Sulfur recovery process using metal oxide absorbent with regenerator recycle to Claus catalytic reactor

Claim 2

Apparatus comprising: a Claus plant for converting H 2 S in an acid gas feedstream thereto to elemental sulfur by the Claus reaction and for producing a Claus plant tailgas, the Claus plant comprising a Claus furnace and a Claus catalytic reactor; absorption means for receiving the Claus plant tailgas and for removing both H 2 S and SO 2 in the presence of ZnO, the step of removing SO 2 optionally comprising converting SO 2 to H 2 S and removing such H 2 S, producing ZnS and absorber effluent; regeneration means for regenerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; oxidation means distinct from the Claus furnace for removing O 2 by oxidizing H 2 S to SO 2 in the presence of O 2 ; first conduit means for providing a withdrawn portion of the acid gas feedstream to the Claus plant to the catalytic oxidation means; second conduit means for providing regenerator effluent from the regeneration means to the catalytic oxidation means; and third conduit means for providing effluent from the catalytic oxidation means to the Claus catalytic reactor of the Claus plant.

Claim 3

The apparatus of claim 1 wherein: the oxidation means comprises a catalytic oxidation means comprising a catalyst effective for removing O 2 by oxidizing H 2 S to SO 2 in the presence of O 2 .

Claim 4

The Apparatus of claim 1 wherein: the Claus catalytic reactor is a Claus catalytic reactor operated above the sulfur dew point wherein elemental sulfur formed by the Claus reaction is continuously removed in the vapor phase and recovered in a sulfur condenser.

Claim 5

The Apparatus of claim 1 wherein: The Claus catalytic reactor is a Claus catalytic adsorptive reactor in which a preponderance of elemental sulfur formed by the Claus reaction is deposited on Claus catalyst and later recovered therefrom.

Claim 6

The Apparatus of claim 1 further comprising fourth conduit means for providing absorber effluent from the absorption means to the regeneration means, the fourth conduit means comprising a heater for heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 , and catalytic means for oxidizing reducing species comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.

Claim 7

The Apparatus of claim 1 wherein the Claus catalytic reactor to which effluent from the oxidation means is provided is a Claus catalytic adsorptive reactor in which a preponderance of elemental sulfur formed by the Claus reaction is deposited on Claus catalyst and later recovered therefrom; and wherein the Claus plant comprises a Claus catalytic reactor operated above the sulfur dewpoint upstream of said Claus catalytic adsorptive reactor.

Claim 8

The Apparatus of claim 1 further comprising: regeneration feed means for introducing an O 2 containing gas into the regeneration means for regenerating ZnS to ZnO; and wherein the first conduit means is effective for providing a withdrawn portion of the acid gas feedstream to the Claus plant to the oxidation means in amounts in excess of those required for the stoichiometric removal of O 2 by combustion with H 2 S.

Claim 9

Method comprising: converting H 2 S in an acid gas feedstream to a Claus plant to elemental sulfur by the Claus reaction and producing a Claus plant tailgas in a Claus plant comprising a Claus furnace and a Claus catalytic reactor; removing both H 2 S and SO 2 in the presence of ZnO, optionally after converting SO 2 to H 2 S, producing ZnS and absorber effluent; regenerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; providing a portion of acid gas feedstream withdrawn upstream of the Claus furnace to oxidation means distinct from the Claus furnace for oxidizing H 2 S to SO 2 in the presence of O 2 ; further providing regenerator effluent to the oxidation means; and providing effluent from the oxidation means to the Claus catalytic reactor of the Claus plant.

Claim 10

Method comprising: converting H 2 S in an acid gas feedstream to a Claus plant to elemental sulfur by the Claus reaction and producing a Claus plant tailgas in a Claus plant comprising a Claus furnace and a Claus catalytic reactor; removing both H 2 S and SO 2 in the presence of ZnO, optionally after converting SO 2 to H 2 S, producing ZnS and absorber effluent; regenerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; providing a portion of acid gas feedstream withdrawn upstream of the Claus furnace to oxidation means distinct from the Claus furnace for oxidizing H 2 S to SO 2 in the presence of O 2 ; further providing regenerator effluent to the oxidation means; and providing effluent from the oxidation means to the Claus catalytic reactor of the Claus plant.

Claim 11

The Method of claim 8 wherein: the oxidation means comprises catalytic oxidation means comprising an effective catalyst for oxidizing H 2 S to SO 2 in the presence of O 2 .

Claim 12

The Method of claim 8 wherein: the Claus catalytic reactor is a Claus catalytic reactor operated above the sulfur dew point wherein elemental sulfur formed by the Claus reaction is continuously removed in the vapor phase and recovered in a sulfur condenser.

