AIR SEPARATOR

PROBLEM TO BE SOLVED: To enable efficient operation without the generation of flushing by arranging a refrigerator for chilling as a cold source for air liquefying inside the tower of a rectifying tower. SOLUTION: Compressed air sent to the inside of a heat exchanger 1 is cooled by exhaust N, gas passing through a discharging pipe 32 and the product N2 gas sent to the inside of it from the gas taking out pipe 30. From the circumferential wall at the under part of a rectifying tower 2 to the lid body closing the upper edge opening of a cylinder body 2a, a pulse tube refrigerator 3 with the coolant of He for liquefying the air is installed. The cold source inside the rectifying tower 2 is generated by it, the compressed air sent to the rectifying tower 2 through a compressed air introducing pipe 24 is cooled by it, the part of the compressed air is liquefied to be collected at the bottom as the liquid air and the N2 gas is collected at the upper part with the state of gas. As the expansion turbine is not used for forming cold source, the follow up operation against the fluctuation of the load is easier and the possibility of failure is decreased.