Spray drying is a process that is widely used in the liquid process forming and drying industries. Zui is suitable for the production of powdered, granulated or bulk solid products from solutions, emulsions, suspoemulsions and pumpable paste liquid materials. Therefore, spray drying is an ideal process when the particle size distribution, residual moisture content, bulk density and particle loading of the finished product must meet precise standards. By adopting the drying method, the gas-solid two-phase contact surface area in the spray dryer is large, and the drying time is short, generally 5 to 30 s, which is suitable for drying the heat sensitive material.
The product obtained by drying has good performance, and particles of 30 to 50 mm can be obtained, and the product has good fluidity and fast solubility. The disadvantage is that the dryer has a large volume and a low heat transfer coefficient, resulting in low thermal efficiency and high power consumption.
There are many classification methods for spray dryers. According to the flow direction of gas and liquid, it can be divided into parallel flow, counter flow and mixed flow; according to the installation method of atomizer, it can be divided into upper spray type and lower spray type; The structure can be divided into centrifugal type, pressure type and air flow type; according to whether the heating gas is circulated, it can be divided into open type, partial circulation type and closed type. 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.
From a process point of view, the solution includes selecting the right solvent, adding the excipients, and changing the process parameters. However, there is not much room for adjustment of these methods, so a fundamental solution must be sought from the perspective of the equipment. Experts at home and abroad have studied the problem of sticking and agglomeration during the drying process. It is believed that the main cause of sticking is the wall temperature.
There are three kinds of cases in the spray dryer: 1. The semi-wet material sticks to the wall: the reason is that the sprayed droplets have already contacted the wall before the surface is dried, thus sticking to the wall and sticking to the wall. Generally speaking, it is on the plane of the trajectory of the droplet sprayed by the atomizer, and the structure of the atomizer, the movement state of the hot air in the tower; 2. The hot-melt adhesion of the low-melting material: the reason is that the material is At a certain temperature, the melting point begins to melt and becomes sticky, and adheres to the wall; 3. The surface adhesion of the dry powder: the dry powder moves in a limited space and there will always be some impact on the wall, which is unavoidable. However, such a sticky wall is generally not thick, as long as it can be shaken by air blowing or tapping gently. Zui's simple solution is to polish the inner wall, which can solve this problem to some extent.
Here are 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. Changzhou Binda Dry Granulation Equipment Co., Ltd. specializes in the production of spray dryers. The company's quality policy: market-oriented, customer satisfaction as the purpose, continuous improvement, and advanced behavior.
The product obtained by drying has good performance, and particles of 30 to 50 mm can be obtained, and the product has good fluidity and fast solubility. The disadvantage is that the dryer has a large volume and a low heat transfer coefficient, resulting in low thermal efficiency and high power consumption.
There are many classification methods for spray dryers. According to the flow direction of gas and liquid, it can be divided into parallel flow, counter flow and mixed flow; according to the installation method of atomizer, it can be divided into upper spray type and lower spray type; The structure can be divided into centrifugal type, pressure type and air flow type; according to whether the heating gas is circulated, it can be divided into open type, partial circulation type and closed type. 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.
From a process point of view, the solution includes selecting the right solvent, adding the excipients, and changing the process parameters. However, there is not much room for adjustment of these methods, so a fundamental solution must be sought from the perspective of the equipment. Experts at home and abroad have studied the problem of sticking and agglomeration during the drying process. It is believed that the main cause of sticking is the wall temperature.
There are three kinds of cases in the spray dryer: 1. The semi-wet material sticks to the wall: the reason is that the sprayed droplets have already contacted the wall before the surface is dried, thus sticking to the wall and sticking to the wall. Generally speaking, it is on the plane of the trajectory of the droplet sprayed by the atomizer, and the structure of the atomizer, the movement state of the hot air in the tower; 2. The hot-melt adhesion of the low-melting material: the reason is that the material is At a certain temperature, the melting point begins to melt and becomes sticky, and adheres to the wall; 3. The surface adhesion of the dry powder: the dry powder moves in a limited space and there will always be some impact on the wall, which is unavoidable. However, such a sticky wall is generally not thick, as long as it can be shaken by air blowing or tapping gently. Zui's simple solution is to polish the inner wall, which can solve this problem to some extent.
Here are 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. Changzhou Binda Dry Granulation Equipment Co., Ltd. specializes in the production of spray dryers. The company's quality policy: market-oriented, customer satisfaction as the purpose, continuous improvement, and advanced behavior.
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