There are three main methods of nitrogen production of air separation, namely cryogenic air separation, molecular sieve air separation (PSA) and membrane air separation. Cryogenic air separation is a traditional method for nitrogen production from air separation, which has a history of several decades. It takes air as raw material, after compression and purification, and then uses heat exchange to liquefy air into liquid air, and then uses different boiling points of liquid oxygen and liquid nitrogen to separate nitrogen by distillation. Nitrogen production of molecular sieve air separation is a method that uses pressure swing adsorption principle and carbon molecular sieve to selectively adsorb oxygen and nitrogen to separate nitrogen and oxygen, which is generally called PSA nitrogen production. Nitrogen production of membrane air separation is to separate oxygen and nitrogen by using gases with different properties such as oxygen and nitrogen with different permeation rates in the membrane under certain pressure.
