United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S7-89/015 May 1990
&EPA Project Summary
Field Evaluation of Low-
Emission Coal Burner
Technology on Utility Boilers
A.R. Abele, J. F. LaFond, J.A. Cole, G.S. Kindt, W.C. Li, E. C. Moller, R. Payne.
and J. L. Reese
This report summarizes an
extensive field evaluation of low-
emission coal burner technology on
utility boilers. The experimental
studies described fall into four main
areas:
• Distributed Mixing Burner (DMB)
Evaluatlon-in which a prototype
DMB and two commercial Babcock
& Wilcox burners were tested at
scales of 60 and 120 x 106 Btu/hr
(17.5 and 35 MW) in a large
experimental test furnace. The
evaluation focused on combustion
performance, NOX emissions, and
the application of sorbent injection
for SO2 control.
• Second Generation Low-NOx
Burners-in which the performance
of three 78 x 106 Btu/hr (22.9 MW)
Babcock & Wilcox low-NOx burners
was evaluated and optimized. Key
performance criteria included NOX
emissions, flame length, and
combustion efficiency. Results
from these tests were used to
recommend a burner for
application in the EPA LIMB
(Limestone Injection Multistage
Burner) demonstration program at
Edgewater Station Unit 4.
• Field Evaluations-in which field
testing was performed at two
different utility boiler sites. The
objective of this testing was to
compare commercial burner
performance under field and test
furnace conditions, as a basis for
the scaling of NOX emissions.
• Alternate concepts--in which
experimental studies were
conducted on coal-fired
precombustor concepts, with a
view to the simultaneous control of
NOX, SO2, and particulate
emissions. This activity included
fundamental studies of parameters
affecting sulfur evolution and
retention by injected sorbents
under fuel-rich slagging conditions.
This Project Summary was
developed by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, to
announce key findings of the research
project that is fully documented in five
separate volumes of the same title
(see Project Report ordering
information at back).
Introduction
The objective of this program was to
evaluate the performance of the EPA
Distributed Mixing burner (DMB),
incorporating Babcock & Wilcox (B&W)
burner hardware, in a utility boiler. The
original plan to achieve this objective
involved four key elements:
1. A field test of the host boiler with
the original burners to establish the
"baseline" burner/boiler perform-
ance.
2. A test of the original, "baseline"
burner in the Large Watertube
Simulator (LWS) research furnace
to calibrate the furnace against the
corresponding host boiler.
3. Evaluation and optimization of a
prototype DMB with B&W
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components in the LWS to verify
performance prior to installation at
the host site.
4. Long-term field evaluation of the
DMB in the host boiler.
Progress on this plan was delayed
because of difficulties in finding a
suitable host boiler. Costs to fully retrofit
a utility boiler with DMBs escalated
beyond available funding. A revised
program scope addressed two distinct
issues. The major portion of the program
still focused on the evaluation of the DMB
for utility boiler application. The second
area of interest added to the scope of this
project was an evaluation of alternate
concepts for Iow-N0x emissions coupled
with high levels of particulate removal
and possible SOX control. These alternate
concepts considered fuel-rich, high-
temperature prechambers, such as
cyclone furnaces. The alternate concept
program was structured to: (1) compile
and synthesize existing data on coal-fired
precombustor systems; (2) conduct initial
pilot scale tests at 1 x 1Q6 Btu/hr (293
kW) to identify the key parameters
affecting NOX and SOX reduction
potential, and (3) a second phase of more
fundamental testing structured to
investigate a broader range of SOX
control issues in smaller, well-controlled
experiments to generate a more com-
plete set of basic precombustor design
data.
The evaluation of the DMB for utility
boiler application was restructured to
achieve the program objective without a
field installation. In the original program
plan, differences In performance with the
DMB were to be determined by direct
comparison to the original equipment
burners. The elimination of the field
installation precluded this comparison
and required dependence on research
furnace test results. As part of the revised
program, the performance of the
prototype DMB in the LWS research
facility had to be demonstrated to be
similar to the performance in a field
operating boiler.
The scope was further expanded with
an opportunity to directly participate in
full application of second generation low-
emission burners to an operating boiler.
