&EFK
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory , _
Research Triangle Park NC 27711 ' f Ix
Research and Development
EPA-600/S9-81-028 Sept. 1981
Project Summary
Proceedings of the Joint
Symposium on Stationary
Combustion NO* Control
J. Edward Cichanowicz
The Joint Symposium on Stationary
Combustion NO, Control was held
October 6-9, 1980, in Denver, CO.
The symposium was sponsored by the
Environmental Protection Agency
(EPA) and the Electric Power Research
Institute (EPRI). More than 50 speakers
presented papers on recent develop-
ments in NO, control technology.
Cochairmen of the symposium were
Robert E. Hall, EPA, and J. Edward
Cichanowicz, EPRI. Introductory
remarks were made by Dan V. Giovanni,
Program Manager for Air Quality
Control, Coal Combustion Systems
Division, EPRI. The welcoming address
was given by Roger L. Williams,
Regional Administrator, EPA Region
VIII. Stephen J. Gage, Assistant Ad-
ministrator for Research and Devel-
opment, EPA, was the keynote
speaker. This project summary includes
abstracts of the papers presented at
the symposium. They have been pub-
. lished in five volumes:
I. NO, Emission Issues and Invited
Papers
II. Utility Boiler NO, Control by Com-
bustion Modification
III. Utility Boiler NO, Control by Flue
Gas Treatment
IV. NO, Control and Environmental
Assessment of Industrial Process
Equipment. Engines, and Small
Stationary Sources
V. Fundamental Combustion Research
and Advanced Processes
For ordering purposes, the papers
are keyed to their respective volumes
according to session.
This Project Summary was devel-
oped by EPA's Industrial Environmen-
tal Research Laboratory, Research
Triangle Park, NC. to announce key
findings of the research projects that
are fully documented in a separate
proceedings of the same title (see
Proceedings ordering information at
back).
Session I (Volume I)
NOx Emissions Issues
(Michael J. Miller, EPRI.
Session Chairman)
"Regulatory Pressures for Increased
NO, Control," Ronald E. Wyzga. EPRI
With a few notable exceptions,
powerplants can satisfy present regula-
tions with existing NO, controls. How-
ever, proposed and likely NO, regula-
tions are likely to require more extensive
NO, controls of new, and in some cases,
existing powerplants.
The Clean Air Act Amendments of
1977 establish a legislative basis in
three areas which could impact NO,
control. A short-term N02 ambient
standard could be more restrictive for
powerplants than existing SO2 stan-
dards, although the short-term standard
will probably not affect relatively
isolated small powerplants. A PSD
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(Prevention of Significant Deterioration}
program could produce significant
constraints on powerplant size, siting,
and control technologies. For example,
a PSD increment program, similar to the
SOz increment program, would probably
be much more restrictive than the
current SOz short-term increments.
Finally, imminent regulations could be
more constraining than current PSD
increments for powerplants in the
vicinity of Class I visibility areas.
Two additional sets of regulations
could also impact NO* emissions limits.
Many believe that NOX contributes
significantly to an acid rain problem,
and there are efforts to limit emissions
to address this problem. Such efforts
are likely to require stricter control of
powerplant NO« emissions. Additonally,
increased limitations on NO* emissions
may be required in some areas to
achieve ozone compliance.
An added regulatory dimension is the
requirement that control technologies
not introduce new environmental risks.
An interpretation and the significance
of this requirement for NOX control
technologies are discussed.
"Development and Revision of Air
Quality Standards with Special Atten-
tion to the NOz Standard Review,"
Michael H. Jones, EPA
This paper describes the process for
review of National Ambient Air Quality
Standards. Special attention is given to
the issues facing the EPA in assessing
the need for and nature of possible
modifications to the NOz ambient air
quality standards. The legal requirements
for the Clean Air Act Amendments of
1977 are discussed as they apply to this
review and to the decision process in
making a standard choice. The paper
describes not only the importance of the
scientific basis for selecting a standard,
but also the role of the policymaker and
the judicial process. Criteria document
development, the scientific review
process, the preliminary staff decision
paper, and the public review process are
all described. Finally, the critical elements
in the upcoming N02 standard decision
are identified and discussed.
"Acid Rain Issues," Ralph A. Luken,
EPA
EPA is concerned about the effects of
acid rain because the acidity of precip-
itation falling in the U.S., Canada, and
Scandinavia has been increasing for the
past 20 years. An annual average
precipitation of pH of 4.0 to 4.5 is not
uncommon in the eastern U.S., south-
eastern Canada, and western Europe.
Acid rain has also become more
widespread in the past 20 years. Once
confined to urban and industrial areas,
the effects of acid rain are now being
experienced in places as remote from
industry as northern Minnesota and
Florida.
Although all the consequences of acid
deposition are not well understood, a
growing body of evidence suggests that
acid rain is responsible for substantial
adverse environmental effects. These
include the acidification anddemineral-
ization of soils; reduction of forest
productivity; damage to crops; and
deterioration of buildings and manmade
materials. In addition, the effects of acid
rain on metallic elements in soil, aquatic
ecosystems, and drinking water systems
may affect human health adversely.
Current EPA authority generally
focuses on control of the groundlevel
concentrations of the precursor pollu-
tants of acid rain. Control of these
concentrations will not necessarily
impact the level of acid rain which is
more a function of the total precursors
emitted into the air in a region over an
extended period of time.
To reduce SOz and NOX emissions,
EPA (in cooperation with the Depart-
ment of Energy) is evaluating alternative
emissions reductions strategies. These
strategies focus primarily on utility and
industrial boilers.
"State of California Perspective on
Stationary Source NOX Controls,"
Alan Goodley, California Air Resources
Board
The California NOX control program is
directed toward the achievement and
maintenance of air quality standards
not only for NOz, but also for ozone, total
suspended particulate, and visibility. In
addition to stringent controls on mobile
sources, controls on existing stationary
sources and best available control
technology (BACT) on new sources are
needed in nonattainment areas. In
these nonattainment areas, the state is
encouraging local districts to adopt
controls on refinery boilers and heaters,
industrial boilers, gas turbines, sta-
tionary internal combustion engines,
glass plants, and cement plants, in
addition to existing controls on power-
plants. The state considers selective
catalytic reduction (SCR) to be BACT for
most natural-gas- and oil-fired com-
bustion sources, and that SCR will be
BACT. for coal-fired powerplants. It is
also believed that combustion modifi-
cation techniques can be improved so
that SCR may be unnecessary on some
sources.
Session II (Volume II)
Manufacturers Update of
Commercially Available Com-
bustion Technology
(Joshua S. Bowen, EPA,
Session Chairman)
"Fossil Steam Generator NO* Control
Update," Joseph A. Barsin, Babcock
& Wilcox Company
Since the Second NOX Control Sem-
inar of 1978, much additional informa-
tion has been collected concerning
actual NOX emissions from fossil fuel
powerplants equipped with Babcock &
Wilcox Dual Register Burners/com-
partmented windboxes/f urnace systems
on a wide range of both bituminous and
subbituminous coals. These field results
from actual units firing coal, oil, and /or
gas have demonstrated NOX reductions
of up to 60 percent compared to no NO*
control. This presentation shares
Babcock & Wilcox's present controlled!
NOX emissions level experience and the*
present status of their advanced NO,
control system to meet the more
restrictive NOX emission levels expected
in the future.
"Current Developments in Low NO*
Firing Systems," Donald J. Frey,
Combustion Engineering, Inc., and
Tomozuchi Kawamura, Mitsubishi
Heavy Industries
The development of low NOX firing
systems for utility and industrial steam
generators is reported. Low NO* firing
systems for natural gas and oil were
developed for horizontal and tangential
firing. The oil and natural gas "PM"
firing system uses fuel-rich and fuel-
lean regions in combination with flue
gas recirculation to achieve low NO,
emissions; the former region is produced
by a diffusion of flame, the latter, by a
premixed flame. The pulverized coal
"SGR" and "LNCFS" tangential firing
systems achieve low NO, emissions by
delaying mixing of the main combustion
air with the fuel.
"Development and Field Operation ol
the Controlled Flow/Split-Flame
Burner." Joel Vatsky, Foster Wheeler
Energy Corporation
An advanced low NO. coal burner has
been installed in a 375-MW front-wall-
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fired steam generator. Unstaged NOX
levels below 0.4 Ib/million Btu are
being consistently obtained with burners
having a maximum liberation rate of
285 million Btu/hr. Prototype tests of
this burner, in a 50 million Btu/hr test
furnace, have resulted in unstaged NOX
emissions of 0.25 Ib/million Btu; when
staged using overt ire air ports, emissions
were reduced below 0.20 Ib/million
Btu.
