.

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## BACKGROUND INFORMATION FOR PROPOSED NEW-SOUR.CE PERFORMANCE STANDARDS:

e • • • • 

## Steam Generators lnci'nerators·· Portiand 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 ofAir Programs Research Triangle Park, North Carolina August 1971Office ofAir Programs Technical Report No. APTD-0711

i i

## CONTENTS
INTRODUCTION TECHNICAL REPORT NO. 1 - STEAM GENERATORS Summary of Proposed Standards ParticulateMatter Sulfur Dioxide Nitrogen Oxides Emissions from Steam Generators Justification of Proposed**Standard~** ParticulateMatter Sulfur Dioxide Nitrogen Oxides Economic Impact of Proposed Standards ParticulateMatter
.. SulfurDioxide 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
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i i i Page 1 3 3 3 4 4 5 8 9 10 13 14 15 16 16 17 19 19 20



# .. 21 23 25 27 27ParticulateMatter from Kilns
..... ParticulateMatter from Clinker Coolers ParticulateMatter from Other Equipment
. Emissions from Portland Cement Plants
. Justification ofProposed Standards
. ParticulateMatter from Kilns and Clinker Coolers ParticulateMatter from Other Equipment Economic Impact of Proposed Standards
. References
........ . TECHNICAL REPORT NO. 4 - NITRIC ACID PLANTS Summary of Proposed Standards
. . Emissions from NitricAcid Plants
. Justification of Proposed Standards Economic Impact of Proposed Standards References
. . . . . . . . TECHNICAL REPORT NO. 5 - SULFURIC ACID PLANTS Summary of Proposed Standards SulfurDioxide Acid Mist
... Emissions from Sulfuric Acid Plants Justification of Proposed Standards SulfurDioxide. Acid Mist
... Economic Impact of Proposed Standards References.

iv 27 27 28 28 30 30 31 32



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# . 34 37 37 38 39 41 42 43 43 43 43 44 45 45 47 49 50

## INTRODUCTION

This document provides background information on the derivation of the proposed new-source performance standards and theireconomic impact on the construction and ooeration ofnew steam generators, municipal incinerators, sulfuric and nitric acid manufacturing facilities, and portland cement plants. The proposed standards, published in the Federal RegisterunderTitle42 CFR Part 466, are being distributed ·concurrentlywith this document. The information presented herein was

prepared for the purpose offacilitating review and comment prior to promulgation ofthe standards.
The performance standards were developed after consultationwith 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 ofcomments provided by these committees and by other individuals having knowledge regarding the control ofpollution from the specific source categories.
The National Air Pollution Control Techniques Advisory Committee is made up of 16 persons who are knowledgeable concerning airquality, air pollution sources, and technology for the control of air pollutants. The membership includes state and local control officials, industrial representatives, universityprofessors, and engineering consultants.Members are appointed by the EPA Administrator pursuant to Section 117 (d), (e), and (f) ofthe 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 ismade up of representatives of 19 Federal agencies.
The promulgation ofstandards ofperformance for new stationary sources under Section 111 ofthe Clean Air Act does not prevent state or local jurisdictions from adopting more stringentemission 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 otherpolitical 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,
or0.36 gram per million calories. 2. Visible emissions shall not be darker in shade than that designated
as No. 1on the Ringelmann Scale or 20 percent equivalent opacity, except for 2minutes in any one hour when emissions may be as great as No. 2on the Ringelmann Scale or 40 percent equivalent opacity.
3Sulfur Dioxide l. No more than 0.8 pound of sulfur dioxide permillion Btu heat input, or l.4 grams permillion calories, when liquid fossil fuel is fired. 2. No more than l.2 pounds of sulfur dioxide permillion 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 ofnitrogen oxides (measured as N02) 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 astack concentration level of0.12 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; ifparticulates are ator below 0.20 pound per million Btu, visible emissions normally will be less than 20 percent opacity.The proposed S02limits 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 of0.7 percent sulfuror less, orfor fuel oil of0.8 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-firedoperations were completely uncontrolled, particulate emissions would range from 6to 10 pounds permillion Btu. At most existing installations, emissions range from 1to 4pounds per million Btu. Particulates from oil-fired steam generators are seldom controlled except for mechanical collectors, which are used chieflyduring periods of soot blowing. Particulateemissions from uncontrolled oil-fired steam generators normally range from 0.04 to 0.06 pound per million Btu, with most ofthe particulates traceable to inorganic ash in the oil. Unless the ash content of the oil is excessive (greaterthan 0.4 percent by weight), or unless there is poor combustion, particulateemissions are well below the limits of the standard. Most state and local regulations limitparticulateemissions from coalfired steam generators to a level between 0.10 and 0.80 pound permillion
5Btu heat input. Afew**jurisdiction~** have more stringentrestrictions 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 of0.20 pound per million Btu heat input
are based on American Society ofMechanical Engineers (ASME) testing procedures that are different from the specified EPA testmethod. Although no definite correlation between these methods has been established, itappears that the proposed new-source standard is consistentwith a level of about 0.07 pound per million Btu if the ASME test procedure is used as the reference testmethod. Despite the numerical difference, both standards require about the same degree of control.
With existing fuel sulfur levels, uncontrolled S02 emissions range from 1to 7pounds 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

