Method for operating an air separation plant, having a distillation column system, a heat exchanger and an adsorber, and air separation plant

A method for operating an air separation plant which comprises a distillation column system, a heat exchanger, and an adsorber, wherein the process comprises:

• in a first time period, a first operating mode is carried out and, in a second time period following the first time period, a second operating mode is carried out, the first and second time periods being carried out multiple times alternately,
• in the first operating mode, compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger,
• in the first operating mode, an air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger,
• in the first operating mode, a first end of the heat exchanger is brought to a first temperature level and a second end of the heat exchanger is brought to a second temperature level below the first temperature level,
• in the second operating mode, the cooling of the compressed air and the heating of the air product in the heat exchanger are partially or completely suspended, and
• in the second operating mode, the temperature of the second end of the heat exchanger increases from the second temperature level to a third temperature level above the second temperature level,
• wherein
• in a third time period between the second time period and the first time period, a third operating mode is carried out,
• in the third operating mode, compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger,
• in the third operating mode, the air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger, and
• in the third operating mode, an adjustable portion of the compressed air cooled in the heat exchanger or an adjustable amount of additional compressed air, which is at least partially freed of water and carbon dioxide in the adsorber but is not cooled in the heat exchanger, is fed to the air product to form a combined stream before the air product is heated in the heat exchanger.