CATALYTIC
APPLICABILITY STUDY
COAL GASIFICATION PROCESS
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APPLICABILITY STUDY
COAL GASIFICATION PROCESS
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FINAL REPORT
APPLICABILITY STUDY
'. COAL GASIFICATION PROCESS
CONTRACT NO. 68-02-0241
ENVIRONMENTAL PROTECTION AGENCY
Mi.\R.Q-i 1 97 2
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EPA CONTRACT NO. 68-02-0241 - TASK NO. 8
CATAlYTIC PROJECT NO. 41937
BY
L. K. JAIN
T. J. HIXSON
MAACH 1972
PREPARED BY
CATALYTIC, INC.
1515 MOCKINGBIRD LANE
CHARLOTTE, NORTH CAROLINA 28209
PREPARED FOR
DIVISION OF CONTROL SYSTEMS
OFFICE OF AIR PROGRAMS
ENVI RONt-1ENT Al PROTECT! ON AGENCY
RESEARCH TRIANGLE PARK
NORTH CAROLINA
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ACKNOWLEDGEMENTS
Many individuals and several organizations have been helpful in
developing this study; for these contributions Catalytic, Inc. ex-
tends its
sincere gratitude.
The following individuals. deserve
particular credit for their contributions:
Applied Technology Corporation
Mr. J. Karnavas
.. Mr. P. LaRosa
! .
Alleghany Power Company
Mr. W. Kress
i .
Mr. H. Micala
Babcock and Wilcox Company
Mr. D. O'Brien
Carolina Power and Light Company
I
,
I
Duke Power Company
Mr. J. Sell
Mr. D. Voyles
National Academy of Science
Mr. R. Crozier
I
I Office of Coal Research
- .
Mr. N. Cochran
Tennessee Valley Authority
Mr. R. Haskins
Mr. U. Zitzon
Getty Oil Company
!
Mr. C. Phillips
Delmarva Power Company
Mr. H. Hoen
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.
.
TABLE OF CONTENTS
Page
INTRODUCTION................................................1
DESCRIPTION OF PROCESS......................................l
DISCUSSION..................................................2
Int'roduction. . . .. . .. .. e.. .. ,. .. ...... ... . .. .... .... .... .. ..2
Cost Aspects.........................;.....................3
Space Requirement for the Process.........................4
Type of Fuel........................... '. . . . . . . . . . . . . . . . . . .6
Operational, Maintenance and Safety Aspects...............7
By-Product
Disposal. . . . . . 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Standby Fuel Requirements...............................8
Turndown Capabilities of the Combustion.................8
Safety Aspects of the
Process. . . . . . . . . . . . . . . . . . . . . . . . . . .8
Scheduled Maintenance and "Down-Time"..................lO
Design
Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
APPENDIX A.
CONCEPTUAL DESIGN OF COMBUSTOR.~..............l3
APPENDIX B.
ATC COAL COMBUSTION PROCESS...................l4
APPENDIX C.
ESTIMATED COST FOR COMBUSTION PROCESS.........lS
APPENDIX D.
CAPITAL COSTS FOR COAL GASIFICATION/SULFUR
REMOVAL PROCESSES............................l6
APPENDIX E.
ATC PROCESS INSTALLED CAPACITY VS. CAPITAL
COSTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
APPENDIX F.
ATC PROCESS INSTALLED CAPACITY VS. COST/KW....18
APPENDIX G.
EXISTING AND PLANNED POWER GENERATING
FACILITIES................................. '. .19
REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
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INTRODUCTION
The Environmental Protection Agency has the task of developing tech-
nology for a national program for control of air pollution.
One aspect
of this program is advancement of technology in the boiler industry so
that emission control and compliance with state and federal regulations
can be met with a minimum expenditure of time and money.
The objective of this study is to determine the applicability of
the Applied Technology Corporation (ATC) Coal Gasification Process to
electric utility and industrial boiler facilities for new installa-
tions and for the "retrofit" of existing installations.
Specific ob-
jectives are evaluation of the process with respect to cost, space
limitations and operational, maintenance and safety aspects.
In addi-
tion, a I number of technical difficulties and unresolved problems are
outli~ed.
