Classification of dryer

The dryer can be classified according to different characteristics such as operation process, operation pressure, heating method, wet material movement mode or structure. According to the operation process, the dryer is divided into two types: batch type (batch operation) and continuous type.

According to the operating pressure, the dryer is divided into two types: normal pressure dryer and vacuum dryer. Operating under vacuum can reduce the partial pressure of wet steam in the space to accelerate the drying process, and can reduce the boiling point of wet and the drying temperature of the material. Steam is not easy. Leakage, so the vacuum dryer is suitable for drying heat sensitive, oxidizable, explosive and toxic materials

According to the heating method, the dryer is divided into convection type, conductive type, radiation type, and dielectric type. Convection dryer, also known as direct dryer, is the use of hot drying medium in direct contact with wet materials to transfer heat by convection and take away the generated steam; conductive dryer is also called indirect dryer, it uses conduction The method transfers heat from the heat source to the wet material through the metal partition wall. The generated wet steam can be removed by vacuum suction, a small amount of purge gas, or condensation 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, the drying capacity is limited by the heat transfer area of the metal wall, and the structure is more complicated. It is often operated under vacuum. Radiation dryers use various types of radiation. The dryer emits electromagnetic waves in a certain wavelength range, which are selectively absorbed by the wet material surface and then converted into heat for drying; the dielectric dryer uses a high-frequency electric field to dry the wet effect inside the wet material.

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