Assessment of technology for the liquefaction of coal

Technical Report · Thu Dec 01 00:00:00 EST 1977

DOI:https://doi.org/10.2172/7049743· OSTI ID:7049743

Of the four general methods of coal liquefaction, only indirect liquefaction (Fischer-Tropsch and methanol synthesis) currently is practiced on a commercial scale. Indirect liquefaction requires complex and expensive plants. Since the thermal efficiency of existing indirect liquefaction plants is 40 to 45 percent, coal consumption is very high. Pyrolysis processes for coal liquefaction produce gas, heavy liquids, and char; the heavy liquids require hydrogenation, and the char requires gasificationif clean fuels are to be produced. Pyrolysis does not appear promising for meeting the large liquid fuel requirements of the United States. The other two methods of coal liquefaction, solvent extraction and catalytic liquefaction, have been studied in a number of process configurations. These process schemes have resulted in thermal efficiencies of 60 to 65 percent and have produced 2 to 2.7 barrels of oil per ton of coal feed. At their present stage of development, there are difficult filtration requirements and, therefore, only those schemes yielding a product that can be recovered by vacuum distillation seem to be practical. A simple, economic method of separating unconverted coal and ash from nondistillate coal liquids remains to be demonstrated. Solvent extraction processes using donor solvents to produce a synthetic crude have been developed through the pilot-plant scale, and at least one process is ready for testing in a plant processing 200 to 600 tons per day. Of the processes for producing synthetic crude or low-sulfur heavy fuel oil by hydrogenation of a slurry of heavy oil and coal in the presence of a solid catalyst, only those in which the catalyst is kept in motion have been developed through the pilot-plant stage. The cost of synthetic crude oil from processes currently developed at least through the pilot-plant scale is estimated to be $20 to $30 per barrel (based on 1976 costs) or about twice the present cost of imported oil. (LTN)

• Research Organization: National Research Council, Washington, D.C. (USA). Ad Hoc Panel on Liquefaction of Coal
• DOE Contract Number: EX-76-C-01-1216
• OSTI ID: 7049743
• Report Number(s): FE-1216-3
• Country of Publication: United States
• Language: English

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