Desulfurization Gypsum Wastewater Treatment Equipment Belt Vacuum Filter

Manufacturer produces vacuum filters, Shandong Shuihui Environmental Engineering Co., Ltd. produces various types of vacuum filters. They are widely used in sludge dewatering, slurry dewatering, chemical residue dewatering, fruit residue dewatering treatment, and other fields.

Working Principle of Vacuum Filters

Vacuum filters operate by creating negative pressure at the filtrate outlet as the driving force for filtration. These filters are divided into two types: intermittent operation and continuous operation. Intermittent vacuum filters can handle suspensions of various concentrations, while continuous vacuum filters are suitable for filtering thick suspensions with a high content of solid particles.

Intermittent filters have developed due to their ability to achieve automated operation, with filtration areas becoming increasingly larger. To obtain filter residues with low moisture content, mechanically pressed filters have been developed.

By using a filter medium to separate the container into upper and lower chambers, a simple filter is formed. The suspension is added to the upper chamber, and under pressure, it passes through the filter medium into the lower chamber to become filtrate, while solid particles are retained on the surface of the filter medium to form filter residue (or filter cake).

During the filtration process, the accumulated layer of filter residue on the surface of the filter medium gradually thickens, increasing the resistance for liquid to pass through the filter residue layer and reducing the filtration rate. When the filter chamber is filled with residue or the filtration rate becomes too low, filtration is stopped, and the residue is cleaned to allow the filter medium to be reused, completing one filtration cycle.

For liquid to pass through the filter residue layer and the filter medium, resistance must be overcome, requiring a pressure difference on both sides of the filter medium, which serves as the driving force for filtration. Increasing the pressure difference can accelerate filtration, but particles that deform under pressure may clog the pores of the filter medium at high pressure differences, slowing down filtration instead.

Suspension filtration can occur in three ways: filter residue layer filtration, deep filtration, and screen filtration. Filter residue layer filtration refers to the formation of an initial residue layer after the initial filtration stage, after which the residue layer plays the primary role in filtration, retaining both large and small particles. Deep filtration involves a thick filter medium, with fewer solid particles in the suspension, and particles smaller than the pores of the filter medium; during filtration, particles enter and are adsorbed within the pores. Screen filtration retains solid particles larger than the pores of the filter medium, with no adsorption of solid particles inside the filter medium, such as in rotary screen filters that remove coarse impurities from wastewater.

In actual filtration processes, these three methods often occur simultaneously or sequentially. The processing capacity of a filter depends on the filtration rate. When solid particles in the suspension are large and uniform in size, the pores of the filter residue layer remain more open, allowing filtrate to pass through at a higher rate. Using coagulants to aggregate fine particles into larger clumps helps improve the filtration rate.

For suspensions where solid particles settle quickly, using filters that feed material from the top of the filter medium, aligning the filtration direction with gravity, allows coarse particles to settle, reducing clogging of the filter medium and residue layer. In difficult-to-filter suspensions (such as colloids), mixing in coarser solid particles like diatomaceous earth or expanded perlite can make the residue layer more porous. When the filtrate viscosity is high, heating the suspension can reduce viscosity. These measures can all accelerate the filtration rate.