United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-84-095 Nov. 1984
Project Summary
Environmental Assessment of a
Firetube Boiler Firing
Coal/Oil/Water Mixtures
R. DeRosier
This report describes emission results
from sampling of flue gas from a
firetube boiler burning a coal/oil/water
(COW) mixture and the same mixture
with soda ash (sodium carbonate)
(COW+SA) added to control SO2 emis-
sions. Measurements included con-
tinuous monitoring of flue gas emissions;
source assessment sampling system
(SASS) sampling of the flue gas with
subsequent laboratory analysis of
samples to give total flue gas organics
in two boiling point ranges, specific
quantitation of the semivolatile organic
priority pollutant species, and flue gas
concentrations of 73 trace elements;
Method 5 sampling for total participate;
and controlled condensation system
sampling for SOa and SOa emissions.
Flue gas SO2 emissions decreased
almost 99 percent with soda ash
addition from 1,089 to 13.6 ppm (3
percent O2). NOX emissions decreased
slightly from 477 to 427 ppm, while CO
emissions increased significantly from
an average of 25 to 426 ppm (all at 3
percent 02). Particulate loading at the
boiler outlet almost doubled (from
1,970 to 3,715 mg/dscm) with the
additive. The size distribution of parti-
culate also shifted to a much smaller
mean diameter. Total organic emissions
increased from 6.7 to 13.1 mg/dscm,
attributed to increased nonvolatile
(Cie+) organics. Volatile (Ci to C6)
organic emissions remained relatively
constant; semivolatile organics (C? to
Cie) were not detected in either test. Of
the semivolatile organic priority pollu-
tant species, only fluoranthene and
phenanthrene were detected with the
COW fuel at levels of 0.05 and 0.1
/ug/dscm, respectively. Only phenan-
threne was present in the COW+SA flue
gas sample, though at significantly
increased concentration (0.7/ug/dscm).
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory. Research Triangle
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 ordering
information at back).
Introduction
Coal/oil mixtures (COM), coal/oil/
water (COW) mixtures, and coal/water
slurries (CWS) have received attention in
recent years as alternatives to oil fuels in
oil-fired combustion equipment. These
mixtures have the advantage of allowing
an oil-fired boiler to reduce its oil
requirements without completely rede-
signing the boiler. Thus, these fuels have
a potential for application as near-term
technologies for conversion of oil-
burning facilities to partial coal firing,
thereby partially offsetting higher oil
prices and frequently uncertain supply
situations. This report gives results of an
emissions assessment of a COW-fired
firetube industrial boiler with and without
the sorbent soda ash (sodium carbonate)
added to the fuel to control S02.
Boiler Description and Fuel
Properties
A Cleaver Brooks CB400-350 firetube
boiler rated 4.1 MW (14 million Btu/hr)
heat input was used for the tests. At rated
capacity, the unit produces 1.5 kg/s
(12,000 Ib/hr) of saturated 1,030 kPa
(150 psig) steam. The unit uses a four-
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pass design, with tube cross-sectional
area decreasing for each pass. To burn
COW, the boiler was modified to include a
new fuel feed system, enlarged nozzle, an
additional combustion air blower, and
soot blowers.
The COW and COW+SA mixtures were
prepared in-line, prior to being fed to the
boiler. Table 1 gives the fuel composition
in terms of coal, oil, water and soda ash.
Table 2 gives the ultimate analysis of the
mixtures. Despite the reduced proportion
of coal in the COW+SA, the sulfur and
nitrogen contents are nearly equal to
those of the COW fuel.
Table 1. Overall Fuel Composition*
Coal
Oil
Water
Soda ash
COW
42
42
16
COW+SA
38.6
39.2
14.5
7.7
"Percent by weight.
Boiler Operation
The test program called for flue gas
emission measurements firing each of
the two fuels. Table 3 summarizes the
boiler operating conditions for the two
Table 2. Ultimate Fuel Analyses*' b
tests. The addition of soda ash to the
COW resulted in several changes in
operating conditions. Most evident were
that the boiler tubes fouled rapidly, the
flame temperature decreased, and the O2
level at which CO emissions increased
markedly rose from 2.5 to 3.2 percent. As
a result of the rapid fouling during the
COW+SA test, the test had to be termi-
nated after only 3.5 hours; the COW test
ran for the full 6 hours required for a
complete emissions sampling program.
