METHOD AND DEVICE FOR OBTAINING PRESSURIZED NITROGEN AND PRESSURIZED OXYGEN BY LOW-TEMPERATURE SEPARATION OF AIR

摘要

The invention relates to a method and device for obtaining pressurized nitrogen and pressurized oxygen by low-temperature separation of air. Compressed and purified feed air is cooled down in a main heat exchanger and introduced into a distillation column system comprising at least one high-pressure column and one low-pressure column. The distillation column system for nitrogen-oxygen separation in addition contains a residual gas column operating at a pressure which is lower than the operating pressure of the low-pressure column. A liquid crude oxygen fraction from the high-pressure column (50) is expanded and passed to the residual gas column at a first intermediate point. A gaseous impure nitrogen stream from the low-pressure column is introduced into a bottoms evaporator of the residual gas column and there is at least partly liquefied. The at least partly liquefied impure nitrogen stream is expanded and introduced into the upper region of the residual gas column.