## so2emissions from combustion sources by restricting sulfur in fuels. Stack-gas desulfurization usually can be utilized rtt the option ofthe operator. Fuel sulfur limits of 0.50 to l.0 percent (0.5 to l.4 pounds permillion Btu) have been established in a number of areas of the country.
Most of the steam generators in the United Stateswere 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
6pounds 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 thatwould allow the use of combination control systems to collect both particulates and sulfur dioxide. Itdoes not appear that the particulate/S02systems 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.
7The fact thatmost low-sulfur fuel oil or crude oil will have to be imported from Alaska or from foreign countries. Substantial quantities ofdesulfurized fuel oil will be available from Caribbean facilities, several ofwhich 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 ofthe coal.
The fact that stack-gas desulfurization processes have only recently been developed to the point atwhich they can be applied to steam generators. The first new steam generators to be affected by the standards will be put intooperation in 1975 and 1976. In many cases owners and operators can delay decisions on a1r pollution control equipment for ayear or longer after the steam generator has been designed. At that time there should be a greater number ofoptions for sulfurdioxide control schemes from which to choose.
JUSTIFICATION OF PROPOSED 1STANDARDS The proposed performance standards are.based on inspections and tests of prototype and full-scale control systems, on consultationswith state and local officials and operators and designers of steam generators and control systems, on EPA surveys ofavailable combustion fuels, and on review ofthe literature. Essentially all ofthe technology applicable to the subject was developed in the United States.The adequately demonstrated techniques include the use ofelectrostatic 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 ofthe 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 thatwere 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

## so2removal 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 consistentwith the standard.
9To 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 ofthe data available in the literature are based on the American Society ofMechanica1Engineers (ASME) testmethod, which generally reflects lower particulate loadings than the EPAmethod. Reported values with the ASME method range below 0.05 pound permillion Btu for high-efficiencyelectrostatic precipitators. Visible emissions were recorded at the seven coal-fired installations where particulateswere measured. At the two plants thatmet the proposed standard, as well as at the two steam generators thatbarelyexceeded the standard, visible emissions were less than 20 percent opacity. No black smoke was observed atany ofthe tested installations.

Sulfur Dioxide The standards for sulfurdioxide are based on limited demonstrations ofstack-gas desulfurization processes and on the availability oflowsulfur 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 ofcontinuous operation at smaller installations. Alime-slurry scrubbing system, demonstrated for 6months on two coalfired units of 125 and 140 mW capacity, approached the 

### so2emission limit 10ofl.2pounds per million Btu. This operation represents 73 percent removal of

## so2from fuel gases in instances where the bituminous coal contains 3.0 percent sulfurby weight. One ofthe units was selected for the EPA test program, resulting in a verification ofthe

## so2removal

**pt~rformance** reported by the contra1systern 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. Aprototype unit, however, employing a dual-bed design, has achieved emission levels as low as 1.0 pound permillion Btu heat input for an extended period oftime.2 This system is also apolicahle to steam generators burning fuel oil. The demonstrated removal efficiency (76 percent), applied to atypical fuel oil of 2.5 percent sulfurcontent, results in an emission level of0.7 pound permillion Btu heat input, which is below the standard ofperformance.

**Lim~-scrubbing** systems are essentially throwaway processes that produce significantquantities of solid waste. For a 3.0-percent-sulfur coal, the additional wastes are roughly equal to the ash generated from burning coal. Some otherprocesses have been utilized onpilotor 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 3years. 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 ofoperation 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 plantwith 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. Afull-scale**ma~nesium** 

### t ...>')(I!!Jet' oxide scrubbing system is being installed to serve a

### bd**,!~Btu-per** hour 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 atmany 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
12far 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 ofmeeting 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
13publications at levels below the standard ofperformance for liquid fuels.6•7 Combined methods show promise ofmuch 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 ofnitrogen oxides thatwere well below the required level of0.7 pound permillion Btu. Published data from numerous sources, and othertest results from steam-generatormanufacturers, 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 firedand wall"fired steam generators when combustion modifications**~re** employed. Emission levels are anticipated to be considerably lower than the standard aftercombined 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 ofthe total capacity ofnew units greaterthan 250 million Btu heat per hour inputwill be utilizedby the electrical utilityindustry. Since construction of steam generators requires from 3to 5years, 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 ofa steam-electric generation unit. Since units burning gaseous fuels need only control NO , the capital investment will amount to only 5percent 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 4percent for gaseous fuels. More stringent requirements to meet ambient airquality standards as specified by state implementation plans (Section 110 of the Clean Air Act) will force control costs much higher in some areas.
Particuiate 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 amarginal additional cost resulting from the particulate standard. The total costs, however, reflect an allotment for an increase of 6percent in the total capital investment and 4percent 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 efficientprecipitators and scrubbers
15would require thatthe standard be relaxed by afactor of 2with a savings of up to 3percent of the total plant initial investment. Sulfur Dioxide Control costs for

