. : : . : : 

BACKGROUND INFORMATION 

FOR 

PROPOSED NEW-SOUR.CE 

PERFORMANCE 

STANDARDS: 

e • • • • 

Steam Generators 

lnci'nerators · · 

Portia nd Cement Plants 

Nitric Acid · Plants 

Sulfuric Acid PIQnts 

U.S •. ENVIRONMENTAL PROTECTION AGE~CY 
BACKGROUND INFORMATION 

FOR PROPOSED 

NEW-SOURCE PERFORMANCE STANDARDS: 

Steam Generators 

Incinerators 

Portland Cement Plants 

Nitric Acid Plants 

Sulfuric Acid Plants 

ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Programs 

Research Triangle Park, North Carolina 

August 1971 
Office of Air Programs Technical Report No. APTD-0711 

i i 
CONTENTS 

INTRODUCTION 

TECHNICAL REPORT NO. 1 - STEAM GENERATORS 

Summary of Proposed Standards 

Particulate Matter 

Sulfur Dioxide 

Nitrogen Oxides 

Emissions from Steam Generators 

Justification of Proposed Standard~ 

Particulate Matter 

Sulfur Dioxide 

Nitrogen Oxides 

Economic Impact of Proposed Standards 

Particulate Matter .. 

Sulfur Dioxide 

Nitrogen Oxides 

References 

TECHNICAL REPORT NO. 2 - INCINERATORS 

Summary of Proposed Standards 

Emissions from Incinerators . 

Justification of Proposed Standards 

Economic Impact of Proposed Standards 

References 

TECHNICAL REPORT NO. 3 - PORTLAND CEMENT PLANTS 

Summary of Proposed Standards ...... . 

i i i 

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Particulate Matter from Kilns ..... 

Particulate Matter from Clinker Coolers 

Particulate Matter from Other Equipment . 

Emissions from Portland Cement Plants . 

Justification of Proposed Standards . 

Particulate Matter from Kilns and Clinker Coolers 

Particulate Matter from Other Equipment 

Economic Impact of Proposed Standards . 

References ........ . 

TECHNICAL REPORT NO. 4 - NITRIC ACID PLANTS 

Summary of Proposed Standards . . 

Emissions from Nitric Acid Plants . 

Justification of Proposed Standards 

Economic Impact of Proposed Standards 

References . . . . . . . . 

TECHNICAL REPORT NO. 5 - SULFURIC ACID PLANTS 

Summary of Proposed Standards 

Sulfur Dioxide 

Acid Mist ... 

Emissions from Sulfuric Acid Plants 

Justification of Proposed Standards 

Sulfur Dioxide. 

Acid Mist ... 

Economic Impact of Proposed Standards 

References. 

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INTRODUCTION 

This document provides background information on the derivation of the 

proposed new-source performance standards and their economic impact 

on the construction and ooeration of new steam generators, municipal 

incinerators, sulfuric and nitric acid manufacturing facilities, and 

portland cement plants. The proposed standards, published in the 

Federal Register under Title 42 CFR Part 466, are being distributed 

·concurrently with this document. The information presented herein was 

prepared for the purpose of facilitating review and comment prior to 

promulgation of the standards. 

The performance standards were developed after consultation with plant 

owners and operators, appropriate advisory committees, equipment 

designers, independent experts, and Federal departments and age~cies. 

Review meetings were held. with the Federal Agency Liaison Committee 

and the National Air Pollution Control Techniques Advisory Committee. 

The proposed standards reflect consideration of comments provided by 

these committees and by other individuals having knowledge regarding 

the control of pollution from the specific source categories. 

The National Air Pollution Control Techniques Advisory Committee is 

made up of 16 persons who are knowledgeable concerning air quality, air 

pollution sources, and technology for the control of air pollutants. 

The membership includes state and local control officials, industrial 

representatives, university professors, and engineering consultants. 
Members are appointed by the EPA Administrator pursuant to Section 

117 (d), (e), and (f) of the Clean Air Amendments of 1970, Public 

Law 91-604. In addition, persons with specific expertise in the 

respective source categories participated in the meeting of the Advisory 

Committee. 

The Federal Agency Liaison Committee includes persons knowledgeable 

concerning air pollution control practices as they affect Federal 

facilities and the nation•s commerce. The committee is made up of 

representatives of 19 Federal agencies. 

The promulgation of standards of performance for new stationary 

sources under Section 111 of the Clean Air Act does not prevent 

state or local jurisdictions from adopting more stringent emission 

limitations for these same sources. In heavily polluted areas, more 

restrictive standards, including a complete ban on construction, may 

be necessary in order to achieve National Ambient Air Quality Standards. 

Section 116 of the Act provides specific authorization to states and 

other political subdivisions to enact such standards and limitations. 

2 
TECHNICAL RE.PORT NO. 1 -

STEAM GENERATORS 

SUMMARY OF PROPOSED STANDARDS 

Standards of performance are being Proposed for new fossil-fuel-fired 

steam-generating units with a capacity greater than 250 million Btu 

per hour heat input. The proposed standards include emission limitations 

for particulates (inc1udins visible emissions), sulfur dioxide, and 

~itrogen ·oxides. The particulate limits are. based on the EPA sampling 

procedure, which employs a dry filter as well as wet impingement collectors. 

The proposed standards would limit emissions to the atmosphere as follows: 

Particulate Matter 

1. No more than 0.2 pound of particulates per million Btu heat input, 

or 0.36 gram per million calories. 

2. Visible emissions shall not be darker in shade than that designated 

as No. 1 on the Ringelmann Scale or 20 percent equivalent opacity, 

except for 2 minutes in any one hour when emissions may be as 

great as No. 2 on the Ringelmann Scale or 40 percent equivalent 

opacity. 

3 
Sulfur Dioxide 

l. No more than 0.8 pound of sulfur dioxide per million Btu heat 

input, or l .4 grams per million calories, when liquid fossil 

fuel is fired. 

2. No more than l .2 pounds of sulfur dioxide per million Btu heat input, 

or 2.1 grams per million calories, when solid fossil fuel is fired. 

Nitrogen Oxides 

1. No more than 0.20 pound of nitrogen oxides (measured as N0 2) 

per million Btu heat input, or 0.36 gram per million calories, 

when gaseous fossil fuel is fired. 

2. No more than 0.30 pound of nitrogen oxides (measured as N02) 

per million Btu heat input, or 0.54 gram per million calories, 

when.Jiguid fossil fuel is fired. 

3. No more than 0.70 pound of nitrogen oxides (measured as N02) 

per million Btu heat input, or 1.26 grams per million calories, 

when solid fossil fuel is fired. 

The proposed particulate standard is equivalent to a stack concentration 

level of 0.12 to 0.13 grain per standard cubic foot corrected to 15 

percent excess air. To burn most fuel oils (less than 0,10 percent ash), 

no particulate controls would be required. Coal-fired steam generators 

would, however, require high-efficiency particulate collectors. The 

visible emissions standard is compatible with the mass emission limit; 

if particulates are at or below 0.20 pound per million Btu, visible emissions 

normally will be less than 20 percent opacity. 
The proposed S02 limits can be achieved by the use of low-sulfur fuels, 

stack-gas cleaning systems, or combinations of the two. No stack-gas 

cleaning would be required for high-grade coal of 0.7 percent sulfur or 

less, or for fuel oil of 0.8 percent sulfur or less. The corresponding 

stack-gas concentration for coal is 620 ppm and for oil, 440 ppm, both 

referenced to 15 percent excess air. 

The proposed nitrogen oxides standards correspond to 165 ppm for burning 

natural gas, 227 ppm for fuel oil, and 525 ppm for high-grade coal, all 

referenced to 15 percent excess air. 

E!MISSIONS FROM STEAM GENERATORS 

Particulate collectors are common to coal-fired boilers and are sometimes 

used with oil-fired units. Coal-fired steam generators tend to use 

mechanical collectors and electrostatic precipitators of varying efficiencies. 

If coal-fired operations were completely uncontrolled, particulate emissions 

would range from 6 to 10 pounds per million Btu. At most existing installations, emissions range from 1 to 4 pounds per million Btu. Particulates from oil-fired steam generators are seldom controlled except for 

mechanical collectors, which are used chiefly during periods of soot 

blowing. Particulate emissions from uncontrolled oil-fired steam 

generators normally range from 0.04 to 0.06 pound per million Btu, with 

most of the particulates traceable to inorganic ash in the oil. Unless 

the ash content of the oil is excessive (greater than 0.4 percent by 

weight), or unless there is poor combustion, particulate emissions are 

well below the limits of the standard. 

