coal liquification

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Coal Liquefaction

There are several avenues which can be employed to produce liquids from

coal. Figure 8-1 summarizes the various paths of converting coal to liquid fuels,

which generally are classified as either indirect or direct liquefaction. Indirect

liquefaction, which is already commercialized, involves gasification of the coal

followed by chemical processing at high pressure to yield a variety of liquid hy

drocarbons. One advantage of indirect liquefaction is that it yields a product mix

with a high percentage of liquid transportation fuel (e.g., gasoline), thus satisfy

ing one of America s primary energy needs.

The second approach is direct liquefaction, where the coal is hydrogenated un

der high pressures to form a liquid plus a solid residue. While this latter approach

has the attractive features of higher thermal efficiency and potentially lower pro

cessing costs than for indirect liquefaction, significant research and development

problems remain to be solved. Commercialization of these processes will proba

bly not occur until after 1990. Direct liquefaction also does not yield a high

percentage of gasoline but rather produces heavier components which do not

match up well with current fuel demands.

Given the choice between liquid and gaseous synfuel products from coal, coal

liquids have several distinct advantages over synthetic natural gas:

I. Liquefaction requires less chemical transformation and hydrogenation than

high Btu gasification. Since the HIC ratio of coal is 0.8, less hydrogen is

required to form a liquid

H C

2) than methane

H C

4). This should



oal Liquefaction 95

Indirect liquefaction of coal generally follows one of three process schemes:

1. Fischer- Tropsch

2. Methanol synthesis

3. Catalytic conversion of methanol to gasoline

Normally Schemes 2 and 3 are integrated in the same plant in order to maximize

production of gasoline. Using Fischer- Tropsch synthesis, it is possible to obtain

high yields of both low and high molecular weight products, but the selectivity

towards intermediate weight products such as gasoline or diesel fuel is not good.

In order to maximize gasoline product and minimize heavy ends production,

methanol is first produced, followed by Scheme 3 using the Mobil M process.

Fischer Tropsch Processing

In 1925, the German chemist team of Franz Fischer and Hans Tropsch devel

oped a catalytic process to produce a variety of fuels from reacting carbon mon

oxide with hydrogen. This technology was used in several German plants during

World War II for the manufacture of gasoline and other products. After World

War II, a pilot plant was operated by the U.S. Bureau of Mines in Missouri, and

a commercial plant (7,000 bbllday) was operated during the 1950s in Browns

ville, Texas. This latter plant suffered a number of operational difficulties and

was shut down when cheap sources of natural gas and oil became available.

In 1980 the only major coal liquefaction plant operating on a commercial scale

in the world was the Sasol (Afrikaans acronym for South African Coal, Oil, and

Gas Corporation) I plant in Sasolburg, South Africa, which uses Fischer-Tropsch



9

Coal Processing and Pollution Control

8-2

8-3)

can occur. 3,4

addition the above products can undergo secondary isomerization

and/or cyclization to form branched-chain and aromatic compounds. The selec

tivity and product mix of a given process is determined by the reactor configura

tion, catalyst composition, H2/CO feed ratio, and operating conditions tempera

ture and pressure). The types of catalysts employed commercially include iron,

cobalt, nickel, ruthenium, and zinc, and often contain promoters such as potas- ~-/

sium oxide) in small percentages.

For instance, if the fixed-bed Arge) process is operated with an alkali-rich

iron-based catalyst, a low H2/CO feed gas, and a low temperature, the wax selec

tivity can be increased from the normal 50 to above 75 . On the other hand,

operating the fluidized bed Kellogg Synthol) with an iron catalyst of low alkali

content and hydrogen-rich feed gas increases the methane selectivity from 10

to about 80 . Table 8-1 gives the typical product distribution for fixed- and

fluid-bed reactors. A wide product distribution is an inherent feature of the Fis

cher-Tropsch process. The maximum yields of gasoline and diesel fuel which

can be obtained in normal Fischer-Tropsch operation are about 40 and 18 ,

respectively. The normal H2/CO ratio is about 2: 1, with a temperature range of

450°F to 700°F and pressures from 5 to 40 atm.

