United States     Industrial Environmental Research Laboratory EPA-600/8-80-002
Environmental     Research Triangle Park NC 27711      January, 1980
Protection Agency

Research and Development




SASOL: South  Africa's



Oil  from Coal Story --





Background for



Environmental Assessment

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                                      EPA-600/8-80-002
                                          JANUARY 1980
                     SASOL:
SOUTH AFRICA'S OIL FROM COAL STORY

            - BACKGROUND  FOR
      ENVIRONMENTAL ASSESSMENT
                         By


                      J. L. Anastai
                       TRW, Inc
                     One Space Park
               Radondo Beach, California 90278
                  Contract No. 68-02-2635
              EPA Project Officer: William J. Rhodes
            Industrial Environmental Research Laboratory
          Office of Environmental Engineering and Technology
               Research Triangle Park. N.C. 27711
                      Prepared for

              U. S. Environmental Protection Agency
               Office of Research and Development
                   Washington, D.C. 20460

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                                ABSTRACT

     The report describes the world's only oil-from-coal  plant,  known as
SASOL, operated by South Africa since 1955.  When almost  $7 billion  worth
of expansion is completed in the early 1980's, three SASOL plants will
produce a total of 112,000 barrels of oil per day, or about half of South
Africa's needs.  Production costs average $17 per barrel, well  below the
1979 OPEC price of more than $20 per barrel.

     South African motorists pay about $2.40/gallon ($0.63/liter) of gaso-
line at the pump.  SASOL converts coal to liquid fuels in two steps: (1)
the coal  is gasified with oxygen and steam under pressure to yield a mix-
ture of reactive gases, and (2) after being cleaned of impurities, the
mixture is passed over an iron-based catalyst in Fischer-Tropsch synthesis
units to produce liquid fuels.  SASOL's operation is helped by South Africa's
abundance of cheap labor and low cost coal.

     The U.S., like South Africa, has vast coal reserves.  Although com-
parisons are difficult, it has been estimated that oil could not be produced
from coal in the U.S. for less than $27 per barrel and perhaps as much as
$45.  The South African system is the only commercially proven process for
the production of synthetic liquid fuels.  The report provides some of the
background on a process that will receive high priority for environmental
assessment.
                                    ii

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                                 CONTENTS

                                                                     Page

Abstract	   ii
1.  Introduction  	    1
2.  Historical Background	    4
3.  Sasol I, Sasol II, Sasol III	    7
4.  Detailed Description of the Process 	   10
    4.1  Sasol I	   10
    4.2  Sasol II and Sasol  III	   25
5.  Conclusions   	   32
6.  References    	   34

List of Figures
1.  South Africa's Sasol Process	    2
2.  Block Diagram of Sasol I Process  	   11
3.  Fixed Bed Arge Reactor  	   21
4.  Fluid Bed Synthol Reactor	-	   23

List of Tables
1.  Typical Analysis of Sasol Coal	   12
2.  Typical Composition of Raw and Pure Synthesis Gas	   17
3.  Comparison of Fixed Bed and Fluid Bed Conditions and Products  .   19
4.  Sasol Products and  Intermediates	   26
                                   iii

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                            1.   Introduction

     Since 1955, South Africa  has  operated  the  only oll-from-coal  plant
1n the world.  The plant 1s known  as Sasol, an  acronym  for South African
Coal. 011, and Gas Corporation.  When almost  $7 billion of expansion  Is
completed 1n the early 1980's,  three Sasol  plants  will  produce a total of
112,000 barrels of oil a day or about half  of South Africa's  needs.   Pro-
duction costs amount to $17 per barrel,  well  below the  OPEC price  of  around
$20 per barrel and much less than  the $31  per barrel that South Africa has
to pay on the spot market.  South  African motorists pay about $2.40 per
gallon of gasoline (63^/11ter)  at  the pump.

     Sasol converts coal to liquid fuels In two steps (Figure 1).   First,
the coal 1s burned with oxygen and steam under  pressure to yield a gaseous
mixture which 1s principally hydrogen, carbon monoxide, and methane.   This
gas 1s cleaned of Impurities using processes  that produce valuable chemi-
cal by-products.  Once this Is completed,  the gas 1s passed over an Iron-
based catalyst 1n the second step to produce liquid fuels.  Sasol  produces
a full range of hydrocarbons Including fuel gas, liquefied  petroleum  gas
(LPG), gasoline, dlesel oil, parafln waxes, and chemicals such  as  alcohol
and acetone.  The yield of products obtained can be altered  by changing
such variables as the temperature, pressure, catalyst, or feed gas com-
position.

     Even though Sasol's operation 1s helped by South Africa's abundance
of cheap labor and low cost coal, Sasol's  success Indicates  that producing
synthetic fuels from  coal  1s one  solution  to meeting the energy needs of
a country without depending on natural  gas or  crude oil.

     The United States,  like South Africa, has vast coal  reserves  and
decreasing  reserves of natural gas and  crude oil.   The current world-wide
energy  crisis  has revealed  the vulnerability of the United States' oil
and  natural  gas  supplies to uncontrolled events 1n  other parts of the
world.  Therefore coal must by necessity play  an  ever widening role  1n
America's energy  future.   The abundance of oil  and  natural  gas In the
past has  determined the  energy forms  Americans are  accustomed to using.
                                     1

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      CONVERTING  COAL  INTO  SYNTHETIC  FUELS
                                            (Tars, particulates, sulfur compounds,
                                            and carbon dioxide removed)
350-550
pounds pressure
per square inch
(24OO-3800 kPa)
                                                            Gas
                                     Catalyst
                                     (iron oxide —rust)
         Steam   J
                      330-360
                      pounds pressure
                      per square inch
                      (2300-2BOO kPa)
         Oxygen
       (Allows controlled
       combustion for heat)
   (Supplies hydrogen from water)
Ash
        (Hydrogen,
        carbon monoxide,
        and methane)
Coal, steam and oxygen are
burned under pressure in the
gasif ier. yielding a gas com-
posed mostly of carbon mon-
oxide and hydrogen. That
gas is passed over a catalyst
to produce fuel gas and
liquid fuels.
                   Figure 1.  South  Africa's Sasol  Process

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Coal 1s a solid fuel.  If coal 1s to be more flexible for America's current
market requirements, 1t must be converted to the gas and liquid energy
forms that meet today's needs.  For this reason, the South African Sasol
process 1s of great Interest to Americans.

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                         2.  Historical  Background

     South Africa has large deposits of low grade coal  but  no  deposits of
oil have ever been found.  The country depends  on coal  for  about  80% of
Its energy needs, more than any other modern Industrial  nation.   The
possibility of producing hydrocarbons from coal has  always  attracted the
attention of Its scientists.  In 1927, a White  Paper was published
discussing the available processes for the production of 611 from coal.
Developments 1n Germany were closely followed,  especially after the first
announcements of the commercial feasibility of  the F1scher-Tropsch  process
for the conversion of coal  gas(to liquid hydrocarbons were  made 1n  1935.
Between 1936 and 1939, nine plants, with a total  rated annual  output of
820,000 tons (740,000 metric tons, mt) of synthetic  oil, were  erected  In
Germany.  The synthetic fuel Industry developed by the Germans during  the
war was highly uneconomical but 1t provided gasoline for tanks, trucks,
and planes.  Of their final products, 46% was gasoline, 23% dlesel  oil,
3% lubricating oil, and 28% was refined waxes,  detergents,  and synthetic
fat.  After the war, the relative costs of coal and oil dictated  the
shutdown of the German synthetic fuel Industry.  Germany has done little
1n the field since.

