific regulatory language. Responsibility

for developing regulations and the associated emission limitations

clearly rests with the respective States.

2. GENERAL DISCUSSION

The recommended regulatory approach is predicated on the concept of

positive emission reduction rather than the substitution of compounds

ofzlower reactivity as the means of reducing ambient levels of photochemical oxidant. This is in keeping with EPA's recent policy statement on

reactivity.

The facility to be controlled in each of the five coating operations

discussed in this document is the coating line. In general, the recommended

control approach is to reduce emissions from the coating line by means of

low solvent coating technology. This approach is recommended since, in

addition to reducing emissions at the applicator, it also serves to reduce

fugitive .and flash area emissions while at the same time eliminating the

C-l
need for add-on control equipment. It should be recognized, however, that

for certain source categories or coating lines it may be preferable to use

add-on controls, particularly when heat or WC recovery techniques can be

employed. Therefore, the regulations should not preclude the employment

of add-on devices such as incinerators and adsorbers with appropriate

capture systems.

Before developing regulations, States should carefully evaluate the

sources to be regulated within their jurisdiction to determine whether

the emission limitations cited in this document truly reflect reasonably

.

available control technology (FUKT)' for them. In some instances, it may

be found that the guidance is not appropriate for a particular coating

material or coating operation.

The employment of low solvent coatings may be technology forcing for

certain products or applications. Under such circumstances, an extended

time period may be required to evaluate the low solvent coatings both in

the laboratory and the field, prior to placing them into production. In

comparison, the application of add-on control devices is well demonstrated

and ,the only constraint is the time necessary to purchase, install, and

start up such equipment. In view of these factors, compliance schedules

should be flexible, taking into consideration the specific problems

associated with a given plant. Consideration may also have to be given

1

Reasonably available control technology (RACT) is defined as the lowest

emis:sion limit that a particular source is capable of meeting by the

applicaticn of control technology that is reasonably available considering

technological and economic feasibility. It may require technology that

has been applied to similar, but not necessarily identical, sourc?

categories. It is not intended that extensive research and development

be conducted before a given control technology can be-applied to the

source. 'This does not, however, preclude requiring a short-term evaluation program to permit the application of a given technology to a particular type of source.

aspect of RACT.

This latter effort is a legitimate technology-forcing

c-2
to the cumulative impact of other jurisdictions promulgating sIm?!ar

regulations, which may limit the availability of control

equipment, etc.

Even though the regulatory requirements are based on control

technology that has been determined to be reasonably available for the

source category as a whole, some individual plants may not be able to

comply with them. In order to forestall future problems of compliance,

the States should review their various authorities at the time regulations

are developed. If it is found that existing authorities do not provide

sufficient flexibility to accomnodate such problems, consideration should

be given to developing regulatory provisions which will provide adequate

relief.

To assist in developing regulations, the Office of Air Qua1it.y

Planning and Standards (OAQPS) has identified several areas that should

be taken into consideration. These are discussed below.

Comnon Terminology

When developing regulations it is important that a degree of

commonality exists in the definition of key terms. This will provide a

greater degree of understanding on the part of source owners and operators

and remove some of the confusion that presently exists for owners that

have multi-State operations. With this in mind, the following definitions

were developed for commercial an' industrial surface coating operations:

a. Coating applicator means an apparatus used to apply a surface

coating.

b. Oven means a chamber within which heat is used to bake, cure,

polymerize, and/or dry a surface coating.

c. Coating line means one or more apparatus or operations comprised of a coating applicator, flash-off a' ,, and oven wherein a

surface ::qating is applied, dried, and/or CL -1.

c-3
d . Owner or operator means any person who owns, leases, operates,

controls, or supervises a surface coating operation or a

plant of which a sufface coating operation is a part.

Standard conditions mean a temperature of 20°C (68°F) and pressure

of 76i"mn of Hg (29.92 inches of Hg).

f. Volatile organic compound is any compound of carbon (excluding

carbon monixide, carbon dioxide, carbonic acid, metallic carbides or

carbonates, and ammonium carbonate) that has a vapor pressure greater

than 0.1 RRTI of Hg at standard conditions.

9* Day means a 24 hour period beginning at midnight.

h. Capture system means the equipment (including hoods, ducts,

fans, etc.) used to contain, capture, or transport a pollutant to a

control device.

