Computational and Experimental Study of Premixed Combustion at Ultra Wet Conditions

Humidified gas turbines (HGT), operating with humidified air, promise a higher efficiency compared to dry gas turbines, as well as reduced NO_x emissions. In this study, premixed, near-stoichiometric combustion was investigated for gas turbine applications at ultra wet conditions with steam levels up to 35w%. Based on a generic burner, an experimental study was conducted for the combustion of natural gas at atmospheric pressure. The influence of humidity on emissions and flammability limits was investigated for different inlet temperatures, swirl numbers, and fuel injection strategies. At near-stoichiometric conditions, a degree of humidity of 35w% was achieved with a stable flame and single-digit NO_x and CO emissions. In experiments conducted in a water tunnel, the flow field of the combustor was investigated using Laser Doppler Anemometry and Laser-induced Fluorescence. In addition to the experiments, a kinetic assessment of the emission formation was conducted with a reactor network, using a combination of several perfectly stirred reactors. The results of these simulations confirm the experimental findings.