Effects of wind barrier design and closed coal storage on spontaneous ignition of coal stockpiles

Abstract

Effects of wind barrier design on spontaneous ignition of coal stockpiles are investigated numerically. A wind barrier changes air flow pattern around a stockpile and spontaneous heating is affected by design factors of a wind barrier. The distance between a wind barrier and a stockpile is selected as a design factor in the stockpile with both a single and a dual barriers and air blowing from the bottom of the stockpile is applied aerodynamically by installation of a wind barrier. As the distance increases, spontaneous ignition is accelerated slightly with a single barrier and significantly with a dual barrier. A dual barrier with longer distance than a critical one doesn't have retard effect any more compared with the stockpile without any barriers. Air blowing induced by a barrier installation is effective when wind speed is higher than a critical one, but partial air blowing is not. Air blowing should be made from the entire domain of the bottom. As a method to root out spontaneous ignition, i.e., free of self-ignition, a closed stockpile is proposed here. Spontaneous heating depends strongly on the size of the silo covering the pile and it is verified that a compact one with a small volume can suppress ignition completely, where maximum temperature in the pile increases initially and finally, falls down below a critical value for self-ignition.