U.S. Environmental Protci.lmn Agfncy Industrie1 Environmental Ht-'seaich
Office of Research and Development L dtxiratory
hVv.irrti Tri.iiiglt- f'drk, Nurth ( .irolui.i 2/711
EPA-600/7-77-077
July 1977
ERA'S STATIONARY SOURCE
COMBUSTION CONTROL
TECHNOLOGY PROGRAM--FY 1976
Interagency
Energy-Environment
Research and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S.
Environmental Protection. Agency, have been grouped.into seven series.
These seven broad categories were established to facilitate further
development and application of environmental technology. Elimination
of traditional grouping was consciously'planned to foster.technology
transfer and a maximum interface in related fields. The seven series
are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
This.report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from
the effort funded under the 17-agency Federal Energy/Environment
Research and Development Program. These studies relate to EPA's
mission to protect the public health and welfare from adverse effects
of pollutants associated with energy systems. The goal of the Program
is to assure the rapid development of domestic energy supplies in an
environmentally—compatible manner by providing the necessary
environmental data and control technology. Investigations include
analyses of the transport of energy-related pollutants and their health
and ecological effects; assessments of, and development of, control
technologies for energy systems; and,.integrated assessments of a wide
range of energy-related environmental issues.
REVIEW NOTICE
This report has been reviewed by the participating Federal
Agencies, and approved for publication. Approval does riot
signify that the contents necessarily reflect the views and
policies of the Government, nor does mention of trade names
or commercial products constitute endorsement or recommen-
dation for use.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
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EPA-600/7-77-077
July 1977
ERA'S STATIONARY SOURCE
COMBUSTION CONTROL TECHNOLOGY
PROGRAM--FY 1976
by
Acurex Corporation/Aerotherm Division
485 Clyde Avenue
Mountain View, California 94042
Contract No. 68-02-2160
Program Element No. EHE624A
EPA Project Officer: Joshua S. Bowen
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, N.C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
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TABLE OF CONTENTS
Section Page
1 INTRODUCTION . 1
2 PROGRAM OVERVIEW 2
2.1 Program Rationale 5
2.2 Program Objectives 6
2.3 Approach 6
2.4 Program Benefits 8
3 CURRENT PROGRAM STATUS 9
3.1 Field Testing and Environmental Assessment 10
3.1.1 Utility Boiler/Power Generation Equipment Field
Testing 11
3.1.2 Field Testing of Industrial Boilers 12
3.1.3 Field Testing of Industrial Process Equipment .... 13
3.1.4 Residential/Commercial Heating Systems Testing ... 13
3.1.5 Environmental Assessment and Systems Analysis of NO
Combustion Modification Technology 16
3.2 Process R&D 17
3.2.1 Combustion Modification for Utility Boilers 17
3.2.2 Combustion Modification for Industrial Boilers ... 19
3.2.3 Combustion Modification for Residential/Commercial
Heating Systems 19
3.2.4 Stationary Engine Combustion Technology 20
3.2.5 Industrial Process Equipment and Afterburners .... 23
3.2.6 Fluidized Bed Combustion Support 23
3.3 Fuels Research and Development 24
3.3.1 Improved Burner/System Design 24
3.3.2 Advanced Combustion Modification Techniques 24
3.3.3 Catalytic Combustion 29
3.3.4 Alternate Fuels 29
3.4 Fundamental Studies 30
3.4.1 Combustion Chemistry 32
3.4.2 Combustion Aerodynamics 35
3.4.3 Application for Combustion Control 36
APPENDIX A - EPA/IERL-RTP REPORTS ON NO
COMBUSTION MODIFICATION . ? 37
APPENDIX B - CONVERSION FACTORS 45
m
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FIGURES
Page
Summary of 1974 Stationary Source NO Emissions 2
/\
Scotch Marine Boiler (60 hp) for Emission Control
Equipment Evaluation 15
225-KW Gas Turbine Used for IERL-RTP In-house Studies ... 21
Precombustion Chamber Diesel (300 hp) for Stationary
Engine Controls Development 22
Multiburner Experimental Furnace (3 million Btu/hr) ... 26
Full-scale Burner Test Facility (125 million Btu/hr) ... 28
Experimental System for Combustion Modification and
Future Fuel Studies 31
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SECTION 1
INTRODUCTION
This report presents the highlights and accomplishments of the
Combustion Research Branch (CRB), Industrial and Environmental Research
Laboratory, Research Triangle Park (IERL-RTP) for the calendar year 1976.
The objective of the CRB is the character!' zati on * assessment, and control
of the environmental impact of energy conversion technologies. Programs
are underway to identify the multimedia pollution problems associated with
combustion processes (i.e., related to residential, commercial, industrial,
and utility boilers, industrial process combustion equipment, and stationary
gas turbine and reciprocating 1C engines) utilizing conventional fossil and
alternate new fuels.
The major goals of these efforts are the development and demonstra-
tion of combustion modifications and control techniques or devices to pre-
vent or minimize pollution problems for these processes in a cost-effective,
energy-conserving, process-efficient, and environmentally acceptable manner.
Although the major emphasis of the program is on investigation of technology
for control of oxides of nitrogen (NOX), efforts are also underway to reduce
or eliminate other pollutants (such as hydrocarbons, carbon particulate,
smoke, carbon monoxide, and various potentially hazardous trace and minor
species) while simultaneously maximizing system efficiency by optimizing
system design and operating characteristics.
Combustion sources contribute about 98 percent of the total NO
A
emissions from stationary sources. Some NOX is formed in all fossil fuel
combustion processes. Recent estimates of NO emissions from major source
A
categories in 1974 are shown in the following figure. Control technology
development studies indicate that combustion modification is the primary
near-term method of controlling NO emissions from the combustion of fossil
A
fuels.
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UTILITY
BOILERS
47.8%
INDUSTRIAL
BOILERS
17.7%
INCINERATION 0.4%
OTHERS 1.6%
GAS TURBINES 1.6%
NONCOMBUSTION 1.7%
INDUSTRIAL PROCESS 2.9%
HEATING
SOURCE
UTILITY BOILERS
INDUSTRIAL BOILERS
RECIPROCATING 1C ENGINES
COMMERCIAL/RESIDENTIAL HEATING
INDUSTRIAL PROCESS HEATING
NONCOMBUSTION
GAS TURBINES
INCINERATION
OTHER
TOTAL
ESTIMATED NOX EMISSIONS
TONS/year
5,814,000
2,153,000
2,140,000
1,069,000
350,000
224,000
190,000
43,400
192,000
12,175.4qp_ _
Summary of 1974 stationary source NO emissions
A
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Following provisions of the 1970 Clean Air Act amendments, the EPA,
in 1971, promulgated a primary and secondary National Ambient Air Quality
Standard (NAAQS) for N0« of 100 yg/m3 (annual average). The EPA NO abate-
£. A
ment strategy to achieve and maintain the NAAQS focused on 90 percent re-
duction of NO emissions from light duty vehicles by 1976 as mandated by
A
the Clean Air Act. Stationary sources were to be regulated through the
application of reasonably available control technology under the Federal
Standards of Performance for New Stationary Sources and, where required,
under the State Implementation Plans for existing sources. The sufficiency
of EPA's ongoing stationary source NO control development program to meet
/\
the needs of the NO abatement strategy was contingent upon the implementa-
/\
tion of the statutory standard of 0.25 mg NO^/m (0.4 g NO^/mile) for light
duty vehicles.
Until recently, it appeared that existing or a low level of develop-
ment of stationary source control technology would be adequate to achieve
and maintain air quality in the 1980 to 2000 period. However, since 1973,
the energy shortage and changes in the national NO abatement strategy have
A
placed additional demands on the stationary source control technology.
Specifically, consideration must now be given to the following factors:
• Decreased reliance on mobile source emission reductions
• Increased awareness of potential multimedia environmental impacts
from stationary source combustion and NO controls
A
• Recognition of the need for advanced stationary source controls
to account for energy growth demands between 1980 and 2000
t Accelerated development of alternate fuels and combustion pro-
cesses
• Extensive fuel switching to coal
t Increased fuel and equipment costs causing reassessment of eco-
nomic and energy consumption trade-offs for various options
Present CRB activities to address the above needs are divided into
the following elements: field testing and environmental assessment, pro-
cess research and development, fuels research and development, and funda-
mental studies. Field testing is directed toward the determination of the
3
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range of NO control possible in existing equipment, and environmental
A
assessments identify the multimedia environmental impact of stationary com-
bustion sources and NO control systems for attainment and maintenance of
A
current and projected air quality standards. Process R&D encompasses the
development and demonstration of optimum NO control technology for existing
A
and new combustion systems. Fuels R&D studies are designed to develop
generalized combustion control technology which is applicable to the con-
trol of NO and other pollutant emissions from the combustion of conven-
A
tional fuels, waste fuels, and future fuels. Fundamental studies provide
an understanding of the important phenomena in the formation and destruction
of pollutants during combustion which may then be utilized in pilot scale
equipment and fuels control technology.