The EPA demonstration of LIMB
(Limestone Injection Multistage Burner)
technology had the objective of reducing
both NOX and S02 emissions by 50%.
The NOX reduction was to be achieved
by retrofitting existing burners at Ohio
Edison's Edgewater Unit 4 boiler with
second generation Iow-N0x burners.
Because of the constraints at this boiler,
evaluation of three candidate B&W
burners prior to selection was essential.
The broad scope of this program can
be thus separated into four distinct parts:
(1) the evaluation of prototype DMBs for
application to utility boilers; (2) field tests
of baseline burners at two host boilers to
support the extrapolation of prototype
DMB performance to field applications;
(3) evaluation of three B&W second
generation Iow-N0x burners to be
selected for use in the EPA LIMB
demonstration; and (4) alternate concepts
for NOX and SOX control in
precombustors. Each of these represents
a distinct element of the program. The
final report is, therefore, organized to fully
address each element.
Volume l~Distributed Mixing Burner
Evaluation. Volume I presents the results
from the prototype DMB evaluations in
the LWS, the principal element to achieve
the original program objectives. This part
describes the methodology employed to
evaluate the DMBs without a field retrofit,
linking research furnace results to
operating boilers. The experimental
systems, including test burners, fuels, the
test facility itself, and testing procedures,
are fully detailed. Burner performance for
each test burner is discussed. The key to
interpreting the results is the link of the
LWS test results to operating utility
boilers achieved with tests of commercial
B&W burners in the LWS and field test
results of the same burner design in
utility boilers. This link allows extra-
polation of prototype DMB performance
from the LWS to the field. A summary of
sorbent injection trials for SO2 control is
also included in Volume I to broaden the
existing data base and experience with
LIMB technology.
Volume //--Second Generation Low-
NOX Burners. Volume II summarizes the
LWS trials of the three B&W Iow-N0x
burners being considered for the EPA
LIMB demonstration program at
Edgewater Station Unit 4. The three
burners were: the Dual Register burner
(DRB), Babcock-Hitachi NR burner
(HNR), and the B&W XCL burner. The
burners and each configuration tested are
described, along with the fuels and test
facility configuration used throughout
these tests. The optimization of the
various configurations of each basic
burner design is described with respect
to the key performance criteria of NOX
emissions, flame length, combustion
efficiency, and burner pressure drop. The
performance of each optimized
configuration is compared to the LIMB
demonstration site requirements and
recommendations for burner selection
are made. Finally, sorbent injection test
were conducted for a selectei
configuration of each burner design
These tests were performed to determim
any possible effect of burner design oi
SO2 capture potential with sorben
injection.
Volume 111--Field Evaluations. Volumi
III details the field tests performed ii
conjunction with the DMB evaluation. Thi
field tests were performed at two differen
utility boilers, generally similar in desig
and size except for the burne
equipment. Comanche Unit 2 of Coloradi
Public Service was equipped with B&V
Circular burners, the pre-NSPS (Ne\
Source Performance Standard) burne
design. The Wyodak Plant of Black Hill
Power was equipped with DRBs. Tes
results of emissions and boile
performance are presented for each uni
Key performance aspects from these tw
boilers are used in interpreting LWS test
of the Circular burner and the DRB.
Volume IV--Alternate Concepts. Pre
combustor studies for NOX and SO
control are described in Volume IV. Thi
work represents alternate concept
considered as a result of the program'
restructuring. Volume IV stresses th
fundamental design considerations fc
precombustor control of S02 emission
with a brief summary of pilot scale, 1
106 Btu/hr (293 kW) tests for NOX contra
The various experimental apparatus an
test procedures for this fundamental wor
are described. Results from entraine
flow sulfidation tests and slag sulfi
chemistry are fully detailed.
Volume V—Burner Evaluation Dai
Appendices. Volume V documents th
Quality Assurance program for the LW
tests of the DMB evaluation and th
Second Generation Low-NOx burne
selection. In addition, computer listings <
all valid data reported in Volumes I and
are included for reference.
