The sludge hopper is mainly used in the sludge dewatering room to collect the dewatered mud cake and store it in the hopper. When the sludge reaches a certain volume, the valve at the bottom of the hopper is opened by control, and the sludge cake is discharged to the truck for transportation. There are two fan doors at the bottom of the sludge hopper to collect and discharge the sludge by controlling the two doors, the fan doors are controlled by pneumatic cylinders or electric actuators.