Summary of product details of high-speed centrifugal spray dryer

The principle of high-speed Centrifugal Spray Dryer

The high-speed centrifugal Spray Dryer disperses the materials to be dried into very fine mist-like particles through mechanical action, (increases the area of water evaporation and accelerates the drying process) and contacts with hot air to remove most of the water in an instant. , to dry the solid matter in the material into powder.

Centrifugal rotary atomizer, the material liquid is added into the atomizer and rotated at a high speed (7000-28000r/min), and the material liquid is quickly thrown out and atomized. The hot air flows in the same direction. After drying, most of the finished products are discharged from the bottom, and the moist air is discharged into the atmosphere after dust removal.

Features of high-speed centrifugal spray Dryer

1. Fast drying speed. After the material liquid is sprayed by centrifugal spray, the surface area is greatly increased. In the high-temperature airflow, 95%-98% of the water can be evaporated instantly. The drying time is only a few seconds, and the labor productivity is high.

2. Although the temperature of the hot air is high, because the hot air enters the drying chamber and immediately contacts the spray droplets, the indoor temperature drops sharply, and the wet bulb temperature of the material remains basically unchanged, so it is also suitable for drying heat-sensitive materials.

3. The solution and emulsion can be directly dried into powder or granular products, and the processes such as evaporation and pulverization can be omitted. Suitable for heat-sensitive drugs, can be used to prepare microcapsules

4. The spray-dried finished product has good product quality, crisp texture and good solubility, which can improve the dissolution rate of some preparations and is suitable for heat-sensitive drugs.

5. The drying room has a certain negative pressure, which ensures the sanitary conditions in the production, avoids dust flying in the workshop, and improves the product purity.

6. High production efficiency and few operators.

7. Large production capacity and high product quality. It is one of the larger ones that the dryer handles the liquid.

8. The spray dryer is easy to adjust, and the operating conditions can be changed in a wide range to control the quality indicators of the product, such as particle size distribution, moisture content, biological activity, solubility, color, aroma, taste, etc.

Advantages of high-speed centrifugal spray dryer

Some plants lose their nutrients due to high temperature. For these plants, freeze-drying is an effective method of concentration preservation. However, some plants do need a certain temperature to remove toxicity. For these plants, spray drying technology is It couldn't be more ideal. In the case of soybeans, the concentration process requires a certain temperature to remove substances called trypsin inhibitors (which hinder digestion and break down proteins).

Often the last step in the manufacture of a product, spray drying is the process of changing a substance from a liquid to a powder through continuous spraying, mixing and drying. Among the many technologies for storing food, spray drying has its unique advantages. Because the temperature of this technology is not very high after the material is contacted, it can effectively retain the taste, color and nutrition of the food while removing microbial contamination.

Spray drying is commonly used to remove moisture from raw materials. In addition, it has many other uses, such as: changing the size, shape or density of substances, it can assist in the addition of other ingredients during the production process, and help to produce products with the most stringent quality standards.

The actual process of spray drying is divided into several steps: First, the liquid product is fed into the atomizer, and a high-speed rotating wheel in the atomizer atomizes the liquid, so that the product becomes a solid-liquid mixture of fine particles. Spray drying has the characteristics of fast heat transfer, rapid water evaporation, and short drying time, and the product quality is good, the texture is crisp, and the solubility is good. It can improve the dissolution rate of some preparations, and is suitable for heat-sensitive drugs. In addition, spray drying also Can be used to prepare microcapsules.

The mechanism of action of high-speed centrifugal spray dryer

(1) Pressure spray drying method:

①Principle: Using a high-pressure pump, at a pressure of 70-200 atmospheres, the material is passed through an atomizer (spray gun), and aggregated into mist-like particles of 10-200um, which are in direct contact with hot air for heat exchange, and drying is completed in a short time.

②Pressure spray atomization device: M-type and S-type, with a guide groove that makes the liquid flow rotate. The axis of the M-type guide groove is perpendicular to the nozzle axis and does not intersect with it; the axis of the S-type guide groove forms a certain angle with the horizontal. The purpose is to try to increase the turbulence of the solution when spraying.

(2) Centrifugal spray drying method:

①Principle: The centrifugal force is applied to the solution by a high-speed rotating disk in the horizontal direction, so that it can be thrown out at a high speed to form films, filaments or tiny droplets. The radial acceleration generated by centrifugal force has a spiral trajectory. After the liquid is thrown from the disk along this spiral line, it is dispersed into very small droplets. At the same time, the droplets are driven by their own gravity and hot wind speed. Instead, it falls in a spiral, due to the different sizes of the sprayed particles. Therefore, their flying distances are also different, so the particles falling at different distances form a cylinder symmetrical to the center of the rotation axis.

②Requirements for obtaining more uniform droplets: a. Reduce the vibration when the disc rotates b. The amount of liquid entering the disc is kept constant in unit time c. The surface of the disc is smooth and smooth d. The circumferential speed of the disc should not be too small, rmin = 60m/s, if the milk (100-160m/s) is less than 60m/s, the spray droplets are not uniform, and the spray distance seems to be mainly composed of a group of droplets and a group of fine droplets sinking near the disc, and increases with the rotation speed and decrease.

③Structure of centrifugal sprayer: Requirements: Calculate the diameter of the atomizing tower, so that the solution can reach high speed, spray evenly, firm structure, light weight, simple, no dead angle, easy to dismantle and wash, and have greater productivity.

Disadvantages of high-speed centrifugal spray dryer

1. The equipment is more complex, covers a large area, and requires a large investment.

2. Atomizer and powder recovery device are expensive.

3. A large amount of air is required, which increases the power consumption of the blower and the capacity of the recovery device.

4. The thermal efficiency is not high and the heat consumption is large.

Operational Requirements

1. The parts in contact with the product must be easy to clean;

2. There should be measures to prevent coke powder to prevent hot air from generating eddy currents and countercurrents;

3. Prevent the air from carrying impurities into the product;

4. Equipped with temperature and pressure indicating recorder device to facilitate inspection of production operation;

5. Dust recovery device with high recovery rate;

6. The powder should be quickly cooled to improve solubility and instant solubility;

7. Drying indoor temperature and exhaust air temperature are not allowed to exceed 100 °C to ensure safety and quality;

8. When spraying, the concentrated milk droplets are evenly contacted with the hot air to improve thermal efficiency;

9. Minimize sticking to the wall for viscous substances, and configure a cold wall device if necessary.