How centrifugal pumps work

When the centrifugal pump is started, the pump shaft drives the impeller together to perform a high-speed rotary motion, forcing the liquid to be pre-filled to rotate between the blades. Under the action of the inertial centrifugal force, the liquid moves radially from the center of the impeller to the periphery. The liquid gains energy during the movement through the impeller, the static pressure increases, and the flow rate increases. When the liquid leaves the impeller and enters the centrifugal pump casing, it decelerates due to the gradual enlargement of the flow passage in the casing, and part of the kinetic energy is converted into static pressure energy, and finally flows into the discharge pipeline in a tangential direction. Therefore, the scroll casing is not only a component that collects the liquid that flows from the impeller, but also a turning device. When the liquid is thrown from the center of the impeller to the periphery, the center of the impeller forms a low-pressure zone. Under the action of the total potential energy difference between the liquid level of the storage tank and the impeller, the liquid is sucked into the center of the impeller. With the continuous operation of the impeller, the liquid is continuously sucked in and discharged. The mechanical energy obtained by the liquid in the centrifugal pump eventually manifests itself as an increase in static pressure energy.

The function of the impeller is to directly transfer the mechanical energy of the prime mover to the liquid to increase the static pressure energy and kinetic energy of the liquid (mainly increase the static pressure energy).

1. Impeller The role of the impeller is to transfer the mechanical energy of the prime mover directly to the liquid to increase the hydrostatic energy and kinetic energy of the liquid (mainly increasing static pressure energy). There are three kinds of impeller: open, semi-closed and closed. The open impeller has no cover plate on both sides of the blade, so it is simple to manufacture and easy to clean. It is suitable for conveying materials containing a large amount of suspended solids. The efficiency is low and the liquid pressure is not high; the semi-closed impeller has no cover on the inlet side. The plate, on the other side, has a cover plate, suitable for conveying materials that are easy to precipitate or contain particles, and has low efficiency; the closed impeller has front and rear cover plates on both sides of the blade, which is high in efficiency and is suitable for conveying without impurities Cleaning liquid. The general centrifugal pump impeller is mostly this type.

2. The function of the pump casing is to confine the impeller in a certain space so that the liquid can be sucked in and pressed out by the action of the impeller. Centrifugal pump casing made of more volute shape, it is also known as volute. As the cross-sectional area of ​​the flow channel gradually expands, the high-velocity liquid thrown from the impeller gradually reduces the flow velocity, so that part of the kinetic energy is effectively converted into static pressure energy. The pump casing not only collects the liquid thrown by the impeller, but is also an energy conversion device.