How PSA Works
PSA technology works on the concept of adsorption to produce a continuous stream of nitrogen gas from compressed air. Nitrogen generator consists of two adsorption towers filled with adsorbent material called Carbon Molecular Sieve (CMS). The PSA process cycle consists of two key mechanisms: “Pressurisation / Adsorption” and “Depressurisation / Desorption”.
Compressed air, which consists of approximately 21% oxygen and 78% nitrogen, is passed through a tower of carbon molecular sieve (CMS). The sieve preferentially adsorbs Oxygen and Moisture over Nitrogen allowing Nitrogen to pass through as a product gas at pressure. While one of the tower is in the adsorption phase the other tower is regenerated by de-pressurizing which means the sieve releases the adsorbed gases to the atmosphere and the cycle is then repeated.
A solid-state programmable controller operates the process valves on an alternating cycle with built-in logic for automatic stop/start. Nitrogen flow and purity remain constant regardless of the peak usage demands. Under normal operating conditions and with correct maintenance the carbon molecular sieve will have an almost indefinite life times.
Carbon molecular sieve differs from ordinary activated carbons in that it has a much narrower range of pore openings. This allows small molecules such as oxygen to penetrate the pores and be separated from nitrogen molecules, which are too large to enter the CMS. The larger molecules of nitrogen by-pass the CMS and emerge as the product gas.