The simplified diagram above outlines the major components in a Pressure Swing Adsorption Process (PSA). The key to selective gas separation is the choice of sieve material packedMembrane systems from CEGS incorporate the most efficient modules available to minimize feed air compression requirements, ultimately saving our clients rental and fuel costs. Booster compressors have been provided to deliver up to 3000 psig, avoided the need for cryogenic pumpers for a wide range of customers. in the dual containers or vessels.

For nitrogen service, a carbon molecular sieve (CMS) is typically used. The physical pore size of the sieve enables smaller O₂ molecules to be adsorbed on the surface of the sieve. The rate of loading is also faster for the oxygen (kinetic separation effect), so the surface of the sieve adsorbs most of the O₂, and the nitrogen molecules are allowed to pass by the sieve as the product gas. The higher the pressure, the greater adsorption capacity of the CMS.

Before the CMS reaches equilibrium, when N₂ will also be adsorbed, the pressurized gas in the first vessel is vented to the second vessel that is at lower pressure. Residual O₂ in the first vessel is then “desorbed” from the CMS and vented at atmospheric pressure. All required valving operations are done automatically by carefully calculated timing cycles controlled by a PLC.

The “product” N₂ gas from both adsorption towers is collected in a common receiver vessel. N₂ purities of 99.99% are possible by the PSA process.

For oxygen service, the CMS is replaced with specialized zeolites to preferentially adsorb nitrogen, thereby delivering O₂ at approximately 95% purity with the same process diagram shown above.