This paper describes the design and initial testing of a second generation, lean-premixed combustor for a 6100 horsepower industrial gas turbine. The full scale, prototype combustor liner employed augmented backside cooling (ABC) as a means of reducing NOx and CO emissions. A thermal barrier coating (TBC) was applied on the liner hot side to reduce thermal flux from the flame zone. The goal of the effort was to demonstrate that the avoidance of film-cooling for the combustor liner would allow emissions reductions in a lean-premixed combustion system.
Testing of the combustor was conducted in both low and high pressure environments. The testing demonstrated that the use of trip-strips for backside cooling provides an effective means of reducing CO emissions. The lower CO levels can be exploited by lowering flame temperatures to achieve lower NOx emissions. Reaction quenching associated with film cooling is indicated as the cause of the higher CO emissions in more conventional liners. Cyclic rig testing showed the TBC to have good short-term durability. Long-term field testing is getting underway.