New Sources of Oil & Gas. Gases from Coal; Liquid Fuels from Coal, Shale, Tar Sands, and Heavy Oil Sources

108 Pages·1982·2.48 MB·English

by  S. S. Penner, S B. Alpert and V Bendanillo (Auth.)

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NEW SOURCES
OF OIL & GAS
Gases from Coal; Liquid Fuels from Coal, Shale
Tar Sands, and Heavy Oil Sources
by
S S Penner, S Β Alpert, V Bendanillo, S W Benson, W S Bergen,
F W Camp, J Clardy, J Deutch, L Ε Furlong, J M Hopkins, A Ε Kelley,
F Leder, L Lees, R R Lessard, A Ε Lewis, F X Mayer, A G Oblad,
Ε Reichl, J Ross, R Ρ Sieg, A M Squires, J R Thomas, M A Weiss,
Ρ Β Weisz, and D D Whitehurst
(Members of the U.S. DOE Fossil Energy Research Working Group, FERWG, 1978-82)
PERGAMON PRESS
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First edition 1982
Library of Congress Cataloging in Publication Data
Main entry under title:
New sources of oil & gas.
"Previously published in Energy, the
international journal, vol. 5, no. 11, vol. 6,
no. 12, and vol. 7"—Verso t.p.
1. Synthetic fuels—Addresses, essays,
lectures. I. Penner, S. S. II. U. S. DOE
Fossil Energy Research Working Group.
III. Title: New sources of oil and gas.
TP360.N48 1982 662.66 82-10126
ISBN 0 08 029335 2
Previously published in Energy, the International
Journal, Vol. 5, No. 11, Vol. 6, No. 12 and Vol. 7.
Printed in Great Britain by A. Wheat on & Co. Ltd., Exeter
PREFACE
In 1978, senior officials of the U. S. Department of Energy established a joint industry-
university-government committee, known as the Fossil Energy Research Working Group
(FERWG). FERWG was asked to perform a detailed evaluation of research and develop-
ment issues relating to new sources of oil and gas from coal, oil shale, heavy oil sources,
and tar sands. Abbreviated versions of the lengthy FERWG reports have been published
previously in Energy, the International Journal. These papers are here reprinted because
they provide a coherent and up-to-date account of developing fossil-fuel technologies that
are likely to represent the world's primary energy sources for a very long time to come.
It is our hope that the FERWG studies will be of interest to industry executives and
engineers, to governmental officials and planners, as well as to university scientists and
engineers.
S. S. PENNER
Chairman, FERWG
V
RESEARCH NEEDS FOR COAL GASIFICATION
AND COAL LIQUEFACTION!
S. S. PENNER,Î S. Β. ALPERT, V. BENDANILLO, J. CLARDY, L. E. FURLONG,
F. LEDER, L. LEES, E. REICHL, J. Ross, R. P. SIEG,
A. M. SQUIRES, and J. THOMAS
^Energy Center and Department of Applied Mechanics and Engineering Sciences,
University of California, San Diego, La Jolla, CA 92093, U.S.A.
Abstract—We describe essential features of developing coal-gasification and coal-liquefaction
technologies and summarize the current development status and important R&D needs for these
processes.
1. INTRODUCTION
The Fossil Energy Research Working Group (FERWG), at the request of J. M. Deutch
(now Under Secretary of DOE), E. Frieman (now Director, Office of Energy Research)
and G. Fumich, Jr. (now Assistant Secretary for Fossil Energy), has reviewed and evalu-
ated DOE-funded coal-gasification and coal-liquefaction technologies. These studies
were performed in order to provide an independent assessment of critical research areas
that affect the long-term development of these important coal-conversion processes. The
findings of FERWG have been published in two extensive documents 1'2 from which this
paper has been abstracted.
Members of FERWG performed extensive schedules of site visits to process-develop-
ment units and facilities, as well as to university and DOE laboratories, in order to
familiarize themselves with current and planned research programs. Site-visit reports and
evaluations, with emphasis on identified process and fundamental research needs, were
prepared by participating FERWG members after each site visit.
FERWG members held numerous discussions with the Under Secretary of DOE, the
Director of the Office of Energy Research, the Assistant Secretary for Fossil Energy,
members of their staffs, DOE program managers, directors of laboratories and develop-
ment engineers who are involved in coal-gasification and in coal-liquefaction research
and development (R&D) in both industrial and governmental organizations, and uni-
jThis paper is based on studies performed by the Fossil Energy Research Working Group (FERWG) of the
Department of Energy dealing with coal gasification (under DOE Contract No. ER-78-C-01-6335, 1978-79,
with the Mitre Corporation) and coal liquefaction (under DOE Contract No. DE-AC01 ER 10007, 1979-80,
with the University of California). The following members of FERWG participated in all of the studies: S. B.