     The first large-scale German plant was still under construction  1n
1935 when a South African mining corporation, the Anglo Transvaal Con*
solldated Investment Company, better known as Anglo Vaal, acquired the
South African rights to the F1scher-Tropsch process.  Valuable pioneering
work was done by Anglo Vaal In the 1930's.  Preliminary tests were carried
out on coal found 1n the eastern Transvaal district of South Africa,  and
during 1937 a complete specification for a suitable plant was drawn up.
Tenders were Invited but progress on the project was Interrupted  by the
outbreak of World War II 1n 1939.

     United States  scientists and engineers had been frequent visitors to
Germany during the  1930's.  During  that time the United States was working
on Its own variation to  the F1scher-Tropsch process which used a moving
powdered catalyst rather than  the stationary pelletlzed catalyst developed

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by the Germans.  South African Interests  acquired  rights  to  the American
version of the Flscher-Tropsch process  toward  the  end  of  the war.

     In 1946 a new study was made and negotiations started with the  South
African government for an agreement on  the fiscal  structure  within which
an oll-from-coal  plant could be established.   In 1947, the Liquid Fuel
and 011 Act was passed and a Liquid Fuel  Advisory  Board was  established.
It was evident that the new Industry would be  one  of the  biggest single
enterprises ever established In South Africa and that Its success would
very much depend on such factors as government policies and  taxation.
The Advisory Board was Instructed to examine all factors  Involved and  to
draw up a license which would give this new Industry security  for at
least a number of years.  This license  was finalized 1n 1949.

     By that time. Orange Free State gold mining expansion was 1n  full
swing and capital for less spectacular  operations  was scarce.   At  this
stage, the sponsoring company approached the  government for  financial
assistance.  The great capital outlay required for the erection of a plant
was beyond the means of Anglo Vaal.  An Interim Commission appointed by
the government to examine the proposed  undertaking recommended that the
process should be taken over from Anglo Vaal  and that a government
financed company should proceed with the venture.

     The South African Coal, 011, and Gas Corporation Ltd. (Sasol)  was
formed and Incorporated under the Companies Act 1n September 1950 as an
ordinary public company.  It  Is not a government company 1n the normally
accepted sense, but all Its shares are held by the Industrial  Development
Corporation, a government company with Its own charter.  The government
appoints the majority of directors, Including the chairman,  and the re-
maining directors are appointed by the Industrial  Development Corporation.
Sasol operates like a normal  business concern, with an autonomous board
of directors and Is subject to South African company  law and taxation.

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     The new company Invited several  Internationally known engineering
firms to submit suitable proposals with estimated costs for a  complete
Installation.  After examining the five offers received It became clear
that Important technical and economic advantages would result 1f the
processes submitted by one German and one United States company were
combined Into an Integrated project.

     The Ideal site for the oll-from-coal plant proved to be the northern
corner of the Free State.  Here a vast coal  field exists close to the Vaal
River and the concentrated market of the country's Industrial  center of
the Wltwatersrand.  Sasol acquired 8000 acres (3000 hectare) of farmland for
the erection of Its factory complex and the establishment of the township
of Sasolburg.

     Shaft sinking at Sasol's coal mine and the planning of the plant and
the township commenced In 1951.  In 1955 reaction was accomplished for
the first time 1n the synthesis reactors.  By the end of the year the
first motorists filled up their tanks with Sasol gasoline.  Sasol's total
capital Investment was In the vicinity' of $450 million.

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                     3.  Sasol  I, Sasol  II,  Sasol  III

     The successful operation of the first Sasol  plant (hereafter referred
to as Sasol I) represented a major pioneering achievement In the area  of
coal technology.  Sasol I Is a vast complex  which Includes 1n addition to
Its o1l-from-coal plant, a refinery and  facilities for producing Important
Industrial petrochemical feedstocks.  The plant presently 1s the only  fully
Integrated commercial synthetic fuels from coal plant In the world.  Despite
many technical difficulties that had to be overcome during the aarly years
after startup, In most cases the actual  output now exceeds the design figure.
Sasol I converts five million tons (4.5  million mt) of coal per year to
160 million gallons (600 million liters) of gasoline plus vast quantities
of liquid and gaseous fuels and petrochemicals.  And contrary to early
predictions, Sasol I has turned Into a commercially profitable undertaking.
Pretax profits 1n 1978 were $140 million on  sales that totaled close to
$1 billion.  The oil produced by Sasol I Is  better quality than normal
crude oil because the sulfur and other Impurities have already been re-
moved before the refining step.  Gasoline from Sasol 1s Indistinguishable
In look and smell from gasoline refined from crude oil and no problems
have been experienced 1n using liquid fuels  from Sasol 1n blends for
regular and premium gasoline and dlesel  oil.  Gasoline from Sasol I
accounts for about 7% of the market 1n South Africa.

     The first step 1n the production of oil 1s the gasification of coal.
Lurgl pressure gaslflers using steam and oxygen were selected because their
operablUty had already been demonstrated and they had the advantage of
being able to work on the low grade, high ash coal available to Sasol.
The crude synthesis gas from the Lurgl gaslflers 1s fed to a gas purifica-
tion unit where  It 1s scrubbed with methanol to remove sulfur, carbon
dioxide, tars, oil, phenols, ammonia, cyanides, and other unwanted com-
ponents.  The purified  synthesis gas then undergoes the Flscher-Tropsch
synthesis process, the  combination of hydrogen and carbon monoxide with
the aid of an Iron catalyst to produce a range of hydrocarbons Including
motor fuels.

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     Two Flscher-Tropsch synthesis processes  are used  at  Sasol  I:   the
German  developed process In which the pelletlzed catalyst  1s  packed
Into a fixed bed reactor, and the American concept 1n  which the powdered
catalyst 1s swept along by the gas stream In  a  circulating  fluid bed  reactor
system.  The first process produces mainly higher boiling point materials
consisting of waxes, some oils with medium boiling point  such  as dlesel
oils, and smaller amounts of gasoline, liquefied petroleum  gas and  chemicals.
In contrast, the second process produces mainly low boiling point materials
such as liquefied petroleum gas and gasoline  as well as a considerable
amount of chemicals such as alcohol and acetone.  The  unique combination
of the two processes yields virtually the full  range of products normally
derived from crude oil In addition to a number  of others  usually manu-
factured 1n petrochemical plants.  Sasol I 1s also the major supplier of
Industrial gas via a high-pressure pipeline to  South Africa's  Industrial
areas.

     Sasol I has become the hub of South Africa's chemical  Industry,  a
group of about 30 plants producing a large range of petrochemical  products:
fertilizers, plastics, synthetic rubber, detergents, chemicals.  In order
to meet the ever growing demand for Its products, Sasol I has  successfully
Initiated and completed Improvement and expansion programs  over the years
to supply Important feedstocks (butadiene, styrene, ammonia, ethylene)  to
the chemical Industry.  In addition, 1n 1975  Sasol I Implemented a $65
million expansion program which Increased the capacity of the gasification
plant by 40% and which doubled the supply of Industrial gas.

     As a result of rising crude oil  prices  since the  Yom  Klppur War (1974)
and  the Arab oil boycott, the  South African  government 1n  a major move away
from dependence on  Imported crude oil announced  1n December 1974 that 1t
would  build a second  oil-from-coal  complex,  Sasol  II.  In  addition,  the
move will save considerable  sums  1n foreign  exchange which South Africa
uses to pay for Imported oil.  Sasol  II will  be  three times the design
capacity of Sasol I,  or  In terms of petroleum production, Sasol II will
be the equivalent of  a refinery capable of refining 2.9 million tons (2.6
million mt) per year  of  crude  oil.  The plant will consume 14 million  tons
(12.8 million mt} per year of  coal  as compared  with five million tons
(4.5 million mt) at Sasol  I.         .
                                    o

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     Sasol II 1s based on the same technology as  Sasol  I, that 1s, Lurgl
gaslflers followed by the Flscher-Tropsch  synthesis.  Sasol  I uses both
the fixed bed and circulating fluid bed synthesis processes  to produce the
full range of light to heavy hydrocarbons.  However,  the objective of
Sasol II 1s to produce motor fuels (gasoline and  dlesel) for which the
circulating fluid bed Is more suited.  In  addition, the possibilities for
scale up are limited for the fixed bed reactor.   For  these reasons,  the
Sasol II plant will use only circulating fluid  bed synthesis reactors
which were perfected at Sasol I.

