When the filter is working, the water to be filtered enters through the nozzle, flows through the filter screen, and enters the pipeline required by the user through the outlet for process circulation. The particulate impurities in the water are trapped inside the filter screen. With such a continuous cycle, more and more particles are intercepted, and the filtering speed is slower and slower. However, the imported sewage is still continuously entering, and the filter holes will become smaller and smaller, thereby creating pressure between the inlet and the outlet. When the large difference reaches the set value, the differential pressure transmitter transmits the electrical signal to the controller, and the control system starts the drive motor to drive the shaft to rotate through the transmission assembly. At the same time, the sewage outlet is opened and discharged from the sewage outlet. After cleaning, the pressure difference drops to the minimum value, the system returns to the initial filtering state, and the system operates normally. The filter consists of a housing, a multi-element filter element, a backwash mechanism, and a differential pressure controller. The transverse partition in the shell divides the inner cavity into upper and lower cavities, and the upper cavity is equipped with multiple filter elements, which makes the filter space sufficient and significantly reduces the volume of the filter. The lower cavity is equipped with backwashing Sucker. When working, the turbid liquid enters the lower cavity of the filter through the inlet, and then enters the inner cavity of the filter element through the partition hole. The impurities larger than the gap of the filter element are intercepted, and the clean liquid passes through the gap to the upper cavity, and is finally sent out from the outlet. The filter adopts a high-strength wedge-shaped filter screen, which automatically cleans the filter element through pressure difference control and timing control. When impurities in the filter accumulate on the surface of the filter element and cause the pressure difference between the inlet and outlet to increase to the set value, or the timer reaches the preset time, the electric control box sends a signal to drive the backwash mechanism. When the backwash suction cup port is directly opposite to the filter element inlet, the drain valve is opened, and the system discharges pressure at this time. A negative pressure zone appears on the inside of the suction cup and the filter element whose relative pressure is lower than the water pressure on the outside of the filter element, forcing part of the net circulating water from the outside of the filter element. Flowing into the inner side of the filter element, the impurity particles adsorbed on the inner wall of the filter element flow into the drum with water and are discharged from the drain valve. The specially designed filter screen produces a spray effect inside the filter element, and any impurities will be washed away from the smooth inner wall. When the pressure difference between the inlet and outlet of the filter returns to normal or the timer setting time is over, the material flows continuously during the whole process, and the backwashing consumes less water, realizing continuous and automated production. Filters are widely used in the fields of metallurgy, chemical industry, petroleum, papermaking, medicine, food, mining, electric power, and urban water supply. Such as industrial wastewater, circulating water filtration, emulsion regeneration, waste oil filtration treatment, continuous casting water system in the metallurgical industry, blast furnace water system, high-pressure water descaling system for hot rolling. It is an advanced, efficient and easy-to-operate automatic filter device.

The water to be treated by the filter enters the body through the water inlet, and the impurities in the water are deposited on the stainless steel filter screen, resulting in a pressure difference. The pressure difference between the inlet and outlet is monitored by the pressure difference switch. When the pressure difference reaches the set value, the electronic controller feeds the hydraulic control valve and drives the motor signal. After the equipment is installed, the technicians will debug and set the filtration time and the cleaning conversion time. The water to be treated enters the body from the water inlet, and the filter starts to work normally. When the preset cleaning time is reached, the electric controller will give the hydraulic control valve , Drive the motor signal, trigger the following actions: the motor drives the brush to rotate to clean the filter element, while the control valve is opened to discharge the sewage. The entire cleaning process only lasts for tens of seconds. When the cleaning is over, the control valve is closed and the motor stops rotating. The system returns to its initial state and begins to enter the next filtration process. The inside of the filter housing is mainly composed of coarse filter screen, fine filter screen, suction pipe, stainless steel brush or stainless steel suction nozzle, sealing ring, anti-corrosion coating, rotating shaft and so on.

Separating the container into upper and lower chambers with filter media constitutes a simple filter. Suspension is added to the upper cavity, and enters the lower cavity through the filter medium under pressure to become filtrate. The solid particles are trapped on the surface of the filter medium to form filter residue (or filter cake). During the filtration process, the filter residue layer on the surface of the filter medium gradually thickens, the resistance of the liquid through the filter residue layer increases, and the filtration speed decreases. When the filter chamber is full of filter residue or the filtering speed is too low, stop filtering, remove the filter residue, and regenerate the filter medium to complete a filtration cycle.
The liquid must overcome the resistance to pass through the filter residue layer and the filter medium, so there must be a pressure difference on both sides of the filter medium, which is the driving force for filtering. Increasing the pressure difference can speed up the filtration, but the deformed particles under pressure will easily block the pores of the filter medium when the pressure difference is large, and the filtration will slow down instead.

