Process for recovering helium from a multi-component gas stream

• US 4,717,407 A
• Filed: 06/16/1986
• Issued: 01/05/1988
• Est. Priority Date: 12/21/1984
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Agrawal, Rakesh, Auvil, Steven R., Choe, Jung S.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US06/874,745
• Time in Patent Office: 568 Days
• Field of Search: 62/17, 62/18, 62/20, 55/68, 55/158, 210/500.21
• US Class Current: 62/624
• CPC Class Codes: B01D 53/229 Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• CPC Class Codes: C01B 2210/001 by making use of membranes
• CPC Class Codes: C01B 2210/0014 by adsorption in solids
• CPC Class Codes: C01B 2210/0025 by absorption in liquids
• CPC Class Codes: C01B 2210/0031 Helium
• CPC Class Codes: C01B 23/0094 Combined chemical and physical processing
• CPC Class Codes: F25J 2205/40 using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• CPC Class Codes: F25J 2205/80 using membrane, i.e. including a permeation step
• CPC Class Codes: F25J 2245/02 Recycle of a stream in general, e.g. a by-pass stream
• CPC Class Codes: F25J 3/029 of helium

Abstract

The present invention involves an efficient process for recovering helium from a gas mixture containing helium and at least one other component. Separation is effected by integrating a semi-permeable membrane-based unit with a non-membrane type separation unit.

Claims

1. A process for recovering helium from a feed gas mixture comprising helium and at least one other component, said process comprising providing an additional degree of freedom for adjusting the process parameters by:

(a) treating said feed gas mixture in a non-membrane separation unit to produce a helium-enriched stream and a helium-depleted stream;

(b) withdrawing at least a portion of the helium-enriched stream from the non-membrane separation unit;

(c) feeding said portion of said helium-enriched stream to a membrane separation unit, wherein said helium-enriched stream is separated to form a helium-rich stream and a helium-lean stream;

(d) recycling the helium-lean stream to the non-membrane separation unit for further treatment and separation to produce a helium-depleted stream; and

(e) recovering the helium-rich stream from the membrane separation unit.

2. The process in accordance with claim 1 wherein the helium depleted stream produced in step (a) is combined with the helium-depleted stream produced in step (d) and subsequently recovered as product.

3. The process in accordance with claim 1 wherein the helium-rich stream from the membrane unit is the permeate stream and the helium-lean stream is the reject stream.

4. The process in accordance with claim 1 wherein a helium-rich stream is produced in the non-membrane separation unit and is combined with the helium-rich stream from the membrane unit to form a combined helium product stream.

5. The process in accordance with claim 1, wherein said nonmembrane separation unit is a cryogenic-type separation unit.

6. The process in accordance with claim 1 wherein the helium-lean stream from the membrane unit is passed through a compressor prior to being returned to the non-membrane separation unit.

7. The process in accordance with claim 1 wherein the membrane separation unit comprises a cascade of membranes with internal recycle streams between various stages of the membrane unit.

8. The process in accordance with claim 4 wherein the helium-rich stream from the membrane unit is passed through a compressor prior to being combined with the second helium-rich stream produced in the nonmembrane separation unit.

9. The process in accordance with claim 1 wherein the feed gas mixture is selected from the group consisting of:

natural gas, a slip stream from a nitrogen rejection unit, liquid natural gas, crude helium gas and pipeline gas.

10. The process in accordance with claim 1 wherein the feed gas mixture is passed through a membrane separation unit to remove a portion of the helium as a helium-rich product stream prior to being treated in the non-membrane separation unit.

11. The process in accordance with claim 10 wherein the feed gas mixture has a helium concentration of at least 25 mole %.

12. The process in accordance with claim 1 wherein the feed gas mixture is passed through a first membrane separation unit to remove a portion of the non-helium components prior to being treated in the non-membrane separation unit.

13. The process in accordance with claim 12 wherein the helium-depleted stream from the non-membrane unit is recycled back to the first membrane separation unit.

14. The process in accordance with claim 13 wherein the feed gas mixture has a helium concentration of less than 5.0 mole %.

15. The process in accordance with claim 1 wherein the helium-rich stream from the membrane separation unit is passed to a second non-membrane separation unit for further purification.

16. The process in accordance with claim 15 wherein said second non-membrane separation unit is a PSA unit.

17. A process for recovering helium from a feed gas mixture comprising helium and at least one other component, said process comprising providing an additional degree of freedom for adjusting the process parameters by:

(a) passing said feed gas mixture through a first membrane separation unit to form a first helium-rich stream and a first helium-lean stream;

(b) treating said helium-lean stream in a non-membrane separation unit to produce a helium-enriched stream and a helium-depleted stream;

(c) withdrawing at least a portion of the helium-enriched stream from the non-membrane separation unit;

(d) feeding said portion of said helium-enriched stream to a second membrane unit wherein said helium-enriched stream is separated to form a second helium-rich stream and a second helium-lean stream;

(e) recycling the second helium-lean stream to the non-membrane separation unit for further treatment and separation to produce a helium-depleted stream; and

(f) recovering both helium-rich streams.

18. The process in accordance with claim 17 wherein the helium-depleted stream produced in step (b) is combined with the helium-depleted stream produced in step (e) and subsequently recovered as product.

19. The process in accordance with claim 17 wherein said nonmembrane separation unit is a cryogenic-type separation unit.

20. The process in accordance with claim 17 wherein a third helium-rich stream is produced in the non-membrane separation unit and is combined with both of the helium-rich streams from the membrane separation units to form a combined helium-rich product stream.

21. The process in accordance with claim 17 wherein the first and second membrane units are part of a single membrane separation unit with the feed gas and the portion of the helium-enriched gas stream from the non-membrane separation entering the single membrane unit at different locations along the unit.

22. The process in accordance with claim 17 wherein the helium-rich streams from the membrane units are permeate streams and the helium-lean streams are reject streams.