What is a Filter Press?

Function:

to extract solid from mixed liquid, to separate solid and liquid.

Product Category:

1. Classification of filtration methods: chamber filter press, membrane filter press, plate and frame filter press.

2, structure classification: suspension filter press and belt filter press.

3. pressure type classification: manual pressing, hydraulic pressing, mechanical pressing.

Science used:

Physical properties of solids and liquids.

History:

The first filter press equipment appeared in the early 18th century, is used for chemical industry production.

Scope of use:

pharmaceutical, chemical, standard parts, pharmaceutical, metallurgy, non-standard screws, dyes, food, brewing, ceramics, oil refining, sewage treatment and other environmental protection industries.

Model performance parameters:

Filter area (square meters)

Filter plate Dimensions (mm)

Filter plate thickness (mm)

Filter cake thickness (mm)

Number of filter chambers Theoretical volume (L), (m³)

Overall dimensions (L x W x H)(mm)

Foundation dimensions (mm)

Filter chamber working pressure (MPa)

Motor power (KW)

Overall weight (KG)

Filter plate performance

Filter plate structure:

plate frame Type, chamber filter plate

Filter material:

stainless steel, cast iron, rubber, reinforced polypropylene (plastic), polymer PE, etc

Other properties:

acid and alkali resistance, filtration temperature (℃), filtration pressure (MPa)

Function configuration:

manual pressing, motor pressing, automatic hydraulic pressing, automatic pressure holding, electrical control/computer program control, automatic drawing plate, automatic liquid turning plate, etc.

Feeding mode :

middle feeding, Angle feeding, middle and upper feeding, upper and outer feeding.

liquid outlet mode:

Bright outflow liquid, undercurrent outflow liquid.

Components of filter press:

The frame is the basic part of the filter press, both ends are thrust plate and compression head, the two sides of the beam will be attached to the beam to support the filter plate, filter frame and compression plate.To meet advanced hygienic requirements, the racks are covered with stainless steel.Package stainless steel technology for reference, its quality can meet the needs of European customers.

Thrust plate:

it is connected with the support and one end of the filter press is located on the foundation. The thrust plate of the box filter press is in the middle of the feed Holes, four corners and four holes, the upper two corners of the hole is the inlet of the washing liquid or pressing gas, the lower two corners of the hole is the outlet (dark flow structure or filtrate outlet)

compression plate:

to press the filter plate filter frame, rollers on both sides to support the compression plate rolling on the beam track.

girder:

load-bearing components, according to the requirements of the use of environmental corrosion, can choose hard polyvinyl chloride, polypropylene, stainless steel coating or new anti-corrosion coating coating.

Pressing mechanism:

manual pressing
mechanical pressing
hydraulic pressing.

1, manual pressing: screw mechanical jack to push the pressing plate to press the filter plate.
2, mechanical compaction: compaction mechanism by motor (equipped with advanced overload protector) reducer, gear, screw and fixed Nut composition.When pressing, the motor turns forward to drive the reducer and gear to make the screw turn in the fixed screw, and push the pressing plate to press the filter plate and filter frame.When the pressure force is more and more big, the motor load current increases, when the big to protector set current value, maximum clamping force, motor to cut off the power supply, stop running, because of the wire rod and the fixed wire mother have reliable self-locking spiral Angle, can reliably guarantee the state of compression in the process of work, to return, motor reversal, when the weight for the hold-down plate, contact to switch back to stop.

3.Hydraulic pressure: hydraulic pressure mechanism is consists of hydraulic station, oil cylinder, piston, piston rod and the structure of the hydraulic station connected with the piston rod and the pressure plate. consists of: motor, oil pump, relief valve (regulating pressure) reversing valve, pressure gauge, oil circuit, oil tank. Hydraulic pressure mechanical compaction, the hydraulic station for the high pressure oil, oil cylinder and a piston component cavity filled with oil, when the pressure is greater than the pressure plate running friction resistance, pressure plate slow pressure filter plate, when the pressure force to achieve the relief valve set pressure value (by pressure gauge pointer display), filter plate, filter box (plate and frame type) or filter plate (van) is compact and started unloading overflow valve,At this time, cut off the motor power supply, the compression action is completed, back, reversing valve reversing, pressure oil into the rod chamber of the cylinder, when the oil pressure can overcome the friction resistance of the compression plate, the compression plate began to return.Automatic pressure for hydraulic pressure, clamp force is controlled by the electric contact pressure gauge, the gauge of the pointer and UCLA’s pointer to set the value of process requirement, when the pressure force reaches pressure gauge highs, power cut, the oil pump to stop the power supply, oil system due to the possible leakage and leakage cause the loss of compression force, when the lower limit to the pressure gauge pointer, power on,The oil pump starts to supply oil, and when the pressure reaches the upper limit, the power supply is cut off and the oil pump stops supplying oil, so that the circulation can ensure the effect of compression force in the process of filtering materials.

