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Introduction to filter presses Editorial Podcast

A filter press is a machine that applies mechanical force to one side of the filter medium to achieve filtration. The Shanghai plate filter press is suitable for liquid with less viscosity and less residue than 50% concentration for closed filtration to achieve purification, sterilization, clarification and other requirements of fine filtration and semi-fine filtration; the direct choice of microporous filter membrane can achieve the purpose of sterile filtration without filtering through microporous membrane filter.
Features Editor Podcast
Plate Filter Press
Plate Filter Press
The plate filter press is made of OCr19Ni9 high quality corrosion resistant stainless steel except for the matching motor, which is suitable for filtering various PH value acid and alkali solutions; this machine should be pressurized and closed filtering, with less filtering loss; good filtering quality and high efficiency. The filtering part is composed of nine layers of filter plates, with large filtering area and large circulation; and it can replace different filter membranes according to the requirements of different production processes (primary filtration, semi-precision filtration, and precision filtration) of the filtered solution, and the number of layers of filter plates can be appropriately reduced or enhanced according to the size of the user’s production flow to make it suitable for production needs, so this machine has the characteristics of being multi-purpose with a wide range of applications; the filter plates are in the shape of flat threaded mesh, with advanced structure and no This machine is equipped with a stainless steel infusion pump, which has a small motor and consumes less electricity. The machine is equipped with rubber wheels under the base, which is easy to operate and flexible for mobile use. [1]
Basic Structure Editor Podcast
(1) rack: the rack is the foundation part of the filter press, the two ends are the stop pushing plate and the pressing head, the beam on both sides will be the two evenly enforced, the beam is used to support the filter plate, the filter frame and the pressing plate. a. Stop pushing plate: it is connected with the support to sit one end of the filter press on the foundation, the middle of the stop pushing plate of the chamber filter press is the feeding hole, there are four holes at the four corners, the holes at the upper two corners are the washing liquid or pressing gas import, the lower two corners is the outlet (concealed flow structure or filtrate outlet) b. Pressing plate: used to press the filter plate and filter frame, the rollers on both sides are used to support the rolling of the pressing plate on the track of the beam. c. Beam: is a load-bearing member, according to the requirements of the use environment of anti-corrosion, it can be coated with hard PVC, polypropylene, stainless steel cladding or new anti-corrosion coating.
(2) Pressing mechanism: manual pressing, mechanical pressing, hydraulic pressing. a. Manual pressing: the screw type mechanical jack is used to push the pressing plate to press the filter plate. b. Mechanical pressing: the pressing mechanism consists of an electric motor (equipped with an advanced overload protector), a reducer, a gear payment, a screw and a fixed nut. When pressing, the motor is turning, driving the reducer and gear payment, making the filament rod rotate in the fixed nut, pushing the pressing plate to press the filter plate and filter frame. When the pressing force becomes bigger and bigger, the motor load current increases, when it reaches the current value set by the protector, the maximum pressing force is reached, the motor cuts off the power supply and stops rotating, because the filament rod and the fixed filament mother have a reliable self-locking spiral angle, it can reliably ensure the pressing state during the working process, when it is returned, the motor reverses, when the pressure block on the pressing plate touches the travel switch, it is returned to stop. c. Hydraulic pressing: The hydraulic pressing mechanism is composed of hydraulic station, cylinder, piston, piston rod and piston rod and pressing plate even.