Most state and local regulations limit particulate emissions from coalfired steam generators to a level between 0.10 and 0.80 pound per million 

5 
Btu heat input. A few jurisdiction~ have more stringent restrictions 

for oil-fired equipment. One local agency has established limits for 

all three pollutants (particulates. S02, and NOx) from new steam generators at such a low level that solid and liquid fuel utilization is 

precluded. In most instances, particulate limits that are more restrictive 

than the performance standard of 0.20 pound per million Btu heat input 

are based on American Society of Mechanical Engineers (ASME) testing 

procedures that are different from the specified EPA test method. 

Although no definite correlation between these methods has been 

established, it appears that the proposed new-source standard is 

consistent with a level of about 0.07 pound per million Btu if the 

ASME test procedure is used as the reference test method. Despite 

the numerical difference, both standards require about the same 

degree of control. 

With existing fuel sulfur levels, uncontrolled S02 emissions range 

from 1 to 7 pounds per million Btu. Few existing steam generators 

have stack-gas desulfurization except for the demonstration 

installations on which these standards are based. Several state and 

local regulations limit so2 emissions from combustion sources by 

restricting sulfur in fuels. Stack-gas desulfurization usually can 

be utilized rtt the option of the operator. Fuel sulfur limits of 

0.50 to l .0 percent (0.5 to l .4 pounds per million Btu) have been 

established in a number of areas of the country. 

Most of the steam generators in the United States were not designed 

specifically to reduce nitrogen oxides emissions. Nitrogen oxides 

emissions tend to vary with boiler design, and range from 0.3 to 2.0 

6 
pounds per million Btu. Only a few states and local jurisdictions 

restrict NO emissions. 

X 

Limits range from 0.15 to 0.60 pound per 

million Btu heat input for gaseous fuels, and from 0.13 to 0.60 pound 

per million Btu for liquid fuels. These regulations have only recently 

been promulgated, and there has been little experience with their enforcement. The performance standards for gaseous and liquid fuels are 

slightly higher than the minimum levels for local agencies. Regulations 

for oxides of nitrogen produced by solid-fuel combustion have not as 

yet been adopted by states or local jurisdictions. 

In developing performance standards for steam generators, consideration 

was given to the availability and cost of fuels and control techni.ques 

and to effects on the economics of producing electric power. The major 

considerations were: 

The necessity of making use of all the principal fossil fuels - coal.~ 

oil, and natural gas. The cleanest fuels are in limited supply. It 

is estimated that the use of coal will increase at a much greater 

rate over the next 30 years than will that of residual oil and natural 

gas. 

The desirability of setting standards that would allow the use of 

combination control systems to collect both particulates and sulfur 

dioxide. It does not appear that the particulate/S02 systems under 

study are capable ·of collecting nitrogen oxides. 

The desirability of setting sulfur dioxide standards that ''IOuld allm11 

the use of low-sulfur fuels as well as fuel cleaning, stack-~as 

cleaning, and equipment modifications. 

7 
The fact that most low-sulfur fuel oil or crude oil will have to be 

imported from Alaska or from foreign countries. Substantial quantities 

of desulfurized fuel oil will be available from Caribbean facilities, 

several of which will go on-stream in 1971 and 1972. 

The fact that naturally occurring low-sulfur coal is restricted for 

the most part to the Rocky Mountain area, so that shipping costs to 

eastern and midwestern power stations can be appreciable. Coalcleaning techniques can be used to remove substantial portions of 

sulfur and ash from some coals, but the processes are highly dependent 

on the make-up of the coal. 

The fact that stack-gas desulfurization processes have only recently 

been developed to the point at which they can be applied to steam 

generators. The first new steam generators to be affected by the 

standards will be put into operation in 1975 and 1976. In many 

cases owners and operators can delay decisions on a1r pollution control 

equipment for a year or longer after the steam generator has been 

designed. At that time there should be a greater number of options 

for sulfur dioxide control schemes from which to choose. 

JUSTIFICATION OF PROPOSED1STANDARDS 

The proposed performance standards are. based on inspections and tests of 

prototype and full-scale control systems, on consultations with state and 

local officials and operators and designers of steam generators and control 

systems, on EPA surveys of available combustion fuels, and on review of the 

literature. Essentially all of the technology applicable to the subject 

was developed in the United States. 
The adequately demonstrated techniques include the use of electrostatic 

precipitators for particulate removal, low-sulfur fuels and flue-gas 

cleaning for sulfur dioxide removal, and combustion modifications for 

nitrogen oxides abatement. For the most part, these systems have been 

developed independently for each pollutant. The best systems for sulfur 

dioxide and particulate removal have not necessarily been operated on 

the same coal-fired steam generators. Many of the nitrogen oxides control 

techniques have been developed on units fired with low-sulfur fuel oil 

and natural gas, which had no requirements for sulfur dioxide or particulate 

control. 

Particulate Matter 

The particulate limits are based primarily on EPA tests of existing 

electrostatic precipitators that were reported to have high collection 

efficiencies. Seven precipitator-equipped steam generators were tested 

during coal burning using· the EPA test method. Two of the installations 

were shown to meet the particulate limit, and two more barely exceeded 

the limit at 0.21 pound per million Btu. At the most effective precipitators 

only a trace of the emissions was visible. 

Tests of the one 3crubber showed particulate emissions of 0.32 pound per 

million Btu. The marble-bed scrubber, however, was designed principally 

for so2 removal rather than high-efficiency particulate control. Information obtained from various pilot-scale test programs indicates that 

advanced scrubber design~ can achieve the particulate standard of performance. Full-scale scrubbers are now being installed at large steam 

generators. They have been designed to meet particulate levels that are 

consistent with the standard. 

9 
To date no full-scale fabric filters have been demonstrated on coal-fired 

steam generators, although two such units are scheduled to be installed at 

a New Mexico porJer station. Experience with industrial operations would 

indicate that baghouses could be employed to meet the particulate limit of 

the standards. 

The results cited are based on the EPA sampling method, which utilizes a 

dry filter and wet impingement collectors. Most of the data available 

in the literature are based on the American Society of Mechani ca 1 Engineers 

(ASME) test method, which generally reflects lower particulate loadings than 

the EPA method. Reported values with the ASME method range below 0.05 

pound per million Btu for high-efficiency electrostatic precipitators. 

Visible emissions were recorded at the seven coal-fired installations 

where particulates were measured. At the two plants that met the proposed 

standard, as well as at the two steam generators that barely exceeded the 

standard, visible emissions were less than 20 percent opacity. No black 

smoke was observed at any of the tested installations. 

Sulfur Dioxide 

The standards for sulfur dioxide are based on limited demonstrations 

of stack-gas desulfurization processes and on the availability of lowsulfur fuels. At this time only the lime-slurry scrubbing system is 

considered adequately demonstrated on large steam generators. Three other 

processes have been shown capable of continuous operation at smaller 

installations. 

A lime-slurry scrubbing system, demonstrated for 6 months on two coalfired units of 125 and 140 mW capacity, approached the so2 emission limit 

10 
of l. 2 pounds per million Btu. This operation represents 73 percent removal of so2 from fuel gases in instances where the bituminous coal contains 3.0 percent sulfur by weight. One of the units was selected for 

the EPA test program, resulting in a verification of the so2 removal 

pt~rformance reported by the contra 1 sys tern manufacturer and facility 

operator. These lime-slurry systems have been operated at greater S02 

removal efficiency, but only for limited periods, so that sustained 

operation at this level is not considered to have been adequately demon1 strated. A prototype unit, however, employing a dual-bed design, has 

achieved emission levels as low as 1.0 pound per million Btu heat input 

for an extended period of time.2 This system is also apolicahle to steam 

generators burning fuel oil. The demonstrated removal efficiency (76 

percent), applied to a typical fuel oil of 2.5 percent sulfur content, 

results in an emission level of 0.7 pound per million Btu heat input, 

which is below the standard of performance. Lim~-scrubbing systems are 

essentially throwaway processes that produce significant quantities of 

solid waste. For a 3.0-percent-sulfur coal, the additional wastes are 

roughly equal to the ash generated from burning coal. 