1 . Control device means equipment (incinerator, adsorber, or the

like) used to destroy or remove a pollutant from a discharge gas stream.

j. Approved means approved by the designated air pollution control

official.

Expression of Requirements

When developing regulations, the language used to express the

requirement must be carefully weighed. As noted on page 1-5, the

decision to express emission limitations for coating operations in

terms of weight of VOC per volume of coating, less water, was chosen

after much deliberation. A change in the manner of expression without

an adjustment in the limit could materially affect the stringency of

the requirements. Therefore, if it is found desirable to express the

limitation in different terms, such as pound of VOC per pound of coating

solids, reference should be made to Appendix D so the recorrnnended emission

limit can be properly adjusted.

Similar care must be exercised when specifying requirements for

inciinerators and other add-on control devices. At present, there are

c-4
no standardized test methods that can be universally applied to determine

mass rates of emission or concentrations of VOC. In view of this,

requirements for incinerators and most other add-on devices should be

expressed in terms of efficiency of removing organics expressed as

combustible carbon.

In view of the above, OAQPS developed the following language for

expressing an emission limitation based on the guidance contained in

this document:

"No owner or operator subject to the provisions of this regulation

shall discharge or cause the discharge into the atmosphere from a

coating line any volatile organic compound in excess of poun.ds

per gallon of coating, excluding water, delivered to the coating applicator.

"The emission limit prescribed above shall be achieved by:

a. LOW solvent coating technology,

b. Incineration, provided that 90 percent of non-methane volatile

organic compounds (VOC measured as total carbon) which enter the in,inerator

are oxidized to carbon dioxide and water; or

C . Processing the discharge in a manner determined by control

official to be not less effective than that of b above."

When providing for the use of add-on devices as a means qf

complying with the requirements of the regulation, the States should also

require that such control devices be equipped with an approved capture

system in order to assure effective control. When examining the need for

such a provision, OAQPS staff explored whether it was feasible to prescribe

performance or design specifications for capture systems. After examining

the situation, it was concluded that effective capture systems must be

custom designed to accommodate plant-to-plant variables which affect

performance. An alternative approach of testing to determine whether VOC '

c-5
is escaping capture was also dismissed for the want of suitable testing

techniques. In view of these findings, it is recommended that case-by-case

design review be performed to assure installation of effective capture

systems.

When reviewing capture system designs , air pollution officials must

take into consideration requirements imposed by the Occupational Safety

and Health Administration and the National Fire Prevention Association,

as well as State and local health and safety officials. The publication

"Industrial Ventilation, A Manual of Recormnended Practice" prepared by the

American Conference of Governmental Industrial Hygienists is one source of

guidance on the proper design of capture and ventilation systems.

Need for flexibility

As was discussed earlier, the employment of low solvent coatings

may be technology forcing for certain products or applications. Under

such circumstances-additional time should be afforded sources faced with

real technological problems, provided they move as expediently as practicable toward compliance. During this period it inay be appropriate for

the State to require interim controls such as solvent substitution.

OAQPS does not necessarily recommend the installation of add-on control

devices, particularly incinerators, i f the interim period is to be ofrelatively short duration. In many instances, to do so would be a

disincentive for the source to continue its efforts to develop low

solvent coatings.

An alternate approach that has been the subject of discussion is to

allow the source to develop a plant-wide emission reduction plan. Under

such an approach, the source owner would have to demonstrate that any
emissions in excess of those allowed for a given coating line would be

compensated for. Compensation would be achieved by either reducing VOC

emissions from other coating lines below the allowable level or by

controlling non-regulated sources within the surface coating facility.

The plant-wide emission reduction plan provides flexibility by affording

the source owner the,+ogportunity to select the most cost-effective

means of providing the desired VOC reduction. In addition, it promotes

innovation by encouraging the control of sources that have not been

previously regulated and by providing the source owner an incentive to

control certain coating lines to a greater degree than that required

by the emission limitation. While this approach has been favorably viewed

by industry, enforcement officials have expressed reservations as to its

enforceability. If the problems of enforceability can be overcome, the

plant-wide emission reduction approach would appear to be a very useful

tool.

