Helium recovery from streams containing helium, carbon dioxide, and at least one of nitrogen and methane

1. A method for recovering helium from a feed stream containing helium, carbon dioxide and at least one of methane and nitrogen, the method comprising:

introducing a separator feed stream into a separator, the separator feed stream comprising at least a portion of the feed stream, separating the separator feed stream into a first helium-enriched stream and a first CO 2 -enriched stream, and withdrawing the first helium-enriched stream and the first CO 2 -enriched stream from the separator;

introducing a pressure swing adsorption unit feed stream into a pressure swing adsorption unit, the pressure swing adsorption unit feed stream comprising at least a portion of the first helium-enriched stream, separating the pressure swing adsorption unit feed stream into a helium-rich product stream and a helium-lean stream, and withdrawing the helium-rich product stream and the helium-lean stream from the pressure swing adsorption unit;

compressing a compressor feed stream in a compressor to form a compressor effluent stream, the compressor feed stream comprising the helium-lean stream and a helium-enriched permeate stream;

introducing a first portion of the compressor effluent stream into a membrane separation unit, separating the first portion of the compressor effluent stream to form the helium-enriched permeate stream and a helium-depleted non-permeate stream, and withdrawing the helium-enriched permeate stream and the helium-depleted non-permeate stream from the membrane separation unit; and

introducing a second portion of the compressor effluent stream into the separator.

2. The method of claim 1 wherein the first portion of the compressor effluent stream has a molar flow rate, F 1 , the second portion of the compressor effluent stream has a molar flow rate, F 2 , and wherein

0.60

≤

F

1

F

2

≤

0.85

.

3. The method of claim 1 wherein the membrane separation unit comprises a separation module wherein the separation module is a hollow fiber module or a spiral wound module.

4. The method of claim 3 wherein the separation module comprises a membrane, wherein the membrane comprises a support, wherein the support comprises a material selected from the group consisting of polysulfone, cellulose acetate, an aromatic polyimide, an aromatic polyamide, an aromatic polycarbonate, poly(dimethyl phenylene oxide), poly(dimethyl siloxane), and carbon molecular sieve.

5. The method of claim 4 wherein the separation membrane is a mixed matrix membrane.

6. The method of claim 4 wherein the separation membrane is a facilitated transport membrane.

7. The method of claim 1 wherein the separator is a pressure swing adsorption separator.

8. The method of claim 1 wherein the separator is a fractionator.

9. The method of claim 8 , wherein the fractionator is a distillation column, wherein the first helium-enriched stream is withdrawn from an upper location of the distillation column, and the first CO 2 -enriched stream is withdrawn from a lower location of the distillation column, the method further comprising the steps of:

cooling the feed stream to form the separator feed stream; and

feeding a liquid stream comprising CO 2 to an upper portion of the distillation column as a CO 2 wash stream;

wherein at least part of the separator feed stream is introduced into the distillation column at an location intermediate the upper location of the distillation column and the lower location of the distillation column.

10. A system for recovering helium from a feed stream containing helium, carbon dioxide and at least one of methane and nitrogen, the system comprising:

a separator operatively disposed to receive a separator feed stream, the separator feed stream comprising at least a portion of the feed stream, the separator operatively configured to separate the separator feed stream into a first helium-enriched stream and a first CO 2 -enriched stream;

a pressure swing adsorption unit operatively configured to separate a pressure swing adsorption unit feed stream into a helium-rich product stream and a helium-lean stream, the pressure swing adsorption unit feed stream comprising at least a portion of the first helium-enriched stream;

a compressor operatively disposed to receive a compressor feed stream comprising the helium-lean stream and a helium-enriched permeate stream, the compressor operatively configured to compress the compressor feed stream to form a compressor effluent stream; and

a membrane separation unit operatively disposed to receive a first portion of the compressor effluent stream and operatively configured to separate the first portion of the compressor effluent stream into the helium-enriched permeate stream and a helium-depleted non-permeate stream;

wherein the separator is also operatively disposed to receive a second portion of the compressor effluent stream.

11. The system of claim 10 wherein the membrane separation unit comprises a separation membrane wherein the separation membrane is a hollow fiber membrane or a spiral wound membrane.

12. The system of claim 11 wherein the separation membrane comprises a support, wherein the support comprises a material selected from the group consisting of polysulfone, cellulose acetate, an aromatic polyimide, an aromatic polyamide, an aromatic polycarbonate, poly(dimethyl phenylene oxide), poly(dimethyl siloxane), and carbon.

13. The system of claim 11 wherein the separation membrane is a mixed matrix membrane.

14. The system of claim 11 wherein the separation membrane is a facilitated transport membrane.

15. The system of claim 10 wherein the separator is a pressure swing adsorption separator.

16. The system of claim 10 wherein the separator is a fractionator.

17. The system of claim 16 wherein the fractionator is a distillation column,

wherein the distillation column has a first outlet operatively disposed to withdraw the first helium-enriched stream, the first outlet located in an upper portion of the distillation column;

wherein the distillation column has a second outlet operatively disposed to withdraw the first CO 2 -enriched stream, the second outlet located in a lower portion of the distillation column;

wherein the distillation column has a first inlet operatively disposed to introduce the separator feed stream, the first inlet located at a position intermediate the upper portion of the distillation column and the lower portion of the distillation column;

wherein the distillation column has a second inlet operatively disposed to introduce a CO 2 wash stream, the second inlet located in the upper portion of the distillation column;

the system further comprising:

one or more heat exchangers operatively configured to cool the at least a portion of the feed stream to form the separator feed stream by indirect heat transfer with a portion or all of the first helium-enriched stream and a portion or all of the first CO 2 -enriched stream thereby heating the portion or all of the first helium-enriched stream and the portion or all of the first CO 2 -enriched stream.

18. The system of claim 10 , wherein the first helium-enriched stream comprises one or more combustible components, the system further comprising a catalytic combustor operatively configured to combust the one or more combustible components in the first helium-enriched stream in the presence of oxygen to at least partially convert the combustible components to CO 2 and H 2 O thereby forming a combustible component-depleted helium-enriched stream wherein the pressure swing adsorption unit feed stream comprises the combustible component-depleted helium-enriched stream as the at least a portion of the first helium-enriched stream.