Abstract
Quantitative laser fluorescence measurements of the concentrations of SH, S2, SO, SO2 and OH have been made in the post flame gases of a series of 10 atmospheric pressure, stoichiometric and fuel-rich H2/O2/N2 flames, containing 0, 0.25, 0.5 or 1% mole fraction of sulfur as H2S. The present discussion characterizes the chemistry of sulfur in the fuel-rich flames and also validates this fluorescence monitoring technique. A kinetic rate analysis of all the possible interactions has established that the sulfur chemistry is controlled by 8 fast bimolecular radical reactions. S, S2, SH, H2S, SO and SO2 are all coupled by fast reactions and it is only a result of the imposition of the non-equilibrated H2/O2 flame chemistry that controls their relative proportions. Termolecular reactions, other than providing a catalytic means for recombining excess H and OH concentrations are insignificant. The establishment of the equilibration of the reaction H+SO2=SO+OH provides a new method whereby fluorescence measurements of OH along with SO and SO2 can be used to determine both H and H2 concentrations in stoichiometric flames containing sulfur. This study constitutes the first systematic application of quantitative laser fluorescence measurements to a study of chemistry in a series of flames of varying composition and temperature. It demonstrates an important and powerful new method of great sensitivity and non-perturbing nature for the detailed study of combustion processes.
Published Version
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