The general working principle of desiccant air dry...

The general working principle of desiccant air dryers is simple: moist air flows over hygroscopic material (typical materials used are silica gel, molecular sieves, activated alumina) and is thereby dried. The exchange of water vapor from the moist compressed air into the hygroscopic material or "desiccant", causes the desiccant to gradually be saturated with adsorbed water. Therefore, the desiccant needs to be regenerated regularly to regain its drying capacity, and adsorption air dryers are typically built with two drying vessels for that purpose: The first vessel will dry the incoming compressed air while the second one is being regenerated (Similar to the workings of a nitrogen generator). Each vessel ("tower") switches tasks when the other tower is completely regenerated. Typical PDP that can be achieved is -40°C, which makes these dryers suitable for providing very dry air for more critical applications. There are 4 different ways to regenerate the desiccant, and the method used determines the type of adsorption dryer.