A novel method to suppress spontaneous ignition of coal stockpiles in a coal storage yard

Spontaneous ignition of coal stockpiles and its suppression in a coal storage yard are studied numerically. The process of coal ignition is simulated with several physical and chemical properties. The main purposes of the numerical simulation are to pursue novel suppression methods and verify them. Without losing essential features of spontaneous ignition, we adopt as simple numerical models as possible. The numerical approach is validated by comparison with the experimental data. The ignition mechanism is analyzed and essential elements for ignition are pursued. Based on the ignition mechanism, three new methods are proposed in this study. They are to adopt internal walls installed inside the pile, air blowing from the bottom of the pile, and a dual barrier installed at the front and the rear of the pile. Each method has been verified to retard spontaneous ignition time more fundamentally than the existing methods and the expected additional delay is about 10 to 30 days. But, air blowing is effective in suppression of spontaneous ignition only at higher rates than a critical rate. More delay can be made by a combined application of these methods. It is found that the proposed methods are viable and effective in delay of coal ignition.