GB665690A - Improvements in or relating to a method of distilling carbonaceous solids - Google Patents

Abstract

665,690. Distilling carbonaceous solids. PITTSBURGH CONSOLIDATION COAL CO. April 25, 1949 [May 15, 1948], No. 10889/49. Class 55 (i). Carbonaceous solids, e.g. coal, lignite, oil shale, are distilled by contact with reheated distillation residue of which a portion has been burnt to yield a hot flue gas serving to heat the remainder which alone is returned to the retort. A rotary retort 10 as described in Specification 665,681 is charged with coal from a hopper 12 and previously distilled material through a screw feeder 15 at a rate and temperature such that residue picked up by lifters 20 and discharged through a screw feeder 24 still contains volatile components. Vapours separated from the residue pass to a condenser 32 and solids in part to storage and the rest to a conduit 46 to which flue gas from a combustion zone 65 is introduced. The residue at 1400‹ F. or more passes through a separator 48 whence a portion is returned to the retort, flue gas and evolved volatiles being conducted to a second separator 56. The remainder of the residue from the separators is fed through a conduit 64 to the combustion conduit 65, air being admitted through a pipe 74. The flue gas obtained may be circulated in indirect heat exchange with the residue which may be conveyed by only a portion or by a readily movable gas such as superheated steam or carbon dioxide. A retort temperature of 800-1400‹ F. for the low temperature distillation of high volatile bituminous coal is obtained by adjustment of the amount and temperature of the residue returned to the retort.