| 摘要 |
An air separation method in which a liquid air stream, produced by vaporizing a pumped liquid oxygen stream, is introduced into a lower pressure column and optionally, a higher pressure column of an air separation unit. The liquid air stream is subcooled by extracting a main air feed to the higher pressure column from a main heat exchanger at a temperature warmer than the liquid air stream to increase argon recovery in an argon column connected to the lower pressure column. This temperature is selected such that the liquid air stream approaches an average temperature of the return streams being fed into the main heat exchanger from the higher and lower pressure columns at a range between about 0.2K and about 3K.
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