Activated Carbon Filter Manufacturer: What are the main classifications of activated carbon filters?

What are the main classifications of activated carbon filters?

Filters are classified into three types—gravity filters, vacuum filters, and pressure filters—based on the method used to generate the filtration driving force.

Gravity

The gravitational force and hydrostatic head of the suspension generate pressure across the filtration medium, serving as the driving force for filtration; this process is typically carried out as an intermittent operation, such as sandpaper filtration.

Vacuum

An activated carbon filter generates negative pressure at the filtrate outlet, serving as the driving force for filtration. The absolute operating vacuum in industrial vacuum filters typically ranges from (2.5 to 8.0) × 10⁵ Pa. During filtration, the temperature of the suspension should be kept below the vaporization temperature of the filtrate under the prevailing vacuum conditions. Vacuum filters are classified into two types: batch operation and continuous operation. Batch vacuum filters can handle suspensions of varying concentrations. In such a filter, the vessel shell is filled with the suspension, and filter leaves equipped with wipers on both sides are immersed in the suspension; the filtration chamber is connected to a vacuum system. After the filtrate is drawn off, it is discharged through a conduit, while the cake accumulated on the surface of the filter leaves is removed after the equipment is shut down. Continuous vacuum filters are suitable for processing thick suspensions containing large amounts of solid particles. Drum vacuum filters, internal-filter drum vacuum filters, disc vacuum filters, and tumble vacuum filters all operate on similar principles.

The activated carbon filter divides the entire filtration surface into multiple independent filtration chambers. Each rotating chamber is sequentially connected to fixed pipelines via valve distribution, allowing for the intake of filtrate, wash liquor, or compressed air. As each chamber completes a full rotation, the entire filtration process is carried out; the coordinated operation of multiple chambers ensures continuous filtration. The belt vacuum filter has a structure similar to that of a belt conveyor and features a continuous filtration belt well suited for easily filterable suspensions. Both belt vacuum filters, internal-filter drum vacuum filters, and tumble vacuum filters operate with the filtration medium (filter cloth) positioned on top, making them particularly suitable for suspensions with high solid particle density and rapid settling.

Pressurize

Activated carbon filters utilize either pressure applied to the slurry inlet or mechanical squeezing pressure exerted on the wet filter cake as the driving force for filtration, making them suitable for handling slurries with high differential pressures. They are classified into batch and continuous operations. Batch-operated heat-tube pressure filters and pressure filters are typically used for filtering low-concentration slurries. Filter presses, also operating in batch mode, come in three types—plate, chamber, and vertical—and find extremely wide applications. Oil filters are plate-type filter presses equipped with auxiliary components such as oil pumps and vacuum evaporators. Continuous-operation drum pressure filters and disc pressure filters perform pressure filtration within sealed housings; their structures are similar to those of rotary vacuum filters and disc vacuum filters. However, due to their complex construction, these latter types are less commonly used.

Common pressure filters are characterized by a small filter chamber volume or by the application of mechanical squeezing pressure during filtration, making them suitable for suspensions with low moisture content and high solid particle concentrations. In belt press filters, the wet cake, which has undergone preliminary dewatering by gravity or vacuum, moves between two filter belts and is then further dewatered through roller pressing. Spiral press filters consist of a perforated cylindrical drum containing a rotating screw; the screw grooves vary in depth, causing the material to be conveyed from the deep-groove end to the shallow-groove end, thereby gradually reducing the cross-sectional area of the filtration chamber and subjecting the material to progressive compression. The filtered liquid is discharged through the holes in the cylinder, while the solid cake is expelled from the small-end opening.