United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-84~024b Apr. 1984
&ERt\ Project Summary
Evaluation of Low Emission Coal
Burner Technology on Industrial
Boilers: Second Annual Report
(1980)
B.A. Folsom, L.P. Nelson, A.R. Abele,
J.L. Reese, and J. Vatsky
This report summarizes the second
year's effort under EPA Contract
68-02-3127. The objective of the program
is to conduct field evaluations of the
distributed mixing burner (DMB) on two
industrial size boilers. The DMB concept
provides for controlled mixing of coal
with combustion air to minimize NOX
emissions, while maintaining an overall
oxidizing environment in the furnace to
minimize slagging and corrosion. Major
accomplishments in 1980 included
preparation of a measurements protocol
which specifies all measurements to be
made during the program, baseline tests
of the initial host boiler, and initial tests
of a prototype DMB designed for the
host boiler.
This Project Summary was developed
by £PA's Industrial Environmental Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
For the last several years, Energy and En-
vironmental Research Corporation has been
working with the EPA to develop a Iow-N0x
pulverized-coal burner. This distributed mix-
ing burner (DMB) controls the mixing of coal
with combustion air to minimize NOX emis-
sions, while maintaining an overall oxidizing
environment in the furnace to minimize slag-
ging, fouling, and corrosion. DMBs have
been tested at firing rates up to about 100
x 10* Btu/hr* in single- and four-burner
arrays in two research furnaces. The tests
covered wide ranges of burner adjustments
and operating conditions. When coal was
fired in the research furnaces under optimum
conditions, NOX levels less than 0.15 lb/10*
Btu were obtained. However, the DMB per-
formance has not been evaluated in a com-
mercially operated steam generator. The
objective of this program is to evaluate the
DMB concept on two commercially operated
industrial size boilers. The goal is to attain
NOX emission levels less than 0.2 lb/101 Btu
without adverse effects on boiler operabili-
ty and durability, thermal efficiency, and the
emission of other pollutants. The field evalu-
ations involve: 1) translation of development
burner test data into practical prototype
DMBs, 2) verification of prototype burner
performance through testing in a research
furnace, 3) construction and installation of
these burners in field boilers and evaluation
of their performance under typical operating
conditions, 4) documentation of the results,
and 5) input to the parallel utility field evalua-
tion (EPA Contract 68-02-3130). The pro-
gram is being conducted in nine tasks. Table
1 lists the tasks and progress achieved.
In Task 1, all of the basic elements of the
program were planned, including boiler se-
lection, burner design, and establishment of
a measurements plan. Two host site boilers
were selected and negotiations with the
operators completed so that a firm schedule
for the remaining aspects of the study could
Readers mofe famliar with metric unto may use the con-
version factors at the back of this Summary.
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Table 1. Program Status Summary
Task
Program
First
Field Evaluation
Second
Field Evaluation
Task 1 - Program Definition
Host Boiler Selection
Burner Engineering Design
Analytical Measurements Plan
Overall Program Plan
Task 2 - Prototype Construction and
Testing
Burner and Support Equipment
Construction
Prototype Burner Tests
Host Burner Tests
Task 3 - Boiler Baseline Evaluation
Task 4 - Burner Installation
Task 5 - Performance Evaluation
Task 6 - Industry Coordination
Task 7 - Restoration
Task 8 - Data Analysis
Task 9 - Guideline Manual
Boiler Inventory
Evaluated
Design Criteria
Identified
Measurements Protocol
Completed
Cold Flow Test Facility
Designed and Under
Construction
Two Panel Meetings
Were Held
Selected
Prototype DMB
Designed
Sampling System
Constructed and
Installed
Initial Testing
Completed
Initial Testing
Completed
Initial Testing
Completed
Scheduled for
Spring, 1981
In Progress
Selected
Sampling System
Designed and Under
Construction
Scheduled for 1981
Scheduled for Spring,
1982
be established. The final burner designs were
established when the boilers were selected.
Prototype burners (including all controls)
were then constructed, installed in the large
watertube simulator (LWS) furnace, and
evaluated using several coals as part of Task
2. In addition, the commercial burners used
in the host site boilers were also evaluated
in the LWS so that a one-to-one comparison
of operating characteristics could be deter-
mined and the potential problems identified.
