Experimental and numerical analysis of non-premixed oxy-combustion of hydrogen-enriched propane in a swirl stabilized combustor

Oxyfuel combustion is a promising carbon capture and sequestration technology. The use of CO₂ diluent in oxyfuel combustion can lead to flame instability. In this study, the effect of hydrogen enrichment on the blowout limits of propane oxyfuel flames under CO₂ dilution was analyzed experimentally and numerically in a swirl-stabilized, non-premixed combustor. Results show that increasing the hydrogen concentration from 0 to 30% extends the blowout limits of the CO₂ diluted oxyfuel flames by 2.5%. Hydrogen enrichment, however, was found to increase CO while lowering CO₂ emission as a consequence of the low residence time and competition for oxygen between the fuel species. In this regard, the minimum amount of CO₂ emission recorded (74.3%) corresponds to a maximum CO emission of (1.93%) at hydrogen concentration of 40%. Increasing the gases residence time in the combustor lowers the CO emission which is desirable since beyond certain limit, CO in exhaust gases can promote the formation of pentacarbonyls that can damage CO₂ transportation pipelines aimed at CCS. Decreasing the equivalence ratio from 1.0 to 0.9 also leads to a significant reduction in CO emission from 8000 ppm to <1 ppm. The flames, however, display better stability at higher equivalence ratios.