Belt type Filter Press

1. Working Principle: The Synergistic Effect of Gravity and Pressing

The operation of a belt filter press can be clearly divided into three core stages, simulating the dewatering logic of "draining first, then squeezing":

1. Gravity Drainage Zone: The chemically conditioned (flocculated) sludge is first evenly distributed on the upper filter belt. In this section, a significant amount of free water drains through the belt by gravity, reducing the sludge's mobility and preparing it for subsequent pressing.

2. Wedge-shaped Pre-pressure Zone: The filter belt slowly enters a gradually narrowing wedge-shaped space. Gentle squeezing further concentrates the sludge, ensuring it is evenly and stably distributed on the belt and releasing more water, laying a solid foundation for high-pressure dewatering.

3. High-Pressure Dewatering Zone: This is the key stage. The sludge is sandwiched between the upper and lower filter belts and passes through a series of rollers with decreasing diameters. The arrangement of these rollers creates significant surface pressure and strong shear forces, effectively squeezing out the capillary water between sludge particles, ultimately forming a dry and solid cake.

2. Core Product Characteristics (Advantages)

1. Highly Efficient Continuous Operation, Large Processing Capacity: This is the most prominent advantage. Unlike chamber filter presses that operate in batch cycles (feeding-pressing-cake discharge), it can run uninterrupted 24/7. Sludge enters from one end, and dry cake is continuously discharged from the other, making it particularly suitable for large-flow, continuous production scenarios like large municipal wastewater treatment plants.

2. High Dewatering Efficiency, Controllable Cake Moisture Content: The multi-stage process (gravity, low-pressure, high-pressure) ensures significant dewatering effectiveness. For municipal sludge, it can typically reduce moisture content from over 98% down to between 75% and 85% in one step. The cake dryness can be controlled within a range by adjusting belt speed, pressure, and flocculation.

3. High Degree of Automation, Low Labor Costs: Modern belt filter presses are generally equipped with PLC automatic control systems, enabling one-button start/stop, automatic belt tension adjustment, real-time monitoring, and alarm reporting. The entire process requires minimal manual intervention, significantly reducing labor intensity and technical dependency.

4. Relatively Low Investment and Operating Costs:

 ◦ Low Energy Consumption: Main power consumption comes from motors driving the belts and the cleaning water pump. Energy consumption is usually lower compared to diaphragm filter presses of similar capacity.

 ◦ No Filter Cloths Required: It uses high-strength polyester filter belts. Although these require regular cleaning/replacement, managing their maintenance and spare parts cost is simpler compared to the large number of cloths needed for chamber presses.

5. Simple Structure, Easy Maintenance: The device is relatively open-structured. Key components like the filter belts, rollers, and spray nozzles are easy to observe and access. Routine maintenance (e.g., cleaning nozzles, adjusting tracking) is straightforward. Periodic belt replacement is also relatively convenient, reducing downtime.

3. Suitable Materials and Application Scenarios

Belt filter presses are not universal; their performance is highly dependent on feed material characteristics. They are particularly suitable for:

• Municipal Sludge: The classic application for organic sludge from domestic and industrial wastewater treatment.

• Inorganic Fine-Particle Sludge: Such as coal slime from washing plants, tailings from mineral processing, and metallurgical sludge.

• High-Concentration, Free-Flowing Materials: The material must be well flocculated to form strong flocs that can withstand pressing without extruding through the belt.

4. Limitations (Characteristics to Note During Use)

1. Sensitive to Feed Characteristics: The concentration, particle size, pH, and especially the flocculation effectiveness directly impact dewatering performance. Poor flocculation can cause sludge to spill from the sides of the belt ("sludge run-off").

2. Not Suitable for Highly Viscous Materials: Excessively sticky materials tend to adhere to the belt, making cleaning difficult and affecting operation.

3. Potentially Wet Working Environment: As an open dewatering device, operation can create a misty environment, which is less clean compared to fully enclosed equipment.

4. Requires Continuous Belt Washing: A high-pressure cleaning system is essential to maintain filtration efficiency, consuming water and energy.