This high capacity low NOX burner
permits new steam generators to be
equipped with the same number of
burners and the same type of burner
management system as were used prior
to the advent of emission regulations.
The Foster Wheeler low NOX system is
also available for retrofit to older steam
generators.
This availability is timely in that it
provides an option for utilities, which
must convert from oil to coal, to use a
modern combustion system. This can be
of particular importance to those units
designed to fire "future coal," based on
the boiler, firing system, and perform-
ance coal availability of the 1950's
and 1960's, but have instead been firing
oil. A further advantage may be provided
by the large NO* reductions attainable
since these may permit trade-offs with-
in EPA's "bubble concept." However,
the actual NO, levels attainable for older
units would be site-dependent.
"An Evaluation of NO« Emissions
from Coal-fired Steam Generators,"
John J. Marshall and R.A. Lisauskas
and Riley Stoker Corporation
The design evolution of the Riley coal-
fired Turbo Furnace and Directional
Flame Burner is reviewed. Burner aero-
dynamics are characterized and the
effectiveness of burner adjustments
and staged combustion in reducing NOX
emissions in this unique firing system
are discussed. Field test emissions data
are presented and analyzed with respect
to burner operating variables. A decrease
in NOX emissions is observed as mixing
of fuel and air in the near-burner zone is
delayed. Further development of direc-
tional flame and controlled mixing
burners for coal-firing applications is
also discussed.
Session III (Volume II)
NOX Emissions Characterization
of Full Scale Utility Powerplants
(David G. Lachapelle, EPA,
Session Chairman)
"Fireside Corrosion and NOX Emission
Tests on Coal-Fired Utility Boilers,"
Erwin H. Manny and P. S. Natanson,
Exxon Research and Engineering Com-
pany
This paper describes the status of an
EPA-sponsored field study of NOX emis-
sions from coal-fired utility boilers.
Previous reports discussed the effective-
ness of combustion modification tech-
niques to significantly reduce NOX
emissions. The simultaneous investiga-
tion of side effects (e.g., particulate
emissions, boiler slagging, boiler per-
formance) did not identify any significant
problems. However, one potential side
effect—fireside corrosion on the boiler
waterwalls—was only partially studied.
Fireside corrosion rates obtained via
probes (short-term exposure) could not
be correlated conclusively with actual
furnace tube wastage experience. There-
fore, a long-term corrosion test was
undertaken to obtain representative
furnace tube corrosion rate data. Results
of this test, conducted on the 500-MW
No. 7 pulverized-coal-fired boiler at the
Crist Station of the Gulf Power Company,
are presented and discussed. Details
and a progress update are also given for
ongoing corrosion investigations spon-
sored by EPA on four large coal-fired
utility boilers designed to meet NSPS
NOX emission standards. Information is
also included on a field test using
additives to suppress slag formation in a
330-MW pulverized-coal-fired utility
boiler.
"NO, Emissions Characteristics of
Arch-Fired Furnaces," Tim W. Sonnich-
sen. KVB, Inc., and J. E. Cidianowicz,
EPRI
Field tests have been conducted on
three subbituminous pulverized-coal
arch-fired utility boilers. The objective of
these tests was to determine "as-
found" NOx emission levels and the
influence of combustion modifications
on these emissions. These configurations
are unique in that the coal is introduced
downward from the arch into the furnace
with the bulk of the combustion air
added through the front wall perpen-
dicular to the flame jet. Staged combus-
tion conditions are thereby generated
which have been shown to be conducive
to low NOX emissions.
Corrected NOX levels ranged from 200
to 350 ppm. The lowest emissions were
emitted from the largest (275 MW)
boiler. Variations in excess air, air flow
injection distribution between burner
and front wall, burner stoichiometry,
and coal properties were shown to
impact NO emissions by 5 to 35 percent.
These results are discussed. Compari-
sons are made between these emissions
and the NOX levels from low NOX burner/
furnace designs to meet NSPS regulations.
"Combined-Cycle Powerplant
Emissions," P.L. Langsjoen, R.E.
Thompson, and Lawrence J. Muzio,
KVB, Inc., and M.W. McElroy, EPRI
The retrofit of existing utility steam
boilers with a combustion gas turbine to
supply hot vitiated combustion air to the
windbox of a fired boiler, in place of the
normal forced-draft fans and air pre-
heaters (i.e., repowering), can lead to
increased power output at improved
heat rates. A major consideration in
converting to combined-cycle operation
is the impact on the NOX emissions from
the system.
A field test program was conducted to
determine the NOX characteristics of a
220-MW supplementary-fired unit. A
primary objective was to determine the
fraction of the gas-turbine generated
NOX that can potentially be reduced
upon passage through the combustion
zone of the boiler. As part of this test
program, the boiler was operated in a
low-NOx staged-combustion configura-
tion by removing selected burners from
service.
Baseline NOX emissions from the
combined-cycle system were found to
be substantially lower than NO, emis-
sions from the boiler alone when
operated with ambient air supplied by
forced-draft fans: 1.4 Ib N02/MW-hr
compared to 2.3 Ib N02/MW-hr at boiler
loads of 190 and 200 MW, respectively.
In a staged Combustion configuration
with 4 of 20 burners removed from
service, the combined-cycle NOX emis-
sions were reduced to 0.9 Ib NO2/MW-
hr.
The fraction of gas-turbine-generated
NOx reduced upon passage through the
combustion zone of the boiler was
determined by doping the gas turbine
fuel with nitrogen (ammonia) to artifi-
cially vary the boiler inlet NO, levels
during combined-cycle operation. The
results showed that during normal
operation of the combined-cycle system
with all burners in service, 10 to 28
percent of the NO, produced by the gas
turbine was reduced (destroyed) in the
supplementary-fired boiler. During
operation of the boiler in a combustion
configuration, staged by removing four
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burners from service, a greater portion
of the gas-turbine-generated NO, was
reduced in the boiler.
"Relationship Between NOX and Fine
Particle Emissions," Michael W.
McElroy and R.C. Carr, EPRI
Data from EPRI -sponsored field test
programs at pulverized-coal-fired utility
plants indicate that boiler, combustion
conditions producing low NO* emissions
also tend to suppress the generation of
fine, submicron paniculate matter.
Specifically, the mass of fine particles
measured at the outlet of the boiler in
the 0.1 ym diameter region are reduced
by up to one or more orders of magnitude
when low NO, emissions are observed.
These observations are consistent with
the present theories of volatilization/
condensation processes believed to be
responsible for particle generation in
the particle size region.
The significance of this discovery is
that particulate collectors (electrostatic
precipitators and fabric filter baghouses)
generally exhibit a minima in collection
efficiency at this size region. Further-
more, these particles: (1) can contribute
to visibility problems due to particle
growth within the plume, and (2) have
been implicated as bad actors from a
health effects standpoint due to their
possible enrichment in trace elements
and unfavorable transport properties. It
now appears that these deficiencies
inherent to particulate control devices
may, in part, be overcome by the
application of NO, combustion controls.
Session IV (Volume II)
Low NOx Combustion
Development
(Michael W. McElroy, EPRI,
Session Chairman)
"Commercial Evaluation of a Low NO,
Combustion System as Applied to
Coal-Fired Utility Boilers," Stephen
A. Johnson and Todd M. Sommer,
Babcock & Wilcox Company
Development testing of an advanced,
two-stage combustion system, capable
of limiting NO, emissions from pulver-
ized-coal-fired boilers to less than 0.2
lbm NOz/108 Btu has been completed.
Test programs have been conducted on
both 1.2 MWT and 10.2-MWT systems.
These tests have confirmed that NOX
emissions can be correlated to a dimen-
sionless parameter proportional to the
second stage flame temperature. In
addition, scaleup criteria were formu-
lated allowing the design of commercial-
scale low-NO, combustion systems.
Subsequently, a detailed engineering
evaluation was performed on two
candidate applications of this techno-
logy. The objectives of that study were:
(1) to refine scaleup correlations and
design procedures; (2) to conceptually
design a steam generator incorporating
the two-stage combustion concept; (3)
to economically evaluate that design as
compared to a conventional, post-NSPS
steam generator design; and (4) to iden-
tify areas of commercial concern with the
new designs and to recommend further
research to address these concerns.
This paper summarizes the significant
results and conclusions from the test
programs and the engineering study.