Some other processes have been utilized on pilot or prototype installations 

to the point that there is reasonable assurance of successful operation, but 

they are not deemed adequately demonstrated for the purroses of thes~ 

standards. In Sweden, another lime-slurry system, utilizing a different . y.J(Jl' 

scrubber design, has been demonstrated on a 70~Btu-per-hour oil-fired 

unit at emission values of 0.25 pound per million Btu heat input (95 percent 

S02 removal) without interruption of steam generator operation over the 

3 past 3 years. An integrated catalytic-oxidation system has been operated 

at an emission level of 0.5 pound per million Btu heat input during a nrogram 

that accumulated some 7000 hours of operation on coal-generated flue gases 

11 
~ 1 tF" ;:,.. 

with a volumetric flmv rate equivalent to a 120~-Btu-per-hour steam- fJII-f 

electric unit. 4 Sodium sulfite/bisulfite scrubbing has been continuously 

operated at sulfur dioxide removal efficiencies in excess of 90 percent 

on a sulfuric acid plant with a t~il-gas volume flow rate equivalent to a 

220~fBtu-per-hour steam-electric unit. 5 This system has been installed 

t:,S()y. (~ ' !::::1' fl ~1 

at a6Y?OOO,OOO-Btu-per-:-hour oil-fired pm-Jer plant in Japan, which is scheduled 

for operation in late 1971. To date, magnesium oxide-slurry scrubbing has 

been demonstrated only on pilot-scale tests. A full-scale ma~nesium t .. .>')( I !!Jet' 

oxide scrubbing system is being installed to serve a bd ,!~Btu-perhour steam-electric generator and is scheduled for operat1on in October 

1971 . 

Coal and fuel oil of low sulfur content and natural gas can be used to 

satisfy the standards at many new steam generators. It is not expected, 

however, that there will be enough low-sulfur fuel to supply all new steam 

generators as well as existing sources requiring SOz control under state 

implementation plans. In addition, transportation costs in many areas 

may make these fuels more expensive than stack-gas desulfurization. 

Principal sources of low-sulfur crude oil are Africa, Indonesia, Canada, 

and Alaska. Because South American crudes are generally high in sulfur, 

several desulfurization plants have recently been put into operation in 

Central America to satisfy fuel specifications of the eastern United States. 

To ensure reasonable supplies of 0.8-percentssulfur oil to meet the newsource performance standard, some increases in desulfurization capacity 

will be required, as well as growth of low-sulfur imports and extensive 

use of blending. 

11ost of the naturally occurring United States coal of 0.7 n~rcent sulfur 

or less is located in the Rocky Mountain area. Shipping costs have thus 

12 
far precluded widespread use in the midwest and on the east coast. In 

the eastern United States, some coals could be upgraded to meet the standard. 

In other areas that are remote from low-sulfur-coal production sites, however, 

stack-gds cleaning probably will be the least expens1ve method for manv 

operators to meet the standard. 

Nitrogen Oxides 

Nitrogen oxides standards of performance for liquid and gaseous fuels 

were based on tests on units having modifications to the combustion 

process. Combustion modifications of primary importance include fluegas recirculation, off-stoichiometric combustion techniques, low excess 

combustion air, and reduced combustion air preheat. Flexibility in 

application of these methods will be required for compliance with the 

standards of performance. Flue-gas recirculation and off~stoichiometric 

combustion individually have the potential of meeting the standards for 

liquid and gaseous fuels. 

Published test data from six tangentially fired units of~,EOA,?EU to 3.3~(b'f 

1;] !TID Btu per hour ( 320 to 330 mW) capacity utilizing flue-gas tf 

/,;}5VIIJ 

recirculatio~, and from seven units of capacities ranging -lz, ,.., • s- Y.l~ . from ~ase•;:lii'Q 

0;;-7;:ili'$"'t'i Btu per hour (125 to 750 mW) with off-stoichiometric 

combustion techniques, indicate routine operations at or below the required 

emission level of 0.2 pound per million Btu for gaseous fuels. 6•

7 An EPA 

test on one of the six tangentially fired units utilizing flue-gas recirculation verified the published data for these units hurning natural gas and 

fuel oil. Off-stoichiometric combustion is generally utilized to limit 

emissions of nitrogen oxides from steam generators burning liquid fuels. 

/. 3:J. y./tJ" Em~sion s f{om eight oil-fired units ranging in capacity fromj!f, ;36~ 

'1• 81- 0 to~lf ,£1~ Btu per hour (132 to 480 mW) were reported in various 

13 
publications at levels below the standard of performance for liquid 

fuels. 6•

7 Combined methods show promise of much lower emission levels, 

although these techniques have not been adequately demonstrated. 

The NOx standard for solid fuels is based on results from tangentially· 

fired units burning coal. Four tangentially fired units burning bituminous 

coal, which were tested by EPA, had emissions of nitrogen oxides that were 

well below the required level of 0.7 pound per million Btu. Published data 

from numerous sources, and other test results from steam-generator manufacturers, indicate comparable results for tangential firing, and considerably 

higher levels for wall-fired units.7,8 Combustion modifications have not 

as yet been applied to solid-fuel units to any extent. The fact that 

tangential firing alone reduces NOx emissions in units burning coal, however, 

indicates that combustion modifications that have been incorporated in units 

burning natural gas and fuel oil will produce similar reductions with solid 

fuels. In addition, experience gained from gas- and oil-fired un1ts shows 

that there is little difference in NO production between tangentially X 

fired and wall"fired steam generators when combustion modifications ~re 

employed. Emission levels are anticipated to be considerably lower than the 

standard after combined modifications have been instituted. Fuel-constituent 

nitrogen appears to be of secondary importance in the emission of NOx when 

combustion modifications are utilized. 

ECONOMIC IMPACT OF PROPOSED STANDARDS 

Approximately 35 steam-electric generation units and 40 industrial steam 

generators are oresently being installed in the United States annually. 

Some 96 percent of the total capacity of new units greater than 250 

million Btu heat per hour input will be utilized by the electrical utility 
industry. Since construction of steam generators requires from 3 to 

5 years, a substantial portion of the economic impact will be delayed. 

The economics involved with controlling particulate, S02, and NOx 

emissions will vary, depending on the (1) availability of low-sulfur 

fuels in the geographical location, (2) fuel, and (3) control techniques 

selected. The capital investment required to control these three 

pollutants will seldom exceed 25 percent of the total installed cost 

of a steam-electric generation unit. Since units burning gaseous fuels 

need only control NO , the capital investment will amount to only 5 percent X 

of the installed cost. The corresponding increases in operating costs 

for electrical production will range from 15 to 40 percent for solid- and 

liquid-fuel units, and only 4 percent for gaseous fuels. More stringent 

requirements to meet ambient air quality standards as specified by state 

implementation plans (Section 110 of the Clean Air Act) will force control 

costs much higher in some areas. 

Parti cui ate Matter 

The present trend involves the installation of high-efficiency electrostatic 

precipitators of near the same size as those necessary to meet the standard 

of performance. Hence, there is a marginal additional cost resulting from 

the particulate standard. The total costs, however, reflect an allotment 

for an increase of 6 percent in the total capital investment and 4 percent 

in operating costs. These costs exceed those for precipitators alone and 

are high enough to include installation of scrubber systems and baghouses. 

The standard of performance is sensitive to cost/benefit analysis. The 

standard is based on high-efficiency electrostatic precipitators, scrubbers, 

and baghouse collectors. The use of less efficient precipitators and scrubbers 

15 
would require that the standard be relaxed by a factor of 2 with a 

savings of up to 3 percent of the total plant initial investment. 

Sulfur Dioxide 

Control costs for so2 are by far the highest of the three pollutants, with 

increases of about 10 percent in capital investment and 7 to 30 percent in 

operating costs. Sulfur dioxide control is not normally practiced by the 

steam-generation industry and will result in a direct additional cost in 

most areas. The reimbursements for salable by-products, such as elemental 

sulfur and sulfuric acid, were not included as credits in the cost 

estimates because of the market variabilities involved. In addition, the 

cost for disposal of spent reagents incurred by some processes was not considered in any depth. 

The standards of performance are insensitive to cost/benefit analysis when· 

stack-gas cleaning is employed in that it is the only control system 

available. Since the availability of low-sulfur fuel varies with the location 

of the plant, it is not possible to analyze the cost of this control strategy. 

The decision to use low-sulfur fuels instead of flue-gas cleaning may force the 

opening of new mines to meet demand. 

Nitrogen O)(ides 

Nitrogen oxides combustion-modification economics are similar to those 

for electrostatic precipitators, with capital investment increases approaching 7 percent as a maximum, and elevation in operating costs reaching 4 percent. 

