The most comprehensive plate and frame filter press information

 

Mechanical filter press wastewater treatment operation and precautions

1. Tighten the filter plate: Turn on the power, start the motor, and tighten the filter plate of the filter press. Note that the number of filter plates should be checked before compressing the filter plates. They should meet the specified requirements. There should be no foreign matter between the sealing surfaces of the filter plates, and the filter cloth should be flat against the filter plates without wrinkles.

2. Pressure maintenance: Mechanical compression reaches the pressure of the filter press.

3. Feed filtration: After entering the pressure maintaining state, check the opening and closing status of each pipeline valve, and then start the feed pump after confirming that it is correct. The feed liquid enters each filter chamber through the feed hole on the thrust plate. Under the specified pressure Filter under pressure and gradually form a filter cake. During the feeding process, pay attention to the changes in the filtrate and feeding pressure. Note that the water level of the feed pump should be normal and the feeding process should be continuous to avoid clogging of the feed hole and causing pressure difference, which may lead to filter plate rupture. When the filtrate flows out very slowly and the filter cake pressure reaches more than 5 kg, turn off the feed pump.

4. Loosen the filter plate and remove the filter cake: turn on the power, start the motor, loosen the pressing plate, and remove the filter cake.

5. Clean and organize the filter cloth: Clean the filter cloth regularly. When cleaning and sorting the filter cloth, you should carefully check whether the filter cloth is damaged and whether the feed hole and liquid outlet hole are blocked. The feed port should be carefully checked every time when feeding to avoid pressure difference and damage to the filter plate.

Note: The water level and oil level of the feed pump change; the oil level of the filter press gearbox changes.

Use of plate and frame filter press

 Equipment installation and debugging

1. Design the embedded holes according to the foot dimensions provided by the supplier, and adopt the double grouting method.

2. Sufficient space should be left around the filter press to facilitate operation and maintenance.

3. The filter press should be placed horizontally on the floor, and the rear top plate should be fixed to the foundation with foot bolts. (Note: The foot bolts generally only fix the rear top plate, because the pull stem will bend downward to a certain extent due to the pressure of the plate and frame. When the filter press is working, the pull stem will be straightened, resulting in a small amount of displacement. If If both ends are fixed at the same time, the pressure may not be tight or the rack may be damaged.)

4. The material and specifications of the filter cloth are determined according to the filtered material, pressure and temperature. The appropriate filter cloth should be selected.

5. Arrange the plates and frames neatly on the frame as required, and arrange the processed filter cloth neatly on the filter plates. Pay attention to the correspondence between the feed holes and the rinsing holes between the filter plates.

6. Turn on the power and check whether it is normal. For mechanical transmission, check whether the forward and reverse rotation of the motor meets the requirements, whether the reduction box and the machine head oil cup are filled with oil, and whether the screw and gear lubricating oil are filled. Hydraulic transmission: Check whether the operating sound of the gear pump is normal, whether there is any leakage in the hydraulic system, and whether the piston rod moves in and out smoothly.

2. Operating procedures for plate and frame filter press

2.1. How to operate the filter press

(1) Pre-filtration inspection

1. Before operation, check the inlet and outlet pipelines, whether there are leaks or blockages in the connections, whether the pipelines, filter press frame and filter cloth are kept clean, and whether the liquid inlet pump and valves are normal.

2. Check whether the connecting parts of the frame, bolts and nuts are loose, and they should be adjusted and tightened at any time. Parts that move relative to each other must always be well lubricated. Check whether the oil level of the reducer and nut oil cup is in place, and whether the forward and reverse rotation of the motor is normal. 

(2) Preparing for filtering

1. Turn on the external power supply, press the button on the operation box to reverse the motor, move the middle top plate back to the appropriate position, and then press the stop button.

2. Hang the clean filter cloth on both sides of the filter plate and align the material holes. The filter cloth must be larger than the sealing surface of the filter plate. The cloth holes must not be larger than the tube holes. They must be smoothed without folding to avoid leakage. The plate and frame must be aligned neatly. The order of the rinse filter plates must not be misplaced.

3． Press the forward button on the operation box to make the middle top plate press the filter plate tightly. When a certain current is reached, press the stop button.

(3) Filtering

1. Open the filtrate outlet valve, start the feed pump and gradually open the feed valve to adjust the return valve. Depending on the filtration speed, the pressure gradually increases, generally not greater than 0.6MPa. At the beginning, the filtrate is often turbid, and then becomes clear. If there is a large leakage between the filter plates, the tightening force of the middle top plate can be appropriately increased. However, due to the capillary phenomenon of the filter cloth, a small amount of filtrate will still leak out. This is normal and can be collected and stored in the support basin.

