The invention relates to 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, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.

The invention relates to 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, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.

A system and method serve generate oxygen by low-temperature air separation in a distillation column system having a high-pressure column and a low-pressure column, a main condenser which is constructed as a condenser-evaporator, and an auxiliary column. A gaseous oxygen-containing fraction is introduced into the auxiliary column. A nitrogen-containing liquid stream from the high-pressure column, the main condenser or the low-pressure column is applied as reflux to the top of the auxiliary column. An argon-rich stream from an intermediate site of the low-pressure column is introduced into an argon removal column that has an argon removal column top condenser. The low-pressure column is arranged beside the high-pressure column, the main condenser is arranged over the high-pressure column, the auxiliary column is arranged over the main condenser, the argon removal column is arranged over the auxiliary column and the argon removal column top condenser is arranged over the argon removal column.