The Task 3 boiler baseline evaluations
of the host units establish normal operat-
ing characteristics and the potential for
reducing NO, emissions by off-design
point operation. After baseline character-
ization, the lowNOx coal burners and all
support systems are installed on each
host boiler in Task 4. The burner and
burner systems then undergo checkout
testing to ensure their ability to perform
similarly to the original burners.
At this point in the program, the low emis-
sion burner systems are ready for extensive
evaluation in Task 5. The retrofit boilers are
run over a sufficient range of operating con-
ditions consistent with the operational steam
requirements to define the multiburner op-
timization of emissions so that the operating
point can be established. Long-term evalua-
tions (18 months) are then conducted with
the boiler operating under a normal duty
cycle. After this task, the boiler/burner
system is inspected and the condition of all
systems documented. Task 7 involves the
restoration of the boilers to their original
state.
The remaining Tasks 6 and 8 are accom-
plished concurrent with all of the other tasks.
Lastly, the final report. Task 9, involves in-
tegrating the overall effort into a concise
summary illustrating the application of the
technology to a wide variety of coal-fired in-
dustrial boilers.
The progress on each task listed in Table
1 was achieved over the last 2 years. The
major accomplishments this year included
preparation of the measurements protocol,
baseline tests at the initial host boiler, and
initial prototype burner tests. These items are
discussed here.
Note that the prototype burner design
discussed in this report is the initial flexible
design based on the results of previous DMB
development efforts and Foster Wheeler
burner components. During tests of the in-
dustrial prototype burner in the LWS, some
design parameters were changed consid-
erably, including the incorporation of some
proprietary Foster Wheeler components and
parameter values. Results of this LWS
testing and the changes in the burner
designs are documented in subsequent an-
nual reports.
Measurements Protocol
The measurements made during this field
evaluation program will quantify the reduc-
tions in NOX emissions achieved by the EPA
low emissions coal burner and will identify
any potential problems in the application of
this technology to field operating boilers. The
accuracy, completeness, and appropriate-
ness of the measurements are, thus, key to
the program's success. A measurements
protocol (or measurements plan) has been
prepared to ensure that the program goals
are achieved; i.e., the evaluation of the EPA
low emission coal burner technology on field
operating boilers. Specifically, it identifies the
parameters to be measured, measurement
methods, calibration procedures, measure-
ment frequency, and data quality con-
trol/assurance procedures. The key aspects
of the measurements protocol are summa-
rized below.
-------
The measurements in these programs will
be associated with burner tests in the
research furnace at EER (LWS) and the field
boilers. The burner tests will be developmen-
tal. The measurements protocol for the LWS
tests includes measurement of key test con-
ditions and test outputs with accuracy and
repeatability sufficient to allow the relation-
ship between burner adjustments and burner
performance to be determined. The burner
tests in the field operating boilers will con-
stitute the actual field evaluations of the EPA
low emissions burner concept. The mea-
surements protocol for the field tests pro-
vides more detailed and complete
measurement methods; where possible, all
measurements are referenced to absolute or
NBS standards.
The measurements have been organized
into categories of increasing complexity: 1)
standard measurement format, 2) detailed
measurement format, and 3) effluent stream
analysis. In addition, corrosion measure-
ments will be conducted as part of the field
tests.
Standard Measurement Format
This minimum set of measurements will
be applied to all LWS and field tests. It in-
cludes measurement of the test inputs nec-
essary to specify operating conditions, as
well as routine measurement of output pa-
rameters. Table 2 lists the parameters and
measurement methods for the field tests.
The measurements for the LWS tests are
similar, except that the measurement meth-
ods are simplified. Where practical, con-
tinuous measurement methods have been
selected so that the duration of specific tests
will be limited by the dynamics of the
burner/furnace systems rather than the
maximum data acquisition rate. For exam-
ple, gas-phase species in the combustion
products will be measured with continuous
gas analyzers. Where burner performance is
to be evaluated at specific test conditions,
the entire standard measurement format will
be applied. A portion of the standard
measurement format (02, CO, and NOX
measurement) will be applied continuously
during the long-term field tests.
Detailed Measurement Format
This includes all measurements in the stan-
dard measurement format, plus intermittent
measurement of certain output parameters.
