Air dryers can be classified according to different characteristics such as operating process, operating pressure, heating method, wet material movement mode or structure.

According to the operation process, air dryers are divided into two types: batch type (batch operation) and continuous type;

According to the operating pressure, air dryers are divided into two types: atmospheric air dryers and vacuum air dryers. Operation under vacuum can reduce the partial pressure of moisture vapor in the space and accelerate the drying process, and can reduce the boiling point and Material drying temperature, steam is not easy to leak, so the vacuum air dryer is suitable for drying heat sensitive, easily oxidized, explosive and toxic materials and occasions where moisture vapor needs to be recovered;

According to the heating method, air dryers are divided into convection, conduction, radiation, and dielectric types. Convection air dryers, also known as direct air dryers, use hot drying media to directly contact wet materials, transfer heat by convection, and take away the generated steam; conductive air dryers are also known as indirect air dryers It uses conduction to transfer heat from the heat source to the wet material through the metal partition. The generated moisture vapor can be removed by vacuum suction, a small amount of purge gas or condensation on the surface of a separate low-temperature condenser. This type of air dryer does not use drying medium, has high thermal efficiency, and the product is not contaminated, but the drying capacity is limited by the heat transfer area of ​​the metal wall, and the structure is also more complex. It is often operated under vacuum; the radiant air dryer uses various This kind of radiator emits electromagnetic waves in a certain wavelength range, which are selectively absorbed by the surface of the wet material and then converted into heat for drying; the dielectric air dryer uses the action of a high-frequency electric field to make the wet material generate thermal effects for drying.

According to the movement mode of wet materials, air dryers can be divided into fixed bed type, agitation type, spray type and combined type; according to the structure, air dryers can be divided into chamber air dryers and conveyor air dryers , Drum air dryer, vertical air dryer, mechanical agitated air dryer, rotary air dryer, fluidized bed air dryer, air flow air dryer, vibration air dryer, spray air dryer Machine, and combined air dryer, etc.