United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S7-86/006 Apr. 1986
SEPA Project Summary
Environmental Assessment:
Source Test and
Evaluation Report—
Stoic Low-Btu Gasifier
M. R. Fuchs, M. A. McDevitt, D. S. Lewis, and C. E. Hudak
The report gives results of a source
test and evaluation of the Foster
Wheeler/Stoic gasifierat the University
of Minnesota- Duluth. The test, from
February 23 to March 6, 1981, was
designed to collect data pertinent to an
environmental assessment of the
Foster Wheeler/Stoic two-stage
gasification process, including
evaluation of the emissions from the
combustion of both the product gas and
the by-product electrostatic
precipitator (ESP) oil.
Distribution of minor and trace
elements in the product, by-product,
and discharge streams was calculated
from elemental mass flow rates.
Elemental behavior was also evaluated
by comparing the concentration of an
element in a stream to the
concentration of the element in the ash
mineral fraction of that stream.
Extractable organic material in
product gas, by-product ESP oil, and
discharge streams was characterized
by total organic loading and by gas
chromatographic analysis. Priority
pollutants were identified and
quantitated for major streams. The gas
clean-up devices (ESP and cyclone)
were evaluated for both efficiency and
effects on the gas composition.
Test results indicated that
combustion of ESP oil and product gas
destroyed priority organic pollutants to
the extent that less than 1 percent of the
original levels were detected. Also,
most of the hydrocarbons (C1-C6)
present in the combined product gas
were destroyed by combustion.
Although federal New Source
Performance Standards (NSPS) do not
apply to the Foster Wheeler/Stoic
gasifier boilers because of their size, if
these standards were applied, S02
emissions would fall slightly above or
slightly below NSPS levels, depending
on the method of calculation. NOx
emissions would be marginally above
NSPS, and emission levels of
particulates would fall well below
NSPS.
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 a separate report of
the same title (see Project Report
ordering information at back).
Introduction
From February 23 through March 6,
1981, a source test and evaluation was
performed at the Foster Wheeler/Stoic
two-stage gasifier at the University of
Minnesota-Duluth (UMD). The UMD
constructed the gasifier with funding
from the Department of Energy's (DOE)
"Gasifiers in Industry" Program. The
purpose of the test was to gather data for
the environmental assessment of
commercially viable low—and medium—
Btu coal gasification systems and to
evaluate the emissions from the
combustion of both the product gas and
the by-product electrostatic precipitator
(ESP) oil.
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The resulting report presents the
findings of a limited environmental
'assessment of the two-stage gasifier
developed by Stoic Combustion (Pty.),
Ltd., of Johannesburg, South Africa, and
marketed by Foster Wheeler Energy
Corporation. The test program was
conducted as part of a joint field test effort
between Oak Ridge National Laboratories
(ORNL) and EPA.
Test Overview
The source test, designed to collect
data pertinent to the environmental
assessment of the Foster Wheeler/Stoic
gasifier, was conducted under "steady
state" operating conditions. The
bituminous fuel coal used during the test
program was mined from the Pinnacle
Seam by Sun Coal Co., Milner, Colorado.
About 280 metric tons of bituminous coal
was gasified at an average rate of 270 g/s
(2140 Ib/hr) during the 12-day test.
Major discharge and process streams of
the gasification process were
characterized to assess their potential
impacts on the environment. Streams
were selected for testing according to five
program objectives:
• Performance of an environmental
assessment of the Foster
Wheeler/Stoic two-stage gasifica-
tion process, including the gaseous
discharge streams resulting from
combustion of the product gas and
by-product ESP oil.
• Calculation of material balance.
• Evaluation of emissions from
combustion of the product gas as
related to product gas composition.
• Evaluation of emissions from
combustion of ESP oil as related to
ESP oil composition.
• Evaluation of the efficiency of
product gas clean-up systems (ESP
and cyclone) and their effect on gas
composition.
