Filing Information

Inventor(s)	Rakesh Agrawal · Steven R. Auvil ·
Assignee(s)	Air Products and Chemicals, Inc. ·  View assignee updates
Attorney/Agent(s)	Mark L. Rodgers ·
Primary Examiner	Frank Sever ·
Application Number	US6684655
Filing date	12/21/1984
Issue date	06/17/1986
Predicted expiration date	12/21/2004
U.S. Classifications	62/646  · 62/655  · 62/939  ·
International Classifications	F25J 304  ·
Kind Code	A
International Classifications	6223-33;38;39;18;19 ·

Patent Family

Abstract

The present invention involves an efficient process for separating components of a gas stream by integrating a cryogenic separation unit and a membrane separation unit. One embodiment provides for the generation of one or more nitrogen-rich streams in the gas or liquid phase, or both, from a stream comprising oxygen and nitrogen; e.g., air.

Independent Claims | See all claims (18)

1. 1. 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.
2. 14. 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.
3. 17. 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.
4. 18.18. 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.