     Construction got under way In 1976 on a flat, treeless  1850 acre
(750 hectare) site about 80 miles (130 km) east of Johannesburg. The work
force reached 15,000 during peak construction and the plant  1s  scheduled
for completion early In 1980.  In addition, a town called  Secunda (Latin
for second) Is being built nearby.  The Sasol  II  complex will  produce
enough gasoline to supply 30% of South Africa's motor fuel  needs.  Sasol
II will cost $2.8 billion and 1s being financed by Increased gasoline
levies, by suppliers' credits, and by government-voted money.   To put  the
cost In perspective, South Africa expected to spend $2.3 billion on
Imported oil 1n 1979.

     Immediately after the downfall of the Shah of Iran 1n early 1979,
South Africa announced the planned construction of Sasol III alongside
Sasol II.  The new Iranian revolutionary government had decided to  cut off
oil supplies to South Africa.  Iran had been South Africa's principal
supplier.  Sasol III will be almost an exact copy of Sasol  II  to save
design costs, and may be ready for full production by 1984.   Because of
Inflation, construction costs for Sasol III are estimated  at $3.8 billion.
Once the three plants are 1n operation, they will produce  about 112,000
barrels of oil per day, approximately half of South Africa's needs  1n  the
1980's.

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                  4.   Detailed  Description of the  Process

     The Sasol  I complex 1s  made up of the following processing units:
     •   Coal mining  and preparation
     •   Coal gasification
     •   Oxygen and steam production
     •   Gas purification
     •   Flscher-Tropsch synthesis
     •   Recovery and treatment of  gaseous products
     •   Reforming of methane to synthesis gas
     e   Recovery and refining  of liquid  products

     The Sasol  II and Sasol  III complexes with  some modifications  consist
of the same processing units.  The  units  that make up  a  Sasol  plant along
with the reasons for  their selection  are  described 1n  this  section.
Differences between the three Sasol plants will  be pointed  out.  A block
diagram of the Sasol  I process 1s shown 1n  Figure 2.
4.1  Sasol I
     Sasol I 1s located 50 miles (80 km)  south  of Johannesburg on  top of a
vast coal field close to the banks  of the Vaal  River which  1s  South Africa's
major source of water.  Sasol I Is  supplied  with coal  from  Its own nearby
mine, Sigma Colliery.  Production amounts to five million tons (4.5 million
mt) per year.   Sigma produces a non-caking,  low-grade  coal  with an ash
content of 30 to 35%, a sulfur content of 0.5%, and  a  heating value of
8380 Btu's per pound (19,480 kJ/kg) on a dry basis.  A typical analysis Is
shown 1n Table 1.  The coal  1s present 1n three seams, having mineable
heights of 8 to 10 feet (2.5 to 3m) each.   The seams  are separated by
layers of shale, mudstone, and sandstone of varying  thickness.  The mine
1s under 100 to 200 feet  (30 to 60 m) of white sandstone.

     The mining technique used 1s the mechanized room-and-pWar.   The
coal recovery efficiency  1s approximately 52%.   Mined  coal  1s transported
via conveyor to primary crushers situated at the bottom of the Inclined
coal hauling shafts.  The coal 1s lifted to the surface by conveyor and
discharged  Into storage bunkers of 12,000 ton (11,000 mt) total capacity.

                                     10

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AIR ^

OXYGEN
PLANT

COAL HIKE coAL_
AND *
PREPABATIDM
POWER
PLANT
OXYGEN _
STEAM
_J_
| COAL 1 ^ SASIFI
ASH 1

~ LUR
1 ,
\
GJ
COOI
\
x SULFUR .TrrTronD /V H2S PURIF1


\
1
FT7F.D BED
SYNTHESIS
ARPF
\
1

i
CATION!
GI 1
RAW
,GAS :
li<> -w
LING
*—
CATION!
•ISOL 1
(PURE
GAS
,
PRODUCT TAIL . METHANE
RECOVERY GAS
LIC
PROD
i
UID INDU!
UCTS fl
~ REFORMER
TAIL GAS
5TRIAL
^S

hi PHFNfKni VAN


JL TAR J
*|DISTILLATION|

FLUib otu
j»i SYNTHF^T*;
5YMTHr>l
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PRODUCT
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LIQUID
PRODUCTS
Figure 2.  Block Diagram of Sasol  I  Process
                     11

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          Table 1.   Typical Analysis of Sasol Coal
                                Sasol  I         Sasol II
Dry Basis
    Ash                           35.9  %          27   %
    Volatlles                     22.3            25
    Fixed Carbon                  41.8            48

Ultimate Analysis as Received
    Carbon                        45.4  %          54.2 %
    Sulfur                         0.4              1.1
    Nitrogen                       1.1              1.3
    Hydrogen                       2.5              2.9
    Oxygen                         7.9              9.4
    Ash                           32.0            25.6
    Moisture                      10.7              5.5
         Total                   100.0  %          100.0 X

Ash Properties
    Softening Point           2440°F (1340°C) 2350°F (1290°C)
    Melting Point             2600°F (1430°C) 2430°F (1330°C)
    Fluid Point               2690*F (1475°C) 2480°F (1360°C)

Gross Heating Value (dry)      8,380 Btu/lb    10,300 Btu/lb
                             (19,480 kJ/kg)   (23,940 kj/kg)
                             12

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Surface conveyor belts transport the coal  from the  storage  bunkers  to  the
secondary crushers and screens.   The final  product  consists of two  coal
sizes, less than 0.4 Inch (1  cm) and between 0.4 and 2  Inches  (1  and 5 cm),
which are transferred separately on twin conveyors  to the 60,000  ton
(54,000 mt) Sasol factory storage bunkers.  Coal Is kept damp  on  the con-
veyor belts by water sprays at suitable points to prevent dust formation.
The less than 0.4 Inch (1 cm) fraction (approximately SOX of the  total)
1s used 1n the power plant to produce electric power and heat  for steam
production, whereas, the 0.4 to 2 Inch (1 to 5 cm)  fraction Is fed to  the
Lurgl gaslfiers.

      The  Lurgl  pressure  gaslfiers are fixed-bed, water-cooled reactors
 that gasify  the coal  In  the  presence of oxygen  and  steam to yield a syn-
 thesis  gas containing methane,  carbon monoxide, hydrogen, carbon dioxide,
 ammonia,  hydrogen  sulflde, steam, and numerous  other compounds.  Lurgl
 pressure  gaslfiers were  selected because they had already  been demonstrated
 1n smaller sized Installations  and  had the advantage of being able to
 work on the  rather low grade, high ash coal available to Sasol I.  The
 fact that they  operated  at a pressure of approximately  350 ps1 (2400  kPa)
 which was also  the desired operating pressure  for  the Flscher-Tropsch plant
 was  an  additional  advantage.

      Thirteen Lurgl gaslfiers consume coal  at a total  rate of approximately
 8,000 tons (7300 mt) per day.   These gaslfiers are 12  feet (3.7  m) 1n
 diameter  and are the largest of their kind In commercial operation.   On an
 annual  basis, 10.8 out of 13 gaslfiers  are In service.   At this  level, gas
 production 1s actually limited  not by gasification but rather by gas
 purification capacities.  The Lurgl  gaslfiers operate  on the  principle of
 countercurrent flow of coal  to  steam and oxygen which  offers  the best
 conditions for heat and  mass transfer and optimum  efficiency. The overall
 thermal efficiency of the gaslfler system 1s approximately 75.5%.   Gasi-
 fication occurs at 1800°F (1000°C).

