| 摘要 |
PROBLEM TO BE SOLVED: To reduce the energy demand, and operate the system selectively with the liquefied nitrogen from the high-pressure column or the liquefied nitrogen tank of an air separating and rectifying facility. SOLUTION: Ultrahigh purity nitrogen is manufactured, making use of a low- temperature separation technique. High-pressure nitrogen components 1 not containing oxygen, taken out of the upper region of the high-pressure column within an air rectifying facility, or liquefied nitrogen not containing oxygen, taken out of a liquefied nitrogen tank 22, is led in a column bottom heating system of low-pressure column 2 and is depressurized. Hereby, liquefied nitrogen evaporates within the low-pressure column 2, and gas is extracted as column head gas 5 not containing carbon dioxides is extracted at the column head of the low-pressure column 2 while removing the carbon dioxides by the contact with the reflux containing ultrahigh purity nitrogen being loaded in the column head of the low-pressure column 2, by raising the steam arising at that time within the low-pressure column 2, and this column head gas is liquefied at least partially after being boosted 9, and this liquefied partial flow is led in a column head heating system of He-Ne-H2 column 4, and is depressurized, and ultrahigh-purity nitrogen 19 is taken out of the He-Ne-H2 column 4 in liquid condition.
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