Large-scale vertical centrifugal pump in operation, there is vibration, the upper and lower bearings are often hot, damaged, and even pump shaft and bearing connections wear. Pump instability, affecting the normal water supply, the need for its damping control.
First, the pump vibration analysis
1, domestic vertical pump 28SLA-10 is a direct transformation from the horizontal pump. The vertical height between the motor base and the pump base is 4.3m and the drive shaft weighs 3t. Compared with the horizontal pump, it adds a length of 3752mm diameter 140mm intermediate drive shaft. In the structure, in addition to the middle drive shaft with a bearing, without any modification. The four pumps long-term operating pressure of 0.7 ~ 0.85MPa. In the high head, flow conditions, such a high center of gravity, high-quality system of high-speed rotation, the centrifugal force is great, will cause greater vibration of the unit. Coupled stent and pump out of the water connection stiffness is not enough, resulting in a large displacement of the pump and the connector. Displacement of the pump during operation results in a change in the bearing condition of the bearing. As the vibration increases, it is easy to generate heat. If the correction of displacement pump to improve bearing stress conditions, can reduce the vibration of the system.
2, rigid connection between pump and drive shaft. Due to manufacturing and installation reasons, the pump shaft is concentric with the drive shaft during operation, causing the pump to vibrate. The vibrations generated by motors, transmission shafts and other sources are also directly transmitted to the pump to form a superposition of vibrations to further increase the vibration of the pump. In addition, this rigid connection to increase the water pump bearing the external force, resulting in easy to heat the bearing, affecting the pump shaft.
Second, the pump transformation
For the above reasons, we have taken the following two steps to transform.
1, to strengthen the pipeline stiffness. Taking into account the more difficult for the pump to strengthen, take the outlet pipe in the pump welding "stiffener" approach. Along the direction of inlet and outlet water, flanges at both ends of the connection pipe between the outlet pipe and outlet valve at the outlet of the water pump are welded with 8 steel plates with a thickness of 32mm and a width of 100mm. Increase the stiffness of the steel pipe to reduce the amount of deformation, resistance to pump displacement. After measuring, stiffened, the displacement of pump A point dropped to 0.35mm.
2, the transformation of the transmission system. In order to reduce the motor, the vibration of the transmission shaft is transmitted to the water pump, and the rigid connection between the water pump and the transmission shaft is changed to the elastic connection. Use GB4323-84 elastic sleeve pin coupling, centrifugal pump maximum compensation displacement of 0.6mm, compensation angle of 1 ° 30 ?. In this way, the vibration of the motor and drive shaft can be compensated by the flexible coupling, and the vibration can not be directly transmitted to the pump.
Third, the transformation results
After the transformation, measured by the vibration of the pump before the transformation from 4.3cm / s reduced to 1.48cm / s. According to the vibration intensity standard ISO2372-1974 can determine that the pump is running in the best area. At the same time, the pump runs smoothly, the bearings only need normal maintenance, and the shaft of the pump is worn out, indicating that the reform is successful.
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