Kaeser externally heat-regenerative blower purge desiccant dryers produce dew points as low as -40°F. Twin desiccant beds of activated alumina alternate between drying and regenerating, with regeneration being accomplished with heated ambient air at just above atmospheric pressure. The heated ambient air readily drives adsorbed moisture off of the desiccant preparing the it for another adsorption cycle. The moisture-laden regeneration air exhausts to atmosphere during the regeneration process. KBD dryers can regenerate with little (about 1%) or no process (purge) air loss.
Solid state logic accurately controls inlet and purge valves which direct wet compressed air to the regenerated tower, and heated ambient air to the tower in need of regeneration. The process of adsorption and desorption can be repeated several thousand times before the desiccant must be replaced.