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US 4,705,548 AGranted
Liquid products using an air and a nitrogen recycle liquefier
AssigneeAir Products and Chemicals, Inc.
InventorsRakesh Agrawal, Steven R. Auvil
Life of this patent
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Abstract
Liquid nitrogen, oxygen and/or argon are produced from a cryogenic distillative separation efficiently and economically using a combination of air recycle and nitrogen recycle to produce a liquid product.
Claims19
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) introducing at least a portion of the liquid air stream to the distillation column as feed;
- (c) producing a gaseous nitrogen stream from the distillation column and recycling at least a portion of said nitrogen stream to the process;
- (d) compressing the recycled nitrogen stream and reboiling a process stream with the recycle nitrogen stream to produce boil-up for the process and a condensed nitrogen stream, and
- (e) recovering at least a portion of the condensed recycle nitrogen as liquid nitrogen product.
2 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 at least a 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 at least a first portion of the gaseous nitrogen stream against a fluid of the distillation column to form a liquid nitrogen stream;
- (i) removing a second gaseous nitrogen stream from the distillation column and recycling said stream in heat exchange against process streams;
- (j) recompressing the second gaseous nitrogen stream and liquefying said stream against process fluid of the distillation column to form a second liquid nitrogen stream;
- and
- (k) recovering at least a portion of the liquid nitrogen of step (h) and/or step (j) as a liquid nitrogen product.
9 more elements
Dependencies are inferred from the claim text.