There are many types of drying granulators, but spray drying granulators are widely used.
The spray dryer is designed on the basis of the same type of products imported from abroad in the 1980s after digestion, absorption and improvement. The spray dryer is welcomed by users in the pharmaceutical and food fields because of its simple operation, superior performance and excellent manufacturing, especially its ability to meet GMP requirements in the pharmaceutical and food industries. This equipment is particularly suitable for drying and granulating traditional Chinese and Western medicine, as well as food products. The resulting particles have strong disintegration, good fluidity, and good instant solubility. They can be directly used for tablet pressing, capsule filling, as granules and solid beverages.
Spray drying is still widely used in chemical industry, light industry, food industry and other industries due to its special advantage that it can directly produce powder products with uniform composition from solution or suspension system. Dye industry is widely used in chemical industry. Through the efforts of engineers and technicians in recent years, the spray drying technology has been relatively mature, and there are also successful calculation methods to determine the tower size.
Spray drying refers to the method of atomizing the liquid to be dried into tiny droplets in the drying room through the atomizer, and evaporating the water by directly contacting and mixing the hot gas of the drying medium with it, and then obtaining powder or granular products through gas-solid separation and collection.
The raw material liquid can be a solution, emulsion, or suspension, as well as a melt or paste. The drying medium can be air, nitrogen, or superheated water vapor.
The spray drying system is mainly composed of air heating system, feed liquid conveying system, atomizer, drying system, gas-solid separation and collection system, control system, media circulation mechanism with special requirements, etc.
Spray drying is a method of systematic technology applied to material drying. After atomizing the diluent in the drying room, the moisture rapidly vaporizes in contact with hot air, resulting in a dry product. This method can directly dry solutions and emulsions into powder or granular products, eliminating the need for evaporation, crushing, and other processes. Through mechanical action, the material that needs to be dried is dispersed into very fine mist like particles (increasing the evaporation area of water and accelerating the drying process), which come into contact with hot air and instantly remove most of the water, drying the solid substances in the material into powder.
Spray drying is characterized by fast heat transfer, rapid water evaporation, and short drying time. Besides, the product has good quality, crisp texture, and good solubility, which can improve the dissolution rate of some preparations and is suitable for heat sensitivity. In addition, spray drying can also be used to prepare microcapsules.
Spray drying is a widely used method for dye drying. A drying method for removing moisture by atomizing dyes. Suitable for drying various dyes. It can dry fine dye powder, ultrafine powder, dust-free powder, and hollow granules. According to the methods of dye atomization, it can be divided into three categories: (1) Airflow atomization, which uses compressed air or water vapor to atomize the material liquid; (2) Pressure atomization, using a high-pressure pump to rapidly press the material liquid out of the nozzle, forming a mist; (3) Rotating atomization involves adding the liquid material to a high-speed rotating disc (7000-28000r/min) inside the atomizer, rapidly ejecting the liquid material and atomizing it. The third method has good results, short time, high labor productivity, and is favored by the dye industry. Its disadvantages are high equipment investment and high energy consumption.
advantage
The drying process is very rapid.
2. It can be directly dried into powder.
3. Easy to change drying conditions and adjust product quality standards.
4. Due to instantaneous evaporation, the selection of equipment materials is not strictly required.
5. The drying room has a certain negative pressure, ensuring hygiene conditions during production, avoiding dust from flying in the workshop, and improving product purity.
6. High production efficiency with fewer operators.
7. Large production capacity and high product quality. The amount of spray per hour can reach several hundred tons, which is one of the larger capacity of the dryer.
8. The spray dryer is easy to adjust, and the operating conditions can be changed in a large range to control the product quality indicators, such as particle size distribution, moisture content, biological activity, solubility, color, aroma, taste, etc. [1]
shortcoming
1. The equipment is complex, occupies a large area, and requires a large initial investment.
2. The atomizer and powder recovery device are relatively expensive.
3. A large amount of air is required to increase the electrical energy consumption of the blower and the capacity of the recovery device.
4. Low thermal efficiency and high heat consumption.