      Consumption of oxygen and steam 1n the Lurgl  gaslfiers 1s a function
 of a number of variables, but typical Sasol values are 220 standard  (0°C,
                                          o
 1 atm) cubic feet  (SCF)  of oxygen (6.2 Mm) and 62 pounds  (28 kg) of steam
                    •5
 per 1000 SCF (28 Mm  ) of raw synthesis gas produced.  Raw gas production

                                     13

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averages 330 million SCF (9.3 million  Mm )  per day.   Oxygen  Is  produced  In
one of the world's largest air separation plants.  About  13,000 tons
(12,000 mt) of air are compressed and  cooled  down  to  -310°F  (-190°C)  every
day In order to separate the oxygen and nitrogen and  recover them 1n  liquid
form.  The oxygen Is used 1n the Lurgl gaslffers as well  as  1n  the partial
oxidation methane reforming plant.  The nitrogen Is used  1n  an  ammonia plant.

     Steam and electricity are generated In a power plant which consumes
approximately 7,000 tons (6400 mt) of  coal  per day or 50% of the coal
supplied to the Sasol  I plant.  Conventional  pulverized fuel  boilers  are
used.  The steam generated Is used not only for the gasification of coal,
but also 1n the various plants Inside  and outside  the Sasol  complex.

     Sasol I coal contains 30 to 35% ash which must be disposed of.  The
residual carbon 1s completely burned out of the ash with  oxygen 1n the
combustion zone at the bottom of the Lurgl  gaslflers.  This  exothermic
reaction helps supply the heat for the endothermic gasification reaction
In the upper part of the gaslflers.  The residue 1s  essentially burned-out
ash which  Is transported from the gasification and power plant areas  by
water In a low velocity sluiceway to the ash  dewaterlng unit.  Coarse
ash  1s removed by conveyor belts to an ash dump.  The fine ash 1s concen-
trated 1n  a thickener and the concentrated fine ash 1s then dewatered 1n
a  slimes dam.  The ash contains soluble  Inorganic salts that will leach
out.  The  ash system 1s however an evaporative  system for water and re-
quires water make-up and no  purge.  Hater drainage from the slimes dam
1s collected and  pumped back Into the ash sluiceway system.   To prevent
water seepage, the slimes dam was given  an Impervious clay layer  from
clay available on site.  The slimes dam  was  built with an extensive drain-
age  system to recover all seepage for return to the ash sluiceway system.
Coarse ash contains no  excess water and  at least the outside of the
dump soon  dries out to  such  an  extent that It will absorb rain water.
No evidence of seepage  from  the ash dump has  been found and no measures
are  taken  against seepage.   Success has  been  achieved  In  growing  grass
on the  dumps  to make  them aesthetically  acceptable.  Regular samples of
water  from boreholes  1n  the  vicinity  of  Sasolburg have been  taken over
the  years  and  no  evidence of underground water  pollution  has been found.
                                    14

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     Raw synthesis gas leaving  the  top of the gaslflers contains apart
from carbon monoxide and hydrogen appreciable quantities of methane, car-
bon dioxide, hydrogen sulflde,  and  undecomposed steam.  In addition, the
gas contains cyanide compounds, tars, oils,  phenols, organic sulfur com-
pounds, and numerous other Impurities 1n minor quantities.  The Iron-
containing Flscher-Tropsch catalyst Is very  sensitive to sulfur, cyanide,
and other compounds.  Efficient purification of the synthesis gas  Is an
essential requirement for high  Flscher-Tropsch conversion rates.   In
addition, the raw gas contains  about 30% carbon dioxide which must be
brought down to a lower level.

     After separation of entrained  coal dust, the raw synthesis gas 1s
cooled 1n a sequence of waste heat  boilers and condensers.  The raw gas
contains large quantities of undecomposed gasification  steam.  During gas
cooling this steam Is condensed and the resulting aqueous 11quor contains
the water-soluble components that were  1n the gas, chiefly  phenols and
ammonia.  The tars and oils are also separated  from the synthesis  gas
during cooling.  The oil and aqueous liquor  streams are fed to tar distilla-
tion and Phenosolvan plants respectively.   In  the tar distillation plant,
road primer, creosotes, and lighter naphthas fractions  are  separated.   The
naphthas are hydrogenated and distilled  to  produce benzoles for  solvent use
and for blending Into gasoline.  In the Phenosolvan plant,  the aqueous  liquor
Is treated by solvent extraction with an  oxygen-containing  organic solvent,
butyl acetate, to remove the phenol compounds.   The ammonia Is then  recovered
by stripping with steam and converted to ammonium sulfate for fertilizer
manufacture.  There are 5.5 U.S. gallons  of tar and oil and 17 pounds  of
ammonia recovered per short ton of coal  gasified  (23 liters and  8.5  kg per mt),

     Stripped liquor, containing approximately 240 and 250 parts per million
 (ppm) of ammonia  and  phenol, Is processed In a conventional biological  treat-
ment plant  together with  effluents  from other chemical  plants In the area, as
well as  domestic  sewage from the town of Sasolburg.  Treated liquor 1s used
 1n  the  factory  for  removal and transport of ash  from the gaslflers.   Ash acts
 as  an  adsorbent,  reducing the  residual oil  content of treated liquor to less
 than 2.5  ppm.

                                     15

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     Cooled synthesis gas leaving the waste heat boilers and condensers
still contain Impurities, Including carbon dioxide, hydrogen sulflde,  and
an array of gum-forming compounds.  These Impurities are removed by
methanol In the Rectlsol plant.  The Rectlsol  process 1s based on the
capability of one solvent, cold methanol, to absorb all  Impurities present
In gases from coal gasification tn a single process step.  Since the ab-
sorption capacity of methanol Increases with decreasing temperature, the
raw gas 1s contacted and scrubbed with liquid methanol at -67°F (-55°C).

     At Sasol I, the Rectlsol process (a total of four parallel streams) has
a long term on stream record of 97%, and produces a purified gas containing
1.51 carbon dioxide and 0.07 ppm hydrogen sulflde.  A typical composition
of raw and pure synthesis gas Is shown In Table 2.  The extremely pure gas
from the Rectlsol process 1s suitable for the sensitive Flscher-Tropsch
synthesis catalyst.  The main energy consumption In the Rectlsol unit 1s
that used to drive the methanol circulation pumps and the refrigeration
compressors.  Approximately 0.9 KWH and 4.6 pounds  (2 kg) of steam per
1000 SCF (28 Nm3) of purified gas leaving the Rectlsol process are required.

     The off-gas  (containing carbon dioxide and hydrogen sulflde) from the
Rectlsol plant 1s used as an expansion gas.  Before this gas 1s vented to
the atmosphere, hydrogen sulflde  1s removed and recovered as elemental
sulfur  1n a Stretford sulfur recovery unit.   The Stretford  unit was
Installed In 1976.  The  limit  set for gaseous effluents  from the Stretford
units both at Sasol I and Sasol II 1s 50 ppm  hydrogen sulflde.  Some hydro-
carbons and other Impurities are  still present 1n the vent  gas.