Distributed Mixing Burner (DME
Evaluation
The objective of this program was 1
demonstrate the performance of the DM
on a multi-burner utility boiler. Th
involved integrating the DMB concei
with Babcock & Wilcox (B&W) burnt
components to produce a prototyp
burner meeting commercial standards.
the original program plan, th
demonstration was to include a full-sea
utility boiler retrofit with DMBs. Tr
effectiveness of the DMB was to t
determined by direct comparison with tt
original equipment burners in or
representative operating utility boile
-------
Difficulties in finding a host boiler to
participate in a demonstration retrofitting
existing burners with the new OMB
technology resulted in delays to the
overall program. These delays, in turn,
caused escalating costs for a utility boiler
retrofit with DMBs. Because of these
problems, the program was restructured
to achieve its objective without installing
the DMB in a utility boiler. The approach
taken was extensive testing of DMBs at
two scales and two B&W commercial
burner designs in the EPA Large
Watertube Simulator (LWS) coupled with
field tests at utility boilers equipped with
the two B&W commercial burners. This
approach provided data for burner
scaleup, performance characteristics of
the DMB compared to commercial
burners, and commercial burner per-
formance in utility boilers. With this data,
the expected performance of DMBs can
be extrapolated to utility boilers with
some confidence.
LWS Tests
In the original program plan,
differences in performance with the DMB
were to be determined by direct
comparison of the original equipment
burners. The elimination of the field
installation precluded this comparison
and required dependence on research
furnace test results. As part of the revised
program, the performance of the
prototype DMB in the LWS research
facility had to be demonstrated to be
similar to the performance in a field
operating boiler. This objective was
achieved by: (1) translating develop-
mental DMB design criteria into practical
prototype burners; (2) verifying and
optimizing the performance of the
prototype B&W DMBs in the LWS; (3)
evaluating the performance of two
commercial burners in both utility boilers
and the LWS; and (4) from that data
base, extrapolating the prototype DMB
performance to operating utility boilers.
Four different burners were tested:
• 120 x 106 Btu/hr (35 MW) Circular
burner
• 60 x 106 Btu/hr (17.6 MW) DRB
• 60 x 106 Btu/hr (17.6 MW)DMB
• 120 x 106 Btu/hr (35 MW) DMB
Two commercial B&W designs, the
pre-NSPS Circular burner and the low-
NOX DRB were tested in the LWS to
provide a basis on which to judge DMB
performance. This comparative evaluation
verified safe, efficient operation of the
prototype DMB, providing confidence for
field application. Limited sorbent injection
jsts evaluated the effect of burner
design on SO2 reduction potential for
both near-burner and upper-furnace
locations.
The full-scale 120 x 106 Btu/hr (35
MW) DMB was the key to this
demonstration program. The LWS test
furnace imposed severe constraints on
flame shape and size for a Iow-N0x
burner. Low-N0x burners, like the DMB,
rely on controlled, delayed mixing of the
fuel with air. This delayed mixing
generally produces a long flame which
may cause operational problems in a
boiler. Although equipped with adjustable
inner and outer secondary air registers as
well as tertiary air ports, the dominant
factor In determining ultimate per-
formance (NOX, flame length) was the
coal injector configuration. Iterative
modifications were made to the coal
Injector to yield the optimum per-
formance for the LWS. There was a
direct tradeoff between NOX emissions
and flame length.
The final design selected resulted in
unstaged flames about 16 ft (4.9 m) long.
At staged conditions (SRB 0.70)*, the
flame length increased to about 22 ft (6.7
m]. NOX emissions for the DMB at these
optimum settings at nominal full-load
conditions with a burner zone
stoichiometry of 0.75 and 20% excess air
were 282, 340, 298, and 273" ppm for
Utah, Illinois, Comanche, and Wyodak
coals, respectively. This performance
compares favorably with the two
commercial B&W burners tested, as seen
in Table 1.
The potential for S02 control combined
with NOX reduction was evaluated in a
series of sorbent injection trials. Six
injection locations were considered.
Three sorbents were used: Vicron 45-3
limestone, Colton hydrated lime, and a
limited number of tests with a pressure
hydrated dolomitic lime. Thermal
environment was the key factor
determining SO2 capture efficiency.
