Constraction of coal gangue artificial thermal storage and analysis of spontaneous combustion thermal energy potential

Aiming at the problems of environmental pollution and energy waste caused by spontaneous combustion of coal gangue mountain in Yinying Coal Mine in Yangquan City, Shanxi Province, a scheme of constructing artificial thermal storage with coal gangue as raw material and utilizing internal spontaneous combustion thermal energy was proposed. The dynamic change law of oxygen consumption rate, heat release rate and residual amount of combustibles in spontaneous combustion of coal gangue was quantified. A multi-physics mathematical model of temperature field, seepage field, oxygen concentration and residual amount of combustibles was established. The heat-supply potential of coal gangue heat storage was evaluated. The results show that the temperature field with uneven spatial distribution in the artificial thermal storage produces the chimney effect, which increases the seepage velocity and enhances the convective heat transfer. The oxidation reaction of coal gangue in the high temperature area is faster, the residual amount of combustibles is less and the attenuation of oxygen concentration is larger. After 720 d of continuous heating, the temperature difference between the inlet and outlet of the U-tube exceeds 10 ℃, and the temperature of the air flowing out of the outlet exceeds 55 ℃. At the same time, the volume of coal gangue with more than 60% of the remaining combustibles still exceeds 94%. The study believes that artificial thermal storage built with coal gangue can provide high-quality heat for a long time.