The following section presents a general program overview and the
final section summarizes current activities of the Combustion Research
Branch in the above research categories. A program funding summary is
provided in Appendix A, and a tabulation of EPA reports relating to NO
A
combustion control is presented in Appendix B.
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SECTION 2
PROGRAM OVERVIEW
Nitrogen oxides (NO ) are among the atmospheric pollutants for which
A
standards and regulatory controls have been enacted by both the EPA and
state and local agencies. The regulations result from the quantity of NO
A
emitted by both mobile and stationary sources and from the recognition of
the potential for widespread adverse public health and welfare effects.
Atmospheric NO emissions undergo complex photochemical reactions in com-
A
bination with selected hydrocarbons and sulfur oxides to form precursor
species of smog and other deleterious substances.
2.1 PROGRAM RATIONALE
Stationary sources account for over half of the total man-made NO
A
emissions annually, and of the stationary source emissions, fuel combus-
tion is responsible for over 98 percent. Combustion generated NO emissions
A
result from both thermal fixation of nitrogen in the combustion air (thermal
NO ) and conversion of fuel bound nitrogen (fuel NO ). Thermal NO is
A A A
formed through a series of reactions which are strongly dependent on local
flame temperature and less dependent on oxygen availability. Fuel NO is
A
formed by the oxidation of organic nitrogen compounds through a series of
reactions strongly dependent on local oxygen availability and to a lesser
extent, on temperature. Thus, NO emissions can be strongly affected by
A
nitrogen containing fuels such as coal. Recent trends toward the use of
coal as a primary fuel have placed greater emphasis on NO control tech-
A
nology. The Esso R&E (Exxon) study of 1969 and subsequent updates identi-
fied combustion process modification as the most efficient as well as the
most cost-effective means of reducing combustion generated NO emissions
A
from stationary sources. CRB's combustion process modification activities
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are accordingly directed toward the characterization, assessment and
control of combustion generated air pollution, with particular emphasis on
N0x.
2.2 PROGRAM OBJECTIVES
The overall objective of the CRB's NO combustion modification pro-
A
gram contributes to the overall goal of the IERL which is the development
and demonstration of cost-effective technologies to prevent, control, or
abate pollution from operations with multimedia environmental impacts
associated with the extraction, processing, conversion, and utilization of
energy and mineral resources. Further objectives are the identification
and evaluation of environmental control alternatives of those operations
as well as the assessment of associated environmental impacts. The overall
IERL-RTP goal in stationary source air pollution control development can
be divided into four specific objectives:
• To describe at least one method for control of each major source
of pollution
t To provide a technical base for EPA's enforcement activities
t To establish technical and economic data to support New Source
Performance Standards (NSPS)
• To provide information required to make environmentally sound
decisions on energy development policy
2.3 APPROACH
IERL-RTP1s combustion modification activities relating to NO and
A
other combustion generated pollutant control work within the following
framework:
• NO Environmental Assessment/Applications Testing - determination
A
of the environmental emissions of NO and other combustion re-
A
lated pollutants from stationary combustion sources. Evaluation
of the environmental effectiveness and impact (as compared to
the uncontrolled state) of combustion control modifications
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including alternative operating conditions, minor retrofit con-
trol, extensive retrofit control for existing units, and
optimized design for new units, or selection of an alternate
low-NO process.
A
t Development of Combustion Modification Technology for NO -
/\
development and demonstration of practical combustion modifica-
tion technology for controlling NO and related combustion
X
generated pollutants from utility boilers, commercial boilers,
industrial boilers, residential heating systems, industrial
combustion equipment, stationary engines, and advanced processes.
Since over 98 percent of the NO emissions from stationary sources
J\
are formed during the combustion of fuels, the logical approach to control
is the modification of the conditions under which fuel combustion takes
place. The techniques which can be used are now well documented and,
depending on a variety of factors, offer potential for substantial control
of NO (50 to 90-plus percent). In addition, these techniques can be
/\
optimized to reduce or eliminate emissions of other pollutants (such as
CO, hydrocarbons and carbon particulate) and to increase system efficiency
by careful attention to system design and operating characteristics.
This approach to control NO builds on a solid technology base for
/\
conventional fossil fuels and provides for the further generation of new
technology for both conventional and alternate fuels. The emphasis is on
source-specific field application of control techniques ranging from minor
hardware changes on existing sources to establish short-term control tech-
nology to complete system redesign for optimizing all energy and emission
aspects of an equipment class. The field application studies are supported
and guided by activities in: generalized burner and control system develop-
ment, advanced process development based on novel concepts, evaluation of
emissions aspects of alternate fuels, and fundamental and analytical re-
search.
Field application of techniques for many optimized conventional
fossil fuel combustion systems will be completed by the early 1980s, and
design criteria for alternate fuels and advanced systems will be developed
and partially demonstrated by that time. Due to lags between development
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and application of technology attributable to normal scheduling and logistic
considerations, it can be expected that field application of concepts in
the latter class will be accomplished between 1980 and 1985. In carrying
out this program, a combination of numerous contract, research grant, inter-
agency, and in-house projects are being undertaken.
2.4 PROGRAM BENEFITS
Several far-reaching benefits will result from the NO combustion
A
modification/control program on a near- and long-term basis.
The primary benefit of the program will be an improvement in air
quality which is directly affected by NO emissions. Several indirect bene-
X
fits will be realized as a result of improved air quality. Decreased health
effects, such as respiratory diseases which have been related, either di-
rectly or indirectly, to air pollution rank as the primary indirect benefits.
The second major benefit will be the impact upon national energy sup-
plies. Presently, the trend toward nationally abundant coal has been re-
tarded, in part, as a result of nonexistent, uneconomical, or inadequate pol-
lution controls. Successful combustion modification techniques will allow
increased flexibility for the use of coal as a major source of energy. Fur-
ther still, two secondary benefits derived from combustion modifications are
the potential reduction of the emissions of other undesirable pollutants and
a potential increase in system efficiency.
A third major benefit again relates to the national energy picture.
Successful combustion control development will result in a further increase
in the use of coal as a fuel for stationary sources allowing the cleaner
fuels to be used for applications where control is less feasible. This is
particularly true for mobile sources where the difficulties of pollution con-
trol technology have required the continued use of gasoline and diesel fuel.
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SECTION 3
CURRENT PROGRAM STATUS
The present NOY combustion modification program at the Combustion Re-
/\
search Branch can be divided into four major elements:
• Field Testing and Environmental Assessment
t Process Research and Development
• Fuels Research and Development
• Fundamental Studies.
A further element of the program is the efficient dissemination of
technical information from its research activities to control developers,
equipment manufacturers and users, and the authorities involved in setting
and enforcing standards. Two practices have been initiated to establish an
efficient means of technology transfer: (1) Symposia and (2) "Newsletters".
The first symposium on Stationary Source Combustion took place in
Atlanta in September 1975, and the next meeting is scheduled for New Orleans
for August 29 through September 1, 1977. Sessions were held in the key pro-
gram areas of the CRB. The Fundamental Research session highlighted results
from ten analytical and experimental studies of pollutant formation and re-
duction and concluded with a panel discussion on "Combustion Chemistry and
Modeling". Developments in external combustion control, burner modifica-
tions, combustion of alternate fuels and alternate combustion concepts were
presented in the Fuels Research and Development session. The Process Re-
search and Development session highlighted development of advanced NO con-
^
trol technology through minor hardware changes to existing equipment which
will provide guidelines for low NO new unit design and for retrofit field
A
implementation of NO controls. The final session, Field Testing and Survey,
/\
contained seven papers on uncontrolled emission characterization and on
-------
control achieved by alteration of operating conditions. The proceedings of
the Atlanta meeting have recently been published as an EPA report.
The first issue of a "newsletter," entitled "NO Control Review," was
/\
published in March 1976. Issued approximately quarterly, the Review presents
the status of stationary source NO control technology and related topics.
A
Each issue leads off with major recent developments or topics of general in-
terest; the remainder is divided into the following topical categories: con-
trol R&D, control implementation, alternate processes, flue gas treatment,
regulatory strategies, technical briefs, recent publications, and a calendar
of upcoming meetings. Future issues will include a listing of applications
of NO control technology to major utility and industrial stationary combus-
J\
tion sources.
3.1 FIELD TESTING AND ENVIRONMENTAL ASSESSMENT
The field testing element includes studies designed to determine the
potential for control of NO emissions from existing equipment. This work
A
is generally performed by R&D organizations familiar with the specific com-
bustion systems being studied, and with the financial and technical assis-
tance of manufacturers, users, and trade associations. The field testing
and survey studies are the initial efforts in the development of control
technology and are designed to demonstrate the state of the art in control of
NO and combustible emissions. In addition to developing trends and provid-
ing application guidelines for industry to minimize emissions with present
technology, the work also suggests where R&D efforts should be concentrated
by developing emission factors as a function of equipment type and size, and
fuel consumed.