Table 3 lists the parameters and measure-
ment methods for the field tests. Again, the
format for the LWS tests is somewhat sim-
pler. The detailed measurement format will
be applied to selected test conditions to more
fully characterize burner performance. Dur-
ing the LWS tests, the detailed measurement
format will be applied to the original equip-
ment burner tests and the tests of the op-
timized low emission burner. The test
conditions will be selected to cover the range
of operation of the field boilers so that com-
plete maps of burner performance will be ob-
tained. During the field tests, the detailed
measurement format will be applied similarly
to map burner/boiler performance. The de-
tailed measurement format includes manual
measurements of several parameters, in-
cluding paniculate mass, particulate size
distribution, and SO3. These measurements
are time-consuming and may limit the rate
of testing.
Effluent Stream Analysis
This, the most complex measurement for-
mat, will be applied to a few test conditions
of special significance. It is based on an EPA
Level 1 Environmental Assessment including
Table 2. Standard Measurement Format Summary (Field)
Test Conditions
bioassay, as well as certain other emission
measurements. As a minimum, the effluent
stream analysis will be applied to the full-load
operating conditions of the original equip-
ment burners and low-emission burners at
each field evaluation site.
Corrosion will be measured to ensure that
the low emission burners do not contribute
to furnace wall corrosion. These measure-
ments will be conducted only in the field
boilers, since the LWS tests are too brief to
accurately assess corrosion rates. Corrosion
panels will be installed before the low emis-
sion burners are installed so that data can
be obtained with the original equipment
burners. While installing the low emission
burners, tube thickness will be measured at
several locations to establish baseline corro-
sion rates. After the long-term tests of the
low emission burners, the corrosion panels
will be removed and the tube thicknesses will
be remeasured, to provide a direct com-
parison of the corrosion rates for the two
burners.
During the LWS tests, data quality will be
maintained by following the test procedures
in the protocol. However, the increased im-
portance of the field tests requires a data
quality control plan. To ensure that the emis-
sion measurements are accurate, EPA meth-
ods will be used as the primary measurement
methods or as reference methods. In addi-
tion, the continuous monitoring system will
be constructed, calibrated, verified, and
operated according to EPA Performance
Specifications 2 and 3. The field tests will
also be subjected to a quality assurance audit
by an independent EPA contractor.
The measurements protocol is a working
document. It is recognized that, in a 4-year
program, there are likely to be advances in
Test Outputs
Parameter
Furnace Design
Burner Design
Burner Adjustments
Registers
Dampers
Others
Fuel
Composition
Flow Rate
Combustion Air
Flow Rate
Temperature
Distribution
Measurement Method
Direct Measurement
Obtain Sample (analyze
under detailed format)
Boiler Instrumentation
Boiler Instrumentation
Boiler Instrumentation
Internal Flowmeters or
Boiler Instrumentation
Parameters Measurement Method
Flame Characteristics
Length
Width
Standoff
Stability
Gas Phase Species
02
NO/NO,
CO
CO2
Direct Observation
and/or Color Video
Flame Scanner
Continuous Analyzers
Other
Thermal Performance Boiler Instrumentation
Smoke Direct Observation
Windbox Pressure Boiler Instrumentation
Burner Temperatures Thermocouples
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Table 3. Detailed Measurement Format Summary (Field)
Test Conditions
Test Outputs
Parameter
Measurement Method
Parameters
Measurement Method
Fuel
Composition
ASTM Methods (ultimate
and proximate)
EER Laboratory Methods
(ultimate)
Particulate
Total mass
Composition
EPA Method 5
EER Laboratory Methods
(ultimate)
Size Distribution ASME Method Size Distribution
Carbon Balance
CO, C02
Hydrocarbons
Particulate
Bottom Ash
Coal
Sulfur Balance
SO2
S03
Particulate
Bottom Ash
Coal
Thermal Balance
Gas Concentrations in
the Furnace
Andersen Cascade Impactor
Standard Measurement Format
Hot F.I.D.
Same as Above
Grab Sample and EER Laboratory
Ultimate Analysis
Same as at left
Continuous Monitor and/or
EPA Method 6
EPA Method 8 and Controlled
Condensation
Same as Above
Same as Above
Same as at Left
ASME Method
Continuous Monitors
the state-of-the-art; therefore, the protocol
will be updated throughout the program.
These revisions will come about because of
data generated In the program and from data
obtained from such other sources as en-
vironmental impact studies and relevant
development programs.
