The sizing pump is also called the flushing pump. It is a centrifugal pump specially used to transport low-concentration (≤1%) pulp to the headbox of the paper machine. It can be known from the characteristics of the centrifugal pump that the lift has a certain pulsation. This has a certain and sometimes even impact on high-speed papermaking machines. The pulsation of pulp feeding will cause periodic changes in the basis weight of the paper web produced in the longitudinal direction.
In order to reduce the pulsation of the pulsation pump, a single-stage double-suction mid-open structure is adopted, and the impellers are designed as double-suction closed type with a partition in the middle. The blades on both sides are staggered by half the blade pitch, and the exit edge of the blade forms an oblique angle with the center line of the impeller; there are many impeller blades, and there are 6-12 pieces on each side according to the size of the impeller. Dynamic balance. The characteristics of the pump body of the flushing pump: a separation tongue is formed at the connection between the volute chamber of the pump body and the slurry pipe. The tongue is designed in a V shape, so that the separating tongue can gradually cut into the impeller, and the influence of the separating tongue on the pressure pulsation can be further reduced.
The sizing pump has the task of mixing the pulp evenly. Its suction port is connected to the bottom of the liquid level of the flushing water return tank, and the matched pulp is introduced from the side pipe of the return pipe. In order to achieve uniform mixing, the flow rate of the pulp should be higher than that of the return water. Generally not less than 3-4.5m/s.