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We are operating 2 Frame 6 B machines with Mark VIe control system, with DLN-1 system, synchronized with grid in floating condition which is stable. The machine is continuously running on Preix steady state / low Nox condition. On continuous basis gas turbine is running on part load (approx. 24MW). Combustion hardwares were replaced with 32K compliant. Last MI was done in Feb 2015. The HRSG steam is used for process requirement.
Since last 3weeks we are finding the issue of flame intensity in secondary scanner No 5/6 attached to combustor 2/4. Low falme alarm is prevailing. CO in the exhaust was checked ad is 3 to 4 ppm.
No increase in vibration or other deterioration in performance observed.
Machine is due for MI in 2019. Machine was running for last 3 years with out any issue (Stopped only 3 times in 3 year).
Machine tripped yesterday on flame failure. 2 scanners were replaced and machine was re started without any notable change with out forcing any parameters. In normal operation when IGV is on temperature control mode and IBH is ON machine reaches TTRF 1080 deg C at 13 MW with IGV about 47 %. If IBH is OFF, rarely we go to lan lean positive and then to premix steady state.
Now with IBH off mode also reference temperature reaches 1080 with IGV in 56 % opening at 19 MW and goes to premix steady state.
When second time machine tripped on flame failure IGV calibration was checked, GCV/SRV/GSV calibration was checked, all were found OK. We started the machine and kept on low load at 12 MW due to process requirement to meet the steam demand.
Observations
Compressor discharge temperature CTDA1 / CT DA 2 difference were observed during starting. CTDA2 was 55 CTDA1 was 110 Deg C.
While scrutinizing the trip log in both trips minor variation in P2 pressure was observed and SRV also was found varying 20 minutes before the flame intensity variation occurs.
Based on this SRV/ GCV / GSV and IGV calibration was done.
Spread normally remains below the allowable range. Spread 1 touches the limit during the load increase
Current status
Machine run on lean lean positive (Before premix transfer state) at 17 MW in IBH close mode. Flame in all scanner healthy. Vibration 3mm/sec max.
Expecting valuable feed back and experiences in this line from the esteemed team. Can share the trip logs if required.
Since last 3weeks we are finding the issue of flame intensity in secondary scanner No 5/6 attached to combustor 2/4. Low falme alarm is prevailing. CO in the exhaust was checked ad is 3 to 4 ppm.
No increase in vibration or other deterioration in performance observed.
Machine is due for MI in 2019. Machine was running for last 3 years with out any issue (Stopped only 3 times in 3 year).
Machine tripped yesterday on flame failure. 2 scanners were replaced and machine was re started without any notable change with out forcing any parameters. In normal operation when IGV is on temperature control mode and IBH is ON machine reaches TTRF 1080 deg C at 13 MW with IGV about 47 %. If IBH is OFF, rarely we go to lan lean positive and then to premix steady state.
Now with IBH off mode also reference temperature reaches 1080 with IGV in 56 % opening at 19 MW and goes to premix steady state.
When second time machine tripped on flame failure IGV calibration was checked, GCV/SRV/GSV calibration was checked, all were found OK. We started the machine and kept on low load at 12 MW due to process requirement to meet the steam demand.
Observations
Compressor discharge temperature CTDA1 / CT DA 2 difference were observed during starting. CTDA2 was 55 CTDA1 was 110 Deg C.
While scrutinizing the trip log in both trips minor variation in P2 pressure was observed and SRV also was found varying 20 minutes before the flame intensity variation occurs.
Based on this SRV/ GCV / GSV and IGV calibration was done.
Spread normally remains below the allowable range. Spread 1 touches the limit during the load increase
Current status
Machine run on lean lean positive (Before premix transfer state) at 17 MW in IBH close mode. Flame in all scanner healthy. Vibration 3mm/sec max.
Expecting valuable feed back and experiences in this line from the esteemed team. Can share the trip logs if required.