Suspension filtration has three methods: filter residue layer filtration, deep layer filtration and sieving filtration.
Filtration of the filter residue layer: The filter medium can only retain large solid particles at the initial stage of filtration, and small particles pass through the filter medium with the filtrate. After the initial filter residue layer is formed, the filter residue layer plays a major role in filtering. At this time, both large and small particles are retained, such as the filtration of a plate and frame filter.

Deep filtration: the filter medium is thicker, the suspension contains less solid particles, and the particles are smaller than the pores of the filter medium. When filtering, the particles are adsorbed in the pores after entering, such as the filtration of porous plastic tube filters and sand filters.

Screening: The solid particles retained by the filter are larger than the pores of the filter medium, and the inside of the filter medium does not absorb solid particles. For example, a rotating drum filter screen filters out coarse impurities in the sewage. In the actual filtration process, the three methods often appear simultaneously or one after another.
Filtration speed

When the solid particles in the suspension are large and the particle size is uniform, the pores of the filtered filter residue layer are relatively unobstructed, and the filtrate passes through the filter residue layer at a higher speed. The application of coagulant to gather the fine particles into larger agglomerates is beneficial to increase the filtration speed.

For the suspension of solid particles with a fast sedimentation rate, apply a filter on the top of the filter medium to make the filter direction consistent with the direction of gravity. The coarse particles settle first, which can reduce the clogging of the filter medium and the filter residue layer; in the suspension that is difficult to filter ( Coarse solid particles such as diatomaceous earth and expanded perlite can be mixed into the filter residue layer to become loose; when the filtrate has a high viscosity, the suspension can be heated to reduce the viscosity. These measures can speed up the filtration speed.

Performance characteristics

1. High-efficiency and precise filtration: The filter disc filter technology with special structure has precise and sensitive performance, ensuring that only particles smaller than the required size can enter the system. It is the most effective filtration system; specifications are 5μ, 10μ, 20μ, 55μ, 100μ, 130μ, 200μ, etc., users can choose filter discs with different precisions according to water requirements. The system flow can be flexibly adjusted according to needs.

2. Standard modularity, saving space: The system is based on standard disc filter unit, according to modular design, users can choose according to their needs, flexible and changeable, strong interchangeability. The system is compact and occupies a very small area. The corner space can be flexibly used for installation. For example, the equipment with a processing water volume of about 300m3/h occupies only about 6m2 (general water quality, filtration level 100μ).

3. Fully automatic operation and continuous water discharge: The backwashing process alternates between each unit in the filter combination, and the working and backwashing states are automatically switched to ensure continuous water discharge; the backwashing water consumption is very small, only It accounts for 0.5% of the water output; if combined with air-assisted backwashing, the self-consumption water can be reduced to less than 0.2%. High-speed and thorough backwashing can be completed in just tens of seconds

4. Long life: the new plastic filter element is sturdy, non-wearing, non-corrosive, and minimally fouling. After years of industrial practical verification, it will not wear out after 6-10 years of use, will not age, and the filtering and backwashing effects will not be affected by use. Time has become worse.

5. High quality, low maintenance: The products meet the corresponding quality standards. All products are tested and run under simulated working conditions before leaving the factory. No special tools are required, and there are few parts. It is easy to use and only requires regular inspections. Daily maintenance is required. 

Selection principle

1. Import and export path:
In principle, the inlet and outlet diameter of the filter should not be smaller than the inlet diameter of the matching pump, and it is generally the same as the inlet pipe diameter.
2. Nominal pressure:
Determine the pressure level of the filter according to the highest pressure that may appear in the filter line.
3. Selection of the number of holes:
The main consideration is the particle size of the impurity to be intercepted, which is determined according to the process requirements of the medium process. The particle size that can be intercepted by various specifications of screens can be found in the following table "Filter Specifications".
4. Filter material:
The material of the filter is generally the same as the material of the connected process pipeline. For different service conditions, you can consider choosing a filter made of cast iron, carbon steel, low alloy steel or stainless steel.
5. Calculation of filter resistance loss
For water filters, the pressure loss is 0.52~1.2kpa under the general calculation of the rated flow rate