The principle and function of the dryer

A dryer is a mechanical device that uses heat energy to reduce moisture in a material and is used to dry objects. The dryer evaporates the moisture (generally refers to moisture or other volatile liquid components) in the material by heating to obtain a solid material with a predetermined moisture content. The purpose of drying is for material use or further processing needs. For example, the drying of wood before the production of wooden molds and woodware can prevent the deformation of the product. The drying of the ceramic material before calcination can prevent the finished product from cracking. In addition, the dried material is also easy to transport and store, such as drying the harvested grain below a certain moisture content to prevent mildew. Since natural drying is far from meeting the needs of production development, various mechanized dryers are increasingly used.

The drying process requires the consumption of large amounts of heat energy. In order to save energy, certain high moisture content materials, suspensions or solutions containing solid materials are generally first mechanically dehydrated or heated to vaporize, and then dried in a dryer to obtain dry solids.

During the drying process, the heat and mass (moisture content) transfer must be completed at the same time to ensure that the moisture partial pressure (concentration) on the surface of the material is higher than the moisture partial pressure in the external space and the heat source temperature is higher than the material temperature.

The heat is transferred from the high temperature heat source to the wet material in various ways, vaporizes the surface of the material and disperses into the external space, so that the difference in moisture content occurs on the surface and inside of the material. The internal moisture spreads to the surface and vaporizes, so that the moisture content of the material is continuously reduced, and the overall drying of the material is gradually completed.