| 摘要 |
An air separation method and apparatus in which a stream of air is compressed in a compressor and purified in a unit. One stream of the resulting air is cooled in a heat exchanger and is separated in an arrangement of rectification columns comprising a higher pressure rectification column, a lower pressure rectification column, and a further rectification column for separating argon from an argon-enriched oxygen stream withdrawn from the lower pressure rectification column and the stream of resulting air is introduced into the higher pressure rectification column through an inlet. A second cooled, compressed, purified air stream is expanded in an expansion turbine and is introduced into the lower pressure rectification column. A third cooled, compressed, purified air stream is expanded in a second expansion turbine and is introduced into the higher pressure rectification column. A fourth compressed, purified air stream is expanded in a third expansion turbine having an outlet temperature higher than those of the other two turbines and is further cooled in the heat exchanger and is introduced into the higher pressure rectification column. The arrangement of turbines enhances argon recovery when liquid nitrogen product is produced.
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