Alpert (Technical Director of Advanced Fuels, Advanced Fossil Power System, Electric Power Research Insti-
tute, P.O. Box 10412, Palo Alto, CA 94303), L. E. Furlong (Director, Coal Research Program, Exxon Research
and Engineering Co., P.O. Box 4255, Baytown, TX 77520), S. S. Penner, Chairman (Director, Energy Center,
B-010, University of California, San Diego, La Jolla, CA 92093), Ε. Reichl (President, Conoco Coal Develop-
ment Company, High Ridge Park, Stamford, CT 06904), J. Ross (Department of Chemistry, Stanford Univer-
sity, Stanford, CA 94305), R. P. Sieg (Manager, Synthetic Fuel Division, Chevron Research Company, P.O. Box
1627, Richmond, CA 94802), A. M. Squires (Department of Chemical Engineering, Virginia Polytechnic
Institute and State University, Blacksburg, VA 24061), and J. Thomas (President, Chevron Research Company,
P.O. Box 1627, Richmond, CA 94802); V. Bendanillo (Manager, Fossil Energy Projects, Gas Research Institute,
10 West 35th Street, Chicago, IL 60616) and L. Lees (Environmental Engineering, California Institute of
Technology, 1201 East California Blvd., Pasadena, CA 91109) were members of FERWG dealing with coal
gasification and J. Clardy (Department of Chemistry, Cornell University, Ithaca, NY 14853) and F. Leder
(Director, Exploratory and New Ventures Research, Occidental Research Corporation, P.O. Box 19601, Irvine,
CA 92713) were members of FERWG working on coal liquefaction. The advice of very many active workers in
the fields of coal utilization, and especially of I. Wender, is gratefully acknowledged. Willard E. Fraize of the
Mitre Corporation made essential contributions to the FERWG studies on coal gasification.
1
2 S. S. PI;NNLR et ai
versity-based scientists and engineers who perform research related to coal-liquefaction
studies. In addition, FERWG received written comments from experts on coal gasifica-
tion and liquefaction.
2. COAL GASIFICATION
Coal-gasification technologies and processes have been developed and commercia-
lized for a long time. Although the proliferation of named and identified technologies is
very large (a National Research Council Report 3 identifies 37 individual "representative
processes" among perhaps 180 gasification technologies), the number of generically dif-
ferent, aboveground gasifiers is closer to 7 (e.g. fixed-bed gasifiers that produce dry ash or
slag; fluidized-bed gasifiers that produce dry or agglomerating ash; entrained-flow gasi-
fiers that yield dry ash or slag during primary gasification; and molten-bath gasifiers).
2.1 Introduction
The coal gasification industry has been well established for some time, and the large
body of accumulated knowledge and experience must be taken into account, relearned if
necessary, appreciated, and applied. Numerous differing gasification techniques are
necessary to produce the desired variety of products, including low-, medium-, and high-
Btu gas, from the wide range of available coal feedstocks. The needs of the electric power
industry for gasification products are different from those of the gas utilities and these, in
turn, differ from the requirements for production of, for example, chemical feedstocks,
industrial power, and steam generation. The steady increase in environmental regulations
has brought about the need for gas cleanup processes.
Coal gasification is a mature technology but it is not now economically competitive,
and potentially attractive alternatives to the Lurgi gasifier have been beset by operational
difficulties of every conceivable variety. There have been "surprises, 11 and, according to
W. G. Schlinger (manager of the Texaco entrained, downflow coal-gasification process),
the absence of "surprises11 on scaling would itself be "surprising.11
Coal-gasification technologies are very sophisticated. Proposals for technological im-
plementation clearly lead understanding and mundane operational problems may reflect
gaps in basic understanding. For example, clinker formation in pilot-scale gasifiers may
perhaps be elucidated through research on (i) the mechanisms and rates of nucleation
during gas-phase combustion; (ii) forces between tiny particles, agglomeration, and
growth kinetics on collisions between particles; (iii) surface forces in nonuniform struc-
tures of carbon and hydrogen; (iv) surface physics; and (v) surface kinetics. Coal scientists
have had little impact on the development programs in the past, partly because the real
problems are "dirty11, are extraordinarily complex, and do not lend themselves to ready
modeling or useful first-order descriptions.