The favored venturi furnace system is
expected to limit NOX emissions from
coal-fired boilers to less than 0.2 lbm
NOa/106 Btu, while increasing the
capital cost of the boilers by significantly
less than the projected cost of tail end
NO, removal systems to meet future
strict NO, emission standards.
"Pilot Scale Evaluation of a Low NO,
Tangential Firing Method," John T.
Kelly, R.A. Brown, J.B. Wightman,
R.L. Pam, and E.K. Chu, Acurex
Corporation
The EPA/Acurex 293-kW pilot-scale
facility was used to develop a low-NO,
pulverized-coal-fired tangential system.
Low NO, is achieved by directing the
fuel and less than 20 percent of the
secondary combustion air into the
center of the furnace with the remaining
secondary combustion air directed
parallel to the'furnace walls. The
separation of secondary combustion air
in this manner creates a fuel-rich zone
in the center of the furnace where NO,
production is minimized. This combus-
tion modification technique has lowered
NO, 65 percent relative to conventional
tangential firing. In addition, CO, UHC,
and unburned carbon emissions are
substantially unaffected by the modifi-
cation. Also, the modification places a
blanket of air on the furnace walls
which is beneficial from wall corrosion
and slagging points of view. Finally, the
modification shows a decrease in NO,
emissions as firebox gas temperature is
increased. This characteristic might be
beneficially applied in a large-scale
system to reduce furnace volume, and
thereby capital cost, for a given com-
bustion heat release.
Tests are now underway to further
optimize and characterize this low NO,
combustion modification technique.
"The Development of Distribution
Mixing Pulverized Coal Burners," Dee
P. Rees, J. Lee, A.R. Brienza. and M.P.
Heap, Energy and Environmental
Research Corporation
This paper summarizes work spon-
sored by EPA to develop a low-emission,
distributed-mixing burner for pulverized
coal. Data for single and multiple
configurations in research furnaces at
10, 50,-and 100 x 106 Btu/hr are
presented. NO, emissions down to 100
ppm (0 percent 02, dry) have been
obtained for bituminous coals under
acceptable burnout conditions by sub-
stoichiometric burner staging. These
data show that the optimum burner
zone stoichiometry is approximately 70
percent of theoretical air for all burners
tested to date.
"The Development of a Low NO,
Distributed Mixing Burners for Pul-
verized Coal Boilers," Blair A. Folsom,
L.P. Nelson, Energy and Environmen-
tal Research Corporation, and J.
Vatsky, Foster Wheeler Energy Cor-
poration
This paper describes the development
of a low NO, pulverized coal burner for
demonstration in two small pulverized-
coal-fired boilers by 1982. The Dis-
tributed Mixing Burner concept pro-
vides for controlled mixing of the coal
with the combustion air to minimize NO,
emissions while maintaining an overall
oxidizing environment in the furnace to
minimize slagging and corrosion. The
design of a prototype field-operable
burner is discussed, and test data are
presented in a research facility, sug-
gesting that NO, emissions less than 84
ng/J (0.2 lb/106 Btu) might be attainable
in the field.
"Field Evaluation of Low Emission
Coal Burner Technology on a Utility
Boiler," Edward J. Campobenedetto,
Babcock & Wilcox Company
A program is currently in progress to
demonstrate the NO, reduction potential
of EPA's distributed-mixing burner
applied to a utility boiler. The demon-
stration program will evaluate both
emissions attributed to this burner as
well as the effects of the burner retrofit
on overall boiler performance and
efficiency.
The boiler selection process is near
completion: a single-wall-fired unit is
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being reviewed by EPA prior to final
negotiations. Several opposed-fired
units are still under consideration,
pending final decisions by the utilities
as to their interest in participating in the
retrofit demonstration program.
"Operating Experience and Field Data
of a 700-MW Coal-Fired Utility Boiler
with Retrofit Low NOX Staged Mixing
Burners," K. Leikert and Sigfrid
Michelfelder, Steinmueller GmbH
Forthcoming new federal regulations
on emission control for stationary
combustion systems will clearly define
tolerable NO, emission levels in
Germany and thus replace the present
"best technical means" approach.
This fact initiated an R&D program for
the development of cost-effective low-
NOX combustion equipment for use in
pulverized-coal-fired boilers.
The program, financially assisted by
the Federal Ministry for Research and
Development (Bundesministerium fur
Forschung und Technologie, BMFT),
was divided into two parts.
First, a distributed-mixing burner
design concept adopted for an envisaged
50 percent NO* reduction was tested
and optimized in a pilot plant test
program with a 2.5-MW burner. The
burner design concept was based'on a
conventional circular burner with
additional tertiary air nozzles distributed
concentrically about the burner mouth.
Within this program, a 65 percent NOX
reduction was achieved with an opti-
mized configuration of the distributed
mixing—respectively staged mixing
burner (SM-burner)—without disad-
vantageous changes in combustion and
emission characteristics.
Following the successful pilot plant
tests, the combustion equipment of a
700-MW coal-fired powerplant was
changed to SM-burners. Both to ease
the retrofit and to safely allow the
execution of a measuring program, a
retrofit burner (a modified version of the
optimized pilot burner design) was used
for the boiler. The modification resulted
in a limitation of the safely operable
teritary air mass flows and, thus to a
certain extent, reduced the staging
capability of the large burner.
In spite of the narrow operational
limits, the envisaged goal of a 50
percent NO» reduction was met in the
boiler demonstration tests. Further-
more, a burner-load-dependent auto-
matic secondary/tertiary air flow control
system (developed to guarantee safe
burner operation at low NOX levels over
a wide turndown ratio) was operated
successfully.
"Japanese Technical Development
for Combustion NO* Control,"
Kunihiko Mouri and Y. Nakabayashi,
Electric Power Development
Company, Ltd.
The Electric power Development
Company, Ltd., has been conducting a
research and development program on
combustion NOX control for coal-fired
boilers in cooperation with Japanese
boiler manufacturers. The target emis-
sion levels are 100 ppm (at 6 percent Oz
and 1.8 percent fuel nitrogen) and have
not yet been achieved.
However, the results obtained through
this R&D program have been applied
step by step to existing or new coal-fired
powerplants, with NOX emissions of
existing plants reduced to 160-300 ppm
(O2 = 6 percent, N = 1.2 percent), from
uncontrolled levels of 400-500 ppm. As
for the new coal-fired units, EPDC is
constructing boilers of 250 ppm (target)
level (O2 = 6 percent, N = 1.7 percent) at
Matsushima Thermal Power Station
(2,500 MW units) and is to construct a
200 ppm (target) boiler at Takehara
Thermal Power Station, unit NO. 3 (700
MW).
At this moment, EPDC believes that
NO* emission levels will be 150 ppm (Oa
- 6 percent, N = 1.8 percent design base)
for new boilers in the near future.
This paper describes an outline of
EPDC R&D programs, results of com-
bustion modification such as low-NO.
burners, two-stage combustion gas
mixing, a report of actual operation after
combustion modification, and an outline
of NOX control countermeasures for
new boilers.
Session V (a) (Volume III)
Postcombustion IMOX Control
(George P. Green, Public
Service Company of
Colorado, Session Chairman)
"Empirical Evaluation of Selective
Catalytic Reduction as a NOX Control
Technique," J. Edward Cichanowicz
and D.V. Giovanni. EPRI
Selective Catalytic Reduction (SCR)
has been proposed as a technique for
control of NOX emissions to levels
significantly below those mandated by
NSPS for coal-fired utility steam gen-
erators. EPRI is conducting an empirical
assessment of the feasibilty and cost-
effectiveness of SCR, using a pilot scale
system at the EPRI Arapahoe Emission
Test Facility to simulate authentic coal-
fired utility operating conditions. The
program is a logical extension of earlier
EPRI work defining economic feasibility
of postcombustion control, and com-
plementary to other pilot scale studies
in the U.S. and Japan.
The test program was initiated in
September 1980 on a facility capable of
treating 5,000 scfm of coal-fired flue
gas, an equivalent of 2.5 MW of
electrical generating capacity. The
facility employs a regenerative air
heater in series with a catalytic reactor
to assess potential impacts on air heater
performance. The tests will focus on
four major issues important to the
evaluation of SCR technology: (1)
process performance as defined by the
NOX removal capabilities at conditions
representative of authentic utility
application; (2) process operating
demands including the need for moni-
toring and control systems, consumables
such as ammonia, energy (pressure
drop and auxiliary power), operating and
maintenance requirements to maintain
process performance, and catalyst
lifetime; (3) environmental impacts due
to emissions of residual ammonia, S03
and sulfates and biosulfates of ammonia;
and the potential effects on S02 and
paniculate control; and (4) systemwide
operating effects such as increased
operating and maintenance of down-
stream surfaces (particularly the air
heater), heat rate penalty, and limitations
in load-following.
