Overview Of Cyclone Dispersers For Drying Ovens

Currently, cyclone separators are widely used in convection drying systems in the drying equipment market, serving as an important piece of equipment for separating particulate matter from gases. Cyclone separators have a simple structure and are easy to manufacture. With proper design and manufacturing, high separation efficiency can be achieved. They can directly separate gases with high dust content, and the pressure loss is relatively small. They have no moving parts, making them durable. Except for wear on the inner wall of the cyclone separator caused by abrasive materials or the adhesion of fine powder, there are no other disadvantages.
Under normal circumstances, theoretically, a cyclone separator can capture particles larger than 5 μm, with a separation efficiency of over 90%. However, in actual production operations, the separation efficiency often decreases due to poor manufacturing, improper installation and use, or imperfect operation and management. It is usually only 50% to 80%, sometimes even lower.
A cyclone separator is also called a centrifugal separator. It utilizes the centrifugal force generated when a gas stream containing fine powder rotates to separate the fine powder from the gas.
Strictly speaking, the flow conditions of the gas in the cyclone separator are quite complex. Due to the agglomeration and dispersion of fine powder, the rebound effect of the separator wall on the fine powder, and the friction between particles, the separation mechanism is very complex, and theoretical research has never stopped.
After the gas stream containing fine powder enters the cyclone separator, it rotates along the inner wall while descending. As it reaches the conical section, the radius of rotation decreases, and according to the law of conservation of momentum, the rotational speed gradually increases, and the particles in the gas stream are subjected to greater centrifugal force. Because the separation velocity generated by centrifugal force is hundreds or even thousands of times greater than the settling velocity under gravity, the fine powder is separated from the rotating gas stream and falls along the wall of the cyclone separator. The gas flow begins to reverse near the bottom of the conical section, gradually rotates upwards in the central part, and finally is discharged from the riser pipe.
The smaller the diameter of the cyclone separator, the greater the inlet velocity, and the more rotations, the smaller the separated particle size. For real-world cyclone separators, due to airflow disturbances, friction with the wall, uneven particle distribution, particle-wall rebound effects, and the influence of particle shape, the critical particle size of the separator is not very accurate, and some fine particles will be mixed into the separated material.
The pressure drop of a cyclone separator is also an important performance indicator, usually proportional to the square of the gas inlet velocity, which can be expressed by the following formula:
The separation efficiency of a cyclone separator is a very important technical indicator. The particles in the fine powder gas are usually composed of particles of varying sizes. In separation technology, dispersibility is often used to reflect the particle size distribution. Dispersibility is the mass percentage of various particle sizes in the fine powder.
Practice has shown that the separation efficiency is not only related to the structure and operating conditions of the separator, but also varies with the particle size distribution. For the same equipment under similar operating conditions, different particle size distributions result in different overall efficiencies. Therefore, in separation technology, particle size distribution is used to determine the separation efficiency of the separator, which is the classification efficiency. This represents the separation efficiency of the separator for a certain particle size range of powder.
When dealing with a large volume of material, using a single cyclone separator of excessive size tends to reduce efficiency. Several small-diameter cyclone separators can be connected in parallel to form a cyclone separator group. Reducing the diameter of the cyclone separator will increase the centrifugal force and particle settling velocity.