The capital investment should decline to 0 percent, however, as combustionmodification becomes common practice and not a special modification. A few 

coal-fired steam generator designs inherently rroduce high levels of NOx, and it 

16 
is unlikely that some of these can be modified to meet the standards. Three 

of the four major steam-generator manufacturers would have to modify their 

coal-fired designs in order to realize the NO limits of the standard. . X 

The fourth manufacturer•s design can meet the standards with no increase 

in cost, however. This manufacturer presently accounts for 40 percent of 

the coal-fired steam-generator market. All four firms sell boilers that 

can meet the limits proposed for gas and oil burning. 

REFERENCES 

1. Martin, J. L., W. C. Taylor, and A. L. Plumley. The C-E Air Pollution 

Control System. Combustion Engineering, Inc. Presented at 1970 Industrial 

' 

Coal Conference, University of Kentucky, Lexington, April 8-9, 1970. 

2. Communication from Combustion Engineering, Inc. Windsor, Conn., 

April 30, 1971. 

3. Bahco Lime Addition- Wet Scrubbing Process. Office of Air Programs 

(internal briefing document), Division of Control Systems, Environmental 

Protection Agency, 1971. 

4. Sites, J. G., Jr. et al. Removing S02 from Flue Gas. Chemical Engineering 

Progress, 65(10):74-79, October 1969. 

5. Communication from Wellman-Power Gas, Lakeland, Fla., April 5, 1971. 

6. Bagwell, F. A., et al. Boiler Operation for Reduced Nitric Oxide 

Emissions. Presented at the 64th Annual Meeting of the Air Pollution 

Control Association, Atlantic City, New Jersey, June 27- July 1, 1971. 

7. Supporting Document on NOx Emissions and Their Control for Steam-Electric 

Boilers. Linden, New Jersey, ESSO Research and Engineering Co., April 1971. 

8. Communication from Combustion Engineering, Inc., Windsor, Conn., 

April 30, 1971. 

17 
TECHNICAl REPORT NO. 2 -

~NCINJIERATORS 

SUMMARY OF PROPOSED STANDARDS 

Standards of performance are being proposed that wiil limit particulate 

emissions from new municipal incinerators with a capacity greater than 

50 tons per day (24-hour). The particulate limits are based on the EPA 

sampling procedure, which employs a dry filter as well as \'let impingement 

collectors. 

The standards of performance would ~pply only to thdse incinerators used 

to burn predominantly municipal solid wastes, e.g., household and commercial 

paper, cardboard, g~rbage, and yard wastes. The standards will not apply 

to incinerators used exclusively to burn sewage sludge, pathological wastes, 

sawdust, or other specialized trade wastes. 

The proposed standard would limit particulate emissions to the atmosphere 

as fo 11 mJs: 

No more than 0.10 grain of particulates per stand~rd cubic foot (scf) 

of dry flue gases, corrected to 12 percent carbon dioxide (C02). 

For burning of typical solid wastes in the United States, the limit of 0.10 

grain per scf, corrected to 12 percent C02, corresoonds to the production 

of 1.9 pounds of particulates per ton of solid wastes charged to the 

19 
incinerator, and about 0.17 pound of particulates per 1000 rounds of flue 

gas, corrected to 50 rercent excess air. 

EMISSIONS FROM INCINERATORS 

An uncontrolled incinerator will emit considerably more particulates than 

the standard allows. Available data indicate that, on the average, uncontrolled furnace gases contain about 1 grain of particulates per scf 

dry gas at 12 percent co2. 1,2 For average domestic solid waste, this 

corresponds to about 19 pounds of particulates per ton of wastes burned .. 

In most cases, these data were obtained using sampling methods different 

from the EPA method that is to be used to determine compliance. Gases 

from existing furnaces, therefore, may contain somewhat more than 1 

grain of particulate matter per scf. The range of 15 to 30 pounds of 

particulates per ton of waste charged probably covers most existing 

incinerators of conventional design. The average particulate collection 

efficiency required to meet the standard is about 90 to 95 percent, based 

on the above uncontrolled emission rate. 

State and local regulations are, in some cases, more stringent than the 

proposed standard. Typical standards range from 0.03 to 0.3 grain per 

scf, corrected to 12 percent C02. Several state and local standards are 

based on particulate test methods that differ from the EPA technique. 

Although no definite correlation between these methods has been established, 

it appears that the proposed standard is not inconsistent with the most 

stringent state- stJndards in existence, which are based on the test procedure of the American Society of Mechanical Engineers. Despite the numerical 

difference, both standards will require approximately the same degree of 

particulate control. 

20 
JUSTIFICATION. OF PROPOSED STANDARDS 

The proposed performance standards are based on a study of incinerators in 

the United States and Europe. -Information was obtained by inspections 

and stack tests of operating plants and by consultation with designers, 

plant operators, and state and local control officials. The Systems Study 

of Air Po 11 uti on from Muni ci pa 1 I ncin.erati on, 1 performed under contract by 

Arthur D. Little, Inc., provided a comprehensive review of American 

operations and incinerator technology. The study showed that almost all 

existing municipal incinerators release excessive amounts of particulates 

and that, until recently, none were equipped with high-efficiency particulate 

collectors. 

Investigations by EPA engineers show that electrostatic precipitators, 

fabric filters, and high-eriergy scrubbers are being utilized to control· 

particulates from municipal incinerators. Tests using the EPA method show 

that particulate emissions from precipitators are within the limits of the 

proposed standard. European tests and pilot studies in this country also 

indicate that fabric filters will provide sufficient particulate control 

to meet the standard. On.one recent installation of a venturi scruhber, 

the designer guaranteed particulate emission levels consistent with the 

prorosed standard. 

21 
Of the approximately 250 municipal incinerators in the United States, only 6 

are equipped with high-efficiency particulate collectors. Five plants have 

electrostatic precipitators, and one is controlled with a high-energy 

venturi scrubber. Two of the domestic precipitators were tested by EPA 

and EPA contractors. Particulate emissions ranged from 0.07 to 0.09 grain 

per scf dry gas, corrected to 12 percent co2. These values were the average 

of three 2-hour sampling runs at each plant. One of the values was confirmed in an independent test in which the EPA sampling method was used. 

At one of the plants, previous tests with· a similar sampling method indicated 

much higher values. Even though the discrepancy has not been explained, 

the EPA results are considered valid. 

Several incinerators in Europe and Japan are equipped with electrostatic 

precipitators designed to achieve an efficiency of better than 99.0 percent in removing particulates. Two European plants, one in Germany 

(with an efficiency of 99 percent) and one in Sweden (with an efficiency 

of 98 percent), were tested by EPA personnel. Emissions averaged, 

respectively, 0.05 and 0.07 grain per scf of dry gas at 12 percent C02. 

The German plant was tested by European methods both before and during 

the EPA tests. Results of all tests - by both European and EPA methods -

are in approximate agreement. 

The U.S. plants tested are of both refractory and water-wall design, 

and capacities range from 300 to 400 tons of municipal refuse per day. 

The European incinerators were of water-wall design, with capacities 

ranging from 220 to 400 tons of municipal refuse per day. 

The few existing data on municipal incinerators equipped with baghouses 

indicate that these devices also could be used to meet the standard. One 

22 
small Swiss unit (36 tons per day) with a fabric filter was tested with 

European sampling procedures; measured values averaged 0.04 grain per scf, 

corrected to 12 percent CO .

3 Lower emissions of particulates are re- 2 . 

ported for a small pilot installation operated by the City of Pasadena 

(California) in 1960. 4 The first large municipal incinerators (greater 

than 50 tons per day) equipped with baghouses will be put into service 

in late 1971 in the United States and Switzerland. 

Test data are not yet available for the one high-energy scrubber in use. 

The venturi scrubber is operated with a 12-inch (water column) pressure 

drop, and it serves a 240-ton-per-day incinerator. The designer has guaranteed 

an emission level consistent with the performance standard. 

ECONOMIC IMPACT OF PROPOSED Sl ANDARDS 

Over the next few years it is estimated that 20 to 25 new municipal 

incinerator furnaces will be constructed annually in the United States. 

The actual rate of construction may vary considerably from this 

estimate depending on the availability of alternative solid waste disposal 

methods. 

In order to meet the limits of the performance standards, new incinerators 

of conventional design will have to be equipped with high-efficiency 

particulate collectors. In addition the incinerators them5elves may 

cost more than many existing units because of the need to provide optimum 

combustion of particulates. Very few existing furnaces are expected to 

be modified to the degree that they will have to comply with the new source 

standard. 

