The dependence of UV-visible emission characteristics in hydrocarbon flames as a function of flame equivalence ratio and total flow rate is examined for low-pressure acetylene/oxygen flames used for materials synthesis and for atmospheric-pressure methane/air flames typically seen in industrial boilers and heaters. In both flames, the OH and CH emission features show significantly different variations with respect to changes in equivalence ratio, while variations with changes in total flow rate are nearly identical. These results suggest that flame emission spectroscopy can be used as a sensitive, on-line process diagnostic for equivalence ratio monitoring in flame reactors.
