US 4,715,873 A · Liquefied gases using an air recycle liquefier

Abstract

Liquid nitrogen, oxygen and/or argon is produced from a cryogenic distillative separation efficiently and economically wherein at least a portion of the liquid air feed bypasses the distillation column and is used to liquefy the gaseous product of the column, and the recycle air stream resulting therefrom is retained at elevated pressure.

Claims26

Dependent claims

In a process for the cryogenic distillative separation of air by fractionation in a distillation column to produce at least one liquid product stream selected from the group consisting of liquid nitrogen, liquid oxygen and/or liquid argon, the improvement comprising:

(a) cooling a feed air stream by appropriate refrigeration to produce at least a portion of the feed air stream as a liquid air stream;
(b) condensing a product stream against at least a portion of the liquid air stream by indirect heat exchange thereby vaporizing the liquid air stream to produce a substantially gaseous air stream and a liquid product stream;
(c) further processing at least a portion of the substantially gaseous air stream by recycling it to feed air.

A process for the cryogenic distillative separation of air to produce at least a liquid nitrogen product, comprising the steps of:

(a) compressing feed air to an elevated pressure and removing water, carbon dioxide and condensibles from the feed air;
(b) splitting the feed air into a first split feed stream and a second split feed stream;
(c) cooling each split feed stream to a lower temperature by indirect heat exchange against process streams;
(d) expanding a first portion of the first split feed stream through a warm expander and recycling at least a first part of the expanded stream to the feed air while providing refrigeration to the feed air by indirect heat exchange;
(e) expanding the second split feed stream through a cold expander and using at least a first portion of the expanded stream for a distillation step;
(f) recycling a second portion of the expanded second split stream to the feed air while providing refrigeration to the feed air by indirect heat exchange;
(g) removing an oxygen-enriched stream from the base of the distillation column;
(h) removing a gaseous nitrogen stream from the distillation column and condensing a first portion of the gaseous nitrogen stream against a process stream;
(i) condensing a second portion of the gaseous nitrogen stream from the distillation column against at least a part of the second portion of the first split stream by indirect heat exchange to produce a liquid nitrogen product, and
(j) recycling at least a part of the second portion of the first split stream to the feed air.

7 more elements

A process for the cryogenic distillative separation of air to produce at least a liquid nitrogen product comprising the steps of:

(a) compressing feed air to an elevated pressure and removing water, carbon dioxide and condensibles from the feed air;
(b) splitting the feed air into a first split feed stream and a second split feed stream;
(c) cooling each split feed stream to a lower temperature by indirect heat exchange against process streams;
(d) expanding a first portion of the first split feed stream through a warm expander and recycling a first part of the expanded stream to feed air while providing refrigeration to the feed air by indirect heat exchange;
(e) expanding the second split feed stream through a cold expander and introducing a first portion of the expanded stream into a boiler/condenser in the base of a distillation column to provide boil-up in the column and at least partially condense said expanded first portion;
(f) cooling and phase separating a second portion of the first split stream and combining the vapor phase of said second portion with said first portion of the expanded stream of step (e) before its introduction into the boiler/condenser;
(g) combining the liquid phase of the second portion of the first split stream with the at least partially condensed expanded first portion stream from said boiler/condenser of step (e) and phase separating the combined stream into a vapor phase feed stream and a liquid phase feed stream;
(h) introducing the vapor phase feed stream of step (g) into the distillation column for rectification, and
(i) removing a gaseous nitrogen stream from the top of the distillation column, condensing a portion of the gaseous nitrogen against oxygen-enriched liquid from the base of the distillation column and condensing another portion of the gaseous nitrogen stream against the liquid phase feed stream of step (g) by indirect heat exchange in a side column to produce a liquid nitrogen product and a gaseous recycle stream to the feed air.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application

06/855,859Filed 24 Apr 1986

Granted

29 Dec 1987

Term ends

Not estimatedThe source records don’t support an estimate.

