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.

The industry said that it is vital to perform the correct operation when running the spray dryer, and to understand the performance of all aspects of the equipment and possible problems, and to ensure the longevity of the equipment and the stability of the operation of the enterprise.

Among them, the sticking phenomenon is a prominent problem that hinders the normal operation of the spray dryer, and the spray drying process of the solid preparation (especially the traditional Chinese medicine) is particularly obvious. The sticky wall of the material is not only unfavorable for the collection operation, but as time goes on, the sensitive sticky wall material will deteriorate into a non-conforming material.

In order to break the stickiness phenomenon, many operators try to solve the problem from the technical point of view, including the selection of suitable solvents, adding excipients, changing process parameters, etc., but the room for adjustment of these methods is not very large, so it must be sought from the perspective of equipment. The fundamental solution.

Among them, domestic and foreign experts have studied the problem of sticking wall and agglomeration in the drying process, and believed that the main cause of sticking wall is wall temperature. There are three cases 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 are already in contact with the wall before they reach the surface drying, and thus stick to the wall. The position of the sticky wall is generally on the plane facing the movement track of the droplet sprayed by the atomizer, and the mist. The structure of the converter, the hot air is related to the state of motion within 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, adhering to the wall;

The surface of the dry powder adheres. Dry powder in the 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 hammering 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.

In addition to mastering the above five phenomena to prevent sticking, the spray dryer cleaning and related maintenance methods need to be mastered.

At present, the development of domestic medicine is in good shape, and the market is increasingly demanding medical equipment. Spray dryers will face more challenges in the new environment. Of course, in addition to meeting the requirements of materials, GMP, energy saving, spray dryer manufacturers must carry out innovative research and development around the production process, but also to improve and upgrade according to customer conditions.