The technology of air separation unit has been very mature, easy to operate and automatic operation in the whole process, which can reduce the operation cost of air separation unit. With the rapid development of China's gas industry and the upgrading of metallurgy, petroleum, chemical industry, medicine and other industries, the demand for oxygen, nitrogen and argon products in all walks of life is increasing, and the purity requirements are also higher and higher, which promotes the continuous development of air separation unit field.