Patent GB-427849-A (GB)
Title: Improvements in or relating to the carbonization of coal
IPC: C10B57/08
Filed: 1934-06-28
Abstract: 427,849. Carbonizing processes ; materials for making coke. PITTSBURGH COAL CARBONIZATION CO., 1130, Oliver Building, Pittsburg, U.S.A.-(Assignees of Lesher, C. E.) June 28, 1934, No. 19115. Convention date, July 20, 1933. [Classes 55 (i) and 55 (ii)] In a process of carbonizing coal, the charge is roasted in the presence of air to restrict its agglutinating properties, and a storage body of roasted coal maintained, a regulated amount being continually withdrawn from this body and subjected to carbonizing treatment. By this means slight variations in the amount of feed, or in the character of the coal, or in the conditions in the roaster have no appreciable effect upon the comparatively large amount of the storage body of coal. The temperature and composition of this storage body is maintained by keeping it in a stream which is constantly recirculated through the roaster, so that, in subsequent heating in a rotary retort, coal balls of a desired size and density are formed. Coal balls may also be obtained by adding to the roasted coal prior to its carbonization a regulated amount of raw coal partially roasted coal, or coke to adjust its agglutinating properties. A temperature of 400 to 850‹ F. is maintained during the roasting stage before low temperature carbonization takes place, in a manner similar to that described in Specifications 217,554 and 275,602, [both in Class 55 (i)]. Suitable apparatus comprises a roaster 1 and rotary carbonizing drum 2, the coal being crushed to pass a one-eighth inch mesh screen and mixed if desired with coke dust. The charge from a hopper 3 is fed on to a rotary distributer 4 from which an adjustable flow 5 diverts a regulated amount into a shoot 6 delivering through an opening 7 into the roaster. Decks 9-14 in the roaster are heated by flues 15, are provided with spaced air inlets 26, and their surfaces are traversed by blades 23 on endless chains 20 carried by sprockets 21. The coal from deck 9 is fed on to a deflector 28 which directs it on to the deck 10, similar deflectors being provided at each deck, the charge from deck 14 falling into a hopper 33. The deflectors are formed in sections and are rotatable so that coal from any deck may be discharged directly to the hopper 33, and by this means partial roasting may be effected, or the partially roasted charge from an upper deck may be mixed with the completely roasted charge from the lowermost deck. The treated coal is raised by an elevator 47, and discharged into a shoot 48, and redelivered to the roaster. A portion of the coal stream is tapped off and fed through a measuring star wheel and conveyers 54, 55 to the rotary carbonizing drum 2. The coal is semi-coked, and formed into coal balls which are discharged through a shoot 59. The distillates are withdrawn through a conduit 61. The heating gases for the carbonizer enter through a flue 71 into a heating jacket, and are discharged into a flue 72 leading to the roaster, from which they are recirculated to the furnace 70 supplying the carbonizer 2. If coal in the roaster is overoxidized, raw coal may be diverted by a flow 80 from the rotary plate 4 into a shoot 81 delivering into the hopper 33. If the coal is insufficiently roasted, coke breeze may be supplied by a belt conveyer 82 to a heater 83 subjected to the heat from the gases passing from the carbonizer 2 to the roaster 1. This breeze is fed by an elevator 84 to a conduit 85, and screw conveyer 86, leading to conveyers 54 and 55 and the carbonizer. In a modification, Fig. 10, the roasted coal falls to the floor 140 of the roaster and is kept in circulation by a bucket conveyer 130, a portion of the roasted charge being withdrawn through a conduit 134 in the deck 131 leading to the carbonizer. Raw coal is supplied from hopper 120, or coke from feed screw 152 to the coal going to the carbonizer.