     The purified gas emerging from the Rectlsol plant undergoes the
Flscher-Tropsch synthesis which produces hydrocarbons by the catalytic
conversion of carbon dioxide and  hydrogen according to the  following
equation:
         n(CO + 2H2)   -*•    (-CH2-)n + nH20
                                    16

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         Table 2.  Typical  Composition of Raw and Pure
                   Synthesis Gas (Volume %)
Component                        Raw Gas           Pure Gas
   C02                            31.4                1.2
   H2                             40.2               54.0
   CO                             17.1               30.5
   CH4                            10.2               13.6
   H2S                             0.3
   N2+Ar                           0.4                0.6
                                   0.4                0.1
                              17

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Two types of Flscher-Tropsch reactors are used,  the German developed fixed
bed process (Arge) and the American fluid bed  system (Synthol).  The
purified gas from the Rectlsol  plant 1s divided  Into two streams.   The
larger stream Is fed directly to the fixed bed Arge synthesis  units where
a stationary pellet1zed catalyst Is used.  The gas conversion  Is not
complete.  The tall gas from the Arge units contains 1ow-bo1l1ng hydro-
carbons and carbon dioxide.  These are removed In a Rectlsol wash  unit
at subzero temperatures.  The washed gas together with the remainder of
the fresh gas from the purification plant enters a reforming plant where
methane Is reacted with steam and oxygen over  a  nickel catalyst to produce
additional carbon monoxide and hydrogen.  After  adjustment of  the  hydrogen-
carbon monoxide ratio, the gas 1s fed to the fluid bed Synthol plant where
a circulating powdered catalyst 1s used.  The tall gas of this plant  Is
also recycled to the reforming units after removal of carbon dioxide.
For both the Arge and Synthol plants there are recovery and refining
plants downstream.

     The fixed bed reactor produces In general straight-chain  hydrocarbons
with a high average molecular weight In the range of dlesel oil and
parafln waxes and a relatively low percentage of gasoline,  liquefied
petroleum gas, and oxygenated compounds (alcohols, ketones,  organic adds),
The fluid bed process produces branched oleflns  of a lower average molecu-
lar weight 1n the range of liquefied petroleum gas and gasoline, little
h1gh-bo111ng material, and some oxygenated products (Table 3).  Although
the basic chemistry for both reactors Is the same, the different tempera-
tures, method of catalyst contacting, recycle ratios, feed gas composi-
tions, and hydrogen partial pressures employed 1n the two systems result
not only  1n a difference In product selectivity,  but also 1n  a difference
1n the properties of  hydrocarbons within the same boiling range.   In
general,  the higher the reaction temperature the  higher the content of
oleflns and the  lower the average molecular weight of the products.
                                    18

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             Table 3.   Comparison of  Fixed Bed and Fluid Bed
                       Conditions and Products

                                     Fixed Bed             Fluid Bed
Conditions
     Temperature                 430-490°F (220-255°C)    625°F (330°C)
     Pressure                     360 pslg (2500 kPa)     330 pslg (2300 kPa)
     CO + H2 Conversion,  %               65                    85
     H2/CO Ratio 1n Feed                 1.7                   2.8

Product Composition. Vol  %
     Liquefied Petroleum  Gas  (C3-C4)     5.6                   7.7
     Petroleum (Cg-C^)                 33.4                  72.3
     Middle 011s (dlesel, furnace)      16.6                   3.4
     Waxy Oil                           10.3                   3.0
     Medium Wax, mp 135-140°F (59°C)    11.8
     Hard Wax, mp 203-206°F (96°C)      18.0
     Alcohols and Ketones               4.3                  12.6
     Organic Acids                     trace                  1.0

Product Selectivity, Vol  %        C5-C,2   C13-C18      C5-C10   Cn-C14
     Paraffins                       53        65          13        15
     Oleflns                         40        28          70        60
     Aroma tics                       0         0           5        15
     Alcohols                        66           65
     Carbonyls                       11           65
                                   19

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     The fixed bed Arge system (a joint development of Ruhrchenrie and  Lurgl
of Germany) consists of five reactors  In parallel,  each with a shell of
approximately 10 feet (3 m) In diameter and a  height of 42  feet  (13 m).
Inside each shell there are 2,000 vertical  tubes, 2 Inches  (5 cm) In
diameter, containing the pelletlzed Iron catalyst.   The tubes are surrounded
on the shell side by a steam jacket.  The gas  Is passed over the catalyst
from top to bottom and the heat released by the exothermic  reaction 1s
absorbed by boiling the water In the shell. The reaction temperature  Is
controlled by controlling the pressure of the  boiling water.  The Flscher-
Tropsch reactions are highly exothermic, and one of the major design
problems for both the Arge and Synthol systems Is adequate  heat  removal
from the reactor.  About 7,500 Btu's of heat are released per pound of
product (17,400 kJ/kg).

     Figure 3 Is a schematic drawing of the fixed bed Arge  reactor.   The
reactor operates at 360 pslg (2500 kPa).  The  life  of the  Iron catalyst 1s
six months during which time the operating temperature 1s  Increased  from
the starting point of 430°F (220°C) to a maximum of 490°F (255°C).   The
specific catalyst employed contains a number of promoters  (Including copper
and potassium) and has to be partially reduced before It can  be  used.  It
1s manufactured at Sasol.

     The fixed bed synthesis accounts for about one-third of Sasol  I's
plant output.  It came on line In 1955 with only minor problems  and behaved
more or less as designed.  Production up to 140% of the design capacity
has been achieved.  The major disadvantage of the  Arge reactor system 1s
Its limited scale-up potential.  New, large synthetic fuel  plants would
require an  Impractical number of such reactors.

     The synthesis products exit at the bottom of the Arge reactor.   The
tall gas 1s separated from the heaviest hydrocarbons which are obtained as
reactor condensate.  The hot gas then exchanges heat with the Incoming
feed gas and Is  further cooled and washed with sodium hydroxide solution
In water-cooled  condensers.  The heat exchangers and the condensers
produce  hydrocarbon and aqueous condensates which are, after pressure
release and recovery of  the dissolved gas, sent to  the refinery.

                                    20

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  STEAM
COLLECTOR
TUBE BUNDLE
GAS INLET

     STEAM HEATER



  •-  STEAM OUTLET


     FEEDWATER INLET
                                                   INNER SHELL
                                               »~GAS OUTLET
                                             *" WAX OUTLET
                    Figure 3.   Fixed Bed Arge Reactor
                                 21

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     The tall gas leaving the condensers  Is  used  for  recycle, sold as
Industrial  gas, or Is sent to a  methane reformer.  The tall gas contains
low-boiling hydrocarbons up to pentane, Inclusively,  and  carbon dioxide.
The hydrocarbons are removed In  a Rectlsol wash unit  by heptane at -30°F
(-35°C). followed by a methanol  wash at -40°F (-40°C) to  prevent  a buildup
of carbon dioxide.  The washed gas together  with  fresh gas  from the  purifi-
cation plant and tall gas from the fluid  bed Synthol  reactors 1s  sent  to  a
reforming plant where methane Is reacted  with steam and oxygen over  a  nickel
catalyst at a temperature of about 1800°F (1000°C) to produce additional
carbon monoxide and hydrogen.  The Lurgl  gaslflers and both Hscher-Tropsch
synthesis processes produce methane as the lowest hydrocarbon and there 1s
a tendency for methane to build up 1n the recycle streams.   To make  full
use of the synthesis gas, It Is necessary to reform methane back  to  hydrogen
and carbon monoxide.  Another complication Is the presence  of nitrogen and
argon 1n the synthesis gas, most of which Is Introduced Into  the  gas stream
with the 98% oxygen from the air separation  plant. The nitrogen  and argon
act as Inerts In the system and have to be removed as a purge gas to keep
them within an acceptable level.

