Thermodynamic behaviors of coal spontaneous combustion under different CO2 concentration

For identifying the inhibiting effect of CO2 on the exothermic properties of coal oxidation at low-temperature, a Differential Scanning Calorimeter (DSC) was used to monitor the heat flows with coal temperature at different CO2 concentrations atmospheres and multiple heating rates. The results show that the DSC curve of the coal low-temperature oxidation process could be divided into three stages: rapid endothermic, slow endothermic, and exothermic stages. Compared to the air atmosphere, CO2 has different degrees of inhibition in the various stages of coal oxidation and heating. By Flynn-Wall-Ozawa (FWO) method, it revealed that the activation energy of coal oxidation decreased by 12%~19% and 10%~25% in the fast and slow endothermic stages. In the exothermic stage, the activation energy of coal oxidation increased by 20.5%~37.9%. The inhibitory effect of CO2 concentration on the exothermic stage of coal low-temperature oxidation process was superior to that in the endothermic stage.