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Flame Failed After Crank Motor Cut Off
During starting up on gas, at 60% TNH after the cranking motor cut off the flame unstable and unit tripped on flame out.

Hi all,

Gas turbine: GE 9001E, 110MW

During starting up on gas, at 60% TNH after the cranking motor cut off the flame started to become very unstable and sometimes the unit tripped on flame out.

With regards to this problem, first we verify the flame detector (honeywell), carried the flame test for all 4 detectors, and all cable are tested. There were no findings. The intensity is good when we carried out the test. We also checked on the GCV by stroking. There is no abnormalities on the feedbacks by the lVDT. the FSG feedback is still same with the correspond opening in mm. All seems normal.

Yesterday, during starting up, we found out the turbine acceleration gradient is started to slow down from 47%TNH, before it fails at 60%TNH due to no flame. However the TMGV seems normal. The detail trending is as follows:

https://drive.google.com/open?id=0B_Y8r2_zrcTSdnJiVGlQaFQ4UHc

We still do not know the root cause. Is it due to torque converter vanes failure? Drain solenoid passing?

By control911 on 4 August, 2017 - 12:37 am

The workable link is here, disregard the previous one:

https://drive.google.com/file/d/0B_Y8r2_zrcTSdnJiVGlQaFQ4UHc/view?usp=sharing

1 out of 1 members thought this post was helpful...

Please post a graph of:

TTXM
TTRX
FSRT
FSRACC
TNHAR
TNHA
FLAME_INTENS_1
FLAME_INTENS_2
FLAME_INTENS_3
FLAME_INTENS_4
L4

(I don't know what the various flame sensor intensity signals are exactly for your machine, and if you would, please, make the pen widths of the machine with the problems a little thicker than the pen widths of the good machine--that would be VERY helpful.)

I would say--based on the limited information provided--that the problem is there is too little torque being provided by the torque converter/starting motor and the turbine control system is putting more fuel in to try to maintain the acceleration rate reference (TNHAR) and exhaust temperature control is limiting the fuel because the exhaust temperature is at the limit (TTXM=TTRX) and FSRT is taking control of the fuel from FSRACC (which should be controlling fuel during acceleration). And, when the torque assist from the starting means (torque converter/starting motor) drops off no more fuel can be added and flame is being lost.

We have no idea of how long the torque converter has been in service, nor how it has been maintained, nor how the guide vane angle indicator has been adjusted. It could be a leaking 20TU-1. It could be a clogged strainer upstream of the torque converter (we don't know what the oil quality is like). It could be a recent change in gas fuel supply quality. It could be the IGV LVDT calibration has recently been changed. It could be the turbine inlet air filters are very dirty. It could be the axial compressor is not very clean.

We don't know how long it's been since the last maintenance outage. We don't know what the ambient temperature is or how it's changed recently (if at all). We don't know if the unit exhausts to the atmosphere, or into a heat recovery steam generator (HRSG; "boiler"). We don't know if the unit is dual fuel (gas/liquid).

There's a LOT we don't know.

By Control911 on 7 August, 2017 - 12:39 am

Thanks CSA, sorry about the lack of informations. Will provide the details in the next graph.

>We have no idea of how long the torque converter has been in
>service, nor how it has been maintained,

The torque converter has been in operation for almost 20 years and has never been serviced. We maintain the torque converter for the rest of the units by swapping it with the good serviced unit. However this unit was never swapped at all. This GE 9001E basically used for peaking load despatch, which runs only upon request.

The IGV has been calibrated recently, so far there is no issue on the IGV.

Leaking 20TU-1 : We have pressure gauge monitoring at the torque converter and we have also compared it to the other unit during turn gear operation.

Last maintenance was done on Combustion inspection in last Aug 2016. Regarding the ambient temperature, it is about 30-32degC.
The unit is exhausts to atmosphere as it is the open cycle plant for peaking.

Thank you for the information.

It's probably about time for the torque converter to get exchanged like you've been doing with the other units. But, you should not rule out oil quality, torque converter strainer cleanliness, and 20TU-2 condition. You mentioned "turn gear", and I wonder if that's an actual turning gear mechanism, or the "slow-roll" which utilized the torque converter and 20TU-2?

Anyway, please write back when you have more information and any results from your troubleshooting efforts--successful or not--until you get resolution.