Results are' presented for the initial
tasks dealing with the evaluation of
measurement techniques, and prelim-
inary data describing reactor and air
heater performance.
"Assessment of NOX Flue Gas Treat-
ment Technology," J. David Mobley,
EPA
EPA has maintained a program to
further the advancement of NOX control
by flue gas treatment technology since
the early 1970's. The program consists
of technology assessment studies in
conjunction with small scale experi-
mental projects. These activities have
shown that an 80 to 90 percent
reduction of NOX emissions by selective
catalytic reduction with ammonia has
been commercially demonstrated on
gas- and oil-fired sources in Japan, and
that such processes are ready for test
application on coal-fired sources. The
Japanese experience, combined with
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experimental projects in the U.S.,
should establish the technology as a
viable control technique for use in
tackling N0« environmental problems in
the U.S. However, some significant
technical concerns need to be addressed
in demonstration projects before wide-
spread application of the technology can
be recommended.
"Development of Flue Gas Treatment
in Japan," Y. Nakabayashi, H. Yugami,
and Kunihiko Mouri, Electric Power
Development Company, Ltd.
The Electric Power Development
Company, Ltd. (EPDC) has been con-
ducting a research and development
program on selective catalytic reduction
(SCR) systems through joint research
with manufacturers since 1975.
From the results of this R&D program,
EPDC has identified a strong commer-
cialization prospective for the Low Dust
SCR System (LOSS) for coal-fired
powerplants. At this moment, EPDC is
constructing the demonstration test
equipment at Takehara Thermal Power
Station, Unit No. 1 (250 MW coal-fired),
and plans to construct the first full scale
commercial SCR equipment at Takehara
Thermal Power Station, Unit No. 3 (700
MW coal-fired).
Additionally, the High Dust SCR
System (HDSS) also offers significant
commercialization prospective, with the
exception of establishing removal
technology for NH3 contained in the ash
collected by cold-side electrostatic
precipitators.
This paper is mainly directed to the
results of R&D programs executed by
EPDC concerning SCR and air preheater
problems, overall flue gas treatment
technology for coal-fired boilers, and an
outline of Takehara's SCR systems.
"Status of SCR Retrofit at Southern
California Edison Huntington Beach
Generating Station Unit 2," L.W.
Johnson, Cornelis L. Overduin, and
D.A.Fellows, Southern California
Edison Company
Utilities in the Southern California
South Coast Air Basin are subject to a
regulation (Rule 1135.1) requiring 90
percent NOX reduction. Rule 1135.1
consists of four basic compliance
options: the first two options require
two stages with an intermediate mile-
stone reduction and a demonstration
unit of a 90 percent NOX reduction
system.
This paper describes the Selective
Catalytic Reduction (SCR) 107.5-MW
demonstration facility that SCE plans to
install on half of the Huntington Beach
Unit 2, 215-MW boiler. The physical
size, operation and maintenance, and
controls for achieving 90 percent NOx
reduction through normal load vari-
ations, as well as the status of the
project, are discussed.
The system retrofit requirements are
discussed with specific reference to the
differences between the demonstration
unit and other larger units and the site
constraints for retrofit on the larger
units. The operational and maintenance
requirements for a systemwide retrofit
and potential problem areas are also
reviewed.
The paper presents cost estimates for
the Huntington Beach demonstration
facility as well as SCE's projection of
cost for adding SCR on the majority of its
oil-fired units in the South Coast Air
Basin. These costs include capital as
well as O&M. All costs are in 1981
dollars.
Session V (b) (Volume V)
Fundamental Combustion
Research
(Tom W. Lester, EPA, Session
Chairman)
"The Fundamental Combustion
Research Program," T.J.Tyson, C.J.
Kau, T.L. Corley, WM. Randall Seeker,
W.Clark, J. Kramlich, M.P. Heap, and
W.S.Lanier, Energy and Environmental
Research Corporation, and W.S.Lanier,
EPA
EPA's Fundamental Combustion
Research (FCR) Program's goals, man-
agement structure, and output are
discussed. The basic research in this
coordinated effort is conducted in
support of EPA's low NOX burner
development program. The most im-
mediate objectives are: (1) a determi-
nation of the chemical limits of NO,
production in order to determine the
lower bounds of fuel and thermal NOX;
and (2) a description of fuel NO*
formation in turbulent diffusion flames
with gaseous, liquid, or solid fuels. To
achieve these goals, FCR's subcontracts
are divided among studies in transport
processes in reacting flows, gas-phase
chemistry, and the physics and chem-
istry of two-phase reacting flows. Work
performed in these areas is split almost
evenly between the prime contractor
and subcontractors. Among the most
important results to date are the
characterization of pyrolysis products
from a number of coals, the determi-
nation of the influence of particle size on
the physical mode of devolatilization,
and the initial development of gas-
phase kinetic schemes to model higher
hydrocarbon pyrolysis and oxidation.
"Two-Phase Processes Involved in the
Control of Nitrogen Oxide Formation
in Fossil Fuel Flames," Adel F. Sarofim,
J.M. Beer, L.D.Timothy, S.P. Hanson,
A.Gupta, and J.M. Levy, Massachusetts
Institute of Technology
The conversion of fuel-nitrogen to
nitric oxide in flames depends on a
number of physical and chemical
'factors, three of which are discussed in
this paper: the rate of evolution of fuel
nitrogen by heavy fuel oils, the temper-
ature-time history of burning coal
particles, and the kinetics of the
reduction of NO by char.
The nitrogen evolution of a stream of
a 150 /urn fuel droplet injected into a
heated helium stream was measured
for a Raw Paraho Shale oil and an Indo-
Malaysian residual fuel oil. The nitrogen
evolution during vaporization of the
dispersed oil droplets is found to depart i
significantly from that obtained under'
equilibrium distillation. For a Paraho
shale oil, the rate of nitrogen evolution
under the rapid heating experienced by
the droplets is retarded relative to that
observed under equilibrium conditions.
By contrast, preferential vaporization of
the nitrogen was observed for an Indo-
Malaysian residual fuel oil. The temper-
ature-time history and burning times of
coal particles burning singly were
determined by two-color optical pyro-
metry to provide insights on the role of
volatile combustion on nitric oxide
formation. The burning times and
intensity traces showed that 100-^m
particles of a bituminous coal produced
a detached volatile flame that was not
evident during the combustion of
smaller 40-pm particles. The last part of
the paper summarizes data on the
kinetics of NO reduction by char, the
enhancement of the rate of reduction in
the presence of CO, and the inhibition of
the reduction reaction by H2O.
"Gas-Phase Processes Involved in the
Control of Nitrogen Oxide Formation
in Fossil Fuel Flames," J.M. Levy, MIT
Energy Laboratory
Optimization of a control strategy for
NO, emissions from fossil fuel com-
bustion requires an understanding of
the mechanistic chemistry of fuel-
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nitrogen conversion. Computational
capabilitites are demonstrated to be
quite accurate in the presence of simple
fuels, but break down somewhat in the
presence of hydrocarbons. A quasi-
global method for computing fuel-
nitrogen conversion in a higher hydro-
carbon environment is described, and
the current status of modeling bound
nitrogen profiles in a Ci/C2environment
is presented.
Session VI (Volume III)
Status of Flue Gas Treatment
for Coal-Fired Boilers
(Dan V. Giovanni, EPRI,
Session Chairman)
"Countermeasures for Problems in
NOX Removal Process for Coal-Fired
Boilers," H. Itoh and Yoshihiro Kajibata,
Kawasaki Heavy Industries, Ltd.
The construction of many coal-fired
powerplants is being planned as a result
of the recent petroleum shortage, and
so the need for a DeNO, process for
coal-firing is increasing. However, there
are many problems to be solved in the
practical application of the DeNOx
process for coal-fired boilers, because
high concentrations of dust particles
and SO, are contained in the flue gas.
The major problems are: (1) catalyst bed
pluggage and catalyst erosion by dust
particles; (2) the influence of unreacted
NH3 and SOs from the DeNOx reactor to
the downstream equipment; and (3)
deactivation of the catalyst by dust
particles and SO*.
KHI has been working to solve these
problems and to put the DeNOx process
into practical use for coal-fired boilers
with the cooperation of EPDC for many
years. They have developed superior
catalysts having several characteristics,
including long life, SOx-resisting prop-
erties, dust-resisting properties, and
low conversion of SO2 to SOa. Further,
they have solved these problems and
have developed the most economical
and stable DeNO, process.
