Patent ID: 8431101

Claim:
A method of treating an acid gas stream comprising H 2 S and CO 2 to provide an aqueous ammonium sulphate stream, wherein the method comprises at least the steps of: (a) passing the acid gas stream to an incinerator to oxidise H 2 S to SO 2 and to provide an incinerator flue gas stream comprising SO 2 and CO 2 ; (b) passing the incinerator flue gas stream to a sulphuric acid unit to produce H 2 SO 4 from SO 2 in the flue gas stream and to provide an aqueous sulphuric acid stream and a sulphuric acid unit off-gas stream comprising CO 2 ; and (c) passing at least a part of the aqueous sulphuric acid stream to an ammonia scrubber which is provided with a first off-gas stream which comprises NH 3 , H 2 S and CO 2 to separate NH 3 to provide a scrubber off-gas stream comprising H 2 S and CO 2 and an aqueous ammonium sulphate stream.