Method for operating at least one air separation apparatus and oxygen consumption unit

A process for operating a plant comprising at least two air separation units, a storage system, and an oxygen-rich gas consumer comprising a carbon fuel combustion unit or a gasification unit, the consumer being capable of generating electricity at least in a first operating phase, in which process the plant operates in a plurality of operating phases:

• a) in the first operating phase, during which the cost of the electricity is above a first price threshold, the consumer receives an amount of oxygen-rich gas above a first consumption threshold, coming from at least one of the air separation units, and the oxygen-rich gas consists partly of oxygen stored in the storage system, which is supplied by the air separation units during a second operating phase, and partly by oxygen produced by distillation in at least one air separation unit during the first operating phase;
• and
• b) in the second operating phase, during which the cost of the electricity is below a second price threshold, the second price threshold being below the first price threshold, the consumer consumes an amount of oxygen-rich gas below a second consumption threshold, the second threshold being below the first threshold, air is separated in at least certain of the air separation units, and an oxygen-rich liquid is sent from the separation unit or from the at least one separation unit to the storage system;
• and
• c) the number of separation units in operation during the first operating phase is fewer than the number of units that are in operation during the second operating phase.