United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S9-86/021 Nov. 1986
v>EPA Project Summary
Proceedings: 1985 Joint
Symposium on Stationary
RECEIVED combustion NCL Control
NOV251986
ENVIRONMENTAL PROTECTION A6ENCS. Peralo
LIBRARY, REGION V
Together, the more than 60 presenta-
tions from this international gathering
constitute a comprehensive source of
information on nitrogen oxide (NOX)
emissions control technologies. As
such, they make a unique contribution
toward the development of cost-
effective and reliable control systems
for fossil-fuel-fired power plants.
This Project Summary was devel-
oped by EPA's Air and Energy Engineer-
ing Research Laboratory, Research Tri-
angle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report or-
dering information at back).
Introduction
The 1985 Joint Symposium on Sta-
tionary Combustion NOX Control was
held May 6-9 in Boston, MA. This was
the third symposium on NOX control
jointly sponsored by EPA and EPRI: the
first was in Denver in 1980; and the sec-
ond, in Dallas in 1982. The symposium
is a consolidation of EPRI's previous
NOX Control Technology Seminars and
EPA's Symposia on Stationary Source
Combustion. The objective of the sym-
posium is to give attendees the oppor-
tunity to exchange information on the
latest advances in combustion technol-
ogy and flue gas treatment processes
for stationary sources. Such an ex-
change of information contributes sig-
nificantly to the development of cost-
effective and reliable NOX emission
control systems.
Over 60 papers were presented dur-
ing the 4-day meeting which was at-
tended by representatives of 13 nations.
Topics ranged from full-scale applica-
tions of combustion modifications and
flue gas treatment to fundamental com-
bustion research. The speakers repre-
sented a variety of international organi-
zations including electric utility
companies, boiler and other related
equipment manufacturers, research
and development groups, and regula-
tory agencies.
Cochairmen of the symposium were
David Eskinazi of EPRI and Michael C.
Osborne of EPA. The keynote address
was delivered by Robert C. Carr, Depart-
ment Director of Environmental Control
Systems of EPRI's Coal Combustion
Systems Division and EPA's Carl R.
Gerber, Director of the Office of Envi-
ronmental Engineering and Technol-
ogy, Office of Research and Develop-
ment. The welcoming address was
given by C. Bruce Damrell, Vice Presi-
dent, Engineering and Distribution of
Boston Edison Company. The sympo-
sium proceedings are in two volumes:
• Volume 1: Utility Boiler Applica-
tions
—Session 1: Introduction
—Session 2: Manufacturer's Up-
date of Commer-
cially Available
Technology
—Session 3: Low-N0x Combus-
tion Development
—Session 4: Development and
Application of Fuel
Staging (Reburning)
—Session 5: Full-Scale Boiler
Application
—Session 7: Advanced Power
Plants
—Session 8a: Flue Gas Treatment
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Volume 2: Industrial Processes,
Fundamental Studies,
and Slagging Combus-
tors
6a: Externally Staged
Combustors (Slag-
ging Combustors)
Fundamental Com-
bustion Studies
Stationary Engines
and Industrial Proc-
ess Systems
Overview of Fur-
nace Sorbent Injec-
tion S02 Control
Fuel and Combus-
tion Modifications
for Commercial/In-
dustrial Boilers
6b
8b
9a
9b
—Session
—Session
—Session
—Session
—Session
Session 1
Introduction
(Michael C. Osborne,
EPA/AEERL, Session Chairman)
1-1. "An Overview of
International NOX Control
Regulations," Peter W.
Dacey, IEA Coal Research
The pace of development of NOX
emission control regulations has in-
creased rapidly in the past 2 years. This
paper looks at some of the factors
underlying this acceleration and the
regulatory development in different
countries. The experience in the Federal
Republic of Germany, Japan, and the
United States has been influential in de-
termining the timing and the form of
regulations in other countries. Within a
national framework, local agencies can
significantly affect the stringency of reg-
ulations at individual sites.
Using conversion factors for the dif-
ferent sets of units used allows inter-
country comparisons to be made. In
general the variation between countries
in their treatment of emission from dif-
ferent fuels is less significant than the
absolute differences between emission
levels for a given fuel. Treatment of par-
ticular plant sizes is generally in line
with the overall stringency of a coun-
try's regulations. Potential future devel-
opments are reviewed.
1-2. "Legal Instruments and
the State of Technology
for Reducing NOX
Emissions in the Federal
Republic of Germany,"
Helmut Keinhorst, Federal
Environmental Agency
The air pollution situation of the
highly polluted Federal Republic of Ger-
many was presented. In this context, the
considerable damage to buildings and
materials was considered as well as the
extent of recent forest damage. The le-
gal basis for the Programme of the Fed-
eral Government to reduce NOX pollu-
tion was explained. In particular the
Ordinance on Large Furnaces and the
Technical Instructions on Air Pollution
Control (Tl Air) were mentioned. The
measures being taken for the limitation
of NOX in Europe were dealt with briefly.
The primary measures under consid-
eration for the achievement of the re-
duction target and NOX flue gas treat-
ment technologies were presented.
Using plants being planned or under
construction as an example, it was
shown which rate of reduction can be
expected from the individual primary
and secondary measures. In conclusion,
a prognosis was made for the attainable
reduction potential through the intro-
duced measures. The result is that a
considerable decline in the pollution of
the environment may be counted on.
1-3. "Utility Perspective on
Low NOX Control,"
Dominick J. Mormile,
Consolidated Edison
Company of New York,
Inc.
The Empire State Electric Energy Re-
search Corporation has initiated a pro-
gram to provide the New York Power
Pool member utilities with information
to assess the impacts of implementing
alternative NOX controls on their boil-
ers. This paper discusses the need,
basis, and approach for conducting this
program.
1-4. "Role of NOX Emissions in
Acid Rain," Julius Chang,
National Center for
Atmospheric Research
This paper was not submitted for pub-
lication.
1-5. "Boreal Montane
Ecosystem Decline in
Central Europe and the
Eastern United States:
Potential Role of
Anthropogenic Pollution
with Emphasis on
Nitrogen Compounds,"
Robert I. Bruck, North
Carolina State University
A large scale decline of forests in the
Federal Republic of Germany involving
many tree species has been observed
and extensively studied since 1979. A
more limited decline of high altitude
boreal montane ecosystems (spruce-fir)
in the eastern United States has been in
progress for perhaps 20 years. The
unique nature of the observed symp-
toms, the location of the affected forests
in areas of high anthropogenic pollution
deposition, and the synchronized ap-
pearance of symptoms make it plausi-
ble that airborne pollutants coupled
with secondary natural factors are re-
sponsible for the forest decline. Of re-
cent interest is the possible role of nitro-
gen compounds in the forest decline
syndrome. Nitrogen (unlike sulfur) com-
pounds are highly active in forest
ecosystems. Foliar or root "fertilization"
of high altitude trees exposed to often
violent climatic conditions could and
probably do have numerous detrimen-
tal effects. These effects include reduc-
tion of frost hardiness, cell wall thin-
ning, and radical shifts in rhizosphere
and rhizoplane microorganism popula
tions. This could result in a "stress syn
drome" predisposing the affectec
ecosystems to secondary pathogens
and climatic factors.
Session 2
Manufacturer's Update of
Commercially Available
Technology
2-1. "Utility Steam Generator
NOX Control Update -
1985," P. L. Cioffi,
A. D. Larue, M. A. Acree,
Babcock & Wilcox
Babcock & Wilcox continues to ex
pand its NOX control experience am
technology along several fronts. Th<
Dual Register Burner/Compartmentei
Windbox system is successfully pei
forming on 35,200 MW of capacity in
wide range of coal boiler applications
In addition, there are several new low
NOX systems described in this pape
The Enhanced-lgnition Dual-Registe
Burner and the Hitachi-NR burners off€
improvements for difficult-to-bum fuel
and for further NOX reduction, respei
lively. In-furnace NOX reduction utilize
reburning technology to achieve e)
tremely low-NOx emissions for gas, oi
or PC and can be applied in new c
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retrofit situations. Also, the Low NOX
Cell is being developed for direct retrofit
for the unique cell burner design. Circu-
lating fluidized beds with low-NOx emis-
sions are being sold for a variety of ap-
plications. Finally, Furnace Sorbent
Injection combined with Iow-N0x burn-
ers is providing a means of simulta-
neous NOX/SO2 reduction for PC units.
2-2. "1985 Update of NOX
Emission Control
Technology at Combustion
Engineering,"
R. J. Collette, Combustion
Engineering, Inc.
Much discussion has transpired in the
past several years relating to the design
and development of technology associ-
ated with the control of nitrogen oxides
(NOX) from utility and industrial steam
generators. As a major supplier of
steam generators and fuel burning
equipment for the utility and industrial
marketplace. Combustion Engineering
is now in a position to report the results
of actual field operating data generated
in the past 2-1/2 years.
The NOX control techniques pre-
sented in this discussion are systems
which Combustion Engineering has de-
veloped internally or is licensed to build
by Mitsubishi Heavy Industries, Ltd.
(MHI) of Japan. This paper focuses pri-
marily on design application and recent
experience with NOX reduction tech-
niques referred to as the PM Burner
and, initially, the Low-N0x Concentric
Firing System.
2-3. "Current Development in
Low-NOx Combustion
Systems," R. A. Lisauskas,
C. E. McHale, Riley Stoker
Corp.
The current status of Iow-N0x com-
bustion controls for wall- and turbo-
fired furnaces is discussed. Pilot-scale
combustion tests have been conducted
on burner systems for both furnace con-
figurations. Second generation com-
bustion controls have been installed on
two new industrial-size front-wall and
Turbo-fired boilers. An advanced Turbo
furnace control system has been devel-
oped which integrates Iow-N0x burners
with air staging at multiple levels within
the furnace. Preliminary field test re-
sults have demonstrated that NOX levels
significantly below currently required
emission limits can be achieved with
this control system.
