Regenerative compressed air dryers use desiccant to adsorb water vapor from the compressed airstream. In the twin tower design one tower dries the air from the compressor while the desiccant in the other tower is being regenerated to provide continuous operation. These dryers are typically referred to as “heatless” or “heated”. Heatless dryers do not use any source of heat for regeneration other than the heat given o during the drying phase. This is known as the “Heat of Adsorption”. Heated dryers, on the other hand, utilize an external heat source for regeneration and require little or no process air.
The Aircel AZP Series Dryers (600 – 10,000 scfm) utilize externally heated atmospheric air for regeneration of the desiccant bed. This significantly reduces the use of compressed purge air for regeneration resulting in an overall reduction in the cost of operation. Process air is only consumed during depressurization of the offline tower and during cool-down of the regenerating bed. This amounts to an average process air use of 2% of the rated capacity of the dryer.