When the system is in the filtering state, the unfiltered water passes through the upper water distributor, cooperates with the spherical shell, and reaches the packing layer in the filter in a state of nearly advection. When water flows through the packing layer, impurities are trapped within the packing layer. The collector at the bottom of the filter collects the filtered water evenly and flows out. Advection filtration determines that the filter can still achieve good filtration effect under high flow rate.
As impurities continue to accumulate in the packing layer, the head loss (ie differential pressure) will continue to increase. When the pressure difference reaches a certain set limit or the filtration time reaches the set value, the system will automatically switch to the backwashing state to clean the packing layer and remove accumulated impurities. For the system, regular backwashing is required to remove Accumulated impurities are necessary.
When the system enters the backwash state, the on-off position of the three-way valve is changed through PLC control (the inlet is closed, the sewage port is opened), and the filtered water in other filter tanks flows into the filter tank to be backwashed. The packing layer of the filter unit backwashed by the system pressure is washed up under the impact of the water flow, and the impurities are discharged through the sewage outlet of the three-way valve.