Biomass-Fueled, Small-Scale, Integrated-Gasifier, Gas-Turbine Power Plant: Progress Report on the Phase 2 Development

BIOMASS-FUELED, SMALL-SCALE, INTEGRATED-GASIFIER,
GAS-TURBINE POWER PLANT:
PROGRESS REPORT ON THE PHASE 2 DEVELOPMENT
Carol R. Purvis
U.S. Environmental Protection Agency, Office of Research and Development,
National Risk Management Research Laboratory
86 T.W. Alexander Drive, MD-63, Research Triangle Park, NC 27711, USA
Phone (919) 541-7519; Fax (919) 541-7885; Email purvis.carol@epa.gov
Joe D. Craig
Cratech, Inc.
P.O. Box 70, Tahoka, TX 79373, USA
Phone (806) 327-5220; Fax (806) 327-5570; Email jcraig@cratech.com
ABSTRACT
Cratech, Inc. is progressing with a three-phase effort to develop a family of small-scale
(1 to 20 MWe) biomass-fueled power plants. The biomass power plant concept
envisioned is an air-blown pressurized fluidized-bed gasifier followed by a dry hot gas
cleanup system with the resulting clean hot gas injected into the combustion chamber of
a gas-turbine engine.
Phase 1 was the design, construction, and operation of the pressurized feed system,
gasification system, and hot gas cleanup of a slipstream. Phase 2 is the design and
construction of an upgraded gasification system based on the Phase 1 results. It also
includes a full-flow hot gas cleanup filter based on the slipstream filter of Phase 1. This
system is capable of providing pressurized hot clean gas for fueling a gas-turbine engine.
Phase 3 is the modification of a gas-turbine engine to operate on the fuel produced by the
Phase 2 system. A small gas-turbine-generator package has been procured and will
provide for economical fuel system and combustor modification, and subsequent testing.
When the Phase 2 and 3 systems are complete and tested, they will be integrated to form
a complete small-scale biomass power system which will undergo performance testing.
This paper reports the latest efforts to complete development of Phase 2. A general
overview of the process and performance of the system will be presented.
Keywords: Pressurized feed system, pressurized gasification, gas turbine, gas cleaning,
low calorific gas

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INTRODUCTION
Cratech, Inc. is progressing with a three-phase effort to develop a family of small-scale
(1 to 20 MWe) biomass-fueled power plants. The biomass power plant concept
envisioned is an air-blown pressurized fluidized-bed gasifier followed by a dry hot gas
cleanup system with the resulting clean hot gas injected into the combustion chamber of
a gas-turbine engine.
The effort has been undertaken to develop and demonstrate:
< reliable and commercially competitive power generation from a
technology that has not yet been demonstrated at this scale,
< a non-polluting energy source using renewable fuel without a net
increase in greenhouses gas emissions, and
< an environmental and economical alternative to landfilling or open-
burning biomass residues to provide or supplement power for
government installations, industrial sites, rural cooperatives, small
municipalities, and regions of developing countries.
Phase 1 was the design, construction, and operation of the pressurized feed system,
gasification system, and hot gas cleanup of a slipstream. The Phase 1 system was
operated at a feed rate of 0.5 metric ton per hour (mtph) [0.55 ton per hour (tph)] and 2
atmospheres (atm) (202 kPa). Phase 1 is complete. (Craig 1996)
Phase 2 is the design and construction of a new gasification system based on the Phase 1
results. The Phase 2 system has been upgraded to a feed rate of 1 mtph (1.1 tph) and a
design operating pressure of 12 atm (1216 kPa). It also includes a full-flow hot gas
cleanup filter based on the slipstream filter of Phase 1. The Phase 2 biomass feed
metering system is now gravimetric rather than volumetric. This system is capable of
providing pressurized hot clean gas for fueling a gas-turbine engine.
Phase 3 is the modification of a gas-turbine engine to operate on the fuel produced by the
Phase 2 system. A small gas-turbine engine was procured for this effort. The gas turbine
is a Solar Spartan rated at 225 kWe with a pressure ratio of 4.0 that will provide for
economical fuel system and combustor modification, and subsequent testing. A modified
combustor for this turbine has been designed (Craig and Purvis 1998). Assembly of the
total low calorific value (LCV), gas-fueled, turbine package is in progress. When the
Phase 2 and 3 systems are complete and tested, they will be integrated to form a complete
small-scale biomass power system which will undergo performance testing.
SYSTEM DESCRIPTION
Referring to Figure 1, the biomass is loaded into the live-bottom bulk biomass feeder.
The biomass is transported through a fan-driven pneumatic conveying system and an
inlet valve into one of two identical biomass pressurization vessels (BPVs), only one