## so2are by far the highest of the three pollutants, with increases of about 10 percent in capital investment and 7to 30 percent in operating costs. Sulfur dioxide control is not normally practiced by the steam-generation industry and will result in adirect additional cost in most areas. The reimbursements for salable by-products, such as elemental sulfurand sulfuric acid, were not included as credits in the cost estimates because of themarket variabilities involved. In addition, the cost for disposal of spent reagents incurred by some processes was not considered in any depth.
The standards ofperformance are insensitive to cost/benefit analysis when· stack-gas cleaning is employed in that it is the only control system available. Since the availabilityoflow-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 cleaningmay force the opening of new mines tomeet demand. Nitrogen O)(ides Nitrogen oxides combustion-modification economics are similarto those for electrostatic precipitators, with capital investment increases approaching 7percent as amaximum, and elevation in operating costs reaching 4percent. The capital investment should decline to 0percent, however, as combustionmodification becomes common practice and not a special modification. Afew coal-fired steam generator designs inherently rroduce high levels ofNOx, and it 16is unlikely that some ofthese can bemodified tomeet the standards. Three of the four major steam-generatormanufacturers 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 percentof the coal-fired steam-generatormarket. 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 ofAir Programs (internal briefing document), Division of Control Systems, Environmental ProtectionAgency, 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 thatwiil limitparticulate 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 adry filter as well as \'let impingement collectors. The standards ofperformance would

**~pply** only to thdse incinerators used to burn predominantly municipal solidwastes, e.g., household and commercial paper, cardboard,

**g~rbage,** and yardwastes. The standards will not apply to incinerators used exclusively to burn sewage sludge, pathological wastes, sawdust, orother specialized trade wastes. The proposed standardwould limitparticulateemissions to the atmosphere
as fo11mJs: No more than 0.10 grain ofparticulates per

**stand~rd** cubic foot (scf) of dry flue gases, corrected to 12 percent carbon dioxide (C02). For burning of typical solidwastes in the United States, the limitof0.10 grain per scf, corrected to 12 percent C02, corresoonds to the production of 1.9 pounds ofparticulates per ton of solidwastes charged to the 19incinerator, and about 0.17 pound ofparticulates per 1000 rounds of flue gas, corrected to 50 rercent excess air.

EMISSIONS FROM INCINERATORS An uncontrolled incineratorwill emit considerably more particulates than the standard allows. Available data indicate that, on the average, uncontrolled furnace gases contain about 1grain ofparticulates per scf dry gas at 12 percent

## co2.1,2 For average domestic solidwaste, this corresponds to about 19 pounds ofparticulates per ton ofwastes burned
.. In most cases, these datawere obtained using sampling methods different from the EPAmethod that is to be used to determine compliance. Gases from existing furnaces, therefore, may contain somewhatmore than 1 grain ofparticulatematter per scf. The range of 15 to 30 pounds of particulates per ton ofwaste charged probably covers most existing incinerators ofconventional 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 testmethods that differfrom the EPA technique. Although no definite correlation between these methods has been established, it appears that the proposed standard is not inconsistentwith the most stringent state-stJndards in existence, which are based on the test procedure of the American Society ofMechanical Engineers. Despite the numerical difference, both standards will require approximately the same degree of particulatecontrol. 20JUSTIFICATION. OF PROPOSED STANDARDS The proposed performance standards are based on astudy ofincinerators in the United States and Europe. -Information was obtained by inspections and stack tests ofoperating plants and by consultationwith designers, plant operators, and state and local control officials. The Systems Study ofAir Po11ution from Municipa1 Incin.eration,1performed under contractby Arthur D. Little, Inc., provided acomprehensive review ofAmerican operations and incineratortechnology. The study showed that almost all existingmunicipal incinerators release excessive amounts ofparticulates and that, until recently, none were equipped with high-efficiency particulate collectors.
Investigations by EPA engineers show thatelectrostaticprecipitators, fabric filters, and high-eriergy scrubbers are being utilized to control· particulates from municipal incinerators. Tests using the EPAmethod show that particulateemissions from precipitators are within the limits ofthe proposed standard. European tests and pilot studies in this country also indicate that fabric filters will provide sufficientparticulate control to meet the standard. On.one recent installation of a venturi scruhber, the designer guaranteed particulateemission levels consistentwith the prorosed standard.
21Of 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 controlledwith ahigh-energy venturi scrubber. Two of the domestic precipitators were testedby EPA and EPA contractors. Particulateemissions ranged from 0.07 to 0.09 grain per scfdry gas, corrected to 12 percent

