Working Principle of The Vibrating Fluidized Ded Dryer

Working Principle of The Vibrating Fluidized Ded Dryer

1.1 Type and structure of Vibration FBD Dryer

There are generally two types of vibrating fluidized bed dryers. 

One type is driven by a vibrating motor directly installed on the fluidized bed, including horizontal rectangular and vertical circular type, which is characterized by a simple fluidized bed structure, easy installation, and low cost; 

The other type is a box type exciter that separates the vibration part from the motor and is fixed at one end of the fluidized bed, which is a plate spring type. The vibration and transmission mechanism is complex, and the cost is high. It is generally used in large-sized fluidized bed dryers, with stable operation and uniform fluidization state. 

At present, the rubber industry generally uses horizontal rectangular cross-section vibrating fluidized bed dryers. The structure of a horizontal rectangular vibrating fluidized bed dryer is shown in Figure 1. It consists of a shell, distribution plate, vibrator (including vibration motor and isolation spring), as well as a hot and cold air system. 

A vibrator generally consists of two eccentric motors that rotate in opposite directions, known as a self synchronous dual axis inertial linear vibrator. The hot air enters from the bottom to top of the perforated distribution plate, and the material enters from the rear to the top. The material is fluidized in the fluidized bed by hot air and vibration, while undergoing heat and mass exchange. The dried material is cooled and transported by vibration to the discharge port, and the cold and hot air is discharged from the exhaust port on the upper part of the shell.

1.2 Characteristics

When drying granular materials in a normal regular fluidized bed, the following problems may occur: 

when the particle size is small, it forms a channel or dead bed, and when the particle distribution range is large, the entrainment can be quite severe; 

Due to the reverse mixing of particles, the retention time of materials in the machine varies, resulting in uneven moisture content of dried particles; 

When the humidity of the material is high, big size of agglomeration may occur, leading to deterioration of fluidization.

The vibrating fluidized bed from Taizhou Telang Machinery Equipment Manufacturing company is a successful improvement of a conventional fluidized bed by applying vibration to it, overcoming the aforementioned shortcomings of conventional fluidized beds. 

Compared with ordinary fluidized bed dryers, vibrating fluidized bed from Taizhou Telang Machinery Equipment Manufacturing company have the following advantages:

(1) In a regular fluidized bed, the fluidization of materials is completely achieved by airflow, while in a vibrating fluidized bed, fluidization and transportation are mainly achieved by vibration. The material exhibits an ideal fluidized state under the dual action of excitation force and hot air with a certain pressure, allowing for full contact between the material and the hot air.

(2) Due to the addition of vibration, the small fluidization speed of the material is reduced, leading to early occurrence of fluidization phenomena, especially when the granular material near the bottom layer of the gas distribution plate begins to fluidize, which is beneficial for eliminating wall phenomena and improving fluidization quality.

(3) The hot air entering the dryer is mainly used for heat and mass transfer during the drying process. By adopting a higher inlet air temperature and increasing the thickness of the material layer, higher thermal efficiency can be achieved. The thermal efficiency of a general vibrating fluidized bed dryer ranges from 30% to 60%. Therefore, the air volume is greatly reduced, only 20% to 30% of the air volume of ordinary fluidized bed dryers. The load of the fine powder recovery system is reduced, and the phenomenon of fine powder entrainment is generally reduced. The supporting heat source, fan, cyclone separator and other specifications are also reduced accordingly, and the energy-saving effect is remarkable.

(4) A vibrating fluidized bed can dry materials with a wide particle distribution and a relatively uniform residence time; It can also dry materials with viscosity or thermoplastic properties, reducing the requirements for material uniformity and regularity, making it easy to obtain