Wobbie index

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Thread Starter

pawan

Can anyone let me know clearly the importance of wobbie index in gas turbines and why this wobbie index is applicable for only GE9FA machines. Why the turbine gets unloaded when wobbie index protection acts?

Is there any difference between wobbie index and modified wobbie index?
 
pawan,

It's not only for GE 9FA machines. And it's only for machines that can have gas fuel from various sources (LNG, or different gas fields) or which is heated (performance heating).

Have you tried searching the World Wide Web using your preferred search engine to understand Wobbe Index and it's relation to fuel flow and characteristics?

I can't answer the question of specifically what role Wobbe Index plays--again, I believe some of that is proprietary--but I do believe that because of the nature of DLN combustion systems and the propensity for them to experience high dynamic pressure oscillations in the combustors that monitoring fuel characteristics is important to prevent catastrophic damage to nozzles, combustion liners, and transition pieces.

And, there's also that bit about Premix Combustion, where diffusion flame does not exist. Again, I believe this is mostly GE proprietary information.

If your site has a Remote Monitoring & Diagnostics agreement or a Contractual Services Agreement with GE or one of its packagers, you could probably ask for a better explanation--from the source. If you feel you are experiencing nuisance and inappropriate problems with the sequencing, you can always ask for a review of the situation but you need to provide good information (Trends, VIEWn files, etc.) about the events.

Another good source of information about F-class machines are the GE Users Groups. I know there is one for the 7F machines, and I would be very surprised if there weren't one for 9Fs as well.

Another possible source of information is GE Controls Connect. You can search control.com for the precise URL, register (if you haven't already done so), and according to the GE employee who posted the URL on control.com you can ask for help by email or telephone. Again, be prepared to provide actionable details--not just anecdotal information.

But, it's not just <b>YOUR</b> unit that experiences these issues. And, isn't the <b>real</b> issue controlling the fuel temperature and characteristics? Because it sounds like you are really looking for justification for "disabling" the protection because of other problems, instead of resolving the root cause of the problem.

You have several possible avenues above for help with your problem. It would seem, since you've posted this issue here before, that there isn't anyone who can provide the precise information you are looking for. So, use the other potential sources--and let us know what you learn! "Feedback is the most important contribution!"(c) here at control.com! It's really what lets others know if the information was helpful or not--and that's the real benefit of forums like this. It's not just for one person, but for many--and feedback is the part that makes this site work so well for GE-design heavy duty gas turbine control-related issues.
 
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