| 摘要 |
<p>Air is separated into oxygen and nitrogen in a double rectification column 10 comprising a higher pressure rectification column 4 and a lower pressure rectification column 6. Liquid nitrogen reflux for the separation is provided by condensing nitrogen vapour taken from the column 4 in a condenser-reboiler 8. Additional separation is performed in an intermediate pressure rectification column 24. A first stream of argon-enriched vapour is withdrawn from an intermediate region of the lower pressure rectification column 6 and has an argon fraction separated from it in a first side rectification column 52. A second stream of argon-enriched vapour is similarly withdrawn and is separated in a second side rectification column 81 which provides vapour to heat a reboiler 22 associated with the intermediate pressure rectification column. Alternatively a stream of oxygen vapour can be so employed instead of the second argon-enriched vapour stream. <IMAGE></p> |
