United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/012 May 1986
c/EPA Project Summary
Environmental Assessment of a
Coal/Water Slurry Fired
Industrial Boiler
D. Van Buren and L. R. Waterland
This report describes emission results
from field testing of an industrial boiler
retrofitted to fire a coal/water slurry
(CWS). Emission measurements perform-
ed included continuous monitoring of flue
gas emissions; source assessment sampl-
ing system (SASS) sampling of the flue
gas, with subsequent laboratory analysis
of samples to obtain total flue gas organics
in two boiling point ranges, compound cat-
egory information within these ranges,
specific quantitation of the semivolatile
organic priority pollutants, and flue gas
concentrations of 73 trace elements; EPA
Method 5 sampling for paniculate; EPA
Method 8 sampling for S02 and SO3
emissions; volatile organic sampling train
(VOST) testing for volatile organic priority
pollutant emissions; gas grab sampling for
onsite C1 to C6 hydrocarbons emission
measurements; gas grab sampling for
N20 emissions measurements; and grab
sampling of the CWS fuel for inorganic
composition determination.
NOX, SO2, SO3, CO, and total unburned
hydrocarbon (TUHC) emissions averaged
510,450, 2.6, 285, and Ippm (corrected
to 3 percent O2), respectively, during the
1 day test. Paniculate emissions, at 4.3
g/dscm, were high, although expectedly
so since the unit was not equipped with
a particle control device. Emitted particle
size distribution was heavily weighted to
coarse paniculate. Over half the emitted
mass was greater than 10 pirn diameter;
over 90 percent, greater than 3 ^m. Com-
bustibles loss in the paniculate was high;
the composite paniculate was over 40 per-
cent carbon.
Total organic emissions from the boiler
were 15 to 17 mg/dscm; of this total, 50
percent were in the C1 to C6 boiling point
range. Of the semivolatile organic priority
pollutants, only naphthalene (at a level less
than 5 ^g/dscm) was detected in flue gas
samples. Of the volatile organic priority
pollutants, emissions of several chlor-
inated C1 and C2 aliphatic hydrocarbons,
chlorobenzene, benzene, and ethylben-
zene were quantitated in the 1 to 20
^g/dscm range.
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 two separate volumes of the same title
(see Project Report ordering information
at back).
Introduction
Coal/water slurries (CWS) have received
attention in recent years as an alternative
to oil fuels. CWS has the advantage of
allowing certain oil-fired boilers to eli-
minate their oil fuel requirements at mod-
est retrofit cost. Thus, CWS has the poten-
tial for conversion of some oil-burning
facilities to coal firing, thereby offsetting
higher oil prices and (frequently) uncertain
supplies. This report gives results of an
emission assessment of a CWS-fired
industrial boiler.
The boiler tested was a Babcock &
Wilcox integral furnace, bent-tube boiler
rated at 7.6 kg steam/s (60,000 Ib/hr) at
1.2 MPa (175 psig) at the Memphis plant
of the E.I. du Pont de Nemours & Com-
pany. The unit was originally designed to
fire distillate oil, process gas, and natural
gas, and had been previously modified to
accommodate residual fuel oil.
The unit was most recently modified to
allow CWS firing under an Electric Power
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Research Institute (EPRI) CWS demonstra-
tion program. The tests reported here were
performed during the 35-day demonstra-
tion burn phase of the EPRI project. A
CWS formulation prepared by the Atlan-
tic Research Corporation (ARC-Coal) was
being fired during the tests performed for
this report.
Summary and Conclusions
Boiler Operation
Table 1 summarizes the boiler operating
conditions for the test. As indicated, three
of the five available furnaces were fired
with the CWS. In addition, about 10 per-
cent of the total heat input to the unit was
with natural gas introduced through one
burner and through a direct-fired air pre-
heater. Boiler load was slightly greater
than 90 percent of rated for the test. Boiler
efficiency as calculated by the ASME/heat
loss method was 72 percent. Table 2 gives
the fuel ultimate analysis reported by the
host site.
Emission Measurements and Results
The sampling and analysis procedures
used in this test program conformed to an
extended EPA Level 1 protocol. All flue gas
was sampled in a vertical section of
breeching, downstream of the units' in-
duced draft fan, but upstream of the
breeching transition section to the stack.
Emission measurements included:
• Continuous monitoring for O2, CO2,
NOX, CO, and TUHC.
• Source assessment sampling system
(SASS) for trace elements and semi-
and non-volatile organic emissions.
• Volatile organic sampling train (VOST)
for volatile organic emissions.
Table 2. CWS Fuel Composition
Component
• Combined EPA Method 5/8 for par-
ticulate and SOX emissions.
• Gas grab samples for onsite C, to C6
hydrocarbon measurement.
• Gas grab samples for laboratory N20
analysis.
