Integrated gas separation process

Claim 2

A process for separating components of a gas stream containing at least two components having different permeability through a given membrane, said process comprising: a) feeding said gas stream to a non-membrane separation unit to treat said gas stream: b) withdrawing at least a portion of the treated gas stream from the non-membrane separation unit; c) feeding said portion of the treated gas stream to a membane unit to form a permeate stream and a reject stream: d) returning at least one of the streams from the membrane unit to the non-membrane separation unit for further treatment and separation to form a purified stream: e) subsequently recovering said purified stream as a gaseous and/or liquid product.

Claim 3

A process for the production of gaseous and/or liquid nitrogen from a feed gas stream comprising nitrogen and oxygen, said process comprising: a) feeding said feed gas stream comprising nitrogen and oxygen to a cryogenic separation unit to treat said gas stream: b) withdrawing at least a portion of the treated gas stream from the cryogenic separation unit; c) feeding said portion of the treated gas stream to a membrane unit wherein said stream is separated to form a nitrogen-rich stream and an oxygen-rich stream; d) returning said nitrogen-rich stream to the cryogenic separation unit for further treatment and separation; and e) subsequently recovering a purified liquid and/or gaseous nitrogen-rich product stream.

Claim 4

A process for the production of gaseous and/or liquid nitrogen from a feed gas stream comprising nitrogen and oxygen, said process comprising: a) feeding said feed gas stream comprising nitrogen and oxygen to a cryogenic separation unit to treat said gas stream: b) withdrawing at least a portion of the treated gas stream from the cryogenic separation unit; c) feeding said portion of the treated gas stream to a membrane unit wherein said stream is separated to form a nitrogen-rich stream and an oxygen-rich stream; d) returning said nitrogen-rich stream to the cryogenic separation unit for further treatment and separation; and e) subsequently recovering a purified liquid and/or gaseous nitrogen-rich product stream.

Claim 5

The process in accordance with Claim 2 wherein at least a portion of said oxygen-rich stream is returned to the cryogenic separation unit for further processing.

Claim 6

The process in accordance with Claim 2 wherein the feed gas stream comprising nitrogen and oxygen is air.

Claim 7

The process in accordance with Claim 4 wherein the feed gas stream is passed through an H 2 0 and C0 2 removal unit prior to being fed to the cryogenic separation unit.

Claim 8

The process in accordance with Claim 5 wherein said H 2 0 and C0 2 removal unit contains one or more molecular sieve beds.

Claim 9

The process in accordance with Claim 2 wherein the total nitrogen recovery, based on the feed stream, is at least 75%.

Claim 10

The process in accordance with Claim 2 wherein the nitrogen product has a purity of at least 99.7%.

Claim 11

A process for the production of liquid nitrogen from an air feed stream, said process comprising: a) passing said air feed stream through a molecular sieve bed to remove water and carbon dioxide, thereby producing a nitrogen/oxygen-rich gas stream; b) condensing at least a portion of the nitrogen/oxygen-rich gas stream in a cryogenic processing unit to produce a liquid nitrogen/oxygen stream; c) passing said liquid nitrogen/oxygen stream to a distillation column where it is treated to form an oxygen-rich liquid stream and a gaseous nitrogen stream: d) condensing said gaseous nitrogen stream to produce a liquid nitrogen stream; e) reducing the pressure of said liquid nitrogen stream to produce a nitrogen product stream: f) vaporizing said oxygen-rich liquid stream in step (c) to form a gaseous oxygen-rich stream; g) passing said gaseous oxygen-rich stream to a membrane unit for separation into an oxygen-rich permeate stream and a nitrogen-containing reject stream; and h) passing said nitrogen-containing reject stream back through the cryogenic processing unit.