Seasonal Operation of Natural Gas-Fired Afterburners

As an energy conservation measure, it is also recommended that

provision be made for the seasonal operation of natural gas-fired

afterburners. The basic rationale for seasonal operation of natural

gas-fired afterburners and the criteria for designating time periods

within which the devices may be shut down was set forth in the July 28,

1976, policy statement "Seasonal Operation of Natural Gas-Fired

Afterburners" issued by the Assistant Administrator of Air and Waste

Management (see attachment). The following language is offered if a

State determines that the best method of implementing this policy is by

incorporation into its regulation:

C-7
"The operation of natural gas-fired incinerator and associated

capture systems installed for the purpose of complying with this regulation

will not be required in (specify AQCR) during the month &r months) of

provided that the operation of such devices is not required

for purposes of occupational health of safety or for the control of

toxic substances, malodors, or other regulated pollutants."

Disposal of Waste YOC

Consideration should also be given to restricting the manner by

wtrlch waste valatlle organic cor~ounds are disposed. To accomplish

this objective, QAQPS suggests the followlng regulatory languaw:

*No owner or operator shall dispose of or permft the disposal of

mre than gallons per day of volatile organic cqounds by

any means which will perm5t the evaporation of such compounds to the

.

atmosphere." -

Small Source Exemption

States should also consider for inclusion in their regulation a

provision to exempt certain coating lines from control due to their

small quantity of emissions. When determining which coating lines to

exemp,t, States should assess the sources within their jurisdiction to

determine a lower cut off level which will result in the most effective

control strategy.

Finally, when developing regulations the States should be cognizant

of EPA p3licy statements and other guidance on overall strategy for oxidant

control such as photochemical reactivity, seasonal antroi, and the

Priori-tization of geographical- areas.301 wMch reductions in volatile

organic emissions are required.

C-8
!

ATTACHMENT I

1

f-gfj

y:'p UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

gsiLliz, :!

;

WASHINGTON, D.C. 20460

3

41

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Ha&

JUL 2 8 1376

OFFICE OF

AIR AND WASTE MANAGEMENT

SUBJECT: Seasonal Operation of Natural

Gas-Fired Afterburners

MEMO TO: Regional Administrators

It has been estimated that the use of afterburners for control of

air pollutants required 0.4 percent of the total 22 trillion cubic feet

of natural gas consumed in 1975 in the U.S.. While not a high percentage,

this is a substantial amount of natural gas--equi.valent, for example, to

the annual amount required to heat 62,000.homes in Washington, D.C.

Many of these afterburners are required solely to reduce emissions

of hydrocarbons to control ambient oxidant levels. However, results

from both statistical analyses of ambient data and smog chamber tests

show that oxidants do not readily form at temperatures below about 59°F.

Thus, in many parts of the U.S., the operation of afterburners required

for oxidant control may not be needed during the winter months. This

fact and tZc expectation tnat naturai gas wii i be in =;I”, L =wlJ -‘J ““8’ *Ill-J

the coming winter support an EPA policy of allowing states to permit

natural gas-fired afterburners to be shut down during the coming winter

season rovided there is reasonable assurance that this action will not

jeopardize%i- t e attainment or maintenance of the oxidant standard. The

situation in future winters should be evaluated in light of then-existing

circumstances.

The polfcy applies to gas-fired afterburners installed to control

hydrocarbon emissions for the purpose of reducing ambient oxidant concentration. It does not apply to flares (which do not use gas as an

auxiliary fuel), hydr=rbons vented to boilers, afterburners operated

principally for odor control, or afterburners operated to control toxic

substances. Some afterburners which control hydrocarbon emissions also

control, either primarily or secondarily, the emissions of carbon monoxide

and particulate matter. The seasonal shutoff of some of these also could

be permitted if neither the attainment nor the maintenance of the ambient

standards for those pollutants is jeopardized.

Measurements of oxidant air quality indicate that ambient concentra- -

tions diminish substantially in many northern areas during the winter;

northern urban areas in which summertime oxidant concentrations often

exceed the national standard by large amounts experience greatly reduced

.
canccrttratians during the winter season. lWs &served seasonal pkIXMWWI is consistent with the theory of oti&nt fmmtim; h~~@t ambient

ttmperatures aad stmmg suntight assist is tk pra&cticm of oxidants

fmmaccmplexpttoticheslical' reaMon in~I&ig &r@kmc&mns&

nftrogen 0x3 dies.

