Fingerprint of Hydrocarbon Emissions from Gas Turbine Exhaust at Low Power

Measurements in exhaust plumes from a variety of gas turbine engines indicate that many hydrocarbon emissions, including aldehydes, are linearly related. Hence, HC1 approximately equal to a HC2, where 'a' is constant for any two HC pairs and is independent of engine type or power condition. This study explores possible causes for this 'universal' fingerprint for hydrocarbon emissions. We apply simplified analyses to idle and part power operation at which hydrocarbon emission levels are large enough to be identified and be quantitatively determined; the emission indices are on the order of 1 gram/kilogram of fuel. We consider the relations among intermediate hydrocarbon species present in laminar flame reaction zones found in freely propagating and both premixed and non-premixed opposed-jet (strained) configurations. The analysis is extended to a single stirred reactor and then to a network series of reactors. Full detailed chemical kinetics and a binary surrogate mixture for jet fuel are utilized. Finally, the results are interpreted to identify probable explanations for the linearity among hydrocarbon emissions. Specifically, we conclude that this linear scaling is due to quenching of lean, premixed mixtures.