GB597598A - Gas purification process - Google Patents

Abstract

<PICT:0597598/III/1> In a process for the recovery of hydrogen sulphide from coke oven gas by scrubbing the gas with an aqueous alkaline liquor which absorbs the hydrogen sulphide the fouled scrubbing liquor is regenerated by heating it at sub-atmospheric pressure with steam formed by the indirect contact of regenerated scrubbing liquor with hot coke oven gas after the latter flows from the collecting mains of a coke oven battery. As shown, coke-oven gas is scrubbed in tower 4, passing in through pipe 2 and out through pipe 6, the scrubbing liquid, for example a sodium carbonate solution, being sprayed through nozzles 74. The fouled liquor from the bottom of the column passes to tank 10 into which fresh solution made up in tank 14 is also pumped. The mixed liquids are pumped through line 24 and sprayed through nozzles 28 in the top of regeneration tower 26, up which steam is passing. Uncondensed steam and hydrogen sulphide leave the top of tower 26 through pipe 30, and pass through condensers 32 and 36, the hydrogen sulphide being extracted by pump 40 which maintains a subatmospheric pressure in the regeneration system, and the condensed steam passing to tank 80 whence it is pumped into the base of tower 4 for recirculation. A part of the regenerated absorbant from the bottom of tower 26 is pumped by pump 62 to a cooler 66 and thence to nozzle 74. The remainder of the solution is pumped by pump 46 into indirect heating contact with gas direct from the coke-oven battery, the contact taking place through coils 50 in heat exchanger 52 which acts as a primary cooler for the coke-oven gas. The temperature of the solution may be raised 10 DEG C and when it passes through pipe 59 into the base of tower 26, is partially vaporised supplying steam to strip the fouled absorbant passing down the tower from nozzles 28. A reboiler 27 may also supply heat at the base of the tower. Both towers 26 and 4 contain packing.