Prediction of coal stockpile autoignition delay time using micro-calorimeter technique

Spontaneous ignition of coal is one of the major challenges faced by coal industries, which results in a great loss and energy wastage. To evaluate the thermal behavior of coal powder and predict the autoignition delay time (AIDT) of coal stockpile, a C80 micro-calorimeter was employed to detect the thermal behavior of coal at elevated temperature. The reaction heat, reaction order, frequency factor and activation energy of coal were obtained from the experimental data. Based on the Semenov model, the self-heating oxidation temperature (SHOT) and temperature of no return (TNR) were calculated for the 25 kg coal stockpile. Assuming that the coal stockpile is under quasi adiabatic conditions, its AIDT was predicted and compared with the experimental result. The comparison indicates that the micro-calorimeter technique is a useful way to access the safety of coal stockpile, which can be widely used in large scale coal storage and transportation.