Sudden drops and rises in vibration of high-speed centrifugal pumps
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During the switching process of the inlet feed tank in a high-speed pump, there are sudden drops and rises in vibration. What could be the possible reasons?
Are there significant changes in the temperature and density of the material?
It is recommended to bring out all other process factors as well and evaluate them comprehensively. One cannot judge the reasons by looking at this trend line alone.
This post was last edited by Lao Wu Set on 2020-9-20 at 17:23. The original poster is really concise with their words; assuming that the PIC5802 is the return control valve for the minimum flow rate of the high-speed pump: 1. Before switching the feed tank, the opening degree of the return control valve is close to fully closed, indicating that it is difficult for the high-speed pump to increase the flow rate, so action should be taken to switch tanks. 2. After the tank is changed, the pressure head increases and the flow rate rises; the opening degree of the return control valve automatically returns to around 10%, and the vibration decreases. 3. The minimum flow set value was artificially increased, causing the return control valve to open automatically to around 15%, which led to an increase in vibration. For operational recommendations, a low pressure alarm should be installed at the pump inlet, the minimum flow rate should be fixed according to the design, and the opening degree of the manual return control valve should be set at 10%. It is the optimal operating condition for this high-speed pump.
The original poster is very concise in his writing, while the five brothers’ comments are each wordful of value; their analyses are logical and thorough – they’re definitely experienced pros!
Some of the analyses I did on my own don’t seem to hit the mark.
After reviewing your additional materials, if your issue remains unresolved, I recommend that you investigate the pumps at the payment tank area on site.
Okay, thank you. I’ll go to the site and look more carefully for the reason.
During the transition of the feed tank at the inlet, a temporary decrease in the inlet flow rate led to vibration fluctuations caused by vacuum formation at the inlet
The information available is indeed limited. 1. Around 10:00 to 11:00 on September 15, the opening degree of the return valve reached a state where it was almost completely closed, which is different from previous switching scenarios; this warrants attention, as abnormalities in pump operation had already appeared prior to that switching. 2. Possible areas for investigation include whether there are any valve controls affecting the rear processing unit, the impact of temperature, and whether the inlet manual valve has been moved； 3. Additionally, the inlet filter and the outlet check valve should be inspected carefully, especially the outlet check valve; it is also possible to tap it during operation to see if it has a significant impact on vibrations ； 4. Monitor the pump shaft temperature, especially for a period of time before and after the switchover.