The use of the ATC Coal Gasification Process may offer potential
capital cost savings, compared to existing methods of sulfur removal
in the combustion of coal, markets for ca~ing-type high sulfur coals
I
, .
(10,000 BTU/Lb. or less) and a method of reducing particulate emis-
sions by converting coal to a cleaner fuel. .
DESCRIPTION OF PROCESS
The process under study consists basically of a cylindrical-shaped,
refractory-lined metal structure, termed a combustor (Appendix A), to
convert pulverized coal into a "low BTU" fuel gas.
The combustor con-
tains a mass of molten iron into which the crushed coal is pneumati-
cally injected by means of a lance.
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DESCRIPTION OF PROCESS
(Continued)
Upon entering the bath, volatile components in the coal are sepa-
rated from soluble portions, chiefly consisting of carbon (relatively
low solubility) and sulfur (relatively high affinity for iron).
The
high affinity of sulfur for iron prevents formation of significant
amounts of sulfur dioxide.
The dissolved carbon is oxidized to car-
bon monoxide by means of air injection through an additional lance,
while dissolved sulfur is extracted by continuous injection and .re-
mova1 of a limestone/slag mixture.
Iron is a by-product of the pro-
cess through decomposition of pyritic sulfur compounds present in
the coal.
The prime product is a high temperature (25000F - 27000F) gas
rich in carbon monoxide and hydrogen, with approximately 175 BTUt
Std. Cu. Ft. available heat of combustion.
Preliminary data indi-
cates that negligible amounts of particulate matter are found in
the off-gas.
The sulfur-containing slag is treated by a Claus pro-
cess to produce elemental sulfur as a product (Appendix B).
DISCUSSION
Introduction
The subject process was studied based on data supplied by
Applied Technology Corporation and discussions with various
firms having a direct interest in the process, including uti-
1ity companies, boiler manufacturers and related industries.
Conclusions developed during this study are based only on pre-
1iminary technical and cost information without actual pilot
tests and are subject to this qualification.
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(Continued)
. DISCUSSION
Cost Aspects
Preliminary fixed capital cost requirements incorporating this
(1)
process in a 1,000 megawatt new power installation are $23,330,000
(1980 basis - Appendix C).
This cost relates favorably to costs
i
I
of comparable processes under
(2)
power plants
consideration for 1,000 megawatt
(Appendix D).
Scaled-down costs for the ATC pro-
cess for new installations smaller than 1,000 megawatts were devel-
. -
oped from the base data and application of a 0.6 power scale factor
(Appendix E).
A graphical relation of capital cost per kilowatt
versus size of installation indicates a significant increase in
unit cost as the size of the installation is decreased below 300
megawatts (Appendix F). Since existing flue gas desu1furization
(3)
processes are available at approximately $40/KW , the indicated
minimum size, economically attractive installation for the ATC
process, is 250 megawatts.
This conclusion eliminates economic
application of the ATC process in all industrial applications
and 55 percent of existing coal-fired steam electric plants.
The process theoretically is economically feasible for "re-
trofit" plants in 45 percent of the existing (1971) steam elec-
tric units (188 of 419, representing 83 percent of present, in-
stalled capacity of coal burning units) and 100 percent of the
planned (1971-1980) new plants (91 units) of 240 megawatts size
(4)
or greater
(Appendix G).
Additional possible favorable cost aspects which apply to use
of the ATC process in new facilities are:
-3-
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(Continued)
'DISCUSSION
Cost Aspects
(Continued)
1.
Cost savings by the total or partial elimination of pulver-
izers. since the process has capabilities of handling up
to 200 mesh - 1/4" coal.
2.
Cost savings by the use of shorter boiler exhaust stacks.
since the emission of sulfur dioxide is minimal.
3.
Cost savings by the installation of smaller size boilers
for the combustion of the gasified coal. assuming no
i standby fuel requirements.
4.
Possible cost savings from elimination of particulate
emission equipment.
Until proven that the process is economical and the potential
cost saving aspects are favorable. the users indicate that the
process is seemingly feasible for 250 MW or larger new boilers.