Advanced in-furnace NOX and S02
control techniques will require well
placed furnace overfire air, fuel, and
sorbent injection systems which
achieve good penetration and rapid
mixing.
An analytical flow simulation code is
being used to help establish design
criteria necessary to achieve effective
upper furnace overfire air, fuel, and sor-
bent injection systems which achieve
good penetration and rapid mixing. An
analytical flow simulation code is being
used to help establish design criteria
necessary to achieve effective upper
furnace mixing.
2-4. "Industrial and Utility
Boiler IMOX Control,"
E. S. Schindler, J. Vatsky,
Foster Wheeler Energy
Corp.
This paper summarizes Foster
Wheeler's commercial Flow/Split-Flame
Low NOX Coal Burner and field results.
Highlighted are up to 60% reduction in
NOX without changing the flame enve-
lope or increasing unburned carbon
loss; this combination makes the CF/SF
burner highly suitable for new and
retrofit situations. Field results for new
and retrofit burners are presented. Fu-
ture low-NOx burner concepts which
have the potential to further decrease
NOX emissions are discussed.
A summary is presented of Foster
Wheeler's SOz reduction work using
limestone injection into the furnace.
Prototype developments of this technol-
ogy along with field tests on an indus-
trial steam boiler are presented.
Finally, Foster Wheeler's large scale
combustion and environmental test fa-
cility, rated at a maximum of 75 x 106
Btu/hr heat input, is described.
Session 3
Low-NOx Combustion
Development
(Michael McElroy, EPRI,
Session Chairman)
3-1. "Experimental
Investigation of Retrofit
Low-NOx Combustion
Systems," R. Lisauskas,
R. J. Snodgrass, Riley
Stoker Corp.;
S. A. Johnson, Physical
Sciences, Inc.; D. Eskinazi,
EPRI
Pilot-scale development tests have
been conducted on advanced retrofit
Iow-N0x combustion controls. The tests
were conducted in a 100 x 106 Btu/hr
test furnace designed to simulate the
combustion environment in utility coal-
fired boilers. Several control options
were integrated by combining a low-
NOx burner with air and fuel combus-
tion staging within the furnace. Each
combustion modification technique
was evaluated over a range of design
and operating parameters. NOX reduc-
tions from 50 to 75% were achieved
with both advanced air- and fuel-staged
combustion. Test results are presented
along with a discussion of design con-
straints affecting the retrofit of combus-
tion control systems to existing utility
wall-fired boilers.
3-2. "Low-NOx Coal-Firing
System Demonstration
Results on a Tangentially
Fired Boiler," A. Kokkinos,
R. D. Lewis, Combustion
Engineering;
D. G. Lachapelle,
EPA/AEERL
The Low-NOx Concentric Firing Sys-
tem (LNCFS) was installed at Utah
Power and Light's Hunter No. 2 station
for demonstration purposes. The
LNCFS was installed at the 420 MWe
station during September 1981, for the
purpose of examining its NOX emission
reduction characteristics and its effects
on long-term boiler operation under
low-NOx firing conditions. The paper
presents the results of this long-term
study.
The data analysis shows that NOX
emissions can be reduced from base-
line emission levels to 460 (corrected to
3% 02) and 360 ppm without and with
overfire air, respectively, to levels of 240
to 260 ppm following the modification.
Long-term testing showed no effect of
the LNCFS on boiler operating parame-
ters. Thirty-day continuous NOX moni-
toring tests were also carried out aver-
aging 0.41 lb/106 Btu fired.
3-3. "Air Flow Modeling of a
750 MW Gas- and Oil-Fired
Boiler," D. P. Teixeira,
Pacific Gas and Electric
Co.; G. B. Gilbert,
Dynatech R/D Co.
Flow modeling of the air supply sys-
tem of Pacific Gas and Electric's Moss
Landing Boiler 6-1 was performed. The
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purpose of these tests was to improve
the performance and NOX emission
characteristics of the fuel-oil/natural-
gas fired unit. Objectives of the model-
ing were to achieve reduced overall ex-
cess air and flue gas recirculation (FGR)
levels by providing uniform air and FGR
flows to each of 48 circular cell burners.
Target airflow balances to each burner
were ±2% of average; flue gas recircu-
lation balance goals were ±1% absolute
(e.g., 14 to 16% FGR for 15% average).
The modeling criteria and measure-
ment techniques necessary to achieve
this level of flow and FGR balance are
described. Field test results to confirm
that the modeling criteria in fact dupli-
cated the full-scale boiler behavior are
presented. Finally, results of a series of
modifications to achieve the flow and
FGR balance targets are presented.
3-4. "Laboratory Flow Model
Studies to Improve
Overfire Air Mixing,"
R. Thompson, Fossil
Energy Research Corp.;
D. Eskinazi, EPRI;
R. Afonso, G. Gilbert,
Dynatech R/D Co.; R. Yang,
KVB, Inc.; C. McHale, Riley
Stoker Corp.
The installation of an overfire air sys-
tem on coal-, oil-, or gas-fired utility
boilers can be an effective means of re-
ducing NOX emissions without some of
the operational or retrofit limitations of
other forms of staged combustion NOX
control. However the design of early
overfire air systems was not optimized
and their effectiveness was strongly de-
pendent on the degree of air penetra-
tion mixing and carbon burnout in the
upper furnace region. Current design
practice suggests that an overfire air ve-
locity to bulk furnace velocity ratio of
about 6 is desirable to achieve good
overfire air penetration. However, a re-
view of existing unit designs indicates a
number of overfire air systems were in-
stalled with low overfire air velocity be-
fore this design practice was accepted.
In addition, it has not been established
whether this design practice is equally
effective or optimum for all furnace fir-
ing configurations.
The objective of this research project
is to develop specific design criteria for
retrofit and new unit overfire air sys-
tems based on flow model test results.
A one-twelfth scale model has been
constructed with variable overfire air
port location and injection condition, fir-
ing configuration, and furnace aspect
ratio to study the mixing process. A
brief fundamental analysis based on jet
penetration theory was used to estab-
lish the model design criteria for simu-
lating the flowfield in tangential, op-
posed, and single-wall-fired utility
boilers. Preliminary test results for the
single-wall-fired case are reported in-
cluding overfire air concentration pro-
files in the mixing region above the in-
jection ports. The overfire air injection
velocity, port number, and location are
shown to be critical parameters in the
upper furnace mixing process.
3-5. "Status of EPDC's NOX
Control Technology,"
Kuniyoshi Fujiyama,
Electric Power
Development Co., Ltd.
EPDC has a total generating capacity
of about 10,000 MW, and 3,000 MW of
the total is by coal thermal generation.
All of the coal thermal power stations
are located near cities, and gas recircu-
lation and/or an overfire air system
(OFA) has been adopted these 10 years
for Iow-N0x operation. R&D work for
SCR De-N0x operation was started
about the same time, and commercial
operation was started 4 years ago, after
successful demonstration tests at Take-
hara Unit No. 1.
The results of our low-No,, operation
for 10 years and of SCR operation for
4 years are described in the paper.
In Takasago Thermal Power Station,
we had an accident where the evaporat-
ing tube below the OFA port burst 9
years after starting 15% OFA. Investiga-
tion revealed that thinning of the tube
was concentrated in a specific region,
and the thinning was regarded as a re-
sult of corrosion by a reducing gas.
In Isogo Power Station, where coal of
N = 1.1 to 1.3% is fired and the NOX
value for 6 to 7 years after starting oper-
ation was 500 to 600 ppm, the NOX value
was lowered to 340 from 450 by installa-
tion of 15% OFA in 1974, to 250 from 300
ppm by that of a Iow-N0x burner in
1977, and further to 150 from 160 ppm
by 30% deep stage combustion in 1980.
The results on unburned carbon vs
NOX, adoption of high performance pul-
verized coal distributor, curtain wall by
air, etc. are explained.
Operation experience on Takehara
Generator No. 1 (250 MW) and No. 3
(700 MW) are shown as the newest data
of the SCR operation.
AH plugging, the problems of IDF,
BUF vibration, and deterioration of ac-
tivity of catalysts are also referred to.
3-6. "Development of Low NOX
Cell Burners for Retrofit
Applications," Albert D.
LaRue, Larry W. Rodgers,
Babcock & Wilcox
Continuing concern about NOX emis-
sions from pre-NSPS coal-fired utility
boilers led EPRI and Babcock & Wilcox
to embark on a project to reduce NOX
emissions from cell burner combustion
equipment. Cell burners were applied
extensively in large coal-fired boilers
situated in the east-central U.S. These
boilers have generated NOX emissions
at two to three times the limit allowed
by present federal standards for new
sources. The unique design of the cell
burners was incompatible with existing
Iow-N0x burner designs. Thus, the main
objective of the multiphase project was
to develop directly retrofitable, Iow-N0x
combustion equipment for use in these
units and to develop scaling techniques
to reduce risks and predict performance
at full scale.
This paper discusses pilot-scale
(6 x 106 Btu/hr) combustion tests and
related work performed to develop a
low-NOx cell burner. Screening tests
compared performance of standard eel
burners to low-NOx alternatives. The re-
sulting Low-NOx Cell Burner achievec
NOX reductions of 65% while maintain
ing high combustion efficiency. In add!
tion, field constraints and scaling tech
niques were evaluated in preparatior
for its commercialization.
3-7. "Development of the
Low-N0x Burner for the
Pulverized-Coal-Fired
In-Furnace NOX Reduction
System," Shigeki Morita,
Tsuneo Narita, Yoshiziro
Arikawa, Isuyoshi Nawata
Fumio Koda, Tadahisa
Masai, Keizo Untsuka,
Hitachi, Ltd.
