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Dear all experts,
For your information, our unit is 350MW single shaft GE9FA coupled with D10 Steam Turbine. Our current operation mode is peaking plant for supporting national grid. Currently, we are in the midst of annual outage for GT borescope inspection. Upon inspection, we had observed several failures at compressor casing, rotor blades and stator vanes.
Details of the defects observed as below:
- Rubbing and mushroom tip at upper halve compressor vanes from S1 to S17
- Rubbing and mushroom tip at upper halve compressor vanes from R1 to R17
- Rub tip condition at R1.
- Casing rub condition observed at upper halve side. From S4 to S17, rub area was observed around 10 to 2 o'clock position. Casing rub area was reduced around 11 to 1 o'clock position at S3 and S2.
However, there's no rub observed at S0 and R0.
According to GE, there are a few possibilities contributed to this phenomena. It might be due to increment numbers of hot start in operation, improper cooling in GT compartment and hot gas leak from GT horizontal joint. However, we found there's no burning sign in GT compartment and no gap at GT horizontal joint. The unit was put on cyclic operation since last year and having frequent hot starts. Nevertheless, there's no major findings observed during 2014 borescope inspection.
They had proposed for compressor blades/vanes blending to remove and reshape the mushroom tip. Blending works will be carried out in-situ by removing Compressor and CDC casing. Thus, the work only involves rotor blades and upper halve stator vanes due to insufficient outage duration for the work on the rotor removal. This decision is made, considering our major inspection scheduled in May / June 2016.
I would like to know if any of the users here have info or experienced with this failure before. What you had done to remedy the failure and have you discover the failure root cause? Any other recommendations given by GE to remedy the failure?
Thanks.
For your information, our unit is 350MW single shaft GE9FA coupled with D10 Steam Turbine. Our current operation mode is peaking plant for supporting national grid. Currently, we are in the midst of annual outage for GT borescope inspection. Upon inspection, we had observed several failures at compressor casing, rotor blades and stator vanes.
Details of the defects observed as below:
- Rubbing and mushroom tip at upper halve compressor vanes from S1 to S17
- Rubbing and mushroom tip at upper halve compressor vanes from R1 to R17
- Rub tip condition at R1.
- Casing rub condition observed at upper halve side. From S4 to S17, rub area was observed around 10 to 2 o'clock position. Casing rub area was reduced around 11 to 1 o'clock position at S3 and S2.
However, there's no rub observed at S0 and R0.
According to GE, there are a few possibilities contributed to this phenomena. It might be due to increment numbers of hot start in operation, improper cooling in GT compartment and hot gas leak from GT horizontal joint. However, we found there's no burning sign in GT compartment and no gap at GT horizontal joint. The unit was put on cyclic operation since last year and having frequent hot starts. Nevertheless, there's no major findings observed during 2014 borescope inspection.
They had proposed for compressor blades/vanes blending to remove and reshape the mushroom tip. Blending works will be carried out in-situ by removing Compressor and CDC casing. Thus, the work only involves rotor blades and upper halve stator vanes due to insufficient outage duration for the work on the rotor removal. This decision is made, considering our major inspection scheduled in May / June 2016.
I would like to know if any of the users here have info or experienced with this failure before. What you had done to remedy the failure and have you discover the failure root cause? Any other recommendations given by GE to remedy the failure?
Thanks.