Filter mechanism:

the filter mechanism is composed of filter plate, filter frame, filter cloth and pressing diaphragm. The two sides of the filter plate are covered by the filter cloth. When the pressing diaphragm needs to be configured, a group of filter plates is composed of diaphragm plate and side plate.The base plate of the diaphragm plate is covered with rubber diaphragm on both sides, and the diaphragm is covered with press cloth on the outside. The side plate is the ordinary filter plate.The material enters the filter chamber from the material hole on the thrust plate, and the solid particles are trapped in the filter chamber because their diameter is greater than the aperture of the filter medium (filter cloth), and the filtrate flows out of the liquid hole under the filter plate.When the filter cake needs to be pressed dry, in addition to pressing by diaphragm, compressed air or steam can be used to pass through the washing port, and the air flow flusher the water in the filter cake to reduce the moisture content of the filter cake.

Filtering way

Filtrate outflow way clear flow filtration and undercurrent filtration.
1, open flow filtration: each filter plate under the liquid hole is provided with a water nozzle, filtrate directly out of the nozzle.
2, undercurrent filtration: under each filter plate is provided with a liquid outlet hole, a number of filter plate liquid outlet hole connected into a liquid outlet
The channel is discharged from the pipe connected with the outlet hole under the thrust plate.

washing method

When filter cake needs washing, there are open-current one-way washing and two-way washing, undercurrent one-way washing and two-way washing.
1. Open-flow one-way washing is that the liquid enters from the liquid inlet hole of the thrust plate in turn, passes through the filter cloth and then passes through the filter cake, and flows out from the non-porous filter plate. At this time, the liquid outlet nozzle of the perforated plate is closed, and the liquid outlet nozzle of the non-perforated plate is open.
2, open flow two-way washing is, wash liquid from the thrust plate above the two sides of the wash into the hole has been washed twice, that is, wash liquid first from one side to wash from the other side, wash liquid export and import is diagonal direction, so it is also called two-way cross washing.
3, the undercurrent one-way flow is, the wash liquid from the thrust plate wash into the hole into the hole plate, through the filter cloth and then through the filter cake, out of the non-porous filter plate.
4, undercurrent two-way washing is washing liquid from the top of the check plate on both sides of the two liquid into the hole has two washing, namely washing from one side first, and then washing from the other side, the outlet of the liquid is diagonal direction, so it is also called undercurrent two-way cross washing.

filter cloth

filter cloth is a kind of main filter medium, the selection of filter cloth and use, has a decisive effect to filtering effect, choose according to the filter material when PH value, such factors as the solid particle size to choose the appropriate filter cloth filter material and aperture to ensure low cost and high filtration efficiency, when using, to ensure that the filter cloth level not discounted, aperture open.

Filter press Classification:

1: plate and frame filter press is composed of alternately arranged filter plate and filter frame a group of filter chamber.The surface of the filter plate is grooved and its projecting part is used to support the filter cloth.The filter frame and the filter plate have a through hole on the corner, after assembly to form a complete channel, can pass into suspension, washing water and filtrate.Both sides of the plate and frame are provided with handles to support the beam, and the plate and frame are pressed by the pressing device.Press cloth between plate and frame acts as sealing gasket.The feed pump will suspend hydraulic pressure into the filter chamber and form filter residue on the filter cloth until it fills the filter chamber.Filtrate through the filter cloth and along the filter plate groove flow to the plate frame corner channel, centralized discharge.After filtration, clean water can be used to wash the filter residue.After washing, sometimes also through compressed air, remove the remaining washing liquid.Then open the filter press to remove the filter residue, clean the filter cloth, re-press the plate and frame, and start the next working cycle.

2. The structure and working principle of the box filter press is similar to that of the plate and frame filter press. The difference is that both sides of the filter plate are concave, and each two filter plates are combined into a box filter chamber, leaving out the filter frame.This filter is suitable for suspensions which need to be filtered at higher pressure and the filter residue does not need to be washed.

3. Vertical filter press filter plate is stacked horizontally and up and down, forming a group of filter chamber, covering a small area.It adopts a continuous filter belt. After filtration, it moves the filter belt to discharge slag and clean the filter belt. The operation is automatic.The filter press has a wide range of application and simple structure.The pressing and opening of plate and frame, slag discharge and cleaning of press cloth can be carried out automatically, which is conducive to the development of large-scale filter press.After the elastic rubber diaphragm is added to the filter chamber of the filter press, the filter residue can be compressed by the rubber diaphragm at the end of the filtration with high pressure water or compressed air, so that the filter residue is further pressed and dehydrated, forming the filter chamber volume variable, the filter residue is compressed and the pressure can reach 1~2 mpa.