Babcock Hitachi K. K. (BHK) has deve
oped a new low-NOx burner special
designed as the "Main Burner" to I
combined with the P. C. firing I
Furnace NOX Reduction (IFNR) systei
We call this burner the Hitachi NOX R
duction Burner (HT-NR Burner). Tr
burner may be called an "In-Flarm
NOX Reduction Burner.
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3-8. "Fire-Side Corrosion in
Low-NOx Combustion
Systems," S. F. Chou,
P. L Daniels,
L. W. Rodgers,
G. J. Theus, Babcock &
Wilcox Co.; D. Eskinazi,
EPRI
Flame impingement and reducing gas
are two major concerns regarding po-
tential fireside corrosion problems in
Iow-N0z combustion systems. Flame
impingement can cause severe corro-
sion by unburned pyrites and liquid py-
rosulfate. In the reducing gas, sulfur is
released from coal as H2S, which will
sulfidize boiler tubes at furnace wall
temperatures. Laboratory test results
show that carbon steel and Type 304
stainless steel have reasonably good
corrosion resistance up to 700 and
900°F, respectively. However, thermal
cycling degrades their corrosion resis-
tance. Types 309 and 310 stainless
steels, Inconel 671, and an Fe-Cr-AI alloy
have much better corrosion resistance.
Alternate oxidizing and reducing condi-
tions are detrimental to the corrosion
resistance of the carbon steel but not
the stainless steels. Commercial
bimetallic tubing clad with stainless
steel should be of practical use in low-
NOX combustion systems.
In general, low-NOx combustion con-
ditions are more corrosive than conven-
tional boiler combustion conditions.
Careful control of operating conditions
is critical to the corrosion problems.
Combustion test results indicate that
staged combustion conditions are more
corrosive than low-NOx cell burner
combustion conditions, and the corro-
sion in the low-IMOx cell burner combus-
tion system is expected to be manage-
able.
3-9. "Extrapolation of Burner
Performance for Single
Burner Test to Field
Operation,"
R. A. Lisauskas,
D. C. Itse, Riley Stoker
Corp.; C. C. Masser,
EPA/AEERL
The extrapolation of pilot scale
NOx burner test results to coal-fired
field boilers is discussed. Single burner
test results are presented for three pilot-
scale test furnaces and two burner
scales. Three burner designs are evalu-
ated: a conventional pre-NSPS burner,
a commercial first generation Iow-N0x
burner, and a prototype second genera-
tion Iow-N0x burner. NOX emissions are
compared with field data from two util-
ity wall-fired boilers equipped with low-
NOx burners. A burner zone heat re-
lease parameter is used to account for
differences in thermal environment
between the test furnaces and field
boilers.
Session 4
Development and Application
of Fuel Staging (Reburning)
(R. Hall, EPA/AEERL, Session
Chairman)
4-1. "Pilot Scale Evaluation of
NOX Control From
Pulverized Coal
Combustion By
Reburning," W. R. Seeker,
B. J. Overmoe,
J. M. McCarthy, S. L. Chen,
G. D. Silcox,
D. W. Pershing, Energy
and Environmental
Research Corp.
This paper described results from a
research project supported by the U.S.
EPA in which a 10 x 106 Btu/hr reburn-
ing tower was designed and con-
structed for the purpose of studying re-
burning processes on a scale large
enough to involve realistic mixing phe-
nomena. The facility, which was
4 x 4 x 26 ft overall, was down-fired
with coal or gas and was refractory-
lined and water-jacketed. Multiple rows
of ports were included in the design to
allow the study of injection location,
residence time, thermal environment,
injection configuration, jet diameter and
velocity, and the important process
variables. The NOX reduction levels
achieved over uncontrolled levels were
found to be between 40 and 70%, de-
pending on the process parameters.
The results of this study indicated that
many of the process variables identified
on earlier bench-scale studies could be
directly applied to larger scale units. In
particular, increasing rich-zone resi-
dence time and furnace temperature de-
creased NOX emissions, and about 15%
reburning fuel produced a minimum in
emissions. Increasing the reburning
mixing rate was also found to decrease
NOX emissions in the exhaust. This
paper supplies general guidelines for the
application of reburning to pulverized-
coal-fired boiler furnaces.
4-2. "The Effect of Fuel
Nitrogen in Reburning
Application to a Firetube
Package Boiler,"
J.A. Mulholland, R. E. Hall,
EPA/AEERL
An experimental investigation of the
effect of volatile fule-bound nitrogen in
reburning application to a pilot-scale
fire tube package boiler is described. It is
shown that the fixed nitrogen content of
the reburning fuel is a limiting factor in
applying reburning to boilers with base-
line NOX levels of less than 250 ppm.
With reburning fuels containing more
than 0.1% nitrogen, 50% NOX reduction
was the maximum achievable when the
initial NOX level was less than 200 ppm.
For fuels containing more than 1% nitro-
gen, no reduction was possible from ini-
tial levels of less than 200 ppm. In tests
with ammonia-doped natural gas (up to
1% nitrogen), pyridine-doped distillate
fuel oil (0.5% nitrogen), and a residual
distillate fuel oil mixture (0.14% nitro-
gen), minimum net fractional conver-
sion of reburning fuel nitrogen to ex-
haust NOX was found to range from 30
to 50%. To minimize the conversion of
reburning fuel nitrogen to NOX, primary
flame excess air level is minimized and
fuel-rich reburning zone residence time
is maximized.
4-3. "Screening and
Optimization of
In-Furnace-N0x-Reduction
Processes for Refinery
Process Heater
Applications," Fernando J.
Garcia, Robert Yang,
Skillman C. Hunter, KVB,
Inc.
The effectiveness and applicability of
In-Furnace-N0x-Reduction (IFNR, also
known as reburning or fuel staging)
process in controlling NOX emissions
from refinery process heaters has been
studied. A two-phase approach was
taken first to screen the various IFNR
firing arrangements in an idealized sub-
scale test furnace for their N0x-reducing
capabilities, followed by selecting the
most promising IFNR firing arrange-
ment and evaluating its applicability in a
subscale process heater simulator. The
screening test results showed that,
while "conventional" reburning (air-
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staging plus fuel injection to create a
fuel-rich zone between the main burner
and the staging air injection point) was
only as good but not better than air-
staging in reducing NOX, the firing ar-
rangement that achieved the greatest
NOX reduction is the one called "biased
firing" which was found to be capable
of reducing stack IMOX by greater than
90% from the unstaged baseline condi-
tions. Following the screening tests, the
applicability of biased firing as both a
retrofit and a new burner concept was
further studied in a subscale process
heater simulator. The results of these
tests showed that biased firing is a vi-
able concept to be implemented for
substantial reduction of NOX emissions
from refinery process heaters.
4-4. "Evaluation of In-Furnace
NOX Reduction," H. Ikebe,
S. Miyamae, K. Makino,
K. Suzuki, J. Mogi,
Ishikawajima-Harima
Heavy Industries Co., Ltd.
Reburning by secondary fuel injected
after the main firing zone produces a
NOX reducing region in which hydrocar-
bon radicals resolve NOX into N2.
Bench-scale tests were conducted using
gas fuels and gas-phase volatile matter
evolved from pulverized coal as second-
ary fuels. The results indicated the
molar ratios (02)/(HC) and (HC)/(NO) as
well as gas temperature residence time
in the reducing region, and a kind of
secondary fuel to be the dominant vari-
ables controlling the reaction. Pilot-
scale tests using the 12 MWt furnace
were performed to see if in-furnace NOX
reduction could be applied to gas, oil,
and pulverized coal firing. While main-
taining excess O2 in the first stage com-
bustion zone at 1 to 2%, NOX reduction
of more than 50% was possible by re-
burning. In the case of commercial boil-
ers firing oil and pulverized coal, 15 to
20% NOX reduction was possible by
quasi-reburning with a conventional
burner arrangement.
4-5. "Three-Stage Pulverized
Coal Combustion System
for In-Furnace NOX
Reduction," Y. Sekiguchi,
N. Okigami, Y. Miura,
K. Sasaki, R. Tamaru,
Hitachi Zosen Corp.
A comprehensive effort was made to-
ward the development of Iow-N0x com-
bustion methods in pulverized coal
combustion, and this effort led to the
development of a new NOX reducing
combustion system called "Three-
Stage Combustion System." In this
process, pulverized coal and air are
combusted in a conventional method in
the first stage, then additional coal is
injected and NOX formed previously is
reduced to nitrogen.
Finally, more air is supplied to com-
plete combustion. The performance of
this method was tested using a small-
scale test furnace with a coal-burning
capacity of 200 kg/h at first, and then a
large-scale test was conducted at
demonstration facilities with a coal-
burning capacity of 2 t/h. It was clear
that the new combustion system pro-
vided an improved NOX suppression
rate and good combustion characteris-
tics in comparison with conventional
NOX reduction methods. This new low-
NOX combustion system has been ap-
plied to actual coal firing plants.
4-6. "Application of Reburning
for NOX Control in
Cogeneration," R. Brown,
W. C. Kuby, Acurex Corp.
This paper describes the results of a
design and experimental program to
develop a post-combustion NOX control
technique for gas-fired 1C engines and
gas turbines as applied to cogeneration.
Emissions and performance data of
both rich- and lean-burn engines were
used to develop a conceptual reburner
design to be placed between the engine
and a waste neater boiler. This reburner
design was then modeled for testing in
a 100,000 Btu/hr subscale test facility.
Parametric testing achieved 50% reduc-
tion at a fuel fraction of 30% for rich-
burn and mid-O2 range engine ex-
hausts. Lean-burn NOX reductions were
limited to 35% at the same fuel fraction.