Upper furnace locations where gas
temperatures were about 2200°F
(1200°C) yielded the highest captures.
Near-burner injection, either with the coal
or through tertiary air ports, generally
gave the poorest SO2 capture. The
pressure hydrated dolomitic lime was the
most effective of the three sorbents on a
Ca/S molar ratio basis; however, the
advantage disappears when considered
*SRg Burner zone stoichiometry, fraction of
theoretical air
'All emission concentrations reported are
corrected to 0 percent 02 on a dry basis, except
where indicated.
on a mass addition basis because of the
additional magnesium component.
Field Tests
Field testing was conducted at two
boilers, one equipped with the Circular
burner and one with the DRB. The boilers
were selected by B&W to be comparable
in terms of age, capacity, coal
characteristics, and firing configuration.
The Circular burner was evaluated at the
Colorado Public Service Comanche
Generating Station, Unit 2 located in
Pueblo, Colorado. The DRB was tested at
the Wyodak Generating Station, Gillette,
Wyoming, owned by Pacific Power and
Light Company and the Black Hills Power
and Light Company. Testing was
conducted for 1 week at Comanche in
December 1984 and for 2 weeks at
Wyodak in February 1985. Both the
Comanche and Wyodak units have a
nominal maximum capacity (MCR) of 350
MWB (gross).
Both boilers fire subbituminous coal
and use a front and rear wall firing
configuration. The front and rear wall
burners at the Comanche boiler are
directly opposed with four rows of four
burners each. The front and rear burners
at Wyodak are offset to avoid flame
interactions and are arranged in five rows
of three burners each. The boilers have
comparable furnace cross-sectional
dimensions, but the Wyodak boiler has a
taller furnace to accommodate the five
burner rows. Thus, the Wyodak furnace
has a lower ratio of firing rate to cooled
surface area.
During testing, the boilers were
generally operated in a normal fashion by
the operators. Thus, the burner settings,
load, and excess air were controlled by
plant personnel. The overfire NOX ports
were closed during the day at the
Comanche boiler, and returned to their
normal open position of 18% at night.
Both the Circular boiler and the DRB
operated satisfactorily during the tests.
Exact flame lengths could not be
determined with the available observation
ports. Both burners showed a high
combustion efficiency, and large
imbalances of fuel or air distribution were
not observed.
Both boilers operated over a narrow
excess 02 range, 2.5 to 3.5% at
Comanche and 3.8 to 4.0% at Wyodak.
Thus, the data were not sufficient to
establish NOX emissions with excess Q2.
Figure 1 shows NOX emissions at the two
boilers as a function of load. Both
correlations show a similar slope, with
lower N02 emissions for the DRB at
Wyodak. Nominal NOX emissions with the
-------
Table 1. Comparison of Burner Performance in the LWS Firing Utah Coal (SRT=1.20)
DMB
Firing Rate (106 Btulhr)
(MW)
SRB
Furnace Exit Gas
Temperature
(°F)
(°C)
NOX (ppm @ 0% 02)
Flame Length (ft)
(m)
Full-Scale
120
(35.2)
0.70
1792
(978)
282
22
(6.7)
Half-Scale
60
(17.6)
0.70
(969)
350
18
(5.5)
UHB
Half-Scale
60
(17.6)
1.20
1776
(969)
390
18
(5.5)
circular
Full-Scale
120
(35.2)
1.20
1828
(998)
380
>22
(6.7)
800
700
600
500
300
200
100
MCR = 350 MWe (Gross)
(Wyodak and Comanche)
MCR
60 120 180 240
Load(MWe)
Figure 1. NOX emissions vs. boiler load.
300 360
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Circular burner at Comanche were 550
ppm at 0% O2[0.64 lb/106 Btu (0.29
kg/kJ)]. Full load emissions at Wyodak
with all mills in service were 395 ppm at
0% O2[0.46 lb/106 Btu (0.21 kg/kJ)].
