F6- 6581b - Maintenance interval calculation

Hello everybody.
I just found a document about how to calculate "Maintenance Factor" which mentions:

1.png
My questions are about the parameters:
NA = Annual number of part load start/stop cycles (<60% load)
1)Is this mean that if the operator starts the GT and reaches 60% load this counter will increase by 1?
2) If the answer to the first question is yes, What happens to this counter if the operator starts the GT and reaches 60% load and after 10 min selects base load? I mean this is not a start for a 60% load so what happens to this counter?
3) what does Start/Stop means in this definition? is it mean that if the operator stops the GT from 60% load this counter increases by 1?

NB = Annual number of base load start/stop cycles
1) is this means if operator starts the GT and reach to base load this counter increases by 1?
2) If the answer to the fisrt question is yes, what happen to this counter if operator in same start operate the GT for more that 2 days (for instance) in part load and after that select base load? is this base load start or part load start? what haspped to this counter?
3) what does Start/Stop means in this definition? is it mean that if the operator stops the GT from base load load this counter increases by 1?

NP = Annual number of peak load start/stop cycles
1) is this means if operator starts the GT and reach to peak load this counter increases by 1?
2) If the answer to the fisrt question is yes, what happen to this counter if operator in same start operate the GT for more that 2 days (for instance) in part load and after that select peak load? is this peak load start or part load start or base load strart ( because unit has to pass to base load first and after that reach to the peak load. base load start/stop counter increases by 1 during reach to peak load?)

E = Annual number of Emergency start
1) Is "Emergency start" means that start GT to base load in 5 min (I read this from a GE discription that Im not sure about it)?
2) is the rate of "Emergency start" means TNKR1_6 = 8%/min ?
3) what is logic of L83JD6 for this ? we dont have L83JD6 in our logic. can anyone make a example for this logic ( L83JD6) ?


thank you in advance for your attention and help.
 
In my personal opinion, you are overthinking this. For example, unless you routinely start your Frame 6B (equipped with DLN-I combustors AND IBH (Inlet Bleed Heat)) and run it up to 60% load, wait for 30-60 minutes, then load it up to Base Load, then perhaps you should think about recording that as a Base Load start. Otherwise, if you do this once every three weeks (start and load to 60% and then load to Base), you're fine. AND, since your unit is operating in Premix Combustion Mode (because IBH is active), the unit is operating in the mode it should be operating in.

If, on the other hand your unit has DLN-I combustors but does not have IBH, and you regularly start and load to 60%, stop and hold for 30-60 minutes, then continue loading to Base Load (and Premix Steady State)--then you would have to think about whether these are "part-load" starts or Base Load starts. Because, without IBH active at 60% load you are going to be in Lean-Lean Combustion mode, which isn't really the combustion mode the machine is designed to operate in. The temperatures in BOTH the primary and secondary combustion zones are higher than normal (because of the fuel splits in diffusion flame mode) and so the wear on the combustion liners will be higher while operating in extended periods in Lean-Lean Combustion mode.

We would have to examine the programming in the turbine control system to see precisely how the timers and counters are programmed to record part load starts and Base Load starts--and we can't do that remotely.

These charts are NOT cast in concrete. They are meant to be guidelines to be used to determine when to perform maintenance outages (which are frequently put off for some reason or other (usually cost, often production)). And, honestly, they are intentionally complicated for the average person to decipher--so that one might call the OEM for help with determining when to schedule the next maintenance outage.

Seriously, these are guidelines that should be used to create your own maintenance intervals. And, only YOU can know how your machine is operated day in and day out, week to week, month to month, year to year. Does the machine experience a "lot" of trips? Or not many? Does it start once or twice a month, or once or twice a day five days a week? It's the thermal stresses experienced during starting and tripping that are the hardest on the machine and its internals. AND, how it's operated on load--that 60% load business: Are you doing that regularly, or infrequently--AND does the machine have DLN-I AND IBH or DLN-I and no INH, or conventional combustors (in which case you can just forget about this nonsense altogether)? There are a LOT of factors which aren't really properly covered in these GE publications--which attempt to try to cover just about EVERY Frame size in EVERY publication, "one size fits all"--when one size DOES NOT really fit all.

Take a chill pill, think about your machine and how it's configured, if you have someone at site who can look at the timers and counters programming and answer some questions for you that would be very helpful, too. Think about how the machine is operated, how often it trips, how often it starts, how often it fails to start (because those can be hard on a machine if flame is establish in only a few combustors and it trips during acceleration), they type(s) of fuel(s), how often off-line water washing is performed, etc. Are the inlet filters changed when needed? Is the inlet air clean of hydrocarbons or dust (cement dust; road dust) or machinery exhaust (diesel engines; train engines), is the unit sited near the ocean (salt air), is it foggy, etc., etc. All of these things should be taken into account when planning maintenance outages. Maybe the last 10-1/2 months the unit has been started almost every day, when normally it starts six or seven times in that same period. Or vice versa. Things change, and that should be considered, too.

