5.4.6. Sorption by Adsorption


<BR>Drying compressed air by adsorption is a purely physical process. The moisture is bound to the drying agent by force of adhesion ( unbalanced molecular attraction ). The moisture stays on the inner and outer surfaces of the adsorption material without a chemical reaction taking place.

The adsorption material has an open porous structure and a large inner surface. The most common adsorption materials are aluminium oxide, silicagel, active carbon and molecular screens. Different adsorption materials are used for the various regeneration processes.
<BR><BR>
<BR>
<BR>
Operating principle

During the drying process the moist compressed air flows through an adsorption tank. The moisture is bound, which dries the compressed air. This process generates heat. The adsorption material must be regenerated when the adhesive forces are balanced by water deposits. This means that the water must be removed from the adsorption material. For this reason there must be two parallel drying tanks with continual operation. The active tank A dries the compressed air, while the inactive tank B regenerates without pressure.

The following processes are mainly used to regenerate the adsorption material :
    • cold regeneration
    • internal hot regeneration
    • external hot regeneration
    • vacuum regeneration