| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-separating device that consumes less power and utilizes external cold. SOLUTION: A device is composed of a feed air supply unit, an air separation unit that consists of a high-pressure fractionating column 5 that has a recycle- gas delivery port 51 and an oxygen enriched air reboiler at the upper and bottom parts of the column, respectively, a low-pressure fractionating column 6 that has a low-pressure nitrogen gas delivery port 61 at the upper part of the column, and a first heat exchanger El that allows low-temperature gas and feed gas being discharged from the fractionating columns 5 and 6 to be subjected to heat exchange, and a cold supply unit that has a second heat exchanger E2 that boosts one part of the low-pressure nitrogen gas passing through the first heat exchanger E1 and allows a makeup compressor C1 for supplying to a recycle line, an outside chill source, and recycle gas to be subjected to heat exchange. Also, in the device, recycle gas returning paths P25 and P26 are provided, where the paths P25 and P26 supply the recycle gas passing through the chill supply unit to the upper part of the high-pressure fractionating column 5 via a reboiler E4 at the bottom of the high-pressure fractionating column 5.
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