The environmental assessment component of the program element focuses
on identification of the multimedia environmental impact of stationary com-
bustion sources and NO controls and, for this impact, identifies the most
/\
cost-effective, environmentally sound NO control systems for attainment ard
A
maintenance of current and projected ML air quality standards. This activ-
ity provides program guidelines for development of NO controls sufficient to
A
assure compliance (to the year 2000) with air quality standards in critical
air quality control regions.
10
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3.1.1 Utility Boiler/Power Generation Equipment Field Testing
lERL-RTP's NO control program was initiated in 1970 when Exxon R&E
A
began field testing utility boilers to define baseline emissions and estab-
lish the effect of combustion modification techniques. It was found that
NO emissions from gas- and oil-fired boilers could be reduced by 50 to 60
/\
percent by using combustion modification techniques such as low excess air
firing, staged combustion, flue gas recirculation, load reduction, air pre-
heat reduction, change in burner tilt, and change in primary to secondary
air ratio. Of these, the first two were found to be most applicable and
cost effective. Combustion modification with coal-fired boilers was less
successful for NO reduction and more difficult because of operating prob-
A
lems. Since the Exxon systems study identified coal-fired utility boilers
as the top ranking source of NO emissions from stationary sources, efforts
A
were concentrated on these units. Further Exxon studies showed that reduc-
ing the excess air level and employing staged combustion, as with gas- and
oil-fired boilers, resulted in significant NO reductions, averaging about
A
40 to 50 percent for the boilers tested. The degree of reduction, as well
as baseline NO emission levels, varied with the design and size of coal-
X
fired boilers tested and with coal type. No extreme differences in flue gas
particulate loadings and in the carbon content of the flyash were found dur-
ing the boiler tests.
A subsequent extension to the Exxon field test program of utility
power generation equipment includes trace specie emission measurements and
testing of an additional six units including a carefully controlled investi-
gation into the effects of NO controls on tube wastage in coal-fired boilers.
A
Emission measurements will be made of sulfates, nitrates, HCN, HC1, ROM's,
and PCB in addition to the original NO, N02, S02> S03> CO, C02, 02, UHC, par-
ticle loading, and particle size distribution. The additional test sites
extend previous emission characterizations and control tests to a broader
range of design types and operating conditions. Corrosion tests will be con-
ducted on a 500 MW horizontally-opposed, dry-bottom coal-fired boiler with an
initial 4-month baseline test to establish normal tube wastage rates followed
by a 6-month run in which low NOV conditions will be accomplished through low
A
excess air firing and staged combustion via burners out of service. The tests
will use a new ultrasonic tube thickness sensor (accurate to ± 0.0001 inch),
11
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corrosion coupon probes, and replaceable tube wall panels with before and
after metallographic characterization.
A new program is being initiated to conduct long-term comprehensive
emissions and corrosion tests on coal-fired utility boilers designed to meet
the New Source Performance Standards for NO of 301 ng NO-/J (0.7 Ib N09/106
A C. £•
Btu) heat input. Each test boiler will exceed 125 MW in capacity and burn
high sulfur bituminous coal. It is expected that these tests will fully
quantify the effects of NO combustion modification on emissions, corrosion,
/\
boiler performance, and reliability for major coal-fired boiler design types.
Future work with utility boilers will continue to concentrate on coal-
fired units, but will also consider firing of mixed fossil fuels (e.g., coal
and oil, or gas and oil) fired simultaneously, coal-derived fuels (e.g., low-
Btu gas and solvent refined coal), and waste fuels. Tests are also underway
with other power generation equipment such as gas turbines and large internal
combustion engines.
3.1.2 Field Testing of Industrial Boilers
In 1973, a major field test program with industrial boilers was initi-
ated. KVB Engineering was awarded a contract to test approximately 50 gas-,
oil-, and coal-fired boilers, ranging in size from 10,000 to 500,000 pounds
of steam per hour during the first year. Measurements included efficiency
and emissions of NO , SO , HC, CO, smoke, and particulate mass. The tests
X X
were short-term and concentrated on operating variables such as excess air,
load, swirl adjustment, and primary, secondary, and tertiary air adjustment.
During the second year, 18 boilers were tested in more detail with more exten-
sive modifications, such as overfire air, flue gas recirculation, and varia-
ble air preheat temperature. Also, particle size distribution and (on approx-
imately five oil- and coal-fired boilers) trace specie emissions were measured.
The 2-year study provided the following data on uncontrolled baseline emis-
sions: 164-922 ppm, 65-619 ppm and 50-375 ppm for coal, oil and gas firing,
respectively. Corresponding baseline operation emission averages were 275
ppm, 120 ppm, 293 ppm, 269 ppm and 139 ppm for coal, #2 oil, #5 oil, #6 oil,
and natural gas. Excess air, burners out-of-service and flue gas recircula-
tion proved to be the most effective combustion modification techniques for
12
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reduction of NO emissions without sacrificing boiler efficiency. NO re-
A A
ductions up to 35 percent without increases in particulate emissions were
experienced with low excess air firing. Flue gas recirculation reduced NO
A
by 10 to 40 percent, but increased particulate by 5 percent and boiler effi-
ciency was slightly reduced. The burners out of service technique reduced
NO up to 54 percent without reduction in efficiency, but particulate emis-
A
sions always increased. A final report was recently completed on the second
phase of this project, and the study will culminate in the issuance of in-
structional guidelines for low emission operation and design of industrial
boilers.
3.1.3 Field Testing of Industrial Process Equipment
IERL-RTP has contracted with KVB to conduct a 1-year field test pro-
gram for industrial process equipment, gas turbines, and internal combustion
engines. Emphasis is on detailed emission characterization of a representa-
tive group of furnaces, kilns, ovens, and dryers, firing coal, oil, gas, waste
fuel, and mixed fuels. Measurements will be made of NO, S02, SO-, 0^, CO,
C0£, HC, particle size and grain loading, opacity, and where relevant, trace
metallics and trace organics (POM, PCB). KVB will also assess the degree of
emission control achievable from modification of operating parameters such
as unit load, excess air, and combustion air preheat. The gas turbine tests
will assess the use of water injection as a means of NO control. A total of
A
25 units will be tested.
3.1.4 Residential/Commercial Heating Systems Testing
In an IERL-RTP sponsored effort, Battelle has recently completed work
on guidelines for residential and commercial oil burner adjustments. Intended
for use by service managers for service training and by skilled service tech-
nicians in their oil burner service work, the adjustment guidelines are impor-
tant because they ensure reliable automatic operation, provide for efficient
fuel utilization and minimize air pollution. In addition, the guidelines
also include appendices with background material on pollutants of primary con-
cern, field-type instruments and significance of measurements, fuel oil
characteristics, and emission characteristics of residential and commercial
oil burners and boilers.
13
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A pamphlet produced in-house entitled "Get the Most From Your Heating
Oil Dollar -Servicing Cuts Cost and Pollution" is being distributed to home-
owners throughout the U.S. It is designed to transfer emissions and fuel
conservation technology developed during field tests of residential equipment
directly to the public.
In-house studies closely related to the field testing are being con-
ducted on emission characterization and design evaluation for commercial com-
bustion systems. The objective of this work is to investigate, under con-
trolled laboratory conditions, the emission performance of existing/prototype
commercial combustion systems and components and to evaluate effects of new
burner/combustor designs and modifications on the emission and energy effi-
ciency performance. Two different equipment systems have been baselined;
that is, the best conditions for minimum emissions with unaltered equipment
have been established. These systems include two major types of firetube
packaged boilers: Scotch marine and firebox.
The Scotch marine firetube boiler has been utilized for the study of
two fuel-oil/water emulsion devices: The Cottell Ultrasonic Emulsifier and
the Total Emulsifier. The Cottell device provided significant reductions in
smoke number and particulate emissions. The Total device provided signifi-
cant reductions in particulate when firing distillate-oil/water emulsions,
but smoke increased because the particle size distribution shifted to a
smaller size. Neither emulsifier reduced NO emissions significantly when
A
firing residual oil (which has a high-fuel nitrogen content); however, a
significant NO reduction was observed when distillate oil was fired. On-
A
going tests on the Elf Union (a French oil company) emulsion burner with a
capability of 10-70 gph capacity have not resulted in data as yet. Some
emulsion devices may have a small potential for energy conservation by per-
mitting boiler operation at lower excess air levels, but this may require
trading back the emission improvements.
In addition to the basic emission characteristics, a number of design
and equipment changes have been studied. A burner redesign program was suc-
cessful in reducing CO, HC, and smoke emissions from the firebox/firetube
package boiler without increasing NO emissions. A fuel injection equipment
A
program has been carried out to determine emission characteristics from air,
high pressure, and sonic atomization of No. 6 residual oil.
14
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Scotch marine boiler (60 hp) for emission control equipment evaluation
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A comprehensive sampling and analytical system for use on IERL-RTP
in-house equipment facilities is being developed by Aerotherm and A. D. Little.
The system consisting of a specialized source assessment stack sampler and a
complete analytical chemistry lab, is presently in the design phase. Design
completion is expected in late 1976 or early 1977.
