High Exhaust Temperature Spread Trip

L

Thread Starter

LTW

Dear All,

Would like to share our recent experience and hope can get some advice/feedback from other users here.

Our unit is 9FA single-shaft combined cycle gas turbine, utilizing DLN 2.0+ combustion system. Type of control system is Mark V TMR, with HMI.

We encountered 2 incidents of unit trip due to High Exhaust Temperature Spread when deloading for overnight shutdown, during change-over firing mode from Premix to Piloted Premix.

From the trip log, prior to tripping, exhaust thermocouples #28 - #31 and #1 - #6 detected much lower temperature. From the SOE, no abnormality is observed for the GCVs. Only Flame Detector Trouble alarm and Combustion Trouble Alarm activated prior to High Exhaust Temperature Spread.

Problem occurs intermittently since 9th Oct 2012 and not every unit shutdown has got this problem, probably I can say 50% / 50%. Has anyone experienced similar problem before?
 
LTW,

What have you done to try to troubleshoot the problem?

What were the results of your efforts?

The Combustion Trouble alarm is telling you that a higher-than-allowable exhaust temperature spread (one of several different conditions) exists. Unfortunately, it only gives cognizant operators about nine seconds to take some kind of action (if possible) to lower the exhaust temperature spread before tripping the turbine.

Combined with a Flame Detector Trouble alarm, it's pretty clear from the information provided that diffusion flame has been lost in several combustors, or perhaps diffusion flame has not been established in several combustors.

Are you sure the IBH Control Valve and IGVs are working properly?

How long since the last maintenance outage (Combustion Inspection; Hot Gas Path Inspection; Major)?

Do you have gas fuel filters and/or a gas fuel strainer? Have you checked the filter and/or strainer drains for liquids and contaminants? Do the filter and/or strainer differential pressure gauges indicate a higher than normal differential pressure?

Is there a "knock-out" drum in the gas fuel supply piping to remove liquids? Have you checked the drain for type of liquid (hydrocarbon oils; etc.)? Many fuel nozzles can become plugged with oil/oil vapors entrained in gas fuel.

What is the dewpoint of the natural gas being burned in the unit? Is the gas heated for performance improvement, or for superheat protection?

Has there been a recent change in natural gas supplier or make-up?

Please write back with the answers to the above questions, and to let us know of the resolution.
 
Hi CSA,

Nothing much had been done on our side, except to stroke check the GCV 1, which was found to be in good working condition.

IBH Control Valve and IGVs are working properly, no alarm for these 2 equipments from the SOE during unit in normal operation.

Last Combustion Inspection was carried out somewhere in March 2012, and Major Inspection was performed in Jan 2010. Coming HGPI will be early of next year.

We do have a gas fuel strainer and its dP reading is within the normal operating limit and no dP high alarm detected.

Not sure on the fuel gas dewpoint, but we can say there is not much changes in the gas composition and it has been quite consistent all these while. Our performance gas heater is mainly for Gas Turbine performance, by pre-heat the fuel gas before entering combustion chamber.

Would like to add one more thing here. Unit does not encounter any problem during start-up and problem only occur during shutting down.

Thanks to all for the advice/feedback given!
 
We experienced HIGH EXHAUST TEMPERATURE SPREAD TRIP due to the fault in IBH trip solenoid. Our system is GE 9FA and control system is MARK VIe and GT capacity is 230 MW .

Trip Log alarm >>
1.30 Am IBH control valve suddenly open >> on that time IGV angle is greater than 62 DGA and load was higher than 190 MW
1.35 AM IBH manual isolation was closed and IGV angle and load was also high
</b In between 1.30 AM to 11.30 AM <IGV angle was more than 62 DGA and load was high \b >

>>9.30 AM we replaced IBH trip solenoid l20th1x/20TH-1 IBH trip solenoid. It became malfunction. So we replaced it with new one.

</b Between that time during maintenance we forcing the l20th1x solenoid to true, note: its default set was False b\> one that time IGV > 62 DGA

>>10.00 AM Replaced the IBH trip solenoid
</b In between 1.30 AM to 11.30 AM <IGV angle was more than 62 DGA and load was high \b >

>> 9AM to 10 AM IBH trip solenoid maintenance
>> 11.39.40 Combustion trouble alarm annunciated
>> 11.39.45 High exhaust spread temperature trip annunciated
and GT trip
no flame detector alarm or other fault identified. Thermocouple, liner and transition piece all are ok. No other abnormalites identified.

// The trip solenoid of IBH rectified in 10 AM after 1.38 Hour>> 11.39 AM the trip incident happened. //
During trip time IGV angle was less than 59 DGA and load was low >> in this condition IBH should starting to open but IBH was closed>> GT trip

What might be the true reason for this incident.
 
Hi

I Strongly suggest you to get /catch the trends views/alarms trips logs.. from the control system about this event ...and post them here ..so we can support you by a better way..

Is that a simple/combined cycle...

Did you restart unit after that event ...

James
 
Did you perform IBH valve test as per MARKVIE app code...

Is there any IBHFault ...detection ..displayed

You should see L3BH SENS ALARM MESSAGE DISPLAYED in case of sensor fault is that the case here..
 
You better check IBH position detection in this case...

Look on the isntalled app code there is a sequence /block diagram for IBH Control valve position test /slew rate test..
 
