Improvement of ignition prediction for turbulent pulverized coal combustion with EDC extinction model

In this paper, Eddy Dissipation Concept (EDC) extinction model, for the first time, was implemented to simulate turbulent pulverized coal combustion with the consideration of the effects of intermediate species and the interaction between chemical kinetics and turbulence. Chemical reaction of the vital gas reactions is set to cease in the fine structures wherever the characteristic turbulent time (τ_tur) of Kolmogorov scale eddies is smaller than the characteristic chemical reaction time (τ_ch) of volatile matter. The improved model was applied to simulate the ignition and combustion of the primary air (mixture of pulverized coal and air) crossing over a bluff body flame holder. Compared to the conventional EDC model, the EDC extinction model barely changes velocity distributions, but predicts a lower average temperature and a higher volatile matter concentration adjacent to the flame holder. The ignition of the primary air is delayed and blow-off is accelerated. The results are validated by reported experimental data. With EDC extinction model, prediction of temperature profiles is closer to the experimental data than those with conventional EDC model.