Originally posted by mkota:
We have a three impeller horizontal centrifugal BFW pump driven by motor through gear coupling. The pump was commissioned in 1992. Since than this pump is having problem of high vibrations. Particularly in vertical. Amplitude remains in the range of 70 to 100 and velocity from 9 to 15. Trial had been done as suggested by many experts but there was no improvement. Line tension, balancing, bearings, Lubrication etc. are the critaria tried. Please suggest if any thing can be done.
You please check coasting down of the pump. There you will get resonance frequency if at all. You can try with this solution
Increase rigidity of the base frame by regrouting or more rigid base frame of the pump.
Inthe coasting down spctrum at certain frequency vibration level will increase just like anything & at that time there will be 180 degree phase change.
If possible you can reduce the bearing distance span by modifying journal of the shaft.
hope it will help you. If any further clarification required send mail firstname.lastname@example.org