Vibration Diagnosis Approach for Industrial Gas Turbine and Failure Analysis

This study is carried out to analyze the problem of high vibration in gas turbine installed in power and desalination plant. This study is carried out in Al Ghubra Power and Desalination plant. Three case studies related to vibration problem were presented to diagnosis the cause of vibration and to find the root cause for failures that occur in the gas turbine.

The vibration data were collected using accelerometer at three directions for the rotational speed of 3000 rev/min at different load conditions. The date was presented in the form of graphs and comparative study was made. It has been observed in all the three cases, the high amplitude of vibration. Data were analyzed for this high vibration and corrective action initiated to rectify the problem to reduce vibration level. In the first case study the high vibration in the generator rotor side and is due to unbalance condition of rotor. The vibration level is reduced after performing balancing of rotor. In the second case study it is to find the reason for high vibration in the gas turbine during the first run up at Full Speed with No Load. It is observed that the high vibration in the generator is due to wear out parts and damage of pinion in the gear box. It is suggested to clean and replace the wear out part, and performed the same test again. It is interesting to note that the vibration level is minimal and it is within the acceptable level. In the third case, the flow back of gas to the machine casing resulting in accumulation of gas and when ignited caused the explosion in the exhaust side. Detailed analysis were made to analyze the problem and rectified.

In all the three case studies the investigation has shown that the high amplitude of vibration is due to many reasons hence it is suggested to implement a proper way of regular maintenance work to allow gas turbine to run smoothly without any problem. Few recommendations are proposed for preventing similar failures in the future. It is also suggested to use online condition monitoring tool to assess the operation condition and to decide the time of maintenance work.