Because of the comparative individuality with respect to boiler
design and plant layout of existing coal-fired steam electric plants.
it is not possible to assess rigorously the capital costs required
for retrofitting the process to an existing installation without
in~depth engineering studies of each facility.
Similarly. the fac-
tors affecting costs concerning the chronological age of the,exis-
ting boilers are sufficiently diverse for different boilers that
a specific age limitation was not indicated by the potential users.
Space Requirement for the Process
A 1.000 megawatt electric utility plant. using the ATC process
as a fuel source. will require typically three combustors. each
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DISCUSSION
(Continued)
$pace Requirement for the Process
(Continued)
approximately 38' in diameter.
The combustors will operate con-
tinuously with one combustor serving, as a spare.
Scaledown for smaller size installations is a function of in-
stallation capacity, coal solubility rate and off-gas velocity.
The limiting factors in de terming a minimum practical combustor
size are heat loss per pound of coal converted and area for stabi-
lizing reaction turbulence.
Both heat loss and reactor turbulence
increase proportionately with decrease in combustor diameter.
No
effo~t is made at this time to determine quantitatively the prac-
tical minimum combustor diameter.
The ATC bench-scale application
is approximately 3' in diameter.
Suggested possible locations for the combustor installation
with respect to the boilers in a "retrofit" plant are:
1.
In place of existing pulverizers, assuming discontinua-
tion of the pulverizing requirement.
2.
On the opposite side of the steam boilers from the pu1-
verizers, if the pulverizers are required.
3.
In between two boilers.
4.
In a remote area within 100' of the boilers (probably out-
side building at grade level).
5. , In place of existing electrostatic precipitators or equi-
valent particulate control devices, assuming no particu-
late emission problems for commercial units.
From a random sampling of power industry personnel, it appears
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DISCUSSION
(Continued)
Space Requireme~t for the Process
(Continued)
on a preliminary basis that one-half of "retrofit" plants will have
no space problem for locating combustors, whereas the other half
will require extensive pre-engineering to determine a 'suitable loca-
tion.
Direct connection of combustors to boilers for "retrofit"
plants is probably impractical.
A significant difficulty in "retrofit" application of the pro-
cess is installation of very large (approximately 30' diameter,
or equivalent, for a 1,000 megawatt) off-gas ducts from the com-
I
bustors to the boilers, with manifolding between combustors.
Type of Fuel
The process can convert any coal, except lignite or similar
coal containing a high percentage of moisture, and permits a
possible market for low cost, high sulfur, high ash coal.
High
moisture content tends to use heat from the iron bath in convert-
ing water into vapor and to lower the gas output.
Excessive water
vapor could possibly create an explosion hazard.
High moisture
content coals will have to be pre-dried before use, however, a
specific moisture content limitation has not as yet been defined.
The process can also use petroleum coke to produce "low BTU"
gas.
Petroleum coke is high in sulfur content and has limited
Most refineries (source of petroleum coke) have
use at present.
either on-site steam and power generation facilities or are 10-
cated close to a utility steam and power supply.
Additionally,
refineries usually have Claus sulfur recovery units within plant
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J;>ISCUSSION
(Continued)
Type of Fuel
(Continued)
limits and a developed sulfur market.
.(5)
According to 1971 data
39,000 tons per day of petroleum coke are generated in the United
States, capable of producing 5,000 megawatts of power.
Potential
application of the ATC process to converting petroleum coke con-
tributes to its attractiveness.
Operational, Maintenance and Safety Aspects
By-Products Disposal
The three by-products produced by the ATC process are e1e-
mental sulfur, desu1furized slag and granulated iron.
In the
cases of sulfur and iron, the chief factors affecting disposal
are market price and location.
No significant disposal problems
are foreseen at this time.
However, no credit in the developed
economic data is taken relative to these marketable by-products.
The slag exhibits good road construction properties.
How-
ever, due to increased quantity compared to fly ash quantity
from a conventional coal burning station, some additional dis-
posal expenditures for slag will be required.
It is apparent
that sulfur-laden slag will not be an acceptable landfill mate-
rial over a long period of time, because of the potential re-
lease of hydrogen sulfide through hydrolysis.
The by-product slag from the combustor will be 30 percent
higher in weight than equivalent fly ash and will have much
higher bulk density.
