We see that in our turbine which is running at 100 % load suddenly switches to lean-lean mode ( 20-40 % load ). Have any body seen this type of issue, or waht are the sensors that are needed to look into to diagnos this issue.
depending on what kind of Low NOx system you have... could you give more data?
also... first thing is call the OEM... if you so require they will send a field engineer to troubleshoot the problem...
these load swings are not good for the unit at all and will damage the combustion hardware very fast.
What model-series turbine are you operating? What is the DLN series? DO you moitor combustor dynamics? when was the last mechanicaloutage and what repairs were made?
Definately need more info, but I have seen similar problems with my GT when we've had problems with our gas fuel supply -eg loss of performance heating or even a dodgy input into our gas chromatograph throws out the Wobbe index correction which deloads the GT. Send some more information.
Caemaniac
If you are using your terms correctly in saying "Lean Lean Mode" You have a GE Unit most likely with a DLN 2.0 or DLN 2.0+ Combustion system.
Lean Lean Mode is a diffusion mode where gas is being directed to the Primary Fuel Nozzle and the Tertiary Premix Fuel Nozzles.The Gas Turbine runs in this mode from approximately 81% speed to the engine reaches TTRF1 (combustion reference temperature) which corresponds to about 40% base load with extended turndown options and 70% base load without extended turn down options.
The unit will experience what is called a "runback" from Premix to Lean Lean if some event ocurrs in the combustion operation. DLN 2 and 2+ should be giving alarms that will acompany these events.
Can you provide details on the alarms present? Would also help to know if you are runing a Mark V or Mark VI Control as they are completely different when troubleshooting.
What is the maximum temperature a gas generator bearing can withstand. I believe that the gas generator bearing is for a Rolls-Royce Avon engine for industrial engine.