Frame 7EA Combustion Alarm
Frame 7EA Combustion Alarm
(OP)
Hey all,
I'm having a problem with a GE Frame 7EA gas turbine. While running full speed no load, the exhaust spread becomes too large causing a "Combustion Alarm".
-We dissamebled the two cans that would, taking into account the exhaust twist, be in having issues. A loose secondary nozzle was found, the improperly installed gasket was replaced and the nozzle tightened.
-No smoke was noted coming out of the stack. I have included a trend of the last run that the alarm occoured in, it was at full speed no load.
-Everything seemed to be in a steady condition when suddenly the temperatures of 3 thermocouples drop causing the maximum differential to rise above the alarm limit.
-One of the thermocouples that contributed to the alarm also had an irregularity at the 6 minute mark on startup.
There is an attached powerpoint graph showing the trend from startup through shutdown (34.5 minutes).
Any ideas?
Thanks,
Carl
I'm having a problem with a GE Frame 7EA gas turbine. While running full speed no load, the exhaust spread becomes too large causing a "Combustion Alarm".
-We dissamebled the two cans that would, taking into account the exhaust twist, be in having issues. A loose secondary nozzle was found, the improperly installed gasket was replaced and the nozzle tightened.
-No smoke was noted coming out of the stack. I have included a trend of the last run that the alarm occoured in, it was at full speed no load.
-Everything seemed to be in a steady condition when suddenly the temperatures of 3 thermocouples drop causing the maximum differential to rise above the alarm limit.
-One of the thermocouples that contributed to the alarm also had an irregularity at the 6 minute mark on startup.
There is an attached powerpoint graph showing the trend from startup through shutdown (34.5 minutes).
Any ideas?
Thanks,
Carl





RE: Frame 7EA Combustion Alarm
1. Combustion hardware. Are the TC's adjacent in the exhaust stack?
2.Control system hardware. Look at the control drawing, could a single point failure, a card, a loose connection make this happen? Are all three TC's associated with the same control system hardware? Review the ambient compensation, a loose/ wrong ambient compensation throws off TC signals.
RE: Frame 7EA Combustion Alarm
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If we learn from our mistakes I'm getting a great education!
RE: Frame 7EA Combustion Alarm
I think that thermocouple you mentioned was telling you something significant during your acceleration run-up. One or more of the cans was in trouble all the way.
What did you observe at higher power levels with these same TC's on previous runs?
rmw
RE: Frame 7EA Combustion Alarm
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Frame 7EA Combustion Alarm
as you mention a "secondary nozzle" i understand you have a DLN 1 combustion system, otherwise you would not have such a nozzle.
as mentioned before if the three thermocouples are adjacent, then the problem is a can (most likely flaming out).
Have you checked exhaust emissions? an increase in CO will indicate poor combustion.
if one can is flaming out, perhaps the nozzles are not giving the correct pressure ratio.
give more info to troubleshoot.
saludos.
saludos.
a.