United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-93/170 December 1993
&EPA Project Summary
Biomass Gasification
Pilot Plant Study
A.M. Furman, S.G. Kimura, R.E. Ayala, and J. F. Joyce
A gasification pilot program carried
out at General Electric's (GE's) Re-
search and Development Center, using
two biomass feedstocks: bagasse pel-
lets and wood chips. The object of the
testing was to determine the properties
of biomass product gas and its suit-
ability as a fuel for gas-turbine-based
power generation cycles. The feed-
stocks were gasified at a feed rate of
about 1 ton/hr*, using GE's pressur-
ized, fixed-bed gasifier and a single
stage of cyclone paniculate removal,
operating at 538°C. The biomass prod-
uct gas was analyzed for chemical com-
position, paniculate loading, fuel-bound
nitrogen (FBN) levels, and sulfur and
alkali metal content.
Both feedstocks gasified easily. The
composition and heating value of the
biomass product gas were compatible
with gas turbine combustion require-
ments. However, the paniculate removal
performance of the pilot facility single-
stage cyclone did not meet turbine
specifications. In addition, alkali metal
compounds in the paniculate matter (at
538°C) carried over from the gasifier
exceeded turbine limits. Improved par-
ticulate removal technology, designed
specifically for biomass feedstock char-
acteristics, could meet turbine require-
ments for both paniculate and alkali
loading. FBN compounds were also
measured since they can be convened
to nitrogen oxides (NOx) during com-
*Readers more familiar with metric units may use the
following factors to convert to that system: 1 ton = 907
kg, and 1 atm = 98 kPa.
bustion in a gas turbine. Since this
conversion is highly dependent on gas
turbine combustor design, no firm con-
clusions regarding NOx production can
be reached without actual combustion
testing.
This Project Summary was developed
by the U.S. EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The gasification performance of two bio-
mass feedstocks—wood chips and ba-
gasse—was evaluated in the pilot Inte-
grated Gasification Combined Cycle
(IGCC) facility located at GE's Research
and Development Center in Schenectady,
NY. The overall objective of this program
was to evaluate biomass as a feedstock
for a biomass gasification/gas turbine sys-
tem, which is a potentially cost-effective
and highly efficient approach for using for-
est and agricultural wastes for power gen-
eration. Specific objectives were to mea-
sure gas composition and to determine
whether the product gas would meet gas
turbine requirements.
The pilot IGCC facility consists of a
pressurized, fixed-bed gasifier with a nomi-
nal operating pressure of 20 atm and a
hot gas cleanup system, consisting of a
high-temperature cyclone, a solid-sorbent
desulfurization system, and a polishing
cyclone. The gasifier has a nominal ca-
pacity for coal gasification of 1 ton/hr.
Since desulfurization is not an issue for
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the biomass feedstocks evaluated, only
the gasifier and high-temperature cyclone
were used. The product gas was flared.
Because the pilot gasifier and its asso-
ciated fuel feeding system were designed
for operation on coal, the issue of feeding
of biomass, with its lower density and
different flow properties, was addressed
before gasification testing. Bagasse, which
was supplied as small cylindrical pellets,
was found to feed easily with some modi-
fications to the fuel feeding equipment.
However, it was necessary to evaluate
several wood chip samples before one
was found that could be fed at the re-
quired feed rate.
A total of 42.5 tons of bagasse was
gasified during a 32-hr test, and 83.8 tons
of wood chips were gasified in an 81-hr
test. These quantities of fuel represented
the total fuel available to the program.
Wood chips were provided by the Ver-
mont Department of Public Service. The
bagasse pellets were obtained from the
Winrock International Institute for Agricul-
tural Development.
Both biomass fuels gasified readily.
Their reactivity was higher than that for
coal. Gasification capacities of both fuels
were limited by feed rate or system ca-
pacity, and not by gasification kinetics.
Product gas compositions for both biom-
ass feedstocks indicated that they would
have combustion characteristics compat-
ible with gas turbine combustor require-
ments. However, particulate removal per-
formance of the single cyclone was inad-
equate to meet fuel contaminant specifi-
cations. In particular, alkali metals, which
are present in the fine particulate material
carried over from the gasifier and which
cause hot corrosion on gas turbine hot
gas path components, were present at
levels well in excess of turbine specifica-
tion limits. The low density of particulates
and their poor flow properties, which made
removal from the cyclone difficult, caused
the cyclone to perform poorly. This result
was not unexpected since the cyclone had
been designed for removing contaminants
from coal gas. In order to achieve con-
taminant levels consistent with gas tur-
bine requirements, it will be necessary to
improve particulate removal. This improve-
ment is well within the state-of-the-art of
particulate cleanup technology.
A second class of contaminant mea-
sured was fuel-bound nitrogen (FBN) com-
pounds. Typical of these are ammonia,
cyanides, and nitrogen-containing organic
compounds. A large fraction of FBN will
be converted to nitrogen oxides (NOx) dur-
ing combustion in conventional gaxs tur-
bine combustors. Thus, when stringent NOx
emissions requirements (< 10 ppm) are in
effect, it may be necessary to consider
alternative approaches to reducing the
level of this pollutant. One potential ap-
proach is to utilize advanced combustion
techniques such as "rich-quench-lean" to
reduce the conversion of FBN. This tech-
nology is still in an early stage of develop-
ment and will require significant effort to
bring it to a suitable stage of commercial
readiness. A second approach is to cool
the fuel gas and "scrub" the gas with wa-
ter to remove the FBN compounds. This
approach lowers the overall plant effi-
ciency, reduces the heating value of the
fuel, and creates an environmental dis-
posal problem associated with the dis-
posal of the "scrub" water. Other ap-
proaches include the use of commercially
available selective catalytic reduction
(SCR) technology to reduce the NO level
in the exhaust gas. Note that FBNJ pro-
duction is a strong function of both the
feedstock and gasifier, with higher tem-
perature gasifiers such as fluidized and
entrained gasifiers producing less FBN
than fixed-bed gasifiers. A system trade-
off study would help determine the best
system level approach to NOx reduction
by identifying the capital equipment cost
differences and the associated plant effi-
ciency impact on the overall system de-
sign.
The tests at the GE-CRD pilot plant
have demonstrated the successful gasifi-
cation of biomass and the general suit-
ability of biomass fuel gas for use in a gas
turbine. Areas of possible future develop-
ment include improved particulate removal,
improved low NOx combustion, and pre-
and post-gas cleanup.
These accomplishments represent a key
step in the overall development of a
Biomass-IGCC power generation system
-&U.S. GOVERNMENT PRINTING OFFICE: I«W4 - 550-067/80140
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A. Furman, S. Kimura, R. Ayala, and J. Joyce are with GE Research and Develop-
ment Center, Schenectady, NY 12301.
Carol R. Purvis is the EPA Project Officer (see below).
The complete report, entitled "Biomass Gasification Pilot Plant Study," (Order No.
PB94-114766/AS; Cost: $27.00; 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
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