The belt press filter mainly consists of a drive device, frame, pressing rollers, upper filter belt, lower filter belt, filter belt tensioning device, filter belt cleaning device, discharge device, pneumatic control system, and electrical control system.

Working Principle and Dewatering Process

After the concentrated sludge is thoroughly mixed with a specified concentration of flocculant in static and dynamic mixers, the fine solid particles in the sludge aggregate into larger flocculated masses, simultaneously separating free water. The flocculated sludge is then conveyed to the filter belt for gravity dewatering. Under the force of gravity, free water is separated, forming non-flowing sludge. This sludge is then sandwiched between the upper and lower filter belts and subjected to gradually increasing squeezing and shearing forces through the wedge-shaped pre-pressure zone, low-pressure zone, and high-pressure zone, progressively compressing the sludge to achieve the desired degree of solid-liquid separation, ultimately forming a filter cake for discharge.

1. Chemical Pretreatment Dewatering

To improve the dewaterability of sludge, enhance the properties of the filter cake, and increase material permeability, chemical treatment of the sludge is necessary. This machine uses an "in-water flocculation granulation mixer" to achieve chemical dosing and flocculation. This method not only provides excellent flocculation effects but also saves a significant amount of chemicals, resulting in low operating costs and significant economic benefits.

2. Gravity Concentration Dewatering Section

The sludge is evenly fed onto the filter belt through a distribution hopper. As the filter belt moves forward, free water flows into the water collection tank under its own weight. Gravity dewatering can also be considered a high-concentration section, primarily aimed at removing free water from the sludge, reducing its fluidity, and preparing it for further compression.

3. Wedge Zone Pre-Pressure Dewatering Section

After gravity dewatering, the sludge largely loses its fluidity. As the filter belt advances, the gap between the upper and lower belts gradually narrows, and the material begins to experience slight pressure. The pressure increases progressively with the movement of the belt. The wedge zone serves to extend the gravity dewatering time, enhance the compression stability of the flocs, and prepare the material for entry into the pressure zone.

4. High-Pressure Dewatering Section with Squeezing Rollers

Upon exiting the wedge zone, the material enters the pressure zone, where it is subjected to compression. The pressure increases along the direction of the filter belt movement as the diameter of the squeezing rollers decreases. The material volume contracts under compression, squeezing out the interstitial free water. At this stage, the filter cake is essentially formed. Continuing forward to the high-pressure section at the end of the pressure zone, the moisture content of the filter cake can be reduced to a minimum after high-pressure treatment.

5. Material Discharge

After undergoing the above dewatering stages, the material forms a filter cake and is discharged. It is scraped off by a mud scraper, and the upper and lower filter belts separate. Any residual material between the filter mesh pores is cleaned by high-pressure washing water, and the process continues into the next dewatering cycle.