The U.S. Bureau of Mines Mineral Industry Survey of 1 January 1974 yielded a
demonstrated coal reserve base of 437 χ 10 9 tons. This number must be multiplied by a
fraction recoverable for use (usually taken to be 0.5) and also reduced somewhat to
correct low-Btu coals to some standard (e.g. 25 χ 10 6Btu/ton). Thus, demonstrated re-
coverable coal reserves are about 200 χ 10 9tons, worth trillions of 1979 dollars. The
ultimately recoverable resource, according to P. Averitt (1967), may be as large as
3.2 χ 1012tons (not including Alaskan resources). At reasonable costing, the value of
these ultimately available resources may exceed $50 trillion (1978 dollars), of which
perhaps one-third (S15—$20 trillion) may well become attributable to coal gasification
processing.
General background information, thermodynamic analyses, and descriptive material
on selected process configurations appear in textbooks. 4'5
2.2 Applications of coal-gasification technologies
There are three principal areas for application of coal-gasification products. The gas-
distribution companies require high-Btu syngas (SNG) that may be freely intermingled
Coal gasification and coal liquefaction 3
with natural gas. Electric utilities and industrial users of gaseous fuel generally find
low-Btu gas most cost effective. The chemical process industries prefer mixtures of car-
bon monoxide (CO) and hydrogen (H ), as contained in medium-Btu gas.
2
The user-oriented presentations in this chapter describe the initial process-related
R&D needs of the coal-gasification industries.
2.2.1 High-Btu gas for the gas industry. The main interest of the gas utilities in coal
gasification is to produce high-Btu, pipeline-quality SNG to augment the available sup-
plies of natural gas. Current cost projections (1976-78) for a 250 billion Btu per day
(Btu/d) coal-gasification plant to produce SNG, regardless of the process selected, will
require a capital outlay of well over $1 billion. This amount approaches the total worth
of the Nation's largest utilities. Thus, one such coal-gasification plant could roughly
double the net worth of a large gas utility, while adding only a small amount (~ 10-15%)
to the utility's gas supply.
Because of the high capital requirements, coal-gasification plants are difficult to
finance and non-technical problems, primarily financial and regulatory uncertainties, are
generally the principal obstacles to coal-gasification processes. At present prices of
alternative energy sources, technical breakthroughs are needed to make the financial,
economic, and regulatory aspects of the coal-gasification technologies more attractive.
The Lurgi process is commercially available for coal gasification to produce high-Btu
gas, and all of the commercial plants currently proposed for SNG production in the
United States will be using this technology. Thus, the Lurgi process serves as the baseline
for measuring the economic potentials of technical improvements in coal gasification.
Table 1 shows the cost breakdown of a commercial Lurgi plant using noncaking
Table 1. Cost breakdown for a Lurgi gasification plant using non-
caking Western coals. Source: Private communication between
Western Coal Gasification Company (WESCO) and V. Bendanillo,
GRI.
Process Percentage of total plant investment
Gas purification and upgrading
shift conversion 2.5
gas cooling 3.0
acid-gas removal 15.6
methanation 6.2
total 27.3
Steam and oxygen plants
steam plant 16.6
oxygen plant 10.0
total 26.6
Gasi ficat ion 14.8
Effluent treatment and by-product
recovery
effluent water treatment 1.7
phenol recovery 3.2
tar or oil recovery 2.6
sulfur recovery 3. 3
total 10.8
General facilities and utility
systems
general facilities 4.3
utility systems 3.5
total 7.8
Miscellaneous
coal handling 1.0
ash handling 3.5
water treatment 2.7
SNG compression 1.0
water and SNG pipelines 4.5
TOTAL 100.0
4 S. S. PHNNHR et ai
Western coals as reported by WESCO. Reference to Table 1 leads to the following
conclusions: (a) The gasification section accounts for only about 15% of the total invest-
ment; however, its construction impacts heavily on what processes or operations are
needed before and after the gasifier. (b) Gas purification and upgrading represent a
high-cost area (27.3%) for high-Btu gas plants. For coal-gasification plants for electric
power generation, only gas purification is required, (c) The costs of steam and oxygen
plants (26.6%) exceed those of the gasification section.
Research directed toward improving high-cost areas through process simplification
and the use of improved materials, equipment, and instrumentation should reduce costs
and increase plant operability and reliability.
2.2.2 Low-Btu gas for electric power systems. Clean gaseous fuel can be produced and
used in electric power systems by either (a) combined-cycle turbogenerators, (b) fuel-cell
systems, or (c) direct firing of the fuel gas in boilers.
