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How to prevent the spray dryer from sticking to the wall?

Technical Knowledge 2019-03-26 09:08:48
The spray dryer sprays the material into droplets and disperses it in hot air. The materials are in contact with the hot air in a cocurrent, countercurrent or mixed flow manner, so that the water evaporates quickly to achieve the purpose of drying. By means of spray drying, unit operations such as concentration, filtration, and pulverization can be omitted, and drying time is short, product fluidity and fast solubility are good, and thus it is widely used in medicine and other industries.

There are three kinds of situations in which the spray dryer appears to stick to the wall:

The semi-wet material sticks to the wall. The reason is that the sprayed droplets have already contacted the wall before they have dried on the surface, and thus adhered to the wall. The position of the sticky wall is generally on the plane facing the movement path of the droplets sprayed by the atomizer, and the mist. The structure of the converter, the hot air is related to the state of motion in the tower;

 Hot melt adhesive wall of low melting point material. The reason is that the material reaches a melting point at a certain temperature and begins to melt and become sticky and adheres to the wall;

The surface of the dry powder adheres. Dry powder moving in a limited space will always touch some of the wall, which is unavoidable, but such a sticky wall is generally not thick, as long as it can be shaken by air blowing or tapping gently, simply solve The solution is to polish the inner wall, which can solve this problem to some extent.

After finding out the cause of the stickiness phenomenon, the industry has listed five ways to prevent sticking:

1. Use a wall-mounted drying tower with air cooling to keep the wall temperature below 50 °C.

2. Introducing a secondary air cooling tower wall through the tangential direction of the tower wall cyclone;

3. Install an air broom consisting of a row of nozzles near the wall of the tower and slowly rotate it along the tower wall;

4, the tower wall increases the air hammer, through the impact of the air hammer, forcibly make the sticky wall material detach;

5. Increase the processing precision of the equipment, and the inner wall polishing of the tower can also reduce the sticking wall.

Tags china spray dryer vacuum spray freeze drying small lab spray dryer centrifugal spray dryer low temperature spray dryer