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Working principle of stainless steel multi bag filter housing

Time : 2023-06-28 Hits : 3

When the rust steel multi bag filter housing works, the water to be filtered enters from the water inlet, flows through the filter screen, and enters the pipeline required by the user through the outlet for process circulation, and the particle impurities in the water are intercepted in the filter screen. With such continuous circulation, more and more particles are intercepted, and the filtration speed is slower and slower, while the imported sewage still enters continuously, and the filter hole will be smaller and smaller, resulting in a pressure difference between the inlet and outlet. When the difference reaches the set value, the differential pressure transmitter transmits an 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 drain outlet is opened and discharged from the drain outlet, When the filter screen is cleaned, the differential pressure drops to the small value of Zui, the system returns to the initial filtration state, and the system operates normally. The filter is composed of a shell, a multi-element filter element, a backwashing mechanism, and a differential pressure controller. The diaphragm plate in the shell divides its inner cavity into upper and lower cavities. The upper cavity is equipped with multiple filter elements, which makes the filtering space full and significantly reduces the volume of the filter. The lower cavity is equipped with a backwash suction cup. During operation, the turbid liquid enters the lower chamber of the filter through the inlet, and then enters the inner chamber of the filter element through the diaphragm hole. Impurities larger than the gap of the filter element are intercepted, and the purified liquid passes through the gap to the upper chamber and is sent out from the outlet after Zui. The filter adopts high-strength wedge-shaped filter screen, which automatically cleans the filter element through differential pressure control and timing control. When the impurities in the filter accumulate on the surface of the filter element, causing the inlet and outlet differential pressure 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 inlet of the backwash suction cup is aligned with the inlet of the filter element, the blowdown valve is opened. At this time, the system releases pressure and discharges water. There is a negative pressure area with a relative pressure lower than the water pressure outside the filter element inside the suction cup and the filter element, forcing part of the net circulating water to flow into the inside of the filter element from the outside of the filter element. The impurity particles adsorbed on the inner wall of the filter element flow into the pan with water and are discharged from the blowdown 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 ends, the flow of materials is not cut off in the whole process, and the backwashing water consumption is less, realizing continuous and automatic production. Filters are widely used in metallurgy, chemical industry, petroleum, papermaking, medicine, food, mining, electric power and urban water supply. Such as industrial wastewater, filtration of circulating water, regeneration of emulsion, filtration and treatment of waste oil, continuous casting water system and blast furnace water system in metallurgical industry, and high-pressure water descaling system for hot rolling. It is an advanced, efficient and easy to operate full-automatic filtering device. The water to be treated by the filter enters the body from the water inlet, and the impurities in the water are deposited on the stainless steel filter screen, resulting in a differential pressure. Monitor the change of inlet and outlet differential pressure through the differential pressure switch. When the differential pressure reaches the set value, the electric controller sends a signal to the hydraulic control valve to drive the motor. After the equipment is installed, the technicians will debug it, set the filtration time and cleaning conversion time, the water to be treated enters the body from the water inlet, and the filter begins to work normally. When the preset cleaning time is reached, the electric controller will send signals to the hydraulic control valve and drive the motor, causing the following actions: the motor drives the brush to rotate, cleans the filter element, and the control valve is opened for sewage discharge. The whole cleaning process only lasts for dozens of seconds, When the cleaning is finished, close the control valve, the motor stops rotating, and the system returns to its initial state to start the next filtration process. The shell of the filter is mainly composed of coarse filter screen, fine filter screen, sewage suction pipe, stainless steel brush or stainless steel suction nozzle, sealing ring, anti-corrosion coating, rotating shaft, etc. A simple filter is formed by separating the container into upper and lower cavities with filter media. The suspension is added into the upper chamber and enters the lower chamber through the filter medium under pressure to become filtrate. Solid particles are intercepted 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 is gradually thickened, the resistance of the liquid passing through the filter residue layer increases, and the filtration speed decreases. When the filter chamber is full of filter residue or the filtration speed is too small, stop filtration, remove the filter residue, and regenerate the filter medium to complete a filtration cycle. The liquid must overcome the resistance when passing 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 to realize filtration. Increasing the pressure difference can accelerate the filtration, but the deformed particles after pressure are easy to block the pores of the filter medium when the pressure difference is large, and the filtration slows down instead. There are three ways of suspension filtration: residue layer filtration, deep filtration and screen filtration. ① Filtration of filter residue layer: at the initial stage of filtration, the filter medium can only intercept large solid particles, and small particles pass through the filter medium with the filtrate. After the formation of the initial filter residue layer, the filter residue layer plays a major role in filtration. At this time, both large and small particles are intercepted, such as the filtration of the plate and frame filter press. ② Deep filtration: the filter medium is thick, the suspension contains less solid particles, and the particles are smaller than the pores of the filter medium. During filtration, the particles are absorbed in the pores after entering, such as the filtration of porous plastic pipe filter and sand filter. ③ Screen filtration: the solid particles retained by filtration are larger than the pores of the filter medium, and the solid particles are not adsorbed inside the filter medium. For example, the rotary drum filter screen filters out the coarse impurities in the sewage. In the actual filtering process, the three methods often appear simultaneously or successively.

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