Method for plant and separating air by cryogenic distillation
AssigneeL`Air Liquide, Societe Anonyme Pour L`Etude et L`Exploitation des Procedes Georges Claude
InventorsBenoit Davidian, Francois De Bussy
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Abstract
In a plant for separating air which does not comprise an argon column, an intermediate-pressure column (102) has a bottom reboiler (24) which is heated by a gas (233) coming from the low-pressure column (103). The intermediate-pressure column is fed from the high-pressure column (101). This makes it possible to reduce the energy consumption while improving the efficiency of the process.
Claims13
Process for separating air in a separation apparatus comprising a high-pressure column (101), an intermediate-pressure column (102) having a bottom reboiler (24) and a low-pressure column (103) in which
- a) at least one mixture (1) of at least oxygen, nitrogen and argon is sent at least to the high-pressure column where it is separated into a first oxygen-enriched stream and a first nitrogen-enriched stream,
- b) at least part of the first oxygen-enriched stream (10) is sent to the column operating at intermediate pressure where it is separated into a second oxygen-enriched stream (20) and a second nitrogen-enriched stream (25),
- c) at least part of the second oxygen-enriched stream and/or the second nitrogen-enriched stream is sent to the low-pressure column,
- d) a gas (233) is sent from the lower part of the low-pressure column to the bottom reboiler of the intermediate-pressure column where it is condensed at least partially before being sent back to the low-pressure column,
- e) at least one oxygen-enriched fluid (31) and at least one nitrogen-enriched fluid (72) are withdrawn from the low-pressure column and
- f) at least part of the first nitrogen-enriched fluid is condensed at least partially in a reboiler-condenser associated with the low-pressure column and at least part of the at least partially condensed fluid is sent back to the high-pressure column
- characterized in that no fluid containing between 3 and 20 mol % argon is enriched with argon in a column of the apparatus other than the high-pressure, low-pressure and intermediate-pressure columns.
Process according to one of the preceding claims in which one or more of the gaseous and/or liquid airstream(s) is (are) sent to the intermediate-pressure column and/or to the low-pressure column and/or to the high-pressure column.
Process according to one of the preceding claims in which the gas (233) coming from the lower part of the low-pressure column sent to the bottom reboiler contains between 1 and 20 mol % argon.
Process according to one of the preceding claims in which at least part of the second nitrogen-enriched stream is condensed, optionally in a top condenser (22) of the intermediate-pressure column.
Plant for separating air by cryogenic distillation comprising a high-pressure column (101), an intermediate-pressure column (102) having a bottom reboiler (24) and a low-pressure column (103), the high-pressure column and the low-pressure column being thermally connected together, means for sending a mixture (1) of at least oxygen, nitrogen and argon at least to the high-pressure column, means to send an oxygen-enriched stream (10) from the high-pressure column to the intermediate-pressure column, means to send an oxygen-enriched fluid (20) and/or a nitrogen-enriched fluid (25) from the intermediate-pressure column to the low-pressure column, means to send a fluid (233) from the low-pressure column to the bottom reboiler of the intermediate-pressure column, means to withdraw a nitrogen-enriched fluid (72) and an oxygen-enriched fluid (31) from the low-pressure column
- characterized in that it does not comprise means for the argon enrichment of a fluid containing between 3 and 20 mol % argon other than the high-pressure, low-pressure and intermediate-pressure columns.
Dependencies are inferred from the claim text.