Boiler Baseline Evaluation
The initial host boiler is Pearl Station Unit
1, operated by Western Illinois Power Cor-
poration (WIPCO). This small utility boiler is
representative of the design used for many
larger industrial boilers. It has four Foster
Wheeler intervene burners (pre-NSPS), rated
at 70x10" Btu/hr each. These burners, ar-
ranged two high by two wide on the front
wall, currently fire a high-volatile, high-sulfur
bituminous coal.
This unit was tested to establish baseline
performance before installing the low NOX
burners. The tests were conducted in four
series: burner modification test, 30-day
baseline test, thermal efficiency test, and ef-
fluent stream analysis.
The burner modification test involved
evaluating boiler performance at conditions
spanning the full range of operation. Rela-
tionships between the operating parameters
(load, excess air, and burner settings) and
performance were evaluated. In addition, the
potential for NO reduction by off-design
point operation, burners out of service, etc.,
was determined. The 30-day baseline test in-
volved monitoring burner/boiler perfor-
mance continuously over a 30-day period.
Boiler load and operating conditions were
selected by boiler operators as determined
by steam demand and previous experience.
This test was conducted immediately after
the burner modification test. Over the 30-day
period, the boiler operated at full load most
of the time. The emissions were comparable
to those measured at full load during the
burner modification test. The thermal effi-
ciency tests included measurement of the
distribution of heat absorption among the
various components as well as assessment
of overall thermal performance. Results of
the burner modification test are summarized
below. Data analysis for the other series is
still in progress.
The maximum continuous rating (MCR)
for the boiler is 20.0 MW. This corresponds
to a firing rate of 70x10* Btu/hr for each
burner. The design point excess air is 18 per-
cent, resulting in 3.3 percent 02 in the dry
combustion products. The boiler is normally
base-loaded and operates at this condition
for extended periods.
The flames from all four burners stabilized
close to the throat exit (within about 2 in.).
This is similar to the flame shape observed
during the tests of a similar burner in the
LWS. The WIPCO furnace was filled with
luminous combustion products, and it was
difficult to delineate flame boundaries. The
flames were definitely shorter than the fur-
nace depth (no rear wall flame impinge-
ment); however, they were not symmetrical
in the furnace. The flames on one side of the
furnace brushed (or rolled) along the side
wall, while those on the other side remained
well clear of the wall. Measurements of fur-
nace gases along the side walls confirmed
that reducing conditions (zero 02 and high
CO) existed in the areas where the flame was
observed to contact the furnace wall. Mea-
surements of the same gases at 12 probe
locations upstream of the air heater resulted
in essentially uniform results. Thus, varia-
tions in gas concentrations exiting the burner
zone are effectively smoothed out in the
upper furnace and/or convective pass. Reg-
ister adjustments were unsuccessful in pro-
ducing symmetrical flames. Foster Wheeler
has advised that this condition is unusual and
is investigating the problem.
Gas-phase concentrations measured up-
stream of the air heater at the MCR design
point were:
Concentration
Species Dry, 0% 02
02
NO
CO
C02
S02
HC
~ i i *
3.42% (as measured)
829 ppm
41 ppm
18.0%
2964 ppm
1 ppm
These results are the average of four tests.
The 02 concentration corresponds to 18.7
percent excess air, and the load averaged
20.5 MW. These are essentially the design
point conditions. Carbon and sulfur balances
based on the typical coal analysis result in
18.2 percent CO2 and 3200 ppm S02 for full
4
-------
conversion. Thus, the C02 and S02 concen-
trations are reasonable. The low CO and HC
concentrations are comparable to those
observed on other Foster Wheeler boilers of
similar design (CO emissions are typically
reported as "less than 50 ppm"). The NOX
emissions are somewhat higher than ex-
pected for boilers of this type. Foster
Wheeler had previously estimated 700 ppm
(600 ppm <§> 3% 02).
Burner/boiler performance was measured
over a range of excess air at full load (MCR).
The NOX results are shown in Figure 1. NOX
is observed to decrease with excess 02 as
expected. The minimum excess 02 (2.5 per-
cent) was specified by the WIPCO manage-
ment. Based on their experience, the flames
may become unstable at lower 02 levels.
However, this was not observed during the
current tests. Over the range of excess air,
CO and hydrocarbon (HC) emissions re-
mained the same as the design point. With
all four burners in service, the boiler could
be operated over a 13 to 21 MW range. The
upper end of the range was based on steam-
side limitations. Previous attempts to exceed
21 MW resulted in a loss of steam pressure
in the accumulator. The lower end of the
range was based on flame stability problems
which have been encountered at lower
loads. The reason for the instability has not
been determined. The instability may be due
to the inability of the oversize coal feeders
to operate at low feed rates. Another pos-
sibility is that the flame scanning system was
improperly adjusted, resulting in a loss-of-
flame indication.
