Introduction
Intermittent filter presses are widely used in industrial processes, such as in industries such as mining, steel, pulp and paper, food and drink, pharmaceuticals, dyeing and printing and many other industries. An intermittent filter press consists of a series of plates with filter cloths between them. A slurry of liquefied material is pumped into the filter press, and the pressure within the filter press forces the liquid through the filter cloths, leaving a solid residue on the plates. The filter cloths are removed and the plates are reused, thus making the intermittent filter press a cost effective filtration option.
Working Principle
Intermittent filter presses use a litho-hydrocyclonic system which is based on the principle of centrifugal force. The force of the water causes the solid-liquid mix to divide, with the heavy liquid becoming the inner layer, and the lighter liquid becoming the outer layer. The inner layer is forced through the filter cloths, while the outer layer is fed back into the system, thus recycling the water.
Design
An intermittent filter press typically consists of two chambers, the filter media chamber and the return chamber. The filter media chamber contains the filters, while the return chamber contains the waste contaminated liquid. In portable filter press units, the filter media may be contained in a plastic cartridge, with the waste liquid being fed directly into a reservoir.
The filter media is supplied with the filter press and is selected based on the process and application. The filter media must be capable of allowing the desired particles to pass through the filter cloth and obstructing any larger particles from passing through. A common filter media is filter fabric, but other materials, such as activated carbon and stainless steel screens, may also be used.
Operation
An intermittent filter press is typically operated by a technician, who controls the pressure and flow rate of the incoming feed and adjusts the filters as needed during operation. The filter chamber is usually sealed, so that the slurry is trapped and the filter can be operated without interruption from outside particles.
The incoming slurry is pre-treated to ensure that the feed is free of any large particles which may block the filter cloths. The pre-treatment may either be mechanical or chemical, depending on the nature of the slurry. Once pre-treatment is completed, the filter press is primed with clean water, and the slurry is pumped into the filter chamber.
The pressure in the filter press is increased and maintained at a preset level, and the pressure forces the liquid through the filter media. The solid residue that is left behind on the filter plates is then manually removed and the filter plates are reused. After the filter plates have been cleaned and inspected, the filter press is then ready for the next batch of material.
Conclusion
Intermittent filter presses are an effective and economical method of filtration for many industrial applications. They are relatively easy to operate and maintain, and the filter plates can be reused multiple times. Intermittent filter presses are also a safer alternative to vacuum filters, as they do not require the use of flammable liquids or hazardous substances.