     The gas from the reforming plant Is  fed to the fluid bed Synthol  plant.
The Synthol process was developed by M.W. Kellogg of  the  United States.
Each Synthol reactor consists of a feed system, a reactor tube, product-
catalyst separation equipment, and a catalyst recycle hopper (Figure 4).
Fresh feed and recycle gas at 320°F (160aC)  are  blended with finely  divided,
hot 625°F (330°C) Iron catalyst at the base  of the reactor.  This gas-solid
mixture comes rapidly to thermal equilibrium and  rises up the Synthol  reactor
where exothermic Flscher-Tropsch and water-gas shift  reactions take  place.
A significant fraction of the heat liberated Is removed  1n  waste  heat
boilers built Into the reactor.  In addition, the products  and tall  gas
leaving the system at 625°F (330°C) remove a large amount of heat.   The
products are disengaged from the catalyst Initially by gravity and sub-
sequently by cyclone separation.  The gas leaves  the  reactor and  the
recovered catalyst Is collected 1n a settling hopper from which  1t 1s
recycled through a stand pipe and slide valves to the feed gas  Inlet at
the base of the reactor.

                                    22

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   TAIL GAS AND
S?S
SYNTHESIS PRODUCTS'
   CYCLONES
CATALYST SETTLING
     HOPPER
    CATALYST
    STANDPIPE
  SLIDE VALVES
    FRESH FEED
  AND RECYCLE
                                                       COOLING
                                                       OIL OUTLET
                                                             REACTOR
                                                           RISER
                                                  GAS AND CATALYST
                                                  ~    MIXTURE
                    Figure 4.  Fluid Bed Synthol Reactor
                                   23

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     Three parallel  Synthol  reactors  are  1n  operation  at  Sasol  I.   Each has
an Inside diameter of seven  feet (2 m), and  a  height of 120  feet  (37 m).
The reactors operate at 330  pslg (2300 kPa)  and 600 to 625°F (315  to 330°C).
An ammonia synthesis type Iron catalyst containing various structual pro-
motors such as alumina and magnesium  oxide 1s  circulated  through  each
reactor at a rate of 6,000 to 8,000 tons  (5500 to 7000 mt) per hour.   The
reduced Iron catalyst 1s gradually converted during synthesis Into a
mixture of free Iron, Iron carbides,  and  magnetite.  The  catalyst used 1n
the fluid bed reactors was developed  by  Sasol.

     At the time the Synthol  plant was designed only pilot plant data  were
available.  However, when the flutd bed plant  was built,  1t  behaved quite
differently from what was predicted.   Much additional  experimentation,
research, and modifications  were needed at Sasol  before the  fluid  bed
system was developed to the  point where It could be considered completely
reliable.  In contrast to the Arge reactor system, the Synthol  reactors
have distinct scale-up capability and are, therefore,  practical for use
In the large-scale synthesis of hydrocarbons.   Fluid  bed  reactors  will be
used exclusively In Sasol II and III.

     The products of the Synthol reactors and  the tall gas are passed  to a
scrubber where the vapor 1s  cooled from the  reactor outlet temperature of
625°F to 300°F (330 to 150°C).  The higher molecular  weight  hydrocarbons
are condensed and separated.  The heavy hydrocarbons  are  taken off the
bottom of the scrubber and sent to the oil recovery plant.   The vapor  phase
scrubber overhead Is further cooled and sent to a separator  where lighter
hydrocarbons, aqueous chemicals, and  the  gas phase are separated.   The light
hydrocarbon layer Is transferred to  a countercurrent  water-wash tower
where any oxygenated products Including  alcohols, ketones, and organic
adds are washed out.  The washing water  1s  added to  the  aqueous  stream
from the separator and sent to chemical  recovery.  A significant  fraction
of the non-condens1ble product gas from the separator 1s  boosted  to the
reactor Inlet pressure and recycled.   The remaining tall  gas Is washed
with an alkali solution and passed to an  absorption system for recovery
of light  hydrocarbons.   The absorber  effluent  gas  1s  rich 1n methane
and hydrogen.  It 1s either used 1n  ammonia synthesis, sold as Industrial
                                    24

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gas, or reformed to carbon monoxide  and  hydrogen  for  recycle.  When used  1n
ammonia synthesis, hydrogen Is  separated from  the Synthol  tall gas by cool-
1ng to -315°F (-193°C).   The hydrogen  1s then  mixed with a correct amount of
pure compressed nitrogen from the air  separation  plant and converted over
an Iron oxide catalyst to synthetic  ammonia.   The ammonia  1s converted  to
nitrogenous products for use In South  Africa's agricultural Industry.   The
methane fraction from the low temperature hydrogen separation  unit 1s used
as a blending gas to help control the  heating  value of the tall  gas sold
to Industry.  The clean fuel gas supplied to the  nearby Industrial areas
of the Vaal Triangle and the Wltwatersrand has a  heating value of 500 Btu's
per standard cubfc foot (18,600 kJ/Nm ).  To meet the Increasing demand for
Industrial gas, the coal gasification  capacity of Sasol I  was  Increased by
40% 1n the mid-19701s, doubling the supply of gas to  Industry.  The  ex-
pansion consisted of additional gaslflers, a  Rectlsol purification unit,
additional oxygen capacity, and an aqueous liquor purification unit.

     With  the building of Sasol I, the South  African petrochemical Industry
was firmly established.  The solid hydrocarbons from the fixed bed process
find many  applications.  The primary gasoline produced 1s a suitable motor
fuel and the dlesel oil Is of an excellent quality.  The liquid oleffns
provide raw materials for biologically soft detergents, and a wide range
of  high-viscosity,  stable, lubricating oils.   In addition, alcohols,
ketones, aldehydes, organic adds, and esters are recovered from the
aqueous streams  that  flow from  the synthesis  reactors.  A partial 11st of
Sasol  products  1s  presented 1n  Table 4.   The  overall  thermal  efficiency
of  the Sasol  process  from coal  as mined  to saleable  refined end products
1s  35  to 40%.

4.2 Sasol II and Sasol  III
      Early in  1980, South  Africa's  production of gaseous  and  liquid hydro-
carbons from  coal  will  triple  with  the  startup of Sasol II, a $2.8 billion
complex based on the same coal  conversion and Fischer-Tropsch technology
as  Sasol  I.   Sasol  I  and  II will  produce enough  gasoline  to meet 30 to 40%
of  South  Africa's needs,
                                     25

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            Table 4.  Sasol Products and Intermediates
Carbon Dioxide
Oxygen
Nitrogen
Steam
Electricity
Ammonia
Ammonium Nitrate
Ammonium Sulfate
Phenol
Benzene
Toluene
Road  Primer
Fuel  Oil
Xylenol
Light Naptha
Heavy Naptha
Reactor Wax
Soft Waxes
Medium Waxes
Hard Waxes
Paraffin
Gasoline
Diesel 011
Creosote
Liquefied Petroleum Gas
Industrial Gas
Acetone
Methyl Ethyl Ketone
Higher Ketones
Methanol
Ethanol
Higher Alcohols
Ethylene
Butadiene
Styrene
Pitch
                                 26

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     Sasol II will  concentrate on the manufacture of refined motor fuel
rather than petrochemicals, although petrochemicals will  be produced.  The
grass roots plant will produce 2.4 million tons (2.1 million mt) per year
of saleable products, Including 1.7 million tons (1.5 million mt) per  year
of gasoline and dlesel oil.  Sasol II Is being financed by gasoline levies,
suppliers' credits, and government-voted money.  The rising cost of crude
oil should make Sasol II economically very attractive when It comes on
stream 1n 1980.  This has been the case with Sasol I 1n recent years.
Sasol production costs amount to $17 per barrel.  This Is well below the
OPEC price of around $20 per barrel and much less than the $31 per barrel
that South Africa has to pay on the spot market.  Gasoline sells for about
$2.40 a gallon (63
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     The total amount of coal  consumed by Sasol  II will  be approximately
14 million tons (12.8 million  mt) per year of which 9.2  million tons (8.4
million mt) will  be gasified and 4.8 million tons (4.4 million mt)  used for
steam and power production. The steam production will be between four and
five million pounds (about 2 million kg) per hour and the power produc-
tion will be 240 megawatts. Additional power will be bought from the pub-
lic utility system which operates large power plants 1n  the Sasol II area.

