In the past two decades PSA (Pressure Swing Adsorption) Technology has gained widespread commercial acceptance as the technology of choice for gas separation because of its ability to produce gas on site, especially in Africa.
The essential requirement is an adsorbent that preferentially adsorbs one component (eg: O2, N2) from a mixed feed (Air). Clean, dry compressed air is fed, in carefully timed increments, through two chambers filled with Zeolite Molecular Sieve (adsorbent). Through a calculated process of ”feeding”, “purging” and “equalization” and depending on the type of sieve used, the resultant gas is produced.
The quality of the resultant gas is directly linked to the supply air feed. As with any process that involves inputs and outputs, a “poor” input negatively affects the output and hence the need for the highest quality air. The scale and size of the PSA system is directly proportional to the quantity of product gas required and ranges from a few litres per day (Portable Medical O2 Concentrators) right up to hundreds of kilograms/tonnes per day. PSA technology has rapidly gained in popularity and acceptance in the medical industry to produce oxygen, particularly in remote locations where bulk cryogenic or compressed cylinder storage/supply is not possible.
To the right is a schematic drawing of a typical PSA system used for the production of on-site Nitrogen/Oxygen.