(3) filtering mechanism: filtering mechanism consists of filter plate, filter frame, filter cloth and pressing diaphragm, both sides of the filter plate are covered by filter cloth, and when the pressing diaphragm needs to be configured, a set of filter plate is composed of diaphragm plate and side plate. The diaphragm plate is covered with rubber diaphragm on both sides of the substrate, the diaphragm is covered with filter cloth on the outside, and the side plate is the common filter plate. The solid particles are retained in the chamber because their particle size is larger than the pore size of the filter media, and the filtrate flows out from the outlet hole below the filter plate. When the filter cake needs to be pressed dry, in addition to the diaphragm press, compressed air or steam can also be used, through the washing port, airflow to wash away the water in the filter cake, in order to reduce the water content of the filter cake. [1]
Category Editor Podcast
In terms of the form of filter plate, there are chamber type and plate and frame type filter presses; in terms of the different orientation of the filter plate, there are vertical and horizontal; in terms of the different materials of the filter plate, there are plastic, rubber, cast iron, cast steel, carbon steel, stainless steel; in terms of whether the filter plate is equipped with rubber squeeze film, there are squeeze dewatering and non-squeeze dewatering; in terms of the different number of filter cloth surfaces of the filter plate configuration, there are single-sided dewatering and double-sided dewatering and so on. But no matter what kind of filter press, its working principle is firstly positive pressure strong pressure dewatering, also called into the slurry dewatering, that is, a certain number of filter plates in the role of strong mechanical force is closely arranged in a row, the filter plate surface and the filter plate surface between the formation of the filter chamber, filter materials in a strong positive pressure is sent into the filter chamber, into the filter chamber of the filter material solid part by the filter media (such as filter cloth) to retain the formation of filter cake, liquid part through the filter media and As the positive pressure increases, the solid-liquid separation becomes more complete, but the high positive pressure is not cost effective in terms of energy and cost. After the pulp dehydration, the filter press equipped with a rubber squeeze membrane, the compression medium (such as gas and water) enters the back of the squeeze membrane to push the squeeze membrane to further dehydrate the squeeze filter cake, called squeeze dehydration. After pulp dehydration or extrusion dehydration, compressed air enters the filter chamber on one side of the filter cake through the filter cake and carries liquid water from the other side of the filter cake through the filter cloth to discharge the filter chamber and dehydration, called wind-blown dehydration. If both sides of the filter chamber are covered with filter cloth, the liquid part can be discharged from the filter chamber through the filter cloth on both sides of the filter chamber, which is called double-sided dewatering of the filter chamber. After dewatering is completed, the mechanical compression force of the filter plate is lifted and the single piece is gradually pulled away from the filter plate and the filter chamber is opened separately for unloading the cake as a major work cycle is completed. Depending on the nature of the filter material, the filter press can be set up to feed pulp dewatering, extrusion dewatering, wind-blown dewatering or single or double-sided dewatering, with the aim of minimising the water content of the filter cake. The reason why the plate and frame filter press has flourished and been widely used in various industries is that its biggest advantage is positive pressure and high pressure dewatering, which is much larger than the pressure difference of the traditional vacuum filter, resulting in low water content of the filter cake, less energy consumption, less metal loss and clear and transparent filtrate. As early as more than ten years ago, some experts pointed out that the filter press is the only excellent equipment among all industrial filter machines that can ensure that the water content of the filter cake reaches less than 10% and can be used without adding flocculants. [1]
Working Principle Editor Podcast
First step of pressing
The whole machine must be checked before the operation of the filter press: check whether the filter cloth is folded or overlapped and whether the power supply has been connected properly. After the inspection, the press can be operated. Firstly, press the “Start” button and the oil pump will start to work, then press the “Press” button and the piston will push the pressing plate to press, when the pressing force reaches the adjusted high point pressure, the hydraulic system will automatically jump to a stop. [1]
Second feeding step
When the filter press is pressed, the feeding operation can be carried out: open the feeding pump and slowly open the feeding valve, the feeding pressure gradually rises to the normal pressure. At this time, observe the liquid discharge from the filter press and the leakage between the filter plates. After filtering for a period of time, the liquid discharge from the liquid discharge hole of the filter press gradually decreases, which means that the filter residue inside the filter chamber is gradually filling up, and when no liquid or only a very small amount of liquid is discharged from the liquid discharge hole, it proves that the filter residue inside the filter chamber has completely filled up to form the filter cake. If the filter cake needs to be washed or air dried, this can be done subsequently, if no washing or air drying is required, the cake can be discharged. [1]
Step 3 Washing or air-drying
Plate Filter Presses
Plate Filter Press
When the filter press is full of filter cake, turn off the feed pump and feed valve. Turn on the washing pump or air compressor and slowly open the inlet liquid or inlet air valve to wash or air dry the filter cake. After the operation is completed, close the washing liquid pump or air compressor and its valve, and the cake unloading operation can be carried out. The fourth step is to unload the cake: firstly, close the feed pump and the feed valve, the washing liquid or air inlet device and the valve, then press and hold the “release” button on the operation panel, the piston rod will drive the pressure plate back, after retreating to a suitable position, release the pressed “release” button and manually Pull the filter plate piece by piece to unload the filter cake, and at the same time clean up the filter slag stuck on the sealing surface to prevent the filter slag from being caught on the sealing surface to affect the sealing performance and produce leakage, so that one operation cycle is completed. [1]
Filter Press Method Editorial Podcast
A method of rapid filtration by plate filter press, characterized in that: when the water content in the filter residue is reduced to 70-90%, the press-in of the filter slurry is stopped and the filter residue inside the filter cloth is heated by heating and kept for 0.5-2 hours. The residual water in the filter sludge is vaporised and discharged, and the water content of the filter sludge is greatly reduced, leading to the automatic separation of the filter sludge from the filter cloth. When the filter plate is separated, the filter sludge wrapped between the filter cloth will automatically fall away from the filter cloth. This method not only shortens the time required to complete a cycle of filter press operation, but also facilitates the cleaning of the filter residue. The efficiency of the plate filter press is greatly improved. [1]
Related Research Editorial Podcast
Basic principles

