GB271805A - Process and installation for eliminating sulphuretted hydrogen from gases - Google Patents

Abstract

271,805. Still, C. May 25, 1926, [Convention date]. Materials for purifying gas.-In removing sulphuretted hydrogen from gas by washing with an aqueous suspension containing ferrous and ferric hydroxides or carbonates, which is regenerated by treating with air, the circulating suspension never contains more than 2 per cent of iron. The wash liquor may be rendered alkaline by means of ammonia solution or a solution of sodium hydrate or carbonate, or by means of the ammonia present in the gas being treated. The sulphided liquor flows from the scrubber 2 to a tank 6 and is pumped into the bottom of a regenerating tower 10 provided with an air supply pipe 11. A foaming mass containing regenerated ferric hydroxide or carbonate together with sulphur passes off from the top of the tower through a pipe 12 to a receptacle 13 in which the sulphur is to a large extent separated as a foam from the suspension which is returned to the spray 4. The foam which consists of sulphur with a small amount of iron floats off to a receptacle 16 and after draining, passes to a centrifuge. 19. The small amount of iron withdrawn from the system with the sulphur is replaced by adding a ferrous or ferric salt solution which is made up in a vessel 25 and passed to the tank 6. When neutral washing liquor is used, alkali is added to precipitate the iron as hydrate or carbonate. With repeated circulation a concentrated solution of thiosulphate is formed and when this is withdrawn from the plant, a correspondinging amount of alkali must be introduced unless the gas being purified contains ammonia.