South Africa the liquefaction process is usually operated to give maximum

gasoline selectivity. To meet octane specifications the required amount of gaso

line is hydrorefined to saturate olefins and remove all traces of oxygen-contain

ing compounds, followed by catalytic reforming. Hydrogenation is carried out

because straight-chain hydrocarbons produced by primary synthesis make a poor

quality gasoline. contrast, a good quality diesel fuel requires mainly straight

chain paraffins. Sasol II is designed to produce a mix of products: methane, light



Coal Liquefaction 97

Table 8

Product Distribution in Sasol 13,4

Product

Methane

CI

Light gas C,-C.

Gasoline

Cs-C12

Light distillate

CIJ-CI9

Soft wax

C,o-C30

Hard wax

C30

Oxygenates

Methanol Synthesis

Fixed Bed

RG

5

13

15

23

18

4

Fluid Bed

SYNTHOL

10

33

39

5

4

2

7

Methanol has the potential to be used directly as a transportation fuel, I but it

can also be converted to gasoline. The selective synthesis of methanol from CO

and H2 involves the following reaction:

8-4

Carbon monoxide and hydrogen may react in many other ways, but elimination

of the side reactions is accomplished by using very selective catalysts and appro

priate operating conditions. By minimizing the undesirable reactions, the synthe

sis reaction will proceed until equilibrium is reached. The equilibrium methanol

content in the effluent mixture decreases with increasing temperature and in

creases with the square of the pressure. Two generic methanol synthesis pro

cesses, called low and high pressure, are used commercially. 5.6 The low pressure

process operates at a lower temperature than the high pressure process, using a

different catalyst. Its advantage is that lower compressor costs are achieved.

The synthesis gas prepared for methanol production from coal gasification can



9 Coal Processing and Pollution Control

The use of carbon dioxide in the synthesis requires 50 more hydrogen than car

bon monoxide, thereby increasing the cost of gas compression. This disadvan

tage is compensated somewhat by elimination of the need to remove carbon diox

ide from the synthesis gas.

Preparation of the makeup gas synthesis gas) is the same for both the high and

low pressure processes, except sulfur removal is more rigorous in the low pres

sure case.7 The synthesis makeup gas might have the following composition:

Component

Hydrogen

Carbon Monoxide

Carbon Dioxide

Methane

Argon

Volume dry)

63.0

26.0

7.0

3.8

0.2

The hydrogen to carbon monoxide ratio from the gasifier is adjusted in a shift

reactor to achieve the above composition. Note that the ratio of 2: I for H2/CO is

not strictly required; generally a ratio between 2.3 to 2.5 is employed.

The high pressure process operates at about 5,000 psig. In large plants it is

economical to do all compression with centrifugal compressors. The minimum

capacity for such a plant is about 700 tons per day.6.7 The makeup gas is mixed

with the recycle stream in the last stage of the compressor and then proceeds to

the converter. Large plants typically use gas-quenched catalyst beds in the con

verter for temperature control. The converter outlet stream contains about 5

methanol by volume; the yield, based on CO

CO2 conversion, is approximately

95 -96 .

In the low pressure process developed by ICI see Figure 8-2), the makeup gas

is compressed to about 765 psig. It is then mixed with the recycle gas from the

synthesis loop and fed to the converter. The converter is similar to that used in




NAPHTHA, SYNTHESIS GAS, ETC.

F EEOSTOCIC

(NAPHTHA OR

HYQROCARBON

GAS-C02)

CRUOE

ETHANOL

TAN

IMP\mITJ[S

HIGH-SOIL ING IMPURIT IES

Figure 8-2. The ICI low pressure methanol synthesis process.

extraction column. Thermal efficiencies for either methanol process are in the

50 to 55 range.

Gasoline Synthesis

Currently, there is only one commercially available process for the synthesis

of gasoline from methano1.4,s This is Mobil s MTG process. Methanol is con

verted via a reversible dehydration to form dimethyl ether and then olefins:



oal rocessing and ollution ontrol

the temperature rise in the converter to a manageable level. About 80 of the

total heat of reaction is released in the conversion reactor. The reactor effluent is

condensed and the aqueous, liquid hydrocarbon, and gaseous phases are sepa

rated. Most of the gas is recycled. The converter may typically operate for 20

days before coking of the catalyst necessitates regeneration.

