With the rapid development of industry, nitrogen has been widely used in chemical engineering, electronics, metallurgy, food, machinery and other fields. The demand for nitrogen in our country increases at a speed of more than 8% every year. The chemical property of nitrogen is not active, and it shows great inertia under normal conditions, 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.
Generally, the purity of protective gas is required to be 99.99%, and some require high purity nitrogen of more than 99.998%. Liquid nitrogen is a relatively convenient cold source, which is more and more widely used in food industry, medical service and the seminal storage of animal husbandry. During the production of synthetic ammonia in the chemical fertilizer industry, if the mixture of hydrogen and nitrogen, the feed gas of synthetic ammonia, is washed and refined by pure liquid nitrogen, the content of lazy gas can be extremely small, the content of nitrous oxide and oxygen should not exceed 20ppm.