## co2. These values were the average ofthree 2-hour sampling runs ateach plant. One ofthe values was confirmed in an independent test in which the EPA sampling method was used. At one ofthe 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 efficiencyofbetterthan 99.0 percent in removing particulates. Two European plants, one in Germany (with an efficiencyof99 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 scfofdry gas at 12 percent C02. The German plantwas tested by European methods both before and during the EPA tests. Results of all tests
- by bothEuropean and EPA methods

- are in approximate agreement. The U.S. plants tested are ofboth refractory and water-wall design, and capacities range from 300 to 400 tons ofmunicipal refuse per day. The European incinerators were ofwater-wall design, with capacities ranging from 220 to 400 tons ofmunicipal 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
22small Swiss unit (36 tons per day) with afabric filterwas testedwith European sampling procedures; measured values averaged 0.04 grain per scf, corrected to 12 percent CO
.3 Lower emissions ofparticulates 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 notyet available for the one high-energy scrubber in use. The venturi scrubber is operated with a 12-inch (water column) pressure drop, and itserves a240-ton-per-day incinerator. The designer has guaranteed an emission level consistentwith the performance standard. ECONOMIC IMPACT OF PROPOSED SlANDARDS 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 availabilityof alternative solidwaste 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 costmore 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 23based on extensive review ofmanufacturers' quotations, estimated by Little to have an accuracy ofplus 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 ofperformance is sensitive to cost/benefit analysis based on the use ofelectrostatic precipitators, scrubbers, orbaghouse 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 ofamechanical collectorwould require that the standard be relaxed by a factor of4. 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 $150,000 for high-efficiency control equipment. Installed·costs of control equipment are therefore about 15 percent of the entireplant costs. For plants with acapacity of 300 tons per day, costs decrease to 13 percent of the incinerator cost.
For a**100-~n-per-day** water-wall furnace, incinerator costs are about .# 1.151.10 '**$M,53~90~** installed, including about $105,000 for the cost ofhigh-efficiency control equipment. Control equipment costs are therefore about 9percent of installed costs for the 100-ton-per-day plant. This decreases to about 5rercent for a 300-ton-oer-day plant.
211.The cost ofoperating the control equipment at the refractory furnace plant ranges from $29,000 (100 tons per day) to $65,000 (300 tons per day) peryear. For the water-wall plant, these costs are $13,000 (100 tons per day) and $23,000 (300 tons per day) peryear. Refuse generation rates as determined by the Office ofSolid 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 peryear, decreasing as furnace capacity increases.

REFERENCES
l. Systems Study ofAir 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 ofAir PollutantEmission 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 ofAmerican 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 ofperformance 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 thatdesiqnated
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
27to 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 adry**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 5percent 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 ifmass emissions are ator below the respective limits, visible emissions will be at orbelow 10 percent opacity from the kiln and no emissions will be visible from the clinkercooler. Observations of the other process equipment

- mills, conveyors, etc.
- have shown that no visible emissions occur ifcommon dust collection equipment is installed and properly maintained.
EMISSIONS FROM PORTLAND CEMENT PLANTS Poorly controlled kilns can release as much as 45 pounds ofparticulates to the atmosphere per ton of raw material processed, and poorly controlled 2.']clinkercoolers can release as much as 30 pounds ofparticulates per toh

. ,1,2,3 ofraw mater1a
. Such installations are likely to be equipped only with centrifugal dust collectors. The proposed standards would require owners and**ope~ators** ofnew facilities to reduce the level ofparticulate emissions to 99.3 percent below that of avery poorly controlled kiln and 99.7 percent below that of avery poorly controlled clinkercooler.

At many modern cement plants eitherelectrostatic precipitators or baghouses are used to collectdust 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, transferpoints, storage silos, etc. Many of the dust collectors serve to recover product from exhaust gas streams and to increase productyields. Their function as air pollution control devices may, therefore, be secondary.

