The rectifying column of air separation equipment is the core device of cryogenic air separation. Its core function is to realize the efficient separation and purification of air components through multi-stage gas-liquid contact by utilizing the boiling point difference of oxygen, nitrogen, argon and other components, so as to provide high-purity gas products for industrial production.
Its core functions mainly include three aspects: first, separation and purification, by virtue of boiling point difference of components, through countercurrent contact of gas and liquid, mass transfer and heat transfer, high purity nitrogen is obtained at the top of the column, high purity oxygen is obtained at the bottom of the column, and argon fraction can be extracted from the side line; The second is efficient gas-liquid contact, which provides phase interface through tray or packing to ensure full gas-liquid contact without entrainment and improve separation efficiency; The third is cooling capacity circulation and impurities removal. The cooling capacity circulation is realized by cooperating with the condensing evaporator. Meanwhile, impurities such as carbon dioxide and water are removed to ensure product purity.
The rectifying column can be divided into plate column and packed column according to the gas-liquid contact mode. The plate column has large operation flexibility and is applicable to large high-pressure air separation; The packed column pressure is reduced, suitable for low-pressure high-purity separation. It can be divided into single stage and double stages according to the rectification stage. The double stage (double column) consists of high pressure lower column and low pressure upper column. It is a standard configuration for modern air separation, and can obtain high purity oxygen and nitrogen efficiently. In addition, it can be divided into main rectification column, argon column system and rare gas column according to functions, corresponding to main separation, argon purification and rare gas extraction respectively.