It appears that increased temperatures
and overall fuel-rich conditions in the
reburn zone are necessary to achieve up
to 50% reduction. Other parameters ex-
plored include reburner stoichiometry,
NO input level, fuel fraction, and mixing
techniques.
Session 5
Full-Scale Boiler Application
(C. Allen, Arizona Public
Service Co., Session Chairman)
5-1. "Guidelines for Retrofit
Low NOX Combustion
Control," Richard E.
Thompson, Fossil Energy
Research Corp.;
Michael W. McElroy, EPRI
EPA has sponsored a study to deter-
mine the potential of applying retrofit
NOX controls to coal-fired utility boilers
and to develop guidelines for use by
utility boiler operators in identifying
cost-effective control options. This
paper summarizes: 1) boiler NOX emis-
sions by design type, 2) current and
emerging NOX control options, and 3) a
methodology for determining the rela-
tive retrofit potential, performance, and
cost of implementing NOX control on
boilers of various design.
Total annual NOX emissions and unit
capacity by boiler type are compared on
a national basis to provide an apprecia-
tion for the dependence of NOX emis-
sions on boiler design. The design, per-
formance, operational, and cost
characteristics of three conventional
retrofit NOX control techniques are sum-
marized. A synopsis of emerging con-
trol techniques highlights current R&D
efforts. The screening methodology for
selecting NOX control options addresses
many of the specific design and physi-
cal hardware constraints in selecting a
control method.
5-2. "Evaluation of Long-Term
NOX Reduction on
Pulverized Coal-Fired
Steam Generators,"
S. Hunter, V. P. Roman,
KVB, Inc.
Long-term NOX emission data from
eight pulverized-coal-fired steam gener-
ators were analyzed to quantify the ef-
fectiveness of various combustion mod-
ifications. All of these boilers, except
one, were modified specifically to re-
duce NOX emissions. These combustion
modifications included changes of both
a hardware and operational nature. All
of the boilers were subject to the NO,
provisions of the 1971 New Source Per-
formance Standard (NSPS).
In several instances long-term emis-
sion data for the time period before the
modification were not available. Ir
these cases the quantification of the
NOX reduction was based on the resul
of the performance test required by th<
1971 NSPS. NOX reductions ranginc
from 5.1 to 60% were determined with
out incurring significant adverse im
pacts on unit operation. NOX emissioi
levels as determined from the perform
ance tests, ranged from 146 to 473 ng/.
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(0.34 to 1.10 lb/106 Btu) before control
implementation and from 148 to 281 ng/
J (0.34 to 0.65 lb/106 Btu) after combus-
tion modifications were applied.
5-3. "Application of a
Pulverized-Coal-Fired
Low-IMOx PM Burner for
Steam Generators,"
T. Namiki, Mitsubishi
Heavy Industries, Ltd.
Mitsubishi Heavy Industries, Ltd. has
engaged in research and development
of a new technology related to coal-fired
thermal powerplants for many years,
and had developed coal-fired Iow-N0x
burners to meet the severe emissions
regulations that become more and
more severe every year. This time, we
have successfully developed and put
into practical use a pulverized-coal-fired
super low-NOx PM burner (Mitsubishi
Pulverized Fired PM Burner).
This paper introduces pulverized
coal-fired boilers with capacities of 250
t/h equipped with this PM burner that
has been installed at Iwanuma Mills of
Daishow Paper Mfg. Co. and a 350 MW
reheat unit that has been installed at
Sakata Power Station of Sakata Joint
Power Generating Co., Ltd.
5-4. "Field Evaluation of the
Distributed Mixing
Burner," B. Folsom,
A. Abele, J. Reese, Energy
and Environmental
Research Corp.
The Distributed Mixing Burner (DMB)
is a low-NOx pulverized coal burner for
wall-fired applications. It consists of a
circular burner with outboard air ports
to provide staged combustion. The cir-
cular burner operates under reducing
conditions to minimize NOX emissions
while an overall oxidizing environment
is maintained in the furnace to minimize
slagging and corrosion.
The paper presents the results of a
field evaluation of the DMB funded by
the U.S. EPA on a 98 kg/hr (215 x 103
Ib/hr) steam four-burner front-wall-fired
boiler. Prior to the DNB retrofit, field
tests were conducted on the pre-NSPS
burner originally installed in the boiler
to establish a baseline. Following DMB
installation, the boiler was operated and
tested with the DMBs for 17 months.
Under routine operation, the DMBs re-
duced NOX emissions by about 50%.
Under optimum conditions, NOX emis-
sions were reduced by about 70%.
5-5. "Designs and
Development of a Retrofit
Low NOX Burner,"
I. J. Stuart-Sheppard,
W. K. Summons,
J. A. Arnott, Ontario Hydro
Initial tests, aimed at reducing the tur-
bulence of combustion, involved re-
moving the impellers from a single row
of burners. Though it proved possible to
sustain combustion, severe roping of
the coal occurred.
Subsequent installation of venturies
substantially improved combustion
while maintaining a significant reduc-
tion in NOX. However, excessive pres-
sure drop in the primary air system was
experienced.
In light of the experience gained, a
scaled-down version of the boiler man-
ufacturer's Low-NOx Burner, suitable
for retrofitting into existing burner
openings was developed. Testing of a
single row of these burners enabled
problem areas to be identified and mod-
ifications made to bring their perform-
ance to a standard acceptable for a com-
plete retrofit. The results from the first
unit retrofitted proved the burners to be
highly effective in reducing NOX, and a
second unit was, therefore, retrofitted.
Over a period of time, substandard PF
fineness contributed to increases in un-
burned carbon which led to opacity
problems. A decision was, therefore,
made to try and modify the burners in a
way which would compensate for such
adverse influences.
Following model tests, small coal
spreaders were incorporated in the
burner of one unit. Substantial improve-
ment in flame stability was achieved en-
abling the NOX to be varied over a wide
range by adjusting burner settings. No
opacity problems were experienced,
and testing is continuing to establish
settings which minimize NOX while
maintaining an acceptable level of un-
burned carbon.
5-6. "Application of the MACT
In-Furnace NOX Removal
Process Coupled with a
Low-N0x SGR Burner,"
N. Murakami, Mitsubishi
Heavy Industries (Japan)
Mitsubishi Heavy Industries, Ltd.
(MHI) of Japan has developed the in-
furnace NOX removal process, named
MACT. The application for a new 600
MW coal/oil dual-fired supercritical unit
has been done. With the MACT, ex-
tremely Iow-N0x emissions were
achieved, coupled with a Iow-N0x firing
SGR burner, and the unit proved stable,
reliable, and easily operated.
5-7. "Long Term Corrosion and
Emission Studies of
Combustion Modification
Effects at Coal-Fired Utility
Boilers," P. S. Natanson,
R. M. Vaccaro, Exxon
Research and Engineering
Co.; J. M. Ferraro, Exxon
Chemical Co.; D. G.
Lachapelle, EPA/AEERL
Combustion modifications (CMs)
(e.g., low excess air, staged combus-
tion) can decrease NOX emissions from
coal-fired utility boilers. However, these
modifications may create chemically re-
ducing environments within the boilers
and therefore affect the rate of fireside
corrosion of boiler tubewalls. To ad-
dress this issue, several utility boilers
were characterized to determine the ef-
fects of various combustion controls
and modifications on boiler operations
and emissions. Other aspects of the re-
search program included the measure-
ment of furnace tubewall corrosion
rates, and the performance of several
30-day continuous emission monitoring
(CEM) tests for NOX and other gaseous
pollutants.
In the "as-found" (baseline) condi-
tion, all boilers were in compliance with
the applicable New Source Perform-
ance Standard (NSPS) for NOX. On the
average, the typical NOX emission rate
was 256 ng/J (0.6 lb/106 Btu or 435 vppm
at 3% O2, dry) as N02. By instituting ad-
ditional CMs, NOX emissions could be
decreased by another 20 to 40% without
adverse side effects (excessive slag-
ging, loss of control, etc.). EPA Level 1
environmental assessments (EAs), per-
formed on two of the boilers, showed
no unusual environmental hazards re-
sulting from low-NOx operation. For all
boilers tested, tubewall corrosion rates
were comparable to rates in boilers not
using CMs for NOX control, averaging
about 2 mils per year.
Session 6a
Externally Staged Combustors
(Slagging Combustors)
(Concurrent Session)
(C. Derbidge, EPRI, Session
Chairman)
-------
6a-1. "Development of a Low
NOX/SOX Burner,"
O. W. Dykema,
Rocketdyne
Division/Rockwell
International
For more than 5 years, Rockwell Inter-
national has been developing a unique
burner capable of simultaneous control
of S02 and NOX, and removal of suffi-
cient flyash to allow retrofit of gas- and
oil-fired boilers to coal with minimal de-
rating. Underlying process theory was
largely verified in a 20 GJ/hr (17 x 106
Btu/hr) pulverized-coal-fired burner and
further development at a utility pilot-
scale level (26 GJ/hr or 25 x 106 Btu/hr)
is nearing completion. A full-scale
burner demonstration (106 GJ/hr or
100 x 106 Btu/hr) is scheduled to start in
late spring of 1985.
6a-2. "NOX Control in an Air
Cooled Cyclone Coal
Combustor," B. Zauderer,
Coal Tech Corp.;
K. S. Fujimura, Southern
California Edison Co.