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Figure 1. System Diagram

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BPV is shown in Figure 1. The biomass drops out of the airstream and settles into the
BPV. The air exits through a valve. When the BPV is filled with biomass, the inlet and
exhaust valves close and the BPV is pressurized with air. When the pressure between the
BPV and the meter vessel (MV) is equalized, the discharge valve opens and supplies the
meter vessel with biomass. The MV is under constant pressure and gravimetrically feeds
biomass to the reactor vessel at a set rate. When the level of biomass in the BPV reaches
its low level, the discharge valve closes and biomass is supplied through the other BPV
and discharge valve, which completes its fill and pressurization cycle while the other
BPV is emptying. The empty BPV depressurizes and begins its fill cycle again.
The reactor vessel contains a pressurized fluid bed. The reactor receiving the metered
biomass is supplied air from an air compressor. The fuel and air mix and react in the
fluid bed at a maximum temperature of 760 °C. The product of the reaction is a
combustible fuel gas laden with ash particles. The gas flows through a transition vessel
into the high-temperature gas filter vessel. The filter vessel separates the ash from the
gas. The ash falls to the bottom of the filter vessel, and the cleaned gas flows upward
into the gas distribution manifold. The ash continues to flow downward into an ash
cooler. Heat is removed from the ash until its temperature reaches approximately 65°C.
The ash exits the cooler, then flows through a depressurization system. The ash is then
conveyed to a short-term storage hopper. The clean gas is directed from the gas
distribution manifold to a gas flare, a gas sampling train, and/or the gas-turbine.
SYSTEM PERFORMANCE
The Phase 2 gasification system design is complete and construction is complete except
for the hot gas filtration system, which is 95% complete. Shakedown testing of the
system, bypassing the high-temperature gas filter, has begun. Four shakedown runs
ranged from 30 minutes to 2 hours in duration and yielded valuable data. The operators
have tested, and are continuing to test, the system to refine the process control
programming and to vary operating parameters for optimizing performance of the
gasification system. These runs also identified wiring/hardware integrity issues.
Run 1: This 30-minute run was terminated due to a feed system programming error.
Run 2: The load cell signal of the gravimetric feed system was lost. The signal loss
caused the biomass metering system to shut down after 80 minutes.
Run 3: This 110-minute run was terminated due to a feed system programming error.
Run 4. During this 120-minute run, steady-state operation of the gasifier was achieved.
This achievement was the result of identifying the optimum operating parameters that
allowed for controlling the gasifier. During the steady state operation , the average bed
temperature in the gasifier was held at 760 +/- 2 °C. Most major programming errors
were apparently corrected. This run was terminated when an electrical connection to a
valve limit switch failed, triggering a shutdown. Figure 2 shows the performance of run
4.

