Process of improved sulfur capture from a syngas mixture

Patent metadata

Field	Value
Publication number	US-2020360855-A1
Application number	US-202016877425-A
Country	US
Kind code	A1
Filing date	May 18, 2020
Priority date	May 17, 2019
Publication date	Nov 19, 2020
Grant date	—

Abstract

A process for sweetening a syngas stream, the process comprising the steps of: providing a syngas stream to a nonselective amine absorption unit, the sour syngas stream comprising syngas, carbon dioxide, and hydrogen sulfide; separating the syngas stream in the nonselective amine absorption unit to obtain an overhead syngas stream and an acid gas stream; introducing the acid gas stream to a membrane separation unit, the acid gas stream comprising hydrogen sulfide and carbon dioxide; separating the acid gas stream in the membrane separation unit to produce a retentate stream and a permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide; introducing the retentate stream to a sulfur recovery unit; processing the retentate stream in the sulfur recovery unit to produce a sulfur stream and a tail gas stream, wherein the sulfur stream comprises liquid sulfur.

First claim

We claim:

1 . A process for sweetening a syngas stream, the process comprising the steps of:
supplying a syngas stream to a nonselective absorption unit, the syngas stream comprising syngas, carbon dioxide, and hydrogen sulfide; separating the syngas stream in the nonselective absorption unit to obtain an overhead syngas stream and an acid gas stream; introducing the acid gas stream to a membrane separation unit, the acid gas stream comprising hydrogen sulfide and carbon dioxide; separating the acid gas stream in the membrane separation unit to produce a retentate stream and a permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide; introducing the retentate stream to a sulfur recovery unit;

2 . The process of claim 1 , wherein a concentration of hydrogen sulfide in the retentate stream is between 50 mol % and 95 mol %.

3 . The process of claim 2 , wherein the concentration of hydrogen sulfide in the retentate stream is greater than 90 mol %.

4 . The process of claim 1 , wherein a concentration of hydrogen sulfide in the permeate stream is between 0.01 mol % and 0.1 mol %.

5 . The process of claim 1 , further comprising the step of:
discharging the permeate stream to the atmosphere without subjecting the permeate stream to any additional hydrogen sulfide separation.

6 . The process of claim 1 , wherein a concentration of hydrogen sulfide in the overhead syngas stream is between 1 ppm and 1,000 ppm.

7 . The process of claim 1 , wherein a concentration of carbon dioxide in the overhead syngas stream is between 1 mol % and 3 mol %.

8 . The process of claim 1 , wherein the membrane separation unit comprises a membrane, wherein the membrane is a carbon dioxide-selective membrane.

9 . The process of claim 8 , wherein the membrane has carbon dioxide-hydrogen sulfide selectivity of at least 5.

10 . The process of claim 8 , wherein the membrane has carbon dioxide-hydrogen sulfide selectivity of at least 10.

11 . The process of claim 8 , wherein the membrane has carbon dioxide-hydrogen sulfide selectivity of at least 20.

12 . The process of claim 8 , wherein the membrane has carbon dioxide-hydrogen sulfide selectivity of at least 30 .

13 . The process of claim 8 , wherein the membrane comprises a perfluorinated polymer.

14 . The process of claim 1 , wherein the membrane separation unit comprises a first membrane separation stage and a second membrane separation stage with the first and second membrane separation stages arranged in a retentate-in-series configuration.

15 . The process of claim 1 , wherein the membrane separation unit comprises a first membrane separation stage and a second membrane separation stage with the first and second membrane separation stages arranged in a permeate-in-series configuration.

16 . The process of claim 1 , further comprising the steps of:
supplying the permeate stream to a selective amine absorption unit and treating the permeate stream using an amine absorption process to obtain an overhead carbon dioxide stream and a recovered hydrogen sulfide stream.

17 . The process of claim 16 , further comprising the step of:
discharging the overhead carbon dioxide stream to the atmosphere without subjecting the overhead carbon dioxide stream to any additional hydrogen sulfide separation.

18 . A process for recovering sulfur and carbon dioxide from a syngas stream, the process comprising the steps of:
supplying a syngas stream to a nonselective absorption unit, the syngas stream comprising syngas, carbon dioxide, and hydrogen sulfide; separating the syngas stream in the nonselective absorption unit using an absorption process to produce an overhead syngas stream and an acid gas stream; introducing the acid gas stream to a selective absorption unit; processing the acid gas stream in the selective absorption unit to obtain an overhead carbon dioxide stream and a recovered hydrogen sulfide stream; introducing the recovered hydrogen sulfide stream to a membrane separation unit, the recovered hydrogen sulfide stream comprising hydrogen sulfide and carbon dioxide; separating the recovered hydrogen sulfide stream in the membrane separation stage to produce a retentate stream and a permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide;

19 . introducing the retentate stream to a sulfur recovery unit; The process of claim 18 , wherein a concentration of hydrogen sulfide in the retentate stream is between 50 mol % and 95 mol %.

20 . The process of claim 18 , wherein a concentration of hydrogen sulfide in the overhead carbon dioxide stream is between 0.01 mol % and 0.1 mol %.

21 . The process of claim 18 , further comprising the step of discharging the overhead carbon dioxide stream to the atmosphere without subjecting the overhead carbon dioxide stream to any additional hydrogen sulfide separation.

22 . The process of claim 18 , wherein the membrane separation unit comprises a membrane, wherein the membrane is a carbon dioxide-selective membrane.

23 . The process of claim 22 , wherein the membrane has carbon dioxide-hydrogen sulfide selectivity of at least 5.

24 . The process of claim 18 , wherein the membrane separation unit comprises a first membrane separation stage and a second membrane separation stage with the first and second membrane separation stages arranged in a retentate-in-series configuration.

25 . The process of claim 18 , wherein the membrane separation unit comprises a first membrane separation stage and a second membrane separation stage with the first and second membrane separation stages arranged in a permeate-in-series configuration.

Assignees

• Saudi Arabian Oil Co
• Membrane Tech And Research Inc

Inventors

• Vaidya Milind M
• Duval Sebastien A
• Hamad Feras
• Baker Richard
• Merkel Tim
• Lokhandwala Kaeeid
• Huang Ivy
• Bahamdan Ahmad A
• Al-Otaibi Faisal D

Classifications

• B01D2258/02

  Other waste gases · CPC title

• B01D2257/304

  Hydrogen sulfide · CPC title

• B01D2256/24

  Hydrocarbons · CPC title

• B01D53/228

  characterised by specific membranes · CPC title

• B01D53/1468 Primary

  Removing hydrogen sulfide · CPC title