Method and apparatus for separating air by cryogenic distillation
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorBenoit Davidian
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Abstract
The invention relates to a method for separating air by cryogenic distillation in a column system, comprising a first column operating at a first pressure and a second column operating at a second pressure, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.
Claims15
A method for separating air by cryogenic distillation in a column system comprising a first column operating at a first pressure and a second column operating at a second pressure, the first pressure being substantially equal to the second pressure, wherein:
- (a) sending compressed, purified and cooled air to an intermediate point of the first column, drawing off a liquid enriched in oxygen from a bottom of the first column and/or drawing off a gas enriched in oxygen from the first column and drawing off a flow enriched in nitrogen from a top of the first column;
- (b) sending a flow enriched in argon from an intermediate point of the first column to a bottom of the second column and drawing off a flow rich in argon from a top of the second column;
- (c) compressing the flow enriched in nitrogen in a compressor and using the compressed flow to heat a bottom reboiler of the first column, producing an at least partially condensed flow enriched in nitrogen;
- (d) dividing the at least partially condensed flow enriched in nitrogen into first and second portions, sending the first portion to the top of the first column after an expansion step and sending the second portion to a top condenser of the second column after an expansion step in which the second portion is at least partially vaporized to form an auxiliary flow;
- and
- (e) expanding the auxiliary flow in a turbine wherein the auxiliary flow is at least partially liquefied and then sent to the top of the first column.
An apparatus for separating air by cryogenic distillation in a column system, the apparatus comprising:
- a first column operating at a first pressure and having a bottom reboiler and a second column operating at a second pressure having a top condenser, the first pressure being substantially equal to the second pressure;
- a compressor;
- a turbine;
- a first pipe configured to send air, which has been compressed, purified and cooled, to an intermediate point of the first column;
- a second pipe configured to withdraw a liquid enriched in oxygen from a bottom of the first column and/or a gas enriched in oxygen from the first column;
- a third pipe configured to withdraw a flow enriched in nitrogen from a top of the first column and then send said flow enriched in nitrogen to the compressor to form a compressed flow enriched in nitrogen;
- a fourth pipe configured to send a flow enriched in argon from an intermediate point of the first column to a bottom of the second column;
- a fifth pipe configured to withdraw a flow rich in argon from a top of the second column;
- a sixth pipe configured to send the flow enriched in nitrogen and compressed in the compressor to the bottom reboiler of the first column in order to produce an at least partially condensed flow enriched in nitrogen;
- a seventh pipe configured to send a first portion of the at least partially condensed flow enriched in nitrogen to the top of the first column after being expanded in an expansion step;
- an eighth pipe configured to send a second portion of the at least partially condensed flow enriched in nitrogen to the top condenser of the second column after being expanded in an expansion step in which the second portion is at least partially vaporized to form an auxillary flow;
- wherein the turbine is in fluid communication with the top condenser of the second column such that the turbine is configured to receive the auxillary flow from the second column and expand the auxillary flower to form an at least partially liquefied flow;
- and
- a ninth pipe configured to send the at least partially liquefied flow, or stream derived from the at least partially liquefied flow, to the top of the first column.
Dependencies are inferred from the claim text.