But, as much as we want some hard and fast guidelines to follow to make our lives easier--there's just too many variables which should be--must be--considered when planning maintenance outages. Cost and lost production are two VERY important factors, too.

Lastly, the OEM has a LOT of long-term service agreements where they tell the plant when the next maintenance outage will be. They have devised this complicated routine as a way of extending the time between outages--to the OEM's benefit!--so they can reduce the number of outages while still getting paid premium dollar for service and support. And they use this "guideline" as their basis for their "recommendations" for maintenance outage planning. Because it's so confusing, they can interpret however they please--and the way that pleases them the most is to put off maintenance outages as long as possible to make as much money as possible. (A lot of these contracts include a suggested number of maintenance outages (meaning the contract proposal was based on x number of maintenance outages), so if they can reduce the number maintenance outages to less than the number used in the proposal any way they can, they can keep more money. It's as simple as that.)

Again, without being able to see the program running in the turbine control at your site and without knowing anything more than it's a GE-design Frame 6B heavy duty gas turbine (without knowing the combustion system and the auxiliary configuration and the fuel(s) being burned) there's not much more we can tell you. Other than these are guidelines, probably for DLN-I combustor-equipped machines. The publication you copied this from may have more information--or it may not. But, these are still guidelines, and are subject to interpretation and analysis and adaptation.
 
Hello everybody.
I just found a document about how to calculate "Maintenance Factor" which mentions:

View attachment 2478
My questions are about the parameters:
NA = Annual number of part load start/stop cycles (<60% load)
1)Is this mean that if the operator starts the GT and reaches 60% load this counter will increase by 1?
2) If the answer to the first question is yes, What happens to this counter if the operator starts the GT and reaches 60% load and after 10 min selects base load? I mean this is not a start for a 60% load so what happens to this counter?
3) what does Start/Stop means in this definition? is it mean that if the operator stops the GT from 60% load this counter increases by 1?

NB = Annual number of base load start/stop cycles
1) is this means if operator starts the GT and reach to base load this counter increases by 1?
2) If the answer to the fisrt question is yes, what happen to this counter if operator in same start operate the GT for more that 2 days (for instance) in part load and after that select base load? is this base load start or part load start? what haspped to this counter?
3) what does Start/Stop means in this definition? is it mean that if the operator stops the GT from base load load this counter increases by 1?

NP = Annual number of peak load start/stop cycles
1) is this means if operator starts the GT and reach to peak load this counter increases by 1?
2) If the answer to the fisrt question is yes, what happen to this counter if operator in same start operate the GT for more that 2 days (for instance) in part load and after that select peak load? is this peak load start or part load start or base load strart ( because unit has to pass to base load first and after that reach to the peak load. base load start/stop counter increases by 1 during reach to peak load?)

E = Annual number of Emergency start
1) Is "Emergency start" means that start GT to base load in 5 min (I read this from a GE discription that Im not sure about it)?
2) is the rate of "Emergency start" means TNKR1_6 = 8%/min ?
3) what is logic of L83JD6 for this ? we dont have L83JD6 in our logic. can anyone make a example for this logic ( L83JD6) ?


thank you in advance for your attention and help.
Humm I know why you get stucked ..

There are differents calculation modes on "Maintenance Interval"

The document that you shared here is for HGPI maintenance interval

There is also a calculation but on a different approach for CI maintenance interval

And one must know that there is"HOURS BASED" & "STARTS BASED" which are completely differents calculation modes..

Also the document that i have read (For Hours based ) take in account other parameters like 'Load severity /fuel severity"...

You will also have estimated ( by GE ) Repairs and replacement interval tab..

GE uses his own methods to give you an idea on when to repairs or replace parts after getting that Hours/starts based calculations results...


For example on a frame 6B :

Combustion Liner should be repair at 1*CI ( which is Calculation on CI maintenance interval ) and replaced at 4*CI ( for non DLN)
AND from 4*CI to 5*CI for DLN units

Cheers,
James
 
You asking following questions:

3) what is logic of L83JD6 for this ? we dont have L83JD6 in our logic. can anyone make a example for this logic ( L83JD6) ?

Note that L83JD6 signal name called "Load Fast Rate"
 
We would have to examine the programming in the turbine control system to see precisely how the timers and counters are programmed to record part load starts and Base Load starts--and we can't do that remotely.

Dear WTF,
First of all, thank you for your answer and your spending time answering this question.

here are my answers:

In my personal opinion, you are overthinking this. For example, unless you routinely start your Frame 6B (equipped with DLN-I combustors AND IBH (Inlet Bleed Heat)) and run it up to 60% load, wait for 30-60 minutes, then load it up to Base Load, then perhaps you should think about recording that as a Base Load start
I want to implement logic to calculate maintenance interval automatically. Because of this I need clear and straight explanation.

We would have to examine the programming in the turbine control system to see precisely how the timers and counters are programmed to record part load starts and Base Load starts--and we can't do that remotely.
I checked out the logic for any counter/timer for OH (operation hours) or EOH (equivalent operation hours). There is only one "totalizer" in which:

As you can see there are common or general counters and timers. There is no counter for the number of starts/stops which is the main reason for asking this question here. I want to implement the logic for maintenance factors in our units based on the related document.



