Temperature profiles and extinction limits of a coflow water-vapor laden methane/air diffusion flame

The understanding of thermal and chemical effects of water addition to the fuel side of a diffusion flame is relevant for improving processes such as the combustion of methane hydrates, emulsified fuels and wet biomass, as well as for cases where water is intentionally added to the fuel stream, as for example in steam-assisted flares for the reduction of emissions. In this work, the role of water is evaluated by adding water vapor to the fuel side of a steady non-premixed coflow flame. The steady nature of the flame allows temperature profiles and extinction limits to be measured at different conditions of inlet fuel velocities, and with increasing dilution levels up to extinction. Temperatures are measured by thin-filament pyrometry (TFP) using a SiC fiber and a commercial DSLR camera. Results from Ar, N₂ or CO₂ diluted flames are also reported to compare the effects of water vapor with those of different diluents. Comparisons in terms of temperatures and extinction limits show close correspondence when adding equivalent levels of diluent thermal capacitance.