A comparative kinetic study between TGA & DSC techniques using model-free and model-based analyses to assess spontaneous combustion propensity of Indian coals

Kinetic study of coal was carried out using simultaneous thermal analysis (STA) technique to assess the spontaneous combustion propensity of coal samples collected from various Indian coalfields having both fiery and non-fiery seams. The kinetic parameters were estimated by using both model-free and model-based analysis for both TGA & DSC data. The model-based method comprises four different consecutive reaction steps, viz. A→B→C→D→E for the spontaneous combustion process and the second reaction step (B→C) were used for this investigation. Chemometric analysis was applied to know the relation between the proximate analysis and activation energy of the samples using model-free and model-based techniques. The activation energy for the second reaction step of the model-based method for both TGA and DSC data showed a good relationship with the standard methods i.e., crossing point temperature (XPT) and Tgign of the samples. It indicates that the activation energy values at the oxidation stage (2nd stage) play a significant role in the spontaneous combustion propensity of coal. The study also reveals that the model-based analysis provided better results in comparison to model-free analysis to assess the spontaneous combustion propensity of coal