Enhancement of claus tail gas treatment with membrane and reducing step

Patent metadata

Field	Value
Publication number	US-9943802-B1
Application number	US-201715457338-A
Country	US
Kind code	B1
Filing date	Mar 13, 2017
Priority date	Mar 13, 2017
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A method for removing sulfur-containing compounds from a sulfur recovery unit (SRU) tail gas stream includes the steps of introducing the SRU tail gas stream to a reducing unit to produce a membrane feed, the reducing unit configured to reduce the sulfur-containing compounds to hydrogen sulfide, introducing the membrane feed to a hydrogen sulfide membrane unit, the hydrogen sulfide membrane unit comprising a membrane, wherein the membrane feed comprises hydrogen sulfide, allowing the membrane feed to contact a feed side of the membrane such that hydrogen sulfide permeates through the membrane to a permeate side, and collecting the retentate gases that fail to permeate through the membrane to produce a stack feed, wherein the stack feed comprises retentate gases.

First claim

What is claimed is:

1. A method for removing sulfur-containing compounds from a sulfur recovery unit (SRU) tail gas stream, the method comprising the steps of:
introducing the SRU tail gas stream to a reducing unit to produce a membrane feed, the reducing unit configured to reduce the sulfur-containing compounds to hydrogen sulfide;
introducing the membrane feed to a hydrogen sulfide membrane unit, the hydrogen sulfide membrane unit comprising a membrane, wherein the membrane feed comprises hydrogen sulfide;
allowing the membrane feed to contact a feed side of the membrane such that hydrogen sulfide permeates through the membrane to a permeate side; and
collecting the retentate gases that fail to permeate through the membrane to produce a stack feed, wherein the stack feed comprises retentate gases.

2. The method of claim 1 , wherein the membrane is selected from the group consisting of a hydrogen sulfide-selective membrane and an acid gas-selective membrane.

3. The method of claim 1 wherein the step of introducing the SRU tail gas stream to a reducing unit to produce a membrane feed, further comprises the steps of:
introducing the SRU tail gas stream to a reduction reactor of the reducing unit;
introducing a reducing agent to the reduction reactor;
allowing the sulfur-containing compounds to react with the reducing agent in reduction reactions to produce a reduced stream, wherein the reduction reactions reduce the sulfur-containing compounds to hydrogen sulfide, wherein the reduced stream comprises non-condensing gases and water vapor;
introducing the reduced stream to a reduction separator; and
separating the non-condensing gases from the water vapor in the reduction separator to produce the membrane feed and a waste water stream, wherein the membrane feed comprises the non-condensed gases, wherein the non-condensed gases comprise hydrogen sulfide, and wherein the waste water stream comprises condensed water.

4. The method of claim 1 further comprising the step of:
supplying a sweep air feed to the permeate side of the membrane;
collecting the hydrogen sulfide that permeates the membrane in the sweep air feed to produce a hydrogen sulfide enriched air; and
introducing the hydrogen sulfide enriched air to a sulfur recovery unit, the sulfur recovery unit configured to produce the SRU tail stream.

5. The method of claim 4 further comprising the steps of:
introducing an acid gas feed to an enrichment unit, wherein the acid gas feed comprises hydrogen sulfide and carbon dioxide;
allowing the hydrogen sulfide to separate from the carbon dioxide to produce an enriched feed and a carbon dioxide rich stream, wherein the enriched feed comprises hydrogen sulfide, wherein the carbon dioxide rich stream comprises carbon dioxide; and
introducing the enriched feed to the sulfur recovery unit.

6. The method of claim 5 further comprising the steps of:
introducing an acid gas feed to an enrichment unit, wherein the acid gas feed comprises hydrogen sulfide and carbon dioxide;
introducing a membrane recycle to the enrichment unit, wherein the membrane recycle comprises hydrogen sulfide and carbon dioxide;
allowing the hydrogen sulfide to separate from the carbon dioxide in the enrichment unit to produce an enriched feed and a carbon dioxide rich stream, wherein the enriched feed comprises hydrogen sulfide, wherein the carbon dioxide rich stream comprises carbon dioxide;
supplying the carbon dioxide rich stream to the permeate side of the membrane of hydrogen sulfide membrane unit;
collecting the hydrogen sulfide that permeates through the membrane to the permeate side in the carbon dioxide rich stream to produce the membrane recycle; and
introducing the enriched feed to a sulfur recovery unit, the sulfur recovery unit configured to produce the SRU tail gas stream.