This paper reports on the analysis of
experiments on NOX control in a 106
Btu/hr, staged, air-cooled cyclone com-
bustor. The combustor exhausted into
two ceramic-lined vessels, which simu-
lated the radiant furnace section of a
boiler. Final combustion air was intro-
duced between the two vessels, at a
point where the cyclone combustion
gas exhaust had cooled from 3000 to
about 2200°F. The stoichiometric ratio
(SR) of the combustor was varied from
0.6 to 1.15. About a factor of 3 NOX re-
duction, to less than 100 ppm, was ob-
tained at a SR of 0.65, based on the coal
and air feedrates to the cyclone com-
bustor. The NOX results are consistent
with other experiments in a water-
cooled cyclone combustor and in con-
ventional pulverized coal flames, which
show that the minimum emissions of
the three primary fuel bound nitrogen
compounds occur at about this SR. It is
shown that the placement of the tertiary
air injection in the simulated furnace
was consistent with kinetic rate predic-
tions for optimum NOX reduction in
staged combustion. The application of
this NOX control technique to commer-
cial scale utility boilers is briefly de-
scribed. Also, a brief description is
given of experiments in which signifi-
cant reductions in the SOX emissions
were observed, as a result of limestone
injection in this cooled combustor.
6a-3. "Coal-Fired
Precombustors for
Simutaneous NOX, SOX
and Paniculate Control,"
G. C. England, J. F. La
Fond, R. Payne, Energy
and Environmental
Research Corp.
A major obstacle to the conversion of
gas- and oil-fired equipment to coal is
the high cost of controlling emissions of
particulate matter and acid rain precur-
sors (NOX, SOX). The presence of min-
eral matter in the coal and relatively
long burning time required also compli-
cated conversion. The ash formed dur-
ing combustion of coal can deposit on
heat transfer surfaces, reducing effi-
ciency and causing corrosion and ero-
sion. The volume of gas- and oil-fired
furnaces typically does not provide suf-
ficient residence time at high tempera-
tures to completely burn the solid coal
particles. Substantial derating of unit
capacity may be required in order to
minimize these potential drawbacks.
Coal-fired precombustor devices offer
the potential for simultaneous removal
of ash and reduction of NOX/SOX emis-
sions at the burner prior to the boiler or
heater furnace. This could reduce or
eliminate derating and other ash-
related problems, as well as reduce re-
quirements for exhaust gas cleanup.
The successful development of such
devices would facilitate conversion to
coal in the U.S., easing the burden of
imported fuel supplies.
This paper presents background in-
formation related to the control of ash,
SOX, and NOX in precombustors. In ad-
dition, this paper describes results of
tests in a small pilot-scale precombus-
tor conducted under EPA Contract 68-
02-3130. This program is intended to es-
tablish the potential and compatibility
of requirements for simultaneous con-
trol of all criteria pollutants.
Session 6b
Fundamental Combustion
Studies (Concurrent Session)
(J. Haebig, EPA/AEERL, Session
Chairman)
6b-1. "Mechanisms Governing
the Destruction of
Nitrogen Species During
Staged Coal
Combustion,"
J. O. L. Wendt,
K. M. Dannecker,
University of Arizona
Effects of coal composition on fuel ni-
trogen mechanism during fuel-rich
combustion of pulverized coal were ex-
perimentally investigated in a 2 kg/hr
downfired combustor. Although there is
some variation from coal to coal, the
data support the hypothesis that N2 for-
mation, NH3 formation and destruction
and NO destruction follow the Fenimore
mechanism HCN destruction is also
consistent with Fenimore, although
there appears to be a source causing
HCN formation.
6b-2. "Oxidation and Pyrolysis
of Fuel Nitrogen in a
Lignite-Both as Received
and After Ammonium
Ion-Exchange,"
A. F. Sarofim,
L. D.Timothy,
J. M. Beer,
Massachusetts Institute
of Technology
The dependence of the conversion of
the organically bound nitrogen in coal
to NO on the volatility and amount of
fuel nitrogen was studied by the pyroly-
sis and oxidation of a low rank Montana
coal, both as-received and after ion-
exchange with ammonium acetate. The
nitrogen content of the coal was in-
creased on treatment from 1.11 to
2.34% by weight (dry). Nitrogen reten-
tion by the chars obtained during pyrol-
ysis of both the raw and treated coals
was measured over a temperature
range of 550 to 1650 K. The added nitro-
gen was more volatile being released
completely by 1400 K, compared to 60%
release of the nitrogen in the untreated
coal at 1400 K. Conversion of the nitro-
gen to NO for combustion in different
oxygen concentrations was found to
vary from 35 to 55%, with the lower ni-
trogen content untreated coal having
slightly higher conversion efficiencies
than the treated coal.
6b-3. "Reduction of NOX
Emission from Natural
Gas Flames by Staged
Fuel Injection,"
J. M. Beer,
W. F. Farmayan,
-------
M. Togan, Tae-U Yu,
Massachusetts Institute
of Technology
One of the major thrusts of the exper-
imental effort was to clearly differenti-
ate between temperature and stoichio-
metric effects on overall NOX emission.
In considering the problem of differ-
entiating temperature and stoichiomet-
ric effects on NO emissions, particularly
when the various staging configura-
tions are compared, it would of course
be desirable to maintain as similar a
temperature history in the furnace for
each case as possible. However, the
temperature history for each case could
not be identical. Two parameters were
identified as having gross effects on the
average temperature of the combustion
mixture which merited close examina-
tion and control when various staging
strategies were studied.
6b-4. "NOX Prediction for
Practical Pulverized Coal
Reactors," L Douglas
Smoot, Scott C. Hill,
Phillip J. Smith, Brigham
Young University
The model of nitrogen pollutant for-
mation and destruction in pulverized
coal reactors is briefly outlined and then
evaluated by comparisons of predic-
tions with measurements. The model
incorporates effects of turbulence on
NO reactions, and subsequent predic-
tions show these effects to be impor-
tant. Model applications show effects of
key parameters on NO emissions and
illustrate the use of the NO model for
interpreting experimental results. The
model predicts the observed initial de-
crease followed by a gradual increase in
NO emissions with increased swirl
number. The model also predicts the
measured increase in NO emissions
with increased stoichiometric ratio; but,
at higher SR values, the model under-
predicts NO concentrations, partly be-
cause of increased thermal NO levels
which were not considered. The model
also predicts the observed increase in
NO with a decrease in particle size and
increase in moisture percentage. Re-
sults suggest that nitrogen release dur-
ing devolatilization and gas-phase reac-
tions of HCN and oxygen control NO
formation, while fuel nitrogen conver-
sion to HCN may be near quantitative
and rapid. According to the predictions,
NO reduction is dominated by HCN-NO
reactions and not by the char-NO reac-
tions. Practical application of the
method to pulverized coal reactors is
discussed.
6b-5. "Optimized Low-N0x
Pulverized Coal
Combustion by Zone
Control," Ken Okazaki,
Kazutomo Ohtake,
Toyohashi University of
Technology
Zone control is one of the most effec-
tive technologies to minimize NOX for-
mation in the pulverized coal combus-
tion furnace. To get the fundamental
and general concept for the optimiza-
tion of low-NOx pulverized coal com-
bustion by zone control: (1) separated
influences of various basic factors af-
fecting NO formation behaviors were
derived by use of a one-dimensional
combustion furnace; and (2) an optimal
condition for zone control was in-
vestigated by experiments of one-
dimensional multistage combustion.
These experimental investigations
have led to the following important re-
sults. The NO formation rate in the early
stage of combustion process increases
with the oxygen-fuel stoichiometric
ratio for large particles, decreases with
the particle size, and less effect by the
stoichiometric ratio appears for small
particles. The conversion ratio from fuel
N to NO decreases with nitrogen con-
tent and increases with the stoichiomet-
ric ratio, especially for high volatile
coals, and temperature has little effect
on it except for fuel-rich conditions for
high volatile coals. As for zone control,
most effective reduction of NO was at-
tained by setting the reduction zone just
after the initial NO formation zone, and
the oxygen-fuel stoichiometric ratio of
0.8 is preferable for the effective reduc-
tion of NO without increases of un-
burned materials.
Session 7
Advanced Power Plants
(Concurrent Session)
(D. Teixeira, PG&E, Session
Chairman)
7-1. "NOX Control and
Atmospheric Fluidized-Bed
Combustors," E. Petrill,
W. C. Howe,
T. C. Derbidge, EPRI;
R. J. Divilo, Pope
Engineers
One of several advantages of burning
coal in atmospheric fluidized-bed com-
bustion (AFBC) boilers for electric
power generation is the inherent low
emission of NOX. Because of the many
advantages of AFBC, EPRI is actively
promoting development of both bub-
bling and circulating fluidized-bed com-
bustion technology for utility applica-
tions through involvement in two rest
facilities and three utility-scale demon-
stration projects.
Pilot-scale and industrial AFBC units
have shown NOX emissions to fall well
below those from both conventional
and advanced pulverized-coal-fired
boilers, as well as easily meet the cur-
rent New Source Performance Stand-
ards (NSPS) for coal. It is expected that
utility-scale units will also meet NSPS.
Further reduction of NOX emissions in
a bubbling bed by air staging was inves-
tigated in an EPRI project. The study,
conducted by Babcock & Wilcox at
EPRI's 6 x 6 ft FBC facility at B&W's Al-
liance Research Center, indicated that
up to 50% reduction of NOX is possible.
However, the project also identified per-
formance and reliability issues that
must be solved before operation at min-
imum NOX conditions is feasible.
7-2. "The Cool Water Project
Clean Power from Coal,"
R. H. Wolk, N. A. Holt,
EPRI
The Cool Water project is a 100 MW
(net electrical output) integrated coal
gasifier combined cycle project that
produces the cleanest power generated
from coal that the world has ever seen.
Design goals for gas turbine stack emis-
sions are 9 ppm SOX (0.033 lb/106 Btu
fuel), 27 ppm NOX (0.065 lb/106 Btu fuel),
and 0.01 Ib of particulates/106 Btu fuel
for operations on low sulfur Utah coal.