Table 8-2 gives material balance data for the Mobil M fixed-bed) process.

Pilot plant tests at the 4 barrel per day level have shown methanol conversion to

be very nearly stoichiometric, with 56 water and 43.5 hydrocarbons being

formed. About 75 of the hydrocarbons are in the gasoline fraction. In formulat

ing a gasoline of proper volatility, some of the n-butane formed is made part of ::-~

the gasoline. In addition, the remaining

C3

and

C4

gases, olefins, and isobutane

are alkylated to high-octane gasoline.8 Including the alkylation step raises the

yield of gasoline to nearly 90 . The following are typical properties of the syn

thetic gasoline:

Molecular Weight

Specific Gravity

Research Octane Number

irect iquefaction

93

0.720

96.8

Direct liquefaction requires addition of hydrogen to coal so that the

H

ratio

is increased to the range where the product is a liquid. Liquids produced are of

two principal types:

I. A synthetic, largely aromatic, crude suitable for further processing to gaso

line and other products.



Coal Liquefaction 2 1

Table 8 2

Product Distribution for Mobil MTG Process

Operating Conditions:

Converter Outlet Temp.

Pressure

Recycle Ratio

Space Velocity

Product Distribution:

Yields: wt of Methanol Charged

Methanol Ether

Hydrocarbons

Water

CO,

CO2

Coke Others

Total

Hydrocarbon Distribution

Light Gas

Propane

Propylene

I-Butane

N-Butane

Butenes

Cs Gasoline

Total

Gasoline

ncluding Alkylate)

LPG

Fuel Gas

Total

Source: Mobil Oil Corporation

780°F

315 psig

9:1

2.0

0.0

43.4

56.0

0.4

0.2

100.0

1.4

5.5

0.2

8.6

3.3

l.l

79.9

100.0

85.0

13.6

1.4

100.0




Figure 8 3 Methanol-to-gasoline route.

The design of a coal liquefaction process has the objective of generating a

product which has a composition as close as possible to existing liquid fuels.

This implies that the hydrogen to carbon ratio must be increased by adding hy

drogen ; other design objectives include removal of sulfur and nitrogen com

pounds and mineral matter. Liquefaction is accompanied by evolution of gaseous

hydrocarbons, water vapor, ammonia, and hydrogen sulfide not all nitrogen and

sulfur is released from the coal, however .

The liquefaction process is intimately related to low temperature pyrolysis4 in

the range between 350°C and 550°C.

In

fact, for most liquefaction processes,

pyrolysis is the rate-determining step. Pyrolysis reactions include loss of hy

droxyl groups, dehydrogenation of some aromatics, cleavage of methylene

bridges, and rupture of alicyclic rings, all leading to generation of free radical




ture carbonization, pyrolysis, solvent extraction, hydrogenation) affects the

product yields for the same coal.

15

The large variation in light and residual oil

yields is noteworthy.

Most coals when contacted with organic solvents imbibe fluid, swell, and dis

solve to some extent in the solvent. A solvent such as pyridine can dissolve a

large percentage of coal at low temperature, and its behavior is non-selective,

i.e., the residue resembles the dissolved material. The dissolved coal may be a

true solution or a colloidal suspension.

At temperatures above 350°C, a solvent such as anthracene oil can be em

ployed to dissolve the coal. This solvent promotes thermal depolymerization re

actions and increases liquid yields. A hydrogen atmosphere high pressure) can

further increase th~ yields and quality of the extract by stabilizing the free radi

cal reactions, thus reducing the molecular weight of the product. These hydro

genation reactions are catalyzed by the mineral matter of the coal as well as by

Table 8-3

Composition of Coal Liquids

Hydrocarbons

N-paraffins

Isoparaffins

Cycloparaffins

Benzene

Naphthalene

Tetralin

Anthracene

Phenanthrene

Acenaphthylene

Pyrene

Chrysene

Fluorene

Oxygen Compounds

Phenol

Indanol

Dibenzofuran

Benzonaphthofuran

Sulfur Compounds

Thiophene

Benzothiophene

Dibenzothiophene

Nitrogen Compounds

Indole

Quinoline

Carbazole

Acridine

Benzacridine

Dibenzacridine



4 oal rocessing and ollution ontrol

added external catalysts. Hydrogenation of the free radicals can also be enhanced

