3194. SINGH, A. D. Fluidized-Coal Devolatilization. Power Plant Eng., vol. 51, No. 10, 1947, pp. 112-115.
Term “fluid devolatilization” is applied to the distillation of gas from coal fluidized by passage of gas or steam through a bed of the finely divided material. Pulverized coal is screw-fed from a hopper into pipes through which steam or recycled gas produced in the process flows fast enough to prevent settling of the largest particles. The coal is carried thus into a vertical, electrically heated retort. Tar vapor and gas are quickly evolved, and agglomeration of the char occurs only to a slight extent owing to preliminary oxidation of the coal and recirculation of about the same weight of char as that of the coal fed to the retort. The char is recovered by cyclone separators, and the tar vapor and gas pass to a cooling and condensing system for byproduct recovery. Heat transfer in the fluidized material may be nearly 6 times that of conventional coking, probably owing tot he scrubbing action on the gas films surrounding the particles. Char leaving the fluidizer system at temperatures in the range 700°-800° should be an ideal fuel for cyclone burners, making possible very high rates of heat release. From 4-6% can be added to the overall heat recovery by the elimination of stack losses associated with the combustion of H2. Char of 12,180 B.t.u. per lb. can be obtained from 11,460 B.t.u. coal, in addition to 9,300-16,600 cu. ft. of fuel gas and 14 gal. of tar per ton of coal. S is removed from the coal by the process.