What is the structure and working principle of a centrifugal pump?

Structure of centrifugal pump

 

Centrifugal pumps are most widely used in chemical production because of their wide performance range (including flow rate, pressure head and resistance to medium properties), small size, simple structure, easy operation, uniform flow rate, few accidents, long life, low purchase and operation costs, and other outstanding advantages.

1. Basic structure of centrifugal pumps

The basic components of a centrifugal pump are a high-speed rotating impeller and a fixed snail-shaped pump casing. The impeller with several (usually 4 to 12) backward curved blades is fastened to the pump shaft and driven by the motor to rotate at high speed along with the pump shaft. The impeller is a component that directly works on the liquid in the pump and is the energy supply device of the centrifugal pump. The suction port in the center of the pump casing is connected to the suction pipeline, and a one-way bottom valve is installed at the bottom of the suction pipeline. The discharge port on the side of the pump casing is connected to the discharge pipeline equipped with a regulating valve.

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2. Working principle of centrifugal pump
When the centrifugal pump is started, the pump shaft drives the impeller to rotate at high speed, forcing the liquid pre-filled between the blades to rotate. Under the action of inertial centrifugal force, the liquid moves radially from the center of the impeller to the periphery. The liquid gains energy in the process of flowing through the impeller, the static pressure energy increases, and the flow rate increases. When the liquid leaves the impeller and enters the pump casing, it slows down due to the gradual expansion of the flow channel in the casing, and part of the kinetic energy is converted into static pressure energy, and finally flows into the discharge pipeline along the tangential direction. Therefore, the volute pump casing is not only a component that collects the liquid flowing out of the impeller, but also an energy conversion device. When the liquid is thrown from the center of the impeller to the periphery, a low-pressure area is formed in the center of the impeller. Under the action of the total potential energy difference between the liquid surface of the storage tank and the center of the impeller, the liquid is sucked into the center of the impeller. Relying on 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 is ultimately manifested as an increase in static pressure energy.