The structure of rake dryer:

The whole device of the rake dryer is mainly composed of the rake tooth moving part, the vacuum part, the heating and capturing part. After the dried material is added from the feed port, the feed port is covered tightly, and hot water is passed into the shell jacket, and the vacuum pump is started. The main shaft of the rake dryer equipped with the tooth rake group is driven by the motor, and rotates forward and reverse at a speed of about 4r/min after being decelerated by the reducer. The material moves to both sides with the forward rotation of the tooth rake; when the tooth rake rotates in the reverse direction, the material converges from both sides to the middle. Because the material is indirectly heated by hot water on one side and evenly stirred by the rake teeth on the other side, the moisture in the material is vaporized. Under the action of the vacuum system, the vaporized water vapor passes through the dry dust collector, wet dust collector, and condenser, and is discharged from the vacuum pump outlet.

The dry dust collector captures the materials carried away by the vaporized water vapor and the water after the water vapor condenses. The wet dust collector further condenses the vaporized water vapor and captures the entrained solids. When drying harmful materials, the efficiency of the dust collector must be improved to avoid polluting the environment.

The condenser is mainly used to further condense the vaporized water vapor and discharge the condensed water to ensure that the vacuum pump of the dryer can maintain a high vacuum degree, which is conducive to better gasification of the internal and surface moisture of the material. The drying time of wet materials varies with the properties of the material, the different requirements for the moisture content of the inlet and outlet, the vacuum degree during operation, and the temperature of the drying medium. It usually takes more than ten hours.

1. Shell structure of rake dryer
The shell is composed of a horizontal steel cylinder with a welded heating outer jacket and a cover with flanges on both ends. The cover and the steel shell matching part and the filling part need to be cut, and the center line of the cover and the cylinder should differ by 5mm. When installing, the center line of the cover should be lower than the center line of the cylinder, so that when the rake teeth rotate, the material on the lower side of the shell can be easily unloaded. The entire shell is placed on two saddle supports. Note that there should be a certain amount of room for movement between one of the supports and the foundation to avoid stress caused by expansion of the equipment when the jacket is heated.
2. Rake tooth structure of rake dryer
The rake tooth device of the rake dryer is composed of two groups of rake teeth in the left and right directions, which are respectively sleeved on both sides of the transmission shaft at opposite angles. The rake tooth head of the rake dryer has a square hole that matches the transmission shaft. When assembled, the adjacent rake teeth differ by 90°. There are two shapes at the end of the rake teeth, one is flat and paddle-shaped, and the other is also flat but irregular. But they are all at a certain angle to the axis of the drive shaft (i.e. left and right). Paddle-shaped rake teeth are used in the middle of the equipment, and special-shaped rake teeth are used at the end of the dryer to fit the inner wall surface of the cover. The rake teeth are installed on one side, and the right-hand rake teeth are installed on the other side. So when the material is added, when the rake teeth rotate forward and reverse, the material can be moved to both sides and then to the middle, so that the material is evenly stirred. On the one hand, the material will not be overheated when it contacts the inner wall of the shell, and on the other hand, the material can be crushed, the gasification surface is increased, and the drying process is promoted.
In addition, in each of the four quadrants of the rake teeth, a seamless steel pipe with both ends closed and parallel to the main shaft is placed to knock the wall of the device, which has a certain effect on clearing and crushing materials. The rake teeth are generally made of cast steel. The drive shaft is subjected to torque and bending moment during operation. In addition to meeting certain strength requirements, the drive shaft must also have sufficient rigidity to avoid getting stuck with the inner surface of the shell. The drive shaft is generally made of model steel material.
3. The seal between the rake tooth device and the shell. From the drying principle of the rake drying machine, it can be known that the material is heated in the dryer, the moisture in the material is vaporized, and the vacuum device generates a high vacuum to extract the vaporized water vapor, which intensifies the escape of moisture inside the material and surface moisture. If the seal between the shaft and the shell is not good, the vacuum degree in the equipment will be greatly reduced; at the same time, the entry of cold air will reduce the temperature of the material in the equipment and affect the drying efficiency. The seal between the rake tooth device and the shell usually uses asbestos as filler, which is a simple and effective sealing structure. This sealing structure also presses the rake teeth together, reducing the wear on the end face of the rake teeth. In addition to the above type, the rake drying machine also has a jacket and a transmission shaft that pass water vapor, and the matching of the transmission shaft and the rake teeth.

Technical specification:

Note: The amount of water evaporation is related to the characteristics of the material and the hot air inlet and outlet temperatures. When the outlet temperature is 90℃, the water evaporation curve is shown in the figure above (for reference). As the product is constantly updated, the relevant parameters will be changed without prior notice.

Equipment Pictures: