Pulverized coal particles are injected into a atmospheric premixed flat flame of $CH_4$, $H_2$ and air. Injected particle heats up, devolatilizes, ignites and burns out. During the coal combustion, luminous flames can be observed. In this study, the time-dependent changes of magnitude and shape of luminous flames of pulverized coal particles are observed by using a high speed video system. To measure the area of the flames quantitatively, image processing system were employed. Combustion model was set up to predict the experimental results. Using this model and experimental data, devolatilization reation coefficients of the coal can be derived.
