Patent GB-727382-A (GB)
Title: Conversion of carbonaceous solids into volatile products
Inventor: RUSSELL FRANCIS ROBINETT
IPC: C10B49/22
Filed: 1953-08-31
Abstract: 727,382. Carbonizing and gasifying carbonaceous materials. STANDARD OIL DEVELOPMENT CO. Aug. 31, 1953, No. 24019/53. Class 55 (1). Finely divided solid or liquid carbonaceous materials are mixed in an endothermic conversion zone with a dense fluidized bed of hot particles, part or all of the particles withdrawn from the zone being recycled to a combustion zone where they are mixed with different inert particles so that the mixture contains 1-20 per cent carbon, and the hot particles from this zone after separation of inert particles being returned to the conversion zone. Finely divided coal fed by a fluidizing gas such as steam or flue gas into a retort 10 is heated therein to 800-2000‹ F. by combustion residues from a heater 50. Vapours pass off through a line 18 and entrained solids trapped in a separator 16 are returned or discarded. Coke &c. withdrawn through a line 24 passes with fluidizing steam through a line 28 to a water gas generator 34 in which a fluidized bed at 1400-2400‹ F. and atmospheric to 400 lb. per sq. in. pressure is maintained. The carbon concentration is held at 10-50 per cent by adjustment of ash withdrawal through lines 43 or a similar outlet 64 from a combustion heater 50 to which gasification residue suspended in air from a compressor 49 is delivered through a line 48. The combustion zone 54 comprises a dense fluidized bed of non-combustible material, e.g. sand of larger size than the gasification residue, and temperatures of 1500‹ F. or more, generally 1600-2300‹ F., are maintained with a carbon concentration of not more than 1 per cent. The gas velocity is adjusted so that carbonaceous residues are carried into a thin superposed zone 56 which may be separated from zone 54 by refractory packing or screening. The heater casing may be enlarged at this level to enhance the particle separation. Material from zone 56 is supplied to the retort through a line 55 and in larger amount to the generator, optionally after further separation of inert solids through a line 59 which may be connected to line 28. Loss of solids from zone 54 by attrition may be made up through a line 68. In a modification the heater comprises a vertical pipe containing non-combustible solid differing in density, size, and magnetic or electrical properties from the retort residues also admitted, the material being entrained in compressed air and carried to a classifier. Air may be supplied at one or more intermediate points or at the top of the pipe. Solids from an upper level of the classifier descend to the gas generator and from the base to the heater; gasification residues pass in part to the retort and in larger amount to the heater. If a highly plastic or liquid raw material is used, e.g. a mineral residual oil, the retort is supplied with a dry fluidized solid mass such as coke or fine sand on which the liquid charge is carbonized. Coal, coke, &c., may be fed direct to a generator, the retort being omitted. Or the generator may be omitted and coke from the retort burnt in the heater. Some combustion may be provided in retort or generator by admission of air, &c.