| 摘要 |
PROBLEM TO BE SOLVED: To provide equipment for producing high purity nitrogen by increase of gas separation efficiency and a method therefor, by solving the following problem: when nitrogen is produced from air, it is more difficult for a membrane separation method to produce high purity nitrogen as compared with other separation methods. SOLUTION: At least two membrane separation apparatuses are used. Permeated gas leaving the latter membrane separation apparatus is recycled to supply gas for the former membrane separation apparatus, and the amount of non-permeated gas drawn from the former membrane separation apparatus, that is, the amount of supply gas for the latter membrane separation apparatus is controlled so that oxygen concentration in non-permeated gas discharged from the former membrane separation apparatus is confined to a set value, whereby high purity nitrogen can be produced. COPYRIGHT: (C)2011,JPO&INPIT
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