Combustion characterization of benzene-doped, hydrogen-rich coke oven gas surrogate mixtures: H2/CH4/CO/N2/CO2

This experimental study investigates the effects of benzene doping on the combustion and emission characteristics of hydrogen-rich, coke oven gas (COG) surrogate mixture, H 2 /CH 4 /CO/N 2 /CO 2 , to be called hereafter as COGb to distinguish it from and compare it with a different coke oven surrogate mixture, H 2 /CH 4 /CO, to be called hereafter as COGa. Unlike COGa mixture that includes only the major components of the industrial-grade coke oven gas composition, COGb also considers the minor components for the sake of a comprehensive understanding of the chemical and physical phenomena occurring at an industrial scale when burning coke oven gas mixtures. The purpose of benzene (C 6 H 6 ) – as representative of benzol (BTX) – doping of the COG mixtures is to investigate the direct and indirect impact of aromatic compounds on NO x formation during the hydrogen-rich combustion process. Different levels of benzene (C 6 H 6 ) doping (up to 5 % v/v) of industrial-grade, H 2 -rich COGb flames in a semi-industrial scale furnace under varying stoichiometric conditions allowed for collecting extensive data on temperature, exhaust emission, and chemiluminescence signature of important chemical radical species including OH ⁎ and CH ⁎ . The results highlight a benzene-driven, three-way interaction between flame temperature, NO formation, and soot inception in the coke oven gas flames. • Aromatic doping causes a non-linear, non-monotonic effect on NO emissions. • NO emissions depend on the balance between prompt and thermal NO pathways. • Flame temperature drops at stoichiometric and fuel-rich conditions due to soot. • Benzene-induced soot enhances radiative heat transfer from the flame.