2. Monitor the filtrate and if it is found to be turbid, the open flow type can close the valve and continue filtration. If there is undercurrent, the machine should be stopped and replaced with damaged filter cloth. When the material liquid is filtered or the filter residue in the frame is full and filtration cannot continue, it is the end of one filtration. .

(4) End of filtering

1. The feeding pump stops working and the feeding valve is closed.

2. When discharging slag, press the motor reverse button to retract the middle top plate.

4. Unload the filter residue and rinse the filter cloth, filter plate and filter frame, and stack them neatly to prevent the plates and frames from deforming. They can also be placed in the filter press one by one and tightened with a compression plate to prevent deformation. Wash the site and scrub the frame. , keep the rack and site clean, cut off the external power supply, and the entire filtering work is completed.

2.2 Filter press operating procedures

1. The number of filter plates placed on all specifications of filter presses must not be less than the number specified on the nameplate, and the compaction pressure, feed pressure, squeezing pressure and feed temperature must not exceed the range specified in the instructions. If the filter cloth is damaged, the hydraulic oil should be replaced in time. Under normal circumstances, the hydraulic oil should be replaced once every half a year. In dusty environments, it should be replaced once every 1-3 months and all hydraulic components such as oil cylinders and tanks should be cleaned.

2. The screw rod, screw nut, bearing, shaft chamber and hydraulic mechanical pulley shaft of the transmission part of the mechanical filter press should be filled with liquid lubricant 2-3 times per shift. It is strictly prohibited to wipe dry calcium base on the screw rod. Grease lubricant, it is strictly forbidden to start the tightening action again in the tightening state, and it is strictly forbidden to adjust the current relay parameters at will.

3. When the hydraulic filter press is working, no one is allowed to stay or pass behind the cylinder. Someone must supervise the operation when compressing or returning. Each hydraulic part must not be adjusted at will to prevent equipment damage or personal safety caused by out of control pressure.

4. The sealing surface of the filter plate must be clean and wrinkle-free. The filter plate should be vertical and neat with the main beam. It must not be moved forward or backward, otherwise the compression action must not be started. It is strictly forbidden to extend the head and limbs between the filter plates during the process of pulling the plates to unload slag. The air in the cylinder must be exhausted.

5. All filter plate inlets must be cleaned to avoid clogging and damaging the filter plate. The filter cloth should be cleaned in time.

6. The electrical control box must be kept dry, and it is prohibited to wash various electrical appliances with water. The filter press must have a grounding wire to prevent short circuit and leakage.

3. Equipment maintenance and upkeep

In order to better utilize and manage the plate and frame filter press, improve product quality, and extend the life of the equipment, daily maintenance and upkeep of the plate and frame filter press is an essential link, so the following points need to be done:

1. Always check whether the connecting parts of the plate and frame filter press are loose, and they should be tightened and adjusted in time.

2. Clean and replace the filter cloth of the plate and frame filter press frequently. When the work is completed, the residue should be cleaned up in time and should not dry into lumps on the plate and frame to prevent material leakage when used again. Clean water strips and drainage holes frequently to keep them clear.

3. The engine oil or hydraulic oil of the plate and frame filter press must be replaced frequently, and the rotating parts must be well lubricated.

4. If the filter press is not used for a long time, it should be oiled and sealed. The plates and frames should be stacked flatly in a ventilated and dry warehouse with a stacking height of no more than 2m to prevent bending and deformation.

Analysis of common faults of plate and frame filter press

The plate and frame filter press is a sludge treatment equipment in the sewage treatment system. Its function is to filter the sludge after sewage treatment to form large filter cakes (mud cakes) for removal. The plate and frame filter press consists of five major parts: filter plate, hydraulic system, filter press frame, filter plate transmission system and electrical system. The working principle of the plate and frame filter press is relatively simple. First, the plate and frame group is pressed by hydraulic force, and the precipitated sludge enters from the middle and is distributed between the filter cloths.

Due to the compression of the plate and frame, the sludge cannot escape. Under the high pressure of the screw pump and diaphragm pump, the moisture in the sludge seeps out of the filter cloth and flows into the return pipe, while the mud cake remains in the cavity. Afterwards, the plate and frame are relieved of pressure, the filter plate is pulled apart, and the mud cake falls by gravity and is pulled away by the car. Therefore, the filter press process is the last process in the sewage treatment process. The main parameters and data of the plate and frame filter press are: 125 plates and frames, which can be expanded to 150 (149 compartments), plate size 1300 × 1300mm, mud cake thickness 30mm, filtration area 297.6 m2, filtration pressure 16bar, maximum Closing pressure 368bar.

