For PSA pressure swing adsorption molecular sieve air separation equipment, molecular sieve is the core component of the system; only clean compressed air through the molecular sieve continuous adsorption and regeneration, in order to continue the production of nitrogen or oxygen we need.
Regeneration can be understood as the reverse process of adsorption; because when the molecular sieve completes a saturated adsorption, it cannot continue to adsorb gas, and its adsorption capacity needs to be "restored", which is what we call "regeneration".
Molecular sieve "regeneration" can help molecular sieve life as long as possible and maintain good performance. After the correct regeneration of the molecular sieve, the adsorption and mechanical properties of the decay and aging is very low. There are two methods for regenerating molecular sieves;
1) Change the temperature. It is to heat the molecular sieve to remove the metal ions and combined water with lower electric valence and larger ionic radius in the molecular sieve, so that it can return to the cavity state; in industrial production, it will be heated with preheated regeneration gas to purge the molecular sieve and take away the desorbed adsorbate. Generally speaking, the regeneration temperature of molecular sieve is recommended to be 200~250 degrees. If the temperature is too high, the micropores of the molecular sieve will be permanently blocked and the molecular sieve will fail.
2) Change the relative pressure. Generally used in gas phase adsorption process. The basic method is to keep the adsorbent temperature constant, by reducing the pressure and inert gas back blowing, remove the adsorbate.
Regeneration is usually carried out in reverse with adsorption, and most of the adsorbates contained at the inlet of the adsorption bed do not need to pass through the entire bed, which effectively reduces the contact between the molecular sieve and the hot and humid gas and improves the service life of the molecular sieve. Of course, the regeneration gas should be as dry as possible, otherwise it will affect the adsorption efficiency.
As for whether the regeneration is qualified or not, the usual judgment method is to look at the instrument. The regeneration time and temperature curve of the same tower recorded by the instrument remain normal and the fluctuation value is stable. Moreover, when the same tower is put into adsorption again, the gas concentration (purity) of the sampled product is within the qualified range, and the variation range is very small, which indicates that the regeneration is complete.