3.1.5 Environmental Assessment and Systems Analysis of NOX Combustion Modi-
fication Technology
A major contract award has been made to the Aerotherm Division of
Acurex Corporation for a multimedia environmental assessment and system
analysis of NO combustion modification techniques. This effort is to deter-
A
mine the technical soundness and environmental acceptability of these control
methods, and to ensure that any deficiencies or potential problems are identi-
fied and corrected in a timely fashion, before the technologies are adopted
commercially.
The general technical approach in this project is based on the need to
provide efficient and timely assessments of near-term control technologies
while maintaining a comprehensive treatment of likely control needs to the
year 2000. Throughout the program, emphasis will be given to synthesis of
existing and emerging technology on control systems, trace emission and pol-
lutant transport transformation and impact. The major project effort will
go toward the compilation and evaluation of data from past and ongoing pro-
grams for the EPA and other agencies. Additionally, the environmental assess-
ment activities will be coordinated with the IERL-RTP guidelines developed
for the numerous ongoing source and environmental assessments. The evalua-
tion of potential air quality standards and N02 abatement strategies will be
coordinated with the Office of Air Quality Planning and Standards (OAQPS) as
well as the several task forces established to define mobile source emission
control needs. The intent of this evaluation is to obtain an objective over-
view of the future needs for combustion modification NO controls.
/\
The approach and level of effort allocated to project tasks is base^
on prioritization of sources, controls, pollutants, and Air Quality Control
Regions (AQCR). The basis of the prioritization is to focus the study on de-
velopment needs for environmentally sound control systems. Throughout the
program, emphasis will be given to those sources, controls and multimedia
16
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impacts most likely to be involved in control implementation in critical
AQCR's up to the year 2000. Early use of the systems analysis models will
aid in setting the program priorities. A screening approach will be used in
the systems analysis whereby a simple model will be used to prioritize the
options. More sophisticated models will be introduced for verification as
process and emission data become available.
The effort will be time-phased on a descending priority basis with
early emphasis on near-term sources and controls. Subsequent updates will
be made to maintain a current assessment of the high priority areas. This
approach requires parallel initiation of all program elements with early em-
phasis on gathering results from previous efforts and later emphasis on syn-
thesis or generation of new data.
3.2 PROCESS R&D
lERL-RTP's process research and development work involves the appli-
cation of optimum NO control technology to existing and new combustion sys-
A
terns. The results of these studies provide the basis for the demonstration
of combustion control technology. During the past year, interest in projects
in this area has continued to develop.
3.2.1 Combustion Modification for Utility Boilers
In a study being conducted by Combustion Engineering, Inc., a 400 MW
tangential utility boiler equipped with factory-installed overfire air firing
western bituminous "B" coal yielded NO emissions as low as 189 ng NO?/J
/\ (—
(0.44 Ib N02/106 Btu), which is below the Standard of Performance for New
Stationary Sources of 301 ng N02/J (0.7 Ib N02/106 Btu). Baseline N0x emis-
sions for this unit, without the use of the overfire air system, ranged from
258 to 301 ng N02/J (0.6 to 0.7 Ib N02/106 Btu) at normal excess air levels.
Further tests evaluated the effect of total excess air, overfire air rates
and tilts, burner tilt, wall slag and unit load. A 25 percent NO reduction
A
from baseline was observed at normal, total excess air levels (26.2 percent)
with the primary flame zone operated at 105 percent of stoichiometric. Slag
buildup produced a negligible increase in NOY under staged conditions. As
y\
with baseline conditions, NO increased with unit load. Carbon heat losses
/\
of 0.2 to 0.6 percent resulted during staging. This level corresponds
17
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to the losses experienced under normal firing when operating below 15 percent
excess air. Similar tests are now being conducted on a unit firing western
sub-bituminous "C" coal. A final report on these two tests should be complete
by late 1976.
Under an interagency agreement with IERL-RTP, TVA has evaluated biased
firing on a 125-MW wall-coal-fired utility boiler. The tests indicate that a
30 to 50 percent NO reduction could be obtained for wall-coal-fired units
/\
depending upon load and burner configuration. Biased firing increases the
carbon losses in the particulate causing a reduction in the ash conductivity
which could affect ESP performance. The increases, however, were not deemed
significant. Boiler efficiency is reduced over the entire load range under
biased firing conditions. Data from 1 month tests using specially designed
corrosion probes indicate accelerated tube wastage rates on the side walls,
but the statistical significance of these results is currently in question.
Aerospace Corporation, under IERL-RTP sponsorship, has compiled and
correlated field test data collected by the Los Angeles Department of Water
and Power for some of their gas- and oil-fired utility boilers. A report on
the extension of this effort to include coal-fired utility boilers is now in
preparation. In addition to correlating emission data with combustion modi-
fication techniques, Aerospace has performed a combustion stability analysis
to determine how a boiler can be redesigned to allow more flexibility in the
use of combustion modifications. Aerospace is also generating a stationary
source emissions inventory to the year 1975 and emissions projections to the
year 1985. A final report has recently been completed.
Monsanto Research Corporation is currently preparing a report based on
a study of utility and industrial coal-fired cyclone boilers. The objective
of the study was to assess the need and the potential for controlling NO emis-
A
sions from existing coal-fired cyclones. The final report will provide a
population and geographic distribution with NO emission rates from several
A
sources, as well as definition of available combustion modification techniques.
Results will include projections of potential NO reduction through combustion
/\
process modifications and estimates of R&D costs to develop corresponding
retrofit controls.
18
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3.2.2 Combustion Modification for Industrial Boilers
KVB, under contract to IERL-RTP, tested 10 intermediate sized (10,000
-300,000 pph), pulverized coal and stoker fired boilers to determine the fea-
sibility of substituting low sulfur western sub-bituminous coal for high sul-
fur eastern bituminous coal primarily as a means of reducing sulfur oxide
emissions. The resulting impact on NO was also assessed. Major emphasis
/\
was placed on stoker units as pulverized coal units in this capacity range
are less prevalent. Lower NO emissions were measured on both pulverized
A
coal units and stokers as a result of the lower fuel nitrogen content of the
coal and of the lower combustion temperatures due to the high moisture con-
tent of western coals. In general, the conversion of intermediate boilers
to western coals was found to be a feasible alternative. Guidelines for
conversion of a variety of design types to the use of western coals are in
preparation.
A contract program will be initiated in late 1976 to study potential
emission control technology for stoker coal fired industrial boilers. The
program will focus on the complete spectrum of emissions from the sources
and will develop technology to improve the environmental acceptability of
stoker boilers. This contract will expand the prior work on small stokers
to larger scale spreader stoker boilers and include a more comprehensive
assessment of processed coals.
3.2.3 Combustion Modification for Residential/Commercial Heating Systems
Battelle, under contract to IERL-RTP, completed a technical assessment
of increased utilization of stoker coal systems for residential and small
commercial space heating applications. The assessment was based on (1) an
experimental study evaluating emissions (including carcinogenic POM) from a
20 Hp boiler firing a variety of coals and processed fuel, (2) a survey to
identify equipment and manufacturers, and (3) a survey to identify processes
for the production of smokeless coals. The experimental research indicated
that modifications in design and operation of small stoker boilers has poten-
tial for emissions reduction and, coupled with utilization of processed coals,
could achieve improvements over existing equipment. However, the conclusion
was made that current economic and environmental factors are unfavorable for
increased utilization of coal in residential and small commercial applica-
tions.
19
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3.2.4 Stationary Engine Combustion Technology
A program recently initiated with Pratt and Whitney Aircraft is di-
rected toward the development of low NO gas turbine combustor technology.
A
The study will focus primarily on dry control techniques because of fuel
economy and operational considerations and will specifically address utility
size (25 MW and larger) gas turbine units. Since future gas turbines may be
required to burn heavier fuel oils or low-Btu gas containing significant
levels of ammonia, the contract will also address control of NO resulting
A
from the conversion of fuel nitrogen.
IERL-RTP has initiated an in-house investigation of stationary engine
emissions control. Two engines have been installed at the RTF laboratory:
a gas turbine and a precombustion chamber diesel. Experimental work to date
has concentrated on the gas turbine with initial indications that CO, HC,
and fine particulate emissions are serious problems in the unit. Determina-
tion of the baseline emission characteristics resulted in the NOo fraction
of total NO ranging from 45 percent at no load to a negligible amount at
A
rated load. The water/oil emulsion proved beneficial as a NO reduction
X
technique with a 33 percent reduction in NO and total NO with a 26 percent
A
addition of water. The water fraction is limited by the characteristics of
the emulsion to about 35 percent. At water injection rates sufficient to
appreciably reduce NO levels, CO levels could increase by as much as 20
y\
percent over the lowest emission rates.
Tests on the precombustion chamber diesel engine have recently begun.
The NO levels appear to be reduced by use of an oil/water emulsion, but
A
data are still being analyzed. A catalytic muffler will be tested with the
diesel in late 1976.