Additionally, it is possible that trans-
portation of slag as a slurry will be more difficult than cur-
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DISCUSSION
(Continued)
Operational, Maintenance and Safety "Aspects
(Continued)
By-Products Disposal
(Continued)
rent means of pumping fly ash slurries.
Hence. it is possible
th4t the by-products will require an increased material handling
expenditure over current conventional plants.
The possible in-
crease in material handling cost is not included in the cost es-
timate (Appendix C).
StandbY Fuel Requirements
Standby fuel is not required if an application which uses a
~nimum of two combustors, with one acting as spare, is employed.
~owever, if the spare combustor concept is not used, a standby
fuel source is mandatory for continuous plant operation. It is
I "
I;
likely that, because of logistical problems involved in obtain-
iug large amounts of fuel on short notice, the standby fuel ap-
proach is not feasible.
Turndown Capabilities of the Combustor
The reported turndown capability of the process is 33:1, there-
by providing no overall boiler system turndown restriction.
Safety Aspects of the Process
A number of potential safety hazards are inherent in the pro-
cess, but none are considered insurmountable by various power
plant management personnel.
The most significant potential hazard is the location of a
large amount of molten iron at localized high temperatures with-
in the boiler area and its potential for leakage from the com-
-8-
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DISCUSSION
(Continued)
Operational~ Maintenance and Safety Aspects
(Continued)
Safety Aspects of the Process
(Continued)
bustor.
This hazard ca~ be reduced by use of steel production
, .
safety procedures for personnel protection and construction of
dikes or similar features to contain the molten iron in the event
of leakage from the comb~stor.
A second potential s~fety hazard i~ the possible introduction
of water into the molten iron and the resulting high~ instantan-
eo us partial pressure created by high process temperatures.
Two
possible sources of water introduction are, as follows:
1.
Large amounts of water resulting from boiler tube failure.
This hazard can be reduced by proper design of the off-gas
ducting to prevent water flow into the combustor.
2.
Water-cooled lance failure, with potential release of water
beneath the molten iron-slag interface.
Power company re-
presentatives have expressed the opinion that, because of
this extremely hazardous situation, some other means of
lance cooling must be devised before power stationapplica-
tion is feasible.
Present ATC bench-scale operation uses
water-cooled lances.
A third potential safety hazard is the explosive nature of the
combustor off-gases.
It is concluded that safety procedures com-
parable to those used in the handling of natural gas will be ade-
quate to protect against this hazard.
-9-
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DISCUSSION
(Continued)
Operational, Maintenance and Safety Aspects
Scheduled Maintenance and "Down-Time"
(Continued)
The gasification system can be designed to provide non-inter-
ruptible service by the use of a minimum of two combustor systems,
with one system in operation at all times.
The spare combustor
may be refitted during its "do~-time".
Combustors should be
periodically switched to the sparing operation to permit servic-
ing.
Minimum design service life for any component of the com-
bustor system should be one year for operational and maintenance
feasibility.
Design Problems I
Listed below are a series of unresolved problems with respect to
design of a workable installation incorporating the ATC Coal Gasifi-
cation process:
1.
The negligibility of particulate emissions from the process
for commercial installations has not definitely been eatab-
lished.
Significant emissions in a "retrofit" plant, because
of possible scale build-up on the boiler tubes and possible
resulting tube abrasion, could shorten boiler life.
In add i-
tion, significant particulate emissions could require installa-
tion of an electrostatic precipitator or other cleanup device,
not presently considered in existing cost data.
2.
Expansion, manifolding and isolation of 20' - 30' diameter
combustor off-gas ducts, or small ducts of equivalent cross-
sectional area, represent a major design effort.
Refractory
-10-
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DISCUSSION
(Continued)
(Continued)
Design Problems
(Continued)
2.
lining and/or water cooling are apparently mandatory.
3.
No developmental work has been conducted to determine the
type of refractory lining to be used in the combustors and
ducting, sufficient to provide a minimum service life of
one year.
4.
The feasibility of transporting 25000F - 27000F process off-
gas has not been determined.
Associated ducting costs, or
potential heat exchange requirements with boiler combustion
air, may be a significant cost factor in a "retrofit" plant.