Information on the cost of incinerators and control equipment is derived 

primarily from the cited Arthur D. Little study. 1 Reported costs are 

23 
based on extensive review of manufacturers' quotations, estimated by 

Little to have an accuracy of plus or minus 20 percent, Both total 

installed costs and annual operating costs are presented. Installed 

costs include the incinerator, excavation, foundations, dump pits, 

buildings, and access roads. Annual operating costs include amortization, 

interest, utilities, maintenance, and wages. 

The standard of performance is sensitive to cost/benefit analysis based on 

the use of electrostatic precipitators, scrubbers, or baghouse collectors. 

If the standard were relaxed by a factor ~f 2, capital and operating costs 

of necessary precipitators or scrubbers would be reduced 30 percent. 

Baghouse costs and collection efficiencies are the same regardless of the 

standard. The use of a mechanical collector would require that the 

standard be relaxed by a factor of 4. This would halve capital costs and ()A~M 

sav~$.50 per capita. The benefit of increased particulate control 

warrants the additional expenditure. 

Installed costs for a 100-ton-per-day refractory furnace are about $1 ,000;000 

for the incinerator, including about $150,000 for high-efficiency control 

equipment. Installed· costs of control equipment are therefore about 15 

percent of the entire plant costs. For plants with a capacity of 300 tons per 

day, costs decrease to 13 percent of the incinerator cost. 

For a 100-~n-per-day water-wall furnace, incinerator costs are about 

.# 1.151.10 ' 

$M,53~90~ installed, including about $105,000 for the cost of high-efficiency 

control equipment. Control equipment costs are therefore about 9 percent 

of installed costs for the 100-ton-per-day plant. This decreases to about 

5 rercent for a 300-ton-oer-day plant. 

211. 
The cost of operating the control equipment at the refractory furnace 

plant ranges from $29,000 (100 tons per day) to $65,000 (300 tons per day) 

per year. For the water-wall plant, these costs are $13,000 (100 tons 

per day) and $23,000 (300 tons per day) per year. 

Refuse generation rates as determined by the Office of Solid Wastes 

t1anagement, and equipment costs determined by Arthur D. Little, Inc., were used to 

calculate per capita control costs. Per capita cost varies with incinerator 

design and capacity and with the pollution control equipment employed. 

For the examples developed above, per capita cost is less than about 

l dollar per year, decreasing as furnace capacity increases. 

REFERENCES 

l. Systems Study of Air Pollution from Municipal Inci.neration. Performed 

under Contract No. CPA-22-69-23 by Arthur D. Little, Inc. U. S. DHEW, 

CPEHS, National Air Pollution Control Administration. Raleigh, N.C. 

March 1970. 

2. Duprey, R.L. Comoilation of Air Pollutant Emission Factors. U.S. DHEW, 

PHS. National Center for Air Pollution Control. Durham, N.C. PHS 

Publication No. AP-42. 1968. 67 p. 

3. Private communication \<Jith the European Office of American Air Filter 

Co., Amsterdam, Holland. ,June 1971. 

4. O'Conner, C., and G. Swinehart. Baghouse Cures Stack Effluent. Power 

Engineering 65(5):58-59, 1961. 

25 
TECHNICAL REPORT NO. 3 -

PORTLAND CEMENT PLANTS 

SUMMARY OF PROPOSED STANDARDS 

Standards of performance are being proposed for all new wet- and dryprocess portland cement production facilities. The oroposed standards 

would limit particulate releases. The limits are based on the EPA 

particulate sampling procedure, which includes a dry filter as well as 

wet impingment collectors. 

The emission limitations are summarized as follows: 

Particulate Matter from Kilns 

l. No more than 0.30 pound of particulates per ton of solids fed 

to the kiln, or 0.15 kilogram of particulates per metric ton of 

solids fed to the kiln. The feed rate to the kiln is to be 

expressed on a dry basis. 

2. Visible emissions shall not be darker in shade than that desiqnated 

as No. l/2 on the Ringelmann Scale or 10 rercent equivalent 

opacity. 

Particulate Matter from Clinker Coolers 

1. No more than 0.10 pound of particulates per ton of solids fed 

27 
to the kiln, or 0.05 kilogram of particulates per metric ton of 

solids fed to the kiln. The feed rate to the kiln is to be 

expressed on a dry ba~; is. 

2. Visible emissions shall not be released to the atmosphere. 

Particulate Matter from Other Equipment 

Visible emissions shall not be released to the atmosphere from any 

other areas of the plant, including the raw-material and finishedproduct grinding-mill systems; raw material, clinker, and finished 

product storage facilities; conveyors; transfer points; bagging 

operations; and bulk loading and unloading facilities. For the 

purposes of this standard, visible emissions are considered to be 

any emission of greater than 5 percent opacity, or No. 1/4 Ringelmann. 

This limit is only slightly above the level detectable with the 

human eye. 

The proposed visible emission standards are compatible with the mass 

emission limits for the kiln and clinker cooler; observations have. 

shown that if mass emissions are at or below the respective limits, 

visible emissions will be at or below 10 percent opacity from the kiln 

and no emissions will be visible from the clinker cooler. Observations of the other process equipment - mills, conveyors, etc. - have 

shown that no visible emissions occur if common dust collection equipment 

is installed and properly maintained. 

EMISSIONS FROM PORTLAND CEMENT PLANTS 

Poorly controlled kilns can release as much as 45 pounds of particulates 

to the atmosphere per ton of raw material processed, and poorly controlled 

2.'] 
clinker coolers can release as much as 30 pounds of particulates per toh 

. ,1,2,3 of raw mater1a . Such installations are likely to be equipped only with 

centrifugal dust collectors. The proposed standards would require owners 

and ope~ators of new facilities to reduce the level of particulate 

emissions to 99.3 percent below that of a very poorly controlled kiln 

and 99.7 percent below that of a very poorly controlled clinker cooler. 

At many modern cement plants either electrostatic precipitators or 

baghouses are used to collect dust from the kiln. The kiln is the most 

difficult item in a cement plant to control properly and thus is the 

most likely to be controlled inadequately. Baghouses, electrostatic 

precipitators, and centrifugal collectors are used for control of the 

other process equipment. Baghouses are the most commonly employed 

control devices for mills, conveyors, transfer points, storage silos, 

etc. Many of the dust collectors serve to recover product from exhaust 

gas streams and to increase product yields. Their function as air 

pollution control devices may, therefore, be secondary. 

Many state and local regulations, unlike the proposed standards, allow 

particulate emissions to vary with the rate of input of raw materials. 

For a typical kiln-feed rate of 100 tons per hour, existing state and 

local limits range from 0.32 to 0.90 pound per ton for kilns and from 

0.19 to 0.64 pound per ton for clinker coolers, all of which are higher 

than the proposed standards. A few agencies have adopted stack-gas 

concentration limits comparable to the proposed standards. Because 

some agencies use particulate sampling methods other than the EPA 

method, the limits are not directly comparable. 

29 
JUSTIFICATION FOR PROPOSED STANDARDS 

The proposed performance standards are based on inspections and stack 

tests of existing facilities; consultation with plant operators and 

designers, control equipment manufacturers, and state and local control 

officials; and review of the literature. A principal literature source 

·was a government publication, resulting from a cooperative study 

conducted with representatives of companies manufacturing portland 

cement, entitled Atmospheric Emissions from the Manufacture of Portland 

Cement. 1 

Preliminary investigations revealed the locations of the 12 reportedly 

best~controlled plants in the United States. No information obtained 

indicated that foreign plants were using better technology than the United 

States. Consequently, no foreigri plants were inspected. Twelve United. 

States plants were visited and information was obtained on the process 

and control equipment; judgment was also made as to the feasibility of 

conducting stack tests. Five locations were unsatisfactory because 

control equipment was inadequate or the physical layout of the equipment 

made it impossible to conduct tests (e.g., a pressure baghouse that does 

not have a stack). Stack tests were conducted at seven locations and 

covered four kilns, three clinker coolers, and four raw~material and 

finished-product mills. 

Particulate Matter from Kilns and Clinker Coolers 

Four kilns, as stated, were tested by EPA; corroborative test data were 

obtained from a local air pollution control agency on one of the~EPA 

tested kilns. Results of only three tests were available at the time 

the standards were proposed. Neither of the two wet-process kilns controlled 

30 
with electrostatic precipitators was able to meet the proposed standards. 