Second Generation Low-NOx
Burner Evaluation
The initiation of the LIMB (Limestone
Injection Multistage Burner) technology
demonstration at the Ohio Edison
Edgewater Station, Unit 4, provided an
opportunity to broaden the relevance of
this project. The objective of this LIMB
program with respect to burner design
was to provide a commercial pulverized-
coal burner that demonstrates a reduction
in nitrogen oxide (NOX) emissions of at
least 50% relative to uncontrolled
performance of the original Babcock &
Wilcox (B&W) Circular burners.
The three B&W Iow-N0x burner
designs being considered-the DRB,
Babcock-Hitachi NOX Reducing (HNR)
burner, and the XCL burner-were tested
at full scale in the EPA Large Watertube
Simulator (LWS) to determine the
optimum design for use at the Edgewater
boiler as part of this study. Burners sized
at 78 x 106 Btu/hr (22.9 MW), the same
size as the Edgewater burners, were
tested in the LWS, minimizing scaleup
questions. By coincidence, the LWS has
a firing depth of 22 ft (6.7 m), essentially
the same as Edgewater Unit 4. Screening
tests of the three basic burner designs
were conducted firing Pittsburgh No. 8
coal, the coal to be used during the LIMB
demonstration, to determine optimum
operating conditions. In addition to
available burner adjustments, a number
of burner hardware components were
also evaluated to establish the optimum
burner design. Sorbent injection tests
were completed for a selected
configuration of each basic burner to
determine the effect of burner design on
S02 capture. Following the screening
tests of the three burners, selected XCL
burner configurations were characterized
with three additional, distinctly different
coals to broaden the application of this
new burner.
Optimization tests of the three basic
burner designs screened the available
burner adjustments as well as the various
burner component configurations. The
three basic components of each burner
(the coal injector, inner secondary air
zone, and outer secondary air zone) were
evaluated in these screening tests. The
results from these tests can be easily
eneralized for all three Iow-N0x burners
•vith respect to sensitivity of performance.
In each case, the coal injector was the
dominant factor that determined the key
performance characteristics of NOX,
flame length, and carbon burnout. Both
the design of the coal injector and the
available adjustments could produce up
to 67% reduction in NOX emissions. The
outer secondary air zone, the degree of
swirl, and the air flow rate through the
outer passage were second in
importance to burner performance. The
inner air zone parameters of swirl and air
flow rate generally had the least effect on
performance.
Consistent and recurring throughout
the screening tests of all three burners
was the close correlation of NOX
emissions with flame length. Data from
tests of the DRB, HNR burners, and the
initial screening tests of the XCL burner,
summarized in Figure 2, clearly shows
this correlation. At 20% excess and full
load conditions, these data indicate that,
for a flame less than the firing depth of
the Edgewater boiler, NOX emissions in
the range of about 300-400 ppm were
achieved by several burner con-
figurations. With flame length as the most
severe constraint at the Edgewater boiler,
only 8 of the 20 burner configurations
tested in this program and 5 Phase V
DRB configurations achieved flames less
than 22ft (6.7 m) long. These are listed in
Table 2.
From the numerous burner con-
figurations tested, two stand out as
suitable for application for the LIMB
demonstration. All configurations tested
met the requirements of a firing capacity
of 78 x 106 Btu/hr (22.9 MW) burner, a
throat diameter no greater than 35 in.
(88.9 mm), and mechanical reliability
meeting commercial standards. The
Edgewater boiler also imposed the
constraint on flame length, 22 ft (6.7 m),
and on maximum tolerable burner
pressure drop, about 5 in. (127 mm)
water gauge. In addition, the burners had
to produce a stable flame with low
emissions but high combustion eff-
iciency. The two configurations meeting
all those conditions were:
• XCL burner with 30° impeller in the
standard coal nozzle with appropriate
outer vane design.
• XCL burner with 20° impeller in an
expanded coal nozzle.
In addition to meeting all Edgewater
boiler requirements, the two impeller-
equipped XCL burner configurations offer
a very effective way to optimize
performance to suit the application, using
the adjustable coal impeller. For both
designs, flame length and NOX emissions
can be varied simply by moving the
impeller a matter of inches. The impeller
adjustment can thus be used to tune the
burner for maximum NOX reduction within
the constraints of available firing depth.