CRB is selecting a contractor for a new program in low NO 1C engine
A
development. The purpose of the new program is to investigate internal com-
bustion engine chamber design parameters effects on air pollutant emissions.
The goal is the development of a design giving substantial reductions in NO
/v
emissions for large bore stationary 1C engines while maintaining or improv-
ing current technology levels for CO, HC, and carbon particulate emissions
and fuel efficiency. Both new design and retrofit to existing engines will
be considered; designs will be developed for gas-fueled spark ignition and
oil fueled compression ignition 2- and 4-stroke engines.
20
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225-KW gas turbine used for IERL-RTP in-house studies
-------
ro
rv>
Precombustion chanter diesel (300 hp) for stationary engine controls development
-------
3.2.5 Industrial Process Equipment and Afterburners
The Institute of Gas Technology, under contract to IERL-RTP, has re-
cently completed a survey of industrial process combustion. The objectives
of the study were threefold: to identify the significant emission sources,
to investigate the potential for effective emission controls, and to compile
information on combustion equipment in use and future trends in process and
equipment design. The iron and steel, cement, glass, aluminum and petroleum
refining industries were identified as the major sources of combustion gen-
erated air pollution within the process combustion field. Recommendations
were presented for NO control R&D programs for each of the significant pro-
A
cesses within each industry.
A new program in 1976 will assess the pollution control and energy
conservation potential of afterburner combustion systems. The primary ob-
jective of this study is to assess the environmental status of afterburner
combustion systems and to develop guidelines for their application to mini-
mize environmental problems. The program will completely analyze the prob-
lem of emissions from afterburner combustion systems and result in a standard
of practice manual for applying these systems for emissions control without
creating additional environmental problems.
3.2.6 Fluidized Bed Combustion Support
A contract has been awarded to Aerotherm for the design and construc-
tion of a fluidized bed combustion (FBC) sampling and analytical test rig.
This small pilot-scale equipment will be installed and operated in lERL-RTP's
in-house combustion research laboratory. This project is to provide for:
comprehensive analyses of emissions from FBC, testing of alternative sampling
and analytical procedures for FBC, and investigation of alternative add-on
environmental control devices for FBC. Conceptual design has been completed,
and installation and shakedown at IERL-RTP are scheduled for completion in
mid-1977.
23
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3.3 FUELS RESEARCH AND DEVELOPMENT
Fuels research and development studies are designed to develop gen-
eralized combustion control technology which is applicable to the control
of NO and other pollutant emissions from the combustion of conventional
A
fuels, waste fuels, and alternate new fuels. These studies are conducted
on versatile experimental combustion systems with the specific purpose of
developing combustion control technology for a specific fuel through single-
burner design criteria or other combustion modification techniques.
3.3.1 Improved Burner/System Design
The Institute of Gas Technology has submitted a report on the inves-
tigation of the relationship between combustion aerodynamics and air pollu-
tant emission characteristics of industrial gas burners firing natural gas.
Three types of burners were studied: a scaled-down utility boiler burner,
a kiln burner, and a baffle burner for steel reheat furnaces. The boiler
burner showed NO reductions up to 91 percent with FGR. For the boiler
/\
burner, use of a 30-degree ring nozzle consistently produced lower levels
of NO emissions than the 60-degree gun nozzle. For the kiln burner, NO
A X
emission reductions as high as 68 percent were demonstrated. The preferred
approach was to modify burner parameters to yield the flame shape and length
that will produce minimum NO emissions. For the baffle burner, external
A
flue gas recirculation of 30 percent resulted in as high as 90 percent reduc-
tion in NO emissions. Present emphasis in this study is on the assessment
A
of the emission characteristics of low Btu gases fired at ambient and ele-
vated temperatures. Five gases are being investigated representative of the
following industrial processes: Wellman Galusha-Air, Winkler-Air, Lurgi-
Oxygen, Winkler-Oxygen, and Koppers Totzek-Oxygen. The overall objective of
this program is to develop technology to allow optimum low-emission combustion
systems to be designed and widely used by industry.
3.3.2 Advanced Combustion Modification Techniques
Aerotherm Division of Acurex Corporation is conducting a 2-year IERL-
RTP funded pilot-scale furnace test program to develop advanced combustion
control techniques for NO reduction. The test furnace, with a capacity of
J\
24
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3,165,000 KJ/hr (3,000,000 Btu/hr) is being operated in the wall-fired and
tangential, corner-fired modes and is capable of firing coal, oil, gas,
mixed fuels, waste fuels, and synthetic fuels from coal. The furnace was
designed to give a temperature/time profile of the combustion gases repre-
sentative of industrial and utility boilers providing for more direct trans-
lation of low NO firing configurations to full scale equipment. The results
A
of this program will guide demonstration tests on large-scale prototype
units and provide suggestions for advanced equipment design. Preliminary
baseline, uncontrolled tests showed very good correspondence with full-
scale equipment with both the level of NO emission and the trend with
y\
excess air and preheat. Emphasis to date in the NO control development
A
tests has been on optimizing procedures for staging by use of overfire air
ports with the firing of pulverized coal in the wall-fired mode. Variables
considered in the optimization tests include first-stage stoichiometry and
mixing, first and second stage stoichiometry, overfire air preheat and in-
jection pattern, total excess air and burner air preheat. Tests with a high
nitrogen Kentucky bituminous coal have shown NO reductions in excess of 75
A
percent when the primary flame zone is operated with 90 percent or less of
stoichiometric air. At a total excess air level of 15 percent, NO emissions
A
are in the range of 100 to 200 ppm (corrected to zero percent 0?) with staged
combustion compared to a level of 850 ppm with normal, uncontrolled opera-
tion. These optimization tests are being extended to the firing of other
coal types and to operation in the tangential firing mode.
Rocketdyne Division of Rockwell International under IERL-RTP contract
has recently completed a two-part study which resulted in the development of
an advanced design residential warm air oil furnace which offers a 65 percent
reduction in NO emissions and up to 10 percent increase in fuel efficiency.
X
The initial effort involved the development of an optimal oil burner head
through evaluation of the effects on NO formation of combustion air, swirl
A
angle, nozzle spray angle, axial injector placement, flue gas recirculation,
and combustion gas recirculation as a function of oil flowrate and overall
excess air. The optimized burner was a nonretention gunburner with an optim-
ized choke-diameter and swirl vanes. Hydrocarbon and CO emissions remained
at commercial burner baseline levels while NO emissions were 1 g NO/kg fuel
A
25
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Multiburner experimental furnace (3 million Btu/hr)
26
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compared to 2 to 3 g NO/kg fuel at baseline. The second part of the program
was directed toward development of an optimized burner/firebox combination.
The final design utilized the optimized burner firing into the side of a
vertical, cylindrical, fin-cooled firebox. At 10 percent excess air, NO
A
emissions of 0.6 g NO/kg fuel were measured and increases in system effi-
ciency of up to 10 percent have been experienced. The system has recently
completed a 500-hour lab performance test and will be ready for field test-
ing in the near future. In addition to system development, the program has
evaluated techniques for mass production of the optimized head. A final
report is scheduled for completion in late 1976. A new contract has recently
been signed with Rocketdyne to extend the previous study to the investigation
of feasible manufacturing processes for the new oil furnace designs. This
contract calls for the manufacture of six units for use in field tests during
the 1977 to 1978 heating season.
A contract has recently been awarded to Honeywell for an experimental
study to investigate the characteristics of fuel oil atomization with a
thermal aerosol oil burner using #1 and #2 fuel oils with emphasis on combus-
tion efficiency, soot formation and design requirements. The effect of oil
temperature and pressure, droplet size, inlet air temperature, air/fuel ratio
and firing rate on flame luminosity, soot particle concentration and size
distribution, NO emissions and flue gas temperature will be investigated.
X
Additional measurements will be taken of CO, HC, smoke, 02, COp. stack
temperature and burner efficiency.
Ultrasysterns, Inc. is under contract to IERL-RTP to define low NO
A
burner design criteria for scale-up from an experimental 5 million Btu/hr
optimized burner to practical size burners (125 million Btu/hr). The scaling
criteria will assess the burner interactions occurring on full-scale boilers.
The emphasis is on coal burners, although residual oil and combined coal/low
Btu gas are also to be studied. The burner test facility was designed to
allow evaluation of the performance of single burners of capacity up to
125 million Btu/hr and multiple burners totaling 60 million Btu/hr in combus-
tion chambers simulating commercial practice. The facility has been completed,
and tests are scheduled for an early 1977 start date.
27
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ro
co
Full-scale burner test facility (125 million Btu/hr)
-------
Ultrasystems is also conducting a study to generate low emission bur-
ner concepts for residual oil combustion in packaged boilers. The study con-
sists of an experimental phase (for the development of burner design concepts
applicable to package boiler geometry) and an application phase (for testing
a prototype burner in a field operating boiler). To date, a variety of
burner configurations have been studied and an optimum has been identified
which gives NO reductions in the range of 65 to 75 percent for three fuel
A
oils with nitrogen content between 0.2 and 0.71 percent. The 0.2 percent
nitrogen produced the lowest NO (120 ppm) while maintaining acceptable
A
smoke levels. The results have also identified oil atomization conditions
and fuel properties as important variables governing both NO and smoke
levels. A contract is under negotiation to investigate these parameters as
related to combustion air flow patterns.
