Removal of Sulphuretted hydrogen from Coal gas

Abstract

Of the sulphur containing gases that are present commercial coal gas, sulphuretted hydrogen amounts to 90 to 95%. These sulphur containing gases are produced from sulphur which is present in all types of coal used. The presence of sulphuretted hydrogen and other sulphur compounds in gas objectionable for various reason. Sulphuretted hydrogen causes drip water to be corrosive and it is also corrosive to metal devices in smaller gas-meters and other equipments for handling gas. It causes internal corrosion in gas atmosphere as in meters and regulators and special appliances. Sulphur compounds in coal gas utilised for certain other purpose is also objectionable. In gas heated ovens for annealing glass the formation of deposits of "bloom" on the glass-ware had been blamed on small amounts in the gas. In certain heat treatment processes of steel and other metals and alloys evens 7 to 10 grains of organic sulphur per 100 cubic feet cause great difficulties. For heating open-hearth furnaces and other furnaces for handling steels excessive sulphur contents are undesirable. The presences of sulphur compounds in gases undesirable also in "bright annealing" of wires and similar products. There are numerous industrials uses of coal gas in which gases of low sulphur contents are quite essential. When discharged into atmosphere, it causes considerable damages to vegetables life, industrial plants and household equipments. The early processes of removing sulphur compounds from gas were entirely for the purpose of eliminating the odour in the products of combustion. Little thought was given to the sulphur itself. The sulphur containing waste materials was later found to have great industrial value. In recent years extensive work has been done on different methods for removing and utilising the hydrogen sulphide and sulphur compounds as the price level of sulphur is sufficiently high and sometimes the waste disposal is sufficiently expensive. Indian coal usually contains 0.3 to 1.0 % sulphur. Assam and Punjab coal of course contain high amount of ranging from 2.0 to10.0%2. Very few coke oven industry in India adopt the recovery of sulphur from coke oven gas. However may be the small percentage of sulphur in Indian coal there is sufficient scientific and economical background for the Indian industries to adopt means for the utilisation of the hydrogen sulphide from the coke oven gas, for India has to depend solely upon other countries for sulphur.