Process for the cryogenic distillation of air

Apparatus for the production of pressurized GAN comprising:

• a cryogenic ASU comprising at least one distillation column, for producing LIN;
• pressurizing means for pressurizing LIN;
• conduit means for feeding LIN from the top of the column of the ASU producing said LIN to the pressurizing means;
• an auxiliary cryogenic distillation column comprising a main distillation zone for separating a fluid having an oxygen concentration at least equal to that of air into nitrogen-rich overhead vapor and oxygen-enriched bottoms liquid;
• transfer enabling means for enabling heat and optionally mass transfer between at least a portion of said nitrogen-rich overhead vapor and at least a portion of said pressurized LIN to produce nitrogen-rich liquid and pressurized GAN;
• conduit means for feeding pressurized LIN from the pressurizing means to the transfer enabling means;
• pressure reducing means for reducing the pressure of nitrogen-rich liquid to produce reduced pressure nitrogen-rich liquid;
• conduit means for feeding nitrogen-rich liquid from the auxiliary column to the pressure reducing means;
• and
• conduit means for feeding reduced pressure nitrogen rich liquid from said pressure reducing means to the ASU as reflux.