Air compressor dryers

What is Dryers in compressor used for?

A dryer is used in a compressor to lower the dew point by removing moisture content in it. Other than aftercoolers to produce quality, less humid air, dehydration must be provided using the dryer.

Generally, there are a different type of dryers:

  • Absorption type dryer

  • Adsorption type dryer

  • Refrigeration dryer

Absorption type dryer:

The absorption dryer is a pressure vessel, drying agent like phosphoric pentaoxide are placed at the top of the vessel and the moisture is condensed at the bottom of the vessel.

The compressed is air passed through the dryer, air reacts with the drying agent to break down and thus the moisture discharge into the fluid and condensate at the bottom of the vessel. Oil vapour and oil particles are also separated in the absorption dryer.


  • Simple to install

  • Low mechanical wear because there are no moving parts

  • No external energy requirement


  • Maintenance cost is high
  • Low efficiency
  • Consumable cost is high

Adsorption type dryer:

Adsorption is a physical process of moisture removal on the porous surface of certain granular materials. Gaseous molecules are attracted to certain solid surfaces by van der walls forces and this causes the adsorption.

This type of dryer consists of two chamber, Both the chamber is filled with desiccants. The wet compressed air is passed through both the chambers. Water vapour in the compressed air is absorbed by the desiccant. Thereafter dry air is allowed to pass to the application through the after filter.

The twin tower design facilitates simultaneously compressed air drying and saturated desiccant regeneration for non-stop production.

Refrigerated dryer

The refrigerated dryer consists of two stages, stage 1 is a heat exchanger and stage 2 is refrigeration to reduce the temperature of the compressed air. The incoming warm and humid air is first passed through the air-to-air heat exchanger, and then through the refrigerating unit to reduce the temperature of the compressed to as low as +2°C.

This drying method is based on the principle that if the compressed air is cooled to a temperature below the dew point, condensation talks place and water is precipitated. The whole water and oil content can be condensed on the chamber.