A test of a dry-process kiln controlled with a baghouse, however, showed 

particulate emissions of 0.20 pound per ton of feed, which is below the 

proposed standard. Inspections were made of three additio~al kilns 

controlled with baghouses. No visible emissions were produced from the 

latter three kilns, although one wet-proce~s kiln showed a moisturecondensation plume during cold weather. These kilns were not tested 

because of the physical layout of the equipment. 

Three clinker coolers were tested by EPA. The cooler with an electrostatic precipitator and one of the two units with baghouses were shown 

to meet the proposed standard. No visible emissions were observed from 

two additional clinker coolers with baghouses, although they were not 

tested due to the physical layout of the equipment .. 

Investigations confirmed that fabric-filter collectors can be applied to 

both kilns and clinker coolers in conventional wet~ and dry-process portland 

cement production facilities to reduce particulate emissions to the limits 

of the proposed standards. It is possible that electrostatic precipitators 

also can be used to meet the proposed standard for kilns, but such precipitators would have to be more efficient and probably 1 arger than units presently 

installed in existing plants, since tests of the two kilns with electrostatic precipitators showed that neither was able to meet the proposed 

standards. No other particulate abatement schemes have been demonstrated to 

be capable of achieving the standards, although investigations of high-energy 

scrubbing are under way. 

Particulate Matter from Other Equipment 

No emission standards other than visible emission limits have been proposed 

31 
for other equipment in cement plants, such as raw-material mill systems' 

finished-product mill systems, raw-material and finished-product storage 

facilities, conveyors, bagging operations equipment, and bulk loading 

and unloading facilities. The normal industrial practice is to control 

dust from these sources by the use of baghouses, although precipitators 

sometimes are used on finish mills. These devices prevent loss of material 

from the process and reduce air pollution. In most instances, the 

economics of material recovery are sufficient to justify the abatement 

devices without regard to air pollution control regulations. Inspections 

by EPA engineers show that no visible emissions occur from these devices 

when they are properly maintained: Where visible emissions are encountered, 

they are likely to be the result of bag fatlure. 4 

ECONOMIC IMPACT OIF IPROIPOSIEIO STANDARDS 

It is estimated that three new Portland cement kilns and associated 

equipment will be constructed in the U. S. each year and that three 

existing systems will be modified to the extent that they will come 

5 under the proposed standards. 

Many state and local agencies presently have regulations for cement 

plants that require the same types of dust-control equipment mandated 

by the proposed standards. These standards will not result, then, in 

an appreciable increase in the cost of a new cement plant. The only 

significant increase in cost would be to a company that would otherwise 

have constructed a poorly controlled plant in an area not covered _by 

adequate state or local regulations. In any case, the installed 

investment and operating costs of baghouse collectors and electrostatic precipitators cannot be attributed entirely to air pollution 

control because many of the devices are used for product recovery and 

32 
are economically justifiable on that basis. Thus, investment costs 

cannot be computed for air pollution control alone. 

The standard of performance for the kiln is sensitive to cost/benefit 

analysis. The standard is based on a baghouse collector; eiectrostatic 

precipitators are alternative control devices. The use of electrostatic 

precipitators of efficiencies consistent with existing installations 

would require that the standard be relaxed by a factor of 3 with a 

saving of only about 1 percent of total plant investment. More 

efficient precipitators could be installed, but the cost would be about 

1.1 times that of baghouses. The trend in the cement industry is toward 

the use of baghouse collectors, and this trend should be encouraged. 

For a new wet-process plant with a capacity of 2.5 million barrels 

per year (90 tons of feed per hour to the kiln), the total investment 

for all installed air pollution control equipment will represent 

approximately 12 percent of the investment for the total facility. 

The cost of control equipment for the clinker cooler will be 

approximately 10 percent of the cost of all air pollution equipment. 

An electrostatic precipitator or baghouse for the kiln represents 

approximately 60 percent of the cost of all air pollution equipment. 

The remaining 30 percent of the costs will cover dust control for 

the finished-product mill grinding system, conveyors, transfer points, 

storage silos, etc. Annual operating costs for the control equipment 

will be approximately 7 percent of the total plant operating costs if 

a baghouse is used for the kiln, and 5 percent if an electrostatic 

. 't t . d 5,6 prec1p1 a or 1s use . 

33 
For a new plant of 2.5 million barrels per year, ~sing the dry process, 

the total installed investment cost of all air pollution control equipment 

will be slightly higher than 13 percent of the total facility investment 

because additional control equipment will be required for the raw 

material mill grinding system. 6 The operating costs for dry-process control 

will be approximately the same as those for the wet process. 

The impact of the proposed standards on control-equipment manufacturers 

will be small. Because the major manufacturers of control equipment 

offer a complete line (electrostatic precipitators, baghouses, and 

scrubbers), the possible reduction in sales of electrostatic precipitators 

will have little economic impact on manufacturers because the sale of 

baghouses will increase. 

REFERENCES 

1. Kreichelt, T. E., D. A. Kemnitz, and S. T. Cuffe. Atmospheric 

Emissions from the Manufacture of Portland Cement. U.S. DHEW, PHS. 

National Center for Air Pollution Control. Cincinnati, Ohio. 

PHS Publication No. 999-AP-17. 47 p. 

2. McGraw, M. J. and R. L. Duprey. Compilation of Air Pollutant Emissions 

Factors. Preliminary Document. Environmental Protection Agency. 

Research Trian~le P ark, N. C. April 1971. 

3. Guidelines for Control of Emissions from Cem~nt Plants. Internal 

Document. Environmental Protection Agency. Raleigh, N. C. 1970. 

4. Personal communication from R. E. Frey, Vice President, ~ikro Pul, 

Summit, N. J. June 4, 1971. 

5. Elias, J;.R. and J. M. Dement. The Financial Impact of Air Pollution 

34 
Control Upon the Cement Industry. Internal Document. Environmental 

Protection Agency. Raleigh, N. C. February 1971. 

6. Personal communication from D. Stinner, Design Engineer, Fuller Company, 

Catasauqua, Pa. July 9, 1971. 

35 
TECHNICAL REPORT NO. 4 -

NITRIC ACID PLANTS 

SUMMARY Of· PROPOSED STANDARDS 

Standards of performance are being proposed for new facilities producing 

so-called "weak nitric acid" (defined as 50 to 70 percent strength). The 

standards will not apply to the various processes ~sed to produce strong 

acid by extraction or evaporation of weak acid, or by the direct strongacid process. 

The standards of performance are being proposed for total oxides of 

nitrogen and for attendant visible emissions, which are a function of 

nitrogen dioxide concentration. 

The standards would limit emissions to the atmosphere as follows: 

1. No more than 3.0 pounds of nitrogen oxides (NOx) per ton 

of acid produced or 1;5 kilograms NOx per metric ton, 

averaged over a 2-hour period. Acid produced is expressed 

in tons of equivalent 100-percent.strength nitric acid, 

2. Visible air pollutants shall not be released to the atmosphere. 

For a typical weak-nitric acid production facility, the standard of 3.0 

pounds per ton of acid is equivalent to an undiluted stack-gas concentration of 209 parts per million (ppm) by volume. This assumes an exhaust 

volume of 122,000 standard cubic feet (scf) per ton of acid produced. 

37 
EMISSIONS FROM NITRIC ACID PLANTS 

Without control equipment, nitric acid production facilities will 

release about 43 pounds of NOx per ton of acid produced at a concentration of about 3000 ppm NOx (by volume) in the exit gas stream. 

Approximately 50 percent of this emission will be in the form of 

nitrogen dioxide (N02), an opaque reddish-brown gas; the remainder will 

be colorless nitric oxide (NO). The standards would require owners 

and operators of new facilities to reduce NOx emissions to a level 93 

percent below the emissions produced by an uncontrolled facility. 

Of the existing 194 weak-nitric acid production facilities operated 

by government and commercial operators .in the United States in 1971, 1 

only 10 were specifically designed to include NOx abatement, which is 

accomplished by means of decomposition of NOx to elemental nitrogen and 

oxygen. An additional 52 plants, however, were designed to use catalytic 

combustion devices for decolorization and, subsequently, heat recovery. 

The so-ca 11 ed 11 deco l ori zers 11 convert visible N02 to colorless NO with 

the concurrent generation of appreciable heat. -Energy recovered from 

the exhaust gases is used primarily to power the air-compressor turbine 

in the acid process. 

