According to the heating method, the dryer is divided i […]
According to the heating method, the dryer is divided into a convection type, a conduction type, a radiation type, a dielectric type and the like. The convection dryer, also known as the direct dryer, uses a hot drying medium to directly contact the wet material to transfer heat in a convective manner and to carry away the generated steam. The conductive dryer is also called an indirect dryer, which utilizes conduction. The heat is transferred from the heat source to the wet material through the metal partition wall, and the generated wet steam can be removed by vacuum suction, a small amount of purge gas or condensation on the surface of the separately provided low temperature condenser.
This type of dryer does not use drying medium, has high thermal efficiency, and the product is not polluted, but the drying capacity is limited by the heat transfer area of the metal wall, the structure is also complicated, and it is often operated under vacuum; the radiant dryer uses various radiations. The electromagnetic wave emitted by a certain wavelength range is selectively absorbed by the surface of the wet material and then converted into heat for drying; the dielectric dryer uses a high-frequency electric field to cause a thermal effect inside the wet material to be dried.