Effects of equivalence ratios on the normal and inverse diffusion flame of acid gas combustion in the pure oxygen atmosphere

The experimental studies on the effect of equivalence ratios to the acid gas (H₂S and CO₂) combustion in the pure oxygen atmosphere was presented in a coaxial jet double channel burner. Three equivalence ratios (Φ = 0.8, 1.0 and 1.5) are examined to analyze the distribution of the flame temperature and gas composition in the normal and inverse diffusion flame along central axial (R = 0.0) and axial line at 3 mm (R = 0.75) in radial direction. The results revealed that acid gas combustion mainly occurred chemical decomposition of H₂S and oxidation of H₂S and H₂ at R = 0.0, while mainly occurred H₂S and H₂ oxidation at R = 0.75 in the normal diffusion flame. Reducing Φ increased the flame temperature and it is higher at R = 0 than that at R = 0.75 because of heat loss. It also increased the volume fraction of CO, H₂ and COS in the flame combustion area, while decreased downstream reactor because of occurring oxidation. CO was formed by the reaction of CO₂ and H, and H₂ primarily derived from chemical decomposition of H₂S. COS was generated by the reaction of CO₂ with SH, H₂S and S as well as the reaction of CO with SO and SH at R = 0.0, while was mainly formed by the reaction of CO with SO and SH at R = 0.75. H₂S mainly occurred the oxidation in the inverse diffusion flame. The temperature at R = 0.0 was still higher than that at R = 0.75, and it was higher than that in the normal diffusion flame in the combustion area. Increasing Φ promoted the formation of CO, H₂ and COS, and each gas under Φ of 1.5 was higher significantly. The Φ had no significant effect on the distribution of SO₂ compared to the normal diffusion flame, but changed the distribution of CO, H₂ and COS. It can be inferred that the content of CO, H₂ and COS will be more higher under Claus condition in the inverse diffusion flame.