Structurally, a membrane represents a cylindrical cartridge functioning as a spool with specifically reeled polymer fibers. Gas flow is supplied under pressure into a bundle of membrane fibers. Due to the difference in partial pressures on the external and internal membrane surface gas flow separation is accomplished.
Nitrogen PSA generator consist of two towers containing CMS ( Carbon Molecular Sieves). Air is compressed dried and purified before entering the towers. While one tower is producing nitrogen the other one is regenerating CMS by depressurization.
The main purpose of a cryogenic nitrogen plant is to provide a customer with high purity gaseous nitrogen (GAN). In addition liquid nitrogen (LIN) is produced simultaneously and is typically 10% of the gas production. High purity liquid nitrogen produced by cryogenic plants is stored in a local tank and used as a strategic reserve. This liquid can be vaporised to cover peaks in demand or for use when the nitrogen plant is offline.