There are no state or local NOx emission regulations in the United States 

that apply specifically to nitric acid production. Ventura County, 

California., has enacted a limitation of 250 ppm NOx that governs njtric 

acid plants as well as steam generators and other sources. 2 

Visible-emission regulations with equivalent opacity provisions also 

restrict nitric acid manufacturing operations in many areas. Never~ 

theless, operators can meet these requirements through the use of 

33 
decolorizer devices, which have little effect on total NOx emissions. 

JUSTIFICATION OF PROPOSED STANDARDS 

The proposed performance standards are based on inspections and stack 

tests of existing facilities; consultations with operators, designers, 

and state and local control officials; and review of the literature. 

In 1962, a cooperative project was initiated by the Manufacturing 

Chemists' Association and the U.S. Public Health Service to study 

emissions from selected chemical manufacturing processes. A goal of 

that program was to publish relevant information in a form helpful to 

control agencies and to the chemical industry. The results of the 

study were subsequently published as Atmospheric Emissions from 

Nitric Acid Manufacturing Processes.3 

Investigations of current nitric acid control technology by EPA engineers 

showed that catalytic decomposition systems can be applied to conventional 

nitric acid production facilities to reduce NOx emissions to levels within 

the limits of the proposed standard. Although alternate techniques are 

under development, no other NOx abatement schemes have been demonstrated 

capable of achieving the standard. 

The catalytic systems are installed downstream of the absorption tower 

at conventional acid-production facilities utilizing the ammoniaoxidation process. Natural gas or hydrogen-rich fuel is burned in the 

gas stream to raise the temperature and to remove excess oxygen orior 

to catalysis. Nitrogen oxides are destroyed in a stepwise process. Initially, 

N0 2 is converted to NO; then the NO is decomposed to nitrogen and oxygen. 

The reactions are exothermic, and reaction products leave the system 

at temperatures as high as 1500°F. Operators recover heat from the 

39 
tail gases. 

A survey of the ten plants in the United States that are equipped with 

the~e systems indicated that five were consistently achieving low NOx 

emission levels. Testing and inspection confirmed that three of the plants 

could be operated well within the performance standard. The other two were 

found to exceed the standard during EPA tests; their emissions were 4.8 and 

8.4 pounds of NOx per ton of acid produced. Both were found to be operating 

with partially deactivated catalyst. Company tests using accepted.test 

procedures indicated that one of the facilities had been achieving an 

average of 2.0 pounds NOx per ton of acid a few months prior to the test. 

At each installation, testing was conducted for about 6 hours on each of 

3 consecutive days. 

Two of the three facilities found to meet the standard burned hydrogenrich purge gas from an adjacent ammonium nitrate plant. The third plant 

.burned natural gas. During the EPA tests, NOx emissions from each of 

the three facilities were consistently lower than the maximum levels of 

the performance standards. Measurements were conducted with continuousNOx-monitoring devices, and values were confirmed by the phenoldisulfonic 

acid method specified in the regulation. 

The nitric acid production facilities on which the tests were conducted 

were of the conventional ammonia-oxidation type of design. They ranged 

in size from 55 to 350 tons per day (24-hour). 

All five of the facilities with catalytic abatement devices were found 

to operate with no visible emissions, which indicated that even the two 

systems with partially spent catalyst were serving as effective decolorizers. 

Although no separate N02 analyses were performed, it appears that most of 

40 
the N02 was converted to colorless NO. Thus, any facility meeting the 

mass NOx limit will produce no visi'ble emissions from the stack. 

ECONOMIC IMPACT OF PROPOSED,STANDARDS 

Based on projections made by nitric acid plant builders and operators, it is 

estimated that construction of new plants will average five facilities per year. 

In considering costs for NOx control, the assumption was made that any new 

nitric acid facility would be equipped with a catalytic decomposition system 

for heat recovery and possible NOx abatement even if NOx limits were not 

imposed. In the absence of any r-egulation on NOx emissions, this unit would 

be operated as a decolorizer and would produce the heat recovery needed to 

drive a process-air compressor. Abatement of NOx requires that all oxygen 

be burned from the tail-gas stream; this is not a requirement for heat 

recovery. Consequently, the fuel used for decolorization and partial abatement is less that that necessary for meeting the proposed standards. 

Furthermore, typical catalysts will become inactive for NOx abatement 

purposes long before they lose their ability to decolorize. 

Th~ standard of performance represents full control and is 1nsensitive 

to cost/benefit analysis. The alternative is essentially no control. The 

standard of performance does not represent a significant increase in the 

capital cost for a new plant, although operating costs will increase as 

the result of increased fuel use and decreased catalyst life. 

Estimates of both capital investment and operating costs for catalytic 

de.composition systems vary widely because of differences in 

design philosophy and choices of heat and power recovery among different 

construction firms. Also, reported catalyst life varies from several 

41 
months to several years. Cost estimates for a moder.n plant with a capacity 

of 300 tons per day show that full control adds 1 percent to the cost 

of the most typical product, ammonium nitrate, and represents 4 to 8 

percent of the total capital investment for the facility. 

REFERENCES 

1. Private communication from Joseph Pavey, Product Specialist, 

Matthey Bishop, Inc., Philadelphia, Pa. July 8, 1971. 

2. Rule No. 59, Rules and Regulations. Air Pollution Control District, 

County of Ventura, California. 

3. Gerstle, R. W. and R. F. Peterson, Atmospheric Emissions from 

Nitric Acid Manufacturing Processes. U.S. DHEW, PHS. Division of 

Air Pollution. Cincinnati, Ohio. PHS Publication Number 999-AP-27. 

1966. 89p. 

42 
TECHNICAL REPORT NO. 5 -

SULFURIC ACID PLANTS 

SUMMARY OF PROPOSED STANDARDS 

Standards 6f performance are being proposed for new contact-process sulfuric 

acid and oleum facilities that burn elemental sulfur, alkylation acid, 

hydrogen sulfide, organic sulfides, mercaptans, or acid sludge. They 

do not apply to metallurgical plants that use acid plants as S02 control 

systems, or to chamber process plants or acid concentrators. 

The proposed standards establish limitations on sulfur dioxide and acid 

fllist emissions, and attendant visible emissions. 

The emission limitations being proposed are summarized as follows: 

Sulfur Dioxide 

No more than 4.0 pounds of sulfur dioxide (S02) per ton of acid 

(100 percent H2so4) produced or 2.0 kilograms S02 per metric ton. 

Acid Mist 

l. No more than 0.15 pound of acid mist (measured as H2so4) per ton 

of acid (100 percent H2

S04) produced or 0.075 kilogram acid mist 

per metric ton. 

2. No visible air pollutants shall be released to the atmosphere. 

43 
The standard allows about 0.3 percent of the feedstock sulfur to 

be released to the atmosphere as so2. For a typical plant, the sulfur 

dioxide standard is equivalent to an exit-gas concentration of 280 ppm. 

Where rich so2 streams (greater than 8.0 percent) are processed, the 

equivalent concentration will be greater than 280 ppm. Conversely, 

where weak so2 streams are handled, permissible concentrations will be 

lower and more restrictive. The range 180 to 350 ppm will cover emissions 

from most contact acid plants. 

The acid mist standard of 0.15 pound per ton of acid is equivalent to 

a concentration of 0.8 mg of sulfuric acid per standard cubic foot 

of.effluent for a typical sulfur-burning system. Volumetric equivalent 

concentrations in milligrams per standard-cubic foot(mg/scf) will vary 

from plant to plan·t because they are dependent on the inlet sulfur dioxide 

concentration. 

EMISSIONS FROM SULFURIC ACID PLANTS 

Almost all existing domestic contact-process sulfuric acid plants are 

of the single-absorption design and have no sulfur dioxide emission 

controls. Emissions from these plants range from 1500 to 6000 ppm so2 

by volume, or 21.5 to 85 pounds of so2 per ton of acid produced. Several 

state and local agencies limit so2 emissions to 500 ppm from new sulfuric 

acid plants, but few such facilities have been put into operation. 

Many sulfuric acid plants utilize some type of acid mist control device, 

but a significant number have no controls whatever. Uncontrolled acid \ 

mist emissions vary between 2 and 50 milligrams per standard cubic 

foot (mg/scf), or 0.4 to 9 pounds of H2

so4 per ton of acid produced. 
The lower figure represents emissions from a plant burning high-purity 

sulfur. State and local regulatory agencies have only recently made 

limits on acid mist emissions more stringent; some agencies, for example, 

have adopted limits of 1 and 2 mg/scf, respectively, for new and existing 

plants. 

