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US 2021/0123671 A1Published application
Method and apparatus for separating air by cryogenic distillation
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsBertrand DEMOLLIENS, Patrick LE BOT
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Abstract
In a method for separating air by cryogenic distillation, cooled air purified to remove water is sent to a first column operating at a first pressure, where it is separated into a nitrogen-enriched gas as an oxygen-enriched liquid; a gas enriched in argon relative to the air is withdrawn from the second column; at least a portion of the oxygen-enriched liquid is vaporized by heat exchange with the argon-enriched gas; and the vaporized, oxygen-enriched liquid is sent to an intermediate level of the second column.
Claims13
A method for separating air by cryogenic distillation, the method comprising the steps of:
- (a) sending a cooled air that has previous been purified to remove water to a first column operating at a first pressure, where the cooled air is separated into a nitrogen-enriched gas and an oxygen-enriched liquid;
- (b) withdrawing a liquid enriched in nitrogen relative to the air from the first column and sending said liquid enriched in nitrogen to the top of a second column that is connected thermally to the first column and operates at a second pressure, wherein the second pressure is lower than the first pressure;
- (c) withdrawing a liquid enriched in oxygen relative to the air from the first column;
- (d) withdrawing a gas enriched in argon relative to the air from the second column;
- (e) at least partially vaporizing at least a portion of the oxygen-enriched liquid by heat exchange with the argon-enriched gas to form a vaporized oxygen-enriched fluid, and then sending the vaporized oxygen-enriched fluid to an intermediate level of the second column;
- (f) returning at least one condensed portion of the argon-enriched gas to a third column, wherein the third column is also fed with an argon-enriched gas flow originating from the second column, wherein an argon-enriched top gas is withdrawn at a top portion of the third column, and an argon-depleted liquid is returned from the third column to the second column;
- (g) sending a portion of the oxygen-enriched liquid to an overhead condenser of the third column;
- (h) vaporizing the oxygen-enriched liquid sent to the overhead condenser in the overhead condenser and then sending the resulting oxygen-enriched vapor to the second column,
- wherein the portion of the oxygen-enriched liquid that is sent to the overhead condenser of the third column has not been reheated against the argon-enriched gas flow.
6 more elements
An apparatus for separating air by cryogenic distillation, the apparatus comprising:
- a first column operating at a first pressure;
- a second column connected thermally to the first column and operating at a second pressure, which is lower than the first pressure;
- a heat exchanger;
- means for sending cooled air that has been purified to remove water, to the first column, operating at a first pressure, where the cooled air is separated into a nitrogen-enriched gas and an oxygen-enriched liquid;
- means for withdrawing a liquid enriched in nitrogen relative to the air from the first column;
- means for sending the nitrogen-enriched liquid to the top of the second column;
- means for withdrawing a liquid enriched in oxygen relative to the air from the first column;
- means for withdrawing a gas enriched in argon relative to the air from the second column;
- means for sending a portion of the oxygen-enriched liquid to the heat exchanger for at least partial vaporization thereof by heat exchange with the argon-enriched gas;
- means for sending the oxygen-enriched liquid vaporized in the heat exchanger to an intermediate level of the second column;
- a third column;
- means for sending at least one condensed portion of the argon-enriched gas in the heat exchanger to the third column;
- and
- means for sending an argon-enriched gas flow originating from the second column to the third column;
- means for withdrawing an argon-enriched flow at the top of the third column;
- means for sending an argon-depleted liquid from the third column to the second column;
- means for sending a portion of the oxygen-enriched liquid to an overhead condenser of the third column;
- and
- means for sending the vapour produced by vaporizing the oxygen-enriched liquid in the overhead condenser to the second column;
- wherein the means for sending the portion of the oxygen-enriched liquid to the overhead condenser are connected directly to the first column without passing via the heat exchanger.
17 more elements
Dependencies are inferred from the claim text.