by using a hydrogen donor solvent such as tetralin. A hydrogen donor solvent

reacts with molecular gas-phase hydrogen and then transfers the hydrogen to

coal. The lower molecular weight liquefaction products then are more easily dis

solved in the solvent. Tetralin as well as some other solvents provide hydrogen

molecules which are more mobile than hydrogen gas alone, thus allowing lower

operating pressures. In these solvents the extraction efficiency can approach

100 under laboratory conditions.

The products from liquefaction are difficult to characterize chemically. Other

means of characterizing these liquids must therefore be employed, inCiudingl3.14

_J

1. Elemental analysis

2. Density, API gravity, viscosity

3. Distillation properties

4. Distribution of acidic, basic, and neutral compounds

5. Aromatic, paraffinic, olefinic carbons

6. Solubility in various solvents pentane, benzene, pyridine)

irect iquefaction Processes

Liquefaction process research and development has been particularly active in

the United States during the past decade; 17-19here are presently no commercial

processes of this type. Table 8-5 lists the current development programs which

are being tested on a pilot scale 5 to 1,000 tons per day).IO These processes have

all shown enough promise to pass beyond the small bench scale to the pilot stage.

They may be grouped under the following headings:



Coal Liquefaction

5

f Direct Coal Liquefaction Projects

Type

Process

eveloper

ocation

izeRC-I

Southern Company

ilsonville,

tons/day

ServicesL

ittsburg

Ft. Lewis

0 tons/day

Tacoma), WA

Oil)

H-Coal

ydrocarbon Catlettsburg,

50-600

Research, Inc.

tons/day

.S. Bureau of

ruceton, PA

.25 to 10

O

tons/day

SFonsolidation

Cresap, W VA

0 tons/day Coal Company now moth-

balled)

aytown, TX

50 tons/day

mothballed)

Note: See Chapter 6 for a discussion of pilot plants based on hydropyrolysis processes Toscoal,

Coalcon, CS/R).

Table 8 6

Comparison of Major Coal Liquefaction Processes1

SRC I

RC IIDS Coal

Pressure, psia

1,500,950,000,200

850

505050 40

0

400-70

76

00*4 95

5

704

2.4

.74.3.8-5.3

Recycle ofecycle ofecycle of

ecycle of

eactor

hydrogen-

eavylurry

ted solventistillate

Upflowpflowpflow, plug-

bullated-olumnlow tubular

ed cataly-

eactoreactor

ic reactor

Mineral

i-Mo for

o-Mo or

olvent

i-Mo

a-

tion



Coal Liquefaction 7

organic sulfur. In most cases the residue will not satisfy a 70 sulfur removal

requirement. The overhead from the vacuum flash, the wash solvent, and light

liquids removed in other parts of the process are separated into I) a light C5 to

400°F liquid by-product, 2) a 400°F to 500°F boiling liquid, used as filter wash

solvent, and 3) a 500°F to 800°F boiling process solvent, which is recycled. Ta

ble 8-7 presents the typical product distribution for the SRC-I process. SRC-I

tests at Ft. Lewis and Wilsonville have indicated that the process is operationally

reliable except for mechanical problems with valves and solid/liquid filtration.

Some valves do not survive beyond one month of operation. Promising ap-

Table 8·7

Product Distribution for Solvent Refined Coal SRC-1 10

Typical SRC Composition:

C

H

N

o

S

Ash

HHV

Operating Conditions:

Temperature

Pressure

Coal Feed Rate

Solvent/Coal Ratio

Gas Feed Rate

Hz Cone. in Feed Gas

Typical Yields:

CI

87.7

5.3

1.2

5.0

<0.5

0.2

16,000 Btullb

800-900°F

1,000-2,500 psig

25-100 Ibthrtft3

1.5-3.0 weight basis)

15,000-30,000 scf/ton-coal

60-95 mol

Yield wt dry coal)

2.2




proaches to replace leaf filters include continuous centrifugation and the Kerr

McGee critical solvent deashing process.