     Coal for Sasol II Is higher 1n carbon and lower 1n  ash than Sasol I
coal (Table 1).  Since Sasol II coal Is very friable, crushing and screen-
Ing to the same size as for Sasol I would result 1n a higher proportion
of fines than Is desirable for gasification.  Fines In coal fed to the
gaslflers can be carried out with the raw synthesis gas  and be not only
a loss to the process but result 1n underslrable problems with the gasi-
fication by-products.  Wet screening of Sasol II coal will permit a sharp
separation of the  fines.  The fines will be used 1n the generation of steam
and power for Sasol  II.   In fact, the amount of  power production was chosen
to arrive at a balance between fine and coarse coal.

     The coarser coal 1s  fed to  the coal gasification plant.   The choice
as to which gasification  system  to use was  between  the  Lurgl  pressure
gaslfler with which  Sasol  1s completely  familiar and  a  high  temperature,
low pressure  entrained gaslfler  system using  pulverized coal.  As  a
result of  the  high temperature,  the latter  system does  not produce  coal
gasification  by-products, nor does  1t  produce methane,  but Its oxygen
consumption  1s  high  and  the raw  gas needs compression to  bring It to an
acceptable level  for purification.  The  Lurgl pressure  gasification  has
 the advantage for  the Sasol objective  that  gas  Is  produced approximately
at the  pressure  required for  the Flscher-Tropsch synthesis so that  com-
 pression of large volumes of  raw gas  Is  not required.  In a large  plant
 such  as  Sasol  II,  processing  facilities for the gasification by-products
 can  be  economically  justified especially where  the overall objective of
 the plant Is to produce  hydrocarbons.   All  these considerations expressed
 In terms of capital  Investment,  operating cost  and Income Indicated  that
                                     28

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for Sasol II* Lurgl gaslflers will  again be used.   Over the  years  a  number
of Improvements to the Lurgl  gaslfier have been made allowing the  extra-
polation to larger capacity within  the limits of confidence.  Sasol  II
will require 13,000 tons (12,000 mt)  of oxygen per day from  air separation
plants.

     For the gas purification section, a large number of options were
available to remove not only the last traces of tar and tar  products but
also organic sulfur and hydrogen sulflde as well as carbon dioxide.   Only
the Rectlsol process with methanol  could do all these things 1n one  single
module.  Although  the objectives of  the  purification  sections of  Sasol I
and II are the same, differences In the processing schemes do exist.  For
example, Sasol II will recover ammonia as anhydrous ammonia  while Sasol  I
reacts ammonia vapors with sulfurlc acid to produce ammonium sulfate.
Also, Sasol  II will make more use of air cooling.

     The purified gas from the Rectlsol process, containing less than 0.07
ppm sulfur,  1s sent to the Flscher-Tropsch synthesis.  Sasol I has two
types of synthesis:  a fixed bed system which  produces a high percent of
heavier  paraffin hydrocarbons for which a low  volume market exists and a
fluid  bed  system which produces more oleflns and lighter hydrocarbons In
the gasoline and dlesel range.  The  fixed bed  reactors have the draw-back
that their  possibilities for scale up are limited and  their total capacity
1s  small.   At  Sasol I, a reactor containing  2,000 tubes has a capacity of
approximately  18,000  tons  (16,000 mt) of product  per  year.   Sasol II will
produce  1.7 million tons  (1.5 million mt)  per  year.   The  fluid  bed  reactor
does not have  such size limitations  and can  be confidently  scaled up using
well known  technology.  Since the objective  of Sasol  II  Is  to  produce motor
fuel,  only fluid  bed  reactors will be  installed.   Sasol  II  will contain
seven  fluid bed reactors.   More  motor fuel  per ton  (0.9 mt)  of coal  will be
produced by Sasol  II  (1.78 barrels)  than by  Sasol  I (1.26 barrels)  since a
smaller amount of other products  (waxes, heavy hydrocarbons)  will be pro-
duced  at Sasol  II.

      The synthesis flow scheme  for Sasol  II  is similar to that for  the  fluid
 bed reactors in  Sasol  I with the sequence of operations the same  but the
                                     29

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details of auxiliary processes different.  In addition,  product recovery
and refining are markedly different from Sasol I.   In designing these
operations, advantage has been taken of the experience gained at Sasol  I
and the most modern techniques of gaseous and liquid hydrocarbon process-
Ing.

     At Sasol I, after cooling of the product gas, most  of the non-condensed
hydrocarbon products are recovered In an oil-wash  system and the tall gas
1s used for pipeline gas or reformed back to hydrogen and carbon monoxide.
Recovery of ethylene Is low with most remaining 1n the tall gas.  A low
temperature Rectlsol wash 1s used to remove carbon dioxide from the re-
cycled synthesis tall gas.  In the Sasol II plant, a more efficient hot
potassium carbonate absorption will be used for removal  of carbon dioxide.
Also, the oil-wash system will be replaced by a low temperature unit which
recovers as separate streams a light oil, a propane/butane stream, an
ethane/ethylene stream, a stream of approximately 90% methane and a hy-
drogen rich stream.  The ethane/ethylene fraction goes to an ethylene plant
where the ethylene Is recovered and the ethane recycled and cracked pro-
ducing additional ethylene.  The hydrogen rich stream Is recycled to the
Synthol reactors or 1s used for refinery operations.  Part of the methane
Is used as Internal fuel gas for the plant complex but the major portion
Is reformed  by  partial oxidation to hydrogen  and carbon monoxide for recycle.

     The product refinery 1s geared to  the  South African market which
requires mainly motor fuels, the majority  In  the gasoline  range.  The
light oleflns are combined  by  polymerization  and the polymer  product will
be  partly  hydrogenated to limit the final olefin content In the gasoline.
The  above  400°F (200°C)  material will  be cracked to  produce dlesel oil  and
some gasoline fractions.  The  gasoline  components  will  be  blended to  regular
and  premium  gasoline.  Sasol  II will  produce  the equivalent of  a 40,000
barrel  per day  crude oil  refinery.

     Sasol  II will  be  situated upstream of the large populated Ultwater-
srand  area.   The plant  1s  being designed for maximum re-use  of water within
the plant  and zero  discharge  to local  drainage systems.  The two main

                                     30

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sources of effluent are gasification which  produces an aqueous liquor and
Flscher-Tropsch synthesis which  produces a  watery effluent containing
soluble oxygenates and organic acids.   The  aqueous liquor 1s  first treated
1n a Phenosolvan plant where by  extraction  with  1sopropylether the water
soluble phenols are recovered as a crude tar add fraction and amnonla  Is
stripped off the liquor and further purified by  absorption.   The  Flscher-
Tropsch reaction water Is stripped of  Its non-acid chemicals  which are
recovered as marketable products such  as ethanol, propanol, and acetone.
The remaining effluent, containing organic  acids,  and the stripped aqueous
liquor are then biologically treated In activated sludge units and further
purified by 1on exchangers and activated carbon  to a  purity where they can
be used as cooling water make up.  A purge  stream from  the cooling water
system 1s used for hydraulic ash transport  to the ash dewaterlng  unit.
The ash dewaterlng unit 1s an evaporative  system Involving a  lined  slimes
dam and an ash dump.  Total water Input to  the plant to replace losses
and evaporation 1s In the range of 14,000  to 15,000 gallons  per  minute
(3200 to 3400 m /h).  Gaseous effluents must conform to South African codes.
Power plant stacks will be about 500 feet  (150 m)  high for dispersion of
boiler flue gas and Stretford process emission.