All of these goals have been exceeded.
Other products from the plant are bright
yellow sulfur which is sold commer-
cially and glassy nonleachable slag
which is disposed of in an onsite clay-
lined pit.
In late 1985 and early 1986, a series of
test runs are scheduled on high-sulfur
Illinois and Pittsburgh coals. Sulfur
emissions for those coals are designed
to be 175 Ib/hr which corresponds to
97% sulfur removal.
The plant is located at the Cool Water
station of the Southern California
Edison Company in Daggett, CA. Initial
commercial operation began in late
June 1984, about 6 weeks after the com-
-------
pletion of construction which required
28 months. The construction and start-
up cost was $263 million, which was
about 10% below budget.
In this paper, the plant is described
with specific emphasis given to the ap-
proach to NOX control.
Session 8a
Flue Gas Treatment
(Concurrent Session)
(E. Cichanowicz, EPRI, Session
Chairman)
8a-1. "Operating Experiences
of Southern California
Edison's 107.5 MW
Selective Catalytic
Reduction DeNOx
System," Harold A. Kerry,
Alexander Weir, Jr.,
Southern California
Edison Co.
The Southern California Edison Com-
pany's 107.5 MW Selective Catalytic
DeNOx System has been tested to de-
velop performance and operational
data on this post-combustion NOX re-
moval system. Tests have been con-
ducted for more than 2 years. This
paper reviews operational experiences
from the system.
8a-2. "Reduction of
NOx-Emissions for Brown
Coal Combustion
Systems in the Federal
Republic of Germany,"
K.R. G. Hein, J. Konig,
V.Hoppe,
Rheinisch-Westfalisches
Elektrizitatswerk
Stringent environmental standards in
the Federal Republic of Germany re-
quire the application of NOx-control
techniques for both new and existing
powerplants with a capacity of >50
MWt. Also it is expected that all units
should be fully equipped with denitrifi-
cation installations before the end of
this decade.
Among the major sources of primary
energy, brown coal is of great impor-
tance because almost 30% of the elec-
tricity production is based on this fuel.
Due to properties which differ widely
from bituminous coals, also different
combustion systems have to be used.
As a consequence specific flue gas con-
ditions with regard to composition and
temperature prevail.
Therefore, the direct application of
N0x-removal techniques, which are op-
erating since some years abroad, is im-
possible at present, and further devel-
opment is needed.
After a brief introduction of fuel-
related problems with brown coal for
utility operation, the paper describes
the available method for NOx-reduction.
Particular emphasis is on the removal of
NOX from flue gases. Various technical
solutions for the application of the SCR-
technique, as well as the combination
with FGD systems, are introduced, and
first results from pilot studies are pre-
sented.
8a-3. "Introduction of
IHI-Denitrification System
for Coal Fired Steam
Generator," H. Aoki,
T. Suzuki, R. Ishimoto,
Ishikawajima-Harima
Heavy Industries Co., Ltd.
The application of a dentrification
system is widely considered for coal-
fired steam generators not only in
Japan but also in the world. For a coal-
fired steam generator, the erosion and
plugging of the catalyst are the major
problem for high ash flue gas; further-
more, NH4HS04, which can be pro-
duced by reaction of the injected NH3
and S03 converted from S02 in the flue
gas, will be deposited on the surface of
the heating elements of GAH. As for the
countermeasures of the above items,
proper grid dimension of 7.5 mm,
proper linear gas velocity of 5 to about
6 m/s at the design point, and vertical
downward gas flow arrangements were
selected, and then three IHI denitrifica-
tion systems for coal-fired utility power-
plants have been continuously operat-
ing with excellent performance for 1 or
2 years. The sootblower could be
omitted from the denitrification system.
Denitrification performance of more
than 80% has been kept for more than
2 years.
8a-4. "Thermal DeNOx
Technology Update,"
Boyd E. Hurst, Exxon
Research and
Engineering Co.
The original thermal De-N0x installa-
tions involved positioning a gridwork of
pipes in the flue gas stream for injecting
a mixture of NH3 and carrier air or
steam. In the most recent designs, the
injection grids have been replaced by
wall injectors which offer many advan-
tages, such as higher performance,
lower costs, better load following, and
lower maintenance. Also, development
of a fundamental kinetic model of the
process chemistry and a three-
dimensional flow model have provided
significant process optimization capa-
bility.
One application of thermal De-NOx in-
corporating the most recent technology
involves a 440,000 Ib/hr boiler generat-
ing steam and power in a Japanese
chemical plant. In this installation, 70%
De-NOx was achieved through utiliza-
tion of the optimized design techniques
at a cost about 20% of a comparable
selective catalytic reduction facility.
Other advantages of the most recent
technology include the ability to deal
more successfully with particulate-
laden flue gas streams and methods of
minimizing or eliminating effects of am-
monium salts in the exhaust flue gas. In
its present form, thermal De-N0x offers
a highly developed, practical means of
achieving deep NOX reduction in all
types of stationary-fired equipment.
8a-5. "Application of DeNOx
Technologies in the
Federal Republic of
Germany and Europe,"
O. Rentz, W. Heer,
University of Karlsruhe
(Th)
In view of the present extent of dam
age, the state government of Bader
Wurttemberg felt compelled, in agree
ment with operators of large boile
installations, to arrange programs fc
the far-reaching reduction of Emissions
whereby previous demands of the Go\
ernment Ordinance for Large Boiler Ir
stallations (GFAVO) were surpasse<
This concerned, first, all the polluai
S02 in the Electricity Supply Sectc
(EVU), a program which was complete
in 1983 and which finally led to a redu<
tion in SO2 emissions from about 86,OC
to about 20,000 t/a. Subsequently, £
analogous program was agreed on fi
the pollutant NOX from coal-fired pow
stations. This was based on the fixe
target limit of 200 mg N0x/m3 (=1(
vpm), which was agreed on in Janua
1984 between operators, equipme
suppliers, and the state governmer
both for dry- and wet-bottom boilei
This emission level is to be observed f
10
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dry-bottom boilers until 1988, and for
wet-bottom boilers until 1990, in both
cases for new and existing plants. The
programs mentioned up to now con-
cern only the Electricity Supply Sector
and here in the first instance coal-fired
installations. A further program for the
pollutants SO2 and NOX, with regard to
boilers outside the utility sector and
nonboiler applications, is being pre-
pared and will probably be approved to-
ward the end of 1985.
The Baden-Wurttemberg program
was thus, as a program covering a
whole area, the first of its kind; in the
meantime, however, analogous pro-
grams from other federal states now
exist.
8a-6. "Operating Experience on
SCR System for Steam
Generators," K. Suyama,
Mitsubishi Heavy
Industries, Ltd.
Since the first commercial SCR sys-
tem was supplied in 1976, many SCR
systems for steam generators were sup-
plied by Mitsubishi Heavy Industries,
Ltd. (MHI), and successful operations
have been experienced.
This paper describes experiences of
the existing SCR system for a coal-fired
steam generator and outlines an SCR
system for a combined cycle power-
plant.
The SCR system for a coal-fired unit at
Chugoku Electric—Shimonoseki No. 1
unit (175 MW)—was installed in 1980
and has been operating for more than
5 years (more than 35,000 hours from
initial operation).
In addition to the above, SCR systems
on heat recovery steam generators cou-
pled with gas turbines have recently
started their commercial operation at
Tohoku Electric's Higashi-Niigata unit
No. 3. The unit is a 1,090 MW combined
cycle plant composed of two 545 MW
trains. Operating results of the coal-
fired SCR system and features of the
combined cycle plant are summarized
in this paper.
8a-7. "Economics of NOX, SO2,
and Ash Control Systems
for Coal-Fired Utility
Powerplants,"
J. D. Maxwell,
L. R. Humphries,
Tennessee Valley
Authority
An EPA-sponsored economic evalua-
tion was made of three processes to re-
duce NOX, SC>2, and ash emissions from
coal-fired utility powerplants: one is
based on a 3.5% sulfur eastern bitumi-
nous coal, and the other two, on 0.7%
sulfur western subbituminous coal. NOX
control is based on an 80% reduction
from current new source performance
standards (NSPS); and S02 and flyash
control are based on meeting current
NSPS. Selective catalytic reduction (SR)
is used for NOX control with both coals.
Limestone scrubbing and a cold-side
electrostatic percipitator (ESP) are used
with the 3.5% sulfur coal. Lime spray
dryer flue gas desulfurization (FGD) and
a baghouse for particulate collection are
used with one 0.7% coal, and limestone
scrubbing and a hot-side ESP with the
other.
The economics consist of detailed
breakdowns of the capital investments
and annual revenue requirements. For
systems based on a 500-MW power-
plant, capital investments range from
$167 to $187 million (333 to 373 $/kW)
and first-year annual revenue require-
ments from $54 to $60 million (29 to 33
mills/kWh). The 3.5% sulfur coal case is
highest because of the higher S02 con-
trol costs. The case with the spray dryer
and baghouse is marginally lower in
cost than that with limestone scrubbing
and hot-side ESP. Costs for NOX control
range from 25 to 50% of the total costs,
largely because of the high catalyst
cost. The costs of the overall systems
and the relationship of the component
costs are complexly interrelated be-
cause of the interactions of the three
processes.
Session 8b
Stationary Engines and
Industrial Process Systems
(Concurrent Session)
(J. McSorley, EPA/AEERL,
Session Chairman)
8b-1. "Utilization of Methanol
as Fuel for a Gas Turbine
Cogeneration Plant,"
Dale E. Shore, Gary H.
