BACKGROUND INFORMATION
FOR
PROPOSED NEW-SOURCE
PERFORMANCE
STANDARDS:
0 • • • e
Steam Generators
Incinerators
Portland Cement Plants
Nitric Acid Plants
Su If uric Acid Plants
U. S. ENVIRONMENTAL PROTECTION AGENCY
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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
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Office of Air Programs Technical Report No. APTD-0711
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CONTENTS
Page
INTRODUCTION .1
TECHNICAL REPORT NO. 1 - STEAM GENERATORS 3
Summary of Proposed Standards 3
Particulate Matter 3
Sulfur Dioxide 4
Nitrogen Oxides 4
Emissions from Steam Generators 5
Justification of Proposed Standards 8
Particulate Matter 9
Sulfur Dioxide 10
Nitrogen Oxides 13
Economic Impact of Proposed Standards 14
Particulate Matter 15
Sulfur Dioxide 16
Nitrogen Oxides 16
References 17
TECHNICAL REPORT NO. 2 - INCINERATORS 19
Summary of Proposed Standards '19
Emissions from Incinerators 20
Justification of Proposed Standards .... 21
Economic Impact of Proposed Standards 23
References 25
TECHNICAL REPORT NO. 3 - PORTLAND CEMENT PLANTS '. . . . 27
Summary of Proposed Standards 27
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Particulate Matter from Kilns 27
Participate Matter from Clinker Coolers 27
Participate Matter from Other Equipment 28
Emissions from Portland Cement Plants 28
Justification of Proposed Standards 30
Particulate Matter from Kilns and Clinker Coolers 30
Particulate Matter from Other Equipment 31
Economic Impact of Proposed Standards 32
References 34
TECHNICAL REPORT NO. 4 - NITRIC ACID PLANTS 37
Summary of Proposed Standards ... 37
Emissions from Nitric Acid Plants 38
Justification of Proposed Standards 39
Economic Impact of Proposed Standards 41
References ^
TECHNICAL REPORT NO. 5 - SULFURIC ACID PLANTS 43
Summary of Proposed Standards 43
Sulfur Dioxide 43
Acid Mist 43
Emissions from Sulfuric Acid Plants 44
Justification of Proposed Standards 45
Sulfur Dioxide 45
Acid Mist 47
Economic Impact of Proposed Standards 49
References 50
IV
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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 operation 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 agencies.
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.
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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
Commi ttee.
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.
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TECHNICAL REPORT 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 (including visible emissions), sulfur dioxide, and
nitrogen 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.
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Sulfur Dioxide
1. No more than 0.8 pound of sulfur dioxide per million Btu heat
input, or 1.4 grams per million calories, when liquid fossil
fuel is fired.
2. No more than 1.2 pounds of sulfur dioxide per million Btu heat input,
or 2.1 grams per million calories, when.sol id fossil fuel is fired.
Nitrogen Oxides
1. No more than 0.20 pound of nitrogen 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.liquid 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.
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The proposed SCL 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.
EMISSIONS 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 in-
stallations, emissions range from 1 to 4 pounds per million Btu. Partic-
ulates 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 coal-
fired steam generators to a level between 0.10 and 0.80 pound per million
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Btu heat input. A few jurisdictions' 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 genera-
tors 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 S0? emissions from combustion sources by
restricting sulfur in fuels. Stack-gas desulfurization usually can
be utilized at the option of the operator. Fuel sulfur limits of
0.50 to 1.0 percent (0.5 to 1.4 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
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pounds per million Btu. Only a few states and local jurisdictions
restrict NO emissions. Limits range from 0.15 to 0.60 pound per
A
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 enforce-
ment. 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 techniques
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 would allow
the use of low-sulfur fuels as well as fuel cleaning, stack-nas
cleaning, and equipment modifications.
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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. Coal-
cleaning 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 air 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 PROPOSED STANDARDS
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.
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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 precinitators
only a trace of the emissions was visible.
Tests of the one :>crubber showed particulate emissions of 0.32 pound per
million Btu. The marble-bed scrubber, however, was designed principally
for S02 removal rather than high-efficiency particulate control. Infor-
mation obtained from various pilot-scale test programs indicates that
advanced scrubber designs can achieve the particulate standard of perfor-
mance. 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.
