AirScience - Model VPSA - Vacuum Pressure Swing Adsorption Process System
This process is primarily used for the dehumidification of biogas destined to the production of compressed natural gas (CNG) whether for transportation CNG or pipeline CNG. The process is very similar to the VSA process with the exception that the feed gas is under pressure and that the desorption sequence is designed to minimize the loss of methane as well as the energy usage (loss of pressure).
Generally the process consists of four (4) towers in parallel which can be expanded up to eight towers. At all times one tower is in the adsorption mode while others are each in one of depressurization, vacuum, re-pressurization modes.