Effect of oxygen concentration on the heat release behaviour of bituminous coal over the complete spontaneous combustion process

The effect of different oxygen concentration conditions on the heat release behaviour of bituminous coal during spontaneous combustion was investigated. Thermal analysis experiments were conducted using differential scanning calorimetry (DSC) and laws governing feature peak changes. Heat flow curves were utilised to identify thermal reaction stages, and the impact of oxygen concentration on heat flows during spontaneous coal combustion (SCC) was assessed. The determinants of heat release rates according to temperature and different oxygen concentration conditions were shown. The heat release process exhibited varying heat proportions at distinct stages. Using the feature point analysis method, the DSC curves could be used to show the apparent activation energy of the total SCC process for different oxygen concentrations. Findings showed a noteworthy influence of oxygen concentration on the overall SCC process. As oxygen concentration increased, the characteristic peak of the heat flow curve appeared earlier, the range of heat release and its heat release temperature rose, and the apparent activation energy also increased. A critical oxygen concentration range, between 7 and 12%, was identified, causing fluctuations in the development process of SCC. This article provided a theoretical basis for further investigation into the SCC process and mechanisms.