Method 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
In a method for separating air by cryogenic distillation in a system of columns comprising a first column operating at a first pressure and a second column operating at a second pressure which is lower than the first column, the temperature T1 at which an airflow leaves, after cooling, the heat exchanger by rising towards the cold end of said heat exchanger and enters the first column is at least 1° C., preferably at least 2° C., higher than the dew point of the airflow.
Claims15
1-14. (canceled)
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 lower than the first pressure, the top of the first column being thermally coupled to the bottom of the second column, in which:
- i) cooling an air flow that has been purified of water and carbon dioxide in a heat exchanger and then sending said air flow to the first column in gaseous form;
- ii) withdrawing an oxygen-enriched liquid from the bottom of the first column, subcooling the oxygen-enriched liquid in a subcooler, and then sending said oxygen-enriched liquid to the second column;
- iii) withdrawing a nitrogen-enriched liquid from the upper part of the first column, subcooling the nitrogen-enriched liquid in a subcooler, and then sending said nitrogen-enriched liquid to the second column;
- iv) withdrawing a nitrogen-rich gas and an oxygen-rich fluid from the second column and then heating in the heat exchanger;
- wherein the heat exchanger is positioned below the first column, which in turn is positioned below the second column,
- wherein the air flow cooling in the heat exchanger traversing the heat exchanger from bottom to top,
- wherein the temperature T1 at which the air flow leaves the heat exchanger and enters the first column is at least 1° C. higher than the dew point of the air flow.
Dependencies are inferred from the claim text.