The separation process ensures a high purity product and a good yield.Air distillation consists of gas-liquid exchange of oxygen and nitrogen, where the liquid meets the rising O2-N2 mixture in a countercurrent.Therefore, distillation trays (e.g. porous trays) are mainly used for such exchange.Due to the low boiling point of nitrogen, when equilibrium is reached, the concentration of N2 in the vapor directly above the liquid mixture (liquid air) is higher than that in the liquid.Steam and liquid distillates pass through distillation trays in an attempt to maintain equilibrium by exchanging oxygen and nitrogen during contact: this process also includes heat exchange (condensation of oxygen, vaporization of nitrogen).As a result, the nitrogen concentration of the rising gas mixture becomes higher and higher, and the oxygen concentration in the falling liquid becomes higher and higher.
