Activated alumina dryer is a common equipment for compressed air to remove water and dry. When preparing dry compressed air with a pressure dew point below zero in the industry, the activated alumina adsorption dryer is almost the only choice. Before in-depth research or proper use of activated alumina adsorption dryer, it is necessary to understand the adsorption principle and adsorbent.

Adsorption, also known as sorption, is a natural phenomenon in which the concentration of substance molecules at the interface of two phases automatically changes. Studies have shown that the adsorption phenomenon not only occurs on the solid-gas interface, but also on the liquid-gas interface and solid-liquid interface.

The adsorption system is composed of adsorbent and adsorbate. We call materials with a certain adsorption capacity as adsorbents and the adsorbed materials as adsorbates. In the compressed air dryer, the commonly used adsorbents are silica gel, activated alumina and molecular sieves. The water vapor uniformly mixed in the compressed air is the adsorbate.