AIR LIQUEFACTION AND SEPARATION METHOD AND DEVICE

摘要

Disclosed is an air liquefaction separation method and apparatus by which the apparatus cost can be reduced when liquid products are collected, the method including: a feed air compression step in which the whole amount of a feed air is a pressurized feed air having a first set pressure which is higher than the operating pressure of the intermediate pressure column; an adsorption and purification step in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air; a combining step for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air; a cooling step in which a first branch air stream of the two divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, and a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for expansion; an expansion step in which the air for expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a low-temperature air; a step for introducing a part of the low-temperature air into the intermediate pressure column; a warming step in which the temperature of the remainder of the low-temperature air is recovered to obtain a returned air; a circulating compression step in which the returned air is pressurized to obtain the pressurized returned air; and a step for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.