20

Another version of this process, called SRC-II, produces an all-distillate liquid

product at the expense of higher hydrogen consumption. This is done by increas-

ing the residence time and using a recycle slurry of catalytically active minerals,

such as iron sulfide pyrite), yielding 15 -20 gas CI-C4), 45 -50 distil-

late syncrude including 15 naphtha), and 35 -40 residue 5 -10 undis

solved coal, the rest SRC). The distillate yield is about 2.5 bbllton coal with a

hydrogen requirement of 5 of the coal weight.

20.21

The sulfur level of the SRC

usually satisfies the 70 removal standard. The SRC-II process eliminates the ,

solid/liquid separation step. Not all coals are suitable for SRC production, with

coal mineral matter believed to be one reason for high variability in process per

formance.

Consol Synthetic Fuels CSF . This process is an early example of the first

class of liquefaction processes, involving a combination of pyrolysis and hydro

genation. Hydrogen is usually supplied through a hydrogen donor solvent such as

tetralin, although sometimes a small amount of molecular hydrogen is added.

Ash is filtered or otherwise separated and the partially hydrogenated coal further

hydrogenated. The CSF process, shown in Figure 8-5, used a ZnCh catalyst at

4,200 psi and 465°C for this stage. The hydrogenated solvent was recovered for

recycle. The CSF process was operated previously at the 20-ton-per-day level,

HYDROCARBONS

HYDROCARBON

GASES TO REFINERY



Coal Liquefaction 9

HYDROGEN GAS

COAL

HEAVY SYN.CRUDE

SYN. CRUDE

SLURRYING

95 C

EXTRACTION

380 C

SLURRY

SOLVENT

RECOVERY

LI G HT

Oil

Ii

SOLVENT

EXTRACT

HYDROGENATION

4200

psj

65 C

HYDROGEN

DISTillATION

GAS

RECYCLE SOLVENT

lOW

TEMPERATURE

CARBONIZATION

CHAR

HYDROGEN - DONOR SOLVENT

Figure 8-6. CSF process-synthetic crude from coal.

but has now been abandoned as a commercial candidate due to operational prob

lems, mainly in solid-liquid separation at high temperature and pressure.

I?

Exxon Donor Solvent EDS . This process is similar to the CSF process and

is now the leading commercial donor solvent candidate. The EDS process is de

signed to maximize liquid products. It has been operated at a pilot scale 1.0 ton

per day), and demonstration scale 250 tons per day) in Baytown, Texas. The

feed coal is crushed, dried, and slurried with hydrogenated recycle solvent see

Figure 8-6, References 10 and 22). This slurry is fed to the non-catalytic lique




Table 8 8

Product Yields of EDS Process for Different Coals 10

Residence time, min

Yields, wt maf coal:

H2

H20

CO,

H2S NH3

C,-C3

gas

C.-IOOO°F liquid

IOOO°F bottoms

Illinois

bituminous

40

-4.3*

12.2

4.2

7.3

38.8

41.8

Wyoming

subbituminous

6

-4.6

22.3

0.9

9.3

33.3

38.8

Texas

lignite

25 4

-3.9

21.7

1.7

9.1

33.3

38.1

Negative values denote consumption

essentially all of the organic matter in the bottoms to liquid products and fuel

gas. Hydrogen for the process is produced by steam reforming of the light hydro

carbon gases. Alternatively, partial oxidation gasification or direct combustion

of the vacuum bottoms may be employed. In the current version of EDS, the

latter approaches are preferred over Flexicoking.

The total liquid product is a mixture of the liquefaction and Flexicoking prod

uct streams. That portion of the liquids which boils below 350°F is suitable for

gasoline and petrochemical manufacturing, while the higher boiling components

may be used in fuel oil applications. The higher boiling fraction contains about

0.6 wt) sulfur and 0.8 wt) nitrogen. These levels maybe reduced by further

hydrotreating.

