Numerical study on the oxidation reaction characteristics of coal under temperature-programmed conditions

Abstract

To understand the oxidation reaction of coal and predict and control generation and development of coal fires, a one-step global dynamic model of the chemical reaction between coal and oxygen considering multi-material actions was established. A volume-averaged oxygen consumption rate (OCR) to evaluate the characteristics of the oxidation reaction of coal was proposed. The results demonstrate that, in the reaction between coal and oxygen, the dominant effects of temperature and oxygen concentration on the reaction rate of coal oxidation also change. There is a certain time-lag between changes of the temperature during coal oxidation and combustion and the reaction rate: the changes of temperature parameters fail to reflect the instantaneous reaction rate in real time. By changing the volume fraction of oxygen and the programmed heating rate, it is found that increasing the volume fraction of oxygen and the heating rate both can promote the reaction between coal and oxygen and reduce the hysteretic effects of heating in the reaction under external heating. Therefore, controlling the temperature storage conditions is beneficial to preventing the oxidation reaction of coal in its early stage, while changing the oxygen supply conditions can control the development of coal spontaneous combustion in its later stage.