United States
                                Environmental Protection
                                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
                                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

                                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

(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 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
  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
  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

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-

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
  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
  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-
  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

"NO, Emissions Characteristics of
Arch-Fired Furnaces," Tim W. Sonnich-
sen. KVB, Inc., and J. E. Cidianowicz,
  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
  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-
  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

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

(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
  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-
  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
  The boiler  selection  process is near
completion:  a single-wall-fired  unit  is

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

"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
  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  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

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
  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
   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
  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

Session V (b) (Volume V)
Fundamental Combustion

(Tom  W. Lester, EPA, Session

"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'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-

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
  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
  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
  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
  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-
"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-
  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

Session VII (Volume IV)
Small Industrial, Commercial,
and Residential Systems

(J. DavidMobley, EPA, Session

"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-
  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-

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

"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
  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

"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
  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
  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

"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-
  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
  •  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
  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
  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-

(Robert E. Hall, EPA, Session

"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

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
  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

"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

"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
  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-
  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
  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

   The model spreader stoker wa
designed and the fabrication drawing
prepared. Construction  should b
completed in late 1980.

"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
  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
                                          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




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