The working principle of a filter press revolves around the creation of sealed filter chambers to separate solids from liquids. By pressing filter plates and frames together, the system ensures effective filtration, producing dry filter cakes and clear filtrates. This technology plays a crucial role in resource recovery and pollution control across various industries. In this post, Yuwei Filtration will discuss filter press working principle.
A filter press is an industrial equipment that realizes solid-liquid separation by means of mechanical pressure. Its core is to form a sealed filter chamber through the combination of filter plates, filter frames, filter cloths and other components, and use the pressure difference to promote the separation of liquid and solid in the suspension.
In terms of structure, a filter press is mainly composed of filter plates, filter frames, filter cloths, and a pressing device. The surface of the filter plate is provided with liquid guide grooves, the filter cloth covers the filter plate to act as a filter medium, the filter frame serves as a space for accommodating filter cakes, and the pressing device presses the plates and frames through hydraulic or manual means to ensure the tightness of the filter chamber.
With its efficient separation capacity, filter presses are widely used in chemical industry, mining, environmental protection, food, pharmaceutical and other fields. They can dehydrate high-solid-content slurries, reduce the moisture content of filter cakes, and recover valuable filtrates, playing an important role in resource utilization and pollution control. Common types include plate and frame filter presses, chamber filter presses, and membrane filter presses. Different types have slight differences in structure and applicable scenarios, but their core functions are based on the principle of solid-liquid separation.
Due to the iterative upgrading of structural design and precise adaptation to functional scenarios, filter presses are mainly divided into three types: plate and frame filter presses, chamber filter presses, and membrane filter presses, each with different working principles.
Structure: Composed of alternately arranged filter plates and filter frames.
The alternately arranged filter plates and filter frames are tightly pressed together by the pressing device, so that independent sealed filter chambers are formed between adjacent filter plates and filter frames, and filter cloths are clamped between the filter plates and filter frames.
The suspension to be filtered is pumped in from the feeding port in the center of the filter frame, diffuses around the filter frame under pressure. The liquid component passes through the filter cloth, collects through the liquid guide grooves on the surface of the filter plate, and is discharged from the filtrate outlet to become the filtrate.
Solid particles are intercepted by the filter cloth and gradually accumulate in the filter frame until they fill the entire space of the filter frame.
When the filter cake fills the filter frame or the set filtering time is reached, the pressing device is released, the filter plates and filter frames are separated, and the filter frame can be taken out to obtain the filter cake.
Structure: Adopts an integrated filter plate (without a separate filter frame). The concave cavities on both sides of the filter plate form the filter chamber, and the edge of the filter plate is provided with a feeding port and a liquid outlet.
The pressing device presses multiple integrated filter plates together, so that the double-sided concave cavities of adjacent filter plates form a number of sealed filter chambers. The surface of the filter plate is covered with filter cloth, and the feeding port and liquid outlet on the edge are connected.
The suspension enters each filter chamber through the feeding port on the edge of the filter plate, and fills the space of the filter chamber under pressure.
The liquid component passes through the filter cloth and is discharged from the liquid outlet through the liquid guide grooves on the surface of the filter plate; solid particles are intercepted by the filter cloth and gradually form filter cakes in the filter chamber.
After filtering, the pressing device is released to separate the filter plates, and the filter cake falls off from the concave cavity of the filter plate by its own gravity or mechanical vibration.
Structure: On the basis of the chamber filter press, elastic diaphragms are installed on one or both sides of the filter plate.
Same as the chamber filter press. The pressing device presses the filter plates with elastic diaphragms to form a sealed filter chamber. After the suspension enters the filter chamber, the liquid is discharged through the filter cloth, and solid particles form an initial filter cake.
When the filter cake reaches a certain thickness, high-pressure water or compressed air is injected into the pressure chamber between the diaphragm and the filter plate through an independent liquid/air inlet, so that the diaphragm expands and squeezes the filter cake, further squeezing out the residual liquid in the filter cake.
After secondary pressing, the moisture content of the filter cake is reduced to meet the requirements of deep dehydration.
The filter plates are released, the filter cake falls off, and the equipment is reset to prepare for the next filtering cycle.