These charts are NOT cast in concrete. They are meant to be guidelines to be used to determine when to perform maintenance outages (which are frequently put off for some reason or other (usually cost, often production)). And, honestly, they are intentionally complicated for the average person to decipher--so that one might call the OEM for help with determining when to schedule the next maintenance outage.
I totally do agree with you ;)
 

Attachments

Humm I know why you get stucked ..

There are differents calculation modes on "Maintenance Interval"

The document that you shared here is for HGPI maintenance interval

There is also a calculation but on a different approach for CI maintenance interval

And one must know that there is"HOURS BASED" & "STARTS BASED" which are completely differents calculation modes..

Also the document that i have read (For Hours based ) take in account other parameters like 'Load severity /fuel severity"...

You will also have estimated ( by GE ) Repairs and replacement interval tab..

GE uses his own methods to give you an idea on when to repairs or replace parts after getting that Hours/starts based calculations results...


For example on a frame 6B :

Combustion Liner should be repair at 1*CI ( which is Calculation on CI maintenance interval ) and replaced at 4*CI ( for non DLN)
AND from 4*CI to 5*CI for DLN units

Cheers,
James
Dear ControlsGuy25,

Thanks for your answer. yes there is a time base calculation and you probably mean this:
asd.png

as I mentioned in the previews replay I want to implement the logic for both time base and start base calculation.
 
A quick update would be appreciated
I think my questions are clear and I need more details. The last update is I am gathering information and I want to write descriptions for each Item and based on them start writ specific logic for this purpose and after that show the counters and related alarms for the operator.

I guess the experiences of different operators could be helpful to make the logic more accurate.
If I find something new I'll share them with you.
 
Dear ControlsGuy25,

Thanks for your answer. yes there is a time base calculation and you probably mean this:
View attachment 2483

as I mentioned in the previews replay I want to implement the logic for both time base and start base calculation.
Dear @no_bug,

Yes I was referring for this calculation mode for HGPI and also one for CI..

I Will review the app code that I got here there, see if kind of totalizer /function block available and will be back to the thread.

Cheers,
James.
 
I found some datas/informations on a app code for Frame6B and also for Frame9FA

The thing is that totalizer function block ( frame 9FA) is too big and get displayed on 2 differents pages and some signal names are not well displayed..

Otherwise the Totalizer fucntion block for frame 6B is ok but do not have lot informations like the one on Frame9FA
1666437973724.png
 
On the App code for Frame 9FA there is kind of manual initiated start counter logic ..do you have that function available ( i guess so, since that GEEPE implemented it on their units)

1666438302750.png
 
You will need to compare first what is in the app code that you got at site and tehn try to add/modify some logic from other good examples on Totalizer /counter ( Hours /starts Factored) then as you wrote display messages/alarms for the operators..
 
You will need to compare first what is in the app code that you got at site and tehn try to add/modify some logic from other good examples on Totalizer /counter ( Hours /starts Factored) then as you wrote display messages/alarms for the operators..
First of all, thank you for your answer.
We have the same totalizer in our (F6B - Mark VIe) logic. I compare each pin of your totalizer with ours. of course, you didn't send all of them but, it is enough I think. You can find it in the attachment the difference.

at last, I think the logic that we have in our system is not enough to calculate EOH (time base, start base).
 

Attachments

First of all, thank you for your answer.
We have the same totalizer in our (F6B - Mark VIe) logic. I compare each pin of your totalizer with ours. of course, you didn't send all of them but, it is enough I think. You can find it in the attachment the difference.

at last, I think the logic that we have in our system is not enough to calculate EOH (time base, start base).
Thank you for this message and your answer..

I will review the file that you sent..
The reason I did not send totalizee function block, is because it is for Frame 9FA..ok we know that it can be similar to Frame 6B...but the page /function block is not easy to read as it is written on 2 differents pages and some signals names are difficult to read

James
 
Hi

Here the answers of the questions that you submitted on the pdf file:

L30FT_L: It is a signal name called "Total fired time on Liquid fuel logic"

L30CLFS: signal name "Fast load starts counter logic"
 
Hi

Here the answers of the questions that you submitted on the pdf file:

L30FT_L: It is a signal name called "Total fired time on Liquid fuel logic"

L30CLFS: signal name "Fast load starts counter logic"
thank you for your quick answer. I asked about "L30FT_L2" signal. we have L30FT_L as I send in the attachment file.

would you please tell me how do you calculate your EOH in your power plant? I mean you calculate it by hand or GE have its own extension logic for this reason that automatically can calculate the EOH?
 
Actually there is no designation on signal name for L30FT_L2 BUT I see a associated signal designation name called L30FT_L2_CNT...Which is called " Total liquid fired time current"
 
This is app code that I got from another site ...I am Controls systems Technical field advisor, Iam not working on a plant as you may think...

I worked on multi sites worldwide ( Worked on 25 projects in18 countries till now )

The thing is that i worked with GEEPE in Belfort ( Frame6B maker ) back in the days .....
 
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