A desiccant air dryer for compressed air uses spec...

A desiccant air dryer for compressed air uses special drying agent beads like silica gel and activated alumina to absorb water vapor from an air stream. These air dryer units are often regenerative so that the drying agent doesn’t need replacing in order to provide vapor-free compressed air consistently. In a desiccant dryer, adsorbing the water vapor onto the large, dry surface area of a highly porous material called desiccant dries the compressed air. This adsorption occurs as water vapor in the compressed air moves into the pores of the dry desiccant and is attracted to the surface of the pores. Wet air passes directly through the desiccant medium which adsorbs the moisture. The desiccant medium has a finite capacity for adsorbing moisture before it must be dried out, or regenerated. To do this, the tower containing saturated desiccant medium is depressurized and the accumulated water is driven off.