This paper describes the problems
involved in the practical application of
the DeNOx process for coal-fired boilers
and the Countermeasures undertaken
in KHI's DeNOx process.
"Treating Flue Gas from Coal-Fired
Boilers for NOX Reduction with the
Shell Flue Gas Treating Process,"
Jack 8. Pohlenz, and A.O. Braun, UOP
Inc.
Copper as copper sulfate (CuSO<) is
one of the groups of metals which, at
tempertures of 350° to 450° C, effec-
tively catalyze the selective reduction of
NO, in flue gas to nitrogen and water
with ammonia (NH3). Conversions and
efficiency (ammonia utilization) are
high, resulting in low concentrations of
NH3 in the treated gas.
If flue gas containing both sulfur and
NO, and the reductanct ammonia is
processed over copper at 400 °C, the
copper is converted first to the oxide,
then to the sulfate, and NOX reduction
begins. As the conversion to copper
sulfate continues, the NOX content of
the treated gas decreases to a minimum
value and the SOX increases approaching
that at the reactor inlet.
Copper sulfate can be reduced with a
variety of fuels: H2, CO, CH4, etc., at
400°C, yielding a concentrated stream
of S02, along with water and elemental
copper.
Thus, the copper system provides the
technical base for flue gas treating
capable of SO* reduction, NO, reduction,
and the simultaneous reduction of both.
It offers the potential of a dry process,
without byproducts, and with modest
energy requirements.
Such a process, the Shell Flue Gas
Treating (SFGT) process, is the subject
of this presentation. Commercial appli-
cations have been in operation since
1973, processing flue gas from various
fuels (not including coal).
UOP has operated an SFGT pilot plant
for several years at Tampa Electric
Company's Big Bend Station near
Ruskin, FL. The pilot unit treats a
slipstream of flue gas from one of the
utility's coal-fired boilers. DeSOx-only,
simultaneous DeSO,/DeNO», and (most
recently) DeNO»-only operations have
been conducted. The current program is
sponsored by EPA. Results of this effort
are described.
"The Hitachi Zosen NO. Removal
Process Applied to Coal-Fired
Boilers," Richard S. Wiener, P.
Winkler, Chemico Air Pollution Con-
trol Corporation, and S. Tanaka,
Hitachi Zosen
Hitachi Zosen is a leading supplier of
flue gas treatment systems for the
removal of NOX. They have nine com-
mercial plants in operation. Early in
1978 Chemico Air Pollution Control
Corporation acquired the North American
license for the Hitachi Zosen technology,
a dry process with selective catalytic
reduction, using ammonia. Because
many sources of flue gas that require
NOX removal also contain a high level of
dust, Hitachi Zosen has expended
considerable effort in developing a
catalyst bed that can operate without
plugging even though the gas contains
particulates. Pilot plant tests using a
specially designed metallic catalyst
have been successfully operated on
very dirty gases from steel sinter
operations and coal-fired boilers. An
extensive pilot plant program has been
in operation for over 1 year at Georgia
Power Company's Plant Mitchell in
Albany, GA. This is an 0.5-MW equiva-
lent demonstration plant for coal-fired
denitrification sponsored by EPA. Hitachi
Zosen believes that this testing has
shown the effectiveness of the process
over extended operating periods and the
soundness of the control system and
basic design.
"Babcock-Hitachi NO, Removal
Process for Flue Gases from Coal-
Fired Boilers," T. Narita, Hiroshi
Kuroda, Y. Arikawa, Babcock-Hitachi,
and F. Nakajama, Hitachi Ltd.
At the symposium in 1978 a paper
was presented entitled, "Some Exper-
iences of NOX Removal in Pilot Plants
and Utility Boilers." That paper gave the
history of developments of Babcock-
Hitiachi NO, removal processes, catalyst
characteristics, and several operating
experiences. This paper introduces
some of the improvements and devel-
opments achieved since then.
As far as coal-fired applications are
concerned, two systems are required.
The first one is DeNOx with low dust
loading, where the DeNO, reactor is
downstream of the hot electrostatic
precipitator (ESP); the second is DeNOx
with high dust loading, where the
DeNOx reactor is upstream of the cold
ESP. Although the selection of an ESP
system should be determined mainly
from the standpoint of performance of
collecting fly ash through the boiler, the
DeNOx process is applicable in either
case.
As for the two commercial DeNOx
plants with low dust loading from coal-
fired boilers, the design and manu-
facture are already complete; they will
go into commercial operation in
November 19BO and July 1981, respec-
tively. Concerning the DeNOx with high
dust loading, this paper introduces the
results of abrasion and performance
tests, under dust concentration of 15 to
20 g/Nm3, which confirm the reliabilty
of the catalyst.
-------
Another important aspect of the
Selective Catalytic Reduction (SCR)
process is reducing the conversion of
SOa to S03 to minimize the influence on
the downstream* equipment. A catalyst
has been developed with the lowest
conversion rate less than 0.5 percent
without decreasing the NOX conversion
activity at the rated load.
"Test Summary of an Integrated Flue
Gas Treatment System Utilizing the
Selective Catalytic Reduction Process
for a Coal-Fired Boiler," IM. Aoki,
Ishikawajima-Harima Heavy Industries
Company, Ltd., and John S. Cvicker,
Foster Wheeler Energy Corporation
This research program was initiated
to determine if flue gases from a coal-
fired boiler can be effectively denitrified
by using the selective catalytic reduction
process in combination with desulfuri-
zation and dust control as an integrated
system.
An experimental system was designed
to handle between 1,000 and 2,000
NmVhr of flue gas and measure such
parameters as catalyst life, catalyst
plugging, catalyst abrasion rate due to
ash, air heater plugging, hot ESP, wet
ESP, and bag filter efficiencies, along
with the efficiency of a limestone
desulfurization system.
Test results show that this integrated
approach to flue gas cleanup is feasible
and may be incorporated into a full-
scale, coal-fired boiler flue gas design.
This testing will be continued to develop
a more reliable integrated flue gas
treatment system prior to commercial-
ization.
"The Development of a Catalytic NO,
Reduction System for Coal-Fired
Steam Generators," Tadamasa Sen-
goku, Y. Todo, N. Yokoyama, Mitsu-
bishi Heavy Industries, and Brooks M.
Howell, Combustion Engineering, Inc.
Work done recently by Mitsubishi
Heavy Industries in Japan has resulted
in the design and successful operation
of a full-scale catalytic NO* reduction
system for utility steam generators
firing coal.
This paper describes the design,
operation, and results of pilot-plant and
full-scale demonstration testing to eval-
uate the commercial feasibility of
catalytic- NO, removal from coal-fired
powerplant flue gases. In addition, the
design of a large, modern coal-fired
central station catalytic removal system
is presented.
Pilot testing of catalytic systems on
coal-firing was initiated attheTakasago
Station of EPDC in early 1977 using
plate type catalysts. In the third stage of
testing at Takasago (Fall 1979) the
program switched to testing grid type
catalysts. Since the conversion to grid
type support, more than 5,000 hours of
operation have been logged while
maintaining 90 percent NO, removal in
both a low and high dust load environ-
ment.
At the Nakoso Station of the Joban
Joint Power Company, a grid type
catalytic system has been operating for
over 6,000 hours with a removal
efficiency of 85 percent. Operating
under both high and low dust load
conditions, there as at Takasago, draft
losses have been maintained at low
levels with only limited soot blowing in
the low dust load case and no soot
blowing in the high dust load case.
At the Shimonoseki Station of the
Chugoku Electric Power Company (156
MW), in operation since April 1980, the
first full-scale coal-fired system in the
world has run smoothly since startup at
51 percent removal efficiency. The
design removal target value for this
system was 50 percent.
The paper also discusses ammonia
slip, gasflowrequirements, catalyst life,
and catalyst blinding from fly ash. The
design of a 500-MW commercial unit
based on the results of the test program
is explained and the various factors
affecting large commercial designs are
discussed.
Session VII (Volume IV)
Small Industrial, Commercial,
and Residential Systems
(J. DavidMobley, EPA, Session
Chairman)
"Evaluation of Emissions and Control
Technology for Industrial Stoker
Boilers," Robert D. Giammar, R.H.
Barnes, D.R. Hopper, P.R.Webb, and
A.E. Weller, Battelle-Columbus Lab-
oratories
This paper gives results of a three-
phase program to evaluate emissions
and control technology for industrial
stoker boilers. The paper focuses on the
third phase, Limestone/Coal Pellet
Development, but summarizes the first
two phases. Alternate Fuels Evaluation,
and Control Technology Evaluation.
