MANUFACTURE OF ULTRA-HIGH-PURITY NITROGEN GAS AND DEVICE THEREFOR

PROBLEM TO BE SOLVED: To provide a method for manufacturing ultra-high-purity nitrogen gas that can be effectively utilized with inexpensive facilities. SOLUTION: In a method for filing compressing feed air, cooling it to a low temperature, and then introducing it to a rectifying column 7, performing its subcooling liquefaction separation for manufacturing an ultra-high-purity nitrogen gas, and for filling one portion of the amount of cold required for the subcooling liquefaction separation is supplied from the outside of the subcooling liquefaction separation system with the cold energy of the high-purity liquid nitrogen, one portion of a reflux liquid (ultra-high-purity liquid nitrogen) being generated by a condenser 9 at the upper portion of the rectifying tower 7 and is stored at an ultra-high-purity liquid nitrogen tank 25, and then ultra- high-purity liquid nitrogen being stored in the ultra-high-purity liquid nitrogen tank 25 is vaporized on backup.