Frame filter presses

Regarding their field of application, frame filter presses can be used for removing sludge from drinking water, dehydrating sewage sludge and reusing water used for cleaning in the oil and gas industries, as well as in agriculture, where they are used to press high moisture-content crops. Other fields of use include the ceramics, paint, chemical, pharmaceutical and food industries, metalworking and environmental protection. As regards size, both the dimensions and the numbers of the plates show a great deal of variability, these generally being unique to the specific task at hand. There are three types: chamber, frame and membrane filter presses.

Filter presses are highly efficient tools for separating solids and liquids since they are easy to install, use and maintain. They can be set for manual, semi-automatic or automatic operation.

The machine is made up of a series of filters consisting of polypropylene plates which are placed under pressure from two sides, moved by a hydraulic power unit. The frame system consists of alternating perforated and unperforated PP plates and press cloths. Press cloths are textiles woven from various types of elemental fibre (polyamide, polyester, PVC and others, which may be monofilament or multifilament fibres), selected according to the filtration conditions. These conditions include filter cake accumulation, efficiency, attrition, etc. Extreme pH values may sometimes be accompanied by extreme temperatures, which requires the use of filter textiles with various temperature ratings (PES, PA, PP, NX).

The plates allow liquids to pass through while the solids are retained by the filter cloths. The filter plates are concave and have chambers which trap the sludge or other substance to be removed as it is transported by the slurry pump. After all of the above mentioned chambers are filled, the filtrate drains off along the plates, or it is collected in the case of non-drip types. The series of filters is then opened up to allow the dehydrated filter cakes to drop into the container or slurry tank beneath it.

Filter presses use a modern “clean” technology that provides numerous advantages:

The costs of transporting and disposing of dried filtrate are less than those for liquid filtrate. They are also easier to handle and, if favourably classified, they may be used for agricultural purposes. Sludges with high organic matter content may also be used for biogas production. Companies that use filter presses are also able to reclaim the water used in the production process, which after suitable treatment can be reintroduced into the system. Non-drip construction guarantees environmentally friendly operation. The hydraulic system can withstand high loads and may be fitted with a compressed air pump to increase pressure. Together with increasing the size of the filter plates, this can exponentially increase the amount of material to be dehydrated.

Filter presses are easy to use and maintain. They can be used in various configurations, including in combination with suspension mixers, and they can also be equipped with self-cleaning systems.