just one thing, you talked about purging of secondary nozzle of gas fuel! there no purge for secondary nozzle of fuel gas! just for secondary fuel nozzle, i am talking about what we have DLN-1 frame 6B."i am aware and i have information about the stage of premix steady state, my question is: can i switch OFF IBH with load, without load or just when GT is OFF? that is the reason I did not switch OFF because I did not the logic and behavior of GT after make it OFF. "
The transfer to DLN not only involves IBH, it also involves gas transfer purge valves that isolate purge air to the secondary nozzle and a vent valve that ensures less than 50 psi between the purge valves. The IBH is commanded to 100% at 95% speed and is only allowed 15% deviation from command to position.
You can switch IBH modes in primary mode < 1600 f combustion ref temp. you can also switch modes when the IBH is completely closed i.e. 0% IBH command signal loads > 80% of max load based on inlet temp.
Just from experience.....If you attempt anything else; the IBH simply cannot respond fast enough and the turbine WILL TRIP.
If you have a fuel oil mode, the IBH is probably disabled in logic when Fuel oil is selected.
Hopefully, CSA will/can explain it better than I.
see page NO#31 figure 65a Current MS6001B DLN fuel gas system
CSA, why you upset, i will talking about my self, always, when i face a problem i visit control automation and get the best answers from you and the friends, without pay any things, just thanks, i dont have a problem my friend, i am just thinking what if i need in any case to switch-off IBH! even when i asked my question, i did not mention that i have a problem, and when you ask me, also i answered your questions. sorry for friends here because my question is not useful. i will not switch-off IBH ever never.AhmedSnot,
EVERY FRAME 6B IS NOT LIKE EVERY OTHER FRAME 6B!!!!!!!
As the publication Curous_One shows, there are several types of DLN combustion and fuel delivery systems--you were asked about the configuration of yours early on, but you have not chosen to provide that information.
I do seem to be surprised that at least one of the DLN-I fuel gas system variants does not have purge air on the secondary nozzle--but, as mentioned you have not told what the configuration of the gas fuel system is for YOUR unit--WHICH IS NOT LIKE EVERY OTHER FRAME 6B!!!
When you enquire of strangers for assistance and they ask questions to try to help provide the most concise and helpful information it's a good idea to provide the information they are requesting to get the best possible response. If you wish to pick and choose the questions you believe to be relevant, then you're not likely to get the best information.
We get paid exactly the same amount as you paid to post your question here: Nothing. We do it because we want to help spread knowledge and experience. If you can find a better source of information at the same price, feel free to avail yourself of it. BUT, if they aren't asking similar questions (such as about the gas fuel system configuration) you should be prepared to get incomplete information.
Unless, of course, whomever is providing the answers has exactly the same Frame 6B (including the gas fuel system!) as you are operating at your site.
You know, you were also asked why it was felt that IBH needed to be disabled (turned off). And, again, no real good response. The purpose of IBH, as explained in the publication, is to allow the unit to operate in Premix Steady State for a wider load range, say from approximately 45% to 100%, instead of the typical 80%-100% only possible without IBH. With IBH on during starting and loading, the unit will transition to Premix Steady State at around 45%, instead of the 80% or so without IBH on. During unloading while in Premix Steady State the unit will remain in Premix Steady State down to approximately 45% or sometimes lower, instead of transitioning back to Lean-Lean at around 80% load.
If you are even considering operating the machine for extended periods in Lean-Lean, or Extended Lean-Lean, or even Primary Mode, you should know that GE has factors for the number of fired hours of operation in those modes that can quickly increase the need to perform scheduled maintenance. For example, one hour of operation in Extended Lean-Lean is equivalent to 10 hours of operation in Premix Steady State! Lean-Lean operation is also a pretty high rate compared to Premix Steady State, if I recall correctly. (Though many places in a certain region of the world routinely ignore those recommendations, preferring to operate their Frame 6Bs as if they had conventional combustors, and if they can't get to or stay in Premix Steady State they just don't. And, then they are always surprised to find hot gas parts issues. They scream (yes; that happens a lot in that part of the world, too...), "Why did the Mark* let me continue to operate the turbine in Lean-Lean or Extended Lean-Lean without shutting down or tripping?!?!?!!!?? It's the damn Mark*'s fault!" No, it's not actually; if the Mark* were programmed to shut down or trip for every less than ideal operating condition it would have a reputation as an unreliable turbine control system. It is presumed that operators and operations supervisors understand the units they are operating, and will act accordingly to protect the unit. AND, if the unit just must stay online, then that's an option that should only be exercised with due acknowledgement.)
Anyway, I digress. And I exit this thread with best wishes for obtaining a proper answer.
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by Seth Price