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70-
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on
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Reactor Pressure (psig) (14.7 psi = 1 atm= 101 kPa)
100
150
200
250
Figure 2. Performance of Phase 2 System During Run 4 (06/05/2000)
With the success of defining the operating parameters that allow for steady state
operation of the gasifier, it was decided to proceed with bringing the hot gas filtration
subsystem online. Some additional piping and programming are required, and testing
with the hot gas filtration subsystem was scheduled to begin in August 2000.
DESCRIPTION OF SAMPLING
Gas will be analyzed to determine the molar composition and concentration of reactant
products, particulate concentration, and alkali content. From the manifold, on the outlet
side of the high-temperature gas filter vessel, gas can be diverted to the gas sampling
train. The gas sampling train has been designed and fabricated to provide ports for the
connection of gas sampling equipment. The train is installed on a portable table for the
convenience of connecting and disconnecting the train and gas sampling equipment from
the manifold.
The sampling equipment consists of an EPA Method 5 and Method 29 train, a gas
chromatograph, and analyzers for carbon dioxide (C02), nitrogen oxides (NOx), and
oxygen (02). The EPA Method 5 train will collect particulate for analysis. The EPA

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Method 29 train (the multiple metals train) will be used to collect samples for analysis of
alkalis. A Hewlett Packard 5890 Series II Gas Chromatograph (GC) has been configured
to measure the molar concentrations of hydrogen (H2), nitrogen (N2), carbon monoxide
(CO), methane (CH4), and C02.
When Cratech is satisfied with the operation and performance of the gasification system,
including the high-temperature gas filtration subsystem, sampling will begin.
REFERENCES
1.	Craig, Joe D., 1996, "Development of a Small Scale Biomass-Fueled Integrated-
Gasifier Gas Turbine Power Plant: Phase 1," Final Report for the DOE Western
Regional Biomass Energy Program, 66 pages.
2.	Craig, Joe D. and Carol R. Purvis, 1998, "A Small Scale Biomass Fueled Gas
Turbine Engine," Transactions of the ASME, 98-GT-315, 5 pages.

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N RMRI - DTD- TECHNICAL REPORT DATA
11 ru»iiu-j rv J. i Jr u*±o (Please read Instructions on the reverse before completing)
1. REPORT NO. 2.
EPA/600/A-00/106
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Biomass-fueled, Small-scale, Integrated-gasifier.
Gas-turbine Power Plant: Progress Report on the
Phase 2 Development
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Carol R. Purvis (EPA) and Joe D. Craig (Cratech)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Cratech, Inc.
P. O. Box 70
Tahoka, TX 79373
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
EPA PR0C-R219-NASA
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Published paper; 4~8/00
14. SPONSORING AGENCY CODE
EPA/600/13
15. supplementary notes ^PPCD project officer is Carol R. Purvis, Mail Drop 63, 919/
541-7519. For presentation at Bioenergy 2000 Conference, 10/17/00, Buffalo, NY.
16. abstract rj-^g paper reports the latest efforts to complete development of Phase 2 of
a three-phase effort to develop a family of small-scale (1 to 20 MWe) biomass-fueled
power plants. The concept envisioned is an air-blown pressurized fluidized-bed
gasifier followed by a dry hot gas cleanup system with the resulting clean hot gas
injected into the combustion chamber a gas-turbine engine. A general overview of
the process and performance of the system is presented. Phase 1 was the design,
construction, and operation of the pressurized feed system, gasification system,
and hot gas cleanup of a slipstream. Phase 2 is the design and construction of an
upgraded gasification system based on Phase 1 results, including a full-flow hot gas
cleanup filter based on the slipstream filter of Phase 1 (the system can provide pres-
surized hot clean gas for fueling a gas-turbine engine). Phase 3 is the modification
of a gas-turbine engine to operate on the fuel produced by the Phase 2 system. A
small gas-turbine-generator package has been procured and will provide for econ-
omical fuel system and combustor modification, and subsequent testing. When the
Phase 2 and 3 systems are complete and tested, they will be integrated to form a
complete small-scale biomass power system which will undergo performance
testing.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS ATI Field/Group
Pollution
F uels
Biomass
Gasification
Gas Turbine Power Generation
Gas Turbines
Pollution Control
Stationary Sources
Gas Cleaning
Low-calorific Gas
13 B
21D
06C
13H, 07A
10A
13 G
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
6
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)

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