Self-ignition characteristics of coal stockpiles: theoretical prediction from a two-dimensional unsteady-state model

This paper presents the results of calculations from a two-dimensional unsteady state model of a coal pile that self-heats. The influence of pile height, slope angle of bed, particle diameter of coal, and coal moisture content on spontaneous heating of coal stockpile was investigated. The physical system is a particulate pile several metres high. It has been found that spontaneous ignition can occur if two primary conditions are satisfied: first, the height exceeds some critical value, typically in excess of 2 m; and second, if there is sufficient time, where ignition times can be of the order of 15 days or more.