Many state and local regulations, unlike the proposed standards, allow particulateemissions to vary with the rate of input ofraw materials. For atypical 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 ofwhich are higher than the proposed standards. Afew 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.
29JUSTIFICATION FOR PROPOSED STANDARDS 

### The proposed performance standards are based on inspections and stack tests ofexistingfacilities; consultationwith plantoperators and designers, control equipmentmanufacturers, and state and local control officials; and review ofthe literature. Aprincipal literature source ·was agovernment publication, resulting from acooperative study

conducted with representatives ofcompanies manufacturing portland cement, entitledAtmospheric Emissions from the Manufacture of Portland Cement.1 Preliminary investigations revealed the locations ofthe 12 reportedly**best~controlled** 

### plants in the United States. No information obtained indicated thatforeign 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; judgmentwas also made as to the feasibility of conducting stack tests. Five locations were unsatisfactorybecause control equipmentwas inadequate or the physical layout ofthe equipment made itimpossible to conduct tests (e.g., apressure baghouse thatdoes not have astack). Stack tests were conducted at seven locations and covered four kilns, three clinkercoolers, and four**raw~material** 

### and finished-product mills.
Particulate Matter from Kilns and Clinker Coolers 

### Four kilns, as stated,were tested by EPA; corroborative testdata were obtained from alocal airpollution control agency on one of**the~EPA** 

### tested kilns. Results ofonly three tests were available at the time the standards were proposed. Neither of the two wet-process kilns controlled
30with electrostatic precipitatorswas able to meet the proposed standards. Atestof adry-process kiln controlledwith abaghouse, however, showed particulateemissions of0.20 pound per ton of feed, which is below the proposed standard. Inspections were made ofthree**additio~al** kilns controlledwith baghouses. No visibleemissions were produced from the latterthree kilns, although one**wet-proce~s** kiln showed amoisturecondensation plume during cold weather. These kilns were not tested because of the physical layoutof the equipment. Three clinkercoolers were tested by EPA. The coolerwith an electrostaticprecipitatorand one of the two units with baghouses were shown to meet the proposed standard. No visible emissions were observed from two additional clinkercoolers with baghouses, although they were not tested due to the physical layout ofthe equipment
.. Investigations confirmed that fabric-filter collectors can be applied to both kilns and clinkercoolers in conventional**wet~** and dry-process portland cement production facilities to reduce particulateemissions to the limits of the proposed standards. It is possible thatelectrostatic 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 existingplants, since tests of the two kilns with electrostaticprecipitators showed that neitherwas able to meet the proposed standards. No otherparticulate abatement schemes have been demonstrated to be capable ofachieving the standards, although investigations ofhigh-energy scrubbing are underway.
Particulate Matter from Other Equipment No emission standards otherthan visible emission limits have been proposed
31

### for otherequipment in cement plants, such as raw-material mill systems' finished-productmill 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 ofbaghouses, although precipitators sometimes are used on finish mills. These devices prevent loss ofmaterial from the process and reduce airpollution. In most instances, the economics ofmaterial recovery are sufficientto justify the abatement devices without regard to airpollution control regulations. Inspections by EPA engineers show that no visible emissions occur from these devices when they are properlymaintained: Where visible emissions are encountered, they are likely to be the resultofbag fatlure.4
ECONOMIC IMPACT OIF IPROIPOSIEIO STANDARDS 

### Itisestimated thatthree new Portland cement kilns and associated equipment will be constructed in the U. S. each year and thatthree existing systems will be modified to the extent that they will come 5 

### under the proposed standards. Many stateand local agencies presently have regulations for cement plants thatrequire the same types ofdust-control equipmentmandated by the proposed standards. These standards will not result, then, in an appreciable increase in the costofanew cement plant. The only significantincrease in costwould be to acompany thatwould otherwise have constructed apoorly controlled plant in an area not covered_by adequate stateor local regulations. In any case, the installed investment and operating costs ofbaghouse collectors and electrostaticprecipitators cannot be attributedentirely to airpollution control because many ofthe devices are used for product recovery and 32are economicallyjustifiableon thatbasis. Thus, investment costs cannot be computed for air pollution control alone.

The standard ofperformance for the kiln is sensitive to cost/benefit analysis. The standard is based on a baghouse collector; eiectrostatic precipitators are alternativecontrol devices. The use ofelectrostatic precipitators ofefficiencies consistentwith existing installations would require that the standard be relaxed by afactor of 3with a saving ofonly about 1percent of total plant investment. More efficientprecipitators could be installed, but the costwould be about 1.1 times that ofbaghouses. The trend in the cement industry is toward the use ofbaghouse collectors, and this trend should be encouraged.