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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 power 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 Mechanical Engineers
(ASME) test method, which generally reflects lower particulate loadings than
the EPA method. Reported values with the ASME method range bel.ow 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 low-
sulfur 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 coal-
fired units of 125 and 140 mW capacity, approached the S02 emission limit
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of 1.2 pounds per million Btu. This operation represents 73 percent re-
moval of S0? from fuel gases in instances where the bituminous coal con-
tains 3.0 percent sulfur by weight. One of the units was selected for
the EPA test program, resulting in a verification of the S02 removal
performance reported by the control system 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 demon-
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 applicable 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. Lims-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 purposes of these
standards. In Sweden, another lime-slurry system, utilizing a different ^
I A KT •"* r\ C'l^f
scrubber design, has been demonstrated on a 70,JS|f>-Btu-per-hour oil-fired 3^
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
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with a volumetric flow rate equivalent to a 120 JS8-Btu-per-hour steam- tj
electric unit. 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 tail-gas volume flow rate equivalent to a
vM^ 5
220;S3&-Btu-per-hour steam-electric unit. This system has been installed
at a^p?000,000-Btu-per-hour oil-fired power 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 maanesium
oxide scrubbing system is being installed to serve a 4^LiIJU jUiitfJ-Btu-per-
hour steam-electric generator and is scheduled for operation 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 S02 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-percent-sulfur oil to meet the new-
source performance standard, some increases in desulfurization capacity
will be required, as well as growth of low-sulfur imports and extensive
use of blending.
Host of the naturally occurring United States coal of 0.7 nercent sulfur
or less is located in the Rocky Mountain area. Shipping costs have thus
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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-gas cleaning probably will be the least expensive method for many
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 flue-
gas 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 offrstoichiometric
combustion individually have the potential of meeting the standards for
liquid and gaseous fuels.
Published test data from six tangentially fired units of^.DOOTWTO1 to
?.3*f^
IgggggSISL Btu per hour (320 to 330 mW) capacity utilizing flue-gas
recirculation, and from seven units of capacities ranqing from
-k *r.rv/0*
r^f-"1 rftftfffl n n P t u 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. ' An EPA
test on one of the six tangentially fired units utilizing flue-gas recircu-
lation verified the published data for these units burning natural gas and
fuel oil. Off-stoichiometric combustion is generally utilized to limit
emissions of nitrogen oxides from steam generators burning liquid fuels.
Emissions from eight oil-fired units ranging in capacity from
ssons r
7, S ~n ( 0 •
to ^jf.QfiBaaa. Btu per hour (132 to 480 mW) were reported in various
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publications at levels below the standard of performance for liquid
fuels. ' Combined methods show promise of much lower emission levels,
although these techniques have not been adequately demonstrated.
The NO standard for solid fuels is based on results from tangentially
A
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 manufac-
turers, indicate comparable results for tangential firing, and considerably
higher levels for wall-fired units.?>8 Combustion modifications have not
as yet been applied to solid-fuel units to any extent. The fact that
tangential firing alone reduces NO emissions in units burning coal, however,
A
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 units shows
that there is little difference in NO production between tangentially
A
fired and wall<-.fired steam generators when combustion modifications are
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 NO when
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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
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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
J\
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.
Particulate 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
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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 SCL 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 con-
sidered 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 Oxides
Nitrogen oxides combustion-modification economics are similar to those
for electrostatic precipitators, with capital .investment increases approach-
ing 7 percent as a maximum, and elevation in operating costs reaching 4 percent.
The capital investment should decline to 0 percent, however, as combustion-
modification becomes common practice and not a special modification. A few
coal-fired steam generator designs inherently produce high levels of NOX, and it
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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.
A
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, 65J10):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 NO 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.
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.2 -
SUMMARY OF PROPOSED STANDARDS
Standards of performance are being proposed that will limit participate
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 wet impingement
collectors.
The standards of performance would apply only to those incinerators used
to burn predominantly municipal solid wastes, e.g., household and commercial
paper, cardboard, garbage, 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 follows:
No more than 0.10 grain of particulates per standard 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 C0£, corresponds to the production
of 1.9 pounds of particulates per ton of solid wastes charged to the
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incinerator, and about 0.17 pound of particulates per 1000 pounds of flue
gas, corrected to 50 percent excess air.
