Gasification Technologies 2005

October 9 – 12, 2005, San Francisco, California, USA

KBR TRANSPORT GASIFIER

Peter V. Smith (peter.smith2@halliburton.com: 205-670-5071)
KBR, P. O. Box 1069, Wilsonville, Alabama, USA, 35186

Nicola Salazar (nicola.salazar@halliburton.com: 713-753-6833)

KBR, P. O. Box 3, Houston, Texas, USA, 77001-0003

Brandon M. Davis (bmdavis@southernco.com: 205-670-5864),

Roxann Leonard (rfleonar@southernco.com: 205-670-5863),
J. Matt Nelson (jmnelson@southernco.com; 205-670-5065)
Southern Company, P. O. Box 1069, Wilsonville, Alabama, USA, 35186

Ronald W. Breault (Ronald.breault@netl.doe.gov: 304-285-4486)

National Energy Technology Laboratory, P. O. Box 880, 3610 Collins Ferry Road,
Morgantown, WV 26507-0880
(KBR Paper 1934)

Abstract
The KBR Transport Gasifier is an advanced circulating fluidized bed reactor designed to operate
at higher circulation rates, velocities and riser densities than a conventional circulating fluidized
bed. The KBR Transport Gasifier is a more robust, simple design and operates in the temperature
range of 1,600 to 2,000ºF which allows it to use less expensive and longer lasting refractory than
the commercially available gasifiers that operate at higher temperatures. The Transport Gasifier is
based on KBR’s extensive fluid bed catalytic cracking experience.

The KBR Transport Gasifier is currently being tested at the Power Systems Development Facility
(PSDF), an engineering scale demonstration of advanced coal-fired power systems and high-
temperature, high-pressure gas filtration systems. The PSDF was designed at sufficient scale so
that advanced power systems, components, and DOE’s Clean Coal Roadmap program elements
could be tested in an integrated fashion to provide data for commercial scale-up. The PSDF is co-
funded by the U. S. Department of Energy, the Electric Power Research Institute, Southern
Company, Kellogg Brown & Root, Inc. (KBR), Siemens-Westinghouse, Peabody Energy, the
Lignite Energy Council and Burlington Northern Sante Fe Corporation.

The KBR Transport Gasifier was operated for three years as a pressurized combustor until coal
gasification testing began in September 1999. Through September 2005, the Transport Gasifier
has achieved over 7,700 hours of coal gasification. A total of 6,320 hours of gasification were
with Powder River Basin coal and 750 hours were with North Dakota lignite. Additional hours
were devoted to bituminous coals from Utah, Illinois, Indiana and Alabama. Most testing
occurred in air blown gasification mode, a characteristic that differentiates it from its competitors.
It has also been tested for a total of 1,722 hours in oxygen-blown mode. The gasifier has operated
at temperatures from 1,500 to 1,950°F and at pressures of up to 250 psig with coal rates of 2,500
to 5,000 pounds per hour, yielding commercially projected turbine inlet syngas heating values of
up to 147 Btu/SCF in air-blown gasification and up to 298 Btu/SCF in oxygen-blown gasification.
Carbon conversion has been as high as 98%.
1
The Transport Gasifier technology is the basis for an advanced 285 to 330-megawatt coal
gasification demonstration project to be located in Orlando, Florida, which will be partially funded
by the DOE under its Clean Coal Power Initiative (CCPI).

