An experimental study of N2 dilution effects on CH4–O2 flame stabilization characteristics in a two-section porous medium

Abstract N 2 dilution effects on CH 4 – O 2 flame stabilization in a two-section porous medium burner were experimentally investigated for its potential application to the destruction of highly N 2 -diluted CF 4 . The burner was made up of two axially-stacked silicon carbide foams having different pore sizes. Various flame behaviors, such as stable flame, flashback, blowout, extinction and transient flames, were observed and, for the stable flame, temperature distributions and exhaust gas emissions were measured. Results showed that the flame was only stable in a belt-like region on the domain of fuel flow rate and oxygen concentration. The region boundaries, termed as O 2 -enriched and O 2 -deficient limits, were determined for various equivalence ratios. It was found that our burner configuration was able to sustain the submerged combustion even under the N 2 dilution amounting to at least 10.4 times of CH 4 flow rate. In addition, temperature measurements showed that the stable flames could have their peak temperatures higher than 1600 ° C , which is known to be a thermal destruction temperature of CF 4 . These results may indicate that porous media burners can practically applied in destructing highly N 2 -diluted CF 4 with a reduced fuel consumption.