Air distillation apparatus and air distillation method

摘要

In an air distillation apparatus having a main heat exchanger 7 for cooling down feed air, a rectification column 9S comprising a rectifying portion 13 for separating the thus-cooled feed air to an oxygen-enriched component and a nitrogen component and a condenser 35S for partially condensing the latter, and a liquid nitrogen storage tank 31S for supplying liquid nitrogen by way of a supply valve V3, and a transport route 18 for transporting an oxygen-enriched liquid flowing down from said rectifying portion 13 to the bottom into said condenser 35S, the said oxygen-enriched liquid is not reserved at the bottom of the column. Control means include a liquid level detection means for detecting the height of a liquid level of said oxygen-enriched liquid reserved in said condenser 35S; and a control means LIC for controlling the opening degree of the supply valve V3, on the basis of the output therefrom, so that the liquid level of said oxygen-enriched liquid reserved in said condenser is kept almost at a set level.