Process for recovering helium from a multi-component gas stream

Claim 2

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.

Claim 3

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.

Claim 4

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.

Claim 5

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.

Claim 6

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

Claim 7

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.

Claim 8

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.

Claim 9

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.

Claim 10

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.

Claim 11

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.

Claim 12

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

Claim 13

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.

Claim 14

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.

Claim 15

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

Claim 16

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.

Claim 17

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

Claim 18

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.

Claim 19

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.

Claim 20

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.

Claim 21

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

Claim 22

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.

Claim 23

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.

Claim 24

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.