Process for the generation of gaseous and/or liquid nitrogen
AssigneeAir Products and Chemicals, Inc.
InventorsRakesh Agrawal, Steven R. Auvil
Life of this patent
Estimating the term…
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.
Claims18
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.
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.
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.
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.
Dependencies are inferred from the claim text.