Adsorption dryers PSA type (Pressure Swing Adsorption) consist of two pressure vessels, which are both filled with desiccant and are alternately switched-over during process of drying and regeneration..
The compressed air that needs to be dried flows through a vessel where the moisture is thoroughly removed by the desiccant (adsorption). At the same time, the moisture stored in the desiccant in the second vessel is removed (regeneration). If the desiccant in the vessel in which adsorption takes place is saturated with moisture, the vessels are switched and the process starts again.
One complete run of adsorption and regeneration in a vessel is called a cycle, and the time required is the cycle time.