Method and device for separating air by cryogenic distillation

A method for separating air by cryogenic distillation wherein, during a first run, a first flow rate of air is compressed in at least one compressor, cooled and separated in a system of columns, a first flow rate of a first distillation product is produced, high or medium voltage electricity requirements of the compressor or compressors of the method are met from an electricity grid, during a second run, a second flow rate of air lower than the first flow rate of air is compressed in the at least one compressor, the second flow rate is cooled and separated in the system of columns, a second flow rate of a first distillation product is produced from the system of columns, lower than the first flow rate of the first product, high or medium voltage electricity requirements of the compressor being lower than during the first run and, during an intermediate run taking place after the first run and before the second run, the consumption of electricity from the electricity grid of the compressor or compressors is lower than that during the first run and greater than or equal to that during the second run, characterized in that during the intermediate run, at least part of the electricity requirements of the method operating during the intermediate run is met from at least one electrochemical accumulator.

A device for separating air by cryogenic distillation comprising at least one compressor for compressing air, a means for cooling and purifying the compressed air, a system of columns comprising at least one air distillation column for separating air into oxygen and nitrogen, a motor for driving at least one of the at least one compressors, a means for supplying the motor with high and/or medium voltage electricity coming from a grid, at least one electrochemical accumulator, a means for supplying the motor with high and/or medium voltage electricity coming from the at least one accumulator, a means for interrupting the supply of electricity to the motor from the grid and a means for interrupting the supply of electricity to the motor from the at least one accumulator, the means for interrupting the supply of electricity being controlled from a control system, a means for sending a first flow rate of air to be compressed in the at least one compressor during a first run, a means for sending a second flow rate of air lower than the first flow rate of air to be compressed in the at least one compressor during a second run, a means for connecting the at least one accumulator to the motor during an intermediate run taking place after the first run and before the second run in response to a load shed request signal.