9FA and DLN 2.6+ Combustors

J

Thread Starter

Jim Crown

Good Morning All,

I do not have a great deal of experience with the DLN2.6+ combustors however; as a consultant in the power industry have been asked numerous questions concerning duel fuel operation with the 2.6+ units.
Most of the questions I have been able to answer either through previous experience or through research. One question I have not been able to answer is: With a 9FA, utilizing 2.6+ combustors and in duel fuel service, can I switch from fuel oil to natural gas operation at 90% load. I have researched this, have spoken to several GE people and still do not have a solid answer. Can you help?
 
Jim Crown,

Good morning to you, also.

I've heard of people attempting this at high load (at or near 90% load) but without success. All of the gas fuel valves have to operate in perfect sequence (including purge valves) and it just usually doesn't work out very well. Especially if the gas fuel needs to be heated (performance heating).

It's a much better idea to reduce load to around 25-40% and then transfer from liquid to gas, and load the machine back to near base load, allowing the fuel staging to occur in its normal fashion instead of trying to go straight to gas at 90% load.

The unit probably uses water injection for NOx reduction while operating on liquid fuel, also, so there's yet another consideration which must be taken into account. I haven't heard good things about ramping water injection down when transferring fuels on F-class machines with DLN combustors of any vintage.

While the control system may allow the selection and initiation of a fuel transfer at high load, the complexity of staging fuels and water injection can be very problematic. Tripping from high load is <b>not</b> very desirable for F-class turbines.

Were these conventional combustors, this would still be iffy though not so much going from liquid to gas; still a high pucker factor going from gas to liquid, though, at high loads even with conventional combustors.

Hope this helps!
 
Top