The testing of the EDS process has been sponsored by Exxon plus other pri

vate and public organizations. The coals tested up to 1982 included Illinois No.6



Coal Liquefaction

211

HYDROGEN RECYCLE

H20

FUEL GAS

Figure 8 7

Exxon donor solvent EDS process.

bed of ebullated catalyst. The cobalt-molybdate catalyst is fluidized by the liquid

feed. Depending on the operating conditions, the product yield can be all distil

late material or distillate plus a liquefied residual.

The gaseous output from the reactor is scrubbed with a medium volatility oil to

remove light hydrocarbons, and the resulting stream of hydrogen is recycled.

The liquid slurry leaves the top of the reactor and is flashed to atmospheric pres

sure. The vapor phase from the flash is a high-Btu gas after purification to re

move

H2S

and CO2• The liquid phase consists of syncrude, ash, and unreacted




Table 8 9

Product Yields of H Coal Process10

Recycle oil/coal ratio

Reactor temperature, of

Hydrogen partial pressure, psia

Yields, wt of dry coal:

C,-C3

C4-400°F

400-975°F

975°F

Unconverted coal

Ash

H

NH

H2S

CO

COz

Total

Hz consumption, wt of dry coal

Sulfur in 400°F

oil, wt

Fuel oil mode

2.1

850

1,760

7.71

16.90

18.28

32.45

6.75

10.95

6.67

0.53

2.55

l.01

103.80

3.80

0.49

Syncrude mode

2.1

850

1,830

9.97

23.66

23.21

19.25

5.68

11.67

7.37

0.84

2.65

0.95

105.25

5.25

0.26

boiler fuel. The major problems experienced in these tests were largely mechani

cal e.g., valve and pump failures);25,26 in addition, various components in coal

can contribute to catalyst poisoning.

A similar process Synthoil) was tested by the Bureau of Mines in the

1970s.4,I0,17Coal high sulfur bituminous) forms a 30 slurry in coal-derived oil

and passes through a fixed bed of pelletized cobalt-molybdate catalysts under

conditions of turbulent flow. Pressures and temperatures are the same as for H

Coal. Turbulence promotes contacting and prevents obstruction, resulting in a

low sulfur and ash product. This process is no longer a candidate for commercial




300 to 500. The solid residue is similar to char, although with a higher volatile

content than with most chars obtained from pyrolysis.4

roperties of

coal

liquids. Coal liquids produced from direct liquefaction are

not suitable for use as a high grade fuel without further processing. Coal liquids

generally resemble petroleum residual oils black oils more than other petroleum

products, although their physical and chemical characteristics are sufficiently

different to place them in a separate classification.28 The distillation curves of

several coal liquids and of a typical domestic crude oil are compared in Figure 8

8. In general terms coal liquids contain more nitrogen and oxygen than petro

leum crudes. 29 Coal liquids are more aromatic and correspondingly more hydro:

gen-deficient than equivalent cuts from crude oils, thus the carbonlhydrogen

ratios of most coal liquids are considerably higher than those for petroleum

100

COED SYNCRUDE

~

60

°

~

w

:1:

:

..J

0

40

I

I~;

I

UPGRADED

SRC

0

80

TEXAS CRUDE



214


crudes (see Table 8-10). Some coal liquids contain substantial quantities of as

phaltenes, a potential problem for subsequent upgrading. Coal liquids contain a

far higher proportion of higher boiling materials.

The upgrading of coal-derived liquids should achieve the following goals:

1. Reduction or removal of sulfur, nitrogen, oxygen, trace metals, ash.

2. Hydrogenation and increase of the hydrogen/carbon ratio.

3. Reduction in viscosity and boiling range.

4. Improvement of storage stability.

5. Reduction in toxicity and carcinogenicity.

(For data on upgrading of synthetic crudes, see References 28, 30, and 31.)

Commercialization and Economics of Synfuel Production

During the 1970s a great deal of interest in synthetic fuels arose in the United

States as well as the world because of the rapidly escalating price of oil and

shortfalls in oil supply. However, it appears that responses to the supply-demand

situation, such as increased conservation, production of more fuel-efficient auto

mobiles, additional oil production, and a flattening of oil prices, have considera

bly eased market pressures. It is doubtful that there will be much incentive (other

than for strategic purposes) during the 1980s to develop synthetic fuels, simply

because the cost of coal liquids is higher than that for crude oil. If oil prices

remain stable during this decade, the economic justification of a liquid synfuels

venture is very unlikely and may actually grow less attractive.