In addition, samples of the fuel were col-
lected for analysis. The analysis protocol
included:
• Analyzing the fuel and SASS train
samples for 73 trace elements using
spark source mass spectrometry
(SSMS), supplemented by atomic ab-
Percent by weight
(dry basis unless noted)
Moisture3
Solids3
Carbon
Hydrogen
Oxygen3-1'
Nitrogen
Sulfur
Ash
Higher heating value, MJ/kg
(Btu/lb)
29.7
70.3
83.3
5.1
5.0
1.4
0.6
4.6
34.374
(14,810)
aAs fired.
bBy difference.
Table 1. Boiler Operating Conditions
Parameter
Range
Average
Steam flow, kg/s (JO3 Ib/hr)
Steam pressure, MPa (psig)
CWS flow, l/s (gpm)a
Natural gas flow to burner No. 4,
scm/min (103 scfh)
Natural gas flow to air heater,
scm/min (1O3 scfh)
Inlet air temperature, °C (°F)
Windbox air temperature, °C <°F)
Windbox air pressure, kPa (in. WC)
CWS heater temperature, °C (°F)
CWS strainer discharge pressure, MPa (psig)
Feedwater temperature, °C (°F)
Stack gas temperature, °C (°F)
Atomizing air pressure, MPa (psig)
Burner No. 2
Burner No. 3
Burner No. 4
CWS burner pressure, MPa (psig)
Burner No. 2
Burner No. 3
Burner No. 4
Furnace pressure. Pa (in. WC)
Excess air (percent)1'
Boiler efficiency (percent)0
6.89 to 7.13 (54.6 to 56.5)
1.19 to 1.21 (173 to 176)
0.60 to 0.61 (9.5 to 9.71
1.39 to 1.79 (2.94 to 3.79)
1.58 to 1.76 (3.35 to 3.73)
29 to 39 (85 to 102)
274 to 283 (525 to 542)
279 (11.2)
37 to 38 (98 to 101)
1.35 to 1.38 (196 to 20O)
129 (265)
293 to 304 (559 to 580)
1.41 to 1.42 (204 to 206)
1.42 to 1.43 (206 to 208)
1.41 to 1.42 (204 to 206)
1.13 to 1.16 (164 to 168)
1.12 to 1.14 (162 to 166)
1.16 to 1.23 (168 to 179)
-77 to -37 (-0.31 to -0.15)
7.01 (55.5)
1.21 (175)
0.61 (9.6)
1.48 (3.14)
1.68(3.55)
36 (96)
279 (535)
279 (11.2)
38 (100)
1.37 (198)
129 (265)
299 (571)
1.42 (206)
1.43 (208)
1.42 (206)
1.14 (166)
1.14 (165)
1.21 (176)
-60 (-0.24)
45
72
aAverage of two f/owmeters installed; one magnetic and one mass.
bCalcu/ated from flue gas composition.
cCalculated using "ASME test form for abbreviated efficiency test."
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sorption spectrometry (AAS) and
other techniques.
• Analyzing VOST traps for the volatile
organic priority pollutants.
• Analyzing the SASS train organic ex-
tract samples for total organic con-
tent in two boiling point ranges; 100
to 300 °C by total chromatograph-
able organics (TCO) analysis, and
>300°C by gravimetry (GRAV).
• Analyzing the SASS train extract
samples for the 58 semivolatile or-
ganic species, including many of the
polynuclear aromatic hydrocarbon
(PAH) compounds.
• Performing infrared (IR) spectrometry
analysis of organic sample extracts.
Bioassays were also performed on SASS
train and ash samples to estimate their
potential toxicity and mutagenicity.
Table 3 summarizes flue gas emissions
measured in the test program. Emissions
are presented as nanograms per Joule
heat input and as milligrams per dry stan-
dard cubic meter of flue gas. As a measure
of the potential significance of the emis-
sion levels for further analyses, an occupa-
tional exposure guideline for most pol-
lutants is also noted in the table. The oc-
cupational exposure guideline is either the
time-weighted-average Threshold Limit
Value (TLV) established by the American
Conference of Governmental Industrial
Hygienists, or the 8-hr time-weighted-
average exposure limit established by the
Occupational Safety and Health Adminis-
tration (OSHA). These are noted only to
aid in ranking the potential significance of
the emission levels. In this respect, pollu-
tants emitted at levels several orders of
magnitude higher than their occupational
exposure guideline might warrant further
consideration, while pollutants emitted at
levels significantly lower than their oc-
cupational exposure guideline might be
considered of little potential concern. Only
elements emitted at levels exceeding 10
percent of their occupational exposure
guideline in these tests are noted in Table 3.
