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The first is the Lurgi process 
mentioned earlier. This is the only 
commercialized process. El Paso 
National Gas Company, Houston, 
Texas, hopes to have a 250 million 
cubic foot (mcf) plant operational 
on a 40,000 acre coal field in New 
Mexico by 1976. The plant is es- 
timated to consume about eight 
million tons of coal per year. In 
the Lurgi process, crushed coal is 
fed by hopper to a high pressure 
— 450 prounds per square inch 
(psi) gasifier where steam and oxy- 
gen are introduced into the mov- 
ing bed of crushed coal. In addi- 
tion to entering into the reaction, 
the steam prevents clinkering of 
the ash, and serves as a cooling 
agent for the rotating grate at the 
bottom of the reactor vessel. Ash 
is removed through an ash lock 
and discharged into a hopper. The 
products are methane and large 
quantities of hydrogen, carbon 
monoxide (CO) and carbon dioxide 
(CO2). The gases are cooled, CO2 is 
removed, and CO and hydrogen are 
converted to methane through a 
methanation process. Early plants 
could only produce gas with a 
heating value of 450 BTU per syn- 
thetic cubic foot (scf). However, on 
August 5, 1974, Lurgi announced 
that the final link in the process 
had been proven and_ pipeline 
quality gas of 950 BTU could now 
be produced. In Illinois, the Lurgi 
process is being examined by 
Commonwealth Edison for power 
plant supply gas (low BTU) for 
the Powerton Station near Peoria. 
The Institute of Gas Technology 
(IGT) Hygas process (Figure 2) 
was developed by the American 
Gas Association Institute of Gas 
Technology in Chicago, Illinois, 
where there has been a plant oper- 
ating since 1971. It is capable of 
producing test quantities of high 
BTU gas by means of a three stage 
fluidized bed process. In this pro- 
cess, hydrogen necessary for the 
TILUINOTS.AUDUB ON) BU 
reaction of coal is produced by 
electrothermal gasification of the 
residual char leaving the primary 
reactor vessel. The finely crushed 
coal is slurried with light oil and 
injected into the upper stage of 
the hydrogasifier. The light oil 
flashes off and is recycled. The coal 
passes through two stages of hy- 
drogasification where it is contact- 
ed with hydrogen-rich gas _ pro- 
duced in the electrothermal gasifier. 
About 60 to 70 percent of the feed- 
stock is converted to gas. The 
spent char discharged from the 
electrothermal gasifier is used for 
power generation to furnish the 
electricity necessary for the hydro- 
gen generation. The product gas 
from the reactor passes through a 
purification train where carbon 
dioxide, liquids, sulfur, and other 
by-products are removed. The mix- 
ture of methane, hydrogen, and 
carbon monoxide from the gas pur- 
ification step then goes through a 
methanation step where the hydro- 
gen and carbon monoxide are con- 
verted to additional methane. The 
final product gas has a heating 
value close to 1000 BTU/scf and 
is at a pressure of 1000 pounds per 
square inch guage. The plant capa- 
city is 1.5 mscf of SNG from 80 
tons of coal per day. 
A third process is the CO2 ac- 
ceptor process being tested by Con- 
solidated Coal Company in a pilot 
plant in Rapid City, South Dakota. 
This is a two stage process for 
sub-bituminous coals and lignite. 
(Figure 3) It uses recycled lime or 
calcined dolomite to remove CO2 
formed in the gasification plant. 
The reaction of the CO2 with the 
lime or dolomite also provides 
heat for the gasificaton reaction. 
Dry lignite is introduced into the 
devolatizer vessel where it is con- 
tacted with hot, hydrogen-rich gas 
from the devolatizer and the gasi- 
fier. The lime or dolomite acceptor 
is introduced into both the devola- 