Alternate Concepts for SOX,
NOX, and Particulate Emissions
Control from a Fuel-Rich
Precombustor
The potential for simultaneous control
of ash, NOX, and SOX emissions from
coal-fired boilers and heaters by
combustion external to the furnace has
made precombustor development an
area of great interest and effort. A
precombustor burns coal in a chamber
outside the normal furnace region. An
example of a simple precombustor is
shown in Figure 3.
Aerodynamic separation and slag
drainage remove most of the coal mineral
matter before entry into the furnace. Also,
staged combustion and fuel reburning
have been shown to be an effective way
to control NOX emissions. It has been
proposed that the use of calcitic sorbent
or possibly other additives in a fuel-rich
precombustor can produce significant
reductions in overall SO2 emissions.
Successful control of all three pollutants
would allow coal users to circumvent
expensive exhaust stream cleanup
equipment and help avoid derating in oil
or gas retrofit applications.
The issue of sulfur capture under fuel-
rich conditions has been an area of
uncertainty and much recent interest. The
fuel-rich reactions of:
H2S + CaO-»CaS + H20 and
COS + CaO + CaS + C02
are theoretically more effective at
capturing gas-phase sulfur than the well
studied fuel-lean reaction:
SO2 + CaO + 1 /2 O2-*CaSO4,
from both a thermodynamic and kinetic
standpoint. However, at the time this
program was initiated, the operating
conditions which promote these fuel-rich
reactions had not been fully investigated.
In addition, the presence of a liquid slag
in the reactor was thought to be a
potential source of sulfur capture or
regeneration which required additional
research.
The program involved two phases: (I)
exploratory testing of a pilot-scale coal
precombustor [293 kW (1x106 Btu/ hr)] to
help identify critical operating parameters
for precombustor systems with NOX
control and the potential for sulfur control;
and (2) a more fundamental investigation
of factors affecting sulfur removal under
fuel-rich conditions.
-------
The pilot-scale testing indicated that
there was significant sulfur captured as
calcium sulfide (CaS) by suspended
sorbent particles in the fuel-rich
combustion zone of the precombustor.
However, there was evidence that sulfur
was released from the CaS when
exposed to a fuel-lean flame front. There
was also concern that sulfur in the slag
layer was evolving back into the gas
phase. A combination of high solids
carryover, complexities of sampling in the
pilot-scale precombustor, and a growing
number of fundamental questions
concerning fuel-rich sulfur capture led to
Phase 2, which is the main topic of the
alternate concepts report.
The objective of Phase 2 was to make
a detailed investigation of several key
elements in the fuel-rich sulfur capture
process, including: 1) the formation of
stable sulfides in the entrained flow
region of a precombustor using calcium-
based sorbents, 2) the evolution of sulfur
from coal in an entrained flow process,
and 3) the stability of sulfur in molten
slag layers.
This program focused on the area of
fuel-rich sulfur capture, since little more
than theoretical predictions and a few
uncertain tests results were available.
Several obstacles face the successful use
of calcitic sorbents in fuel-rich coal-fired
precombustors. The most important
issues were investigated in this program,
including: extent of entrained flow
sulfidation, the speciation of sulfur as it
evolves from coal under fuel-rich
conditions, the equilibrium solubility of
sulfur in molten slags, the impact of
fluxing additives on slag fluidity and
sulfur solubility, and the rate at which
sulfur regenerates from slags containing
a super-equilibrium level of sulfur.
The major conclusions from this
program are:
• The sulfidation reactions betweer
CaO and HgS or COS are fast and
under optimum conditions,car
capture most of the gas-phase sulfu
in a fuel-rich precombustor.
• The conditions which favor fuel-ricf
sulfur capture (deep sub
stoichiometric operation and mod
erate temperatures) can result it
poor carbon burnout and low sla<
fluidity.
• Typical molten coal ash and mixture:
of coal ash and CaO are incapable c
holding large amounts of sulfur in
coal precombustor environmen
when at equilibrium.
