Process for the generation of gaseous and/or liquid nitrogen

Claim 2

A process for the production of gaseous and/or liquid nitrogen from a feed gas stream comprising nitrogen and oxygen, said process comprising providing an additional degree of freedom for adjusting the process parameters by: (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 3

The process in accordance with claim 1 wherein at least a portion of said oxygen-rich stream is returned to the cryogenic separation unit for further processing.

Claim 4

The process in accordance with claim 2 wherein said oxygen-rich stream is passed through a compressor prior to being returned to the cryogenic separation unit.

Claim 5

The process in accordance with claim 1 wherein the feed gas stream comprising nitrogen and oxygen is air.

Claim 6

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

Claim 7

The process in accordance with claim 5 wherein said H 2 O and CO 2 removal unit contains one or more molecular sieve beds.

Claim 8

The process in accordance with claim 6 wherein a portion of said oxygen-rich stream is used to regenerate the molecular sieve beds.

Claim 9

The process in accordance with claim 7 wherein said feed gas stream is passed through a compressor prior to entering the H 2 O and CO 2 removal unit.

Claim 10

The process in accordance with claim 1 wherein said treated gas stream which is withdrawn from the cryogenic separation unit is passed through a compressor prior to entering the membrane unit.

Claim 11

The process in accordance with claim 1 wherein said nitrogen-rich stream from the membrane unit is passed through a compressor prior to being returned to the cryogenic separation unit.

Claim 12

The process in accordance with claim 1 wherein the total nitrogen recovery, based on the feed stream, is at least 75%.

Claim 13

The process in accordance with claim 1 wherein the nitrogen product has a purity of at least 99.7%.

Claim 14

The process in accordance with claim 1 wherein the oxygen-rich stream is recovered as product.

Claim 15

A process for the production of liquid nitrogen from an air feed stream, said process comprising providing an additional degree of freedom for adjusting the process parameters by: (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 a 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 16

A process for the production of liquid nitrogen from an air feed stream, said process comprising providing an additional degree of freedom for adjusting the process parameters by: (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 a 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 17

The process in accordance with claim 14 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 18

The process in accordance with claim 14 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 19

A process for the production of gaseous nitrogen from an air feed stream, said process comprising providing an additional degree of freedom for adjusting the process parameters by: (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 20

A process for the production of gaseous nitrogen from an air feed stream, said process comprising providing an additional degree of freedom for adjusting the process parameters by: (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 21

A process for separating components of a gas stream containing at least two components having different permeability through a given membrane, process provides an additional degree of freedom for optimizing said process comprising providing an additional degree of freedom for adjusting the process parameters by: (a) feeding said gas stream 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 to form a premeate stream and a reject steam; (d) returning at least one of the streams from the membrane unit to the cryogenic separation unit for further treatment and separation to form a purified stream; and (e) subsequently recovering said purified stream as a gaseous and/or liquid product.

Claim 22

A process for separating components of a gas stream containing at least two components having different permeability through a given membrane, process provides an additional degree of freedom for optimizing said process comprising providing an additional degree of freedom for adjusting the process parameters by: (a) feeding said gas stream 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 to form a premeate stream and a reject steam; (d) returning at least one of the streams from the membrane unit to the cryogenic separation unit for further treatment and separation to form a purified stream; and (e) subsequently recovering said purified stream as a gaseous and/or liquid product.