In the rotary dryer, there are two kinds of forward flow and reverse flow depending on the direction of the flow of the material and the hot gas. The flow direction of the forward flow dryer is the same as that of the hot air flow. Why do most dryers use the downstream flow?
The main features of the forward flow type are as follows: (1) At the hot end of the dryer, the temperature difference between the material and the hot gas is large, the heat exchange process is rapid, and a large amount of moisture is easily evaporated. This method is suitable for materials with higher initial moisture content. 2 After the viscous material enters the dryer, the moisture on the surface is easy to evaporate, which reduces the adhesion and facilitates the movement of the material. When drying wet coal, it can avoid direct contact of hot gas with dry coal and cause fire. 3 The low pressure at the hot end of the downstream operation can reduce the amount of air leakage that enters the drying, which is helpful for stabilizing the temperature and flow rate of the hot gas in the dryer. 4 feeding and coal supply with the hot end of the dryer, the workshop layout is more convenient. 5 Downstream dryers have a low discharge temperature and can generally be conveyed by a belt conveyor.
In the full consideration of the characteristics of the material, particle size, the final moisture content of the material and the layout of the workshop and other specific circumstances, most manufacturers use the rotary dryer with a downstream type!