The filter press uses a special filter medium to apply a certain pressure to the object to make the liquid dialysis out of a mechanical device. It is a commonly used solid-liquid separation device. It was used in chemical production at the beginning of the 18th century, and is still widely used in chemical, pharmaceutical, metallurgical, dye, food, brewing, ceramics and environmental protection industries.

The filter plate has stable performance, convenient operation, safety, and labor-saving; the metal press cylinder is processed by seamless steel pipe and precision-casted with plastic steel filter plate, which is resistant to high temperature, high pressure and durable.

 

How does a Filter Press Work?

The hydraulic pressure mechanism of the filter press is composed of a hydraulic station, an oil cylinder, a piston, a piston rod, and a Hafland card hydraulic station connected to the piston rod and the pressure plate. The structure consists of a motor, an oil pump, and an overflow valve (pressure adjustment). Directional valve, pressure gauge, oil circuit, oil tank.

Filtration method: the way the filtrate flows out is divided into open flow filtration and undercurrent filtration. For open flow filtration, a water nozzle is installed on the outlet hole under each filter plate, and the filtrate flows out from the water nozzle intuitively. Underflow filtration, a liquid outlet channel hole is arranged under each filter plate, and the liquid outlet holes of several filter plates are connected to form a liquid outlet channel, and the liquid outlet is discharged from the pipe connected with the liquid outlet hole under the thrust plate.

Washing method: When the filter cake needs to be washed, there are sometimes one-way washing and two-way washing, undercurrent one-way washing and two-way washing. 

 

The structure of the filter press consists of three parts:

frame

  • Thrust plate
  • Pressure plate
  • Girder

Hold-down mechanism

  • Manual compression
  • mechanical compression
  • hydraulic compression

Filter mechanism

The filter mechanism is composed of a filter plate, a filter frame, a filter cloth, and a squeeze diaphragm. The two sides of the filter plate are covered by filter cloth. When a squeeze diaphragm is required, a set of filter plates is composed of a diaphragm plate and a side plate. Both sides of the base plate of the diaphragm plate are covered with rubber diaphragms, and the outside of the diaphragm is covered with filter cloth. The side plates are ordinary filter plates. The material enters the filter chambers from the material holes on the thrust plate. The solid particles are trapped in the filter chambers because their particle size is larger than the pore size of the filter medium (filter cloth), and the filtrate flows out from the outlet holes under the filter plate. When the filter cake needs to be squeezed dry, in addition to squeezing with a diaphragm, compressed air or steam can also be used to pass in from the washing port, and the airflow can flush the water in the filter cake to reduce the moisture content of the filter cake.

Basically, the filter press design is based on the dewatering volume and type of slurry. JingJin is an expert in liquid and solid separation and offers a wide range of filter press types and capacities to suit specific application needs for trouble-free, economical dewatering. 

Dehydration application

  1. As a mature dewatering equipment, filter press is widely used in the field of environmental protection and has become an important equipment for sewage sludge treatment.
  2. The mechanical dewatering of sludge is mainly to remove the capillary water between the sludge particles. The moisture content of the sludge after ordinary mechanical dewatering is often 65%-80%, which is in the shape of a mud cake.
    In the past, mechanical dehydration equipment mainly included belt filter presses, plate and frame filter presses and decanter sedimentation centrifuges. Nowadays, chamber filter presses, vertical hydraulic filter presses, diaphragm machines and high-pressure plate and frame machines are commonly used.
  3. When using sludge landfill, sludge dewatering can greatly reduce the accumulation of sludge and save transportation costs; when composting sludge, sludge dewatering can ensure smooth composting (general requirements during composting Sludge has a lower moisture content); if sludge incineration and centralized treatment are carried out, the high sludge dehydration rate can greatly reduce heat energy consumption and reduce the cost of hazardous materials.
  4. The sludge composition is complex, the relative density is small, the particles are finer, and it is often in a colloidal state, which determines its non-dewatering characteristics. Therefore, except for the ultra-high pressure vertical hydraulic filter press, the other filter presses all increase the drying process In order to reduce the residual oil (liquid) rate.
  5. Belt filter press has low electrical consumption. The water content of the filter cake of the plastic plate and frame filter press is low, but the decanter sedimentation centrifuge has strong adaptability to sludge flow fluctuations, good airtight performance, large processing capacity, and small footprint. In the past, most sewage treatment plants in our country used centrifuges, belt filter presses and plate and frame filter presses, and small sewage treatment plants generally used concentration and dehydration integrated machines. Nowadays, chamber filter press, diaphragm filter press, and ultra-high pressure vertical hydraulic filter press are commonly used. They have unique technology and are ideal equipment for sludge dewatering.