EMISSIONS FROM INCINERATORS
An uncontrolled incinerator will emit considerably more particulates than
the standard allows. Available data indicate that, on the average, uncon-
trolled furnace gases contain about 1 grain of particulates per scf
dry gas at 12 percent C02.1>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- standards in existence, which are based on the test pro-
cedure of the American Society of Mechanical Engineers. Despite the numerical
difference, both standards will require approximately the same degree of
particulate control.
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Some state and local standards are corrected to a reference base of 50
percent excess air rather than 12 percent COp. Others are given in terms
of mass emissions per unit weight of solid waste charged to the incinerator.
All of these units can be interrelated if suitable gas and solid waste
analyses are available.
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 Pollution from Municipal IncinerationJ 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-energy 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 scrubber,
the designer guaranteed particulate emission levels consistent with the
proposed standard.
21
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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
i
per scf dry gas, corrected to 12 percent CO*- These values were the average
of three 2-hour sampling runs at each plant. One of the values was con-
firmed 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 per-
cent 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
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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,
3
corrected to 12 percent CO . Lower emissions of particulates are re-
ported for a small pilot installation operated by the City of Pasadena
(California) in 1960. 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 STANDARDS
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 themselves 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. Reported costs are
23
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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 of 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
savey.$.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-tpn-per-day water-wall furnace, incinerator costs are about
$4^l^^8 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 percent for a 300-ton-per-day plant.
-------
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
Management, 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
1 dollar per year, decreasing as furnace capacity increases.
REFERENCES
1. Systems Study of Air Pollution from Municipal Incineration. 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. Compilation of Air Pollutant Emission Factors. U.S. DREW,
PHS. National Center for Air Pollution Control. Durham, N.C. PHS
Publication No. AP-42. 1968. 67 p.
3. Private communication with 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
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TECHNICAL REPORT NO. 3 -
PORTLAND CEMENT PLANTS
SUMMARY OF PROPOSED STANDARDS
Standards of performance are being proposed for all new wet- and dry-
process portland cement production facilities. The proposed 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
1. 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 designated
as No. 1/2 on the Ringelmann Scale or 10 percent equivalent
opacity.
Particulate Matter from Clinker Coolers
1. No more than 0.10 pound of particulates per ton of solids fed
27
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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 basis.
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 finished-
product 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. Obser-
vations 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
23
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clinker coolers can release as much as 30 pounds of particulates per ton
1 S2,3
of raw material. ' ' Such installations are likely to be equipped only with
centrifugal dust collectors. The proposed standards would require owners
and operators 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
particul ate 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
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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 port!and
cement, entitled Atmospheric Emissions from the Manufacture of Portland
Cement.
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 foreign 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.
Participate 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 thefEPA
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
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with electrostatic precipitators was able to meet the proposed standards.
A test of a dry-process kiln controlled with a baghouse, however, showed
participate emissions of 0.20 pound per ton of feed, which is below the
proposed standard. Inspections were made of three additional kilns
controlled with baghouses. No visible emissions were produced from the
latter three kilns, although one wet-process kiln showed a moisture-
condensation 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 electro-
static 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 precipi-
tators would have to be more efficient and probably larger than units presently
installed in existing plants, since tests of the two kilns with electro-
static 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
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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,
4
they are likely to be the result of bag failure.
ECONOMIC IMPACT OF PROPOSED 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
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 electro-
static precipitators cannot be attributed entirely to air pollution
control because many of the devices are used for product recovery and
32
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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; electrostatic
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
precipitator is used. '
33
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For a new plant of 2.5 million barrels per year, using 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. 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 Triangle P ark, N. C. April 1971.
3. Guidelines for Control of Emissions from Cement Plants. Internal
Document. Environmental Protection Agency. Raleigh, N. C. 1970.
4. Personal communication from R. E. Frey, Vice President, Mikro Pul,
Summit, N. J. June 4, 1971.
5. Eli as, Jv.R. and J. M. Dement. The Financial Impact of Air Pollution
34
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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.
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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 used to produce strong
acid by extraction or evaporation of weak acid, or by the direct strong-
acid 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 NO per metric ton,
J\
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 concentra-
tion 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.
i
37
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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 concen-
tration 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,
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-called "decolorizers" 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 NO emission regulations in the United States
A
that apply specifically to nitric acid production. Ventura County,
California, has enacted a limitation of 250 ppm NO that governs nitric
/\
2
acid plants as well as steam generators and other sources.
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
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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.
