GE Frame 9E First Fire and Maintenance

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Hi

I am working as an operation engineer in Najybia power plant start-up team. We have four GE frame 9E dual fuel 125 MW gas turbines. We plan to first fire a unit in two weeks. I want to learn that how long before the unit put into TG rpm?

After TG period completed, unit will start in CRANK mode. Is there any test in CRANK mode? Does unit need to do WW before fire start?

If anyone has GE manual about this progress, can share us?
 
Hello,

If you're re-starting a unit after a maintenance outage, that's technically not a "first fire" event. First fire refers to the first time a gas turbine is ever started during installation/commissioning. There are a LOT of tests to do prior to and during first fire, some of which are appropriate after a maintenance outage, but some of which are not.

Operation on turning gear for approximately 8 hours is usually recommended prior to starting a gas turbine after a maintenance outage where the rotor has been removed and/or has been stationary (at zero speed) for several weeks. (Rotation for removal/installation of turbine buckets and tightening coupling bolts doesn't count.)

What you want to test after a maintenance outage, particularly a large-scale maintenance outage (which I personally classify as a HGPI or a Major) is that lube oil is flowing to all bearings, that the unit will go on turning gear (cooldown) without any problems from zero speed, that the unit will go on CRANK without any problems, that vibrations while on CRANK are not excessive, and that the unit will go back on cooldown after rotation. (Some newer units won't automatically put the unit on cooldown after being above zero speed unless flame was detected; this logic to enable cooldown operation after flame was detected can easily be forced to ensure the unit will automatically go on cooldown once it reaches or gets near zero speed (depending on the type of cooldown mechanism/turning gear provided/used with the turbine).

Depending on the type of fuel being burned, it's advisable to do a false fire (put the unit if FIRE mode with the spark plugs/ignitors disabled) to fill the fuel lines to the combustors. This is also a go/no go test for fuel leaks (it shows major fuel leaks pretty quickly, especially for liquid fuel systems). And this false fire (some people falsely call it a "dry fire") test also confirms the fuel control system's ability to limit fuel flow during starting after fuel valves may have been removed/refurbished/replaced. But, it's most useful for filling fuel lines--particularly liquid fuel lines. I occasionally "force" the firing timer to extend it to 60-90 seconds to allow sufficient time for leak checks and to fill the fuel lines, then returning the timer back to its normal value before enabling the spark plugs.

As for water washing, well, it's quite often done before a maintenance outage, but if not then it's usually done after a maintenance outage before re-starting just to clean the axial compressor as best as possible. It's not always done, either--but this is as good a time as any if one was not done before the start of the outage to do one, since the unit is already down and cool.

As for manuals/procedures from the OEM/packager, good luck with that. There's very little written by the OEM--or followed--by commissioning or plant personnel, and what is written and followed is selectively followed and modified as felt necessary by the individual performing the activity.

As long as you use good judgement and take into account the possible problems which might occur after an outage based on the work done during the outage then you will be safe.

Anyway, that should about cover it. If you have any other questions, we're here to try to answer those questions.

Hope this helps!
 
Thanks a lot for your assistance. We have four turbine, and construction is very close to completed. We will give first fire to one unit.

In fact I have added one more question. How I can calculate unit HGPI and MI hours? Our turbines can run with fuel gas, LDO or HFO. Unit will run mostly with HFO and water injection system will be in service. My previous plant was ENKA Gebze Combined Cycle PP in Turkey and we were operating GE 9FA and they were running just fuel gas. I have not experience liquid fuel turbines unfortunately. To reach the necessary documents very difficult in Iraq. Your comments is very important for me.

Thanks a lot again
 
>https://powergen.gepower.com/conten...obal/en_US/documents/technical/3620M_0215.pdf

Thanks for your assistance. I have found this document from internet before. I calculated the maintenance period for different fuel. I wanted to confirm my calculation, because maintenance period seemed me very short.

Fuel Gas

1 year = 8760 hours

Maintenance Interval = 24000 / Maintenance Factor

Maintenance Factor = Factored Hours / Actual Hours

Maintenance Factor = (1)*(8760+0+0+0)/(8760) = 1

Max Maintenance Interval for Fuel gas = 24000 / 1 = 24000 hours

LDO

1 year = 8760 hours

Maintenancve Interval = 24000 / Maintenance Factor

Maintenance Factor = Factored Hours / Actual Hours

Maintenance Factor = (1,9)*(0+(1,5*8760)+0+0) /8760 =2,85

Max Maintenance Interval for LDO = 24000 / 2,85 = 8421 hours

HFO

1 year = 8760 hours

Maintenance Interval = 24000 / Maintenance Factor

Maintenance Factor = Factored Hours / Actual Hours

Maintenance Factor = (1,9)*(0+0+(2*8760)+0) / 8760 = 3,8

Max Maintenance Interval for HFO = 24000 / 3,8 = 6315 hours

For HFO 6315 hours means 263 days. Approximately each 9 months, unit needs HGPI. I think this period is very short. In addition manual says if vanadium addition system is in service, turbine wash should be performed every 250 hours. As well, HFO should be treated by demulsifier system. I can not understand how HFO operation has lower operation cost.
 
If you've followed the instructions in the manual, then you have calculated correctly. I see you've learned the "dirty little secret" about HFO (Heavy Fuel Oil; "bunker"; residual fuel oil; etc.). It might be cheaper from a fuel price perspective, but it's not very good for the turbine and auxiliaries and so the intervals between maintenance outages are usually shorter than for other fuels. Which means parts need to be ordered more frequently, and the machine must be taken down more frequently--all of which adds to the overall cost when operating with a less expensive fuel.....

It's not what everyone expects, but, it seems like someone didn't do their homework when choosing this fuel and expecting it to be "cheaper" in the long run. It may be less expensive over decades as opposed to LDO (Light Distillate Oil; "diesel"; distillate fuel), but it still requires more maintenance outages/parts than other fuels--even LDO. It's just not a great fuel; it can be corrosive, it has heavy metals which even with the best emulsifiers can still plate out on the turbine nozzles/buckets; it is erosive (to fuel nozzles and liquid fuel flow dividers and high pressure liquid fuel pumps--more so than LDO). Not to mention, it usually requires heating to make it flow and easier to atomize, and sometimes it requires other treatments as well (separators or centrifuges).
 
Hello everyone!

Sorry, if I step in the conversation, actually we are experiencing HGPI in our plant for one machine and other will start in few weeks. I want to ask about the Pre-Start checks (as being Control engineer) that we must perform before going for start-up after completion of HGPI. We don't have any major activity regarding control system during this maintenance activity. Just for protection we have removed some cabling from marshaling and the instruments from turbine hall which is a normal routine.

During this maintenance activity, we are just checking all the junction Boxes for cabling tightness and other activities according to PM schedule. My point here is what different type of test we must perform before start-up. Like if I can list few of them; Spark plug testing, Compressor Bleed Valve Solenoid, etc. Ours machine is FRAME-9E, Open cycle and main (Operating) fuel is Crude Oil.

Thank you,
 
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