CRYOGENIC METHOD OF PRODUCING NITROGEN FROM AIR Russian patent published in 1996 - IPC

FIELD: cryogenic engineering; plants for separation of air by low-temperature rectification method. SUBSTANCE: compressed purified air is cooled and is divided into two parts; one part of air is introduced into high-pressure column for separation into first fractions enriched with nitrogen and oxygen, second part of air is condensed, evaporated and is fed to low-pressure column where it is separated into second fractions enriched with nitrogen and oxygen. Evaporation of part of condensed air is effected by indirect heat exchange with first fraction enriched with nitrogen; first fraction enriched with oxygen is directed to low-pressure column for separation. EFFECT: enhanced efficiency. 10 cl, 4 dwg, 1 tbl