Hi all,

I’m having some difficulty understanding the firing mode logic for DLN2.6+. I believe the confusion might be related to my understanding of the hardware arrangement.

In our configuration,
We have only three fuel gas manifolds, PM1, PM2 AND PM3.

we have a five-around-one nozzle layout (a total of six nozzles). The center nozzle is PM1, which operates in premix mode only, while the outer nozzles are PM2 and PM3— two and three nozzles respectively— contains both premix and diffusion modes.

According to the manual:

Mode 3 involves PM1 and PM2 being active.

Modes 6.2 and 6.3 involve all nozzles being in service.


My questions is..
Could you please explain which gas paths are active in each of the six nozzles during all operating modes?
And Which of the gas paths operates as diffusion?

Thank you in advance for your support

 

The following content may help.
https://pdfcoffee.com/dry-low-no-combustion-systems-for-ge-heavy-duty-gas-turbines-pdf-free.html
https://control.com/forums/threads/ge-9ha-dln-2-6-combustion-modes.47206/

 

The following content may help.
https://pdfcoffee.com/dry-low-no-combustion-systems-for-ge-heavy-duty-gas-turbines-pdf-free.html
https://control.com/forums/threads/ge-9ha-dln-2-6-combustion-modes.47206/

I read both, but both doesn't match with 9FA 2.6+ operation mode #3 #6.2 and #6.4

 

@Abdullah Ghazy,

GE Operation & Maintenance Manuals are supposed to be specific to the machines they are provided with (hence the specific designation given each manual for each turbine or multiple turbines installed and commissioned at the same time). However, GE manuals are known for not covering many features and even specific operating conditions for the machines they are provided with. This is, in part, because technology changes quickly sometimes and sometimes specific requirements for specific sites and the machines installed to operate there can be different as well. (There used to be a method for distributing updated sections of O&M manuals, but that has fallen by the wayside over the last couple of decades as technology has changed rapidly.) DLN technology is an evolving technology (which GE considers proprietary), though GE likes to say it is a "mature" technology. It's mature in the sense that the fundamentals are basically the same, but the specific methods employed to achieve flame stability and operational stability from start-up to rated load and in between are often slightly to very different depending on the requirements of the application, including the anticipated fuel(s) which will be burned.

My recommendation is get yourself copies of the Gas Fuel System P&ID--in the largest printout you can obtain--and then review and study them to understand how the fuel is "staged" (directed to different nozzles) during starting and loading and unloading. That's the place to start--because, unlike the Operations & Maintenance Manuals the P&IDs ARE specific to the machine they are issued for. This will be the best way for you to begin to understand what devices the turbine control system use to stage the fuel to the different manifolds and fuel nozzles.

As to which fuel paths and nozzles have diffusion flame, again, I believe the Gas Fuel System P&IDs will have the best visual representation of how the fuel flows in the nozzles. Diffusion flame has several advantageous uses in the GE DLN combustion systems, and that can also affect how the combustion system (nozzles and control valves, and any fixed orifices and even solenoid-operated valves if present (and if they are present they would be shown on the Gas Fuel System P&ID). In this way, you should be able to at least begin to understand how GE does their DLN magic--which GE consider to be highly proprietary information and only shares minimal detailed information in an effort to protect the technology and methods they spent time and money developing and fine-tuning.

You may also be able to find in the Parts List manual provided with the machine(s) a section with cut-away diagrams of the fuel nozzles and endcovers that will most likely be very helpful to your search and knowledge.

Again, it may be that the machines at your site use a variety of fuels from various parts of the world (LNG) and can have a wide Wobbe range and composition and heating values. This, too, affects some design and operation considerations. It would be great if when we wanted an explanation for our understanding we could turn to the Operations & Maintenance Manuals for more detailed information. But, this is often not the case.

Now, since your site uses F/FA-class technology it's very typical that the ownership and/or the operation and maintenance company have a Contractual Services Agreement (CSA) with the packager of the equipment (usually GE) to provide parts and service and even technical advice and information. If your site has that capability to ask technical questions I strongly suggest you take advantage of. HOWEVER, I also strongly suggest you review and study the Gas Fuel System P&ID first so you can ask better questions. DO NOT be surprised if they ask for operational data--that's a pretty standard tactic used to find out how much the questioner really wants the information. And if the site has a CSA then it's also VERY likely the site is continually monitored during operation by a Remoted Monitoring & Diagnostics operation.

I wish I could answer your questions directly, but without access to the O&M manuals AND the Gas Fuel System P&ID AND the application code running in the Mark* turbine control system (I presume it's either a Mark* VI or Mark* VIe). (I read the documents attached to a response to this thread and I too was a little "confused" about diffusion flame and didn't see mention of a couple of the modes you mentioned. Again, GE considers DLN technology to be very proprietaty and don't want competitors or third-party parts manufacturers to be able to reverse engineer the designs.) This is about as much as I can offer. Any gas turbine technician or engineer who is really committed and motivated to learn and understand a GE-design heavy duty gas turbine needs to have their OWN copies of all of the machine's P&IDs and go over them, repeatedly. Many people (mistakenly) believe that they don't need to study and learn P&IDs--but that's complete nonsense. I suggest getting them printed (or copied) in the largest size possible--because the really committed and motivated technicians and engineers will make notes on the drawings and highlight important information as they discover and understand things. GE P&IDs seem intimidating--in the beginning--but, in truth, they are some of the easiest and simplest P&IDs for large rotating equipment in the world. AND, again, the P&IDs provided with a machine (or machines) are SPECIFIC to the machine. And, without understanding the machine P&IDs it's not possible to really and truly understand, operate and troubleshoot the machines.

And that's a fact. Get a large-sized copy of the machine P&IDs. Study them. Ask questions if you don't understand. (Some symbols used on the GE P&IDs are not used by other organizations when drawing P&IDs--and the same can always be said of other organizations symbology practices!), but if you can photograph or take a snippet of symbols you have a problem understanding and attach them to a Control.com thread, we can probably explain. You will probably find most, if not all, of the answers you seek will be on the P&ID.