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 ammonia-
oxidation process. Natural gas or hydrogen-rich fuel is burned in the
gas stream to raise the temperature and to remove excess oxygen prior
to catalysis. Nitrogen oxides are destroyed in a stepwise process. Initially,
N02 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
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tail gases.
A survey of the ten plants in the United States that are equipped with
these 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 hydrogen-
rich purge gas from an adjacent ammonium nitrate plant. The third plant
.burned natural gas. During the EPA tests, NOY emissions from each of
^\
the three facilities were consistently lower than the maximum levels of
the performance standards. Measurements were conducted with continuous-
NO -monitoring devices, and values were confirmed by the phenoldisulfonic
A
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
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the NC>2 was converted to colorless NO. Thus, any facility meeting the
mass NOX limit will produce no visible 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 regulation 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 abate-
ment 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.
The standard of performance represents full control and is insensitive
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
decomposition 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
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months to several years. Cost estimates for a modern 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 Povey, 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
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TECHNICAL REPORT NO. 5 -
SULFURIC ACID PLANTS
SUMMARY OF PROPOSED STANDARDS
Standards of 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 SC>2 control
systems, or to chamber process plants or acid concentrators.
i
The proposed standards establish limitations on sulfur dioxide and acid
mist 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 ($02) per ton of acid
(100 percent H^SO.) produced or 2.0 kilograms S02 per metric ton.
Acid Mist
1. No more than 0.15 pound of acid mist (measured as ^SO*) per ton
of acid (100 percent H-SOJ produced or 0.075 kilogram acid mist
per metric ton.
2. No visible air pollutants shall be released to the atmosphere.
43
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The standard allows about 0.3 percent of the feedstock sulfur to
be released to the atmosphere as SO,,. For a typical plant, the sulfur
dioxide standard is equivalent to an exit-gas concentration of 280 ppm.
Where rich S02 streams (greater than 8.0 percent) are processed, the
equivalent concentration will be greater than 280 ppm. Conversely,
where weak SOp 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 rug 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 plant 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 SO-
by volume, or 21.5 to 85 pounds of S02 per ton of acid produced. Several
state and local agencies limit SOp 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 HpSO. 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 cooperative 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.
Much reliance necessarily had to be placed on the two demonstrated SC>
removal processes and on the single domestic application of each process
to full-scale acid production facilities. Tests of the two plants for
both acid mist and SCL 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: (1) a plant
of typical dual-absorption design and (2) a conventional single-absorption
spent-acid-burning plant that uses a sodium sulfite-bisulfite scrubbing
process to recover SCL from tail gas. The dual-absorption plant keeps
45
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SOp emissions low by converting more of the feedstock sulfur to sulfuric
acid. Other processes in use can control SCL 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 success-
fully in Europe for several years use both elemental sulfur and roaster
gas as feed. The literature reveals that three of these plants produce
maximum emissions ranging from 1.2 to 3.1 pounds of SO,, per ton of acid
produced, or 91 to 260 ppm SOp 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 SOp emissions normally do
not exceed the limits of the performance standards. During EPA tests,
the facility was being operated at only 52 percent of rated production
and S02 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 SOp emissions
to be consistently less than 4.0 pounds of SOp 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, SOp 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
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operation. Tests of this plant by EPA personnel have shown emissions
of 2.6 to 2.9 pounds of SCL 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 SC 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 SCL per ton of acid produced, or about
500 ppm. As operators 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-efficiency acid-mist
eliminators, including both fiber demisters and wire and tube electro-
static precipitato.rs. Fiber demisters are more commonly employed in
the industry.
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The standard for new sources is based principally on stack tests con-
ducted 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 (SO-,) and acid vapor. (The
latter two materials are sometimes considered under the collective
term "acid mist.") Acid vapor and S03 are converted to acid mist on
cooling and/or moisture absorption.
Inasmuch as new plants will be required to install either the dual-
absorption 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
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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 States.
Sulfur dioxide control systems represent a significantly greater capital
investment than acid mist collectors. Nevertheless, SOp 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 S02 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 SC^-scrubbing system, such as the sulfite-
bisulfite process. A dual-absorption plant with a 700- to 750-ton-per-
day 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
investment.
A new single-absorption plant, of the same capacity, with a sodium
sulfite-bisulfite scrubbing process attached may cost 35 percent
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more than an uncontrolled plant. The S02-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-ton-
per-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. Chemico 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.
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