These desiccant air dryer air diffuser are used in applications that require compressed air at dew points as low as -100°F. Through two identical drying towers, each containing a desiccant bed, air flows alternately. While one tower is on-stream drying, the other is off-stream being regenerated. Purge air is used to regenerate the desiccant. 

Diameter and length of desiccant beds determine drying efficiency. Bed diameter controls air velocity through the bed. If velocity is too high, the desiccant will float or fluidize, causing desiccant degradation. Bed length determines consistency of the dew point: the bed must be long enough to ensure sufficient contact time between the wet air and the dry desiccant to each the proper outlet dew point. 

Channeling, when an air stream finds a path through the bed and follows the path instead of flowing evenly throughout the bed, is often a problem with desiccant air dryer air diffuser. Channeling can be avoided by using stainless steel diffusers in the inlet and outlet of the desiccant towers and controlling air velocity through the desiccant bed. 

Desiccant air dryer air diffuser are either cold regenerative or heat regenerative. In cold regenerative dryers, 15% of dried compressed air is diverted from the air outlet and is used to purge the wet desiccant bed. In heat regenerative desiccant air dryer air diffuser, purge air is heated to 300 to 400°F and directed through one of the desiccant towers. Depending on the heated dryer type (internally heated, externally heated, blower purge, etc.), only a small percentage of 1 to 7% of purge air is diverted from the dried air stream. Valuable purge air is saved, reducing operating costs up to 40% in applications over 500 cfm.