  1. The basic working principle of the old type filter press is as follows.
    The filtering part of the filter press: 1) stopping and pushing plate, 2) filter plate, 3) pressing plate, 4) filter cloth composition
    The working principle is as follows: the pressing plate is pressed under the action of external force to form a cavity between the filter plates. The solid-liquid mixture is pumped into the chambers by the action of the infusion pump, and the liquid is discharged through the filter cloth and through the dark holes of the filter plate, while the solids are blocked by the filter cloth and gradually accumulate in the filter plate cavity to form the filter residue. In order to facilitate the collection and transport of the slag, and to avoid re-pollution of the environment, the slag is generally required to have a water content of 75% when it exits the filter plate.
    It can be seen that the volume of the filter chamber formed between the filter plates cannot be changed.
  2. Technical innovation point.
    The filter plate combination consists of three parts: the filter plate,china filter Press the rigid mat and the filter frame. The press filter presses each filter plate under the action of external force. When the infusion pump stops working, the rigid pad is removed and a space is formed between the filter plate and the filter frame, which will be closed under the action of external force. The lateral distance between the filter plate cavity will be reduced, i.e. the width of the rigid pad will be reduced. As the sludge in the filter plate chamber contains a certain water content, the reduction in the volume of the filter plate cavity will allow some of the water in the sludge to be squeezed out, i.e. the water content of the sludge will be reduced. [1]
    (1) Under the same working conditions (such as the power of the infusion pump and its working time, etc.) The plate filter press can use mechanical external force to reduce the volume of the filter plate cavity and squeeze out the water from the filter sludge, thus further reducing its water content.
    (2) The water content of the filter residue of any brand of filter press at home and abroad decreases as the operating time of the transfer pump increases. From the working time of the infusion pump – sludge water content characteristic curve can be seen, the infusion pump working time – sludge water content characteristic curve are very similar. In the first 3 hours after the pump starts working, the water content of the filter residue decreases significantly from 99% to 82% (a decrease of 17%), after which the pump works for about 5 hours, its water content will drop to about 75% (a decrease of only 7%). The plate filter press makes full use of the characteristics of the working time of the infusion pump and the characteristic curve of the water content of the filter residue, stops its work after the infusion pump has worked for 3 hours, removes the rigid pad and squeezes out part of the water in the filter residue with external force P3, so that the water content of the filter residue can be rapidly reduced to about 75%, which greatly shortens the time for the filter residue to come out of the filter plate and filter frame and improves the working efficiency. This greatly shortens the time for the sludge to exit the filter plate and frame and improves the efficiency. It is thus clear that the plate filter press is an energy-saving and highly efficient environmental protection product. [2]
    Technical keys
  3. Reasonable matching of the infusion pump and the filter press.
  4. Reasonable selection of different filter cloths for different filter residues. [2]
    Main technical indicators and conditions required
  5. The filter press can work continuously for 24 hours, changing from 2 shifts per day to 4 shifts per day.
  6. The water content of the filter residue is reduced from 99% to about 75% in 6 hours of work of the infusion pump. [2]
    Main equipment and operation management
    1、Main equipment
    Sewage lifting pump, dosing pump, mixer, air compressor, liquid transfer pump, filter press.
    2、Operation management
    The system has a high degree of automation, the level float controls the operation of the sewage lifting pump, dosing pump, mixer and lifting pump linkage, add acid, alkali pump controlled by pH meter operation, other equipment according to the system processing needs to run. The whole process of filter press work can be semi-automated. [2]
    Investment and benefit analysis
    1、Investment situation
    The total investment is 6 million yuan, of which, the equipment investment is 4 million yuan, the life of the main equipment is 15 years, and the operation cost is 1.36 million yuan/year.
    2、Economic benefit analysis
    (1) The whole filter press cycle can be shortened and the working efficiency can be improved by about 60%.
    (2) It can save energy about 37.5%, simple operation, easy maintenance and repair.
    (3) It can save about 43% of investment cost per year, and can recover the investment cost in about two years.
    (The service life of the filter press is 7 to 10 years)
    (4) Low water content of slag, easy to collect and transport, no secondary environmental pollution.
    3、Environmental benefit analysis
    Each year, the total copper discharge of pollutants can be reduced by 8767kg, total cyanide by 35609kg and COD value by 25748kg, which can greatly reduce the pollution of water environment, save water resources and avoid environmental disputes. [2]