Design of adjustment control for multi-layer belt dryer

The drying medium temperature of the multi-layer belt dryer is about 250 ° C, and a hot oil heating device installed in the dry casing body can be used. Compared with steam, hot oil has a high temperature, but low pressure, a small convective heat transfer coefficient, and a heat exchanger requiring a large heat transfer area.

In addition, the drying medium is directly heated by gas and fuel, and the operating temperature is higher. However, it should be noted that the contact of the heating medium with the product may cause contamination and therefore does not apply to materials such as dry foods and medicines. In order to save energy, the exhaust gas discharged from the dryer is above its dew point temperature, and can be exchanged with the fresh drying medium through the external heat exchanger, and the drying medium is preheated before entering the dryer.

The design of the adjustment control during operation of the multi-layer belt dryer:

The advantages and disadvantages of multi-layer belt dryer operation depend to a large extent on the distribution of the drying medium and the setting of the control system. There are usually several control points in engineering design:

1. The drying medium (air) passes through the louvered air inlet on the side of the box, and is mixed with a part of the exhaust gas and heated by the heating device, and then passes through the mesh belt to contact the material. The temperature of the drying medium before passing through the belt is controlled by the steam flow.

2. According to the resistance of the drying medium through the material layer, the running speed of the mesh belt will be controlled so that the resistance drop can be kept constant when the feeding amount changes (generally should be fixed as much as possible).

3. Adjust the exhaust gas output by the humidity of the exhaust gas or its wet bulb temperature.

4. When an accident occurs in the equipment or operation, the accident parking system ensures the sequential stop from the extrusion molding device-conveyor belt-circulation fan to the exhaust air exhaust fan.