The desiccant bed contains pellets or granules that absorb moisture. These pellets are commonly known as molecular sieves. These molecular sieves have a strong molecular attraction to water which allows it to efficiently remove moisture from the passing air.

The desiccant dryer uses a blower to draw cooled air from the hopper and forces the air through a moisture absorbing ‘desiccant bed’. After moisture is removed in the desiccant bed the air is heated before reaching the pellets in the hopper. Unfortunately, as they absorb moisture from the air, the desiccant bed starts to become saturated. Once the desiccant reaches its maximum saturation level, it can no longer absorb any moisture.

The operation of expelling moisture from the desiccant and drying it is called regeneration. During regeneration a separate heating system passes heated air through the desiccant bed causing the desiccant to give up the moisture. Because of this regeneration process, most desiccant dryers have at least two desiccant beds so that there is always dried desiccant available for material drying.

-Andy