GB814791A - Drying, preheating, transferring and carbonizing coal - Google Patents

Abstract

814,791. Preheating furnace charges ; coking coal; material for making coke. ALLIED CHEMICAL CORPORATION, [formerly ALLIED CHEMICAL & DYE CORPORATION]. July 24, 1957 [Sept. 10, 1956], No. 23446/57. Classes 51 (1), 51(2), 55 (1) and 55 (2). [Also in Group XIII] A compact column 12 of wet coal, deep enough to prevent escape of hot gases from the top charging opening of a dryer and preheater, is supported on a grate 15 arranged to allow free upward passage of hot gases and mechanically operated to allow controlled amounts of coal to fall into a fluidized bed 13 supported on a grate 21 which is mechanically operated to allow dry coal to fall through it. Hot gases enter below the grate 21 through an inlet 20 at a sufficient velocity to maintain the fluidized bed 13, and after passing through the bed 13 give up entrained particles of coal in the column 12 before passing to an annular passage 16 surrounding the coal 12. Water sprays 37 wash the gases and inner walls 33 in the passage 16, and a trough 34 collects the drainage. The annular passage 16 is formed by a sleeve 33 within the rectangular casing of the dryer, and the column of coal may be divided by spaced parallel walls 35 forming an intermediate passage closed at the top. The gates 15, 21 each comprise a number of parallel rotating shafts, with adjacent shafts rotating in opposite directions and reversing at intervals to allow coal to fall through. The triangular section shafts, Fig. 2, may be replaced by shafts carrying plates, Fig. 5 (not shown). Coal from the storage bin 1 of a coke oven battery drops into a larry car 3, running on rails 5, and is dumped into a bin 6 feeding a belt conveyer 7. A vertical conveyer 8 and a second belt conveyer 9 carry it to a plough-type tripper which pushes the coal into the top of the preheater. The dry, preheated coal may drop into the larry car 3 and be fed direct into the coke ovens, or it may pass through a screw feeder, Fig. 8 (not shown), or a star feeder, Fig. 10 (not shown), to a coal charging pipe along which it is pneumatically conveyed by coal gas which escapes from the ovens with the gases produced by the coking process. To prevent coking, the inlet part of each coke oven 74, Fig. 9, which is sealed by a member 81, has cooling steam introduced through a pipe 82 prior to charging. To prevent fires starting when the ovens are charged with dry, preheated coal, between 0.5 and 5 per cent of residual fuel oil or hydrocarbon pitch of a melting point between 120‹ and 240‹ C. or a mixture of both is added to the dry coal. A blend of low-volatile and highvolatile coking coals containing 25-36 per cent of volatile matter with a smaller amount of antifracturant containing 20-100 per cent more antifracturant than normally used when coking wet coal can be used, and carbonized at a flue temperature of 1650-1950‹ F. The hot combustion gases used to dry the coal flow upwardly through the fluidized bed at a velocity of 4-10 feet per second, the temperature of the preheated coal being between 600-700‹ F. Specifications 465,378 and 625,876 are referred to.