Air separation equipment is the separation of air, distillation, and final separation into oxygen, nitrogen and other useful gases. Its minimum working temperature is 77K. Until the end of the 19th century the air is still called "permanent gases", later it was found that in deep low temperature air can be liquefied, and because of oxygen, nitrogen, the boiling point is different, can isolate the oxygen from air liquide and nitrogen. The first commercial oxygen generator was made in 1903 and was originally used for gas welding and cutting of metals. In the late 1930s, nitrogen fertilizer was needed for nitrogen, and oxygen was developed to produce oxygen and nitrogen at the same time, which was called air separation equipment.
To 50 s, due to oxygen steelmaking and application of the blast furnace blower process and nitrogen fertilizer industry, the rapid development of air separation equipment to the large-scale development, and the application of modern scientific research achievements, such as using turbine compressor, turbine expander, plate-fin heat exchanger, micro computer and molecular sieve adsorber and other equipment, air separation equipment constantly improve and perfect, the air pressure from the high voltage (20 million mpa) to low (less than 1 million mpa), the power consumption of per unit product also gradually decline (per cubic meter of oxygen consumption from 1.5 to 0.6 kw · h). Modern air separation equipment can produce all kinds of capacity, different purity of gas or liquid products, can also be made of high purity oxygen and nitrogen, such as 99.998% oxygen and 99.998% nitrogen air separation equipment can also according to the needs of users, by computer control, at any time increase or decrease in the number of products, achieve the goal of economy with oxygen. By the 1980s, the oxygen production capacity of large air separation equipment had reached 70,000 meters (/ time; Air pressure drops to 0.36 mpa; The continuous operation period can reach more than 2 years.