1、 The mesh belt dryer is composed of several independent unit sections, each of which includes a circulating fan, a heating device, a separate or public fresh air suction system and a tail gas discharge system. Therefore, the number of drying media, temperature, humidity and exhaust gas circulation can be controlled independently, so as to ensure the reliability of the work and optimize the operating conditions. The operation of the belt dryer is flexible, the wet material feeding and drying process are carried out in the sealed box, the degree of automation is high, the working conditions are good, and the leakage of dust is avoided. The dried material of belt dryer moves with the conveyor belt, the relative position of material particles is relatively fixed, and the drying time is basically the same. Belt dryer is very suitable for drying materials with uniform color change or even moisture content.
2、 The structure of belt dryer can be divided into three types according to different combination forms, namely single-stage, multi-stage and multi-layer belt dryer.
（1） The material to be dried in the single-stage belt dryer is evenly distributed to the conveyor belt by the feeding end through the feeding device. The conveyor belt is usually made of perforated stainless steel sheet and driven by the motor through the gearbox. The commonly used drying medium is hot air. The air is pumped from the outside through the air filter by the circulator, heated by the heater, and vertically blown up from the lower part of the conveyor belt through the distribution board. When the hot air flows through the material layer, the moisture in the material will vaporize, the air will be humidified, and the temperature will decrease. Part of the wet air will be discharged from the box, and the other part will be mixed with fresh air at the inlet of the circulating fan for recycling. The dried product is directly contacted and cooled by external air or other low-temperature medium, and then discharged from the end.
（2） Multistage belt dryer multistage belt dryer is essentially composed of several (up to 4) single-stage belt dryers in series, and its operation principle is the same as that of single-stage belt dryer. In the early stage of drying, the materials with high shrinkage, such as some vegetables, will accumulate thick on the conveyor belt, which will cause compaction and affect the flow of drying medium. At this time, the multi-stage belt dryer can be used to improve the total production capacity of the unit.
（3） The multi-layer belt dryer is composed of several single-stage belt dryers connected in series in a sealed drying chamber from top to bottom. The number of layers is up to 15, usually 3-5. The conveying speed of one or more layers is low, which makes the material layer thicker. In this way, most of the drying medium flows through the first few thinner material layers, so as to improve the overall drying efficiency. A partition board is arranged between the layers to promote the directional flow of the drying medium and make the material dry evenly. The multi-layer belt dryer is composed of heat insulation case, conveyor chain mesh belt, chain tension device, moisture removal system, transmission device, anti stick steering conveyor belt, indirect heating device, etc. The lower exit conveyor belt generally extends 2-3m out of the box, leaving space for workers to pick out deformed and imperfect products during drying.