Plate and frame filter presses are mechanical devices used to separate solids from liquids by passing the feed slurry between plates with filter cloths. They consist of multiple filter plates assembled together in a stacked arrangement within a frame. When the feed material is pumped into the system, the solid particles are trapped on the filter cloths while the liquid drains out.
Plate and frame presses are employed across industries for dewatering sludges, concentrating suspensions and separating liquids of varying viscosities. In this article, we will discuss how they work, common types, factors to consider when buying and typical applications.
How Do Plate and Frame Filter Presses Work?
A plate and frame filter press consists of alternate plates containing filter cloths and spacing plates that maintain a gap between the filter plates. The plates are assembled together within a frame with hydraulic pistons on each side.
When the pistons exert pressure on the frame, the plates are pressed together forming wedge shaped filter chambers in between. The resulting high surface area to volume ratio within the chambers allows for efficient filtration.
The feed slurry is then pumped into these chambers. The solid particles in the slurry are trapped on the filter cloth while the liquid passes through and collects in channels in the spacing plates.
As more and more solids are deposited, a filter cake forms on the filter cloth.Meanwhile, the hydraulic pistons continue applying pressure to squeeze out liquid from the cake.
Eventually, the feed supply is shut off and the plates are separated, exposing a dry filter cake that needs to be discarded. Fresh filter cloths are then installed for the next cycle.
Types Of Plate And Frame Filter Presses
There are two main types based on mode of operation:
- Continuous: The plates remain stationary while feed material is continuously fed into chambers. Used when a constant supply of feed slurry is available.
- Batch: The plates move to expose fresh filter areas periodically. Used for intermittent filtration where the feed material must be stored first.
Factors To Consider When Buying Plate Frame Type Filter
When shopping for plate and frame filter presses, consider:
- Feed Material: Particle size, viscosity, acid/base levels and other properties.
- Plate Size: Determines throughput capacity. Larger plates filter more volume per hour.
- Plate Material: Stainless steel or other alloy suitable for your chemical process.
- Operating Pressure: Higher pressures yield drier filter cakes but require sturdier construction.
- Temperature Range: Ability to handle hot or cold feeds.
- Frame Design: Size, stiffness and number of pistons based on required operating pressures.
- Automation: Options like PLC controls, load cells for pressure monitoring.
- Spare Parts: Availability of filter cloths, gaskets and seals for replacement.
- Manufacturing Certifications: Meet standards for your industry.
- Warranty and After-Sales Support: Indicators of manufacturer reputation and product quality.
Filter Presses With Related Common Applications
Plate and frame filter presses find extensive use across different industries for:
- Mineral Processing: Dewatering mineral slurries from mining operations.
- Chemical Production: Concentrating and recovering valuable chemicals from byproduct streams.
- Wastewater Treatment: Separating primary and secondary sludges from municipal and plant effluents.
- Food Processing: Removing moisture from mash and pulp in brewing, juice and dairy plants.
- Pharmaceuticals: Isolating precipitates, crystalline materials and other products.