I am waiting for CSA and other experts' judgment. This HIGH EXHAUST SPREAD TRIP topic is very popular on control.com. There are many contents but I can not find related to. The threads LTW posted >> TRIP's possible causes are discussed by CSA. To relate with this I post here directly so that those who may study can also relate to this. In my case, HIGH exhaust spread trip due to the fault in IBH but how it happened, I am unsure about it. I think I should repost it in a new thread.
 
I am waiting for CSA and other experts' judgment. This HIGH EXHAUST SPREAD TRIP topic is very popular on control.com. There are many contents but I can not find related to. The threads LTW posted >> TRIP's possible causes are discussed by CSA. To relate with this I post here directly so that those who may study can also relate to this. In my case, HIGH exhaust spread trip due to the fault in IBH but how it happened, I am unsure about it. I think I should repost it in a new thread.
All the best with this issue!
 
CSA is traveling, and ControlsGuy25 has MUCH more knowledge and experience with GE Belfort equipment and systems and--most importantly--their "programming" than I do. Running with alarms is, ..., well, ..., not a really great idea--especially if nothing was done to try to resolve the alarm(s) during running and hope was being used to continue operation (hope that nothing would be damaged, or nothing would trip, etc.).

The thing I an unclear on is after the re-start did the same thing happen again??? Please provide a better timeline of the events, including alarm time-stamps, and what was done to try to resolve the problem--INCLUDING the results!!! You say the IBAH was tested--HOW was it tested? WHAT were the results? WHO decided it was working? WHAT steps were performed during the testing, and WHAT were the results?

ControlsGuy25 (James) has this now.
 
Looks like Original Poster decide to open a thead on another forum for this issue...

All the best with this issue..

We tried to support but your reacted as negliging my advises....

Was ready to assist from here but sometimes it is better like that i recognize..


No problem

Hasta luego
 
No reply from Abby is not a good sign of consideration/respect ...Original poster was waiting from CSA comments but he did not provide enough informations dats on the issue..

I posted few questions and after seen that i was right ...he just told me that he waiting answer from other experts

Okay let me tell you that We and I supported many people from here with best solutions..And we worked in the field more thna you can imagine ...across 25 countries and 35 projects..
And now you come like okay let me wait from this or that guy...I saw many times that scenario in the field ..just to tell you that you not talking to beginners guys ...here..
...

I know GEEPE and their solutions better than you can imagine ...actually i did my studies and live 10 km from GEEPE...

Do not take it personnal it is just to remind sometime that we are here to share/learn !
 
Actually, you do seem to take it VERY personally, James. But, I can kind of understand why.

I have re-read Abby's posts a couple of times and I think he's just trying to understand what could have caused the spread trip. If he had provided the Trip Display or Historical Displays (from Trender) we could probably have been more precise--but it seems the unit was unloading and the IBH system was not in service--for whatever reason (it seems that at some point--for SOME STRANGE reason) the manual IBH isolation was closed and it may still have been during unloading--and when the air flows got high enough there was probably some lean-lean blowout or something similar which occurred due to the higher than normal air flows through the compressor at low loads.

That's all I will offer on this--even if Abby comes back. His posts were very difficult to read and understand (it seems he was trying to add emphasis to poor grammar with the bracketed codes, and didn't know what he was doing or how to do it) and his
"timeline" was just all over the place. If he reads this response I hope he learns from it--a logical timeline is extremely helpful if the Trends and Alarm History files can't be provided.

AND, without better data and with what we were given to work with by Abby, not much more can be said.

I would be curious as to which "other forum" Abby has posted to.... But, it's not critical.

We are providing a free service--most people are going to treat it that way and do as little as possible to close the loop and provide feedback--which is their prerogative and while it may not be polite or proper, it's their prerogative--and we can remember that in the future.

Grow some duck feathers, James--and let this stuff just roll off your back. You're going to contribute to your anxieties if you don't learn to let this go. (And, trying to shame people isn't really going to do much more than deter others from writing at all, and maybe even not follow this forum or you in the future.)

Hasta pronto.
 
James, I am extremely sorry if I hurt you. My grandmother died a few days earlier. Also, I faced some issues about my mental health therefore I was disconnected.
I see several threats of yours, I learnt a lot from this. I am very grateful to you, you are my admiration.

About waiting for others expert judgement as I said earlier, it included you and others. Please do not mind, I am sorry!!! Please accept my apology.

Thank you for all your support !!!
 
James, I am extremely sorry if I hurt you. My grandmother died a few days earlier. Also, I faced some issues about my mental health therefore I was disconnected.
I see several threats of yours, I learnt a lot from this. I am very grateful to you, you are my admiration.

About waiting for others expert judgement as I said earlier, it included you and others. Please do not mind, I am sorry!!! Please accept my apology.

Thank you for all your support !!!
Abby,

So sorry to hear that...
I also have my mother in bad health..

My condoleances ances and apologies.. If I hurted you.. It was not the target...
Just a remind for people here... To try to respond as best as they can..

I will pray for you to recover you health..

And thank you for sweet words/comments..I really appreciate..
Keep blessed...
Any time!
James.
 
By the way looks like you are from Bengladesh...
I know the country.. As I worked there on a plant..
Which plant is yours..
I know Mymensigh (6B), Tongi(9e)..
Siddirgan.(9fa).. And now there is 9H in Mednaghat...

Cheers
James
 
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