Air separation; is the process of separating atmospheric air into its main constituents such as oxygen, nitrogen, and other noble gases such as argon, xenon, etc.

Major methods of air separation:
· Cryogenic
· PSA: Pressure Swing Adsorption
· Membrane

Cryogenic Theory:
It is a branch of physics that includes the production conditions and effects of super-cold temperatures. In this case, all equipment must be able to work with these temperatures.
One of the most widely used fields of this branch of science in the field of industry is the production of major industrial gases such as oxygen, nitrogen, argon, etc. by separating them from the air using the boiling point of these gases, which is done on a large scale today.
Air is a mixture of different gases such as N2, O2, He, CO2, Ar, Ze, each of which has a different condensing temperature. This difference of degrees makes it possible to control each of these gases with very high purity and separate them as a liquid by controlling the temperature of the distillation system.
The resulting liquid is very cold and for transportation and use by transmission lines and equipment, functions such as conversion and phase change, devices and control systems require special facilities that are among the most advanced technologies in terms of standards, structural, functional complexity and safety.

Cryogenic Process:
This method was first invented by a German scientist named Dr. Carl von Linde. Although it is costly in terms of initial investment and the energy consumption, due to the high capacity and purity of the product obtained, it is widely used today in many projects that require the production of industrial gases. The purity available in this system is up to 99.999%.
In this process, the air is compressed and after the necessary processing, it is cooled to liquefaction, then these liquids enter the distillation column with different boiling temperatures. This process requires a relatively “significant” range of specific equipment and services.