This case study is about Dynamic Balancing of Cement Mill Separator Fan at a leading Cement plant in Kuwait.
Equipment Name: Cement Mill-3 Separator Fan
Rated Speed: 950 RPM
Motor Power: 400 KW
VTS was first called for Vibration diagnosis and Dynamic Balancing in January 2021 as It was indicating increased vibration level at Motor bearings. FFT indicates predominant 1X. Dynamic balancing of the rotor was performed by adding a correction mass of 193 grams. The overall vibration level after Balancing was well within the allowable limit.
The Fan rotor was replaced with a new one in a scheduled PM plan in July 2021. Vibration level was observed to be on higher side once again and indicating unbalance symptoms. Hence, the dynamic balancing was performed by adding a correction mass of 440 grams. The overall vibration level, after balancing, was measured to be within tolerable limit.
In normal steady state operation, the vibration level had gradually increased. The client suspected that the increase in vibration was due to wear out of balancing mass, which was kept at the inner side of the back plate in the rotor, during the last balancing activity in July 2021.
During visual inspection, it was observed that the balance mass kept in the last attempt had just worn out slightly. The existing mass was removed and It’s weighed as 386 grams. Hence, It was concluded that the vibration increase was not due to wear of the balancing mass, but due to uneven wear in the impeller.
In-situ dynamic balancing was once again carried out and a correction mass of around 730 grams was kept on the rotor.
In all the above three instances, the overall vibration level has been brought to acceptable limit as per ISO 10816.
Client has given positive feedback in LinkedIn.
