Nonlinear improvement of mathematical model of coal oxidation heat release and case study of oxygen concentration effect

It is important to accurately calculate coal spontaneous combustion (CSC) characteristic parameters for preventing and controlling coal fire disasters. Previous studies have shown that the process of CSC has nonlinear variation characteristics with temperature and O 2 concentration. Based on this, non-linear improved model of coal oxidation characteristic parameters is constructed in this study, and compared with the linear model calculation case. The results show a power function non-linear relation of coal oxidation characteristic parameters with O 2 concentration. The improved model can more accurately calculate the O 2 consumption rate (OCR), gas formation rate (GFR) and heat release intensity (HRI) in CSC. In contrast, Linear model can more conveniently and quickly obtain the characteristics of coal oxidation. The transcendental equation dichotomy solution of the reaction order considers the actual attenuation characteristics of O 2 in coal sample at the airflow direction, and the calculation result is more accurate. The average O 2 concentration hypothesis method can be used to calculate the reaction order more quickly, and the results are consistent. With an increase in temperature, the O 2 content sensitivity of the oxidation characteristic parameters first decreases and then increases. These findings have theoretical value for preventing and controlling coal fire disasters.