When the plate and frame
Filter Press filters different materials or the same material, due to different moisture content and even temperature, the filtration effect (speed, moisture content) may be different. Some materials even need to add filter aids before filtering, such as Flocculant, calcium carbide slag, etc., to adjust the filtration characteristics of the material. So the filter cakes will not be exactly the same.
Before filtration, the filter cloth and filter plate should be checked. If washing or air blowing is required, the washing plate, non-washing plate and washing hole should be checked, and the blowing hole should be checked to see if it is clear. Is the pressing force sufficient? (1) Open the filtrate outlet valve, start the feed pump, and gradually increase the feed valve. Depending on the filtration speed and filtration time, the filtration pressure can be gradually increased, generally not more than 0.6Mpa (plate and frame type not more than 0.4Mpa) at the beginning The filtrate may be turbid during filtration. This is because the material has not formed a pre-coating on the filter cloth and can continue to be used. It will clear up naturally later. If there is large leakage between the filter plates, the pressing force can be appropriately increased. Due to the capillary phenomenon of the filter cloth, it is normal for a small amount of filtrate to seep out.
(2) Monitor the filtrate. If turbid liquid is found in the open flow type, close the turbid water type. In the underflow type, stop filtration, check the filter cloth and repair or replace it.
(3) If a pneumatic diaphragm pump is used, the pressure reducing valve can be adjusted to set the filtration pressure at one time, without human operation during the filtration process. If a feed pump such as a screw pump is used, not only must a return system be installed, but the size of the return valve must be adjusted at any time according to changes in filter pressure to control the filter pressure. Someone needs to operate it, otherwise the equipment will be damaged.
(4) When the filtration pressure is large and the water output is small, the filtration can be regarded as completed and the pressing plate is returned. If the moisture content of the filter cake is found to be high, the pressing plate can be closed to continue filtration.
(5) If the filtration time is too long or the filter cake cannot be formed, consideration should be given to reducing the hydration rate of the material, such as increasing the sedimentation time, adding a concentration sedimentation tank, or adding flocculants and filter aids (quicklime, diatom perlite), replacing the filter media, etc. Solution. .
(6) If the filter cake needs to be flushed, close the water outlet on the washing plate with open flow, close the feed valve, open the washing water valve, and discharge water for flushing. The pressure of the flushing water is generally not greater than the rated filtration pressure of the equipment, and the flushing time should be It depends on the flushing effect. If the flushing effect is not satisfactory at one time, it can be flushed several times during the filtration process.
(7) In order to reduce the moisture content of the filter cake, the compressed air drying method can be used. The method is the same as the flushing method. The method of air intake through the feed hole or the use of a diaphragm filter press can also be used.
The hydraulic pressing mechanism of the filter press consists of a hydraulic station, a cylinder, a piston, a piston rod, and a Hafland card hydraulic station that connects the piston rod and the pressing plate. The structure of the hydraulic station consists of a motor, an oil pump, and a relief valve (for regulating pressure). Directional valve, pressure gauge, oil line, oil tank.
Filtration method: The way the filtrate flows out is divided into open flow filtration and undercurrent filtration. For open-flow filtration, the outlet hole at the bottom of each filter plate is equipped with a water nozzle, and the filtrate flows out of the water nozzle intuitively. In underflow filtration, there is a liquid outlet hole under each filter plate. The liquid outlet holes of several filter plates are connected to form a liquid outlet channel, which is discharged through a pipe connected to the liquid outlet holes under the thrust plate.
Washing method: When the filter cake needs to be washed, sometimes there is one-way washing and two-way washing, and undercurrent one-way washing and two-way washing.
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