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Hello Experts,
One of my gas turbines, a GE Frame 5, 25MW capacity with MK5 Control system suddenly tripped on exhaust over temperature trip. Prior to this trip the unit was running on 20MW with a maximum exhaust temperature of 498 degrees Celsius. It has been stable at this performance for over a year before the sudden trip on exhaust over temperature. Maximum operating temperature of the unit at base load is 501 degrees under ISO condition.
The trip was observed to be instantaneous with exhaust temperature spiking to as high as 800 degrees Celsius. There has been no history of exhaust over temperature on the unit and no surge of gas flow occurred before the trip. After the trip, the unit was restarted with but failed to accelerate beyond 70%TNH with exhaust spiking as high as 600 degrees Celsius. Also there was high emission of heat from load gear and turbine compartment melting the the plastic lighting fittings.
The following inspection and maintenance actions have been carried out so far to correct the issue:
-Replacement of all failed exhaust thermocouples
-Replacement of failed intervalve pressure transmitters
-Inspection and cleaning of fuel nozzles
-Cleaning of main air inlet filters which improved the CPD from an 1.2bar to 2.45bar at 70%TNH
-Calibration of gas control valves
-Calibration of IGV
-Boroscope inspection on hot gas section (no major defect was found)
-Inspection of exhaust thermal insulation
Following these inspections and maintenance actions, several startups were attempted but the unit failed to accelerate beyond 72% TNH with exhaust temperature getting as high as 600 degree Celsius.
Please I need to know what could be the possible cause of the high exhaust temperature and heat emission during startup, and what further actions we should take to correct it.
Thanks
One of my gas turbines, a GE Frame 5, 25MW capacity with MK5 Control system suddenly tripped on exhaust over temperature trip. Prior to this trip the unit was running on 20MW with a maximum exhaust temperature of 498 degrees Celsius. It has been stable at this performance for over a year before the sudden trip on exhaust over temperature. Maximum operating temperature of the unit at base load is 501 degrees under ISO condition.
The trip was observed to be instantaneous with exhaust temperature spiking to as high as 800 degrees Celsius. There has been no history of exhaust over temperature on the unit and no surge of gas flow occurred before the trip. After the trip, the unit was restarted with but failed to accelerate beyond 70%TNH with exhaust spiking as high as 600 degrees Celsius. Also there was high emission of heat from load gear and turbine compartment melting the the plastic lighting fittings.
The following inspection and maintenance actions have been carried out so far to correct the issue:
-Replacement of all failed exhaust thermocouples
-Replacement of failed intervalve pressure transmitters
-Inspection and cleaning of fuel nozzles
-Cleaning of main air inlet filters which improved the CPD from an 1.2bar to 2.45bar at 70%TNH
-Calibration of gas control valves
-Calibration of IGV
-Boroscope inspection on hot gas section (no major defect was found)
-Inspection of exhaust thermal insulation
Following these inspections and maintenance actions, several startups were attempted but the unit failed to accelerate beyond 72% TNH with exhaust temperature getting as high as 600 degree Celsius.
Please I need to know what could be the possible cause of the high exhaust temperature and heat emission during startup, and what further actions we should take to correct it.
Thanks