Classification25 codes

F25J 3/0423
Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams: subcooling of liquid process streams
F25J 3/042
Division of the main heat exchange line in consecutive sections having different functions: having an intermediate feed connection
F25J 3/04212
Including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product: and simultaneously condensing vapor from a column…
F25J 3/04296
Of feed air, e.g. used as waste or product air or expanded into an auxiliary column: claude expansion, i.e. expanded into the main or high…

Abstract

Claims26

Dependent claims

(a) cooling a feed air stream by appropriate refrigeration to produce at least a portion of the feed air stream as a liquid air stream;
(b) condensing a product stream against at least a portion of the liquid air stream by indirect heat exchange thereby vaporizing the liquid air stream to produce a substantially gaseous air stream and a liquid product stream;
(c) further processing at least a portion of the substantially gaseous air stream by recycling it to feed air.

A process for the cryogenic distillative separation of air to produce at least a liquid nitrogen product, comprising the steps of:

(a) compressing feed air to an elevated pressure and removing water, carbon dioxide and condensibles from the feed air;
(b) splitting the feed air into a first split feed stream and a second split feed stream;
(c) cooling each split feed stream to a lower temperature by indirect heat exchange against process streams;
(d) expanding a first portion of the first split feed stream through a warm expander and recycling at least a first part of the expanded stream to the feed air while providing refrigeration to the feed air by indirect heat exchange;
(e) expanding the second split feed stream through a cold expander and using at least a first portion of the expanded stream for a distillation step;
(f) recycling a second portion of the expanded second split stream to the feed air while providing refrigeration to the feed air by indirect heat exchange;
(g) removing an oxygen-enriched stream from the base of the distillation column;
(h) removing a gaseous nitrogen stream from the distillation column and condensing a first portion of the gaseous nitrogen stream against a process stream;
(i) condensing a second portion of the gaseous nitrogen stream from the distillation column against at least a part of the second portion of the first split stream by indirect heat exchange to produce a liquid nitrogen product, and
(j) recycling at least a part of the second portion of the first split stream to the feed air.

7 more elements

A process for the cryogenic distillative separation of air to produce at least a liquid nitrogen product comprising the steps of:

(a) compressing feed air to an elevated pressure and removing water, carbon dioxide and condensibles from the feed air;
(b) splitting the feed air into a first split feed stream and a second split feed stream;
(c) cooling each split feed stream to a lower temperature by indirect heat exchange against process streams;
(d) expanding a first portion of the first split feed stream through a warm expander and recycling a first part of the expanded stream to feed air while providing refrigeration to the feed air by indirect heat exchange;
(e) expanding the second split feed stream through a cold expander and introducing a first portion of the expanded stream into a boiler/condenser in the base of a distillation column to provide boil-up in the column and at least partially condense said expanded first portion;
(f) cooling and phase separating a second portion of the first split stream and combining the vapor phase of said second portion with said first portion of the expanded stream of step (e) before its introduction into the boiler/condenser;
(g) combining the liquid phase of the second portion of the first split stream with the at least partially condensed expanded first portion stream from said boiler/condenser of step (e) and phase separating the combined stream into a vapor phase feed stream and a liquid phase feed stream;
(h) introducing the vapor phase feed stream of step (g) into the distillation column for rectification, and
(i) removing a gaseous nitrogen stream from the top of the distillation column, condensing a portion of the gaseous nitrogen against oxygen-enriched liquid from the base of the distillation column and condensing another portion of the gaseous nitrogen stream against the liquid phase feed stream of step (g) by indirect heat exchange in a side column to produce a liquid nitrogen product and a gaseous recycle stream to the feed air.

6 more elements

Dependencies are inferred from the claim text.

Liquefied gases using an air recycle liquefier

Life of this patent

Abstract

Claims26

Liquefied gases using an air recycle liquefier

Life of this patent

Abstract

Claims26