With the rapid development of industry, nitrogen has been widely used in chemical industry, electronics, metallurgy, Bai food, machinery and other fields. The demand of nitrogen in China increases by more than 8% every year. The chemical property of nitrogen is not active, and it is very inert in ordinary state, so it is not easy to react with other substances. Therefore, nitrogen is widely used as protective gas and sealing gas in metallurgical industry, electronic industry and chemical industry. The purity of protective gas is 99.99%, and some require high-purity nitrogen above 99.998%. Liquid nitrogen is a convenient cold source, and it is more and more widely used in semen storage in food industry, medical industry and animal husbandry. In the production of synthetic ammonia in chemical fertilizer industry, if the mixture of hydrogen and nitrogen is washed and refined with pure liquid nitrogen, the content of inert gas will be very small, and the content of sulfur monoxide and oxygen will not exceed 20ppm.
Pure nitrogen can not be directly absorbed from nature, and air separation method is mainly used. The air separation methods include cryogenic method, pressure swing adsorption method (PSA) and membrane separation method.
The conclusions are as follows
1. When the continuous load of nitrogen is more than 600 M3N / h, the intermittent load is not too large, and can be vaporized by liquid nitrogen to meet the requirements, cryogenic nitrogen production should be adopted.
2. When the continuous load of nitrogen is more than 600 M3N / h, the intermittent load is large, and the vaporization of liquid nitrogen can not satisfy the demand, the way of cryogenic nitrogen production and PSA intermittent gas supply can be adopted.
3. When the continuous load of nitrogen is less than 600 M3N / h, PSA can be used to produce nitrogen.
4. PSA nitrogen production is especially suitable for nitrogen load less than 3000 M3N / h, nitrogen purity of 95%, and intermittent operation conditions.
5. When the process unit needs liquid nitrogen, cryogenic nitrogen production should be adopted unless there is the possibility of external supply of liquid nitrogen.
Post time: Nov-23-2020