The effect of load on NOX emissions with
all burners in service is shown in Figure 2.
1000
900
800
I
c)
0 700
O 600
500
O
02 = 3.3 ± 0.3%
Reg., Core - Baseline
13 14 15 16 17
Load.MW[e]
18
19
20
21
Figure 2. Effect of load.
The load curve is quite flat with NOX
decreasing by about 50 ppm as the load is
reduced from 100 to 75 percent of MCR.
There was no significant change in CO or HC
emissions over this range. CO and HC emis-
sions were always less than 30 and 3 ppm,
respectively.
The WIPCO boiler could not be operated
with one mill (two burners) in service without
supplementary oil firing for flame stability.
Attempts to shut off the supplementary oil
firing with two burners in service caused the
;ooo
900
800
O 700
o
600
500
Load = 20.3 ± 0.3 MW(e)
Reg., Core = Baseline
J_
o ; 2 3
Excess Oz, %
Figure 1. Effect of excess air variation at MCR.
flames to lift off the burners, resulting in a
loss-of-flame indication on the flame scan-
ning system. The flames might have stabi-
lized out of range of the scanning system,
but this was not confirmed due to the limited
duration of the tests. Foster Wheeler has ad-
vised that this is not typical of normal opera-
tion. The burners normally have a 2.5/1
turndown range and operate stably with
some burners out of service.
Prototype Burner Tests
The DMB concept involves staging the
combustion process to minimize NOX emis-
sions while maintaining an overall oxidizing
atmosphere in the furnace to avoid furnace
slagging and corrosion. NOX production
from fuel nitrogen compounds is minimized
by driving a majority of the compounds into
the gas phase under fuel-rich conditions and
providing a stoichiometry/temperature his-
tory which maximizes the decay of the
evolved nitrogen compounds to N2. Thermal
NOX production is also minimized by en-
thalpy loss from the fuel-rich zone which
reduces peak temperatures.
Figure 3 shows the DMB concept sche-
matically. Staging is achieved by arranging
the components for three zone combustion.
In the first zone, pulverized coal (transported
by the primary air) combines with the inner
secondary air to form a very fuel-rich (30 to
50 percent theoretical air) recirculation zone
which provides flame stability. The coal
devolatilizes and fuel nitrogen compounds
are released to the gas phase. Outer secon-
-------
Tertiary Air
Outer
Secondary Air
Inner
Secondary Air
X
Coal and _
Primary Air
Very Fuel Rich
Zone (A verage
Stoichiometry 40%)
Progressive Air Addition Zone
(Overall Stoichiometry 70%)
Final Air Addition Zone for Burnout
(Overall Stoichiometry 120%j
Figure 3. DMB concept.
dary air is added in the second burner zone
where Stoichiometry increases to about 70
percent theoretical air. This is the optimum
range for reduction of bound nitrogen com-
pounds to N2. Air to complete the combus-
tion process is supplied through tertiary ports
outside the burner throat. This allows sub-
stantial residence time in the burner zone for
decay of bound nitrogen compounds to N2
and radiative heat transfer to reduce peak
temperatures. The tertiary ports surrounding
the burner throat provide an overall oxidiz-
ing atmosphere in the burner zone.
A prototype DMB was designed to meet
the requirements of the initial host boiler.
The design involved integrating DMB design
parameters (based on previous tests), the
characteristics of the host boiler, and Foster
Wheeler burner components. Figure 4 shows
the central portion of the burner without the
tertiary air ports.
The prototype burner is being tested in the
LWS to optimize performance prior to install-
ing field operable burners in the host boiler.
The tests are being conducted in four
phases:
Flow Characteristics This includes
cold flow measurements of velocity and
swirl in the burner exit and calibration
of the air flow rates through the burner
passages as functions of pressure drops.
Unstaged Tests The burner is being
tested unstaged to verify that field per-
formance will be satisfactory if a prob-
lem should develop with the tertiary air
port system during field operation.
Staged Tests This is the major test
series: burner performance is evaluated
at the design operating point.
