| 摘要 |
PROBLEM TO BE SOLVED: To apply to an air separation due to a low-temperature distillation by adding an unrefined argon column by utilizing a three-column process, separating a low purity oxygen and separating it into a high purity oxygen and an argon by-product. SOLUTION: A part 9 of first nitrogen-enriched gas from a high-pressure column 101 is supplied to a bottom reboiler 11 of an intermediate-pressure column 102, condensed, then return to the column 101 as a reflux, and a part of a second oxygen-enriched flow 20 is expanded, then sent to a low-pressure column 103, the residue is sent to a top condenser 13 of the column 102, vaporized, and then supplied to the column 103. The supplied gas of the column 103 is separated into a third oxygen-enriched flow 31 and a third nitrogen- enriched flow at its top. Further, an unrefined argon column 104 is added, a third oxygen flow 31 of the liquid of a low purity is separated, and separated into a high purity oxygen and an argon by-product.
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