As noted in Table 3, particulate emis-
sions from the boiler were quite high
(about 4.3 g/dscm). This is not unex-
pected, however, since the unit had no
particulate control device. The emission
levels for NOX, S02, SO3, CO, and N20
correspond to 510, 450, 2.6, 285, and 70
ppm (corrected to 3 percent O2), respec-
tively. The NOX level noted is in the range
typical for coal-fired sources. The SOX
(SO2 and S03) levels correspond to what
would be expected from this source burn-
ing a 1 percent (dry basis) sulfur fuel. The
Table 3. Summary of Flue Gas Emissions
Emission concentration
Component
Ing/J
heat input)
Major constituents
Particulate
SO2
S03
NOX (as NO2)
CO
N20
Total volatile
organics (C-j to Cg)
Total semivolatile
organics (TCO)
Total nonvolatile
organics (GRAV)
Trace Elements
2,510
540
3.9
440
150
57
8.8
0.03
0.2
a Time-weighted-average TLV unless noted.
bFor nuisance particulate.
cNo occupational exposure guideline applicable.
dCeiling limit.
e8-hr time-weighted-average OSHA exposure limit.
fmg/dscm)
4,310
930
6.7
760
260
98
15.1
0.05
0.3
Occupational
exposure
guideline*
(mg/m3)
5.0
1.0
6.0
55
Beryllium
Aluminum
Iron
Chromium
Silicon
Sodium
Phosphorous
Potassium
Nickel
Lithium
Vanadium
Calcium
Arsenic
Lead
Copper
Barium
Titanium
Cobalt
Magnesium
Zinc
Silver
Selenium
Bromine
Yttrium
0.25
160
47
1.3
225
28
1.1
16
0.67
0.15
0.26
7.5
0.032
O.097
0.19
0.74
9.7
0.070
4.5
0.25
0.0024
0.018
0.063
0.082
0.43
270
80
2.3
385
48
1.9
28
1.2
0.26
0.44
13
0.056
0.17
0.33
1.3
17
0.12
7.7
0.43
0.0041
0.031
0.11
0.14
O.OO2
2.0
1.0
0.050
1Ob
2.0"
0.10
2.0"
0. 10
0.025
0.050
2.0
0.010s
O.O50e
0.10*
0.5O
10"
0.10
10
1.0
0.010
0.20
0.70
1.0
analysis summarized in Table 2 indicates
less sulfur in the fuel. However, an inde-
pendent analysis cited by the host site
suggests that the fuel sulfur content could
have been above 0.9 percent. The ratio of
S03 to total SOX, at 0.6 percent, is lower
than the typical 2 to 5 percent range for
coal fired sources.
Table 3 notes that several trace ele-
ments were emitted at levels significantly
higher than their occupational exposure
guideline. In fact, two elements were emit-
ted at levels over a factor of 100 times
their occupational exposure guideline and
another eight at levels greater than 10
times their guideline. Again, however, this
is largely the result of the absence of a par-
ticulate control device on the boiler for
these tests. In fact, five of the first eight
elements noted in the table (aluminum,
iron, silicon, sodium, and potassium) are
major constituents of the ash fraction of
the CWS fuel. For further comparison, the
criterial pollutants NOX and S02 (in ad-
dition to particulates) were also emitted
at levels over 100 times their occupational
exposure guidelines.
The size distribution of emitted partic-
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ulate was heavily weighted toward coarse
particulate, as noted in Table 4. Over half
of the emitted particulate mass had dia-
meters greater than 10 urn; over 90 per-
cent had diameters greater than 3 urn.
Combustible losses in the particulate were
quite high as noted in Table 5. Composite
particulate had a carbon content of about
40 percent which, with the hydrogen
noted, would give a particulate higher
heating value of 13.7 MJ/kg (5,920
Btu/lb).
Table 3 noted that total organic emis-
sions from the unit were about 15.5
mg/dscm, comprised chiefly (over 95 per-
cent) of compounds in the volatile (boil-
ing point less than about 100 °C) category.
Emissions of both total semivolatile organ-
ics (boiling point between 100° and
300 °C) were 0.05 mg/dscm; of non-
volatile organics (boiling point greater than
300°C) were 0.3 mg/dscm.
Analysis of SASS train samples for the
semivolatile organic priority pollutants
showed that only naphthalene was pre-
sent in the flue gas at detectable levels;
naphthalene emissions were less than 5
ug/dscrn.
Results of VOST testing for volatile or-
ganic compounds are summarized in Table
6, which shows that several chlorinated
C-, and C2 aliphatic hydrocarbons,
chlorobenzene, benzene, and ethylbenzene
were emitted at levels in the 1 to 20
^g/dscm range. Such levels of benzene and
ethylbenzene are common in combustion
source flue gas. The chlorinated com-
pounds also arise whenever chlorine-con-
taining fuels are burned. Although not
noted in Table 2, an independent host site
analysis suggests that the chlorine con-
tent of the CWS burned was 0.1 percent.