Performance Optimization/Verification
This includes adjusting the burner for
optimum balance of flame stability, ef-
ficiency, and emissions.
The flow characterization tests have been
completed. The velocities and swirl in the
burner exit were measured as a function of
burner settings. This information will be used
to identify the aerodynamic conditions which
optimize overall burner performance so that
improved DMBs can be designed for future
applications. Comparison with test results
Core Air
/Valve
f
from an intervene burner, which was also
tested, shows that the pressure drop across
the DMB is consistently lower. (Thus fan
capacity in the host boiler should be ade-
quate for the DMB.)
The initial combustion tests were con-
ducted in a research furnace without refrac-
tory insulation. Typical test results are shown
in Figure 5. Both unstaged and staged test
results are shown at full load. For unstaged
operation, the burner zone Stoichiometry is
equal to the overall Stoichiometry. NO emis-
sions were sensitive to excess air and were
nominally 320 ppm at 120 percent theoretical
air (T.A.), a typical field burner operating
condition. The CO emissions were unaf-
fected by excess air down to about 110 per-
cent T.A., where they rose sharply. This
unstaged behavior is typical of the perfor-
mance of many burners operating in field
boilers. However, the CO emissions are
about a factor of four higher than typical field
levels. This is probably a consequence of the
lack of insulation in the research furnace, as
discussed below.
A brief series of staged tests were con-
ducted with the overall excess air at 130 per-
cent T.A. As the degree of staging was
increased (burner zone Stoichiometry de-
creased), the NO emissions decreased as ex-
pected. The dotted line in Figure 5 is an
extrapolation to the staged design point. CO
emissions increased substantially as trie
degree of staging increased. Again, this is
believed to be a consequence of the research
Perforated Plate
Air Hoods
Removable
Nozzle
Rings
Firing
Face
Telescoping
' Inner Nozzle
Ignitor
Coal Inlet
Inner
Register
Outer
Register
Cast Refractory
Exit
Figure 4. Prototype DMB based on Foster Wheeler design (tertiary ports not shown).
-------
Load- 80 x 10*Bw/hr
600
500
400
300
2OO
700
I I I I I I
T.A. = Theoretical Air
Staged
130% T.A.
~ Staged
Design Point
118% T.A.
Unstaged
I I I I I I 1 I I 1
600
500
£400
Q
O
&300
g 200
700
II I I I II
T.A. = Theoretical Air
Staged
'130% T.A.
(
^-Unstaged
I I I I I I I I I I
50
100 150 50
Burner Zone Stoichiometry, 9
700
150
T.A.
Figure 5. Prototype burner performance in L WS (staged).
furnace design which was considerably
"colder" than field operating boilers.
Following these tests, the research fur-
nace was rebuilt. The new furnace was par-
tially insulated with refractory to provide a
thermal environment similar to field oper-
ting boilers. Figure 6 shows the results of
taged tests repeated in the new test facil-
ity. These tests were conducted at lower ex-
cess air, and the NO emissions are essentially
the same as the extrapolation based on the
initial data. However, CO emissions are
much lower, in the same range as field
operating boilers. This confirms that the high
CO emissions measured in the initial furnace
were due to research furnace design and did
not indicate burner performance which
would be measured in the field.
The minimum burner zone Stoichiometry
tested, 85 percent T.A., was the burner
stability limit. Increasing the degree of stag-
ing beyond this point resulted in flame de-
tachment. The minimum NO emissions at
the stability limit were 185 ppm, correspond-
ing to about 0.21 lb/106 Btu, close to the pro-
ject goal. Extrapolating the NO emissions to
the design point (70 percent T.A.) indicates
approximately 100 ppm. During subsequent
test series, burner parameters will be ad-
justed to increase stability at low burner zone
Stoichiometry.
The difference in thermal environment in
the old and new LWS provides additional in-
sight into the potential performance of the
DMB in a field operating boiler. Foster
Wheeler has found that NOX emissions from
their commercial firing equipment can be
related with the heat release per cooled
face area in the lower portion of the fur-
nace. Figure 7 shows Foster Wheeler's cor-
relation for the pre-NSPS intervene burner.
Data for the prototype DMB (extrapolated
to the design point) are also shown. Note
that the heat release per cooled surface area
(BZLR) for the new LWS is slightly less than
for the initial field boiler (WIPCO). The line
drawn through the prototype DMB data has
the same shape as the correlations for the
intervene burner and suggests that NOX
emissions from the field evaluation will be
slightly higher than the prototype burner test
700
I
600
500
400
300
© 200
700
T.A. = Theoretical Air
Old LWS
Load = 80x10* Btu/hr
0 - 130% T.A.