Figwe T 3s a Imp of ahe LS. aa k&i& z&u& resms aIs s@z&,.

Xt s.haws general areas (or zones) tn uhkb seas0~4 shot~~ff of matmaP

gas-fired afterbmrs co&d: be considered. %JUWW, it fs imperkant

ta note that locdl conditions may otnf%ate seasonal contrrzl even thvkgh

sbm otk&se may appear tu be acceptable. If, for example, Mntertime oxidant concentratiom in a particular area are in violat$on of

the ambianc star&.!L;, Or‘ th; L~i,XCt~3t~;X f?t ZLffiCi?!??*~ kinh +h?+

afterburner shutdown could create violations, you should nejther encourage

nor allow seasonal afterburner operation even though the area is in a

theoretically acceptab'ie zone.

A policy to seasonally control afterburners can only be implemented

through the SIP process -- by establishing new oxidant SIPS or by revising

existing SIPS. Of course, the enforceabil.ity of the policy must be carefuliy considered in reviewing each specfic regulation. The approval of

SIP changes to permit seasonal afterburner operation need not require

detailed, time-consuming analyses of air quality impacts if the seasonal

shutdown time period is consistent with the zones delineated in Figure. 'I,

and if existing air quality data shows no past violations in the month

during which the afterburners will be shutdown. The attached staff study,

supported by air quality data where available, normally should be adequate

technical support for a decision to approve the seasonal operation of

afterburne-s in a given location. If an occasional high oxidant concentration has been noted during the winter months but the gas savings to be

achieved by afterburner shutoff appears to warrant favorable consideration

+See attached OAQPS "Staff Study: Oxidant Air Quality and Meteorology,"

dated February 6, 1976.
of a variance request, a short trial period to test the impact on oxidant

concentrations may be suggested. If it is found that ambient violations

persist or are exacerbated, the trial program must be terminated.

It is recomnended that you notify those state agencies in your

Region which may be eligible to implement this program that EPA supports a policy which would permit sources to shut off afterburners

during cold weather months this year when oxidant concentrations are

below the ambient standard. In discussing this policy with state agency

personnel 9 it is important to emphasize that the policy pertains only to

oxidant control strategy and that EPA is not encouraging a wide-spread increase in hydrocarbon emissions. Moreover you must make it clear that,

consistent with 9116 of the Clean Air Act, the state is not required in

any way to relax its strategy.

,gsls

#beL

Ro er trelow

Assistant Administrator

for Air and Waste Management

Enclosure

cc: Stan Lear0

William Frick
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+~I:J. Ftgure 1. Areas for' Which the ProbabW ty 'of Maximm Daily Tm$d&ture 3 S96F.b 6% During Monthly Ranges

Indicated (Based on 5 Years of Temperature Data). .
.

. .

STAFF STUDY: OXIDANT AIR QU/JLITY AED KETEOROLOGY

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February 6, 19j6 '

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. Nmitoring and Reports Brmch

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. data bank. Also,.'in some states 'onfy a few monitoricg'site; had

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sufficient data.for 911 quarters orthose stations with sufficient

amounts of data may not have been located krhere maximym concentrations occur. Therefore, because of some deficiencies inherent in

-4

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the air quaiity data base, an additional parameter was used as an

indicator of significant ozone formation potential. This para- .

meter, ma?ir;lilm daily temperature, was used as a surrogate for oxidant/ ,

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' ozone data in areas without such data and as a supple:nsnt in .areas

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_ with insufficient data. High.maximum daily temperatures have been

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Oxidant Air Q~1atl-i ty add ktedrology *

k analysis MS perfo,rmed osf the seasonal: variatton of days

with vfolations of the oxidknt standard at s$tes across fhe n&Son

&th sufficient data for al? $ow qwr”lers o;% I?%%. ~&zp-ixtsd i,n .

~jg,utm?s 2 8fhtYlWg.h. $ are the percent 36 d&G w$fh hOu’rTy GQl%GC%vtra- _

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associated with hi sh ozone concentrations in field and smog chamber

studies.l'* 2* 3 Our best estimate is that nearly all oxidakt/ozowz

concentrations above the NPAQS occur with maximum daily temperatures

.

above about 58-59'F. This was corroborated by an independent analysis of 1973 ozone/oxidant dsta.4 . -

In the current analysis, th-e frequency of maximum daily tenperatlli2: ex&eding 5CoF a'L Selected National Meather Service Sites VJas -

. . . - ___.