Process Description
Disengager
The Transport Gasifier is an advanced
circulating fluidized-bed reactor operating
in air or oxygen blown mode. The Syngas to
Transport Gasifier train is shown Riser Cooling & PCD
Cyclone
schematically in Figures 1 and 2. Figure 1
Mixing Loopseal
shows the different sections of the Zone
Cyclone
Transport Gasifier, while Figure 2 is an
isometric which shows the relative sizes of Coal
the different Transport Gasifier sections. Limestone
Loopseal
Steam, O2/Air J-leg
Figure 2 is the “as built in 1995” Transport
Reactor for the Power Systems
Development Facility showing the
combustion heat exchanger which is used Standpipe
only for combustion mode of operation. Startup
Burner
The combustion heat exchanger is currently O2/Air
Steam
still in place, but is disconnected. Two
major changes to the Transport Gasifier Standpipe
were the addition of a loop seal to the Solids
cyclone solids return to the standpipe and Figure 1 - Transport Gasifier
the addition of a lower mixing zone to the
bottom of the original mixing zone. Process
Gas Disengager
Cyclone
The KBR Transport Gasifier is based on
fluidized catalytic cracking (FCC) technology
developed in 1940, driven by the need to New Loop
Seal
produce gasoline during WWII, when location
commercial scale 13,000 b/d units were
successfully scaled up from a 100 b/d pilot Riser
unit (130/1 scale-up factor). Current
commercial FCC units have six foot diameter Coal
risers and capacities of 150,000 b/d. Sorbent
Air, Steam Standpipe
The Transport Gasifier consists of a mixing
Combustion Heat
zone, a riser, a disengager, a cyclone, a Mixing
Exchanger (out of
Zone
standpipe, a loopseal, and a J-leg. Steam and service)
air or oxygen are mixed together and New Lower Mixing Spent
introduced in the lower mixing zone (LMZ) Zone location Solids

while the fuel, sorbent, and additional air or Figure 2 - Transport Gasifier Isometric
oxygen and steam (if needed) are added in the
upper mixing zone. The steam and air or oxygen along with the fuel, sorbent and solids from the
standpipe are mixed together in the upper mixing zone. The upper mixing zone, located below the
riser, has a slightly larger diameter than the riser. The gas and solids move up the riser before
entering the disengager which removes larger particles by gravity separation. The majority of the
solids flow from the disengager into the standpipe and the remaining solids flow to the cyclone,
2
which removes most of the particles not collected by the disengager. The gas then exits the
Transport Gasifier and goes to the primary gas cooler and then to final particulate clean-up. The
solids collected by the disengager and cyclone are recycled back to the gasifier mixing zone
through the loopseal, standpipe and a J-leg. The solids circulation through the Transport Gasifier
is maintained by using recycled syngas or nitrogen as aerating gases. The Transport Gasifier
operating temperature is 1,500 to 1950ºF, depending on the fuel.

The fuel and sorbent are separately fed into the Transport Gasifier. Coal is ground to a nominal
average particle diameter between approximately 250 and 400 microns. Sorbent, if required, is
ground to a nominal average particle diameter of 10 to 100 microns. Limestone or dolomitic
sorbents are fed into the gasifier for sulfur capture. Sorbent is not added to the gasifier if no sulfur
capture is required in the gasifier. The Transport Gasifier produces coarse ash extracted from the
Transport Gasifier standpipe. The standpipe solid stream is cooled using a screw cooler and then
reduced in pressure in a lock hopper.

The Transport Gasifier is constructed of refractory lined pipe. The lining of reactor permits less
expensive metal to be used in the gasifier shell due to the lower temperature. Based on KBR
fluidized catalytic cracking unit design experience, the Transport Gasifier is designed without
expansion joints, using hangers and cans to permit the gasifier to increase in size as it heats up.
The Transport Gasifier operates at a high ratio of solids circulation to coal feed rates (between
20/1 and 50/1), which permits a rapid heating of the injected coal. The gasifier is designed so that
the standpipe level increases during operation, which requires that solids are continually removed
from the standpipe to maintain gasifier solids inventory. The solids circulation rate is controlled
by the solids standpipe level. Air or oxygen can be added to the gasifier at several different entry
points to set the gasifier temperature profile as desired. The gasifier riser velocity is between 20-
50 feet per second.

Advantages of KBR Transport Gasifier

The Transport Gasifier operates at moderate temperatures (1,500 to 1,950ºF) when compared to
many gasifiers which allows the use of more economical and longer lasting refractory (>14,000
hours). The Transport Gasifier has a simple, robust construction which is based on KBR’s
extensive fluidized bed catalytic cracking experience and is designed without expansion joints. In
high temperature service the use of expansion joints typically lead to sealing problems. The
gasifier has a high solids recirculation rate which results in excellent gas-solids contact in a highly
turbulent atmosphere and a low mass transfer resistance between gas and solids. It is particularly
well-suited for low-rank, high moisture, and high ash coals due to the low temperature operation
and high circulating solids rates. The gasifier has a small footprint due to its high heat release
which results in a high-coal throughput. The gasifier can operate in either air-blown or oxygen-
blown operating modes. KBR believes that air blown mode would be the best mode for power
generation and oxygen mode the best mode for chemical production.