Extrapolation
of Old LWS Data
to Design Point
results. Of course, this correlation does not
account for the differences in the furnace
geometry and flame-to-flame interactions in
the field evaluation boiler.
As discussed above, the prototype DMB
tests, involving no optimization of burner
geometry or adjustments, resulted in unac-
ceptable flame stability at the design op-
erating point. Therefore, these low NO levels
can only be achieved in the field if the burner
can be modified to improve stability. How-
ever, NO emissions in the range of 0.2 lb/106
Btu appear feasible with the current design.
Future Efforts
The schedule for the remainder of the pro-
gram depends on the schedule for installing
the DMBs in the field evaluation boilers. Both
boilers operate continuously except for brief
maintenance outages once or twice a year.
The outages are scheduled during periods of
low power demand (spring and fall) when the
utilities are able to purchase replacement
power from interconnected power plants. To
minimize problems for the field boiler
owners/operators, the DMBs must be in-
stalled during the scheduled outages. Con-
sidering the overall aspects of the program
and the outage schedules, the earliest possi-
ble dates for installing the DMBs are: initial
field evaluation (WIPCO), 3/15/81; and sec-
ond field evaluation, 3/15/82.
Based on the prototype DMB test results,
additional testing in the LWS will be required
to identify the burner parameters and set-
tings which optimize performance and to
verify burner operation over the required
700
- 600
°f
New LWS
Load = 69-78 x 10* Btu/hr
0= 118-126% T.A.
I I I I
J300
200
700
I I I
T.A. = Theoretical Air
e,
I
O
I
60 70
80
90
100 110
60
70
80
90
100 110
Burner Zone Stoichiometry, % T.A.
Figure 6. Comparison of staged prototype burner performance in old and new L WS.
-------
1.2
1.1
1.0
0.9
I ^
? 0-7
S 0.6
5 o.s
0.4
0.3
0.2
0.1
Foster Wheeler.
Intervene Burner
in Single-Wall-^
Fired Field
Boilers
WIPCO
l
.DMB Prototype (LWS)
100 200 300
BZLR. 103Btu/hr-ft"
400
Figure 7. Prototype burner tests in the old
and newL WS: comparison with
Foster Wheeler NOiCorrelation.
range. Unfortunately, the time available prior
to the spring burner installation date will be
insufficient to incorporate the test results in
the field operable burner design and fabricate
four burners. Thus, this approach requires
the burner design to be established and
fabrication to be started based on current
test data. Subsequent prototype burner test
results would then be used to verify that the
burner design is satisfactory. This is a high
risk approach because it is possible that the
prototype test results may determine that the
burner design must be modified.
An alternate approach would be to incor-
porate the Foster Wheeler proprietary burner
criteria into the prototype OMB. Burners
designed according to these criteria have
already been demonstrated to be stable over
the required operating range. They could be
installed in the field boiler and operated
unstaged without additional prototype
burner testing. However, satisfactory staged
operation would need to be verified. This ap-
proach would ensure that the low NOX
burners are installed as early as possible and
would maximize the probability of success
through the use of proven commercial hard-
ware. Approval to proceed with this ap-
proach has been received from the Project
Officer.
The second demonstration has been
scheduled so that results from the initial
demonstration can be evaluated prior to
freezing the burner design. The burner de-
sign for the second field evaluation will be
based on the prototype burner design re-
cently tested in the LWS.
Conversion Factors
Readers more familiar with metric units
may use the following factors to convert
nonmetric units used in this Summary to
their metric equivalents:
Nonmetric Times Equals metric
Btu/hr
Btu/hr-ft2
lb/106 Btu
2.93
11.35
430
W,
kJ/hr-m2
ng/J
B. Folsom. L Nelson, A. Abele, J. Reese, and J. Vatsky are with Energy and
Environmental Research Corp., Irvine, CA 92714.
G. Blair Martin is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Low Emission Coal Burner Technology
on Industrial Boilers: Second Annual Report (1980)," (Order No. PB 84-159
227; Cost: $14.50, 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:
Industrial Environmental 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
US. GOVERNMENT PRINTING OFFICE: 1984-759-102/917
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