4. Belt filter press is widely used in municipal sewage treatment, chemical industry, oil refining, metallurgy, paper making, leather, food, coal washing, printing and dyeing and other industries of sludge dewatering, the machine continuous operation, high degree of automation, energy saving, efficient, easy to use and maintenance, is the ideal equipment for sludge dewatering.

Dehydration application:

1: Filter press as a mature dehydration equipment, is widely used in the field of environmental protection, become an important equipment for sewage sludge treatment.
2: sludge mechanical dehydration is mainly to remove the capillary water between sludge particles, sludge moisture content after dehydration of ordinary machinery is often 65%-80%, in the shape of mud cake.
3: mechanical dehydration equipment in the past mainly belt filter press, plate frame filter press and horizontal screw sedimentation centrifuge, now commonly used chamber filter press, vertical hydraulic filter press, membrane and high pressure plate frame machine.
4:When using sludge landfill, sludge dewatering can greatly reduce the accumulation site of sludge, save the cost in the process of transportation;In the process of sludge composting, sludge dewatering can ensure the smooth composting (generally speaking, sludge has a low moisture content in the composting process);If the sludge incineration, centralized treatment, high sludge dehydration rate can greatly reduce the heat consumption, reduce the cost of treatment of harmful substances.
5: However, the sludge composition is complex, relatively small density, fine particles, and often colloidal state, determines the characteristics of its not easy to dehydrate, so far.In addition to the ultra-high pressure vertical hydraulic filter press, the rest of the filter press are increased drying process to reduce residual oil (liquid) rate.
6: low consumption of belt filter press.The cake moisture content of plastic plate and frame filter press is low, but the horizontal screw sedimentation centrifuge has strong adaptability to sludge flow fluctuation, good airtight performance, large processing capacity and small footprint.In the past, most sewage treatment plants in China use centrifuges, belt filter press and plate and frame filter press, and small sewage treatment plants generally use concentrated dehydration integrated machine.Now commonly used box filter press, diaphragm filter press, and ultra-high pressure vertical hydraulic filter press, its unique technology, is the ideal equipment for sludge dewatering.

Belt filter press:
1: continuous work, belt press dehydrator has three working areas, namely gravity dehydration area, wedge press dehydration area and shear press dehydration area, the press type belongs to two-dimensional press, mainly used for sludge dewatering, but its application scope is expanding.The dewatering effect of belt filter press is more dependent on chemical agents, resulting in high cost of sludge treatment.

Plate and frame filter press:
1: intermittent pressure filtration equipment, used for solid-liquid separation of various suspensions.
2 box filter press: it is developed after the 1960s.Its characteristics are high filtration pressure, the highest pressure has reached 4.5mpa;The single-machine filter area is large, the foreign products of 2050 square meters have been published, the domestic maximum filter area has reached 2000 square meters, the filter cake liquid content is low, the press filter cake moisture content can be reduced by 5% to 15%;Good corrosion resistance, filter plate can use a variety of enhanced plastic, light weight, good elasticity, corrosion resistance, wide adaptability;Low operating cost, can realize multiple continuous operation, online control.Modern filter press is mainly based on the wing type.

membrane filter press:
1: intermittent pressure filtration equipment, used for solid-liquid separation of various suspensions.The filter press is equipped with a rubber press diaphragm to dehydrate the cake.The medium that causes the diaphragm to expand can be compressed air (used below 0.7MPa) or water (used above 0.7MPa).
2: ultra-high pressure vertical hydraulic filter press: unique filter chamber structure, the sludge is pressed twice, the sludge moisture content after the press is less than or equal to 50%;Press edible oil residual oil rate is low, leading technology in China, is currently the preferred application of many manufacturers.

Sludge conditioning:
General life mechanical dewatering of sludge with higher molecular weight polymer, common through “conditioning” processing, there are different ways to conditioning, a thermal physical method, such as “hot water”, “water heat drying”, “to wet oxidation” and so on, there are physical method, such as ultrasonic, microwave, etc., is one of the most chemical method, by adding some inorganic chemical salts (agents),It can change molecular charge polarity of sludge, increase particle porosity, improve pressure filtration characteristics and other effects. At present, the most common and cheapest technology on the market is the combination of “sludge chemical conditioning + filter press treatment”.