7. The method of claim 1 further comprising the steps of:
forming a hydrogen sulfide recycle stream from the hydrogen sulfide that permeates the membrane of the hydrogen sulfide membrane unit, wherein the hydrogen sulfide recycle stream comprises hydrogen sulfide.

8. The method of claim 7 further comprising the steps of:
mixing the hydrogen sulfide recycle stream with an air feed to form a diluted recycle stream, where the diluted recycle stream comprises hydrogen sulfide and air; and
introducing the diluted recycle stream to a sulfur recovery unit, the sulfur recovery unit configured to produce the SRU tail gas stream.

9. The method of claim 7 further comprising the steps of:
introducing the hydrogen sulfide recycle stream to an enrichment unit;
introducing an acid gas feed to the enrichment unit, wherein the acid gas feed comprises hydrogen sulfide and carbon dioxide;
allowing the hydrogen sulfide to separate from the carbon dioxide in the enrichment unit to produce an enriched feed and a carbon dioxide rich stream, wherein the enriched feed comprises hydrogen sulfide, wherein the carbon dioxide rich stream comprises carbon dioxide; and
introducing the enriched feed to a sulfur recovery unit, the sulfur recovery unit configured to produce the SRU tail gas stream.

10. The method of claim 7 further comprising the steps of:
mixing the hydrogen sulfide recycle stream with an acid gas feed to produce a mixed feed, wherein the mixed feed comprises hydrogen sulfide and carbon dioxide; and
introducing the mixed feed to an enrichment unit; and
allowing the hydrogen sulfide to separate from the carbon dioxide in the enrichment unit to produce an enriched feed and a carbon dioxide rich stream, wherein the enriched feed comprises hydrogen sulfide, wherein the carbon dioxide rich stream comprises carbon dioxide.

11. The method of claim 7 further comprising the steps of:
introducing an acid gas feed to an enrichment unit, where the acid gas feed comprises hydrogen sulfide and carbon dioxide;
allowing the hydrogen sulfide to separate from the carbon dioxide in the enrichment unit to produce an enriched feed and carbon dioxide rich stream, where the enriched feed comprises hydrogen sulfide, where the carbon dioxide rich stream comprises carbon dioxide;
mixing the hydrogen sulfide recycle stream with the enriched feed to produce a mixed enriched feed; and
introducing the mixed enriched feed to a sulfur recovery unit, the sulfur recovery unit configured to produce the SRU tail gas stream.

12. The method of claim 7 , further comprising the steps of:
introducing an acid gas feed to a carbon dioxide membrane unit, the carbon dioxide membrane unit comprising a carbon dioxide-selective membrane, where the acid gas feed comprises carbon dioxide and hydrogen sulfide;
allowing the acid gas feed to contact a feed side of the carbon dioxide-selective membrane such that carbon dioxide permeates through the carbon dioxide-selective membrane to a permeate side;
collecting the carbon dioxide that permeates the carbon dioxide-selective membrane to form a carbon dioxide permeate, where the carbon dioxide permeate comprises carbon dioxide and hydrogen sulfide;
collecting feed gases that fail to permeate the carbon dioxide-selective membrane to form a hydrogen sulfide retentate, where the hydrogen sulfide retentate comprises hydrogen sulfide;
introducing the carbon dioxide permeate to an enrichment unit;
allowing the hydrogen sulfide to separate from the carbon dioxide in the enrichment unit to produce an enriched feed and carbon dioxide rich stream, where the enriched feed comprises hydrogen sulfide, where the carbon dioxide rich stream comprises carbon dioxide;
mixing the hydrogen sulfide recycle stream, the enriched feed and the hydrogen sulfide retentate to produce a hydrogen sulfide rich feed;

Assignees

• Saudi Arabian Oil Co

Inventors

• Ballaguet Jean-Pierre R
• Vaidya Milind M
• Hamad Feras
• Duval Sebastien A
• Charry-Prada Iran D

Classifications

• B01D53/22

  by diffusion (manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00) · CPC title

• C01B17/164

  Preparation by reduction of oxidic sulfur compounds · CPC title

• B01D2257/504

  Carbon dioxide · CPC title

• B01D53/265

  by refrigeration (condensation) · CPC title

• B01D53/226 Primary

  in serial connexion · CPC title