What Is a Filter Presse?
A Filter Presse is a device for filtering slurry liquid and separating solid and liquid by pressing with a filter.
It is mainly used for water purification. It is characterized by its simple structure and the fact that it is relatively easy to increase the processing volume. Since it can be integrated into the production line, it is widely used as a filtration and dewatering device.
The resulting dewatered product (cake) has a very low moisture content and very high solid-liquid separation characteristics. Automatic Filter Presses are also available, which can be fully automated from liquid filling to filtration.
Uses of Filter Presses
Due to their high solid-liquid separation characteristics, Filter Presses are used in a variety of industries. Food processing and mining are examples of applications other than those listed below.
1. Environmental Applications
Typical applications are in the environmental field, where they are used for wastewater treatment and air pollution control. Wastewater treatment plants use Filter Presse to remove solids and produce purified water. The purified water is discharged into the sea or other bodies of water after confirming that it complies with discharge standards.
2. Chemical Industry
In the chemical industry, the filter press is used for purification, separation, and concentration of synthetic compounds. In organic synthesis, Filter Presse is sometimes used to separate reaction products from reaction by-products.
They may also be used in the refining process to remove impurities and improve product quality.
3. Petrochemical Industry
In the petrochemical industry, filter presses are used to manufacture petroleum products and chemicals. Specifically, it is used to remove impurities from oil in petroleum refining processes.
Principle of Filter Presses
Filter Presse consists of multiple filter chambers separated by two steel or plastic plates covered with filter cloth. A space is provided between the filter cloths, into which slurry is poured by a pump. After the slurry liquid has been poured into the filter chambers and filtration has progressed, further pressure is applied to dewater the material.
Hydraulic pressure is the most common method of applying pressure. After the hydraulic pressure is released, the filter chamber is opened, and the cake is dropped. In the case of a manual Filter Presse, hydraulic pressure is applied by a manual hydraulic pump.
The properties of the filter plates and filter cloth, which are the main components of the Filter Presse, are as follows:
1. Filter Plate
The filter plate is made of polypropylene or similar material. Its role is to fix and pressurize the filter cloth. The filter plate is made of a hard material that can withstand high pressure and has excellent chemical resistance.
Depending on the model of Filter Presse, it is possible to increase the filtration speed by feeding air between the filter plates to increase the pressure.
2. Filter Cloth
Cloth-like filter cloth made of polypropylene, nylon, polyester, or other materials. Various pore diameters are available, so the filter cloth can be used according to the solid content and particle size of the slurry. Currently, most Filter Presses are capable of automatically discharging solids by moving the filter cloth like a conveyor belt.
How to Select a Filter Presse
When selecting a Filter Presse, consider the properties of the slurry liquid, processing speed, and moisture content.
1. Properties of Slurry Liquid
The material of the filter plate and filter cloth should be determined according to the properties of the slurry liquid. If the slurry is corrosive, select stainless steel, etc. If the slurry is highly viscous, select a high-head compression pump, etc.
2. Throughput
Throughput is another important factor. It is one of the key indicators in determining the appropriate size of a Filter Presse and influences the design and construction of the Filter Presse. The larger the throughput, the larger the size.
3. Moisture Content
Based on the above, check the required moisture content. If you want to reduce the moisture content of the cake, you need to give sufficient time to remove excess water.
However, since this will reduce the processing volume, consider the equipment capacity according to the required processing volume and the required moisture content.
Other Information on Filter Presse
Filter Presse Leakage Prevention
Filter Presse may leak from the edges of the filter. Leakage can be caused by gaps, excessive pressure, or clogging of the filter cloth.
If there is a gap between the filter cloth and the frame, there is a possibility of leakage. In many cases, sealing the gap with a sealant will stop the leakage. Also, if the pressure is too high for the filtration speed of the filter cloth, there is a possibility that unprocessed slurry will leak.
The pressure should be lowered or the filter cloth pore size should be optimized. Leakage can also be caused by solids clogging the filter cloth and reducing filtration performance. Cleaning the filter cloth will improve the situation. Leakage also occurs when there are too many solids in the slurry, so the solids content must be reduced in the upstream process.