Assessment of soot formation and thermal radiation in syngas flame using oxygen-enhanced combustion under lean mixing conditions and acetylene doping

Abstract

Combustion is a predominant global energy source, yet it contributes substantially to environmental degradation through greenhouse gas emissions and particulate matter, including soot. To alleviate these concerns, improving combustion efficiency and mitigating pollutant emissions are essential. Syngas, a hydrogen-carbon monoxide mixture derived from biomass gasification, offers a promising solution. This investigation examines the effects of oxygen-enhanced combustion, acetylene doping, and lean conditions on soot formation and thermal radiation in a confined flame. Soot formation was assessed via laser light scattering, while thermal radiation was analyzed using radiometers. Experiments were conducted at equivalence ratios of 0.7 and 1.0, with volumetric oxygen contents of 21 % and 30 % in the oxidant, and acetylene doping levels of 1 % and 5 % (by volume). The results demonstrate that acetylene doping significantly influences thermal radiation, particularly at 5 %, due to increased flame temperature. The findings reveal that combining oxygen-enhanced combustion with equivalence ratios of 0.7 and acetylene doping increases soot concentration trends compared to equivalence ratios of 1.0. However, soot levels for the 0.7 condition remain lower than those for the 1.0 condition. These results suggest that oxygen-enriched combustion in syngas flames enhances soot formation relative to non-enriched combustion.