Samples were collected from five
gaseous process streams: combined
product gas, raw top product gas, treated
top product gas, raw bottom product gas,
and treated bottom product gas. An ESP,
designed and fabricated by Radian under
a previous contract with ORNL, was used
to collect samples of the aerosolized oils
from the process gas stream. Grab
samples for quantitation of major gases,
hydrocarbons, and sulfur species were
collected in cleaned, silanized glass
bombs. Paniculate matter in the gas
streams which did not contain
aerosolized oils was collected on glass
fiber filters.
Trace organic and trace element
samples were collected from two
combustion emission streams using the
High Volume Source Assessment
Sampling System (SASS). Sulfur oxides
(SPx) and particulate matter were
quantitated in the combustion emissions
using combined EPA Methods 5 and 6,
and nitrogen oxides (NOx) were
quantitated in the combustion emissions
using EPA Method 7.
Three solid streams were sampled
during the tests: coal, gasifier ash, and
cyclone dust. Coal samples were
collected as the coal fell from the
conveyor belt into the weigh hopper, and
the ash samples were collected as the
ash fell from buckets onto the conveyor
belt. Dust removed from the bottom
product gas by the cyclone was collected
in a lockhopper.
Three liquid streams were sampled:
ESP oil to storage, ESP oil to boiler No.3,
and ash pan water. Samples of the ESP oil
were collected through a valve in the
transport line between the ESP and
storage tank. Samples of the ESP oil to
boiler No.3 were collected through a
valve in the transfer line between the
pump and boiler. Ash pan water samples
were collected directly from the ash pan.
Results
Material and major component
balances around the gasifier closed
within 3-14 percent. Carbon and sulfur
showed the greatest difference between
mass in and mass out. The gasifier had a
cold gas efficiency (measure of the ability
of a gasifier to convert potential com-
bustion energy in coal to potential
combustion energy in dry, tar-free
product gas) of 80 percent during the
tests.
Material and component balances
around the product gas boilers closed
within 10-50 percent, while material and
component balances around the boiler
firing ESP oils indicated closure within 4-
10 percent for all species except sulfur.
Analytical data allowed an evaluation
of the elemental behavior of 65 elements.
Of these, 43 had 95 percent or more of
their mass discharged in the gasifier ash.
Five elements (antimony, bromine,
chlorine, sulfur, and tin) had more than
25 percent of their total mass in the
combined product gas stream and exhibit
volatile behavior.
Most extractable organic materials
leaving the gasification process are found
in the ESP oil and product gas streams
and are combusted in the boilers.
Combustion of the ESP oil and product
gas destroyed priority pollutants to the
extent that less than 1 percent of the fuel
priority pollutants were found in the
emissions from ESP oil combustion and
less than 1 percent of the priority
pollutants found in the product gas were
detected in the combustion emissions.
Also, most of the hydrocarbons (C1-C6)
present in the combined product gas
were destroyed by combustion.
The collection efficiency of the ESP
used to remove aerosolized oils and
particulate matter from the top product
gas was about 98 percent for oils and 72-
74 percent for particulate matter. The
collection efficiency of the cyclone could
not be evaluated from the data because of
inconsistent gas flow at the sampling
point.
The composition data for ash pan water
indicated that the concentration of
barium and mercury exceed the National
Interim Primary Drinking Water
Standards. However, this comparison is
between process wastewater and
drinking water standards which are
intended to be non-enforceable
guidelines relating to aesthetic qualities
and public acceptance of drinking water.
The gasifier ash and cyclone dust streams
would be considered non-hazardous
according to RCRA criteria.
Although federal New Source
Performance Standards (NSPS) do not
apply to these boilers because of their
size, if they were applied, emission levels
of particulates would be well below
NSPS. S02 emissions would be slightly
above or slightly below NSPS, depending
on the method of calculation, and NOx
emissions would be marginally above
NSPS.
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M. Fuchs, M. McDevitt, D. Lewis, and C. Hudak are with Radian Corporation,
Austin. TX 78766.
William J. Rhodes is the EPA Project Officer (see below).
The complete report, entitled "Environmental Assessment: Source Test and
Evaluation Report—Stoic Low-Btu Gasifier," (Order No. PB 86-167 012/AS;
Cost: $28.95, 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
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