>I have read in other topics in this forum that raising or
>lowering the preset energy may lead to LEAN LEAN EXTENDED

>I did not understand how this gets?

Extended Lean-Lean mode occurs when something causes the fuel in the primary combustion zone of the combustion liners to be ignited into diffusion flame when the combustion reference temperature is above the setpoint at which the unit should be in Premix Steady State combustion mode.

There are MANY possible causes--unstable grid frequency, unstable gas fuel supply pressure, hot spots in the primary combustion zone (usually fuel-borne contaminants), excessive exhaust temperature spreads, problems with combustion liner integrity, fuel nozzle problems, gas fuel control valve instability, LVDT or pressure transmitter calibration problems, (everybody's favorite) servo valve problems, IBH control valve problems, improper igniter insertion depth(s), etc.

If the grid frequency was unstable and the unit was being operated in Pre-Selected Load control then it might be possible for the unit to experience a primary zone reignition event leading to Extended Lean-Lean combustion mode.

And if the unit has IBH enabled and active then the load will have to be MUCH lower than without IBH enabled and active to break the Premix latch and get the unit into a condition where it will be possible to get the unit to transfer back into Premix while re-loading the unit.

Higher than normal ambient temperatures can also cause problems, as can lower than normal temperatures, as DLN tuning may need to be redone if previously last dome at a much different ambient temperature. While the OEM likes to say DLN-I is a mature technology--it's still a long way from "set it and forget it." A long way away.

If you want help--you MUST provide the requested information/answers, ALL of them. Not just the answers deemed (by you) relevant. We need actionable data to be of any further help, as we aren't there beside you at your site. There are too many intangibles for us to guess any more than we already have and still have a hope of being correct. If you want more help and information you have to provide the requested information. There's no other way.

We want to be of help--but we need more, and better, information. Without it, we're guessing--just like you are. Alarms and operating conditions are important keys to helping you--and us--understand what may have happened. At this point, <b> based on the information provided,</b> there's nothing else which can be said.

A LOT of GE-design Frame 9E heavy duty gas turbines are operating in parts of the world where the grid frequency is not stable and the gas fuel supply pressure is not stable and Process- and Diagnostic Alarms are not given proper attention. Just because a unit is running doesn't mean it's running properly and can or will continue to do so--ESPECIALLY when equipped with DLN-I combustors AND while being operated in Pre-selected Load Control mode during abnormal conditions. Operators need training to be able to respond appropriately to alarms and unusual situations--or they will have to learn from experience. There is a saying, "Good judgement comes from experience, and experience comes from bad judgement." That's a fancy way of saying, most people learn from mistakes; hopefully they aren't bad mistakes.

If you haven't received proper training and are being expected to properly operate a multi-million US dollar machine, some mistakes are going to occur. Turbine control systems are NOT as sophisticated as salespeople and owners and many operations supervisors think they are. Operators need training or experience--and a lot of experience comes (without training) from making, or witnessing, mistakes.

From the information provided, the operating conditions were not normal, so why should the machine be expected to operate normally? It's not logical, and especially not for a DLN combustor-equipped machine. If you would be more specific about what caused the sudden load change to be necessary, it MIGHT be possible to provide a little more specific information. But, that means providing more information about the incident, and to get a really good response we need the answers to the requested information.

 

Maybe the attached document can help you. Have a read and come back to us if you need more help.

If you can help me .
I can start uint white out IBH valve
FYI i have 44%load