,Sabulatcd for-each month over a 5-year climatic period. Assuming that

maximum .da-!ly temperatures above 59'F indicate high ozone formation

potential, the ranges of months that halye less than a 5 percent probaLility of t h i s condition kterc noted. *Since sll days with temperatures.

higher than 59'F will no-i; have all other'conditions (solar radiation,

. air mass characteristics, wind speed, etc.) conducive to formation of

. .

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high ozone concentration, the 5'percent value represents a reasonably -

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. -'- k&f iisk. 'According-19, the geogr%phical areas.meeting this criterion -

.

.-for the two sets of cold month ranges December through February and

November through Ifarch are shown in Figure 1.

. Cons'tdering the analyses of.the.two factors, air quality and .

maximum .daily temperature., the areas of the nation with low seasonal

incidence of, and low potential for NAAQS violations are well defined.

. , The only possible exceptions are the Milwaukee, Wisconsin area and

parts of Massachusetts where oxidant violation frequencies that may

- .

be considered appreciable occur despite the temperature data indicating the contrary during colder months. Pb,sible factors that may

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have caur;cd these anomalies include instrumofitaf errgr, long range

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c

REFEREKES. .

.

1. Bach, tl. D., "Investigation of Ozone and Ozone Precursor

Concentrations at AonWxn Locations in .the Easfcrn L'nitzl Stat.zs,"

Phase fl, Ezsearch Triangle Institute, prepared for Envirorxental

Protection &~rrcy, Research Triangle Pat-k, H. C., EPA Report Ro.

450/3/74-OXa, February 1575.

2. . Lovelace, D. E., Kapsilis, T., Bourke, R. C., and Cools

P. P., *IJ>dianapolis 1974 Suz"ner Ozone Study," 1ndianspoli.s Ceiier

for Advanced Research, Indianapolis, Ind., 1975. .

.3. Jefferies, H. E., Universiti of Not-th Carolina, Chapel

Hi1'1, Personal Comunication to Dinitriades, B., Environaental Protection Agency, Research Triangle Pdrk, N. C., November 1974.

4. Neligan, R. E., Henorandun to Jlalsh, R. T., "High OzoneOxWant Concentrations and Associated Maximum Daily Temperatures

Dirrjng Cold S2ason," Environmental Protection Agency, Research

Triangle Park, fi. C., November 8, 1974 .

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APPENiolX D
APPENDIX D

CONVERSION METHODS

Presented below are techniques which will permit ready conversion

between alternative terms which may be used for emission control

regulations:

l * English Units - Metric Units

a) Multiply Pounds Kilograms

Gallon by 0.12 to get Liter

b) Multiply w by 8.23 to get x

c) Gallons = Liters

Gallon Liter

l o Water-borne coatings, equivalent organic solvent-borne coatings, volume

percent solids, and pounds of solvent per gallon of coating (minus cqter).

a) From volume percent solids in coating, draw vertical line to

appropriate line in Figure D-l (depending on ratio of water to organicsolvent in coating). From the point of intersection, draw a horizontal

line. Where this line intersects the ordinate, read the pounds of solvent

per gallon of coating (min$ water). Where this line intersects the

"Organic-,Borne" line, a vertical line yields the solids content of the

equivalent organic-borne coating. .

b) To convert organic-borne coating to equivalent water-borne, draw

a vertical line in Figure D-l from the volume percent solids to the

"Organic-Borne" line. From this intersectior. <raw a horizontal line.

