The purified air is separated into two parts:one part enters the main heat exchanger,

then it is cooled by expanded hypothermal air. The other part is cooled to some temperature in the high-pressure Vaporizer of LOX .Two parts of air mixed in the main heat exchanger.

It is cooled furtherly then reaches to some degree of moisture before it enters oxygen distillation column.The air becomes into liquefied air in oxygen column.Through subcooler and throttling valve,the liquefied air of the bottom of oxygen column enters the condenser inside the top of oxygen column.As reflux,oxygen enriched gas air vaporized by condenser is drawn out of the top of oxygen column and reheated to a temperature of ***1ºC within the main heat exchanger through liquefied air subcooler.The most part enters expansion turbine for expansion and refrigeration.The expanded oxygen enriched gas air comes back to cold part of the main heat exchanger.It is reheated to a temperature of about *3 ºC in the main heat exchanger and then drawn out of the cold box. It is also used as regenerated air of Molecular sieve adsorption unit.