The condenser evaporator is the link between the upper column and the lower column, which is used to heat exchange the liquid oxygen returned from the bottom of the upper column and the rising gas and nitrogen at the top of the upper column. If the heat transfer surface of the condenser is insufficient, the heat load will be reduced, the evaporation of liquid oxygen will be reduced, and the condensation of gas and nitrogen will be reduced accordingly. Therefore, he will directly affect the distillation condition of the upper and lower column. At the same time, the intake of the lower column will be reduced, the air can not be fed, and the oxygen output will naturally decrease.