Shiomoto, KVB, Inc.;
Gerald R. Bemis,
California Energy
Commission
A field test demonstration of the use
of methanol in an industrial-sized gas
turbine cogeneration unit was con-
ducted in 1984 at the Central Heating
Plant of the University of California at
Davis. This program, sponsored by the
California Energy Commission, was one
of four full-scale demonstrations of the
use of clean fuels in mobile and station-
ary engine applications. These demon-
stration programs were directed toward
the evaluation of clean fuels potentially
derived from coal, for meeting Califor-
nia's future energy needs.
A 3,250 kW Allison 501-KB gas tur-
bine, designed originally for either natu-
ral gas or distillate fuel oil operation,
was converted to methanol and oper-
ated for 1036 hrs. A methanol storage
and handling facility for fueling the en-
gine was designed and built onsite. En-
gine modifications specific to the utiliza-
tion of methanol and preliminary test
work of the specialized components
were performed by the turbine manu-
factuer. The components were then in-
stalled on the engine, and the unit was
operated on methanol. Emissions and
performance data were monitored
throughout the test. The relatively low-
NOX emissions expected from methanol
operation were further reduced by the
implementation of water injection via
mixing with the methanol before being
supplied to the engine. Engine operat-
ing problems attributable to methanol
were not encountered during the
demonstration testing; therefore, en-
gine performance was judged satisfac-
tory. However, difficulties of methanol
pumping compatibility with the engine-
driven, high-pressure fuel pump neces-
sitated the use of an off-board centrifu-
gal pump to complete the program.
8b-2. "Development and
Field-Demonstration of a
Low-NOx Burner for
TEOR Steamers,"
G. England, Y. Kwan,
R. Payne, Energy and
Environmental Research
This paper describes the results ob-
tained in a program to demonstrate in
the field a full-scale 16 MWt prototype
Iow-N0x burner for thermally enhanced
oil recovery (TEOR) steam generators
which burn high-nitrogen crude oils.
NOX emissions from these TEOR
"steamers" have been linked with dete-
riorating air quality in Kern County, CA,
and stringent local regulations have
been promulgated limiting these emis-
sions to preserve ambient air quality.
These regulations can potentially re-
strict oil production in Kern County.
The burner described in this paper is
11
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designed based on a two-stage com-
bustion concept developed from earlier
bench- and pilot-scale work. The con-
cept comprises physically separate
zones in which conditions have been
optimized to minimize both fuel and
thermal NO formation.
The full-scale 16 MWt commercial
prototype burner has been evaluated in
a laboratory test furnace and was suc-
cessfully retrofitted to a field-operating
steam generator in Kern County. Re-
sults of field test firing heavy crude oil
(0.83%N) showed that NOX emissions
below 70 ppm (at 3% excess 02 with low
CO and smoke emissions) could be
achieved with acceptable flame condi-
tions in the steamer radiant section. De-
tailed emissions characterization also
showed that emissions of particulates
and organic compounds were well be-
low allowable levels. The burner is cur-
rently still operating in the Kern Front
oilfield.
8b-3. "Heavy Oil Low-NOx
Burner Application to an
Oil Field
Steamer-Emissions
Measurements,"
H. Mason, C. Castaldini,
L Waterland,
R. DeRosier, Acurex
Corporation.
Comprehensive emission measure-
ments and 30-day flue gas monitoring
were performed on a 16 MW (55 x 106
Btu/hr) enhanced oil recovery steam
generator equipped with the EPA low-
NOX burner firing high-nitrogen crude.
The 1-day comprehensive measure-
ments included source assessment
sampling system (SASS) quantification
of semivolatile organics and 73 trace el-
ements; volatile organic sampling train
(VOST) quantitation of volatile organic
priority pollutants; EPA Method 5/8 for
paniculate and SOX; controlled conden-
sation system (CCS) for SOX; Andersen
impactors for particle size distribution;
grab samples for N20; and continuous
flue gas monitoring. NOX emissions
during the comprehensive tests aver-
aged 70 ppm at 3% 02, well below the
target level of 85 ppm. CO emissions
were below 30 ppm, and SO2 averaged
about 550 ppm. Solid particulates were
emitted at about 27 ng/J (96 mg/dscm);
condensible particulates were about
half that level. Volatile organics (ben-
zene, toluene, and ethylbenzene) were
measured in the 0.4 to 20 ppb range.
Semivolatile organics (naphthalene and
phenol) were detected in the 0.3 ppb
range. Subsequent continuous monitor-
ing of flue gas criteria emissions
showed NOX blow 80 ppm at 3% 02 with
an average 70 ppm. CO emissions were
generally less than 30 ppm.
8b-4. "Reduction of Nitric
Oxide Emissions on a
Full-Scale Cement Kiln
Using Primary Air
Vitiation," R. C. Benson,
S. C. Hunter, KVB, Inc.
KVB has been funded by the U. S. EPA
to conduct research for emission reduc-
tion from industrial processes. One
phase of this research effort concerns
reduction from cement kilns. Tests were
conducted on a 1100 ton/day long, dry
process cement kiln to evaluate the ef-
fect of primary air vitiation on NO emis-
sions. Primary vitiation was accom-
plished by injecting nitrogen gas into
the primary air. As-found test results (17
days, 89.75 hr) prior to the nitrogen in-
jection test were used to assess the in-
herent variability of the cement-making
process. The NO emissions average
about 8 Ib NO2/ton of clfrrker^and varied
approximately 30% during the as-found
test series. Lowering kiln exit oxygen
from 1.8 to 0.7% reduced NO by 15 to
20%. Three days of nitrogen injection
tests for primary air vitiation were also
performed at the test site. Although the
testing demonstrated that nitrogen in-
jection will reduce NO, the extent of re-
duction is extremely viable and is based
on the operations and kiln feed at the
time. NO mass emissions did decrease
20 to 30%, based on altering the burning
zone temperature profile (2550 to
2490°F), lowering the primary air O2
from 21 to 13% and maintaining a con-
stant kiln exit oxygen of 1.5%. No deteri-
oration of clinker quality was observed.
8b-5. "IMOX Control for
Glass-Melting Tanks,"
F. Richard Kurzynske, Gas
Research Institute;
Donald K. Fleming,
Institute of Gas
Technology
The Gas Research Institute (GRI) is
undertaking a program to evaluate fac-
tors that influence the production of
NOX in glass-melting tanks. This discus-
sion presents the results to date of the
ongoing program, as developed under
contract by the Institute of Gas Technol-
ogy (IGT).
Glass melting is a high-temperature
operation, generally employing regen-
erative furnaces with preheat tempera-
ture for the combustion air of 2000 to
2300°F. Consequently, an uncontrolled
glass-melting tank may produce NOX
concentrations of 3000 ppm. Tech-
niques for reducing these emissions are
being evaluated in this program. Work
has advanced through pilot-scale test-
ing, and the results from that effort have
been correlated to indicate the effects of
temperature, excess air utilization, and
combustion geometry factors. Staged
combustion (both air and fuel and flue
gas recirculation) also have been evalu-
ated. Testing is now underway in a com-
mercial furnace to determine scale-up
factors for the control parameters.
8b-6. "Diesel Engine NOX
Control with SCR,"
J. Wasser, R. B. Perry,
U. S. EPA/AEERL
EPA's Air and Energy Engineering Re-
search Laboratory is conducting a long-
term test evaluation of a selective cata-
lytic reduction (SCR) system on a
stationary diesel engine. The overall
goal of this project is to establish the
NOX reduction performance of a diesel
SCR unit over a 4000-hr period. This
paper reports the interim results ob-
tained during the first 2300 hr of opera-
tion. For most of the first half of the test
program, NOX reductions of over 90%
were obtained. However, as the 2000-hr
point was approached, a drop in NO,
reduction (below 80%) was experi-
enced. Cleaning restored part of the cat-
alyst's original activity, and the test pro-
gram continued.
8b-7. "Environmental
Assessment of Catalytic
Reduction of
Natural-Gas-Fired
Engines," C. Castaldini,
L. R. Waterland,
H. B. Mason, Acurex
Corp.
Field tests were performed on tw<
large-bore natural-gas-fired reciprocat
ing internal combustion engines, om
rich-burn and one lean-burn, equippei
with catalytic gas treatment systems fo
NOX control. The rich-burn engine wa
equipped with a nonselective catalyti
reduction (NSCR) system in which re
ducing gases (CO and unburned hydrc
12
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carbon) reduce NO and N2. The lean-
burn engine was equipped with a
selective catalytic reduction (SCR) sys-
tem in which NHs injected in the engine
exhaust gas acts as the reducing agent
for IMOX control. The test program for
each engine consisted of comprehen-
sive emission measurements for NOX,
CO, unburned hydrocarbon (HC), C02,
and 02 by continuous monitors; partic-
ulate, cyanide, NH3, volatile and
semivolatile organics; and trace metals
at catalyst inlet and outlet. In addition,
15-day continuous emission monitoring
was performed to record catalyst per-
formance under extended typical en-
gine operation: NOX reduction by the
NSCR system ranged between 54 and
81% during the comprehensive engine
tests, but degraded to below 40% dur-
ing the extended monitoring, because
of changes in engine air/fuel (A/F) ratio.
The test engine was not equipped with
an A/F controller. HC, CO, and total or-
ganic levels decreased across the cata-
lyst, while both cyanide and NH3 emis-
sions increased, SCR NOX reduction
performance for the lean engine was
constant at about 80%. NH3 concentra-
tion at the SCR outlet averaged about
90 ppm.
Session 9a
Overview of Furnace Sorbent
Injection SO2 Control
(Concurrent Session)
(R. Hangebrauck, EPA/AEERL,
Session Chairman)
9a-1. "Review of International
Development Activities
for Furnace Sorbent
Injection," Dan V.
