The principle of distillation column of air separation unit is to separate oxygen and nitrogen components into required purity by using different boiling points of oxygen and nitrogen components in air. The column of distillation column is cylindrical, with regular packing in the column and liquid collecting distributor in the column. In the distillation process, the low boiling point gradually evaporates, the high boiling point gradually liquefies, and the pure nitrogen with low boiling point is obtained at the top of the column.
