There are many types of equipment used for drying operations, which can be divided into atmospheric pressure and vacuum dryer according to the operating pressure. According to the operating method, it can be divided into intermittent and continuous types. According to the drying medium, it can be divided into air, flue gas, or other drying media. According to the modes of motion (material movement and drying medium flow), it can be divided into parallel flow, counter flow, and cross flow. 1、 According to the operating pressure

According to the operating pressure, dryers are divided into two types: atmospheric pressure dryers and vacuum dryers. Operating under vacuum can reduce the partial pressure of moisture vapor in the space, accelerate the drying process, and lower the boiling point of moisture and the drying temperature of materials. Steam is not easily leaked, so vacuum dryers are suitable for drying heat sensitive, easily oxidizable, explosive, and toxic materials, as well as situations where moisture vapor needs to be recovered.

2、 According to the heating method, dryers are divided into convection, conduction, radiation, dielectric and other types. Convection dryer, also known as direct dryer, uses a hot drying medium to directly contact wet materials, transfer heat through convection, and take away the generated steam; Conductive dryer, also known as indirect dryer, uses conduction to transfer heat from a heat source to wet materials through metal partition walls. The generated wet vapor can be removed by vacuum suction, introducing a small amount of purge gas, or condensing on the surface of a separately set low-temperature condenser. This type of dryer does not use a drying medium, has high thermal efficiency, and the product is not contaminated. However, its drying ability is limited by the heat transfer area of the metal wall, and its structure is also complex, often operated under vacuum; Radiation dryer uses various radiators to emit electromagnetic waves within a certain wavelength range, which are selectively absorbed by the surface of wet materials and converted into heat for drying; A dielectric dryer utilizes a high-frequency electric field to induce thermal effects inside wet materials for drying. According to the movement mode of wet materials

3、 According to the movement mode of wet materials, dryers can be divided into fixed bed type, stirred type, spray type and combined type; According to the structure, dryers can be divided into box dryers, conveyor dryers, drum dryers, vertical dryers, mechanical agitation dryers, rotary dryers, fluidized bed dryers, air flow dryers, vibration dryers, spray dryers and combination dryers.