| 摘要 |
In a second way of operating, the turbine (D3) is fed with an air flow at a pressure below the first pressure and produces air at a lower pressure than the second pressure. All or part of the air expanded in the turbine is sent to one of the columns (K2) operating at a lower pressure than the high pressure column and/or atmosphere. Air separation in an apparatus containing at least two columns, with a high pressure column (K1) and a low pressure column (K2), in which during a first way of operating, between 50 and 90% of the air (7) is sent to the high pressure column and between 10 and 50% of the air (5) is suppressed in a suppressor. The suppressed air is divided into at least two fractions (6, 9): the first fraction exchanges heat with at least one liquid flow (37) from one of the columns and a second fraction is expanded in a turbine (D3) from a first pressure to a second pressure and the expanded fraction is sent at least in part to the high pressure column. The liquid flow from one of the columns is vaporized by the heat exchange to form a first oxygen-rich and/or nitrogen-rich and/or argon-rich gas flow as the final product. The heat exchange between the first fraction of air and the liquid is indirect, or is direct in a mixing column. The second fraction of air is not sent to a suppressor coupled to a motor but to a suppressor linked to the turbine which takes air at a pressure below the first pressure in the first way of operating. During the first way of operating, an oxygen-rich liquid flow is extracted from the low pressure column and vaporized by heat exchange. An oxygen-rich gas flow is extracted from the low pressure column and heated in an exchange line (E1) where it cools the feed air and at least one nitrogen-rich gas flow is extracted from the low pressure column and heated in the exchange line. During the second way of operating, the liquid flow is reduced eventually to zero, the oxygen-rich gas flow increases and the nitrogen-rich gas flow continues to be extracted and heated. An Independent claim is also included for an installation for carrying out the above process, including means of sending air to the heat exchange line and to the turbine without passing through the suppressor.
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