吸附式干燥机（吸干机）工作原理是利用吸附剂吸附水分的特性来降低压缩空气中水分的含量，一般吸干机出口气的压力露点可达到-20℃~-70℃。

常见的吸干机吸附剂有活性氧化铝、分子筛等，而吸干机要获得极干燥压缩空气时，分子筛是的选择。

活性氧化铝，它是一种多孔性、高分散度的固体材料，有很大的表面积，其微孔表面具备催化作用所要求的特性，如吸附性能、表面活性、优良的热稳定性等，所以被广泛地用作化学反应的催化剂和催化剂载体。

分子筛是指具有均匀的微孔，其孔径与一般分子大小相当的一类物质，分子筛的应用非常广泛，可以作高效干燥剂、选择性吸附剂、催化剂、离子交换剂等。

与其他吸附材料相比，分子筛的比较大特点是具有均一直径的微孔结构，因而能有选择性地吸附直径小于其孔径的气态分子。

分子筛一般都是人工合成的，在空气干燥分离工艺中得到较多的分子筛是沸石型硅铝酸盐的多水化合物晶体。

其热稳定性和化学稳定性很高，而且还同时具有筛分性能、离子交换性能、选着单一性和吸附性能良好等特点，通常被应用于吸附式干燥机吸附腔体中。

The working principle of the adsorption dryer (suction dryer) is to reduce the moisture content in the compressed air by using the moisture adsorption characteristics of the adsorbent. Generally, the pressure dew point of the outlet air of the suction dryer can reach - 20 ℃ ~ - 70 ℃.

The common adsorbents of the dryer include activated alumina and molecular sieve. When the dryer wants to obtain extremely dry compressed air, molecular sieve is the only choice.

Activated alumina, which is a porous and highly dispersive solid material, has a large surface area. Its microporous surface has the characteristics required by catalysis, such as adsorption performance, surface activity, excellent thermal stability and so on. Therefore, it is widely used as catalyst and catalyst carrier for chemical reaction.

Molecular sieve is a kind of material with uniform micropores and its pore size is equivalent to the general molecular size. Molecular sieve is widely used as high-efficiency desiccant, selective adsorbent, catalyst, ion exchanger and so on.

Compared with other adsorption materials, the biggest feature of molecular sieve is its microporous structure with uniform diameter, so it can selectively adsorb gaseous molecules with diameter less than its pore size.

Molecular sieves are generally synthetic. Most of the molecular sieves obtained in the air drying separation process are zeolite aluminosilicate polyhydrate crystals.

It has high thermal and chemical stability, and also has the characteristics of screening performance, ion exchange performance, singleness of selection and good adsorption performance. It is usually used in the adsorption chamber of adsorption dryer.