Plate and Frame Filter Press

The design of the plate and frame filter press uses a flat solid plate covered with a filter press cloth with a hollow frame between each plate. A metal skeleton holds and clamps the filter plates together to form a chamber, which is formed by flushing plates on either side of the frame, and the output filter cake is collected inside the frame. Advantages include low cost, high strength and easy internal inspection.

How does a plate and frame filter press work?

Slurry is pumped into the corner holes and flows into each frame, allowing solids to accumulate on the filter cloth. The remaining filter liquid (also called filtrate) then moves to the drain in the flushing plate and into the corner holes that are not used for the feed slurry. The filtrate then flows to the discharge pipe and is directed to the next step in the process.

After a period of time, the frames are filled with solids, the slurry feed pump is turned off and the filter press is ready to open. Each frame should now contain a filter cake, which is the end result of the solids forming on the filter cloth. The filter cake is then scraped out of the frames using a scraper and ideally falls into a filter cake funnel located below the press.

Advantages

Plate and frame filter presses allow for quick filter cloth changes, as well as the ability to use a wider range of filter media materials, including paper, which is typically used for fine filtration applications.

In processes where immediate particle retention is important, filter paper may be required because fine solids can block the filter cloth or simply pass through it. The filter cloth can be reused, but replace the filter paper after each filtration cycle.

Plate and frame presses are best suited for projects where filtration area is more important than volume. This is why plates and frames are most prominent in polishing applications (as opposed to dewatering projects) where the feed solids concentration is typically well below 1% (by weight).

Size the polishing application for a specific filtration area based on the process flow rate and a known flux rate (volume per unit time per area). To avoid the drop in filtration flow rate that can be achieved when the press is filled with solids, polishing applications often include redundant filter presses that are also sized to accept 100% of the required process flow rate.

Disadvantages

One of the disadvantages of the plate and frame design is the possibility of establishing uneven pressure between the frames, which can lead to plate damage. This problem stems from the fact that the frames are fed through a small opening in the corner, which can lead to clogging. This blockage can cause one frame to become full, while the next frame remains empty online.

Another disadvantage is the potential for leakage. The filter plates used in plate and frame presses are gasketless, which allows them to draw off liquid under pressure. This type of filter press is usually mounted on a raised platform or placed on a pit where any leaking liquid can be more easily collected.

FAQ

Plate and frame filter is widely used in pharmaceutical, biochemical, food and beverage, water treatment, brewing, petroleum, electronic chemical, electroplating, printing and dyeing, environmental protection and other industries, and is the latest equipment for filtration, clarification and purification of various liquids.

The plate frame is the core of the plate frame filter press. The quantity, quality and material of the plate frame have a great impact on the plate frame filter press. The material is the core of the plate frame filter press. The material of the plate and frame filter press is mainly composed of the following four kinds:

Rubber filter plate and filter frame

Rubber is a good acid and alkali resistant material, but its utility is limited by temperature, generally not more than 75℃, and there is aging phenomenon.

Plastic filter plate

The plastic filter plate used by the plate and frame filter press is an improved polypropylene plastic filter plate, in which filler, toughening agent, anti-aging agent, antioxidant and other auxiliary materials are added, so that it has very good advantages.

Glass filter plate

The glass filter plate is the glass steel form of the adhesive material of synthetic resin, and the glass fiber is used to increase its strength. Such a filter plate has the following advantages: light weight and high strength; Acid, alkali, salt and other media corrosion, long service time; The temperature of filtrate can be about 100℃, good heat resistance. And its disadvantage is the same as plastic, to age, but more slowly than plastic.

Filter plate of wood filter press

Wood filter board is generally used in the shirt wood quality, such wood filter board has good sealing, not easy to leak. The manufacturing process is more convenient, compared with the worries of other materials, the weight is also lighter, convenient transportation and movement. The disadvantage is that the strength of the wood itself is not high, so the filter plate is easy to damage, use period, easy to be corroded.

Yes, plate and frame filter presses are commonly used for batch filtration.

The structure of plate and frame filter press is composed of three parts.

First, Frame: the frame is the foundation part of the plate and frame, the two ends are the stopping plate and the pressing head, the beams on both sides connect the two, the beams are used to support the filter plate, the filter frame and the pressing plate.

a, thrust plate: it is connected with the support to situate one end of the plate frame on the foundation, the middle of the box type thrust plate is the feed hole, four corners and four holes, the upper two corners of the hole is the washing liquid or press gas import, the lower two corners for the export of dark flow structure or filtrate export

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 of environmental corrosion, can choose hard polyhydroethylene, polypropylene, stainless steel cladding or new anti-corrosion coating and other coatings.

Second, the compression mechanism: manual compression, mechanical compression, hydraulic compression.

a. Manual pressing: the screw type mechanical jack pushes the pressing plate to press the filter plate.

b. Mechanical pressing: The pressing mechanism consists of motor with advanced overload protector reducer, gear payment, screw and 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, and when it reaches the current value set by the protector, it reaches the big pressing force, the motor cuts off the power 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 and stops when the pressure block on the pressing plate touches the travel switch.

Three, the filtering mechanism

Plate and frame filter press filter mechanism consists of filter plate, filter frame, filter cloth and press diaphragm. Both sides of the filter plate are covered by filter cloth, and when the press diaphragm needs to be configured, a group of filter plate consists of diaphragm plate and side plate. The substrate of the diaphragm plate is covered with rubber diaphragm on both sides, and the outer edge of the diaphragm is covered with filter cloth, and the side plate is the common filter plate. The solid particles are intercepted in the chamber because their particle size is larger than the pore size of the filter media (filter cloth), 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 to pass through the washing port, and the airflow flushes away the water in the filter cake to reduce the water content of the filter cake.