Operation

The gasification test runs for the Transport Gasifier are summarized in Table 1.

3
 Table 1 - Test runs.
Test Fuel Air or Dates Hours
Run Oxygen
GCT1 PRB, Alabama Calumet mine Air September – 233
bituminous, Illinois #6 December 1999
GCT2 PRB Air April 2000 217
GCT3 PRB Air January 2001 183
GCT4 PRB Air March 2001 242
TC6 PRB Air July – September 2001 1,025
TC7 PRB, Alabama Calumet mine Air January – April 2002 442
bituminous
TC8 PRB Air, oxygen June 2002 364
TC9 SUFCO mine Upper Hiawatha Utah Air, oxygen September 2002 307
bituminous
TC10 PRB Air, oxygen November – 416
December 2002
TC11 Falkirk mine North Dakota lignite Air, oxygen April 2003 191
TC12 PRB Air, oxygen May – July 2003 733
TC13 PRB, Air, oxygen October – November 501
Freedom mine North Dakota lignite 2003
TC14 PRB Air, oxygen February 2004 214
TC15 PRB Air, oxygen April 2004 200
TC16 PRB, Air, oxygen July – August 2004 834
Freedom mine North Dakota lignite
TC17 PRB, Illinois Basin bituminous coal Air October – November 313
from Indiana 2004
TC18 PRB Air June – August 2005 1,342

Operation of the Transport Gasifier began in August 1996 with operations in combustion
operating mode. After 5,000 hours of combustion testing, shakedown in gasification mode began
in September 1999. The Transport Gasifier operated as an air blown gasifier through April 2002.
During this time, the gasifier accumulated over 2,300 hours on primarily Powder River Basin
(PRB) coal but also on Illinois #6 bituminous coal and Alabama Calumet mine bituminous.

Shortly after the beginning of gasification testing, it became apparent that operation could be
improved by increasing the solids collection in the gasifier. To this end, the dipleg below the
primary cyclone was replaced with a loop seal. Slight modifications were also made to the
primary cyclone and disengager, most notably lengthening the disengager barrel. The
modifications improved the solids collection which improved the carbon conversion and gas
heating value of the gasifier.

In late 2001, the mixing zone was modified below the J-leg to add the capability to add oxygen to
the gasifier. After one run testing the new configuration with air, the first oxygen blown testing
with the Transport Gasifier began in June 2002. Operations have been divided between air and
oxygen blown testing since this modification. There have been over 5,800 hours of gasification
since the addition of the LMZ with over 1,700 hours of this in oxygen blown mode.

The complete Transport Gasifier system is described in previous papers1, 2, 3, where testing barrier
filters in a particulate control devise, operating a pressurized syngas burner, and fuel cell testing
are described. Reference 1 also describes a syngas cleanup system installed to produce a syngas
suitable for use as a fuel cell feed. Reference 4 reviews and summarizes the testing of barrier
filters in the particulate collection device at the PSDF.
4
Gasifier Syngas Lower Heating Value

The syngas lower heating value (LHV) is calculated from the measured syngas constituents,
mainly from carbon monoxide, hydrogen, and methane concentrations. It is generally a function
of the fuel gasified, the mode of gasification (air blown or oxygen blown) and the amount of gas
used for fluidized bed aeration, instrument purges, and equipment purges (nitrogen, steam, or
recycled syngas). The minimum lower heating value required for commercial combustion
turbines is about 115 Btu/SCF.