Installation and debugging:

1. The filter press should be installed on the flat concrete foundation. Feed end thrust plate machine foot with foot bolt fixed on the foundation; Bracket end without anchor bolts, or anchor bolts after positioning with two nuts locked, nut gasket and machine foot leave appropriate gap, the machine foot can be micro expansion. Before positioning, the installation personnel should correct the perpendicularity of the beam and the thrust plate.
2. The foundation structure should be designed by construction engineers according to the load of the equipment. It is advisable to reserve two grouting holes for anchor bolts.
3. There should be enough operation and maintenance space around the filter press. The hydraulic pressure filter press should choose an appropriate position to place the hydraulic station to ensure that the hydraulic station can work normally.
4, according to the requirements of the work, put the filter plate, layout of feeding, washing and drainage pipeline. Equipped with filter pressure indicator and reflux channel to control filter pressure. For diaphragm extruded type, the compressed air line is arranged.
5, hydraulic filter press, hydraulic station tank into clean 20#-40# hydraulic mechanical oil, the use of temperature >-5℃;If the ambient temperature is low, hydraulic oil with similar viscosity and low freezing point can be selected. Hydraulic oil must be added through 80-100 mesh filter.
6, mechanical or hydraulic pressure device, power on the starting motor should work correctly. The pressure gauge should rise steadily when the hydraulic pressure is pressed and there is no discharge phenomenon in the hydraulic system. The working pressure of the hydraulic station should be adjusted correctly according to the size of the model. If the oil tank is found to be insufficient after the test, it should be supplemented.

Maintenance matters:

1, normal adjustment of the filter press before feeding work, each shift before the overall inspection of the machine.Mechanical pressing transmission parts and reduction box must add enough lubricating oil;Hydraulic pressure recheck the oil storage amount of the oil tank and the working pressure of the hydraulic station. The hydraulic oil is generally replaced once a year. When the hydraulic system is replaced, it should be comprehensively cleaned.
2. It is forbidden to start work in the factory when the number of filter plates is less than the specified number, so as not to damage the parts.Before feeding, check the arrangement of the filter plate. The press cloth should not be folded to prevent large leakage.After unloading cake, the filter plate must be pressed tightly and arranged neatly.
3, until everything is normal before pressing the filter plate pressure filtration, filtration pressure and filtration temperature must be within the specified range, too high filtration pressure will cause leakage, filtration temperature is too high plastic filter plate deformation, feeding suspension to uniform concentration.There shall be no mixture;After cake unloading, the filter cloth and the filter plate must be washed clean, and the residue is not allowed to stick in the sealing surface or feed channel, otherwise it will affect the flow of feed and the sealing of the filter plate, resulting in the pressure imbalance on both sides of the filter plate, resulting in deformation and damage of the filter plate.
4, the choice of filter cloth must conform to the requirements of the propeller of filtration technology, should be shrunk before new filter cloth production, the hole diameter should be less than the filter plate aperture, the matching filter plate holes and hole of the plate should be relatively concentric, Jane should feed opening cloth tiejin compared. in addition, otherwise it will cause, filter, filter rate is low, cloth tube rupture, short of filtering the expected goal.
5. In the early stage of the filter press, the filter is cloudy. When a layer of filter cake is formed on the filter cloth, the filtrate will become clear.If the filtrate is always cloudy or clear and mixed, the press cloth may be damaged or the holes in the cloth may deviate from the holes in the plate. In this case, close the valve or stop feeding to replace the press cloth. A small amount of leakage caused by filter cloth capillarity is allowed between the filter plates.
6, when moving the filter plate, the force should be uniform and appropriate, no collision, wrestling, so as not to damage the sealing surface and the filter wrench handle. The press cloth will harden after being used for a period of time and its performance will deteriorate, so it needs to be checked regularly. If any change is found affecting the filtration rate, the press cloth can be neutralized and cleaned with the corresponding weak acid and weak base at a low concentration to restore its function. If it cannot recover, the press cloth can be replaced in time.
7, slurry, lotion or compressed air valve, must be started according to the operating procedure, can not be started at the same time, the compressed air pressure can not exceed the filtration pressure when the diaphragm is squeezed.

Filter Press Applications

Filter presses can be built in a wide range of sizes, from small, lab-scale 150 mm presses, to those with much larger capacities, such as those with 1500 and 2000 mm filter plates. Filter presses are used for liquid/solid separation in an extensive range of industries and applications including:

Food and beverage processing
Chemical manufacturing
Mining
Power generation
Aggregates, asphalt and cement production
Steel mills
Municipal plants
And more…
Customizing A Filter Press for Your Application Needs
The industry, application and operational considerations will guide specifics such as the overall design, filtration capacity, number of chambers, filter plate size, materials of construction, as well as additional features/systems such as automatic plate shifters, cloth washing system, drip trays, cake shields and safety light curtains. Design of a filter press depends on a host of factors such as filtration cycle time, cake dryness required, cloth life, whether manual or automated plate shifting is desired, and many other factors.

Contact the Experts at Jingjin
If you’re interested in learning more about how a filter press could be customized for your specific application, Contact Jingjin Equipment Inc. today. Or we may have just the right standard or used filter press in-stock to meet your needs today. Contact Jingjin Equipment Inc. today and benefit from our engineered filtration experience.

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