A desiccant dryer, also called an adsorption dryer, removes moisture from compressed air using a porous drying material such as silica gel or activated alumina.
Compressed air flows through a bed of desiccant. The material adsorbs water vapor, trapping moisture on its surface while the dry air passes through. This process allows the dryer to achieve very low dew points, typically down to −40 °C or lower.Once the desiccant becomes saturated, it must be regenerated. This is usually done in two ways:
• Heatless (pressure swing) regeneration: a small amount of dry air is used to purge and remove the stored moisture.
• Heat regeneration: the desiccant is heated to release the moisture.
Most desiccant dryers use two drying chambers, allowing one to dry the air while the other regenerates the desiccant. This ensures a continuous supply of dry compressed air.
Desiccant dryers are commonly used in applications where very dry air and high air purity are essential, such as manufacturing, laboratories, and moisture-sensitive processes.