For anew wet-process plantwith a capacity of2.5 million barrels peryear (90 tons offeed per hour to the kiln), the total investment for all installed air pollution control equipment will represent approximately 12 percent ofthe investment for the total facility. The cost ofcontrol equipment for the clinkercoolerwill be approximately 10 percent ofthe cost of all air pollution equipment. An electrostatic precipitatoror baghouse for the kiln represents approximately 60 percent ofthe cost of all airpollution equipment. The remaining 30 percent of the costs will cover dust control for the finished-product mill grinding system, conveyors, transferpoints, storage silos, etc. Annual operating costs for the control equipment will be approximately 7percent ofthe total plant operating costs if a baghouse is used for the kiln, and 5percent ifan electrostatic

. 't t . d 5,6 prec1p1 a or 1s use . 33

### For anew plantof2.5 million barrels peryear,**~sing** 

### the dry process, the total installed investment costofall airpollution control equipment will be slightlyhigher than 13 percent ofthe total facility investment because additional control equipmentwill 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 ofthe proposed standards on control-equipmentmanufacturers will be small. Because the majormanufacturers of control equipment offeracomplete line (electrostaticprecipitators, baghouses, and scrubbers), the possible reduction in sales ofelectrostatic precipitators will have littleeconomic 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 ofPortland 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 ofAir PollutantEmissions Factors. Preliminary Document. Environmental ProtectionAgency. Research**Trian~le** 

### Park, N. C. April 1971. 3. Guidelines for Control ofEmissions from**Cem~nt** 

### Plants. Internal Document. Environmental ProtectionAgency. 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 ofAir Pollution 34Control Upon the Cement Industry. Internal Document. Environmental ProtectionAgency. Raleigh, N. C. February 1971. 6. Personal communication from D. Stinner, Design Engineer, FullerCompany, Catasauqua, Pa. July 9, 1971.

35

## TECHNICAL REPORT NO. 4 - NITRIC ACID PLANTS
SUMMARY Of·PROPOSED STANDARDS Standards ofperformance 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 ofweak acid, or by the direct strongacid process. The standards ofperformance are being proposed for total oxides of nitrogen and for attendant visible emissions, which are a function of nitrogen dioxide concentration. The standards would limitemissions to the atmosphere as follows: 1. No more than 3.0pounds of nitrogen oxides (NOx) per ton of acid produced or 1;5 kilograms NOx permetric ton, averaged over a 2-hour period. Acid produced is expressed in tons ofequivalent 100-percent.strength nitric acid, 2. Visible airpollutants shall not be released to the atmosphere. For a typical weak-nitric acid production facility, the standard of 3.0 pounds per ton ofacid 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 ofacid produced. 37EMISSIONS FROM NITRIC ACID PLANTS Without control equipment, nitric acid production facilities will release about 43 pounds of NOx per ton of acid produced at aconcentration of about 3000 ppm NOx (by volume) in the exitgas stream. Approximately 50 percentof 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 specificallydesigned to include NOx abatement, which is accomplished by means ofdecomposition ofNOx 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-ca11ed 11decolorizers11 convert visible N02 to colorless NO with the concurrent generation ofappreciable 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 of250 ppm NOx that governs njtric acid plants as well as steam generators and other sources.2

Visible-emission regulations with equivalentopacity provisions also restrict nitric acid manufacturing operations in many areas.**Never~** theless, operators can meet these requirements through the use of 33decolorizerdevices, which have littleeffecton total NOx emissions.
JUSTIFICATION OF PROPOSED STANDARDS The proposed performance standards are based on inspections and stack tests ofexisting facilities; consultations with operators, designers, and state and local control officials; and review of the literature. In 1962, acooperative projectwas initiated by the Manufacturing Chemists' Association and the U.S. Public Health Service to study emissions from selected chemical manufacturing processes. Agoal of that programwas to publish relevant information in a form helpful to control agencies and to the chemical industry. The results of the studywere 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 levelswithin 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 ofthe absorption tower atconventional 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, N02is 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
39tail gases. Asurvey ofthe ten plants in the United States that are equipped with**the~e** systems indicated that five were consistentlyachieving low NOx emission levels. Testing and inspection confirmed that three ofthe plants could be operated well within the performance standard. The other two were found to exceed the standard during EPA tests; theiremissions were 4.8 and 8.4 pounds ofNOx per ton ofacid produced. Both were found to be operating with partiallydeactivated catalyst. Company tests using accepted.test procedures indicated thatone of the facilities had been achieving an average of2.0 pounds NOx per ton of acid afew months prior to the test. At each installation, testingwas conducted for about 6hours on each of 3consecutive 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 ofdesign. 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 thateven the two systems with partially spentcatalystwere serving as effective decolorizers. Although no separate N02analyses were performed, it appears thatmost of 40the N02was converted to colorless NO. Thus, any facilitymeeting the mass NOx limitwill produce no visi'ble emissions from the stack.