Giovanni, Electric Power
Technologies, Inc.
At the 1982 Joint Symposium on Sta-
tionary Combustion NOX Control in Dal-
las, TX, an entire session was devoted
to discussing emission control proc-
esses based on dry injection of calcium
sorbents to meet SO2 regulations for
coal-fired powerplants. In November
1984, EPRI and EPA sponsored the 1st
Joint Symposium on Dry SO2 and
Simultaneous S02/NOX Control Tech-
nologies in San Diego, CA. Forty-six
papers were presented, addressing the
latest advances in fundamental re-
search and process design, powerplant
integration and economic issues, and
results from field applications. The
scope of technical information dis-
cussed at the symposium was a reflec-
tion of the significant and widespread
developmental activities currently in
progress, which involve furnace sor-
bent injection (FSI) for SO2 control. This
paper attempts to summarize that infor-
mation by defining the current status of
FSI process developments, acknowl-
edging advances in process under-
standing and design, and identifying yet
unresolved technical issues.
9a-2. "Technical Status of
EPA's LIMB Program,"
G. Blair Martin, James H.
Abbott, U. S. EPA/AEERL
SOxand NOX, two pollutants resulting
from the combustion of coal, are be-
lieved to be major precursors of acid
rain. Limestone Injection Multistage
Burners (LIMB) is a potentially low-cost
technology for control of SOX and NOX
from existing utility and industrial boil-
ers. The LIMB R&D program has pro-
vided a detailed understanding of the
key processes governing sulfur capture
with sorbents. While it appears that
limestone alone will not achieve pro-
gram goals, several other promising
sorbents have been identified. Based on
the R&D results and cost estimates for
use of these sorbents, LIMB shows sub-
stantial promise as a SOX and NOX con-
trol technology for retrofit applications.
The ongoing R&D program should re-
solve the remaining technical questions
and provide a basis for widespread pri-
vate sector commercialization. This
paper summarizes the technical status
of LIMB-related R&D.
9a-3. "EPRI's Research
Program on Furnace
Sorbent Injection,"
M. McElroy, EPRI
The concept of injecting calcium-
based alkaline sorbent materials di-
rectly into the furnace of coal-fired util-
ity boilers to reduce S02 emissions is
the subject of major research and devel-
opment programs in the U.S. and
abroad. EPRI is contributing to these ef-
forts by sponsoring an experimental
test program to develop an understand-
ing of fundamental process chemistry
and optimizing the process for maxi-
mum SO2 removal and calcium utiliza-
tion. Complementary EPRI projects are
addressing engineering system design,
economic, and powerplant integration
issues. These projects will provide the
technical basis for designing and oper-
ating prototype furnace sorbent injec-
tion systems at 50 to 150 MW utility
boilers, which is the next logical step
toward commercializing the process.
Session 9b
Fuel and Combustion
Modifications for
Commercial/Industrial Boilers
(Concurrent Session)
(J. Wasser, EPA/AEERL,
Session Chairman)
9b-1. "Combustion
Modification Techniques
for Coal-Fired Stoker
Boilers," G. C. Quartucy,
H. J. Buening, R. J. Yang,
KVB, Inc.
Combustion modification techniques
were applied to full-scale coal-fired
stoker boilers for the purposes of opti-
mizing boiler operation and reducing
emissions. Five full-scale stoker boilers
of different designs were evaluated.
Three of these (two spreader stoker and
one vibrating grate stoker) boilers were
fitted with flue gas recirculation for the
purposes of reducing NOX emissions
and improving boiler efficiency. Test re-
sults snowed that boiler efficiency im-
provement and NOX reduction can be
achieved with flue gas recirculation for
spreader stoker boilers with intermedi-
ate or high minimum excess oxygen
levels. Its application to mass-fed stoker
boilers (which typically have very short
combustion zones) and spreader stoker
boilers with very low baseline excess
oxygen levels (5% or lower) was not
successful. NOX emissions were found
to decrease with decreasing excess oxy-
gen levels for spreader stoker boilers,
but were relatively independent of ex-
cess oxygen levels for mass-fed stoker
boilers. Overfire air system modifica-
tions to enhance jet penetration re-
sulted in significant stack opacity reduc-
tion. Particulate emissions were found
to be correctable to the third power of
bulk combustion product gas velocity
(volumetric throughput rate divided by
boiler cross-sectional area). This indi-
cates that reductions in excess air level
will result in efficiency improvement,
NOX reduction, and significant particu-
late emissions reduction.
9b-2. "Emissions Assessment
of Coal/Water-Slurry-
Fired Industrial Boilers,"
-------
L. R. Waterland,
R. DeRosier, D. Van
Buren, and H. B. Mason,
Acurex Corporation
This paper describes emission results
obtained from field testing of two indus-
trial boilers test-fired with coal/water
slurries (CWS). Emission measure-
ments performed included continuous
monitoring of flue gas emissions;
source assessment sampling system
(SASS) sampling of flue gas emissions,
with subsequent laboratory analysis of
samples to obtain total flue gas organ-
ics in two boiling point ranges, com-
pound category information within
these ranges, specific quantitation of
the semivolatile organic priority pollu-
tants, and flue gas concentrations of 73
trace elements; EPA Method 5 sampling
for particulate; EPA Method 8 sampling
for SO2 and SOj emissions; volatile or-
ganic sampling train (VOST) testing for
volatile organic priority pollutant emis-
sions; gas grab sampling for onsite (^
to C6 hydrocarbon emission measure-
ments; gas grab sampling for N2 emis-
sion measurements; and grab sampling
of the CWS fuel and ash streams for in-
organic composition determination.
Complete emissions measurement re-
sults for the two units are presented.
9b-3. "Development of
Low-IMG* Combustion for
Industrial Application,"
Tomio Suzuki, Kotaro
Morimoto, Keiichi Ohtani,
Ryuichi Odawara, Tatsuo
Kohno, Yuichi Matsuda,
Mamore Suyari, Kobe
Steel, Ltd.
Low-NOx emission combustion has
been developed for industrial furnaces,
boilers, palletizing kilns, cement plants,
and gas turbines. More than 350 low-
NOX burners of the slow-combustion
type for industrial furnaces have shown
a reduction of 30 to 70% in NOX value
and 5 to 10% in fuel consumption. INOX
emission reduction of low-NOx burners
for boilers has attained 30 to 60% in the
17 boilers of 2 to 15 t/h evaporation. The
boiler efficiency of Iow-N0x burners
was higher than that of conventional
burners by 2%. The NOX value of low-
NOx burners for pelletizing kilns has de-
creased with an increase in multifuel-fir-
ing percentage of coal in coke-oven gas
and coal firing. Low-N0x combustion of
the Dual Combustion and Denitration
(DD) process for a 3600 t/d cement plant
has decreased to 110 ppm (10% O2) in
NOX value and 735 kcal/kg-cl in fuel con-
sumption. A new low-NOx combustor of
a premixed, prevaporized, and fuel-lean
type for gas turbines has resulted in an
NOX reduction of about 90%.
9b-4. "Emissions Assessment
of Cofiring Coal and
Waste Plastic in a
Commercial Boiler,"
L. R. Waterland,
R. DeRosier,
H. I. Lips, H. B. Mason,
Acurex Corporation
This paper describes emission results
from field testing a stoker-fired com-
mercial boiler firing a coal/waste plastic
mixture. The two tests were performed;
one with the unit firing its typical coal
fuel (test 1), and one with shredded
waste polyethylene terphthalate (PET)
beverage bottles added to the coal to
about 16% by weight in the mixed fuel
(test 2). NOX, total unburned hydrocar-
bon (TUHC), and solid particulate emis-
sions were relatively unchanged for the
two tests as was the emitted particle
size distribution. SOX emission de-
creased with the coal/PET fuel in keep-
ing with its lowered sulfur content; av-
erage CO emissions were also
decreased. Flue gas emissions of most
trace elements were comparable for
both tests, as were the trace element
compositions of corresponding ash
streams. However, lead emissions were
significantly increased for test 2. This
increase reflects the increased lead con-
tent of the mixed coal/PET fuel. The cy-
clone hopper ash for the coal/PET test
had consistently lowered teachable
trace element and anion content than
that for the coal fuel test. Total flue gas
organic emissions were comparable for
both tests, although levels of several
semivolatile priority pollutants were
higher for test 2.
9b-5. "A Low-NOx Burner for
Gas-Fired Firetube
Boilers," John P.
Kesslring, Wayne V. Krill,
Alzeta Corporation.
A field evaluation has been con-
ducted, sponsored by the Gas Research
Institute, to evaluate the durability of
the fiber burner in gas-fired firetube
boilers. The fiber burner is a radiant sur-
face burner that typically operates with
NOX emissions of 15 ppm, CO emis-
sions of 20 ppm, and essentially no hy-
drocarbons. Under this program, four
firetube boilers ranging in size from 245
to 980 kW (25 to 100 hp) were retrofit
with the fiber burner and operated for
up to 24 months. Tests of the burners
installed at these sites show a 1 to
2 percentage point increase in effi-
ciency, 80% reduction in NOX, and up to
80% reduction in CO. In addition, the
ability of the burner to allow increased
boiler loads has been demonstrated,
and flame noise has been virtually elim-
inated.
14
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S. Peralo is with Acurex Corporation, Mountain View, CA 94039.
Michael C. Osborne is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Proceedings: 1985 Joint
Symposium on Stationary Combustion /VO» Control:"
"Volume 1. Utility Boiler Applications," (Order No. PB 86-225 042/AS; Cost:
$52.95, subject to change)
"Volume 2. Industrial Processes, Fundamental Studies, and Slagging
Combustors, "(Order No. PB 86-225 059'/AS; Cost: $34.95. subject to change)
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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