Low temperature air fractionation accommodating variable oxygen demand

Abstract

For the low temperature fractionation of air with variable oxygen production, compressed, prepurified, and cooled air (conduit 5) is initially fractionated in the high pressure stage 10 of a two-stage rectification 9. The thus-produced bottom liquid is further separated in the low pressure stage 11. Liquid nitrogen 14 from the high pressure stage 10 and liquid oxygen from the low pressure stage 11 can be stored intermediarily in tanks 35 and 32. An enriched liquid air tank 40 is additionally provided in order to store bottom liquid 12 from the high pressure stage 10. In case of increased oxygen production, the internal rate of flow in the high pressure stage 10 can be raised; and simultaneously the internal rate of flow in the low pressure stage 11 and the reflux ratios in both rectifying stages 10, 11 can be maintained constant. The constant reflux ratio in the low pressure column permits the argon bubble concentration to remain high, permitting a substantially maximum rate of separation of the argon in a crude argon column.

Dependencies are inferred from the claim text.