Figure 3 gives the ranges of gasifier lower heating values that have been measured to date at the
PSDF. In air blown service Powder River Basin subbituminous had the highest lower heating
120
Air Blown Raw Lower Heating Values
100
Lower Heating Values, Btu/SCF

80

60

40

20 Oxygen Blown

0
PRB Utah Falkirk Freedom Indiana PRB Utah Falkirk Freedom
Bituminous Lignite Lignite Bituminous Bituminous Lignite Lignite

Figure 3 - Raw Lower Heating Values

values, followed by the Utah bituminous, Freedom lignite, Falkirk lignite, and the Indiana
bituminous. Since several of the fuels were only tested in one test campaign (Utah bituminous,
Falkirk lignite, and Indiana bituminous), it is likely that additional testing could product higher
lower heating values. For all of the coals, there was a significant increase in gas heating values
during oxygen blown operation. The raw heating values are lower than could be used in
commercial IGCC combustion turbines. At the PSDF, the Transport Gasifier raw syngas was
combusted in both a pressurized syngas burner and an atmospheric syngas combustor.

The PSDF Transport Gasifier produces syngas of a lower LHV than a commercially-sized gasifier
due to the use of nitrogen at the PSDF rather than recycle gas as in a commercial gasifier for
aeration and PCD backpulse cleaning. Since the PSDF Transport Gasifier is used for development
operation it has many more instruments than a commercial Transport Gasifier, which result in a
higher amount of purge gas used. The instruments required in a commercial gasifier will be the
same size as the PSDF, so the relative amount of purge gas per pound of coal gasifier will be less
than in the commercial plant. A commercially-sized gasifier also has a lower heat loss per pound
coal gasified when compared to the PSDF Transport Gasifier due to the higher gasifier surface
area / volume ratio at the PSDF compared to a commercially-sized gasifier. The projected
Transport Gasifier lower heating values were calculated from the raw PSDF Transport Gasifier
data assuming that recycled syngas or steam would be substituted for nitrogen as aeration gas and
that the Transport Gasifier heat loss was zero. The details of this calculation are given in Power
System Development Technical reports which are available on the PSDF web site5. Figure 4 gives
the ranges of the commercially projected Transport Gasifier lower heating values based on the raw
5
 300
Air Blown Oxygen Blown

250
Lower Heating Value, Btu/SCF Commercially Projected Gasifier
Lower Heating Values
200

150

100

50

0
PRB Utah Falkirk Freedom Indiana PRB Utah Falkirk Freedom
Bituminous Lignite Lignite Bituminous Bituminous Lignite Lignite

Figure 4 - Commercially Projected Gasifier Lower Heating Values

PSDF Transport Gasifier data. Again the PRB had the highest LHV followed by the Utah
bituminous, Falkirk lignite, Freedom lignite, and Indiana bituminous. The difference in order
between the raw and the commercially projected lower heating values is due to different amounts
of nitrogen used for aeration, equipment purges, and instrument purges at the PSDF for each fuel.
During the last test run, TC18, a recycle gas compressor was put in service to back out 1,500
pounds per hour of aeration nitrogen. This increased the raw syngas lower heating value by about
8 to 10%.

The commercial-sized gasifier is assumed to have a cold syngas cleanup system to remove the
sulfur (H2S, COS, CS2) and reduced nitrogen (NH3, HCN) compounds from the syngas. The cold
syngas cleanup system is located between the gasifier and the combustion gas turbine and cools
the syngas enough to reduce the moisture content to 1% moisture prior to combustion in the
combustion turbine. Figure 5 gives the commercially projected turbine inlet syngas lower heating
values for the five fuels tested at the PSDF. The heating values for the PRB and Utah bituminous
are well within the acceptable range for operation of a combustion turbine in air blown operation.
The Freedom lignite and Falkirk lignite are marginally in the range of a combustion turbine in air
blown operation, while the Indiana bituminous is not quite in the range of a combustion turbine.

Carbon Conversion

Carbon conversion is defined as the amount of fuel carbon that is gasified. The un-gasified carbon
leaves the gasification system with the gasification ash, either by the syngas particulate collection
device or from the standpipe. If the carbon conversion is not too high, the gasification ash is a low
grade fuel that could be combusted in conventional coal combustors to recover additional energy.
If the carbon conversion is extremely high, there is no economic benefit to combusting the ash and
the ash is disposed of in a landfill.

