In order to ensure the stable operation of the distillation column, the in and out material and its state of the distillation column needs to meet the material balance, component balance and energy balance. The main cooling liquid oxygen surface is an important indicator of whether the cooling capacity of the air separation plant is balanced or not. When the cooling loss of the unit is greater than the cooling capacity, the moisture content of the air entering and leaving the column (the liquid content in the saturated air) will be reduced, and the nitrogen to be condensate in main cooling needs to be condensed, the evaporation of liquid oxygen will also increase, and the surface of liquid oxygen will decrease. On the contrary, when the cooling capacity is greater than the cooling loss of the unit, the moisture content of the air entering the lower column will increase, and the amount of nitrogen to be condensed in the main cooling system will decrease, and the liquid oxygen surface will naturally increase.
