BELT TYPE DRIER

The principle of work is shown in Fig. The raw material to be treated should be distributed on the conveyer screen belt. The screen belt is made from 12-60 mesh of stainless steel wire. It will be moved inside the drier through driving apparatus. The dry section consists of several units, each unit uses hot air circle separately. In which, parts of tail air are discharged through fan 6. The discharged air amount is controlled through regulation valve 7. At upper circle unit, air from circle fan 5 enters into the low chamber of unit through side duct. Air stream to be heated is up forward through heat exchanger 4 and then is distributed through distributor 3 and finally is injected to the screen belt and is penetrated to raw material and entered into upper chamber. The dry process is a conduction process of heat and mass when hot air passes through the layer of raw material. The air duct of upper chamber is connected with inlet of fan. Most of air stream is circulated. Small parts of air that is low n temperature and contains more moisture will be discharged through moisture removing duct, regulation valve and fan as wasted air. At low circle unit, air form circle fan enters into the upper chamber first, then heated through heat exchanger and penetrates the layer of raw material and enters into low chamber. The low chamber is connected to the inlet of fan through side air duct and air returning duct. Most of air stream is circulated. Small parts of air will be discharged. The upper and low units can be equipped flexible in accordance with the requirements of customers. The amount of unit can also be chosen in accordance with practical needs. For Dehydrated vegetable, in general 3 sets will be in series for use. That is to say it consists of primary dry section, middle dry section and final dry section. At primary dry section, because raw material contains more moisture and is poor in air permeability, the thickness of raw material to be dried should be thin and the fast operation speed is adapted and the higher dry temperature is applied. For raw material in which the temperature is not permitted to over 60, at the primary dry section, the temperature should be below 120 and the stay time at final dry section should be 3-6 times than primary dry section and the thickness of raw material should be 2-4 times than primary dry section. For raw material in which the temperature is not permitted to over 60, about 80 of dry air can be used. Hot air tempreture of every section can be independently controlled, and also multi-sections can be combined, the raw material can be dried uniformly and suitable for different kinds of materials.