Figure 6 gives the ranges of carbon conversions for the fuels tested to date in the gasifier. Data
from TC14 was not included in the figure because erosion in the primary cyclone reduced the
solids collection efficiency resulting in lower carbon conversions. The lower rank coals, PRB and

6
 350
Air Blown Oxygen Blown
300
Lower Heating Value, Btu/SCF
Projected Turbine Inlet
Lower Heating Values
250

200

150

100

50

0
PRB Utah Falkirk Freedom Indiana PRB Utah Falkirk Freedom
Bituminous Lignite Lignite Bituminous Bituminous Lignite Lignite

Figure 5 - Projected Turbine Inlet Lower Heating Values

100 Falkirk Freedom Lignite
Powder River
Lignite
98 Basin Ex TC14

96
Utah
94 Bituminous
Carbon Conversion, %

92

90 Standard Low
Deviation Temp
Indiana
Ill. #5
88
Bit.
86

84
Carbon Conversions
82 TC06 to TC17

80
Air O2 Air O2 Air O2 Air O2 Air Air

Figure 6 - Carbon Conversions

lignite, have the highest carbon conversions. The higher ranked coals have progressively lower
carbon conversions.

The Freedom mine lignite tested to date consisted of separate seams of high sodium (5.5% Na2O
in the ash) and low sodium (1.7% Na2O in the ash). During the first test campaign with high
sodium Freedom lignite (TC13), temperatures were reduced to prevent problems from a low
melting point sodium-silicon eutectic. The reduced temperatures led to lower carbon conversions.
In a later test with the high sodium Freedom lignite operating conditions which resulted in

7
increasing temperature of operation by about 100ºF and increasing the carbon conversion by about
5%6. Figure 7 shows the effect of temperature on carbon conversion for Freedom lignite.

100
TC13 & TC16
Carbon Conversion
95
Freedom Lignite
Carbon Conversion, %

90

85

TC13
80
TC16

75

70
1,350 1,400 1,450 1,500 1,550 1,600 1,650 1,700 1,750
Mixing Zone Temperature, ºF
Figure 7 - Freedom Lignite Carbon Conversion and Temperature
Recent Additions to the Transport Gasifier System

During the testing and development of the Transport Gasifier, there have been numerous changes
to improve the operation of the system and to address potential scale-up problems. One recent
problem to have been addressed is the ash letdown system. At the PSDF, a screw cooler has been
used to cool the fine ash and a lock hopper system used to let the pressure down to atmospheric.
A commercial size screw cooler would be too large to be practical and there have been ongoing
problems with the lock hopper system. To address this, a Continuous Fine Ash Depressurization
(CFAD) system has been developed and installed. The CFAD system combines the cooling and
depressurization processes in a single system. The depressurized solids are then pneumatically
transported to an ash surge bin.

Future Plans

The PSDF will continue to see a diversity of research and testing areas in the future. A coarse ash
cooling and depressurization system, similar to the CFAD system being tested with fine ash, will
be installed later this year. There is ongoing work to improve coal feeder systems which may
include tests of a Stamet pump. Plans are underway for biomass testing in the Transport Gasifier.
The range of fuels tested in the gasifier will continue to expand.

Economic Studies

A series of conceptual commercial plant design were completed by SCS to guide future tests and
commercialization of the technologies at the PSDF7. Four Transport Gasifier combined cycles
cases were developed to investigate the relative costs and benefits of oxygen-blown or air-blown
gasification and of stack gas or syngas cleanup. Initial results of this study indicate that for the
Transport Gasifier it is more economical to use air-blown mode of operation rather than oxygen
blown for power production. The results of this study were then put on the same basis as a recent
EPRI study which compared the cost of electricity (COE) between sub-critical pulverized coal
8
combustion, super critical pulverized coal combustion, ultra-super critical pulverized coal
combustion, Shell Gasifier gasification, Conoco Gasifier gasification, and air-blown Transport
Gasifier gasification. The Transport Gasifier gasification economics are based on the Nth plant
design. The results of this study are given in Figure 8 where is shown that the Nth Transport
Gasifier has the lowest levelized cost of electricity.
Comparison of 500 MW Coal Power Plants
(2003$, Sub bituminous Coal @$1.00/MMBtu, 85% capacity factor)

5.0 10,000
Levelized COE (Cents/kWh)

