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Vibration analysis of horizontal multistage pump
Source:未知|Popularity:0|release date:2020-03-19 15:57:06
Working principle of horizontal multistage centrifugal pump:
The multistage centrifugal pump is to string two or more single-stage impellers with the same function on the same shaft, and then the fluid is forced out to the outlet of the pump through the flow passage, so as to obtain a higher outlet pressure head. Such a structure of series connection and superposition of energy forms a multistage centrifugal pump.
First of all, in the design of horizontal multistage centrifugal pump, the shaft vibration is allowed by the pump itself, and its vibration value is less than 0.051mm (the value is determined according to the rotation speed and center height of the pump). Most of the pump types in the industry like multistage pump conform to JB / t 8097 standard. If the vibration value of a pump is within the range, it is normal. What is the cause of the vibration of this multistage pump? The causes are as follows:
1. The inlet air (air leakage) of the water pump causes the pump to make abnormal noise after half idle running, and then the pump starts to vibrate.
2. In the water pump, foreign matters enter into the runner of the impeller or fine particles get stuck in the seal and wear, and then the mating surface of parts and parts is damaged. As a result, the pressure difference between the front cover plate and the rear cover plate of the impeller is unbalanced, which leads to the development of the pump from axial displacement to pump vibration. After that, this kind of vibration is generally more serious, which will cause the foundation bolts of the pump base to loosen, leading to the foundation problems.
3. The pump shaft is not concentric with the motor shaft, which will cause the drive bearing to heat up and vibrate in a short time, and start to wear the bearing. When the fatigue strength of the shaft reaches the limit, the shaft will be broken back.
4. Due to the unreasonable selection of pump, the cavitation performance deviation of pump will be caused. Once cavitation occurs in the pump, a lot of air bubbles will be generated inside the pump and break at the inlet or outlet of impeller. When the air bubbles break, the potential energy concentrated in the pump will be released at the inlet or outlet of continuous impeller, and the water flow in the flow passage of pump will be disordered. When the disordered liquid cannot be pressed for a long time The original rule is to exercise. Directly reflected in the outside of the pump is the vibration.
5. Because of the unbalance of the rotor parts, the vibration of the pump is caused.
6. For machining problems of all parts, due to strict requirements of tolerance at all levels of mechanical parts, there are unqualified parts mixed in during inspection of all parts.
7. In the design, the critical speed of the pump does not meet the design standard. When the pump shaft is running at high speed, our pump shaft has a natural frequency.
The multistage centrifugal pump is to string two or more single-stage impellers with the same function on the same shaft, and then the fluid is forced out to the outlet of the pump through the flow passage, so as to obtain a higher outlet pressure head. Such a structure of series connection and superposition of energy forms a multistage centrifugal pump.
First of all, in the design of horizontal multistage centrifugal pump, the shaft vibration is allowed by the pump itself, and its vibration value is less than 0.051mm (the value is determined according to the rotation speed and center height of the pump). Most of the pump types in the industry like multistage pump conform to JB / t 8097 standard. If the vibration value of a pump is within the range, it is normal. What is the cause of the vibration of this multistage pump? The causes are as follows:
1. The inlet air (air leakage) of the water pump causes the pump to make abnormal noise after half idle running, and then the pump starts to vibrate.
2. In the water pump, foreign matters enter into the runner of the impeller or fine particles get stuck in the seal and wear, and then the mating surface of parts and parts is damaged. As a result, the pressure difference between the front cover plate and the rear cover plate of the impeller is unbalanced, which leads to the development of the pump from axial displacement to pump vibration. After that, this kind of vibration is generally more serious, which will cause the foundation bolts of the pump base to loosen, leading to the foundation problems.
3. The pump shaft is not concentric with the motor shaft, which will cause the drive bearing to heat up and vibrate in a short time, and start to wear the bearing. When the fatigue strength of the shaft reaches the limit, the shaft will be broken back.
4. Due to the unreasonable selection of pump, the cavitation performance deviation of pump will be caused. Once cavitation occurs in the pump, a lot of air bubbles will be generated inside the pump and break at the inlet or outlet of impeller. When the air bubbles break, the potential energy concentrated in the pump will be released at the inlet or outlet of continuous impeller, and the water flow in the flow passage of pump will be disordered. When the disordered liquid cannot be pressed for a long time The original rule is to exercise. Directly reflected in the outside of the pump is the vibration.
5. Because of the unbalance of the rotor parts, the vibration of the pump is caused.
6. For machining problems of all parts, due to strict requirements of tolerance at all levels of mechanical parts, there are unqualified parts mixed in during inspection of all parts.
7. In the design, the critical speed of the pump does not meet the design standard. When the pump shaft is running at high speed, our pump shaft has a natural frequency.