In any of these cases, electric-generating equipment is not simply added to a coal-
gasification plant. Coal-gasification plants must be highly integrated with the power
equipment in order to be cost-competitive with other electricity-generating systems. An
operating, combined-cycle generating plant based on coal has not yet been built and
operated in the United States. The Steag Lünen plant has operated in West Germany at
a scale of 170 M We. It uses Lurgi coal gasification to produce fuel gas, which is com-
busted in a pressurized boiler. The pressurized flue gas is then used to generate electricity
in a power-recovery turbine. In the Lünen experience: (a) environmental requirements
are not comparable to those in the United States; (b) the configuration of the plant yields
relatively low overall system efficiency; (c) the cycle is not representative of equipment
offered in the United States; (d) improvements to increase efficiency and make the system
competitive with present electricity-generating systems using coal combustion and
flue-gas cleaning are improbable.
A. Gasifier characteristics for the power industry
The objective of advanced electric systems is the integrated operation of coal gasifiers
with combined-cycle electric systems. Utility experience with gas-turbine, combined-cycle
systems, which use oil or gas, corresponds to about 10,000 MWe of planned and installed
capacity. To take advantage of this background, coal gasifiers should meet desirable
criteria (see Table 2 of Ref. 1). No single gasifier technology can satisfy all of these
criteria; however, a number of the second-generation coal gasifiers (now operating at
scales in excess of 100tons/d) incorporate satisfactory compromises that should be
applied to electric power generation. Coal-gasification plants for electric power must
emphasize factors relating to the economic competitiveness of presently available high-
capacity generating systems that produce power in a cost-effective manner and meet
today's environmental standards.
B. Incentives for combined-cycle generation
In Table 2, we summarize and compare the estimated performance characteristics of
coal-gasification and pulverized-coal powerplants. Powerplants using coal gasification
are seen to be competitive; they provide for better resource utilization of coal and water
and they markedly reduce emissions. The potential for improvements is large and
involves advanced, high-reliability gas turbines, as well as advances in engineering and
improved cycle configurations; the influence of the gasification process on the potential
for further improvement is small.
Of high priority for the power industry is integration of component units from
separate technologies into an optimal system to assure that coal gasification is used to
generate electricity in a reliable and economically competitive manner.
2.2.3 Medium-Btu gas (275-425 Btu/SCF) as an industrial fuel and petrochemical feed-
stock. Gasification of coal to produce a mixture of hydrogen (H ), carbon monoxide
2
(CO), and methane (CH ), termed medium- (or intermediate-) Btu gas, is a particularly
4
Coal gasification and coal liquefaction 5
Table 2. Comparison of coal-gasification and pulverized-coal power plants (plant capacity = 1000 MWe); costs are given
in mid-1976 dollars. Source: The Electric Power Research Institute, Palo Alto, California.
TEXACO BGC SLAGGER TEXACO PULVERIZED COAL
Cycles or processes for which conventional conventional advanced conventional
the system is usable combined-cycle combined-cycle combined-cycle steam plant
heat rate, Btu/kWh 8,820 8,410 7,300 9,934
coal use, tons/d 8,616 8,234 7,155 9,743
limestone use, tons/d -Ο- -Ο- -Ο- 1,800
sulfur oxides produced,
£b/MMBtu Ο.8 Ο.8 Ο.8 1.2
make-up water needed,
GPM/1,000 MW 8,000 6,420 1,400 13,000
total capital cost, $/kW 770-940 670-820 600-850 800-930
estimated operating costs,
mills/kWh 36-41 32-36 29-36 40-44
economical and environmentally sound route to coal-derived energy supplies. In addition
to meeting most industrial fuel specifications, medium-Btu gas is also a potential gaseous
feedstock for the petrochemical industry.
Evaluations of medium-Btu gas production show that such gas can be produced with
a higher thermal efficiency (i.e. a higher fuel-energy content of the gas relative to that of
the coal) than syngas (SNG) (65-75% compared with 60-70%), generally at lower cost per
unit of fuel energy. Low-Btu gas shows similar thermal and economic advantages over
SNG but has more limited use as fuel and feedstock because of the large amounts of
nitrogen diluent present.
Unlike low-Btu gas, medium-Btu gas is generally considered to be economically
transportable to industrial users and smaller utility generating stations within 100-150
miles of a centralized gasification plant. Thus, the economy of large-scale plants is passed
through to smaller end users. However, these advantages must be balanced against the
high cost of constructing separate distribution networks.