     Sasol II 1s scheduled for completion  early In  1980.  As  soon as Sasol
II Is finished construction will start nearby on Sasol  III.   The decision
to build Sasol II was made 1n 1979 after the new government  1n Iran
decided to cut off oil supplies to South Africa.  Iran had been South
Africa's principle supplier.  In order to  save time and design costs,
Sasol  III will be almost  an exact copy of  Sasol  II and will  cost $3.8
billion.  Once the three  plants are 1n operation, they will  produce about
112,000 barrels of oil per day, approximately half of South Africa's
needs  1n the  1980's.   The three Sasol  plants will  decrease South Africa's
dependence on Imported oil; they will  strengthen the base of the South
African motor fuels and  chemical  Industry;  they will make a significant
contribution  to the saving of foreign  exchange; they will provide a large
number of job opportunities not only  1n the plants themselves but also 1n
all  the  supporting  services and  Industries for all groups of the South
African community;  and they will  set  a new standard  1n  general for  the coal
conversion  Industry which can be  considered as a target for  second  genera-
tion processes  to  Improve upon.
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                              5.   Conclusions

     The economic conditions for  an oil-front-coal  plant differ  from country
to country especially since the viability and  degree  of risk  depend so much
on non-technical  factors such as  government policy toward  such  a venture.
The making of synthetic oil from  coal  works In South  Africa because of a
unique combination of factors Including the availability of vast reserves
of low cost coal, the scarcity of domestic petroleum  resources, and the
abundance of cheap labor.  South  Africa has coal  reserves  of  25 billion
tons (23 billion mt).  Almost 802 of South Africa's energy needs are  met
by utilizing coal.  South Africa  Is boycotted by most of OPEC and  1s
without oil reserves of Its own.   Therefore, South Africa  has utilized
technologies Invented 1n Europe and the United States to convert Us
abundant coal resources to the forms of fuels and petrochemicals  required
by a highly technical society.

     The United States has seven times the coal reserves of South Africa
and a diminishing supply of domestic petroleum resources.  Recent develop-
ments 1n the worldwide energy situation, especially the systematic OPEC
price Increases,  have caused many Americans to express Interest In Sasol-
type coal-to-oll  projects.  There  are,  however, doubts about the economic
feasibility of a  Sasol-like plant for the  United States.  Comparisons are
difficult  because of the number of  factors  Involved  Including  the cost of
coal, construction,  and labor.   It  has  been estimated  that oil could not
be  produced from  coal 1n the United States  for less  than $27 per barrel
and  perhaps as much  as  $45, compared with  around  $20 per barrel currently
charged  by OPEC.   In addition, there are doubts about  the complexity and
high capital costs  Involved 1n scaling  up  such a  process to meet American
needs.   South Africa 1s  currently spending between six and seven billion
dollars  to Increase  Its  synthetic oil  production  to  112,000  barrels per
day.  This would  be  a  drop 1n  the oil  bucket  1n the  United States which
uses  17.6  million barrels  per  day.   Considering South  Africa's gross
national  product and energy consumption,  Its  effort  1s comparable to a
 $300 billion crash program for the United  States.
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     Sasol's success Indicates that producing synthetic fuels from coal
can be technically and economically feasible.  The technology 1s available
and the Sasol process - coal gasification plus Fischer-Tropsch synthesis -
1s the only commercially proven process that will produce synthetic fuels
quickly, on schedule, and at predictable costs.
                                     33

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                             6.   References

1.   Fluor Technical  Dept., "Coal  Liquefaction Technology",  SFR-103.

2.   Fo1s1e, Jack, "S. Africa Holds Lead 1n  Making 011  From  Coal",  Los
     Angeles Times, July 30, 1979.

3.   Hoogendoorn, J.C., "Gas from Coal  for Synthesis of Hydrocarbons",
     Ninth Synthetic Pipeline Gas Symposium, Chicago, October 31  -
     November 2, 1977.

4.   Hoogendoorn, J.C., "The Sasol Story", American Institute of Mining,
     Metallurgical and Petroleum Engineers, 23rd Annual Meeting, Dallas,
     February 24, 1974.

5.   Klrk-Othmer, "Carbon Monoxide - Hydrogen Reactions", Encyclopedia
     of Chemical Technology, 2nd Ed., Vol. 4, pp. 468 - 477.

6.   Kronseder, John G., "Sasol  II: South Africa's 011-from-Coal Plant",
     Hydrocarbon Processing, July 1976, p. 56F.

7.   Mclver, Alan E.,  "Sasol: Processing Coal Into Fuels and Chemicals
     for  the South African  Coal, 011 and Gas Corporation", Second Annual
     Symposium  on Coal Gasification, Liquefaction, and Utilization, Best
     Prospects  for Commercialization, Pittsburgh, August 5-7, 1975.

8.   "011  from  Coal  -  How  South Africa's Sasol Coal Conversion Plant
     Operates", World  Coal, April  1975, pp.  18-19.

9.   Rudolph,  Paul  F.H.,  "Coal Gasification  - A  Key for Coal Conversion",
     American  Institute of Mining,  Metallurgical  and Petroleum Engineers,
     23rd Annual  Meeting,  Dallas,  February  24, 1974.
                                    34

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                          6.   References  (Cont'd)

10.   "South Africa Details Its Second  Sasol  Project", Coal Age, February
      1975. pp. 82-93.

11•   "Synfuel Success: Alchemy 1n South  Africa",  Time, August 20, 1979,
      P. 42.

12.   "Synthetic Chemicals 1n South Africa",  Science,  August  17, 1979,
      p. 649.
                                    35

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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO. 2.
EPA- 600/8-80-002
4. TITLE ANDSUBTITLE
SASOL: South Africa's Oil from Coal Story— Back-
ground for Environmental Assessment
7. AUTHOR(S)
J.L. Anastasi
9. PERFORMING ORGANIZATION NAME AND ADDRESS
TRW Environmental Engineering Division
One Space Park
Redondo Beach, California 90278
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
3. RECIPIENT'S ACCESSION NO.
6. REPORT DATE
Januarv 1980
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
INE825
11. CONTRACT/GRANT NO.
68-02-2635
13. TYPE OF REPORT AND PERIOD COVERED
Final; 7-8/79
14. SPONSORING AGENCY CODE
EPA/600/13
,B. SUPPLEMENTARY NOTES IERL.RTp project officer is William J. Rhodes , Mail Drop 61,
919/541-2851.
 . ABSTRACT
              report describes the world's only oil-from-coal plant, known as
SASOL, operated by South Africa since 1955. When almost $1 billion worth of expan-
sion is completed in the early 1980s, three SASOL plants will produce a total of
112,000 barrels of oil per day, or about half of South Africa's needs.  Production
costs average Sl7 per barrel, well below the 1979 OPEC price of more than #20 per
barrel. South African motorists pay about #2.40/gallon (#0. 63/liter)  of gasoline at
the pump. SASOL converts coal to liquid fuels in two steps: (1)  the coal is gasified
with oxygen and steam under pressure to yield a mixture of reactive gases, and (2)
after being  cleaned of impurities ,  the mixture is  passed over  an iron-based cata-
lyst in Fischer-Tropsch synthesis units to produce liquid fuels. SASOL's operation
is helped by South Africa's abundance of cheap labor and low cost coal. The U.S. ,
like South Africa, has vast coal reserves.  Although comparisons are difficult, it has
been estimated that oil could not be produced from coal in the U. S. for less than
gf27 per barrel and perhaps  as much as $45.  The  South African system is the only
commercially proven process for the production of synthetic liquid fuels. The report
provides some of the background on a process that will receive high priority for
environmental assessment.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Pollution
Coal
Coal Gasification
Liquefaction
18. DISTRIBUTION STATEMENT
Release to Public
b.lDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
SASOL Process
19. SECURITY CLASS (This Report}
Unclassified
20. SECURITY CLASS (This page)
Unclassified
c. COSATI Field/Group
13B
08G
13H
07D
21. NO. OF PAGES
39
22. PRICE
EPA form 2220-1 (»-73)
                                          36

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