Bioassay tests were performed on the
SASS train organic sorbent module extract
and two particulate size fractions. The
health effects bioassays performed were
the Ames mutagenicity assay, and the
CHO cytotoxicity assay. The results of
these assays are summarized in Table 7.
The results suggest that the sorbent mod-
ule extract was of moderate toxicity and
mutagenicity and both particulate size
fractions were of nondetectable mutagen-
icity and low toxicity.
Table 4. Particle Size Distribution
Weight percent
of particulate
Size range in size range
>10 ftm 51.4
3 to 10 ^ 40.4
1 to 3 \un 7.8
>1 urn 0.4
.4
Table 5. Particulate Carbon and Hydrogen Content
Carbon content
Size range (weight percent)
Hydrogen content
(weight percent)
>3 \un (10 \un + 3 \un
cyclone catch)
<3 \un 11 yrr> + filter
catch)
42.67
13.13
0.13
0.09
Composite
40.19
0.13
Table 6.
Stack Gas Volatile Organic Compound Concentrations
Stack gas concentration1''0 (\ig/dscm)
Trap set 1
Trap set 3
Compound1
Chloromethane
Vinyl chloride
Chloroethane
1,2-dichloroethane
Benzene
Chlorobenzene
Ethylbenzene
Tenax
trap
0.4
<0.3
<0.3
0.4
20.9
<0.3
<0.3
Tenax/
charcoal
trap
27.6
5.2
8.2
<0.3
<0.3
<0.3
2.4
Total
28
5.2
8.2
0.4
21
<0.3
2.4
Tenax
trap
<0.3
<0.3
<0.3
<0.3
25.4
1.5
<0.3
Tenax/
charcoal
trap
12.8
8.3
12.9
<0.3
<0.3
<0.3
1.1
Total
13
8.3
12.9
<0.3
25
1.5
1.1
Average
total
21
6.8
11
0.4
23
0.9
1.8
aBromomethane, chloroethane, methylene chloride, 1,1-dichloroethylene, 1,1-dichloroethane,
t-1,2-dichloroethylene, chloroform, 1,1,1-trichloroethane, carbon tetrachloride,
dichlorobromomethane, 1,2-dichloropropane, t-1,3-dichlompropene, trichloroethylene,
2-chloroethyl vinyl ether, bromoform, tetrachloroethylene, 1,1,2,2-tetrachloroethane,
toluene, allyl chloride, ethylene oxide, propylene oxide, and 2-nitropropane were also
analyzed for and not detected above a detection limit of 0.3 ^g/dscm.
hField blank corrected.
^Triplicate sets of traps samples; trap set 2 not analyzed.
The positive Ames responses for the
sorbent module extracts noted above are
typical for such extracts from SASS tests
of combustion sources. Current studies
are investigating if such bioassay respon-
ses are due to artifact compounds formed
when combustion product gas containing
NOX is passed over XAD-2 resin.
Quality assurance (QA) was performed
for these tests to establish the precision
and accuracy of several laboratory ana-
lyses. The precision of the TCO analysis
met the project QA goal for this procedure.
However, only 70 percent of the C, to C6
GC measurements met the QA objective
for this procedure compared to a project
completeness objective of 90 percent.
Deviations occurred in the C1 and C3
quantitations. Since negligible amounts of
C, hydrocarbons were detected in these
tests, this deviation had no effect on pro-
ject conclusions. The deviations in the C3
measurement may introduce factor of 2
differences in cited C3 emissions, which
would introduce factor of 30 percent dif-
ferences in total C-i to C6 hydrocarbon
reported. Such differences would not
significantly alter test conclusions regard-
ing total organic emission dominated by
the volatile (C, to C6) fraction.
Table 7. Bioassay Results
Bioassay
Sample
Ames3
CHOb
XAD-2 extract: M
<3 fan particulate ND
(1 ion + filter)
>3 \tm particulate ND
(3 tun + 10 ton)
M
L
aMutagenicity test
h Toxicity test
M: Moderate, L: Low,
ND: Nondetectable
U. S. GOVERNMENT PRINTING OFFICE:1986/646-l 16/20843
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D. Van Buren and L R. Water/and are with Acurex Corp., Mountain View, CA
94039.
Joseph A. McSorley is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Environmental Assess-
ment of a Coal/Water Slurry Fired Industrial Boiler:"
"Volume I. Technical Results," (Order No. PB 86-183 795/AS; Cost: $11.95)
"Volume II. Data Supplement," (Order No. PB 86-183 803/AS; Cost: $11.95)
The above documents will be available only from: (cost subject to change)
Nation a I 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, NC27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-86/012
0000329 PS
U S ENVIR PROTECTION AGENCY
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