4.5 4.7 4.8 9,000

4.0 8,000

3.8 3.8 3.8

3.5 3.6
7,000

3.0 6,000

Btu/kWh
2.5 5,000
9740 9240 9100 8810 9630 8320
4,000
2.0 35.0 36.9 37.5 38.7 35.4 41.0
% % % % % %
3,000
1.5
2,000
1.0
1,000
0.5
0
0.0
Sub-Critical SC-PC USC-PC Shell Conoco NNthth TRIG
Transport
Heatrate Pulverized Coal Gasification
Fuel
O&M
Capital - Transport gasifier cost from SCS studies. Other costs adjusted to SE location from an EPRI report titled:
2 Capture - 2003
"Updated Cost and Performance Estimates for Clean Coal Technologies including CO

Figure 8 – Levelized COE – 500 MW Power Plant

Orlando Gasification Project

The Transport Gasifier has also been selected to be the basis of an IGCC plant at the Stanton
Energy Station Orlando, Florida as part of round 2 of the DOE’s Clean Coal Power Initiative.
The partners in the project are Orlando Public Utilities, Southern Company, and Kellogg, Brown
& Root. The output of the project will be 285 to 330 MW using subbituminous Powder River
Basin coal (0.25 % S). The Transport Gasifier will be operated in air blown mode using a dry coal
feed system (lock hoppers). Particulate control will be by barrier filters. Gasification ash will be
disposed by either on-site combustion or landfill. Sulfur control will be cold gas cleanup
producing sulfur for sales. There will be an ammonia recovery by sour water stripping. The
recovered ammonia will be used in the selective catalytic reduction system after the combustion
turbine.

Currently the project team is negotiating a contract with the DOE. Design is scheduled to begin in
October 2005, construction is scheduled to begin in December, 2007, and demonstration is
scheduled to begin in June 2010.

Conclusions

The Transport Gasifier in Wilsonville has been successfully operated for over 7,700 hours in
gasification in both air and oxygen blown operations. Testing of lignite and subbituminous coals
has shown that low rank fuels can be successfully processed with sufficient syngas heating value
and carbon conversion. Data and operating experience from the PSDF has lead to the commercial-
9
sized Orlando Gasification Project. The PSDF will continue to test and demonstrate components
of clean coal technology in an integrated environment.

References

1. Brandon M. Davis, Roxann Leonard, P. Vimalchand, Guohai Liu, Peter V. Smith, Ron
Breault, "Operation of the PSDF Transport Gasifier", Twenty-Second Annual Pittsburgh Coal
Conference, Pittsburgh, PA, September 12-15, 2005.
2. Brandon M. Davis, Oliver Davies, J. Matthew Nelson, X.Guan, Roxann F. Leonard, Guohai
Liu, W. Peng, P. Vimalchand, Peter V. Smith, James Longanbach, “Gasification of Low
Rank Coals at the PSDF”, Nineteenth Western Fuels Symposium, Billings, MT, October 12-
14, 2004.
3. Ron W. Breault, “Power Systems Development Facility Transport Gasifier Operations”, 2005
Clearwater Coal Conference, Clearwater, FL, April 17 – 21, 2005.
4. Xiaofeng Guan, Ben Gardener, Ruth Ann Martin, Jack Spain, “Demonstration of Hot Gas
Filtration in Advanced Coal Gasification System” 6th International Symposium on Gas
Cleaning at High Temperatures”, Osaka, Japan, October 20-22, 2005.
5. PSDF Technical Progress Reports, http://psdf.southernco.com/.
6. Peng, WanWang, Matt Nelson, Roxann Leonard, Guohai Liu, P. Vimalchand, Robert Dahlin,
“High-Sodium Lignite Gasification with the PSDF Transport Gasifier”, Twenty-Second
Annual Pittsburgh Coal Conference, Pittsburgh, PA, September 12-15, 2005.
7. Luke H. Rogers, Alexander K Bonsu, Joseph D Eiland, Benjamin F. Gardener, Charles A.
Powell, George S. Booras, Ronald W. Breault, Nicola Salazar, “Power From PRB – Four
Conceptual IGCC Plant Designs Using the Transport Gasifier”, Twenty-Second Annual
Pittsburgh Coal Conference, Pittsburgh, PA, September 12-15, 2005.

10