How the filter works

The process cycle is carried out through the outlet into the piping required by the user, and particulate impurities in the water are trapped inside the screen. With such continuous circulation, more and more particles are trapped, the filtration speed is getting slower and slower, and the imported sewage is still entering continuously, and the filter holes will become smaller and smaller, thereby generating pressure between the inlet and outlet. Poor, 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 component, and the sewage outlet opens, and is discharged by the sewage outlet. After the cleaning is completed, the pressure difference is reduced to the minimum value, the system returns to the initial filtration state, and the system operates normally. The filter is composed of a casing, a multi-element filter, a backwashing mechanism, and a differential pressure controller. The diaphragm in the housing divides the inner cavity into upper and lower chambers, and the upper chamber is provided with a plurality of filter cores, so that the filtering space is sufficient, the volume of the filter is significantly reduced, and the back chamber is installed with backwashing. Suction cup. During operation, the turbid liquid enters the lower cavity of the filter through the inlet, and enters the inner cavity of the filter element through the partition hole. Impurities larger than the gap of the filter core are trapped, the clean liquid passes through the slit to the upper chamber, and finally is sent out from the outlet. The filter uses a high-strength wedge filter to automatically clean the filter element by differential pressure control and timing control. When the impurities in the filter accumulate on the surface of the filter element and the differential pressure between the inlet and outlet increases to a set value, or the timer reaches a preset time, the electric control box sends a signal to drive the backwashing mechanism. When the backwashing suction port is directly opposite to the filter inlet, the drain valve is opened. At this time, the system is drained, and a negative pressure zone is formed on the inside of the suction cup and the filter core, which is lower than the water pressure outside the filter, forcing part of the circulating water from the outside of the filter. The inside of the filter element flows into the inside of the filter element, and the foreign particles adsorbed on the inner wall of the filter element flow into the tray with water and are discharged from the drain valve. The specially designed filter screen creates a jetting 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 continues to flow during the whole process, and the backwash consumes less water, realizing continuous and automated production. Filters are widely used in metallurgy, chemical, petroleum, paper, medicine, food, mining, electric power, urban water supply. Such as industrial wastewater, filtration of circulating water, regeneration of emulsion, filtration of waste oil, continuous casting water system in metallurgical industry, blast furnace water system, high-pressure water descaling system for hot rolling. It is an advanced, efficient and easy to operate fully automatic filtration device.
The water to be treated by the filter enters the body through the water inlet, and impurities in the water are deposited on the stainless steel filter screen, thereby generating a pressure difference. The pressure difference switch is used to monitor the pressure difference between the inlet and outlet. When the pressure difference reaches the set value, the electric controller supplies the hydraulic control valve to drive the motor signal. After the equipment is installed, the technician will debug and set the filtration time and cleaning conversion time. The water to be treated enters the body through the water inlet, and the filter starts to work normally. When the preset cleaning time is reached, the electric controller gives the hydraulic control valve. Driving the motor signal, triggering the following actions: the motor drives the brush to rotate, and the filter element is cleaned. At the same time, the control valve is opened for sewage discharge. The entire cleaning process only lasts for several tens of seconds. When the cleaning is finished, the control valve is closed and the motor stops rotating. The system returns to its initial state and begins the next filtration process. The inside of the filter casing is mainly composed of a coarse filter mesh, a fine filter mesh, a suction pipe, a stainless steel brush or a stainless steel nozzle, a sealing ring, an anti-corrosion coating, a rotating shaft and the like.
Separating the container into upper and lower chambers with a filter medium constitutes a simple filter. The suspension is added to the upper chamber and enters the lower chamber through the filter medium under pressure to form a filtrate, and the solid particles are trapped on the surface of the filter medium to form a filter residue (or filter cake). During the filtration process, the filter residue layer on the surface area of ​​the filter medium is gradually thickened, and the resistance of the liquid passing through the filter residue layer is increased, and the filtration speed is decreased. When the filter chamber is filled with filter residue or the filtration speed is too small, the filtration is stopped, the filter residue is removed, and the filter medium is regenerated to complete a filtration cycle.
The liquid must pass through the filter cake layer and the filter medium to overcome the resistance, so there must be a pressure difference on both sides of the filter medium, which is the driving force for the filtration. Increasing the pressure difference can accelerate the filtration, but the particles deformed under pressure tend to block the pores of the filter medium when the pressure is large, and the filtration is slowed down.
The suspension is filtered by three methods: filter layer filtration, depth filtration and sieve filtration.
1 Filter layer filtration: In the initial stage of filtration, the filter medium can only retain large solid particles, and the small particles pass through the filter medium with the filtrate. After the formation of the initial filter cake layer, the filter cake layer plays a major role in the filtration, at which time both large and small particles are trapped, such as filtration by a plate and frame filter press.
2Deep 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 filtration of a porous plastic tube filter or a sand filter.
3 Screening: The solid particles retained by the filtration are larger than the pores of the filter medium, and the inside of the filter medium does not adsorb solid particles, for example, the rotary filter screen filters out coarse impurities in the sewage. In the actual filtration process, the three methods often occur simultaneously or sequentially.
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