GB802284A - Improvements in or relating to the purification of gases - Google Patents

Abstract

802,284. Purifying gases. GAS COUNCIL. Jan. 30, 1957 [Feb. 27, 1956], No. 6058/56. Class 55 (2). A process for the simultaneous removal of hydrogen sulphide and hydrogen cyanide from fuel gas comprises washing the gas with a neutral or acidic aqueous solution of copper sulphate. Fuel gas, preferably tar- and ammonia-free, is passed upward through a washer 1 in counterflow to an aqueous solution of copper sulphate and sulphuric acid, the hydrogen sulphide content of the gas being thereby lowered from 420 to 0.03 grains per 100 cu. ft. and the hydrogen cyanide content from 80 to 3 grains per 100 cu. ft. The wash liquor passes to a filter 2 where the filter cake is washed with water and passed to a dryer 9, the clear filtrate with added water being passed by a pump 3 to the top of a scrubber 4. The filter cake, comprising sulphide and cyanogen compounds of copper is dried at 9 and crushed at 10 and the powder is passed by a pump 11 to a roaster 12 having a fluidized bed. Combustion air is supplied by a blower 13, the temperature of the bed being limited to 700‹ C. by spraying in acidic copper sulphate solution from a pump 15. The resulting copper oxide and roaster gases are cooled at 14 and contacted by a downward flow of wash liquor in the scrubber 4 which dissolves part of the copper oxide and removes the acid fog from the roaster gases. The solution passes to a stripper 5, where sulphur dioxide is removed by a counter current of air, and then to a dissolver 6 where the dissolution of the copper oxide is completed. Some regenerated acidic copper sulphate solution is passed through a pump 7, cooled and re-used in the washer 1 and some is used as a coolant in the roaster 12. The roaster gases, freed from copper compounds in the scrubber 4 are mixed with sulphur dioxide-laden air from the stripper 5 and used for making e.g. sulphuric acid.