Medium-Btu gas is an excellent fuel for boilers and process heaters, equaling the
benefits of oil or natural gas. It can be used in utility plants as a substitute for oil or
natural gas. Its availability may permit continued industrial expansion, using boilers
designed for gas that are available at a fraction of the cost of coal-fired units with
scrubbers. Such a fuel gas is useful in process heaters. The investments for adapting
existing oil- or gas-fired facilities so that they can burn medium-Btu gas are modest
compared with retrofitting for direct coal or low-Btu gas combustion.
A mixture of CH , H , and CO meets a variety of industrial and utility needs.
4 2
Hydrogen and CO feedstocks may be produced for the following purposes: manufacture
of ammonia and methanol, hydrotreating and desulfurization of refinery streams, and
reduction of ores to basic metals. The H -CO mixtures may be used by electric utilities
2
as fuels in new, combined-cycle turbines and as feed in fuel cells for peaking and load-
distribution purposes; many existing oil- and gas-fired facilities could be retrofitted with
relatively minor modifications.
Essentially all pollutants can be removed from medium-Btu gas at a large centralized
plant. This procedure not only reduces the total environmental impact of the industrial
use of coal, but also allows dispersal of emission sources because the gasification plant
may be located in remote areas.
6 S. S. PENNER et al.
Medium-Btu gasification is a basic building block and more attractive for direct use
for a number of industrial and utility needs than most alternatives, but it is not currently
economically competitive with oil and natural gas. Technological developments and
demonstrations have not yet sufficiently reduced the high costs or economic and re-
liability risks to produce private-sector commercialization.
2.3 The principal coal-gasification systems and process-research recommendations
The general principles involved in coal gasification are illustrated in Fig. 1.
Three principal types of coal-gasification systems are discussed in this section: fixed-
bed (gravitating-bed) gasifiers, fluidized-bed gasifiers, and entrained-flow gasifiers.
2.3.1 Fixed-hed gasification. During the 1930s and 1940s, some 11,000 individual
gasifiers operated in the United States. Almost without exception, these were fixed-bed
reactors. The first high-pressure reactors were simultaneously introduced into commer-
cial practice in Germany by Lurgi. After the war, gasification of coal in the United States
was discontinued, but the operating range of fixed-bed (gasification) systems was further
extended by vigorous increase in the use of these reactors in the steel industry.
Most of the older fixed-bed reactors were 6-8 ft in diameter and consumed 20-80 tons
of coal per day. The use of high pressures raised this to 350-1000 tons per day. Modern
blast furnaces consume more than 5000 tons of coke per day at slightly elevated pressure.
Compared to fixed-bed systems, the impact of other gas/solid systems (reactor types) has
been minor.
The great advantages of the fixed-bed systems are extensive practical experience and
inherent efficiency, because they are effectively countercurrent heat exchangers. The solid
gasification fuel is preheated to the maximum temperature by heat recovery from the
gaseous products, which generally leave at temperatures between 150° and 425°C. At
higher pressure, the system also allows utilization of the heat released in the lower
temperature zone by exothermic reactions of tar and char with hydrogen to form meth-
ane. Finally, countercurrency also ensures complete consumption of the coal substance
and removal of ash, with only minimal unused carbon.
These advantages are offset by important drawbacks, all of which relate to the high
demand the fixed-bed gasifier places on the feed in terms of size consistency and free bulk
flow through the reactor (freedom from sticking or hanging). Finally, these reactors favor
the use of coals with high reactivity and high ash-fusion temperatures (these requirements
must also be met in fluid-bed units).
(H2)/(CO)>3 mectahtaanlyattiico n product gas (ΟΗψ etc.)
3H2 + CO ^
CO^HgS (H2)/(C0)>3
organic sulfur purification
compounds
catsahliyfttic .
CO^HpS
CcoH;4, c aHp.,, H2O cCoOnv +er sHio2On H purification orgcaonmicp osuunldfus r
C0 + H
2 2
feed coal I IOO-I 500°F
or lignite col_aj ,!,70ι 0°F + CH •HL:+C.A4r2K O: devolatilization reaction
C+f2HJ^= * CH^,AH<0 hydrogasification or methanation reaction
C + ri^D ΟΟ^Η^,ΔΗΧ)· steam-carbon reaction
+1
CO + H?0==^C02 H2i,AH<0: water-gas shift reaction
TT
steam heat
Fig. 1. General process scheme for producing methane from coal; endothermic reactions corre-
spond to AH > 0 and exothermic reactions to AH < 0.