3.3.3 Catalytic Combustion
Aerotherm has recently been contracted by IERL-RTP to investigate the
concept of catalytic combustion in which premixed clean fuels are reacted
heterogeneously and at low temperature over catalytic monoliths. The overall
objective of the program is to provide scale-up criteria to allow application
to a wide range of stationary combustion equipment. The objective will be
met by screening small scale catalysts, performing small scale system concept
tests, and then scaling the results up to larger catalysts and systems.
Results of the small-scale catalyst screening experiments have identified
the graded-cell catalyst system as an acceptable concept for futher testing.
The graded-cell system uses a ceramic monolith with large cells at the com-
bustion inlet, with subsequent monolith sections having progressively smaller
cells. The catalyst used is platinum or an alumina washcoat. Tests with
this system have shown good performance under lean conditions with both
methane and propane fuels.
3.3.4 Alternate Fuels
Past in-house work has led to significant understanding of the forma-
tion and control of fuel NO produced from chemically-bound nitrogen. The
study has examined burner design, staged combustion, flue gas recirculation,
29
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and other techniques for control of both thermal and fuel NO from natural
gas, propane, distillate and residual oils, and coal. The current thrust of
this program is to define combustion and emission characteristics of alter-
nate fuels, with emphasis now being placed on high-nitrogen coal-derived
fuels. The program makes use of a versatile 300,000-Btu/hr experimental
furnace with provision for precise control of combustion parameters such as
fuel type and injection method, air rate and introduction method, air pre-
heat, firebox residence time, and firebox and convective section heat remov-
al rate. In addition, combustion modification techniques can be studied in
a variety of applications. The initial class evaluated was alcohol fuels,
which may be produced from coal gasification. They appear to have low
emissions of NO and favorable combustion characteristics relative to conven-
tional clean fossil fuels. The next class of fuels to be studied will be
low-Btu gas. A fuel gas generator has been designed and built by the Jet
Propulsion Laboratory under an interagency agreement and will be delivered
in late 1976. The key process variables will be CO/Hg/^ ratios, fuel gas
temperature, and NH., content.
3.4 FUNDAMENTAL STUDIES
lERL-RTP's fundamental research studies are providing an understand-
ing of the important phenomena in the formation and destruction of pollu-
tants during combustion. The basic knowledge is being translated to pilot
scale or field equipment studies to identify how the pollutant formation
mechanisms can be controlled through combustion process modifications. The
primary purpose of this program element is the application of fundamental
research to practical NO control problems with emphasis on interpretation
X
of test data, identification of further test programs, understanding and re-
solving operational problems, and suggestion of new research areas. A con-
tractor will soon be selected to perform and subcontract a highly coordi-
nated fundamental studies effort to consolidate the present programs. Pro-
gram efforts will focus on application to field and pilot scale test results.
Fundamental studies fall into two categories: combustion chemistry and com-
bustion aerodynamics. Combustion chemistry is a complex process involving
both fuel decomposition reactions and reactions of other flame species re-
30
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Experimental system for combustion modification and future fuel studies
-------
suiting in formation and destruction of pollutant species. The pollutant
species of interest are NO , CO, HC, POM, carbon particulate, fuel ash, and
A
SO . The emphasis in this program is on NO, although the formation and de-
A
struction of other oxides and reduced nitrogen species (e.g., HCN and NH3)
are also included.
3.4.1 Combustion Chemistry
The area of combustion chemistry can be further subdivided into two
areas: pollutant formation related to combustion conditions, and pollutant
formation related to fuel composition. These areas are reflected in the
characterization of NO formed by fixation of atmospheric nitrogen at high
X
temperature in the combustion process as thermal NO , and that formed from
/\
oxidation of nitrogen chemically bound in solid and liquid fossil fuels as
fuel NO . For most fuels the total NO is the composite formed by both
X A
mechanisms.
A new experimental program has recently been awarded to United Tech-
nology Research Center for investigation of nitrate and sulfate formation
and NO /SO interactions in flat flames in which various dopants will be
X X
used to promote formation of these species. Tests will be conducted to de-
termine the extent of in situ probe interference on NO measurements in
~~ ~~""~" ~~ X
flames. A variety of measurement techniques will be used in this determina-
tion including microprobes, and optical and molecular beam mass spectroscopy.
The data gained on inflame species concentrations will then be used to de-
termine respective formation mechanisms through use of the PROF computer
program described below.
A computer program has been developed at Aerotherm to analyze com-
bustion and pollutant chemistry in premixed flat flames. The Premixed One-
Dimensional Flame (PROF) code is a powerful tool being used to isolate
governing kinetics by comparison to experimental data from past and ongoing
flat flame measurements. PROF has the capability of handling multicomponent
diffusion, heat loss and wall effects characteristic of real flames. The
systematic comparison of data and suggested kinetics is revealing the govern-
ing mechanisms of pollutant formation and destruction including those of
inorganics and fuel nitrogen. Successful utilization of the PROF code will
demonstrate the strong coordination between the experimental and analytical
activities in fundamental studies.
32
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Rockwell International's Rocketdyne Division is working, under an
IERL-RTP contract, to establish the mechanism and chemistry of fuel nitrogen
conversion to NO and other products. An experimental and analytical study
A
has been carried out to investigate the chemical mechanisms involved in the
conversion of fuel nitrogen to NO in combustion as a means of developing
new approaches for minimizing fuel nitrogen conversion. The experimental
work was composed of two portions: (1) pyrolysis reactions that the vola-
tile fuel nitrogen compounds will undergo before approaching the flame front,
and (2) combustion reactions of fuel nitrogen compounds and their reaction
products. Pyrolysis experiments were conducted with model fuel nitrogen
components, to measure the kinetics parameters that determine under what con-
ditions typical fuel nitrogen structures will decompose and to identify the
nitrogen-containing species that are formed. Common fuel nitrogen structures
were represented by the model compounds pyridine, pyrole, quinilone, and ben-
zonitrile. Fuel oils and coals were subsequently pyrolyzed under similar
conditions, and the nitrogen containing inorganic products were measured and
compared with those formed by the model compounds. Results indicate that
HCN is a likely important intermediary compound in the formation of fuel NO
A
from fuel bound nitrogen in combustion. Burner studies of fuel NO reaction
A
paths induced by the addition of HCN and NH3 to premixed CH^-02-Ar flames
were also conducted to determine the kinetics of NO formation from these in-
termediaries. Results indicate that fuel NO forms relatively slowly above
the luminous zone in the same region where CO is oxidized to CO^ or after.
Results also indicate that NH- may yield HCN as an intermediary in the re-
action to form NO. High NO yields were found with lean flames and low NO
yields, with rich flames. A one-dimensional mathematical kinetic-diffusion
model for the combustion of oil droplets and coal particles was developed
to simulate the thermochemistry controlling the formation of fuel NO . The
A
model is being used in a continuing effort to define the mechanisms and
chemical paths leading to fuel NO . This contract has been extended to con-
/\
sider the pyrolysis of additional nitrogen containing fuels and pure com-
pounds under oxidation conditions and further to explore the interactions of
thermal and fuel NO formation mechanisms in flames.
A
MIT, under IERL-RTP sponsorship, is investigating the formation of
soot and polycyclic aromatic hydrocarbons (PCAH) in combustion systems.
33
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The objective of the study is the assessment of the production of particu-
late organic matter (soot and organic compounds) in well-defined yet relevant
combustion systems. Tests are being conducted on both laminar and turbulent
atmospheric diffusion flames. Acetylene-oxygen laminar flat flame tests
will be conducted at full equivalence ratios and burner exit velocities, and
data will be taken on species concentrations, temperature profiles, and par-
ticle concentration and size distribution as a function of position in the
flame. A water-cooled sampling probe will produce data on mass loadings of
soot, number concentration, and size distribution of soot and concentrations
of PCAH species in the turbulent diffusion flame. The apparatus is capable
of burning either liquid or gaseous fuels with variation of equivalence ratios
and full injection modes. Preliminary runs at an equivalence ratio of 1.0
showed a 4 order of magnitude increase in exhaust gas soot loading with a
decrease in atomizing air pressure from 20 to 10 psig. This illustrates the
extreme sensitivity of soot emissions and possibly PCAH emissions to changes
in combustor firing practices in an effort to reduce NO .
