Ignition of high ash coal particles

This article examines the combustion kinetics of high ash coals in oxidizing media. Microcine photographs of individual coal particles were taken inside a quartz microfurnace tube, with a weak oxygen flow supplied. The photographs and the physicochemical characteristics of the coals indicate that both the ash content of the fuel and the ratio of the thermal equilibrium loss temperature and the ash fusion point determine the differences in ignition. The porous mineral residue has no practical effect on the interaction between carbon and oxidizer for coals with a low ash content or fusible ash. Two limiting ignition mechanisms, thermal and thermokinetic, are identified. It is demonstrated that for coals of various brands, the ignition mechanism is determined primarily by the coal ash content and the ratio of the critical dispersed system ignition temperature to the fusion point of the fuel mineral component.