초록 ▼

A first stream of cooled and purified air is introduced into a higher pressure rectification column 12 through an inlet 14 and is separated into oxygen-enriched liquid and nitrogen vapour. A stream of the oxygen-enriched liquid is flashed through a pressure reducing valve 40 into an intermediate rec

A first stream of cooled and purified air is introduced into a higher pressure rectification column 12 through an inlet 14 and is separated into oxygen-enriched liquid and nitrogen vapour. A stream of the oxygen-enriched liquid is flashed through a pressure reducing valve 40 into an intermediate rectification column 22 in which it is separated into further-enriched liquid and an intermediate nitrogen vapour. A stream of the further-enriched liquid is reboiled in condenser-reboiler 46 and is introduced into a lower pressure rectifier 34 comprising an upper stage 58 and a lower stage 60. The lower pressure rectifier 34 has a bottom condenser-reboiler 16 which is heated by a second stream of cooled and purified air. The second stream is itself condensed in the reboiler 16 and is introduced into the higher pressure column 12. The lower pressure rectifier also has an intermediate condenser-reboiler 22 which is employed to form liquid nitrogen reflux for the rectification by condensing nitrogen vapour separated in the higher pressure rectification column. In alternative examples of the process, the liquid that is flashed through the valve 40 is subjected to phase separation rather than rectification.

대표청구항 ▼

A method of separating air, comprising the steps of: a) separating pre-cooled and purified air in a higher pressure rectifier into oxygen-enriched liquid and nitrogen vapour; b) separating a stream of the oxygen-enriched liquid at a pressure between the pressure at the top of the higher pressure rec

A method of separating air, comprising the steps of: a) separating pre-cooled and purified air in a higher pressure rectifier into oxygen-enriched liquid and nitrogen vapour; b) separating a stream of the oxygen-enriched liquid at a pressure between the pressure at the top of the higher pressure rectifier and that at the bottom of a lower pressure rectifier so as to form a liquid further enriched in oxygen and an intermediate vapour; c) separating a stream of the further-enriched liquid in the lower pressure rectifier into oxygen and nitrogen; and d) providing liquid nitrogen reflux for the higher and lower pressure rectifiers, part of the liquid nitrogen reflux being formed by condensing a stream of said nitrogen vapour by indirect heat exchange with liquid from an intermediate mass transfer region of the lower pressure rectifier.