There are many types of dryer, but spray dryer is the most widely used.
Spray dryer is easy to operate, excellent in performance and excellent in manufacturing, especially in meeting the requirements of GMP in pharmaceutical and food industries. It is welcomed by users in the pharmaceutical and food industries.
Spray dryere is especially suitable for drying and granulating of Chinese and Western medicines and food products. The granules have strong disintegration, good fluidity and instant solubility, and can be directly used for pressing tablets, irrigating capsules, making granules and solid beverages.
Spray dryer is widely used in chemical industry, light industry and food industry because it can be directly obtained from solution or suspension system with uniform powder products. Chemical industry is most commonly used in dyestuff industry. After years of efforts of engineers and technicians, spray drying technology has been relatively mature, and the determination of tower size also has a successful calculation method.
The spray dryer can atomize the dry liquid through the nebulizer into tiny droplets in the drying room and evaporate the water by direct contact and mixing with the hot gas in the drying medium, and then obtain the powder or granular products by gas solid separation and collection.
The raw material solution can be solution, emulsion, suspension, melt or paste. The drying medium can be air, nitrogen or superheated steam.
The main components of spray dryer consist of air heating system, raw material delivery system, atomizer, drying system, gas solid separation and collection system, control system, and special demand medium circulation mechanism.
Spray drying is widely used in drying of dyes. A drying method for removing moisture by atomizing dyes. It is suitable for drying all kinds of dyes. It can dry fine dyestuff powder, superfine powder, dust free powder and hollow granule.
It can be divided into three types according to the atomization mode of dyes:
(1) The air flow atomization uses compressed air or water vapor to atomize the material liquid;
(2) Pressure type atomization, high pressure pump is used to press the material liquid out of the nozzle at high speed to form mist;
(3) In rotary atomization, the feed liquid is added to the high-speed rotating disc (7000-28000r / min) in the atomizer, and the feed liquid is quickly thrown out to atomize. The third method has the advantages of good effect, short time and high labor productivity, which is favored by dye industry. Its disadvantages are large equipment investment and high energy consumption.
Advantages of spray dryer:
1. The drying process is very fast.
2. It can be dried into powder directly.
3. Easy to change drying conditions and adjust product quality standards.
4. Due to instantaneous evaporation, the equipment material selection requirements are not strict.
5. There is a certain negative pressure in the drying chamber to ensure the sanitary conditions in the production, avoid the dust flying in the workshop, and improve the product purity.
6. High production efficiency and few 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 volume of dryer.
8. the adjustment of spray dryer is convenient, and the operation conditions can be changed in a larger range to control product quality indicators, such as particle size distribution, moisture content, bioactivity, solubility, color, aroma, taste and so on.
Disadvantages of spray dryer:
1. The equipment is more complex, covers a large area and has a large investment.
2. The price of atomizer and powder recovery device is high.
3. More air is needed to increase the power consumption of blower and the capacity of recovery device.
4. Low thermal efficiency and high heat consumption.