1000
900
800
700
g; 600
O1 500
o
0)
o*
400
300
200
100
(') 1ft = 0.30 m
4
4 * * f
A -
6
Nominal Conditions:
Fuel: Pittsburgh No. 8
Firing Rate: 78 * 106 Btulhr (22.9MW)
SRT = 1 20 (20% excess air)
Dual Register Burner
O Diffuser
A 75° Impeller
Q De-Nox Stabilizer
Q Flame Stabilizing Ring/Air
Separation Plate/Swirler
Babcock-Hitachi NOX Reducing Burner
O> Swirler
0 Diffuser
XCL
• Diffuser
A 30° Impeller
• De-NOx Stabilizer
£ Flame Stabilizing Ring
10 12 14 16 18
Observed Flame Length (ft*)
20
22
Figure 2. Correlation of NOX emissions with flame length.
-------
Coal ash/CaO slags quickly
desulfurize from super-equilibrium
levels of sulfur at typical
precombustor temperatures and gas
compositions, indicating that rapid
slag drainage designs are required.
Slag fluxing additives, such as
B203,can extend operating
conditions which will make fuel-rich
sulfur removal a possibility over a
wider range of coal types and
precombustor systems.
Table 2. Second Generation Low NOXBurners with Flames <22 ft (6.7m) Long [78* 106 Btu/hr (22.9 MW), SRr ,-1.20]
Burner dP, in. W.G.
Burner
Low-Velocity DRB
Phase V DRB
HNR
XCL
Configuration
75" Impeller
Diffuser
Venturi
Diffuser, ASP
Diffuser, FSR
Diffuser, FSR, ASP
Swirler
Diffuser
DNS
30"lmpeller,
Standard Nozzle
30"lmpeller,
Expanded Nozzle
20" Impeller,
Expanded Nozzle
30" Impeller,
Standard Nozzle,
Fixed Outer Vanes
NO, <@ 0% O-,, ppm
708
372
350
326
292
328
348
289
288
374
546
338
420
Flame Lenath, ft (m)
18
(5.5)
20-21(6.1-6.4)
20-21(6.1-6.4)
22(6.7)
22(6.7)
22(6.7)
18-20(5.5-6.1)
20(6.1)
20(6. 1)
20-22(6.1-6.7)
19-20(5.8-6.1)
21(6.4)
21-22(6.4-6.7)
Flv Ash Carbon, wt%
7.28
6.12
6.45
3.20
6.96
5.16
N/A
3.34
N/A
4.42
1.36
4.92'
3.40
(mm W.G.)
6.0(152)
10.8(274)
11.0(279)
6.4(162)
10.5(267)
11.0(279)
7.20(183)
7.50(190)
8.20(208)
3.30(84)
4.30(109)
4.90(124)
4.60(117)
"Data for SRT ,1.16
Primary
Air
Coal-
Boiler
Furnace Wall
Fuel-Rich (SRrf
Fuel-Lean (SR2)
Figure 3. Common cyclonic precombustor in staged combustion configuration attached to boiler furnace wall.
-------
A. Abele, J. LaFond, J. Cole, G. Kindt, W. Li, E. Moller, R. Payne, and J. Reese
are with Energy and Environmental Research Corp., Irvine, CA 92718.
P. Jeff Chappell is the EPA Project Officer (see below).
The complete five volumes, entitled "Field Evaluation of Low-Emission Coal
Burner Technology on Utility Boilers:"
"Volume I. Distributed Mixing Burner Evaluation," (Order No. PB90-155 680/AS;
Cost: $23.00)
'Volume II. Second Generation Low-NOx Burners;" (Order No. PB90-155
698/AS; Cost: $23.00)
'Volume III. Field Evaluations;" (Order No. PB90-155 7051 AS; Cost: $23.00)
'Volume IV. Alternate Concepts for SOX, NOX, and Particulate Emissions Control
from a Fuel-Rich Precombustor;" (Order No. PB90-155 714!AS; Cost:
$23.00)
Volume V. Burner Evaluation Data Appendices," (Order No. PB90-155 7221 AS
Cost: 23.00, subject to change) 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
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-89/015
UaOFFSCIALMAit"
i-
0 ,3 5 =C
'»
000085033 PS
U S EN VIS PROTECTION AGENCY
REGION 5 LIBRABT
230 S DEARBORN STREET
CHICAGO IL 60604
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