Because S02 appears to be the most
troublesome emission to control for
stokers, a limestone/high-sulfur coal
pellet was developed and evaluated as
an S02 control technique. Initially, this
pellet with a Ca/S molar ratio of 7 was
successfully fired in an 8-MWth indus-
trial spreader-stoker boiler with S02
emissions reduced by 75 percent,
However, from economical and opera-
tional standpoints, the amount of
limestone required had to be reduced to
correspond to a Ca/S molar ratio of 3 to
4. Furthermore, the mechanical prop-
erties of this pellet were inadequate to
withstand the severe stresses of an
industrial fuel-handling system. Ac-
cordingly, an R&D effort was undertaken
to refine the pellet. A refined pellet, with
a Ca/S molar ratio of 3.5 with appro-
priate binders was produced that had
similar or improved physical character-
istics of raw coals. Additionally, eco-
nomic analysis indicates that this pellet
can be produced for approximately
$15/ton above the cost of the high-
sulfur coal. This refined pellet was fired
in a 200-kWth laboratory spreader-
stoker boiler achieving sulfur captures
as high as 70 percent. However, when
fired in the 8-MWth (25,000 Ib steam/hr)
stoker boiler, sulfur captures on the \
order of 50 percent were achieved.
"Control of Emissions from Resi-
dential Wood Combustion by Com-
bustion Modification," John M. Allen,
Battelle-Columbus Laboratories
This program was conducted to
identify promising methods of reducing
emissions of air pollutants from resi-
dential wood-burning stoves. The
overall study included a review of the
few ongoing and recently reported
studies related to emissions measure-
ments, causes, and characterization.
The most significant emissions are
the hydrocarbons and CO released by
wood pyrolysis and the CO formed by
combustion under locally starved air
conditions. The hydrocarbons are
especially important: they have been
shown to contain polycyclic species
suspected as being carcinogenic.
An experimental phase of the Battelle
program included stove operations in
the laboratory, designed to correlate
emissions with design and operating
characteristics of the stoves. The
burning properties of different types of
fuel wood have also been investigated.
The combustion tests in radiant stoves
have been designed to identify those
phenomena that contribute directly and
indirectly to the emissions. The following
emissions have been monitored con-
8
-------
tinuously: 02, CO2, CO, NO, SO2, and
total hydrocarbons. In a few tests, stack
gases have been batch-sampled to
determine particulate emissions, and
the concentration of polycyclic organic
species in both particulate and gaseous
emissions. Continuous weighing of the
stoves during operation has provided a
measurement of burning rate.
The average emission factors for CO
and total hydrocarbons varied by more
than a factor of 10 between different
burning modes and rates. Both emis-
sion factors vary inversely with burning
rate. At the higher burning rates, CO
constitutes a larger fraction of the
emissions of combustibles. The emission
factors also vary inversely with excess
air ratio as measured at the stove outlet,
although a large fraction of the total air
may bypass the active burning zone in
most stoves. True down-draft combus-
tion produces low emission factors
compared to other modes of burning,
especially with a preheated air supply.
NOx emissions increase with overall
excess air in all the naturally drafted
stoves, ranging between 1 and 10
Ib/ton fuel.
Combustion modification techniques
were found to affect emissions and
therefore are of interest for emission
controls. These include fuel modifi-
cations, thermal and flow modifications
in the stove design, and operator
techniques.
"Field Tests of Eleven Stoker Coal-
Fired Boilers for Emissions Control
and Improved Efficiency," P.L.
Langsjoen, KVB, Inc.
This stoker test program was awarded
to the American Boiler Manufacturers
Association (ABMA) in late 1977 as a
result of the national interest in coal
utilization. The objective of the program
is to improve specification data relating
to emissions and efficiency of coal-fired
stoker boilers. Such data are required by
both industry and government to in-
crease coal usage.
Eleven stoker boilers were tested
including six spreader stokers, one
vibragrate stoker, and four overfeed
traveling and chain grate units. The
emissions and efficiency of each unit
were measured under a variety of
operating conditions. This paper deals
with particulate loading, NO. concen-
tration, and.combustibles in the bottom
ash and fly ash. The effects of stoker
design, boiler loading, excess air,
overf ire air, and coal properties on these
three types of emissions are also
discussed.
Test results show that overfeed
stokers have lower particulate and NO*
emissions, and lower combustible heat
losses than do spreader stokers. Fly ash
reinjection is shown to substantially
increase particulate loading in some
cases. Overfire air is shown to have little
or no effect on N0« emissions, and fly
ash combustible content is a function of
particle size. These and other relation-
ships are discussed. More importantly,
an attempt is made to quantify these
relationships and provide a broad data
base from which government and indus-
try may draw to implement sound
decisions for the future of coal.
Field testing was completed in late
1979. Individual site reports are avail-
able. A final project report is scheduled
for completion in late 1980.
Session VIM (Volume IV)
Large Industrial Boilers
(J. DavidMobley, EPA, Session
Chairman)
"Combustion Modification for Coal-
Fired Stoker Boilers," Kenneth L.
Maloney, K.F. Maloney, and M.J.
Pfefferle, KVB, Inc.
Preliminary results are presented
from a program to develop and assess
advanced combustion modification con-
cepts for coal-fired stoker boilers. Tests
on a 100,000-lb/hr steam-spreader
stoker boiler showed that overfire air
reduces smoke emissions only when
injected in a zone extending a few feet
above the fuel bed. Improved overfire air
design can permit lower excess 02 firing
for NOx control, while maintaining
acceptable smoke and CO emissions.
Staged combustion was applied to a
laboratory underfeed stoker (approx-
imately 240,000 Btu/hr heat input) to
reduce NO, emissions.
"Thirty-Day Field Tests of Industrial
Combustion Modifications," Wallace
A. Carter, KVB, Inc.
This paper is based on field tests
sponsored by EPA to evaluate the long-
term effectiveness of combustion
modifications for reducing NO, emis-
sions from industrial boilers. Five 30-
day field tests have been conducted so
far. The combustion modifications
evaluated include low excess air on a
coal-fired spreader stoker, staged
combustion air on a residual-oil-fired
boiler and staged combustion on a
pulverized-coal-fired boiler, low excess
air and staged combustion air on a
spreader stoker, and a gas-fired low-
NOx burner. Reductions in NOX varied
from 15 percent with the pulverized-
coal-fired boiler to approximately 70
percent with the gas-fired Iow-N0x
burners. No serious operational or
reliability problems were encountered,
and most units demonstrated an increase
in boiler efficiency.
"Applicability of Thermal DeNOx to
Large Industrial Boilers," Boyd E.
Hurst and C.E. Schleckser, Jr., Exxon
Research and Engineering Company
Exxon Research and Engineering
Company has developed and success-
fully applied a process called Thermal
DeNOx for removing NOX from flue gas
in stationary combustion sources. This
noncatalytic process is based on a gas-
phase homogeneous reaction. The
technology involves injection of ammo-
nia (NH3) and hydrogen (H2) into hot flue
gas within a prescribed temperature
range.
Thermal DeNOx has been commer-
cially demonstrated in gas- and oil-fired
steam boilers, utility boilers, and
process furnaces. Successful tests have
also been conducted on a municipal
incinerator and an oil-field steam
generator. Tests on flue gas generated
by coal combustion have demonstrated
the applicability of the process to coal-
fired boilers.
Cost effectiveness of the process is
superior to other competing flue gas
treatment processes in most applica-
tions. Also, Thermal DeNOx is not as
capital intensive as competing processes
and can be applied with similar cost and
performance effectiveness for either
grass roots or retrofit applications.
Session IX (Volume IV)
Environmental Assessment
(Robert P. Hangebrauck. EPA,
Session Chairman)
"Conventional Combustion Environ-
mental Assessment Program," Wade
H. Ponder, EPA
EPA's Industrial Environmental Re-
search Laboratory at Research Triangle
Park, NC, has developed and imple-
mented a major program for assessing
the environmental, economic, and
energy impacts of multimedia pollutant
emissions from stationary residential,
commercial, institutional, industrial,
and utility combustion processes. The
-------
Conventional Combustion Environmen-
tal Assessment (CCEA) Program has
become a major source of data and
information for Agency use in developing
and modifying' standards and control
technologies.
