| 摘要 |
<p>Purified air typically at its dew point is passed into distillation column 10 through inlet 2. Oxygen-rich liquid is withdrawn through outlet 6 and is passed to the top of a mixing column 20. Nitrogen-rich vapour passes from the top of the distillation column 10 to the bottom of the mixing column 20. In the mixing column, there is a downward flow of liquid that becomes progressively richer in nitrogen and an upward flow of vapour that becomes progressively richer in oxygen. Liquid nitrogen is withdrawn from the mixing column 20 through outlet 16 and is returned to the distillation column 10 to provide reflux for the distillation column 10. In addition a mixed stream 28 comprising oxygen and nitrogen is withdrawn from the column 20 as product or waste. The mixing column 20 is provided with a first condenser 30 at its top and a second condenser 40 which takes a vapour stream from intermediate the outlet 28 and the top of the column 20 and returns liquid to the column 20. The second condensation is effected by heat exchange with boiling liquid taken from and returned to the column 10. An argon-enriched oxygen stream is withdrawn (in 4) from the column 10 and is separated in a second distillation column 50 to yield an argon product.</p> |
