Turbine Technology Services Corporation (TTS), a full-service gas turbine engineering services firm based in Orlando, Florida, has been featured on the current edition of Combined Cycle Journal, an international power engineering publication, where senior systems engineer Mitch Cohen shared his knowledge on a common threat to 7FA gas turbines: lean blow-out trips.
As an expert with more than two decades of experience in the design, operation, and maintenance of Dry Low NOx (DLN) combustion systems for gas turbines, Cohen contributed to Combined Cycle Journal (CCJ) by providing details on the detection and prevention of Lean Blow Out trips, also referred to as LBOs.
Cohen’s extensive knowledge and experience with the optimal functionality of gas turbines has provided him with a unique perspective on the LBO problem affecting 7FA DLN-2.6 gas turbines as widespread use of these models expands, now numbering more than 500 units in operation.
According to Cohen, the reliable operation of the DLN-2.6 combustor requires precise control of the combustor fuel/air ratio that contributes to achieving desired NOx and CO2 emission levels, while also maintaining low combustor dynamic levels and adequate flame stability over the DLN operating range.
As TTS’ senior systems engineer, Cohen explains that a failure to achieve this required fuel-to-air ratio control can result not only in the failure to maintain emissions limits, but in many instances, induce a flame out trip of the turbine – an LBO.
"A Lean Blow-Out trip can cost operators tens of thousands of dollars, both in lost generating revenue and increased maintenance costs because of reduced overhaul intervals," adds Cohen, who writes many of TTS’ technical documents and case studies. "With today’s large fleet of 7FA operators facing similar consequences, this article should resonate well in the power generation community."
The CCJ article provides operators with practical information about the causes and means of preventing LBO trips in DLN-2.6 combustors, including examples of actual Lean Blow-Out troubleshooting procedures to illustrate how operators can learn about the signs of impending LBOs and prevent a trip before it occurs.