This paper presents the. theme,
objectives, pollutants of concern, current
activities, and some representative data
from CCEA Program projects. Included
are data from: (1) a comparative assess-
ment of coal- and oil-firing in an
industrial boiler, (2) environmental
assessments of an 820-MW, FGD-
controlled, coal-fired utility boiler and a
342-MW oil-fired utility boiler, (3) a
170-site field study of combustion
sources, (4) dry bottom industrial boilers
firing pulverized coal, (5) residential coal
combustion, and (6) wood combustion
studies.
"Combustion Modification Environ-
mental Assessment," E. Brent
Higginbotham, C. Castaldini, R.M.
Evans, K.J. Lim, Howard B. Mason,
and L.R. Waterland, Acurex Corpora-
tion
The Combustion Modification Envi-
ronmental Assessment (CMEA) was
started in 1976 as part of the EPA's
Conventional Combustion Environmen-
tal Assessment Program. The primary
CMEA objectives are to:
• Identify potential multimedia envi-
ronmental hazards from stationary
combustion sources before and
after the use of combustion modifi-
cations to control NO* and other
combustion-related pollutants.
• Develop combustion modification
application guidelines document-
ing the economic, energy, opera-
tional, and environmental impacts
of meeting prescribed emission
levels.
• Identify the most cost-effective and
environmentally acceptable com-
bustion modification techniques to
achieve and maintain environ-
mental goals for N02.
To support these objectives, the
emphasis in the CMEA is on field tests
to quantify changes in emissions,
energy efficiency, and operation due to
the use of combustion modifications.
The field testing uses the EPA environ-
mental assessment Level 1 protocol
which includes sampling and analysis
for NO,, SOZ, S03, CO, CO2, 02, trace
metals, organics, and trace inorganic
species. During the first 3 years of the
CMEA, field tests were done on three
utility boilers, two industrial boilers, a
gas turbine, and a residential warm air
furnace. Each source was either modi-
fied in the field for low NOX operation or
was equipped with low NOX designs.
Test results showed no major increase
in emissions due to combustion modi-
fications. Changes in emissions other
than NOX were typically within the
accuracy of the experimental methods,
or within the range of changes due to
day-to-day variations in fuel compo-
sition or unit operation.
Changes in the severity to the
environment of total source effluents
were secondary to the improvement due
to NOX reduction. Energy efficiency was
generally unimpaired or improved
through the use of combustion modi-
fications. One exception was a water-
injection-equipped gas turbine for
which a 2 percent efficiency decrease
was observed.
The CMEA program was recently
renewed to extend the field tests to
additional sources, advanced combustion
modification controls, alternate fuels,
and nonsteady operation. The site
selection and field test status for the
extended tests are described.
"Utility Boiler Environmental As-
sessment—the EPRI Approach,"
Monta W. Zengerle, EPRI
EPRI's environmental assessment
program for air emissions includes
physical and chemical characterization,
ecological and human health research,
and an integrated analysis of costs,
benefits, and risks associated with
various generating technology and
emission control approaches. Physical
and chemical characterizations are
approached from regional and localized
aspects and include primary and sec-
ondary pollutants. Regional transport
research began with the Sulfate Re-
gional Experiment (SURE) in the north-
eastern U.S. and continues with visibility
and acid deposition research in the East
and West.
Localized plume distribution is being
studied on a site-specific basis beginning
with simple, and continuing with more
complex, terrain. Both efforts include
extensive field measurements designed
to evaluate or develop modeling tech-
niques for predicting utility contributions
to ground-level concentrations or
deposition.
Ecological research currently empha-
sizes the potential effects of acid
deposition and includes watershed,
aquatic, forest, crop, and grassland
research. Currently studies focus on
biogeochemical processes which in-
fluence resultant soil and water acidity
and nutrient balance.
Health effects research concentrates
on determining human health effects of
airborne utility emissions using animal
studies, human clinical studies, and
epidemiology.
The ultimate objective of these
research efforts is the evaluation of
relative risk'of generation mixes and
emission control strategies.
Session X (Volume IV)
Stationary Engines and Indus-
trial Process Combustion Sys-
tems
(Robert E. Hall, EPA, Session
Chairman)
"Characterization and Oxidation ol
Diesel Particulate," David A. Trayser,
L.J. Hillenbrand, M.J. Murphy, J.R.
Longanbach, and A. Levy, Battelle-
Columbus Laboratories
This study is being conducted for EPA
to evaluate emissions control on light-|
duty diesel vehicles by postcylinder
oxidation. The primary objective is to
determine the feasibility of thermal or
catalytic oxidation as a means of diesel
paniculate emissions control.
The program plan includesa review of
the state of technology, detailed chem-
ical and physical characterization of the
particulate from a light-duty diesel
engine, bench experiments to define the
ignition and oxidation properties of the
particulate, experiments with catalytic
ignition of particulates, and experi-
mental evaluation of concepts and
devices for particulate emission control
by oxidation in the exhaust of an engine.
The particulate characterization is
being carried out using an Oldsmobile
4.3-liter diesel engine coupled to a
dynamometer with direct and diluted
exhaust particulate sampling and
measurement. Bench experiments are
being conducted with various types ol
hot-tube reactors and instrumentation
The particulate characteristics being
measured include: mass concentration
soluble organic content; carbon, hydro-
gen, and ash; trace mineral content
surface area; size distribution; anc
volume concentration. Results to date
show that, as engine load is increased
mass concentration increases substan-
tially and soluble organic conten
decreases, both hydrogen content anc
10
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ash content vary between 0.5 and 2
percent, the surface area is approxi-
mately 100 mVg, and the mass median
particle diameter increases with load
increase and is in the range of 0.1 to 0.3
fjm.
Preliminary catalytic ignition results
indicate that the ignition temperature of
the particulate can be substantially
reduced (at least 150°C) by application
of small concentrations of metal salt
solutions. In addition, it has been found
that the catalytic action of the metal salt
is enhanced by admixing salts such as
sodium or ammonium chloride and
nitrate. Copper salts have been found to
work best of the materials studied to
date.
"Single-Cylinder Tests of Emission
Control Methods for Large-Bore Sta-
tionary Engines," Robert P. Wilson,
Jr., Arthur D. Little, Inc.
The research work presented was
undertaken to develop combustion
modifications that substantially reduce
NOX emissions of large-bore engines,
without significantly increasing fuel
consumption of carbonaceous emis-
sions. The scope of the project covers
NOX control technology for diesel and
spark ignition engines, bore sizes
ranging from 8 to 20 in, and both two-
and four-cycle charging methods. The
current status of the project permits
reporting the results of 40 percent of the
Phase III experimental tests. In Phases I
and II, a compendium of 40 emission
control methods was prepared, and an
evaluation procedure was used to
narrow the list to the 12 methods now
being tested in Phase III.
Cooper Energy Services used a 20 in
bore, 330-rpm, single-cylinder engine
to test the effect of unmixedness
(modified fuel gas injection) and con-
ventional "tuning" methods (timing,
equivalence ratio, spark location, gas
valve location, and piston shape). The
principal finding was that NO, emissions
are more sensitive to air/fuel ratio than
any other variable, giving a factor of five
reduction as the equivalence ratio was
leaned out from
-------
NO. 2 oil were conducted to determine
the effects on NOX emission and furnace
efficiency of water injection into the
flame zone, steam injection into the
flame zone, flue gas recirculation, and
lowered excess air. With natural gas
fuel, the largest NO* emission reduction
was obtained using flue gas recirculation
(88-percent reduction). With No. 2 fuel
oil, the largest reduction occurred using
steam injection (89 percent).
The costs of water injection, steam
injection, and flue gas recirculation
were evaluated. Steam injection was
found to be the most cost-effective
combustion modification technique for
three heater sizes firing either natural
gas or No. 2 oil.
Session XI (Volume V)
Advanced Processes
(G. Blair Martin, EPA, Session
Chairman)
"Low IMOx Combustors for High
Nitrogen Liquid Fuels," Glenn C.
England, M.P. Heap, D.W. Pershing,
J.H. Tomlinson, and T.L. Corley,
Energy and Environmental Research
Corporation
The results of bench scale experiments
in a 21-kW tunnel furnace show that,
under unstaged combustion conditions,
total and fuel NOX emissions from 26
petroleum and alternative liquid fuels
correlate well with fuel nitrogen content.
The optimization of staged combustion
parameters in the fuel-rich primary
zone was studied to provide direct
guidance for advanced low NOX burner
designs for evaluation in a 900-kW
pilot-scale combustor. Detailed in-
flame measurements were made in
addition to exhaust measurements to
quantify the influence of first-stage
stoichiometry and temperature on the
fate of fuel nitrogen species. Exhaust
NOX emissions were found to be directly
related to the amount of total fixed-
nitrogen species (TFN = NO + HCN + NH3)
leaving the first stage. Increasing the
temperature of the primary zone de-
creased TFN concentration, resulting in
lower exhaust NOX emission.
