GE Frame 9E swirl chart

Hi All,

I am looking for Swirl chart for GE Frame 9E turbine that contain speed range (firing to FSNL). One of the 9E diesel fired turbine that we operate has exhaust temperature fluctuation on TC 18, 19 20 and 21 during the speed range of 680 rpm to 1200 rpm.
Flame scanner #2 flame drop from 750 rpm to 1200 rpm.

Any idea where the issue would be?

any help would be highly appreciated.

First question is: When did this problem start? After a maintenance outage? After the liquid fuel bypass valve LVDTs were "calibrated"? After the liquid fuel bypass valve servo-valve was replaced? After a trip from load?

Swirl charts for speeds less than rated are difficult to find, if not impossible.

HOWEVER, since you are experiencing the problem you are describing while accelerating on liquid fuel you have an even better tool than a swirl chart for locating problem combustors: the liquid fuel flow divider gauge and selector handle.

It will take two people to take the data, but as the unit is starting up and during the speed range you are experiencing the problem in one person will rotate the selector handle and read the gauge out loud to a second person who is going to write down the pressures. Any pressure which is approximately 10% higher or lower than the average of all the pressures is suspect. Problems can be caused by plugged (choked) liquid fuel nozzles, plugged/choked liquid fuel check valves (immediately upstream of the fuel nozzles), failed liquid fuel check valves (springs broken; poppets worn and or broken; etc.). If the unit is dual fuel (gas/distillate) the problem can also be caused by leaking or failed atomizing air check valves--and that can be verified by observing the Tell-Tale Leakoff on the right side of the Accessory Compartment under the walkway for any liquid fuel passing out of the pipe (which would indicate a leaking or failed atomizing air check valve (or valves).

Have a look at the Fuel Purge P&ID and the Atomizing Air P&ID and the Liquid Fuel P&ID.

Now, having said all of the above, problems such as you are describing at the speed range you are describing are NOT uncommon when the firing and acceleration FSRs are slightly lower than they should be. This could just be a matter of simple Control Constant adjustment, and most likely is.

Other things which can cause such problems include: Low liquid fuel forwarding pressure (caused by plugged liquid fuel forwarding pump suction strainers, or dirty low pressure liquid fuel filters, or even dirty high-pressure liquid fuel filters (again--refer to the appropriate P&IDs for details on these strainers and filters). I have also seen problems with filter vessels not properly vented of air causing problems especially during firing and acceleration. Some units also have multiple low-pressure liquid fuel filters (one on a skid located outside the Accessory Compartment, and one located inside the Accessory Compartment.)

But, with the information from the liquid fuel flow divider gauge using the manual selector valve you can narrow the problem down to specific combustors and/or their fuel nozzles or check valves. Pulling these fuel nozzles and check valves and checking them will almost always result in reduction in the problem you are describing. Another problem that can cause plugging/choking of the fuel nozzles is carbonization of liquid fuel in the fuel nozzle assembly, resulting in poor pressure atomization at low flows.

Finally, it's a good idea to look at the booster atomizing air compressor piping and any gravity-operated check valves or solenoid-operated isolation valves to make sure they are working correctly.

For units burning gas fuel about the only way to track an issue with high spreads is to use a swirl chart or use the tried-and-true rule of thumb to work backwards against rotation about 90 degrees and start with the can/nozzle closest to that location and if that's not the can/nozzle with the problem start pulling the can/nozzle on either side of it, and continuing until the problem is found. Because there's no way to measure individual gas fuel nozzle pressures as there is with liquid fuel (using the liquid fuel flow divider), troubleshooting gas fuel spread problems can be little more involved. SOMETIMES, swirl charts can be helpful for this on gas fuel but not always. But, with liquid fuel using the liquid fuel flow divider gauge and selector valve it's much easier to spot trouble. It doesn't always point exactly to the root cause of the problem (because it might be a fuel nozzle problem, or a check valve problem) but it always points to the area where the problem is--it's up to the personnel to then zero in on the problem understanding what the possible causes might be. Using the P&IDs is very helpful for that, too.

Best of luck! Please write back to let us know what you find. Don't forget, if this problem started after a maintenance outage when some "work" was done to the turbine control system and/or the liquid fuel bypass valve and its LVDTs or the servo-valve of the bypass valve, that could be another cause of the problem. (Incorrect LVDT calibration is VERY OFTEN a cause for something like this that was working better before the calibration and now works worse after the calibration.)

Looking forward to hearing back from you!

Thanks for your detailed reply. the issue has started since we chage over the fuel from jet fuel to Diesel.
ill keep you posted on the findings.


This would have been very excellent information to know from the beginning.

There is a pretty good difference, I imagine, in the heat content (calorific value) of jet fuel and diesel fuel. I would imagine jet fuel has a higher heat content (calorific value) than diesel fuel. So, that probably means the firing and acceleration FSRs need some adjustment/tuning to account for the difference.

There's no easy way to do this. It's mostly trial and error, sorry to say. You might try getting the heat content (calorific values) of the two fuels, and then calculating the difference (in percent) and try increasing FSKSU_FI and FSKSU_WU by that amount to compensate for the reduced heat content.

But, it's still a guess in my book. And still subject to some minor changes, probably, for an optimal start-up.

Again, this information would have saved a LOT of time. That's not to say that there aren't problems with check valves or fuel nozzles that are hampering the establishment of flame and the maintenance of flame. But, it's probably the difference in fuel heat content (calorific value) that's mostly responsible for this issue.

lt's NOT uncommon for flame to flicker during warm-up and early acceleration. One of the reasons for this is if the exhaust temperature increase during firing and warm-up is high (hits or exceeds the exhaust temperature limit, (TTRX)) that can clamp the amount of fuel (FSR) and cause the flame to flicker. This can also happen if the acceleration rate (TNHA) exceeds the allowable acceleration rate (THNAR) during warm-up and initial acceleration.

There's a lot that goes into the determination of what the correct firing and warm-up FSRs should be. And every machine is different (unfortunately); every Frame 9E is not like every other Frame 9E (which would be nice, but it just doesn't happen--ever).

Hope this helps! That's as much information as I can give or want to give. It's a site determination at this point how to proceed. AGAIN, this could be a combination of problems (not just ONE like EVERYONE always wants it to be!!!) that is contributing to the flame flickering. And, you should really have a knowledgeable person come to site to help with troubleshooting, or contact the OEM with the new (and old) fuel information (UHV, LHV, Metane, Btu, specific gravity, etc.). It's also possible that the fuel nozzles are not really designed for the difference in fuel characteristics and should have the internals changed.

Best of luck!