Claim 12

A process for the production of liquid nitrogen from an air feed stream, said process comprising: a) passing said air feed stream through a molecular sieve bed to remove water and carbon dioxide, thereby producing a nitrogen/oxygen-rich gas stream; b) condensing at least a portion of the nitrogen/oxygen-rich gas stream in a cryogenic processing unit to produce a liquid nitrogen/oxygen stream; c) passing said liquid nitrogen/oxygen stream to a distillation column where it is treated to form an oxygen-rich liquid stream and a gaseous nitrogen stream: d) condensing said gaseous nitrogen stream to produce a liquid nitrogen stream; e) reducing the pressure of said liquid nitrogen stream to produce a nitrogen product stream: f) vaporizing said oxygen-rich liquid stream in step (c) to form a gaseous oxygen-rich stream; g) passing said gaseous oxygen-rich stream to a membrane unit for separation into an oxygen-rich permeate stream and a nitrogen-containing reject stream; and h) passing said nitrogen-containing reject stream back through the cryogenic processing unit.

Claim 13

The process in accordance with Claim 9 wherein the pressure of the gaseous oxygen-rich stream passed to the membrane unit is chosen such that the pressure of the nitrogen-containing reject stream from the membrane unit is about the same as the pressure of the nitrogen/oxygen-rich gas stream leaving the molecular sieve bed.

Claim 14

The process in accordance with Claim 9 wherein the pressure of the gaseous oxygen-rich stream passed to the membrane unit is chosen such that the pressure of the nitrogen-containing reject stream from the membrane unit is significantly higher than the pressure of the nitrogen/oxygen-rich gas stream leaving the molecular sieve bed.

Claim 15

A process for the production of gaseous nitrogen from an air feed stream, said process comprising: a) passing said air feed stream through a molecular sieve bed to remove water and carbon dioxide, thereby producing a nitrogen/oxygen-rich gas stream; b) cooling said nitrogen/oxygen-rich gas stream; c) treating said cooled nitrogen/oxygen-rich gas stream in a distillation column to remove nitrogen thereby forming an oxygen-rich stream; d) passing said oxygen-rich stream to a membrane unit where it is separated to form a permeate stream and a reject stream; e) returning said reject stream to the distillation column where it is treated along with the nitrogen/oxygen-rich gas stream of step (c) to form a nitrogen-rich stream; f) withdrawing said nitrogen-rich stream from the distillation column; and g) heating said nitrogen-rich stream in a series of heat exchangers to produce a gaseous nitrogen product stream.

Claim 16

A process for the production of gaseous nitrogen from an air feed stream, said process comprising: a) passing said air feed stream through a molecular sieve bed to remove water and carbon dioxide, thereby producing a nitrogen/oxygen-rich gas stream; b) cooling said nitrogen/oxygen-rich gas stream; c) treating said cooled nitrogen/oxygen-rich gas stream in a distillation column to remove nitrogen thereby forming an oxygen-rich stream; d) passing said oxygen-rich stream to a membrane unit where it is separated to form a permeate stream and a reject stream; e) returning said reject stream to the distillation column where it is treated along with the nitrogen/oxygen-rich gas stream of step (c) to form a nitrogen-rich stream; f) withdrawing said nitrogen-rich stream from the distillation column; and g) heating said nitrogen-rich stream in a series of heat exchangers to produce a gaseous nitrogen product stream.

Claim 17

A process for recovering hydrogen from a feed gas mixture comprising hydrogen and at least one other component, said process comprising: a) treating said feed gas mixture in a non-membrane separation unit to produce a hydrogen-enriched stream and a hydrogen-depleted stream: b) withdrawing at least a portion of the hydrogen-enriched stream from the non-membrane separation unit; c) feeding said portion of said hydrogen-enriched stream to a membrane separation unit, wherein said hydrogen-enriched stream is separated to form a hydrogen-rich stream and a hydrogen-lean stream: d) recycling the hydrogen-lean stream to the non-membrane separation unit for further treatment and separation to produce a hydrogen-depleted stream: and e) recovering the hydrogen-rich stream from the membrane separation unit.

Claim 18

A process for recovering hydrogen from a feed gas mixture comprising hydrogen and at least one other component, said process comprising: a) treating said feed gas mixture in a non-membrane separation unit to produce a hydrogen-enriched stream and a hydrogen-depleted stream: b) withdrawing at least a portion of the hydrogen-enriched stream from the non-membrane separation unit; c) feeding said portion of said hydrogen-enriched stream to a membrane separation unit, wherein said hydrogen-enriched stream is separated to form a hydrogen-rich stream and a hydrogen-lean stream: d) recycling the hydrogen-lean stream to the non-membrane separation unit for further treatment and separation to produce a hydrogen-depleted stream: and e) recovering the hydrogen-rich stream from the membrane separation unit.