When the plate and frame filter press is compressed, the pressure is 368 bar, and the filtering pressure is 16 bar. During operation, the plate and frame continue to be compressed, and the water in the middle seeps out from the sludge medium. Due to the high pressure, the plate itself and the filter cloth are prone to appear Damaged or clogged. In addition, due to contamination with oily sludge, the transportation system often gets stuck or moves unsteadily.

1. Damage to the plate itself. The reasons for damage to the plate itself include:

1. When the sludge is too thick or dry blocks are left behind, it will cause the feed port to be blocked. At this time, there is no medium between the filter plates and only the pressure of the hydraulic system itself is left. At this time, the plates themselves are easily prone to being pressurized for a long time. cause damage.

2. When the feed is insufficient or the feed contains inappropriate solid particles, it will also cause excessive stress on the frame itself and cause damage.

3. If the outflow port is blocked by solids or the feed valve or outlet valve is closed during startup, the pressure will have nowhere to leak, causing damage.

4. When the filter plate is not cleaned cleanly, the medium may sometimes leak. Once leaked, small grooves will be washed out on the edges of the plate and frame. The large amount of leakage of the medium will cause the pressure to fail to rise and the mud cake to form. 

The repair techniques for filter plates are as follows:

After using the filter plate for several years, for some reason, some grooves were washed out at the corners. Once the groove marks appear, they will expand rapidly until they affect the formation of the filter cake. The filter cake becomes soft at first, then becomes semi-slurry, and finally the filter cake cannot be formed. Due to the special material of the filter plate, it is difficult to repair and can only be replaced with new ones, which results in high spare parts consumption. The specific repair methods are as follows:

Repair steps:

1. Clean the trench and if fresh noodles leak out, you can use a small saw blade to clean it.

2. Mix black and white repair agents in a ratio of 1:1

3. Apply the prepared repair agent to the groove, covering it slightly higher

4. Quickly put the filter cloth on, squeeze the filter plates together so that the repair agent and filter cloth stick together, and squeeze out the groove at the same time.

5. After extrusion for a period of time, the viscose will naturally form and no longer change, and it can be used normally.

2. Water seepage between boards and frames The main reasons for water seepage between boards and frames are:

1. Low hydraulic pressure

2. There are wrinkles in the filter cloth and holes in the filter cloth.

3. There are lumps on the sealing surface.

The treatment method for water seepage between plates and frames is relatively simple. Just increase the hydraulic pressure accordingly, replace the filter cloth, or use a nylon scraper to remove the lumps on the sealing surface.

3. The filter cake cannot be formed or the filter cake is uneven

There are many reasons why the filter cake is not formed or is uneven. Insufficient or too thin feed, or clogging can cause this phenomenon. It is necessary to carefully investigate the causes of these failures, finally find the exact problem, and then implement symptomatic treatment to solve the problem. The main solutions are: increase the supply, adjust the process, improve the supply, clean or replace the filter cloth, clean the blockage, clean the feed hole, clean the drainage hole, clean or replace the filter cloth, increase the pressure or pump power, Low pressure start, continuous boosting and other methods.

4. The filter plate is slow or easy to fall off. Sometimes due to excessive oil stains and stains on the guide rods, the filter plate may move slowly or even fall off. At this time, it is necessary to clean the guide rod in time and apply butter to ensure its lubricity. One thing to note is that it is strictly forbidden to apply thin oil on the guide rod, because the thin oil will easily fall off and make the bottom very slippery. Personnel operating and performing maintenance here may easily fall, causing personal injury.

5. Hydraulic system failure.

The hydraulic system of the plate and frame filter press mainly provides pressure. When the oil chamber A is filled with more oil, the piston moves to the left, pressing the filter plate to seal it. When the oil chamber B is filled with more oil, the piston moves to the right and the filter plate loosens. Due to the precision manufacturing, there are fewer hydraulic system failures, as long as you pay attention to daily maintenance. However, due to wear and tear, oil leakage will occur every year or so. At this time, the O-ring seal as shown in the figure must be repaired and replaced.

Common hydraulic faults include failure to maintain pressure and inappropriate hydraulic cylinder advancement. The main reasons for failure to maintain pressure include oil leakage, O-ring wear, and abnormal operation of the solenoid valve. Common solutions are to remove and inspect the valve, replace the O-ring, clean and inspect the solenoid valve, or replace the solenoid valve. The improper advancement of the hydraulic cylinder is obviously because the air is sealed inside. At this time, as long as the system evacuates air, it can usually be solved quickly.