Even when the projected costs of synfuels appeared to be comparable to those

of conventional fuels in the late 1970s, there was still too much uncertainty in

market conditions to undertake a large-scale commercial venture with capital




1. The difficulty in raising large amounts of risk capital by developers.

2. The lack of financial incentives, including faster depreciation, higher debt

financing, and tax credits. 32

3. The uncertainty about future world oil prices as well as future monetary

inflation.

In the absence of a concerted government program to stimulate synfuels, the pri

vate sector is and will be very reluctant to undertake a major program in coal

liquefaction. _

Based on a variety of studies on costs of synthetic fuels from coal and oil

shale,33,34 it appears that oil from oil shale and medium Btu gas are the most

economically attractive options for the near future. Table 8-11 summarizes the

approximate capital and operating costs (1980 dollars) for a variety of synfuel

options for equivalent 50,000-barrel-per-day plants, while Table 8-12 gives the

cost of fuels using 100% equity financing and a 10% rate of return (no inflation

effects). ,33 The strategy which is most attractive appears to be combined produc

tion of liquid fuels with SNG, rather than production of methanol or gasoline

only. The costs stated here probably have

±

30% reliability, which makes syn

fuel production potentially much more expensive than gasoline from crude oil.

Table 8-13 gives the distribution of various products and energy efficiencies ex

pected from various synthetic fuel options. The fraction of transportation fuel

includes methanol, gasoline, and LPG. In general fuels produced from indirect

Table 8-11

Best Available Capital and Operating Cost Estimates for Synfuel Plants

Producing 50,000 I Oil Equivalent of Fuel to End Users1




Table 8-12

Consumer Cost of Various Synthetic Transportation Fuels

With 100 Equity Financing and 10 Real Return on

Investment Plant or Refining Gate

Plant or Refinery Gate

elivered Consumer Cost of Fuel

/Gallon Gasoline

/bbl 011 Equivalentquivalent

/106 Btu

Gasoline from32/bbl Crude Oil

47

.20.50 52.30

0.40

43.300.60 58.603.00

Gasoline/SNG

49

.250.00

Gasoline

67.602.90 52.300.40

77

.85

4.60

45.15.10

68

.854.70

71

.804.50

liquefaction tend to match up better with U.S. transportation fuel requirements

than those from direct liquefaction. While there are some practical problems in

using methanol or methanol gasoline in current automobiles, 35 there is long




It is clear that research and development funding required to bring a single

direct liquefaction process to commercialization is significant, on the order of

several billion dollars. Hence when only a few plants are to be constructed, it

will be difficult for the private sector to absorb this front-end capital require

ment. Another impediment facing direct liquefaction plants is the wide variety of

compounds, some of which are carcinogenic, that are produced during process

ing.48 On the other hand, indirect liquefaction plants also pose a range of occupa

tional hazards;1 processes based on the Lurgi gasifier will generate a large quan

tity of pyrolysis products. For this reason entrained-bed gasification such as

Texaco) may be preferred over the fixed-bed systems.

Table 8-13

Selected Synfuel Processes and Products and their Efficiencies

Energy Efficiency

)

Fuel Transportation Fuel

Product Product

(Coal Input) (Coal Input)

NA NA

Process

Oil Shale

MethanoliSynthetic

Natural Gas SNG)

Methanol

Mobil Methanol to

Gasoline/SNG

Fuel

Product

( of output)

Gasoline 19)

Jet Fuel 22)

Diesel Fuel 59)

Methanol 48)

SNG 49)

Other 3)

Methanol 100)

Gasoline 40)

SNG 52)

65

55

63

33

27

8 oal rocessing and ollution ontrol



eferen es

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S.

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Organic Chemistry of Coal

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oal iquefaction

9



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uids by Hydrotreatment, ACS Symposium Series 179, Washington, DC

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oal rocessing and ollution ontrol

38. C. E. Braun and Co., Coal to Methanol Via New Processes Under Devel

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coal liquification

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