Model and simulation analysis of fire development and gas flowing influenced by fire zone sealing in coal mine

Fire zone sealing is an important approach to fire extinguishment and disaster relief. The study is aimed at investigating the distributions and evolutions of temperature and CH4 concentration fields during fire zone sealing and revealing the mechanism of sealing-induced gas explosion accidents. Firstly, the models of O2 consumption, heat production and products of coal combustion were constructed based on the Arrhenius equation of chemical reaction rate, and meanwhile the mathematical models of gases and temperature field in the sealing process were established. Besides, the variations of airflow volume, temperature and CH4 and O2 concentrations during and after fire zone sealing were numerically simulated. The results show that in the sealing process, the airflow into the fire zone gradually decreases, and air begins to flow out through the air intake at the later stage. After the completion of fire zone sealing, the temperature at fire source decreases briefly, then gradually increases and finally goes down. The temperature in the whole fire zone, except the fire source, also decreases first, then rises and finally falls gradually. The sealing raises the overall CH4 concentration in the fire zone, and the CH4 concentration at the air return side is always higher than that at the air intake side. When the sealed flow field gradually recovers to a steady flow field, the CH4 concentration goes up slowly under the influence of CH4 release. The research is of great significance for grasping the development of mine fire and the evolution of flow field in the sealing process and can provide guidance for the prevention of gas explosion accidents.