After the tests, 127 kg (281 Ib) of ash
deposits were removed from the boiler,
which had been cleaned prior to the COW
test. Based on fuel composition, fuel
flowrate, and paniculate emission rates,
20 percent of this ash was estimated to be
attributed to the COW test and 80 percent
to the COW+SA tests. Deposits of this
magnitude could preclude using sorbent
injection rates needed to obtain signifi-
cant SOx reduction.
Emission Measurements and
Results
Flue gas emissions measurements were
made at the boiler outlet. The sampling
and analysis procedures used conformed
Carbon
Hydrogen
Nitrogen
Sulfur
Oxygen (by difference)
Ash
Heating value" kJ/kg
(Btu/lb)
Moisture"
COW
78.02
8.60
0.76
1.93
6.69
4.00
31.413
13.491
15.60
COW+SA
71.74
7.83
0.73
1.90
4.63
13.17
26.952
1 1,575
15.54
^Percent by weight.
bO/y basis, except as noted.
cAs received.
Table3. Boiler Operating Conditions
COW
COW+SA
Fuel flow, kg/hr
(Ib/hr)
Boiler feedwater flow, 1/s
(gal. /mint
Excess air, percent3
Temperatures0, °C (°F)
Fuel
Water return
Water supply
Ambient air
Stack
433.5
(955.9)
18.5
(293)
17
25
(77)
82
(179)
124
(256)
23
(74)
146
(295)
429.5
(947. 1)
18.8
(298)
14
32
(90)
80
(176)
' 119
(246)
24
(75)
181
(357)
aBased on stack Oz measurement (percent, dry) and fuel analysis.
''Average over test run.
to a modified EPA Level 1 protocol. Flu
gas measurements included:
• Continuous monitoring for NOX, 02,
CO, C02, and S02.
• Source assessment sampling system
(SASS) for paniculate size fractiona-
tion, trace elements, and organic
emissions.
• Controlled condensation system
(CCS) for SO2 and SO3.
• EPA Method 5 for particulates.
• Grab sample for onsite analysis of Ci
to Ce hydrocarbons by gas chromato-
graphy (GC).
Particulate mass emissions were mea-
sured by Adelphi University personnel
using EPA Method 5. These results are
also summarized in this report.
The analysis protocol included:
• Analyzing SASS train samples for
73 trace elements using spark
source mass spectrometry (SSMS),
supplemented by atomic absorption
spectrometry (AAS).
• Analyzing SASS train samples for
total organic content in two boiling
point ranges: 100 to 300°C by total
chromatographable organics (TCO)
analysis and greater than 300°C by
gravimetry (GRAV).
• Analyzing the SASS train sorbent
module and paniculate extracts for
58 semivolatile organic species
including many of the POM com-
pounds.
• Performing infrared (IR) spectrometry
analysis of organic sample extracts.
• Performing liquid chromatography
(LC) separation of total sample
extracts with subsequent GRAV and
IR analyses of LC fractions.
• Performing direct insertion probe
low resolution mass spectrometry
(LRMS) analysis of selected total
sample and LC fraction extracts.
• Determining the alpha and beta
radiometric activity of the SASS
paniculate.
• Performing mutagenicityandtoxicity
health effects bioassays on SASS
sorbent module extract samples.
Table 4 summarizes emissions mea-
sured in the test program. Emissions are
presented as nanograms per Joule heat
input (ng/J) and micrograms per dry
standard cubic meter of the flue gas
(/ug/dscm). As a measure of the relative
potential significance of the emission
levels for further analysis, an occupa-
tional exposure guideline concentration
for each species is also noted in the table.
The occupational exposure guideline
noted is either the time-weighted-
average Threshold Limit Value (TLV) o
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the 8-hr time-weighted-average expo-
sure limit established by the Occupational
Safety and Health Administration (OSHA).
Only species emitted at levels exceeding
10 percent of their occupational exposure
guidelines in either (or both) tests are
noted in Table 4.
As noted in the table, several trace
elements were present at significant
levels in the boiler outlet flue gas for
either or both tests. However, flue gas
paniculate accounts for the major fraction
of these elements in the flue gas at this
Table 4. Emission Summary
location. Ultimate flue gas discharge
concentrations would be significantly
reduced after passage through the unit's
particulate control device.
Emissions of SOz decreased signifi-
cantly using the soda ash additive;
changes in emission levels of other
species were less substantial. The data in
Table 4 suggests that the most significant
environmental effect of soda ash addition
for SO2 control would be the attendant
reduction in SO2 emissions.
