Non Cryogenic processes of Air Separation Jul25

Non Cryogenic processes of Air Separation...

Non Cryogenic processes of Air Separation   Dry air contains by volume 78.08 % of nitrogen, 20.95 % of oxygen, and 0.93 % of argon along with traces of a number of other gases (Fig 1). Atmospheric air can contain varying amount of water vapor (depending upon humidity) and other gases produced by natural processes and human activities. Fig 1 Composition of air Non cryogenic air separation processes are near ambient temperature separation processes and are used for the production of nitrogen or oxygen as gases. These processes are cost effective choices when demand of gases are relatively small and when very high purity of the gases is not required. Non cryogenic plants are compact and produce gaseous nitrogen which is typically 95.5 % to 99.5 % oxygen free or gaseous oxygen which is 90 % to 95.5 % pure. Non cryogenic plants are less energy efficient than cryogenic plants (for comparable product purity) but at the same time cost less to build. The physical size of the plant can be reduced as required purity is reduced, and the power required to operate the unit is reduced as well.  Non cryogenic plants are relatively quick and easy to start up and can be brought on line in less than half an hour. This is useful when product is not needed full time. Like cryogenic plants, non cryogenic air separation processes also start with compression of air. Unlike cryogenic plants which use the difference between the boiling points of nitrogen and oxygen to separate and purify these products, non cryogenic air separation plants use physical property differences such as molecular structure, size and mass to produce nitrogen and oxygen. Non cryogenic processes are based on either selective adsorption or permutation through membranes. The most common technologies...