Air separation equipment in the distillation is the use of two substances with different boiling points, many times for the process of partial condensation of mixed vapour and partial evaporation of mixed liquids, in order to achieve the purpose of separation.
Oxygen and nitrogen separation is the distillation process, oxygen and nitrogen two boiling points of different substances composed of mixed liquids, in the absorption of heat and partial evaporation, volatile components of nitrogen will be more evaporation; and mixed vapour in the release of heat and part of the condensation, difficult to volatile components of oxygen will be more condensation. If the higher temperature saturated vapour is in contact with the lower temperature saturated liquid, the vapour will give off heat to the saturated liquid. The vapour will partially condense as it gives off heat and the liquid will absorb heat and partially evaporate. When the vapour partially condenses, the concentration of the low-boiling component (nitrogen) in the vapour increases because more oxygen condenses. The concentration of the high boiling point component (oxygen) in the liquid increases during partial evaporation because more nitrogen is evaporated. If, after a partial evaporation and partial condensation, the vapour with a higher nitrogen concentration and the liquid with a higher oxygen concentration come into contact with the liquid and the vapour at different temperatures, respectively, and partial condensation and partial evaporation occur again, the concentration of nitrogen in the vapour and the concentration of oxygen in the liquid will be further increased.
This process is carried out many times, the nitrogen concentration in the vapour is getting higher and higher, the oxygen concentration in the liquid is getting higher and higher, and finally the separation of oxygen and nitrogen is achieved.