"Fate of Coal Nitrogen During Com-
bustion," S.L. Chen, M.P. Heap,
David W. Pershing, R.K. Nihart, and
D.P. Rees, Energy and Environmental
Research Corporation
Twenty-six coals covering all ranks
have been burned under a wide variety
of conditions to ascertain the impact of
coal properties on the fate of fuel
nitrogen. Three burner systems were
used to vary the rate of fuel/air mixing
and fuel NO was identified by using a
nitrogen-free oxidant. It was found that
fuel nitrogen content is not the only
property controlling fuel NO formation.
It appears that nitrogen volatility as well
as total nitrogen content is important,
particularly under well-mixed condi-
tions.
Detailed specie concentrations were
measured under fuel rich conditions
and it was found that:
• The partition of nitrogen between
NO, NH3, and HCN depended on
coal type.
• Total gas-phase nitrogen specie
(fuel-rich) correlated with exhaust
NO (fuel-lean).
• Reducing the temperature of the
first stage increased gas-phase
nitrogen specie concentrations,
but reduced fuel emissions.
• This work will help in the general-
ization of low NOX burner tech-
nology to a wide range of fuels.
"System Applications of Catalytic
Combustion," John P. Kesselring,
W.V. Krill, S.J. Anderson, and M.J.
Friedman, Acurex Corporation
The development of catalytic combus-
tion systems is continuing toward the
prototype demonstration phase. Improved
catalyst materials have shown higher
maximum throughput capability and
uniform axial temperature profiles.
Special auxiliary components required
for fuel injection, ignition, and catalyst
temperature measurement have been
developed and incorporated into system
concept designs. The three combustor
concepts developed to the system
integration phase include a small gas
turbine combustor, a watertube boiler
concept, and a firetube boiler burner.
The model gas-turbine combustor
shows continued promise for low NOX
emissions with gaseous and distillate
fuels. Greatest development difficulties
are associated with introduction of the
premixed fuel/air mixture and its
interaction with catalyst lightoff sys-
tems. An integrated system has been
developed, including a multiple nozzle,
atomizing injector, and an opposed-jet
lightoff burner. Testing of the concept is
nearing completion to show its transient
and steady-state capabilities.
The watertube boiler concept uses
direct radiative transfer to watertubes in
the combustion region. Structural
problems of the radiative zone are
currently being addressed, and final
integration of the concept will follow.
Thermal NO* emissions are typically
less than 2 ppm.
The firetube boiler burner also uses
radiative heat transfer from a fiber
matrix burner to the wall of the firetube.
The matrix burner operates at a surface
temperature below 1644 K at low
excess air levels to control the formation
of thermal NOX. Pad material screening
tests have been conducted, and a
mockup burner test is in preparation.
Continuing program work will focus on
prototype development of the watertube
and firetube boiler concepts.
"Fixed-Bed and Suspension Firing of
Coal," S.P. Purcell, D.M. Slaughter,
J.M. Munro, G.P. Starley, S.L. Manis,
and David W. Pershing, University of
Utah
This paper summarizes the progress
made during the second year of a grant
to study the formation of pollutant
species, particularly NOX and SOX iri
fixed-bed and suspension combustion
of coal. During this period, the suspen-
sion furnace was completed and pre-
liminary experiments conducted. The
results suggest that the large particles
are essentially unreacted when they
reach the stoker bed. The burning rate ol
the small particles increased with
increased local oxygen concentration
and increased heating rate.
The fixed-bed furnace was alsc
completed and initial results were
obtained. These data suggest that the
nitrogen volatiles evolve from the bee
early in the combustion process anc
form significant amounts of NOX. Stagec
combustion appears to be a potentially
effective means of controlling NO
emissions from a fixed-bed system
Increased clinkering was not observe*
under staged combustion conditions
however, this is a potential problem ir
the application of this technology t<
larger scale units. Both overall excess
air level and overfire-air height wen
studied: neither appeared to be of first
order importance at the condition
investigated.
The model spreader stoker wa
designed and the fabrication drawing
prepared. Construction should b
completed in late 1980.
12
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"Pressurized Bench Scale Testing of
Low NOX LBG Combustors," Wyman
D. Clark, B.A. Folsom, W.R. Seeker.
C.W. Courtney, and M.P. Heap,
Energy and Environmental Research
Corporation
The high efficiencies obtained in a
combined gas-turbine/steam-turbine
power cycle burning low-Btu gas (LBG)
make it a potentially attractive alternative
to the high sulfur emitting direct-coal-
fired steam cycle. In the gasification
process, much of the bound nitrogen in
coal is converted to ammonia in the
LBG. This ammonia is largely converted
to NOx in conventional combustors.This
paper examines the bench scale per-
formance of reactors previously demon-
strated to produce low NOX emissions in
laboratory scale experiments. Low Btu
gas was synthesized in a catalytic
reformer and fired in two primary
combustors: a diffusion flame and a
platinum/nickel oxide catalytic com-
bustor. Effects of scale, primary
stoichiometry, pressure, throughput,
and primary residence time were ex-
amined. Lowest NOX emissions were
produced in rich/lean combustion,
utilizing either the diffusion flame or the
catalyst in the fuel-rich primary stage.
"Control of NO« and Particulates
Emission from SRC-II Spray Flames,"
Janos M. Beer, M.T. Jacques, S.
Hanson, A.K. Gupta, Massachusetts
Institute of Technology, and W.
Rovesti, EPRI
Experiments were carried out with
SRC-II fuels in a laboratory-scale
laminar-flow-reactor and in the 4- by 4-
ft MIT Combustion Research Facility. In
the laminar-flow reactor, monosize
droplet arrays were pyrolyzed in an inert
atmosphere at variable temperatures
and the time-resolved evolution of the
fuel nitrogen was determined. This
information was needed for the devel-
opment of a NOX control strategy by
staged combustion. Parallel with the
laboratory studies, experiments were
carried out with SRC-II liquid fuel sprays
in unstaged and staged turbulent diffu-
sion flames in a thermal environment
similar to that in a utility boiler. The NOX
and particulates emission was deter-
mined in unstaged flames for the effects
of the rate of fuel/air mixing, air
preheat, and the quality of atomization.
The results show that low overall excess
air (in a long slowly mixing turbulent
flame with a low degree of swirl in the
air for flame stabilization) can reduce
the NOx emission level to about 250
ppm from the 550 ppm obtained for
high-intensity fast-mixing flames. A
significant further reduction of NO, can
be achieved with staged combustion by
physically separated stages. In these
latter experiments, a computer analysis
of the fuel nitrogen conversion was
used to guide the experiments carried
out using the MIT Combustion Research
Facility. The distributions of NO, and
particulates in the flames were deter-
mined for the effects of the'primary
stage fuel/air ratio, temperature, and
atomization quality. The mixing in both
the fuel-rich and -lean stages and the
heat extraction along the flame were
closely controlled in these experiments.
Results show that NO. (3 percent Oz)
levels below 100 ppm can be achieved
without excessive emission of particu-
lates. The experimental data show the
same general trends for NO, emission
as a function of fuel equivalence ratio as
that predicted by the computer model.
While the NO, and particulate levels
achieved in these studies are most
encouraging, it is the development of a
strategy of NO, and particulate emission
control that is the main objective of the
present study. The emission levels
achieved in this study can be considered
as lower bounds for conditions in which
the mixing in the flame is controlled
more closely than can be achieved in'
practical utility boiler combustion
chambers.
J. Edward Cichano wicz is the project officer for the cosponsor, the Electric Power
Research Institute, 3412 Hillview Avenue, Palo Alto, CA 94303.
Robert E. Hall is the EPA Project Officer (see below).
The complete report, entitled "Proceedings of the Joint Symposium on Station-
ary Combustion NO* Control," is in five volumes:
Volume I. (Order No. PB 81-236 119; Cost: $9.50)
Volume II. (Order No. PB 81-236 127; Cost: $36.50)
Volume III. (Order No. PB 81-236 135; Cost: $21 50)
Volume IV. (Order No. PB 81-236 143; Cost: $30.50)
Volume V. (Order No. PB 81-236 150; Cost: $23.00)
Volumes I thru V. (Order No. PB 81-236 101; Cost: $110.50)
The above reports will be available only from: (prices subject to change)
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
US GOVERNMENT PRINTING OFFICE, 1981 — 757-012/7333
13
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