Cryogenic recovery of argon from air

摘要

Argon-enriched mixture from air fractionation is fed into the raw argon column, from which a raw argon fraction is fed into the pure argon column. An argon product is taken low down, and a nitrogen fraction is taken from high up, in this column. A novel aspect is increased pressure of the nitrogen fraction downstream of the extraction point. An Independent claim is included for the equipment carrying out the process described. Preferred features: At least some of the nitrogen fraction downstream of the pressure increase, is released into the atmosphere or is used downstream or upstream of the pressure increase, as refrigerant gas for a unit purifying air employed in the rectification system. At least part of the nitrogen fraction downstream of the pressure increase is led off as a nitrogen product. That part of the nitrogen fraction taken as product, is admixed downstream of the pressure increase to a further nitrogen product fraction. Liquid nitrogen, which does not arise from the condensation of a gas taken from the pure argon column, is introduced into the upper region of the pure argon column.