The Vibration and Vibration Reduction of the Vertical Multi-stage Centrifugal Pump in Huali Pump Co., Ltd. Changsha Multistage Centrifugal Pump Plant
Abstract: Changsha multi-stage centrifugal pump manufacturers Hua Li pump industry in the process of operation of the multi-stage centrifugal pump , vibration, the upper and lower bearing often fever, damage, and even the pump shaft and bearing wear and other issues to reduce vibration .
Keywords: multi-stage centrifugal pump Changsha multi-stage pump Changsha multi-stage centrifugal pump
 Vertical multi-stage centrifugal pump in the process of operation, there is a large vibration, the upper and lower bearings often heat, damage, and even the pump shaft and bearing connection parts wear. The multi-stage centrifugal pump is unstable in operation and affects normal water supply, and it needs to be damped and treated.
    One, multi-stage centrifugal pump vibration analysis
1. The vertical multi-stage centrifugal pump 28SLA-10 is directly transformed from the horizontal pump. The vertical height between the motor base and the multi-stage centrifugal pump base is 4.3m , and the drive shaft weighs 3t . Compared to the horizontal multi-stage centrifugal pump, it added an intermediate shaft with a length of 3752 mm and a diameter of 140 mm . Structurally, no modifications were made except to add a bearing to the intermediate drive shaft. The operating pressure of this four-stage multistage centrifugal pump is 0.7 to 0.85 MPa for a long time. In the condition of high head and high flow rate, such a system with high center of gravity and high mass rotation will produce large centrifugal force, which will cause large vibration of the unit. In addition, the connection rigidity of the bracket and the multi-stage centrifugal pump in and out of the water is not enough, resulting in a large displacement of the vertical multi-stage centrifugal pump and each connecting member. The displacement of the vertical multi-stage centrifugal pump during operation results in a change in the bearing's stress condition and increased vibration, making it prone to heat. If the displacement of the multi-stage centrifugal pump is corrected and the bearing condition is improved, the vibration intensity of the system can be reduced.
2. Rigid connection between vertical multi-stage centrifugal pump and transmission shaft. Due to manufacturing and installation reasons, the pump shaft is concentric with the drive shaft during operation, resulting in vibration of the vertical multi-stage centrifugal pump; the vibration generated by the motor, transmission shaft, and other sources is also directly transmitted to the multi-stage centrifugal pump, forming a superposition of vibration and further increasing the vibration. Most of the centrifugal pumps vibrate. In addition, this rigid connection increases the external forces experienced by the bearings on the vertical multi-stage centrifugal pumps, resulting in the bearings being prone to heat and affecting the pump shaft.
    Second, the transformation situation
    For the above reasons, we have taken the following two steps to transform.
1 , to strengthen the pipe stiffness. Considering that it is difficult to reinforce a multi-stage centrifugal pump, a method of welding "reinforcement ribs" at the outlet of a multi-stage centrifugal pump is adopted. In the direction of water flow in and out of the multi-stage centrifugal pump outlet expansion pipe and outlet valve between the two ends of the steel pipe flange, with 8 thickness of 32mm , a width of 100mm steel plate welding. Increase the rigidity of the steel pipe, reduce the deformation, and resist the displacement of the multi-stage centrifugal pump. After measurement, after the reinforcement, the displacement of point A of the multistage centrifugal pump was reduced to 0.35mm .
2. Transform the transmission system. In order to reduce the vibration of the motor and transmission shaft to the multi-stage centrifugal pump, the rigid connection between the multi-stage centrifugal pump and the transmission shaft is changed into elastic connection. Use GB4323-84 elastic sleeve pin coupling, centrifugal pump large compensation displacement is 0.6mm , compensation angle is 1 ° 30?. In this way, the vibration of the motor and the transmission shaft can be compensated by the elastic coupling and not directly transmitted to the multi-stage centrifugal pump .
    Third, the transformation results
    After the transformation, the vibration of the multi-stage centrifugal pump was reduced to 1.48 cm/s from the pre-transformation vibration speed of 4.3 cm/s . According to the vibration intensity standard ISO2372-1974, it can be determined that the multi-stage centrifugal pump operates in an excellent area. At the same time, the multi-stage centrifugal pump runs smoothly, the upper bearing only needs normal maintenance, and the pump shaft is worn out, which means that the transformation is successful.
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