D-l
Where this intersects the appropriate water-borne line, draw a vertical line

to yield the solids content of the equivalent water-borne coating. The

continuation of the horizontal line yields the pounds of so?vent per

gallon of coating (minus water} of the organic-borne coating and its

equivalent water-borne coating.

e* Wefght percent solids - Volume ~ercmt solids

Dmsfty of Coati= YOJ UUE

Multtply Weight Percent SolIds by Density of Solids- to get Percent

$alids

The density of the solvent may be assumed to be 7.36 pounds per gallon

(0.89 kg per liter) unless better information Is available. the denstty

of the sol$ds may be calculated from the compositfen and density of the

coating:

Density of = (100 x density of coatfng) - (X solvent x 7.36) - (% water x 8.34)

Solids Percent Solids

Densities of coating solids may range from 7 to 35 pounds per gallon

(0.84 to 4.2 kg per liter).

l o Pounds of Solvent per Gallon of Solid - Pounds of Solvent per Pound of Solid

a) Divide Pounds of Solvent by Density of Solid to get

'Gallon of Solid In Pounds Per

Gallon

b) Multiply Pounds of Solvent by Density of Solid to get

Pounds of Solid In Pounds Per

Gallon

Pounds of Solvent

Pounds of Solid

Pounds of Solvent

Pounds of Solid

l o Pounds of Solvent Pounds of Solvent

Gallon of Coating - GalJon of Solld

(minus water)

D-2
FIGURE D-l

I I I I 1 I I I I

sleight of Organic

Solvent Per Gallon for

3 Coatings As A Function

of Solids Content

10 20 30 40 50 60 70 80 90 100

Volume % solids in coating

D-3
90

80

n

Pounds of solvent per gallon

of coating solids

VS’.

Pounds of solvent per gallon

of coating (minus water)

-

-

1 2 3 4 5 t

Pounds of SnlVent Per

(i:!ic:!s wa!xr

allon of coating

.\ ,,
Pounds of solvent per gallon of coating solids

w P ul cn -.I co
r TECHNICAL REPORT DATA

[Please read Inrtnrctiom on the rerwse bcforc cornplctit~~)

REPORT NO. 2 . 3. RECIPIENT’S ACCESSIOFCNO.

EPA-450/Z-77-008

TITLE AND SJBTITLE 5. REPORT DATE

Control of Volatile Organic Emissions from Existing

Stationary Sources-Volume II: Surface Coating of Cans,

M

6. PERFORMING OR

Coils, Paper, Fabric, Automobiles & Light Duty Trucks

AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO.

OAQPS NO. 1.2-073

PERFORMING ORGANIZATION NAME AND ADDRESS

J.S. Environmental Protection Agency

3ffice of Air and Waste Management

3ffice of Air Quality Planning and Standards

iesearch Trianole Park, North Carolina 27711

2. SPONSORING AGENCY NAME AN0 ADDRESS

10. PROGRAM ELEMENT NO.

11. CONTRACT/GRANT NO.

13. TYPE OF REPORT AND PERIOD COVERED

14. SPONSORING AGENCY CODE

5. SUPPLEMENT ARY NOTES

6. ABSTRACT

This report provides the necessary guidance for development of regulations to

limit emissions of volatile organic sources (VOC) of hydrocarbons, especially

from the coating operations of five industries: can, coil, paper, fabric and

automobile and light duty trucks. This guidance includes an emission limit which

represents Reasonably Available Control Technology (RACT) for each bf the five,

analytical techniques for determining the solvent content of coatings, EPA's

policy on the control of VOC, and a monograph on how these components can be used

to develop a State regulation.

r. KEY WORDS AND DOCUMENT ANALYSIS

DESCRIPTORS ~.IDENTIFIERS/OPEN ENDED TERMS c. COSATI Iyield/Group -

-__ -

Air Pollution

Cm, Coil, Paper, Fabric, Automobile and

Light Duty Truck Industries

Air Pollution Control

Solvent Substitution Stationary Sources

Organic Vapors

Emission Limits

Regulatory Guidance i

9. DlSTRlBUTl’DN STATEMENT 19. SECURITY CLASS (7’hi.v I<qmrt) 21. NO. 01 t’Ac,i 7

Unlimi,ted

Unclassified 232

-___- -__ -. ..-. --- -..

20. SECURITY CLASS (Thispup) 22. I’RICF

Unclassified

EPA Form 2220-11 (9-73) .
ENVIRONMENTAL PROTECTION AGENCY

Technical Publications Branch

Office of Administration

Research Triangle Park, North Carolina 27711

OFFICIAL BUSINESS

AN EQUAL OPPORTUNITY EMPLOYER

:

POSTAGE AND FEES PAID

ENVIRONMENTAL PROTECTION AGENCY

EPA. 335

PUBLICATIOjSf NC& I$e. %.