Helium extraction from natural gas

Patent metadata

Field	Value
Publication number	US-10962283-B2
Application number	US-201816130260-A
Country	US
Kind code	B2
Filing date	Sep 13, 2018
Priority date	Sep 13, 2018
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

A helium-containing stream is recovered from a natural gas feed using a membrane followed by multiple distillation steps. Refrigeration is provided by expanding a bottoms liquid with a higher nitrogen content than the feed, achieving a lower temperature in the process. The helium-enriched vapor is then purified and the helium-containing waste stream is recycled to maximize recovery and reduce the number of compressors needed. The helium-depleted natural gas stream can be returned at pressure for utilization or transportation.

First claim

We claim:

1. A process for recovering helium from a natural gas feed comprising methane, nitrogen, and helium, said process comprising:
introducing said natural gas feed to a membrane separation system to produce a helium-enriched permeate stream and a helium-depleted non-permeate stream;
compressing said helium-enriched permeate stream in a permeate compressor to produce a compressed permeate stream;
cooling said compressed permeate stream, or a stream derived from said compressed permeate stream, to produce a cooled permeate stream which is at least partially condensed;
separating said cooled permeate stream in a first distillation column system to produce a helium-enriched overhead vapor and a first helium-depleted bottoms liquid;
cooling said helium-enriched overhead vapor to produce a cooled overhead stream which is at least partially condensed;
separating said cooled overhead stream in a second distillation column system to produce a crude helium vapor and a second helium-depleted bottoms liquid;
and expanding at least a portion of the second helium depleted bottoms liquid to produce a low-temperature refrigerant;
wherein the cooling duty for cooling the helium-enriched overhead vapor is provided at least in part by indirect heat exchange with said low-temperature refrigerant;
warming at least a portion of said second helium-depleted bottoms liquid to produce a first return stream;
combining said first return stream with said first helium-depleted bottoms liquid to produce a second return stream;
and compressing and combining said second return stream with said low-temperature refrigerant and said helium-depleted non-permeate stream to produce a helium-depleted natural gas product.

2. Process of claim 1 wherein the pressure of said first distillation column is set to achieve a ratio of liquid to vapor density in the distillation column system greater than.

3. Process of claim 1 wherein the pressure of said first distillation column is set to achieve a liquid phase surface tension in the distillation column system greater than 0.5 dyne/cm.

4. Process of claim 1 further comprising the step of removing at least one of carbon dioxide, water, and heavy hydrocarbons from said compressed permeate stream.

5. Process of claim 1 wherein the re-boiling duty for said first distillation column system is provided at least in part by indirect heat exchange with the compressed permeate stream.

6. Process of claim 1 wherein the re-boiling duty for said second distillation column system is provided at least in part by indirect heat exchange with the helium-enriched overhead vapor.

7. Process of claim 1 wherein the cooling duty for cooling the compressed permeate stream is provided at least in part by indirect heat exchange with said second return stream.

8. Process of claim 1 further comprising the step of purifying the crude helium vapor to produce a pure helium product and a helium-depleted waste stream.

9. Process of claim 8 further comprising combining said helium-depleted waste stream with said helium-enriched permeate stream prior to entering, or at an interstage of, said permeate compressor.

10. Process of claim 8 wherein the crude helium vapor is purified in an adsorption system.

Assignees

• Air Prod & Chem

Inventors

• White Vincent
• Higginbotham Paul
• Ploeger Jason Michael

Classifications

• F25J2210/04

  Mixing or blending of fluids with the feed stream · CPC title

• F25J2230/32

  Compression of the product stream · CPC title

• F25J2270/02

  Internal refrigeration with liquid vaporising loop · CPC title

• F25J3/0233

  separation of CnHm with 1 carbon atom or more · CPC title

• F25J3/0257

  separation of nitrogen (from air F25J3/04, production of nitrogen in general C01B21/00) · CPC title