Claim 19

The process in accordance with Claim 13 wherein the hydrogen-depleted stream produced in step (a) is combined with the hydrogen-depleted stream produced in step (d) and subsequently recovered as product.

Claim 20

The process in accordance with Claim 13 wherein the hydrogen-rich stream from the membrane unit is the permeate stream from the membrane and the hydrogen-lean stream is the reject stream.

Claim 21

The process in accordance with Claim 13 wherein a hydrogen-rich stream is produced in the non-membrane separation unit and is combined with the hydrogen-rich stream from the membrane unit to form a combined hydrogen product stream.

Claim 22

The process in accordance with Claim 13, wherein said non-membrane separation unit is a cryogenic-type separation unit.

Claim 23

The process in accordance with Claim 13 wherein the membrane separation unit comprises a cascade of membranes with internal recycle streams between various stages of the membrane unit.

Claim 24

The process in accordance with Claim 13 wherein the feed gas mixture is passed through a membrane separation unit to remove a portion of the hydrogen prior to being treated in the non-membrane separation unit.

Claim 25

A process for recovering hydrogen from a feed gas mixture comprising hydrogen and at least one other component, said process comprising; a) passing said feed gas mixture through a first membrane separation unit to form a first hydrogen-rich stream and a first hydrogen-lean stream; b) treating said hydrogen-lean stream in a non-membrane separation unit to produce a hydrogen-enriched stream and a hydrogen-depleted stream; c) withdrawing at least a portion of the hydrogen-enriched stream from the non-membrane separation unit; d) feeding said portion of said hydrogen-enriched stream to a second membrane unit wherein said hydrogen-enriched stream is separated to form a second hydrogen-rich stream and a second hydrogen-lean stream: e) recycling the second hydrogen-lean stream to the non-membrane separation unit for further treatment and separation to produce a hydrogen-depleted stream; and f) recovering both hydrogen-rich streams.

Claim 26

A process for recovering hydrogen from a feed gas mixture comprising hydrogen and at least one other component, said process comprising; a) passing said feed gas mixture through a first membrane separation unit to form a first hydrogen-rich stream and a first hydrogen-lean stream; b) treating said hydrogen-lean stream in a non-membrane separation unit to produce a hydrogen-enriched stream and a hydrogen-depleted stream; c) withdrawing at least a portion of the hydrogen-enriched stream from the non-membrane separation unit; d) feeding said portion of said hydrogen-enriched stream to a second membrane unit wherein said hydrogen-enriched stream is separated to form a second hydrogen-rich stream and a second hydrogen-lean stream: e) recycling the second hydrogen-lean stream to the non-membrane separation unit for further treatment and separation to produce a hydrogen-depleted stream; and f) recovering both hydrogen-rich streams.

Claim 27

The process in accordance with Claim 20 wherein the hydrogen-depleted stream produced in step (b) is combined with the hydrogen-depleted stream produced in step (e) and subsequently recovered as product.

Claim 28

The process in accordance with Claim 20 wherein said non-membrane separation unit is a cryogenic-type separation unit.

Claim 29

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

Claim 30

The process in accordance with Claim 20 wherein the first and second hydrogen-rich streams are combined and passed through a compressor prior to being combined with the third hydrogen-rich stream.

Claim 31

The process in accordance with Claim 20 wherein the feed gas mixture comprises hydrogen, hydrogen sulfide, methane and heavier hydrocarbons.

Claim 32

The process in accordance with Claim 20 wherein vacuum pumps are used to achieve sub-atmospheric pressure on the permeate side of the membrane units.

Claim 33

The process in accordance with Claim 20 wherein the first and second membrane units are part of a single membrane separation unit with the feed gas and the portion of the treated gas stream from the non-membrane separation entering the single membrane unit at different locations along the unit.

Claim 34

The process in accordance with Claim 27 wherein the single membrane separation unit comprises a cascade of membranes with internal recycles.

Claim 35

The process in accordance with Claim 20 wherein the hydrogen-rich streams from the membrane units are permeate streams and the hydrogen-lean streams are reject streams.