Turbine Blade Adjustment For Performance Recovery

Abstract

The issue of sudden vibration disturbance occurred at the Power Plant during full load operation. An investigation was conducted by reviewing the trends in the Distributed Control System and performing a startup trial using vibration monitoring equipment. Based on the analysis, the vibration was identified to be caused by rotor unbalance. However, during the balancing process, it was found that a 1300-gram balance weight was required. With a mass weight like that, it is not possible to continue the balancing process, therefore, a deeper investigation was undertaken by opening the upper casing to determine the root cause of the issue. Upon opening the upper casing, a broken turbine blade was found at stage #5 on the generator side. As there were no spare blades available at the Dieng Geothermal Power Plant, a corrective action was required. It was decided to cut the turbine blade at stage #5 using a plasma cutting method. With this method, the highest vibration level observed remained below the maximum allowable standard. Considering that the procurement of a new blade would take approximately one year, the blades cutting for turbine vibration recovery as a solution to expedite the repair process to approximately less than 2 months. This approach allows the power plant to continue supplying electricity to meet public demand and enables the company to maintain economic gains, rather than facing a total shutdown while waiting for the new blades.