How to prevent the spray drying machine from sticking to the wall?

　　There are many classification methods for spray dryer, which can be divided into parallel flow, counterflow and mixed flow according to gas liquid flow direction. According to the installation mode of atomizer, it can be divided into upper spray and lower spray and upper spray; According to the structure of atomizer, it can be divided into centrifugal type, pressure type and air flow type; According to whether the heating gas is circulating or not, it can be divided into open type, partial circulating type and closed type.

　　Sticking phenomenon is a serious problem that hinders the normal operation of spray dryer. The spray drying process of solid preparations (especially Chinese Medicine) is particularly obvious. Material adherence is not only bad for collection operation, but also as time goes on, sensitive wall spray dryer will deteriorate into unqualified material. From the point of view of technology, the solutions include the selection of appropriate solvents, the addition of excipients, and the change of process parameters. However, there is not much room for these methods to be adjusted, so we must seek a fundamental solution from the perspective of equipment. Experts at home and abroad have studied the problems of wall sticking and caking in the drying process, and they think that the main reason for wall sticking is the wall temperature.

　　Spray drying machine adhered to the wall generally in three ways:

　　1. Semi wet materials stick to the wall: the reason is that the spray droplets have contacted with the wall before reaching the surface drying, so they stick to the wall. The position of sticking to the wall is generally on the plane of the movement track of the spray droplets from the atomizer, which is related to the structure of the atomizer and the movement state of the hot air in the tower;

　　2. The reason is that the material reaches the melting point at a certain temperature and begins to melt and stick to the wall;

　　3. Surface adhesion of dry powder: when dry powder moves in limited space, some of them will touch the wall, which is unavoidable. However, such adhesion is generally not thick. As long as it is blown by air or gently knocked, it can shake off. The simplest solution is to polish the inner wall, which can solve this problem to a certain extent.

Here are five ways to prevent wall sticking:

　　1. The wall temperature is kept below 50 ℃ by using the sandwich drying tower, which is cooled by air;

　　2. The secondary air is introduced into the wall of the cooling tower tangentially through the wall swirl plate;

　　3. An air broom composed of a row of nozzles is installed near the wall of the tower, and the broom rotates slowly along the wall of the tower;

　　4. The air hammer is added to the tower wall, and the material adhering to the tower wall is forced to separate by the percussion of the air hammer;

　　5. Increasing the machining accuracy of the equipment and polishing the inner wall of the tower can also reduce the sticking.

　　Sticking phenomenon is a serious problem that hinders the normal operation of spray dryer. The spray drying process of solid preparations (especially Chinese Medicine) is particularly obvious. Material adherence is not only bad for collection operation, but also, with the extension of time, sensitive wall materials will change the quality of spray dryer into unqualified materials. From the point of view of technology, the solutions include the selection of appropriate solvents, the addition of excipients, and the change of process parameters. However, there is not much room for these methods to be adjusted, so we must seek a fundamental solution from the perspective of equipment. Experts at home and abroad have studied the problems of wall sticking and caking in the drying process, and they think that the main reason for wall sticking is the wall temperature.