With the rapid development of industry, nitrogen has been widely used in chemical industry, electronics, metallurgy, food, machinery and other fields, and the demand for nitrogen in China has increased at a rate of more than 8% per year, and the PSA nitrogen machine has been widely used.

PSA nitrogen machine: PSA Chinese meaning: pressure swing adsorption. The principle is to use molecular sieve to different gas molecules "adsorption" performance differences and separate the gas mixture, it is air as a raw material, the use of a high-efficiency, highly selective solid adsorbent for nitrogen and oxygen selective adsorption performance to separate the nitrogen and oxygen in the air.

At present, carbon molecular sieve and zeolite molecular sieve are used more in the field of nitrogen and oxygen production. The separation of oxygen and nitrogen by molecular sieve is mainly based on the different diffusion rates of the two gases on the molecular sieve surface. Carbon molecular sieve is a carbon-based adsorbent with some characteristics of activated carbon and molecular sieve. Carbon molecular sieves are composed of very small pores with pore sizes ranging from 0.3nm to 1nm. The smaller diameter gas (oxygen) diffuses faster and enters the molecular sieve solid phase more, so that nitrogen can be enriched in the gas phase. After a period of time, the adsorption of oxygen by the molecular sieve reaches equilibrium. According to the characteristics of the adsorption amount of adsorbed gas by the carbon molecular sieve under different pressures, the pressure is reduced to remove the adsorption of oxygen by the carbon molecular sieve, which is called regeneration. The pressure swing adsorption method usually uses two towers in parallel, alternating pressure adsorption and decompression regeneration, so as to obtain a continuous flow of nitrogen.