Thermodynamic behaviors of coal spontaneous combustion under different CO₂ concentration

ABSTRACT

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.

KEYWORDS:

• Coal spontaneous combustion
• CO₂ concentration
• characteristic temperatures
• exothermic intensity
• apparent activation energy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by The Youth Innovation Team of Shaanxi Universities (21JP070); the National Natural Science Foundation of China (No. 51974236,52174199)