### ECONOMIC IMPACT OF PROPOSED,STANDARDS Based on projectionsmade by nitric acid plant builders and operators, itis estimated thatconstruction ofnew plants will average five facilities peryear. In considering costs for NOx control, the assumption was made thatany new nitric acid facilitywould be equipped with acatalyticdecomposition system for heat recovery and possible NOx abatement even ifNOx limits were not imposed. In the absence ofany r-egulation on NOx emissions, this unitwould be operated as adecolorizerand would produce the heat recovery needed to drive aprocess-aircompressor. Abatement ofNOx requires that all oxygen be burned from the tail-gas stream; this is not arequirement for heat recovery. Consequently, the fuel used for decolorization and partial abatement is less thatthat necessary formeeting the proposed standards. Furthermore, typical catalystswill become inactive for NOx abatement purposes long before they lose theirabilityto decolorize.**Th~** standard ofperformance represents full control and is 1nsensitive to cost/benefitanalysis. The alternative is essentiallyno control. The standard ofperformance does not represent a significant increase in the capital cost for a new plant, although operating costs will increase as the resultof increased fuel use and decreased catalyst life. Estimates ofboth capital investment and operating costs for catalytic de.composition systems vary widely because ofdifferences in design philosophy and choices ofheat and power recovery among different construction firms. Also, reported catalyst life varies from several
41

### months to several years. Cost estimates for amoder.n plantwith acapacity of300 tons per day show that full control adds 1percent to the cost of the most typical product, ammonium nitrate, and represents 4to 8 percent ofthe 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 ofVentura, California. 3. Gerstle, R. W. and R. F. Peterson, Atmospheric Emissions from NitricAcid 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 thatburn 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 sulfurdioxide (S02) per ton ofacid (100 percent H 2

## so4)produced or 2.0 kilograms S02per metric ton. Acid Mist l. No more than 0.15 pound of acid mist (measured as H 2

## so4) per ton of acid (100 percent H 2S04) 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 ofthe feedstock sulfurto be released to the atmosphere as 

## so2. For atypical plant, the sulfur dioxide standard is equivalent to an exit-gas concentration of280 ppm. Where rich

## so2streams (greater than 8.0percent) are processed, the equivalent concentrationwill be greater than 280 ppm. Conversely, where weak

## so2streams are handled, permissible concentrations will be lower andmore restrictive. The range 180 to 350 ppmwill cover emissions from most contact acid plants.
The acidmist standard of0.15 pound per ton ofacid is equivalent to aconcentration of0.8mg of sulfuric acid per standard cubic foot of.effluentfor atypical 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 inletsulfurdioxide 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

## so2per ton ofacid produced. Several stateand local agencies limit

## so2emissions to 500 ppm from new sulfuric acid plants, but few such facilities have been put into operation. Many sulfuric acid plants utilize some type ofacid mist control device, but asignificantnumber have no controlswhatever. Uncontrolled acid \ 

### mist emissions vary between 2and 50 milligrams per standard cubic foot (mg/scf), or 0.4 to 9pounds ofH 2



## so4per ton ofacid produced.The lower figure represents emissions from aplantburning high-purity sulfur. Stateand local regulatory agencies have only recentlymade limits on acid mist emissions more stringent; some agencies, for example, have adopted limits of 1and 2mg/scf, respectively, for new and existing plants.
JUSTIFICATION OF PROPOSED STANDARDS The proposed performance standard for S02is based on inspections and stack tests ofexisting facilities; consultations with operators, designers, and stateand local control officials; and review of the literature. Appreciable information concerning existing single-absorption plantswas derived from acooperati.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 aPublic Health Service document, Atmospheric Emissions from SulfuricAcid Manufacturing Processes.1

Much reliance necessarilyhad to be placed on the two demonstrated 

### so2 removal processes and on the singledomestic**applicati~n** of each process to full-scale acid production facilities. Tests of the two plants for both acid mist and 

### so2emissions were conducted in 1971 by EPA personnel, using testmethods 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) aconventional single-absorption spent-acid-burning plant thatusesa sodiurn sulfite-bisulfite scrubbing ·process to recover 

### so2from tail gas. The dual-absorption plant keeps
45

## so2emissions low by converting more of the feedstock sulfurto sulfuric acid. Other processes in use can control

## so2to the levels setby the proposed standards; however, they are considered suitablefor special situations only since they produce eitheraweak acid or aby-product thathas limitedmarketability.
Over 20 dual-absorption plants that have been operating successfully in Europe for several years use both elemental sulfurarid roaster gas as feed. The literaturereveals that three of these plantsproduce maximum emissions ranging from 1.2 to 3.1 pounds of

## so2per ton ofacid produced, or 91 to 260 ppm

## so2 by volume. The firstU. S. dual-absorption plantwas put into operation in 1970 and has been in continuous operation since then. Stack tests conducted by both EPA and company personnel show that

## so2emissions normally do not exceed the limits ofthe perfonnance standards. During EPA tests, the facility was being operated atonly 52 percent ofrated production and