Claim 13

The Method of claim 8 wherein: the Claus catalytic reactor is a Claus catalytic adsorptive reactor in which a preponderance of elemental sulfur formed by the Claus reaction is deposited on Claus catalyst and recovered therefrom.

Claim 14

The Method of claim 8 comprising: providing absorber effluent as a diluent for regeneration by steps comprising heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 and oxidizing reducing species in the absorber effluent comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.

Claim 15

Apparatus comprising: a Claus plant for converting H 2 S in an acid gas feedstream thereto to elemental sulfur by the Claus reaction and for producing a Claus plant tailgas, the Claus plant comprising a Claus furnace and a Claus catalytic reactor; absorption means for receiving the Claus plant tailgas and for removing both H 2 S and SO 2 in the presence of ZnO, the step of removing SO 2 optionally comprising converting SO 2 to H 2 S and removing such H 2 S, producing ZnS and absorber effluent; regneration means for regenerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; oxidation means for removing O 2 by oxidizing H 2 S to SO 2 in the presence of O 2 ; first conduit means for providing a withdrawn portion of the acid gas feedstream to the Claus plant to the catalytic oxidation means; second conduit means for providing regenerator effluent from the regeneration means to the catalytic oxidation means; third conduit means for providing effluent from the catalytic oxidation means to the Claus catalytic reactor of the Claus plant; and fourth conduit means for providing absorber effluent from the absorption means to the regeneration means, the fourth conduit means comprising a heater for heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 , and catalytic means for oxidizing reducing species comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.

Claim 16

Apparatus comprising: a Claus plant for converting H 2 S in an acid gas feedstream thereto to elemental sulfur by the Claus reaction and for producing a Claus plant tailgas, the Claus plant comprising a Claus furnace and a Claus catalytic reactor; absorption means for receiving the Claus plant tailgas and for removing both H 2 S and SO 2 in the presence of ZnO, the step of removing SO 2 optionally comprising converting SO 2 to H 2 S and removing such H 2 S, producing ZnS and absorber effluent; regneration means for regenerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; oxidation means for removing O 2 by oxidizing H 2 S to SO 2 in the presence of O 2 ; first conduit means for providing a withdrawn portion of the acid gas feedstream to the Claus plant to the catalytic oxidation means; second conduit means for providing regenerator effluent from the regeneration means to the catalytic oxidation means; third conduit means for providing effluent from the catalytic oxidation means to the Claus catalytic reactor of the Claus plant; and fourth conduit means for providing absorber effluent from the absorption means to the regeneration means, the fourth conduit means comprising a heater for heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 , and catalytic means for oxidizing reducing species comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.

Claim 17

Method comprising: converting H 2 S in an acid gas feedstream to a Claus plant to elemental sulfur by the Claus reaction and producing a Claus plant tailgas in a Claus plant comprising a Claus furnace and a Claus catalytic reactor; removing both H 2 S and SO 2 in the presence of ZnO, the step of removing SO 2 optionally comprising converting SO 2 and removing such H 2 S, producing ZnS and absorber effluent; regerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; providing a portion of acid gas feedstream withdrawn upstream of the Claus furnace to oxidation means for oxidizing H 2 S to SO 2 in the presence of O 2 ; further providing regenerator effluent to the oxidation means; providing effluent from the oxidation means to the Claus catalytic reactor of the Claus plant; and providing absorber effluent as a diluent for regeneration by steps comprising heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 and oxidizing reducing species in the absorber effluent comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.

Claim 18

Method comprising: converting H 2 S in an acid gas feedstream to a Claus plant to elemental sulfur by the Claus reaction and producing a Claus plant tailgas in a Claus plant comprising a Claus furnace and a Claus catalytic reactor; removing both H 2 S and SO 2 in the presence of ZnO, the step of removing SO 2 optionally comprising converting SO 2 and removing such H 2 S, producing ZnS and absorber effluent; regerating ZnS to ZnO in the presence of O 2 producing regenerator effluent; providing a portion of acid gas feedstream withdrawn upstream of the Claus furnace to oxidation means for oxidizing H 2 S to SO 2 in the presence of O 2 ; further providing regenerator effluent to the oxidation means; providing effluent from the oxidation means to the Claus catalytic reactor of the Claus plant; and providing absorber effluent as a diluent for regeneration by steps comprising heating absorber effluent and O 2 to a temperature effective for regenerating ZnS to ZnO in the presence of O 2 and oxidizing reducing species in the absorber effluent comprising H 2 and optionally CO in the presence of O 2 and an effective oxidation catalyst.