/\
Further grant studies by MIT on the fate of coal nitrogen during py-
rolysis and oxidation are now in progress. The overall objective of this
study is the determination of the distribution of fuel nitrogen between char
and volatiles and the fate of the char and volatiles under simulated com-
bustion conditions. Tests are conducted on a controlled atmosphere isothermal
furnace from which pyrolysis or oxidation products are withdrawn with a water-
cooled probe. Long residence times are simulated by allowing the coal par-
ticle to free fall through the furnace, and short residence times require a
high preheated gas flowrate. A swelling bituminous coal and a nonswelling
lignite of fuel nitrogen content 1.04 and 0.51 percent, respectively, have
been selected. Preliminary data indicate that: (1) fuel nitrogen devolati-
zation is kinetically controlled, (2) significant amounts of nitrogen (about
70 percent at 1750°K) may remain in the char after devolatization, (3) NO
formation decreases with increasing fuel/air equivalence ratios, and (4) as
much as 40 percent of the nitrogen may remain in the char at fuel/air equiv-
alence ratios greater than 1.5. From these findings, current data indicate
that nitrogen in the char may contribute significantly to NO emissions at
/\
temperatures below 1750°K but less at higher temperatures.
34
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Under an IERL-RTP grant, the University of Arizona is conducting an
experimental program to study the potential impact of fuel desulfurization
on the formation of NO emissions. Laboratory flat flame experiments showed
/\
that the presence of sulfur may inhibit the formation of thermal NO . Data
/\
were inconclusive in establishing a relationship between fuel sulfur and
fuel nitrogen conversion to NO . Further tests are presently being run on
/\
a larger furnace with swirling flames. These tests utilize dopants for both
nitrogen and sulfur compounds in oil flames.
3.4.2 Combustion Aerodynamjcs
Although combustion chemistry is responsible for the formation and
destruction of pollutants, the actual conditions that exist in the flame
zone are a strong function of the physical processes of combustion. Most
practical combustors operate with diffusion flames where the fuel and air
are introduced separately and mixing depends on the manner of introduction.
The flame zone is not of homogeneous composition; therefore, it is
necessary to understand the role of combustion aerodynamics in pollutant
formation.
United Technology Research Center is under contract to IERL-RTP to
investigate the interaction of aerodynamics and combustion chemistry (in an
idealized single burner combustor) as a function of fuel type and various
inlet parameters. During this study, detailed mapping of the local chemical
composition, temperature, velocity, and turbulence profiles is being accom-
plished. Initial studies, using in situ probes, investigated air preheat,
stoichiometry and flame swirl. Further testing utilizing a laser-doppler-
velocimeter (LDV) has recently been completed on gas and liquid fuel flames.
The LDV allows for the determination of turbulent flame structure without
probe interference, and it measures turbulence level as well as mean velocity.
Tests using the LDV on gas and liquid flames investigated the effect of swirl,
fuel/air velocities and pressure level on the flow and NO formation. Results
J\
showed that large scale turbulence was dominating both combustion and pollu-
tant formation. These results indicate a need to identify the interaction
of turbulence reaction kinetics within the flow field. Optical methods were
utilized to measure the liquid spray characteristics from the injection of
propane, iso-octane, and distillate oil. The results yielded good data on
35
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spray pattern, velocity profiles and droplet particle spacing. Reports on
the UTRC experimental studies are due out soon. The UTRC experimental pro-
gram is part of a coordinated experimental/analytical program to produce
tools with which to evaluate practical test results. The analytical portion
of the UTRC program is investigating the use of flow field computations to
describe recirculating combustion flow. In addition, UTRC has been working
to improve a computer code for rigorous solution of the Navier-Stokes flow
equations. The major effort has been on improving the turbulence model and
comparing model predictions with cold-flow and hot-flow furnace data. To
date, simple chemical kinetics have been used. The strong influences of
boundary conditions in general and of radial inlet profiles in particular on
predictions have been demonstrated. It appears that advances in numerical
differencing techniques will be needed before a generally applicable method
can be used to develop a simplified treatment of combustion chemistry and
aerodynamics.
3.4.3 Application for Combustion Control
A contractor is being selected to plan and execute a 3-year effort to
integrate the results of prior and ongoing fundamental studies and initiate
new studies of combustion and combustion generated air pollution. The new
program, scheduled for an early 1977 startup, will consolidate the diverse
fundamental studies projects into one large highly-coordinated program whose
efforts will be focused on application to field and pilot scale test results.
The control program has progressed to the stage where preferred approaches
to NO control have been well defined. Consequently, the fundamental studies
A
program is being structured to focus on needs in data interpretation, genera-
tion of new R&D directions, and operational problems.
36
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APPENDIX A
EPA/IERL-RTP REPORTS ON
NOY COMBUSTION MODIFICATION
A
37
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APPENDIX A
EPA/IERL-RTP REPORTS ON N0¥ COMBUSTION MODIFICATION
/\
The following reports funded by EPA/IERL-RTP or predecessor components
were published before December 1976:
EPA No.
APTIC 15568
APTIC 12619
APTD 1286
APTIC 28287
APTD 1268
AP 87
APTD 0924
NTIS No. (PB)
186-234
184-479
192-789
189-076
213-630
207-110
Report
"Fluid Bed Studies of the Limestone Based Flue
Gas Desulfurization Process", Esso (10/68).
"Systems Study of NOV Control Methods for Sta-
A
tionary Sources, Interim Report", Esso (5/69)
"Systems Study of NO Control Methods for Sta-
X
tionary Sources, Volume II, Final Report",
Esso (11/69).
"Models for NO Formation in Combustion Pro-
cesses", MIT (7/69-10/70).
"Reduction of Air Pollutants from Gas Burner
Flames Including Related Reaction Kinetics",
U.S. Bureau of Mines (1970).
"Residual Fuel Oil-Water Emulsions", Battelle
(1/70).
"Effects of Fuel Additives on Air Pollutant
Emissions from Distillate-Oil-Fired Furnaces",
EPA Control Systems Laboratory (IERL-RTP) (6/71)
"Systematic Study of Air Pollution from Inter-
mediate-size Fossil Fuel Combustion Equipment",
Walden Research (7/71).
38
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EPA No.
APTD 1163
EPA-650/
2-74-017
EPA-R2-72-
072a
APTD 1168
EPA-R2-73-
210
EPA-R2-73-
192
EPA-R2-73-
084a, b
EPA-R2-73-
291
EPA-R2-73-
292a
EPA-650/
2-73-018
EPA-650/
2-73-014
NTIS No. (PB)
210-739
230-095/AS
213-297
211-480
221-457
226-294
223-148
223-003
224-274/AS
223-002
Report
"Systematic Field Study of NO Emission Con-
trol Methods for Utility Boilers", Esso (12/71).
"Kinetic Mechanisms Governing the Fate of
Chemically Bound Sulfur and Nitrogen in Com-
bustion", Shell Development (8/72).
"State of the Art for Controlling NO Emissions,
A
Part 1: Utility Boilers", Catalytic, Inc.
(9/72).
"Laboratory Studies and Mathematical Modeling
of NO Formation in Combustion Processes",
Esso (1972).
"Stationary Internal Combustion Engines in
the U.S.", Shell Development (4/73).
"Systems Study of Conventional Combustion
Sources in the Iron and Steel Industry", Wal-
den Research (4/73).
"Field Investigation of Emissions from Com-
bustion Equipment for Space Heating", Bat-
telle (6/73).
"Nitric Oxides Formation in Combustion Pro-
cesses with Strong Recirculation", United
Aircraft (7/73).
"Experimental Combustor for Development of
Package Boiler Emission Control Techniques",
Ultrasystems (7/73).
"Catalytic Combustion, A Pollution-Free Means
of Energy Conversion?", EPA Control Systems
Laboratory (IERL-RTP) (8/73).
224-424/AS "Investigation of Surface Combustion Concepts
for NO Control in Utility Boilers and Sta-
/\
tionary Gas Turbines", Aerospace (8/73).
39
-------
EPA No.
EPA-650/
2-73-005
EPA-650/
2-73-029
EPA-650/
2-73-021
EPA-650/
2-73-031
NTIS No. (PB)
226-547/AS
EPA-650/
2-73-045
EPA-650/
2-74-003
EPA-650/
2-74-002a
EPA-650/
2-74-011
EPA-650/
2-74-023
EPA-650/
2-74-026
224-208
224-210/AS
225-037/1AS
230-008/AS
229-667/AS
229-986/AS
229-666/AS
232-287/AS
237-355/AS
"Program for Reduction of NO from Tangen-
rt
tial Coal-Fired Boilers", Combustion Engi-
neering (8/73).
"Interactions of Stack Gas Sulfur and Nitro-
gen Oxides on Dry Sorbents", EPA Control Sys-
tems Laboratory (IERL-RTP) (9/73).
"Proceedings, Coal Combustion Seminar, June
19-20, 1973", EPA Control Systems Laboratory
(IERL-RTP) (9/73).
"Effectiveness of Selective Fuel Additives
in Controlling Pollution Emissions from Resid-
ual Oil-Fired Boilers", EPA Control Systems
Laboratory (IERL-RTP) (10/73). - „
"Study of Combustor Flow Computations and
Comparison with Experiment", United Aircraft
(12/73).
"A Study of Air Pollutant Emissions from Resi-
dential Heating Systems", EPA Control Systems
Laboratory (IERL-RTP) (1/74).
