Study on Reaction Kinetics of Soot Oxidation in O₂/CO₂ Atmosphere

To study the reaction kinetics of soot oxidation in O₂/CO₂ atmosphere, thermogravimetric analysis was conducted with focus on the influence of oxygen concentration (φ(O₂)), so as to carry out a comparison with that in O₂/N₂ atmosphere, and to obtain the quantitative relations between φ(O₂) and the kinetic parameters including apparent activation energy (E) and frequency factor (A) for soot oxidation under oxy-fuel combustion conditions. Results show that in O₂/CO₂ atmosphere, both the starting and ending temperatures of soot oxidation are higher, indicating that the reactivity is inhibited in contrast with that in O₂/N₂ atmosphere; with the rise of oxygen concentration in O₂/CO₂ atmosphere, the TG-DTG curve moves toward the lower temperature region, the maximum mass loss rate increases, and the reactivity improves significantly. Obvious kinetic compensation effect exists between A and E of soot oxidation. When the value of φ(O₂) is lower than 20%, both E and ln A have positive correlations with φ(O₂); whereas when the value of φ(O₂) is higher than 20%, both E and ln A have nearly no correlation with φ(O₂).