5.
At present, no known design exists for a lance which will
withstand the combustor service conditions.
The present in-
dication is that a lance cooled by liquid metal, oil or
material other than water must be ~sed.
In addition, no
information is available to relate the number of lances re-
qui red as a function of combustor size.
6.
No information is presently available regarding either flame
temperature or NOx emissions from the combustion of the pro-
cess off-gas.
It is possible that significant amounts of NOx
may be formed if the pressure in the system must be raised to
enable process off-gas flow to the boiler combustion chamber.
7.
No data are presently available on the "weathering" effect
of non-desulfurized slag.
Long-term possibilities of this
effect may be formation of hydrogen sulfide or leaching out
of sulfuric and/or sulfurous acids.
-11-
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DISCUSSION
(Continued)
Design Problems
(Continued)
8.. No data are available on control techniques for continuous
system operation.
Present ATC maximum operability experi-
ence is 24 hours.
9.
Conversion from an existing coal-fired to a gas-fired boiler
in a "retrofit" operation may cause a loss of thermal effi-
ciency.
It may be necessary to evaluate each particular
boiler design individually to the process effect in effi-
ciency.
-12-
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APPENDri k'.
CONCEPTUAL DESIGN OF COMBUSTOR
"ATC:. COAL COMBUSTION PROCESS (1)
.lit
~L 1AKCI
\
LIMlSTOIfI-A1R tAICI
/
CClCBUSTOlt orrGAS
....
.. .
....
,:::il\:r:
...
.".".".".
"..
~
-13-
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All
AIR
@
AIR CamutSsoa
I
....
~
I
cau SLAG- LIMESTONE
BOILER D
@
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APPENDIX C
ESTIMATED FIXED CAPITAL REQUIREMENT
TWO-STAGE COAL COMBUSTION ~19CESS
1000 MW POWER PLANT
EQUIPMENT COMPLEX
$MK
Combustor
1.41
Coal Preparation
2.25
Flux/Slag Preparation
0.42
Desulfurization
0.37
Air Preparation
2.59
1.
Total Purchased Equipment Cost
7.04
Installation, Piping, Electrical
Instrumentation, Utilities
(70% of 1)
4.92
2.
Physical Plant Costs
11.96
Engineering and Construction
(30% of 2)
3.59
3.
Direct Plant Cost
15.55
Contingency (10% of 3)
Contractor's Fee (6% of 3)
1.56
0.93
4.
TOTAL
18.04
.Esca1ation to 1980 (14.75% of 4)
2.66
5.
TOTAL
20.70
6.
Interest During Construction
(12.6% of 5)
TOTAL FIXED CAPITAL (1980)
23.33
2.63
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APPENDIX D
Capital Costs for Coal Gasification/Sulfur Removal Processes.
I' ., 1 1 I I .1
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20
80
100
40
60
Fixed Capital Cost $/KW
Cost based on 1000 MW
. (nominal) plant
-------
Appendix E
ATC Coal Gasification Process
Insta11e4 Capacity vs. Capital Cost
-
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.-I
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600
400
800
Installed Capacity Megawatts
1000
-------
150
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100- 200- 3QO- 400~ 500- 600- 700- 800- 900- 1000- 1100- 1200- 1300-
199 299 399 499 599 699 799 899 999 1099 1199 1299 1399 . ~ 1~00
Insta11~d Capacity
APPENDIX G
ExistingandP1anned Power Generating Fac:i1ities
~ 100MW
-19..,
-------
(1)
REFERENCES
Pe1czarski, E. A., P. LaRosa. Two Stage Combustion
Process. Applied Technology Corporation. Table II.
December 2, 1971
(2)
Robson, F. L. et a1. Technology and Economic Feasi-
bility of Advanced Power Cycles and Methods of Pro-
ducing Non-Polluting Fuels for Utility Power Stations.
United Aircraft Research Laboratories. December 1970.
38-84 p.
(3)
(4)
Ibid, 38-84 p.
Rowe, W. D.
The Mitre Corporation.
December 1971.
(5)
Cantrell, Ailleen. Annual Refinery Survey. 011 and
Gas Journal. Volume 69, No. 12. March 22, 1971.
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