Hello Control Community

We had a problem with our frame 6 ms6001 GT controlled with GE Mark 5 TMR
The problem has begin last week the GT wasn't able to fire up. no work has being done on the GT
FQL1 at 3% at 20FL openning pressure is at 5 bars
The 3 77FD's looks identical
We check the 2 spark plugs they works fine
we check the nozzles of the chambres 1 & 10 they work fine
Check valves of the 10 nozzles works fine
we suspect the booster and we changed; same result ignition failed
we put an external source of air we had ignition once we tried again same way we had same problem
any suggetion please

 

@Zaam10,

You seem to have done all the usual things during troubleshooting--and thank you for providing details of the results of the troubleshooting!--and identified a potential issue: The Booster Atomizing Air flow/system. If this is a dual fuel machine (distillate/natural gas) there are usually one or two check valves in the Atomizing Air system to prevent blackflow during starting and possibly during off-line water washing; have you checked the Atomizing Air P&ID to see if the Atomizing Air system has any check valves which may be not functioning correctly?

Usually, problems with starting on liquid fuel are: 1) insufficient or unstable liquid fuel supply pressure to the machine; 2) air trapped in the liquid fuel supply piping and/or liquid fuel filter vessel(s) (indicated by wildly fluctuating Liquid Fuel Flow Divider speed pickups--which you seem to have eliminated); 3) failing liquid fuel check valves (which you appear to have eliminated); 4) failed or failing liquid fuel purge system check valves (these are typically only present on a dual fuel machine).

Are you certain the liquid fuel suction strainer between the liquid fuel storage tank(s) and any liquid fuel forwarding pump is clean? Have you physically checked the liquid fuel filters to be sure they aren't clogged/dirty? Does the liquid fuel flow-rate (FQL1) match the liquid fuel flow-rate reference (usually signal name FQR) during firing?

Does the machine have an induction electric motor starting means, or a diesel engine starting means? Does the machine speed appear to be normal during the firing attempts (indicating a properly functioning torque converter for an induction electric motor starting means, and a properly functionling diesel governor for a diesel starting means)?

Was there a trip before the machine needed to be re-started, or was the prior shutdown a normal, operator-initiated shutdown? If the machine was tripped, what was the cause of the trip?

What were the exhaust temperature spreads prior to the trip/shutdown when the machine was at rated speed and some load--normal or excessive?

I'm presuming the Booster Atomizing Air Compressor is induction electric motor driven; but older machines had different means of driving the Booster Atomizing Air Compressor. If it's electric motor driven is it directly coupled to the Atomizing Air Compressor or are there rubber belts and pullies coupling the electric motor to the Atomizing Air Booster compressor--and are they properly tightened?

Most Atomizing Air Booster Compressors are high flow/low pressure positive displacement compressors, which, unfortunately makes checking the pressure difficult to impossible by just looking at the Atomizing Air Pressure gauge (because the discharge pressure of the Atomizing Air Booster Compressor is very low compared to the normal Atomizing Air Compressor discharge pressure so it barely registers on the main gauge). Also, it's unusual for GE to provide a minimum Atomizing Air Pressure required for firing.... You say you've replaced the Atomizing Air Booster compressor; with a new or refurbished or used compressor?

There are some types of liquid fuel nozzle assemblies that have been known to have internals that loosen during operation (due to vibration and thermal cycling during starting/stopping).

That's about all I can suggest. It would appear you have identified low Atomizing Air Booster Compressor flow/pressure as the source of the problem, so what remains is to identify the cause for the low flow/pressure. I have seen some atomizing air tips on fuel nozzles that were worn/eroded that cause problems during starting--but also often resulted in higher than normal exhaust temperature spreads during operation.

Finally, if the machine tripped while running at load prior to the failed start attempts it could be that there are hardened liquid fuel "bits" blocking the tips of the liquid fuel nozzles, or dribbling into the atomizing air tips of the nozzle assemblies, because they weren't properly purged from the fuel nozzles and/or atomizing air tips of the nozzle assembly. And, while the problem could be low atomizing air pressure/flow during starting there might also be some liquid fuel flow restrictions either in the supply system or the liquid fuel filters/vessels.

I hope this helps. Please let us know what you find and how you resolve the issue!