Tables 5 and 6 summarize organic
emission results for the COW and
COW+SA tests, respectively. The top
portion of each table summarizes the
total chromatographable organic (TCO)
content and the GRAV organic content of
the XAD-2 sorbent extract as it eluted into
the seven LC fractions. The bottom
portion of each table summarizes the
organic categoreis identified by LRMS of
the LC fractions with inferences from the
IR spectroscopy. Organic matter collected
in the XAD-2 sorbent accounted for
approximately 100 and 60 percent ot total
COW test
Emission concentration
COW+SA test
"Time-weighted-average TLV, unless noted.
"Method 5 not performed for the COW test.
cFor nuisance particulate
°No occupational exposure guideline applicable.
"8-hr time-weighted-average OSHA exposure limit.
'Ceiling limit.
Occupational
exposure
Compound
S02
SO3
/VOx
CO
Particulate
Method 5
SASS
Total volatile
organ ics (Ci to C*J
Total semivolatile
organics (TCO)
Total nonvolatile
organics (GRA V)
Trace Elements
Chromium
Barium
Phosphorous
Lead
Vanadium
Arsenic
Nickel
Beryllium
Iron
Platinum
Lithium
Uranium
Fluorine
Copper
Zinc
Chlorine
Silver
Calcium
Mercury
Selenium
Potassium
Cobalt
Sodium
Magnesium
Manganese
Titanium
Thallium
Silicon
Yttrium
Bromine
(mg/dscmj
2,900
20
900
29
— b
1,970
3.8
<0.04
2.9
>1.1
>1 2
>20
0.78
0.92
0.1 6
>1.1
0012
2.7
0.0016
0.11
0.15
0.14
0.13
>1.1
0.15
<0 00087
>1.8
O.OO047
0.16
>1.5
0029
>0.79
>2.0
>1.1
>2.0
0.020
>1.4
0.13
0.049
(ng/J)
1.060
0.74
332
11
—
722
1.4
<0.01
1.1
>0.39
>0.44
>072
0.29
0.34
0.059
>O.38
0.0045
1.0
0.00060
0.039
0.055
0.050
0.047
>0.38
0.055
<0.00032
>0.66
0.000/7
0058
>0.56
0.011
X).29
>0.73
>0.39
>0.73
0.0072
>0.51
0.046
0.018
(mg/dscm)
36
—
830
490
3.720
3,720
4.1
<0.02
9.0
0.40
1.1
0.85
0.93
0.68
<0.089
0.65
0.0028
5.3
0.011
0.033
<0.068
0.41
0.14
0.28
3.3
0.0095
>1.1
<0.085
0.067
>1.2
<0.0097
>0.85
>2.3
0.41
1.7
0.0085
>1.0
0.040
0.076
(ng/J)
14
—
350
195
1,460
1,460
1.6
<0.01
3.5
0.16
0.42
0.33
0.37
0.27
<0.035
0.26
0.0011
2.1
0.0042
0.013
<0.027
0.16
0.055
0.11
>1.3
0.0038
>0.43
0.46
0.34
>0.92
0.16
0.67
0.0033
>0.41
0.016
0.030
guideline' (mg/rr
5.0
1.0
6.0
55
iff
a
a
a
0.050"
0.50
0.10
0.050
0.050
0.010"
0.10
0.0020
1.0
0.0020
0.025
0.060"
0.20"
0.10"
1.0
3.0
0.010
2.0
0.10
0.20
2.0'
0.050
2.0'
10
5.0'
10C
0.10
10°
1.0
0.70
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Table 5. Organic Extract Summary —COW XAD-2 EXTRACT
LCI LC2 LC3 LC4 LC5 LC6 LC7 Total
Total organics, mg 14 12 10 <2<2 6 3 45
TCO, mg — — ____ _
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R. DeRosier is with Acurex Corporation, Mountain View. CA 94039.
Robert E. Hall is the EPA Protect Officer (see below).
The complete report consists of two volumes, entitled "Environmental Assess-
ment of a Firetube Boiler Firing Coal/Oil/Water Mixtures:"
"Volume I. Technical Results," (Order No\ PB 85-108082; Cost: $13.00)
"Volume II. Data Supplement," (Order No. PB 85-108 090; Cost $ 17.50)
The above reports will be available only from: (costs subject to change)
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
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
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