"Effects of Design and Operating Variables on
NO from Coal Fired Furnaces, Phase I", Babcock
and Wilcox (1/74).
"Thermal Radiation Modeling for Pollution Pre-
dictions", Battelle (2/74).
"Flame Characterization Probes", Rockwell Int.
(3/74).
"Investigation of Particulate Emissions from
Oil-Fired Residential Heating Units", Battelle
(3/74).
40
-------
EPA No.
EPA-650/
2-74-026
EPA-650/
2-74-031a
EPA-650/
2-74-031b
EPA-650/
2-74-032
EPA-650/
2-74-038
EPA-R2-73-
292b
EPA-650/
2-74-066
EPA-650/
2-74-051
EPA-650/
2-74-78a
NTIS No. (PB)
237-355/AS
235-674/AS
235-675/AS
235-712/AS
233-037/AS
EPA-650/
2-74-045
EPA-650/
2-74-047
234-149/AS
236-647/AS
236-752/AS
Report
"Investigation of Participate Emissions from
Oil-Fired Residential Heating Units", Battelle
(3/74).
"Application of Holographic Methods to the
Measurement of Flames and Particulate, Vol-
ume I", TRW (4/74).
"Application of Holographic Methods to Mea-
surement of Flames and Particulate, Volume II",
TRW (4/74).
"Design Trends and Operating Problems in Com-
bustion Modification of Industrial Boilers",
Battelle (4/74).
"Combustion Control of Pollutants from Mul-
tiburner Coal-Fired Systems", U.S. Bureau of
Mines (5/74).
"Kinetic Mechanism of Methane/Air Combustion
with Pollutant Formation", Ultrasystems (6/74).
"Design of an Optimum Distillate Oil Burner
for Control of Pollutant Emissions", Rockwell
Int. (Rocketdyne) (6/74).
"Package Boiler Flame Modifications for Reduc-
ing Nitric Oxide Emissions, Phase II of III",
Ultrasystems (6/74).
237-344/AS "Field Testing: Application of Combustion
Modifications to Control NO Emissions from
Utility Boilers11, Exxon (6/74).
237-115/AS "Assessment of the Applicability of Automotive
Emission Control Technology to Stationary
Engines", Aerospace (7/74).
238-920/AS "Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions
from Industrial Boilers, Phase I", KVB Engi-
neering (10/74).
41
-------
EPA No.
EPA-650/
2-75-012
EPA-650/
2-75-002b
EPA-650/
2-74-023
EPA-650/
2-75-017
EPA-650/
2-75-046
EPA-650/
2-73-005a
EPA-600/
2-75-019
EPA-650/
,2-75-061a
EPA-650/
2-73-005b
NTIS No. (PB)
241-918/AS
Report
"Analysis of Test Data for NO Control in
A
Gas-and-Oil-Fired-Utility Boilers", Aero-
space (1/75).
241-283/AS "Effects of Design and Operating Variables
on NO from Coal-Fired Furnaces, Phase II",
/\
241-780/AS
241-821/AS
241-911/AS
245-162/AS
245-054/AS
245-344/AS
246-889/AS
EPA-600/
2-75-046
EPA-600/
2-75-075
246-750/AS
248-099/AS
Babcock and Wilcox (2/75).
"Evaluation of Prechamber Spark Ignition
Engine Concepts", Aerospace (2/75).
"Identification and Characterization of the
Use of Mixed Conventional and Waste Fuels",
M.W. Kellogg (2/75).
"Evaluation of Low Sulfur Western Coal Char-
acteristics, Utilization, and Combustion
Experience", Monsanto (5/75).
"Program for Reduction of NO from Tangential
A
Coal-Fired Boilers, Phase II", Combustion
Engineering (6/75).
"Estimating the Kinetics of Combustion, Includ-
ing Reactions Involving Oxides of Nitrogen and
Sulfur", Stanford Research Institute (8/75).
"Influence of Aerodynamic Phenomena on Pollu-
tant Formation in Combustion, Volume I", United
Technology Research Center (7/75).
"Program for Reduction of NO from Tangential
A
Coal-Fired Boilers, Phase Ila, NOV Control
A
Technology Application Study", Combustion Engi-
neering (8/75).
"NO Combustion Control Methods and Costs for
A
Stationary Sources", Aerotherm (9/75).
"Effect of Fuel Sulfur on NO Emissions from
A
Premixed Flames", University of Arizona (10/75).
42
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EPA No.
EPA-600/
2-75-069a
EPA-600/
2-76-003
EPA-600/
2-76-039
EPA-600/
2-76-038
EPA-600/
2-76-037
EPA-600
2-76-088
EPA-600/
2-76-086a
EPA-600/
2-76-098a
EPA-600/
2-76-152a
EPA-600/
2-76-152b
NTIS No. (PB)
248-292/AS
248-139/AS
250-373/AS
250-878/AS
252-195/AS
251-919/AS
253-500/AS
Report
"Guidelines for Residential Oil-Burner Adjust-
ments", GPO Stock No. 055-003-0085-8, Battelle
(10/75).
"Survey and Evaluation of Kinetic Data on
Reactions in Methane/Air Combustion", Exxon
(1/76).
"Chemistry of Fuel Nitrogen Conversion to
Nitrogen Oxides in Combustion", Rockwell Int.
(Rocketdyne) (2/76).
"Residential Oil Furnace System Optimization",
Rockwell Int. (Rocketdyne) (2/76).
"Catalytic Oxidation of Fuels for N0y Control
A
from Area Sources", Aerotherm (2/76).
"Guidelines for Burner Adjustments of Commer-
cial Oil-Fired Boilers", Battelle (3/76).
"Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions
from Industrial Boilers, Phase II", KVB Engi-
neering (4/76).
254-167/AS "Burner Design Criteria for Control of NO
A
from Natural Gas Combustion, Volume I", Insti-
tute of Gas Technology (4/76).
256-320/AS "Proceedings of the Stationary Source Combus-
tion Symposium, Volume I, Fundamental Research",
EPA/IERL-RTP (6/76).
256-321/AS "Proceedings of the Stationary Source Combustion
Symposium, Volume II, Fuels and Process Research
and Development", EPA/IERL-RTP (6/76).
43
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EPA No.
EPA-600/
2-76-152c
NTIS No. (PB)
257-146/AS
Report
"Proceedings of the Stationary Source Com-
bustion Symposium, Volume III, Field Testing
and Surveys", EPA/IERL-RTP (6/76).
44
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APPENDIX B
CONVERSION FACTORS
To Convert from:
tons
inch
pounds/hour
gallons/hour
horsepower (boiler)
Btu/hour
pounds/square inch
To
kilograms
meter
kilogram/second
meter /second
watts
watts
pascal
Multiply by:
9.07 x 102
2.54 x 10
-2
1.26 x 10
1.05 x 10
-4
9.81 x 10
-6
-3
2.93 x 10
6.89 x 10
-1
-3
45
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TECHNICAL REPORT DATA
(Please read faz&uctions on the reverse before completing)
1. REPORT NO.
EPA-600/7-77-077
3. RECIPIENTS ACCESSION NO.
4. TITLE ANDSUBTITLE
EPA's Stationary Source Combustion
Control Technology Program--FY 1976
5. REPORT DATE
July 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
NA
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Acurex Corporation/Aerotherm Division
485 Clyde Avenue
Mountain View, California 94042
10. PROGRAM ELEMENT NO.
E HE 62 4 A
11. CONTRACT/GRANT NO.
68-02-2160
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERFL)
Task Final: Fiscal Year 1976
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES J.ERL-RTP project officer for this report is Joshua S. Bowen, Mail
Drop 65, 919/541-2470.
16. ABSTRACT
The report summarizes the objectives, highlights, and accomplishments
of EPA's research and development program for characterization, assessment, and
control of the environmental impact of stationary combustion processes and energy
conversion technologies. The combustion control program emphasizes the development
and assessment of combustion modifications and control techniques which will have
practical and economical application for controlling multimedia pollutants from a wide
variety of combustion equipment categories. Although the major emphasis has been
directed to the control of nitrogen oxides, the effort also addresses the reduction of
other combustion-generated pollutants while maximizing system efficiency and energy
conservation. EPA's combustion control program utilizes the talents and experience
of a variety of contractors in combination with a limited number of inhouse projects.
The cooperation and input of the industrial and academic sector has been very
effective in achieving a high degree of credibility for the technical results. Major
benefits of the program include improvement of the environment, particularly of air
quality, and enhancement of the nation's energy posture, by providing greater
flexibility for the use of coal as a major energy source.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution, Nitrogen Oxides
Combustion, Combustion Chambers
Fuels , Assessments , Field Tests
Utilities, Boilers, Industrial Processes
Stationary Engines, Catalysis, Heating
Air Pollution Control
Stationary Sources
Combustion Modification
Environmental Assess-
ment
Catalytic Combustion
13B
21B
21D
21G
07B
14B
13A 13H
07D
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report/
Unclassified
21. NO. OF PAGES
50
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
46
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