JUSTIFICATION OF PROPOSED STANDARDS 

The proposed performance standard for S02 is based on inspections and 

stack tests of existing facilities; consultations with operators, 

designers, and state and local control officials; and review of the 

literature. Appreciable information concerning existing single-absorption 

plants was derived from a cooperati.ve study initiated in 1962 by the 

Manufacturing Chemists' Association, Inc., and one of EPA's predecessor 

organizations, the National Air Pollution Control Administration. Results 

of the study were published in a Public Health Service document, Atmospheric 

Emissions from Sulfuric Acid Manufacturing Processes. 1 

Much reliance necessarily had to be placed on the two demonstrated so2 

removal processes and on the single domestic applicati~n of each process 

to full-scale acid production facilities. Tests of the two plants for 

both acid mist and so2 emissions were conducted in 1971 by EPA personnel, 

using test methods presented in the regulations. 

Sulfur Dioxide 

The two plants tested and evaluated by EPA engineers were: (l) a plant 

of typical dual-absorption design and (2) a conventional single-absorption 

spent-acid-burning plant that uses a sodi urn sulfi te-bi sulfite scrubbing 

·process to recover so 2 from tail gas. The dual-absorption plant keeps 

45 
so2 emissions low by converting more of the feedstock sulfur to sulfuric 

acid. Other processes in use can control so2 to the levels set by the 

proposed standards; however, they are considered suitable for special 

situations only since they produce either a weak acid or a by-product 

that has limited marketability. 

Over 20 dual-absorption plants that have been operating successfully in Europe for several years use both elemental sulfur arid roaster 

gas as feed. The literature reveals that three of these plants produce 

maximum emissions ranging from 1.2 to 3.1 pounds of so2 per ton of acid 

produced, or 91 to 260 ppm so2 by volume. 

The first U. S. dual-absorption plant was put into operation in 1970 

and has been in continuous operation since then. Stack tests conducted 

by both EPA and company personnel show that so2 emissions normally do 

not exceed the limits of the perfonnance standards. During EPA tests, 

the facility was being operated at only 52 percent of rated production 

and so2 emissions were correspondingly lower than normal, ranging from 

1.5 to 1.9 pounds per ton of acid produced. These values were corroborated 

by company tests. Testing by the operator showed full-load S02 emissions 

to be consistently less than 4.0 pounds of so2 per ton of acid, with 

emissions below 3.0 pounds per ton much of the time. 

It has been demonstrated that sulfur dioxide can be removed from tail 

gases of single-stage acid plants by means of a sodium sulfite-bisulfite 

scrubbing process. In this system, so2 is thermally recovered from the 

scrubbing solution and fed back to the acid-manufacturing process. The 

only full-scale sulfite-bisulfite system was installed on an existing 

spent-acid plant in 1970. Since January of 1971, it has been in continuous 

~6 
operation. Tests of this plant by EPA personnel have shown emissions 

of 2.6 to 2.9 pounds of so2 per ton of acid produced. The tests represent 

some 18 hours of testing over a 3-day period. Similar tests conducted 

by company personnel indicate that the plant is capable of sustained 

operation at this level of so2 collection. 

Sulfite-bisulfite scrubbing processes produce waste liquor that contains 

sodium sulfate and sodium thiosulfate. Methods for disposing of these 

products will have to be considered by plant operators. The process 

designers are investigating several means of handling these wastes. 

Continuous stack monitoring at the plants tested indicates that at full 

load the plant can be consistently operated so that emissions are kept 

within the limits of the performance standard. Emissions exceed these 

values only during abnormal operation, and on these occasions the values 

are seldom more than 6.5 pounds of so2 per ton of acid produced, or about 

500 ppm. As openators obtain more experience with these systems, 

abnormal operating conditions are expected to occur less frequently. 

Acid Mist 

Review of the literature and investigations by EPA engineers showed that 

many existing· plants have already installed high-effi.ci.ency a·c.i'd-m.i.st 

eliminators, i.ncluding both fiber demisters and w.ire and tube electrostatic precipitators·. Fiber demisters. are more commonly employed. in· 

the industry. 

47 
The standard for new sources is based principally on stack tests conducted at the two plants that use sulfur dioxide control systems. EPA 

tests of the dual-absorption plant and the plant using the sulfite 

scrubber system show that acid-mist emissions can be held below the 

standard. The lowest levels, 0.02 pound per ton of acid produced, 

were recorded at the dual-absorption plant during periods when the 

plant was operating at about one-half load. At other times, the acid 

mist emissions from the two plants ranged from 0.04 to 0.15 pound per 

ton of acid produced. 

It must be emphasized that the acid mist standard is based on results 

obtained with the EPA method published in the regulations. Measurements 

with other test methods may give greater or lesser values, depending on 

whether the method measures sulfur trioxide (50 3) and acid vapor. (The 

latter two materials are sometimes considered under the collective 

term "acid mist.") Acid vapor and 503 are converted to acid mist on 

cooling and/or moisture absorption. 

Inasmuch as new plants will be required to install either the dualabsorption process or a tail-gas scrubbing system, it would.appear 

that emissions from the plants tested are representative of emissions 

from new plants. It is uncertain whether the dual absorption or the 

sulfite scrubbing process inherently reduces acid mist levels below those 

that would normally be encountered from a single-absorption plant. In 

any case, the literature indicates that both high-efficiency fiber 

demisters and electrostatic precipitators can reduce acid mist emissions 

2 to 0.10 pound per ton of acid produced. The most severe conditions 

possibly are encountered at spent-acid plants that process oleum (fuming 

413 
sulfuric acid). The best-controlled plants of this type produce no 

visible emissions. 

ECONOMIC IMPACT OF PROPOSED STANDARDS 

It is estimated that over the next few years two new sulfuric acid plants 

will be constructed annually in the United Stat~s. 

Sulfur dioxide control systems represent a significantly greater capital 

investment than acid mist collectors. Nevertheless, so 2 control systems 

provide a dividend to the operator in the form of increased acid yields. 

Elevated sulfur costs provided part of the incentive for the development of 

the dual-absorption process. The economics of high-yield processes such 

as dual absorption and sulfite scrubbing will continue to be dependent on 

the price of sulfur, with higher prices favoring greater S02 control. 

The standard of performance for sulfur dioxide is insensitive to cost;._· 

benefit analysis because no other control systems are available. The 

alternative would be a single-stage plant with no so2 control. 

The costs of control vary with location. Nevertheless, new plants would 

be expected to use the dual-absorption process, whereas modified existing 

plants would probably use an S02-scrubbing systQm, such as the sulfitebisulfite process. A dual-absorption plant with a 700- to 750-ton-perday capacity may cost 22 percent more than an uncontrolled single-absorption 

plant; however, the operating costs are essentially the same. Full control 

adds 3 to 5 percent to the cost of sulfuric acid, not including return on 

in\lestment. 

A new single-absorption plant, of the same capacity, with a sodium 

sulfite-bisulfite scrubbing process attached may cost 35 percent 

tl9 
more than an uncontrolled plant. The so 2

-control cost is about 

5.5 percent of the sulfuric acid list price, without return on 

investment. 

Acid mist control equipment is relatively less costly, representing 

from 1 to 2 percent of the capital investment of a 700- to 750-tonper-day plant. The additional operating costs, including amortization, 

represent 0.1 to 0.7 percent of the current sulfuric acid list price, 

depending on the type of control equipment used. Again, return on 

investment is not included. 

REFERENCES 

1. Atmospheric Emissions from Sulfuric Acid Manufacturing Processes. 

Cooperative Study Project:Manufacturing Chemists• Association, Inc., 

and Public Health Service. U.S. DHEW, PHS. Division of Air Pollution. 

Cincinnati, Ohio. PHS Publication No. 999-AP-13. 1965. 127 p. 

2. Chemica Construction Corporation. Engineering Analysis of Emissions 

Control Technology for Sulfuric Acid Manufacturing Processes. Final 

Report under Contract No. CPA 22-69-81, Public Health Service. U.S. 

DHEW, PHS. National Air Pollution Control Administration. Durham, 

N.C. Publication No. PB-190-393. March 1970. 

3. Economic evaluation is based on process and equipment costs obtained 

from manufacturers of various sulfur dioxide and acid mist control 

equipment, from sulfuric acid plant operators, and from Reference 2. 

50