PROCESS-DEVELOPMENT OF MILD GASIFICATION FOR MIDWESTERN BITUMINOUS AND WESTERN LOW-RANK COALS

A mild gasification process is under development using a 100 lb h-1 process development unit with a high-sulphur midwestern bituminous coal and a low-rank, low-sulphur western coal, to produce metallurgical coke substitutes, carbon black. activated carbon, diesel fuel additives, chemical feedstock materials, and pure chemicals. The PDU consists of a fast fluidized-bed carbonizer optimized for condensables production and a bubbling fluidized-bed calciner to reduce volatiles and sulphur contents to acceptable levels for metallurgical coke. Condensables are collected in a high-temperature tar venturi scrubber, a sieve tower, and a water venturi scrubber. Chars produced at 1100-degrees-F ranged in volatile matter from 15 wt% for the subbituminous coat to 13 wt% for the bituminous coal. Ash contents were 10 and 19 wt% respectively, and sulphur contents were 0.4 and 3.0 wt% respectively. Three distinct boiling-point fractions of liquids were collected from the condensation train. With subbituminous coal, the tar scrubber yielded liquids ranging in boiling point from 380 to 500-degrees-C, the sieve tower liquids ranging from 200 to 470-degrees-C, and the water scrubber liquids ranging from 170 to 440-degrees-C. With the bituminous coal. the tar scrubber yielded liquids ranging in boiling point from 400 to 510-degrees-C, and the combined sieve tower water scrubber liquids ranging from 170 to 460-degrees-C.