Single retort manufacturing technique for producing valuable char and

Abstract

A single retort and accumulator structure includes two heating zones for successively removing volatile material from dried crushed coal so that the resultant calcined char has less than about 7 weight percent volatile material and is suitable as a raw material for producing formcoke. In the first zone (carbonizing zone) heat carrying solids are introduced with crushed coal to heat the powdered coal to a temperature in the order of about 800.degree. F. to 1000.degree. F. and produce a carbonized char containing about 10% to 20% by weight of volatile material. The resultant carbonized char is fed onto a trommel, or rotating cylindrical or tapered screen, and the char passes through the screen into a calcining fluidized bed zone. The fluidized bed is maintained by upwardly directed jets of an oxygen containing gas and steam. The temperature of the fluidized bed zone is in the vicinity of about 1200.degree. F. to 1600.degree. F. whereby the volatile material content of the particulate char is reduced to about 7 weight percent or less, as it is withdrawn from the fluidized bed. The heat carrying solids which supply heat to the first zone roll over the trommel, and are thereby separated from the powdered carbonized char, so that they may be reheated and used again. The volatile materials generated in the two heating zones are mixed and drawn off through a single outlet.