Process for the removal of H2 S and CO2 from a gas mixture

Claim 1

A process for the removal of H 2 S and CO 2 from a gaseous feed mixture and preparation of a gas with a H 2 S concentration suitable to be used in a Claus process, which process comprises: (a) countercurrently contacting said gaseous feed mixture at elevated pressure in a first absorption zone with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water, therein producing an unabsorbed portion and a first loaded absorbent solution; (b) passing said first loaded absorbent solution to a flashing zone maintained at a pressure below the total partial pressure of the CO 2 and H 2 S present in said first loaded absorbent solution at the temperature present in said flashing zone, therein effecting the liberation of a gaseous stream containing a portion of said CO 2 and H 2 S present in said first loaded absorbent solution and producing a semi-loaded absorbent solution; (c) countercurrently contacting said gaseous stream from step (b) with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water in a second absorption zone under conditions which are selective for H 2 S removal, therein producing a CO 2 -rich unabsorbed gaseous stream and a second loaded absorbent solution; (d) passing a portion of said first loaded absorbent solution to a regeneration zone, therein regenerating said first loaded absorbent and producing a lean absorbent solution; (e) passing said second loaded absorbent solution to a regeneration zone, therein regenerating said second loaded absorbent and producing a lean absorbent solution; (f) stripping at least a portion of said semi-loaded absorbent solution from step (b) with said CO 2 -rich unabsorbed gaseous stream from step (c) in a stripping zone, therein producing a stripped gaseous stream and a stripped absorbent stream; (g) passing said stripped absorbent stream to said first absorption zone at a point between where said gaseous feed mixture enters said first absorption zone and where said lean absorbent solution enters said first absorption zone; (h) concurrently contacting said stripped gaseous stream from step (f) with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water in a third absorption zone under conditions which are selective for H 2 S removal, therein producing an unabsorbed gaseous stream and a third loaded absorbent solution; and (i) passing said third loaded absorbent solution to a regeneration zone, therein regenerating said third loaded absorbent and producing a lean absorbent solution.