Selection and working principle of centrifugal dehydrator

Selection and working principle of centrifugal sludge dewatering machine:
The centrifugal dewatering machine is mainly composed of transfer and a screw conveyor with a hollow shaft. After the sludge is sent into the drum by the hollow shaft, it is immediately thrown into the cavity of the drum under the action of the centrifugal force generated by the high-speed rotation. The sludge particles have a large specific gravity, and the resulting centrifugal force is also large, and they are thrown onto the inner wall of the hub to form a solid layer; the water density is low, and the centrifugal force is small, and only a liquid layer is generated inside the solid layer. The sludge in the solid layer is slowly driven by the screw conveyor to be transported to the conical end of the transfer, and is continuously discharged through the outlet around the transfer. The liquid is discharged from the weir to the outside of the transfer after being collected and discharged out of the dehydrator.
The more critical part of the centrifugal dehydrator is the rotating hub. The larger the diameter of the rotating hub, the greater the dehydration processing capacity, but the manufacturing and operating costs are quite high, which is very uneconomical. The longer the reprinting length, the higher the solid content of the sludge, but too long reprinting will reduce the cost performance. During use, the speed of reloading is an important control parameter. Controlling the speed of the rotor hub can not only obtain a higher solid content rate but also reduce energy consumption.

The key to the operation of the heart dehydrator. Currently, low-speed centrifugal dehydrators are mostly used. When selecting the centrifugal dewatering machine, because the outer edge of the runner or spiral is very easy to wear, there are special requirements for its material. Most of the spiral outer edges of new centrifugal dehydrators are made into assembly blocks for easy replacement. The material of the assembly block is generally tungsten carbide, which is expensive.
The centrifugal dehydrator has the disadvantages of large noise, high energy consumption, and low processing capacity. There are only a few domestic manufacturers that can produce small centrifugal dewatering machines. If you choose large centrifugal dewatering machines, you can only rely on imports, which will increase engineering investment. At the same time, centrifugal dewatering machines are greatly affected by the fluctuation of sludge load. The quality of the operating personnel is relatively high, so the centrifugal dehydration process is not used in general sewage treatment plants. However, in recent years, with the advancement of science and technology, the dewatering technology of centrifugal dewatering machines has made great progress abroad. For example, the screw centrifugal dewatering machine produced by Alfa Layal Company in Sweden has a solid content of mud cake of more than 30%, and The operation is carried out in a fully enclosed environment. There is no sludge or sewage around the dehydrator, and there is no foul smell, which can greatly improve the working environment of the operators, so it is favored by the industry.

The belt filter press dewatering machine consists of two tensioned filter belts entraining the sludge layer, passing through a series of regularly arranged roller cylinders in an S shape, and relying on the tension of the filter belt itself to form the squeezing and pressing of the sludge layer. Shearing force squeezes out the capillary water in the sludge layer to obtain a mud cake with a higher solid content, thereby realizing sludge dewatering.
The general belt filter press dehydrator is composed of a filter belt, a roller press cylinder, a filter belt tensioning system, a filter belt deviation adjustment system, a filter belt washing system and a filter belt drive system. When making model selection, the following aspects should be considered:
(L) Filter belt. It is required to have high tensile strength, tortuous resistance, acid and alkali resistance, temperature change resistance, etc. At the same time, the specific properties of the sludge should be considered, and a suitable weave texture should be selected to make the filter belt have good air permeability and pollution resistance. The interception performance of mud particles.

(2) Deviation adjustment system of roller pressing cylinder. It is usually done by pneumatic device.
(3) The tension system of the filter belt. It is generally controlled by a pneumatic system. The tension of the filter belt is generally controlled at 0.3-0.7MPa, and the commonly used value is 0.5MPa.
(4) Belt speed control. Different types of sludge have different requirements for belt speed. That is, there is a better belt speed control range for any particular sludge. Within this range, the dewatering system can not only guarantee a certain processing capacity, but also Can get high-quality mud cakes.
The belt filter press dehydrator is less affected by the fluctuation of the sludge load, and also has the characteristics of low sludge water content, stable work and low consumption, relatively simple management and control, and low requirements for the quality of operating personnel. At the same time, because the belt filter press dehydrator entered the country earlier, a considerable number of manufacturers can produce this equipment. When making decisions on sewage treatment projects, belt filter presses can be used to reduce project investment. At present, most of the newly built sewage treatment plants in China use belt filter press dehydrators. For example, the five dehydrators of the first phase of the Beijing Gaobeidian Sewage Treatment Plant are all belt filter press dehydrators, with their own, roller presses, and filter inputs. Since the operation has been in good condition, this model was still used in the selection of the second phase equipment.

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