Patent ID: 8765086

Claim:
A process for removal of H 2 S and CO 2 from an acid gas stream comprising H 2 S and CO 2 , wherein the process comprises the steps of: (a) reacting H 2 S in the acid gas stream with SO 2 to form sulphur vapour and water vapour, thereby obtaining a first off-gas stream comprising CO 2 , water vapour, sulphur vapour, residual SO 2 and residual H 2 S; (b) converting residual SO 2 in the first off-gas stream to H 2 S in a first off-gas treating reactor, thereby obtaining a second off-gas stream depleted in SO 2 and enriched in H 2 S and CO 2 compared to the first off-gas stream; (c) contacting the second off-gas stream with an H 2 S absorbing liquid, thereby transferring H 2 S from the gas stream to the H 2 S absorbing liquid to obtain an H 2 S absorbing liquid enriched in H 2 S and a third off-gas stream enriched in CO 2 ; and (d) removing CO 2 from the third off-gas stream by contacting the third off-gas stream with a CO 2 absorbing liquid in a CO 2 absorber at an operating pressure in the range 20 to 200 mbarg, thereby transferring CO 2 from the third off-gas stream to the CO 2 absorbing liquid to obtain a CO 2 absorbing liquid enriched in CO 2 and a purified gas stream comprising less than 0.5 vol % of CO 2 .