In recent years, Multi-disc vacuum filter has become more and more popular, because of the problems of resources and the environment have aroused popular concerns in the world. Especially for the paper-making enterprises, it is pretty vital for them to survive. Using the mode of the closed water can not only save water and recycle the fibers and the fillings, but also reduce production cost and lower the environment pollution. Multi-disc vacuum filter has the advantages of large production, simple operation and low energy consumption, which not only can be used for the treatment of white water recycle and other aspects, but also can be used as slurry concentrating equipment in the pulping and papermaking process.
Structure and working principle of multi-disc vacuum filter
Multi-disc vacuum filter is mainly composed of tank body, main shaft, filter plate, distribution valve, stripping device, flushing device, net washing device, transmission device, discharging device and the other parts. In use of vacuum filtration as the driving force, it can recycle the fibers and fillings during the treatment process of white water down from the copper wire net.
- when the main shaft rotates counterclockwise and makes the filter plate come to the position below the liquid level, the fan-shaped plate comes into the air filtration area. Under the static pressure, tank liquid through the filtering net will be expelled after passing main shaft and the air filtration area of distribution valve.
- Main shaft continues to rotate into the vacuum filter, the fan-shaped plate enters vacuum filtration area, the liquid in the tank goes through the filtering net and forms filter cake. At the early stage, the cake is thin, some fine fibers and fillings passes the filtering net together with filtering liquid, forming turbid filtrate. With the cake is getting thicker gradually, the fine fibers and fillings will be stopped by then, forming clear filtrate. The turbid filtrate and clear filtrate respectively flow into the different pools through barometric legs.
- As the fan-shaped plate rotates out of the liquid, vacuum doesn’t immediately disappear, still making the dehydration process for filtering layers of the filtering net. The liquid concentration is increased continuously.
- As the main shaft is continuously kept rotating, vacuum disappears, the fan-shaped plate enters the stripping zone. Then the stripping nozzles on both sides of the filtering discs begin to spray out the fan-shaped flushing water and make filtering layers directly send into receiving hopper. In final, it will be rushed and outlet after liquid dilution by flushing water pipe.
- When the filtering discs rotate to the net washing area, the swinging nozzles of net washing spray water to clean the net and recover the filtration capacity, which will make the equipment smoothly enter the next filtration cycle. With the continuous rotation of the filtering discs, the fan-shaped plate is in different working intervals in fact to ensure to make continuous white water get into the clear filtrate and recover fine fibers and fillings.
Operations of multi-disc vacuum filter
- Check before starting
- Check whether the electrical devices and auto-controlled instruments are normal or not.
- Check whether there are foreign bodies in the tank body or not.
- Check whether the pipes and the equipments leak or not.
- Check whether the clean filtrate pool is full and the liquid levels of other tanks are normal or not.
- Check whether the gap between receiving plates and filtering discs is appropriate or not.
- Starting program
Start control instrument and check level alarm indicator; turn the motor of filtering discs to manual gear and start the motor to make its speed from 0 to 1rpm; start stripping device or net washing pump, and observe whether water running is normal; open the white water pump, and when water reaches normal level, the alarm light is out. With the rise of liquid level and the rotation of the filtering discs, vacuum state is finished in barometric legs, the pulp layers appear on the filtering discs. Then open the water valve of stripping device and start turbid filtering pump and clean filtering pump, start a propeller motor, and change manual gear to the automatic gear. So the filter will go in normal working condition.
- Shutdown program
Close white water pump and pre-pulp hanging pump, when the liquid level of the filter is below the lowest limitation, the alarm indicator light is on. Close the turbid and clean filtrate pumps as no pulp layer exists, and close the stripping valve, close the discharging screw motor, open the drain valve until the tank is empty. Maintain the state of net washing for 10-15mins, and then close the filter and automatic control system. Finally, clean the tank of the filter, close the drain hole. .
- Emergency shutdown
When the fan-shaped plates are off or other serious malfunction occur, we should shut down the motor of the filtering discs and then close the other procedures.
Attentions when using multi-disc vacuum filter
- We should do the regular cleaning for the filter and replace the filtering net.
- In the production process, we should pay attention to strengthen the equipment inspection. Once the problems are found, we must solve them immediately.
- When the fan-shaped plate is installed, it is necessary for us to make the filtering plate composed of the fan-shaped plates keep in the same plane to ensure the quality of stripping pulp.