Methods for low-temperature air separation and applicable distillation column systems

By arranging high-pressure and low-pressure towers side-by-side in a cryogenic air separation unit, optimizing stream heat exchange, and using a subcooler, the problem of increased costs due to liquid pumps is solved, achieving efficient nitrogen extraction and ease of use.

CN122083620APending Publication Date: 2026-05-26LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE
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Patent Information

Application Number
CN202411707031.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-11-26
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

In the existing technology, the cryogenic air separation device with two towers arranged side by side requires the use of liquid pumps, which increases equipment investment and maintenance costs, while the nitrogen extraction rate is not optimized.

Method used

The high-pressure tower and low-pressure tower are arranged side by side. The first condenser-evaporator is set at the bottom of the low-pressure tower and the second condenser-evaporator is set at the top of the low-pressure tower. A gas-liquid separator and a liquid nitrogen pump are used to return the liquid. Combined with a subcooler, the heat exchange of the stream is optimized, the number of liquid pumps is reduced and the nitrogen extraction rate is improved.

Benefits of technology

It reduced equipment investment costs, improved nitrogen extraction rate, reduced flash vapor volume, and enhanced the ease of transportation and installation of the equipment.

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Abstract

This invention discloses a method for cryogenic air separation and a suitable distillation column system. A high-pressure column and a low-pressure column are arranged side-by-side, with a first condenser-evaporator located at the bottom of the low-pressure column and a second condenser-evaporator located at the top. Oxygen-enriched stream from the bottom of the high-pressure column is fed into the low-pressure column for further distillation. The high-pressure liquid nitrogen generated by the first condenser-evaporator is depressurized and separated into gas and liquid phases in a gas-liquid separator. The liquid phase is then combined with the low-pressure liquid nitrogen generated by the second condenser-evaporator, pressurized by a liquid nitrogen pump, and fed into the high-pressure column as reflux liquid. The gaseous product in the gas-liquid separator is combined with the flash gas at the outlet of the liquid nitrogen pump and returned to the low-pressure column.
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Citation Information

Patent Citations

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    CN212006434U

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    US4222756A

  • Double column multiple condenser-reboiler high pressure nitrogen process

    US4453957A

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    US4717410A