A desiccant air dryer system consists of two towers, one for drying the air and the other for regenerating the desiccant. The drying tower contains a porous desiccant material that inhibits water molecules as compressed air from the inlet passes over it.

A less common variant, the single-tower desiccant air dryer, comprises a single tower containing a desiccant material that dries air coming in from the environment. Single-tower dryers also contain no mechanical parts and do not require electricity to operate. They are suitable for use in hazardous and corrosive environments.

These instrument air dryers use a desiccant material, hygroscopic substances that exhibit a high affinity for water as the de-humidification agent. These types of compressed air dryers achieve a low dew point, making them suitable for use in colder climates and industries that require super dry air.

There are three main types of desiccant dryer systems – heated, heatless, and heat compression desiccant air dryers. Let’s take a closer look at these below.

Heated desiccant air dryer

Heated desiccant air dryers utilize a source of heating within the drying tower to heat the desiccant material sufficiently to minimize the need for purging air. Typical dew points in heated dryers range from -40°C to -73.3 °C (–40 to –100 °F).

Heatless regenerative desiccant air dryer

Heatless desiccant dryers do not contain a heated system in the regenerating tower; instead, they utilize “purge air” to expel moisture from the tower. Typical dew points in heatless dryers range from -40°C to -73.3 °C (–40 to –100 °F).

Heat of Compression

A heat of compression air dryer uses both towers simultaneously to maintain a uniform temperature. This design allows for lower operating costs but with a less consistent dew point.