Liquid nitrogen systems are widely used in various industries

Nitrogen has a wide range of uses in the chemical industry, petroleum industry, electronics industry, metal smelting and processing industries.
1. Application in chemical industry: Nitrogen is the main raw material for ammonia synthesis. The nitrogen required for ammonia synthesis does not need to be separated and purified, and is directly derived from air. In the production process of ammonia synthesis gas, the oxygen in the air undergoes a high-temperature catalytic reaction with hydrocarbon raw materials, and after conversion, decarburization, methanation and other processes, a mixed gas containing a small amount of methane, a trace of carbon monoxide and carbon dioxide, mainly hydrogen is generated The nitrogen and argon in the air do not participate in the reaction and directly enter the synthesis gas, thereby obtaining ammonia synthesis gas mainly composed of hydrogen and nitrogen. Using liquid nitrogen scrubbing process to purify the synthesis gas can prolong the service life of the catalyst and improve the ammonia synthesis efficiency.
Nitrogen is also the main source of synthetic calcium cyanamide, sodium cyanide and silicon nitride.
The liquid nitrogen system can be used as an auxiliary gas for the production of polyethylene. For example, a polyethylene production line with an annual output of 10 million tons needs to provide 4,400 standard cubic meters of pure nitrogen per hour.
The liquid nitrogen system uses the chemical inactivity of nitrogen to fill many reactors and storage tanks of flammable liquid substances with nitrogen, which not only protects materials from oxidation, maintains product quality, but also ensures safety and prevents combustion accidents.
2. Application in petroleum natural gas and coal mining industry: filling nitrogen in an oil well can not only increase the pressure in the well and increase the oil production volume, but also can be used as a cushion in the measurement of drill pipe, completely avoiding mud paddle The possibility of pressure squeezing the lower test tube column. In addition, nitrogen is also used in downhole operations such as acidification, fracturing, hydraulic orifices, and hydraulic packer setting. The liquid nitrogen system is filled with nitrogen in natural gas to reduce the heating value. When replacing crude oil pipelines, liquid nitrogen can be used to inject the materials at both ends to solidify and block them. The liquid nitrogen system uses nitrogen for the pressure transport of pulverized coal, which is safe, convenient and economical.
3. Application in the electronics industry: In the electronics industry, the silicon wafer is purged with dry nitrogen to keep the silicon wafer dry and clean. In the production process of large-scale integrated circuits, high-purity nitrogen can be used as the carrier gas, inert protective gas and packaging gas of the chemical reaction gas.
4. Application in metallurgy industry: Nitrogen is mainly used as protective gas and purge gas in metallurgical industry. During the heat treatment of steel rolling and metal, due to the preservation and expansion of nitrogen, the high temperature oxidation of the metal is reduced and the surface is smooth. Filling the non-ferrous metal smelting furnace with nitrogen can reduce the amount of oxygen and temperature, reduce oxidation, and improve product purity. Purge the molten steel with nitrogen to reduce the hydrogen content in the steel and increase the strength of the product. Blowing in 86% of nitrogen when the blast furnace is started can reduce coke consumption and extend service life. Nitrogen is filled in the plasma arc furnace to produce nitrided high-speed tool steel.
5. Application in mechanical processing: Liquid nitrogen is used for excessive or static metal assembly, which avoids high temperature oxidation and can maintain the surface finish of the parts. Parts processed with liquid nitrogen bubbles can prolong the wear life. The use of liquid nitrogen cooling in metal cutting has the advantages of long life and high surface finish.
6. Application of science and technology: High purity nitrogen is a commonly used carrier gas in gas chromatography analysis. Liquid nitrogen is an important cold source in scientific instruments or scientific experiments. For example, the single crystal lithium detector of the EDAX energy spectrometer needs to be stored and used at the temperature of liquid nitrogen. Many tests are conducted at low temperature, and the cooling capacity is provided by liquid nitrogen in most cases. Liquid nitrogen can be used as a cold source for various cold traps, cold pumps and low-temperature superconductors.