## so2emissions were correspondingly lower than normal, ranging from 1.5 to 1.9pounds per ton ofacid produced. These values were corroborated by company tests. Testing by the operator showed full-load S02emissions to be consistently less than 4.0pounds of

## so2per ton ofacid, with emissions below 3.0 pounds per ton much ofthe time.
Ithas been demonstrated that sulfur dioxide can be removed from tail gases of single-stage acid plants by means of asodium sulfite-bisulfite scrubbing process. In this system,

## so2is thermally recovered from the scrubbing solution and fed back to the acid-manufacturing process. The only full-scale sulfite-bisulfite systemwas installedon an existing spent-acid plant in 1970. Since January of 1971, ithas been in continuous**~6**operation. Tests of this plantby EPA personnel have shown emissions of2.6 to 2.9 pounds of

## so2per ton ofacid 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 ofsustained operation at this level of

## so2 collection.

Sulfite-bisulfite scrubbing processes produce waste liquor that contains sodium sulfate and sodium thiosulfate. Methods for disposing ofthese products will have to be considered by plantoperators. The process designers are investigating several means ofhandling these wastes.

Continuous stackmonitoring at the plants tested indicates that at full load the plantcan be consistentlyoperated so that emissions are kept within the limits ofthe performance standard. Emissions exceed these values only during abnormal operation, and on these occasions the values
are seldommore than 6.5 pounds of

## so2per ton ofacid produced, or about 500 ppm. As openators obtain more experience with these systems, abnormal operating conditions are expectedto 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. 

### 47The standard for new sources isbased principally on stack tests conducted at the two plants that use sulfur dioxide control systems. EPA tests ofthe dual-absorption plantand 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 ofacid produced, were recorded atthe dual-absorptionplantduring periodswhen the plantwas 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.
Itmust be emphasized that the acidmist standard isbased on results obtained with the EPAmethod published in the regulations. Measurements with other testmethods may give greateror lesser values, depending on whether themethod measures sulfurtrioxide (503)and acid vapor. (The lattertwo materials are sometimes considered under the collective term "acidmist.") Acid vapor and 503are converted to acidmist on cooling and/ormoisture absorption.

Inasmuch as new plantswill be required to install either the dualabsorption process or atail-gas scrubbing system, itwould.appear that emissions from the plants tested are representativeofemissions from new plants. It is uncertainwhether the dual absorption or the sulfite scrubbing process inherently reduces acid mist levels below those thatwould normally be encountered from a single-absorption plant. In any case, the literature indicates thatboth high-efficiency fiber demisters and electrostatic precipitators can reduce acid mist emissions 2 to0.10 pound perton ofacid produced. Themost severe conditions possibly are encountered at spent-acid plants that process oleum (fuming 413sulfuric 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 asignificantly greater capital investment than acidmist collectors. Nevertheless, 

### so2control systems provide adividend to the operator in the form ofincreased acidyields. Elevated sulfurcosts provided part ofthe incentive for the development of the dual-absorption process. The economics ofhigh-yield processes such as dual absorption and sulfite scrubbing will continue to be dependent on the price ofsulfur,with higher prices favoring greaterS02 control. The standard ofperformance for sulfur dioxide is insensitive to cost;._· benefit analysis because no othercontrol systems are available. The alternativewould be a single-stage plantwith no

## so2control. 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. Adual-absorption plantwith a 700- to 750-ton-perday capacity may cost 22 percentmore than an uncontrolled single-absorption plant; however, the operating costs are essentially the same. Full control adds 3to 5percent to the cost of sulfuric acid, not including return on in\lestment.
Anew single-absorption plant, ofthe same capacity, with a sodium sulfite-bisulfite scrubbing process attached may cost 35 percent
tl9

### more than an uncontrolled plant. The

## so2 -control cost is about 5.5 percent ofthe sulfuricacid listprice,without return on investment.
Acid mist control equipment is relativelyless costly, representing from 1to 2percent ofthe capital investment ofa 700- to 750-tonper-day plant. The additional operating costs, including amortization, represent0.1 to 0.7 percent ofthe current sulfuric acid listprice, depending on the type ofcontrol equipment used. Again, return on investment is not included.


### REFERENCES
1. Atmospheric Emissions from SulfuricAcid Manufacturing Processes. Cooperative Study Project:Manufacturing Chemists• Association, Inc., and Public Health Service. U.S. DHEW, PHS. Division ofAirPollution. Cincinnati, Ohio. PHS Publication No. 999-AP-13. 1965. 127 p.
2. Chemica Construction Corporation. Engineering Analysis ofEmissions Control Technology for SulfuricAcid Manufacturing Processes. Final Report under ContractNo. 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 ofvarious sulfurdioxide and acid mist control equipment, from sulfuricacid plantoperators, and from Reference 2.

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