The customer is a leading cement manufacturer in Saudi Arabia and the Gulf Region that always strives to expand its product diversity. To enter the Jordanian market he made a big investment of 400 million dollars in 2007 to build up a new cement plant there. This plant was expected to start operation in the second quarter of 2010 with a production capacity of 5,000 tons daily.
Vibration Troubleshooting Ensures Reliable Raw Mill Fan’s Operation
The cement plant’s raw mill fan circulates gas which supports the production process and is driven by a 2.8 MW motor. During the plant comissioning phase the customer made a performance test of the raw mill fan. Extremely high fan vibrations – that even exceeded the maximum set value in the protection system – became obvious. The fan tripped several times. Due to this result the fan could not be commissioned and the customer suspected unbalance as reason. Thus, he looked for a third party that could provide an accurate diagnosis and a solution for the problem.
These investigations revealed that the high vibration values could be traced back to loosen bolts of the fan pedestal and an excessive foundation flexibility. The conclusions were summed up in an analysis report including clear instructions. Following these reommendations the cement producer thightened the holding down bolts of the bearing pedestal and increased the pedestal foundation by 110 tons. Finally, to reduce the fan‘s vibration, balancing was done using the FAG Detector III Balanding Kit. Thanks to these measures the vibrations decreased from 42 mm/s to 4.5 mm/s when the fan operated with closed dampers and an operating temperature of 74 °C. But when the customer and Schaeffler made another test with open dampers the vibrations of the fan increased exponentially within a few minutes and the fan started tripping again. A detailed analysis of the vibration data showed that this failure based on a problem in the duct system. The customer fixed this and since then the fan is operating in normal condition.
