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Diagram of Centrifugal Pump Structure

09 Sep 2021Email

Centrifugal pumps are widely used and widely used. In addition to industrial applications, centrifugal pumps are also widely used in agricultural irrigation, municipal water supply, circulating water supply in power stations, and urban pollution treatment. There are many types of centrifugal pumps. Although the structures of various types of pumps are different, the main components are basically the same. Now we mainly introduce the basic structure of centrifugal pumps.

multistage pump

   The basic structure of a centrifugal pump is composed of eight parts: impeller, pump body, pump cover, water retaining ring, pump shaft, bearing, sealing ring, stuffing box, and axial force balance device.

1. The impeller is the working part of the centrifugal pump. It is one of the important parts of the centrifugal pump to realize the liquid transportation by relying on its high-speed rotation to do work on the liquid. The impeller is generally composed of three parts: wheel, blade and cover. The cover of the impeller is divided into a front cover and a rear cover. The cover on the side of the impeller mouth is called the front cover, and the cover on the other side is called the rear cover. The stainless steel impeller produced by Zhonglian Pump is made of standard 304 material, using the most advanced stainless steel plate stamping forming and laser welding technology. After the stainless steel plate is stamped, it is directly welded by laser precision.

When the centrifugal pump is started, the pump shaft drives the impeller to rotate at a high speed, forcing the pre-filled liquid between the blades to rotate. Under the action of inertial centrifugal force, the liquid moves radially from the center of the impeller to the outer periphery. The liquid gains energy in the process of moving through the impeller, the static pressure energy increases, and the flow velocity increases. When the liquid leaves the impeller and enters the pump casing, it slows down due to the gradual expansion 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.

2. The pump body is also called the pump housing, which is the main body of the water pump. Play a supporting and fixing role, and connect with the bracket for mounting the bearing. The volute refers to a spiral flow passage with a gradually increasing cross-sectional area from the impeller outlet to the next stage impeller inlet or to the pump outlet pipe. The flow channel gradually expands, and the outlet is a diffuser tube. After the liquid flows out of the impeller, its flow rate can be gently reduced, so that a large part of the kinetic energy is converted into static pressure energy.

3. The function of the pump shaft is to connect the motor with the coupling, and transmit the torque of the motor to the impeller, so it is the main component for transferring mechanical energy. One end of it is connected with the motor shaft through a coupling, and the other end supports the impeller for rotating motion. The shaft is equipped with components such as bearings and axial seals.

4. The role of the shaft sleeve is to protect the pump shaft, so that the friction between the packing and the pump shaft is transformed into the friction between the packing and the shaft sleeve, so the shaft sleeve is an easy-wear part of the centrifugal pump.

5. The bearing plays the role of supporting the weight and bearing force of the rotor. Rolling bearings are mostly used in centrifugal pumps. The outer ring and the bearing seat hole adopt the base shaft system, and the inner ring and the rotating shaft adopt the basic hole system. The national standards of the matching category have recommended values ​​and can be selected according to specific conditions. Bearings are generally lubricated with grease and lubricating oil.

6. The guide wheel is a fixed disk. The front side has forward guide vanes wrapped around the outer edge of the impeller. These guide vanes form a diffuse flow channel. Guide leaf. After the liquid is thrown out from the impeller, it enters the guide wheel gently, and continues to flow outward along the forward guide vane. The speed gradually decreases, and most of the kinetic energy is converted into static pressure energy.

7. The sealing ring is also called the leakage reducing ring. In order to reduce internal leakage and protect the pump casing, a removable sealing ring is installed on the casing corresponding to the entrance of the impeller.

8. The stuffing box is mainly made of packing, which prevents the water flow in the pump from flowing outside and the outside air from entering the pump. Always maintain the vacuum in the pump! When the pump shaft rubs against the packing to generate heat, it is necessary to inject water into the water seal ring by the water seal pipe to cool the packing!

9. Axial force balancing device. During the operation of the centrifugal pump, because the liquid enters the impeller under low pressure and flows out under high pressure, the pressure on both sides of the impeller is unequal, and the axial thrust directed to the inlet direction is generated. It will cause the rotor to move in the axial direction, causing wear and vibration. Therefore, an axial thrust bearing should be installed to balance the axial force.

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