Patent ID: 8361421

Claim:
A method of treating a raw syngas stream, to provide a treated syngas stream and an elemental sulphur stream, wherein the method comprises the steps of: (a) providing the raw syngas stream that comprises CO, H 2 , HCN, NH 3 , H 2 S, and CO 2 ; (b) passing the raw syngas stream to a hydrolysis unit to hydrolyse HCN to provide a hydrolysed syngas stream comprising CO, H 2 , H 2 S and CO 2 and a condensed water stream comprising H 2 O, NH 3 , CO 2 and H 2 S; (c) passing the hydrolysed syngas stream to an acid gas removal unit to separate H 2 S and a part of the CO 2 from the hydrolysed syngas stream to provide a treated syngas stream comprising CO 2 , CO and H 2 and an acid off-gas stream comprising H 2 S and CO 2 ; and (d) passing the acid off-gas stream and a sulphur dioxide-comprising stream comprising SO 2 to a catalytic zone to react H 2 S in the acid off-gas stream with SO 2 in the sulphur dioxide-comprising stream according to the reaction: 2H 2 S+SO 2 →3S+2H 2 O to provide an elemental sulphur stream and a catalytic zone off-gas stream comprising CO 2 and H 2 O.