Modeling of processes occurred during heating and ignition of coal particles in methane-air mixture in the area of fire

Abstract

The study of combustion processes at high temperatures is associated with two main problems. The first of them is to determine composition and amount of possible combustion products, and to clarify thermodynamic properties of the mixture under various combustion conditions. The second problem is to determine amount of heat released during combustion and maximum attainable temperature of combustion or work which can be obtained if to apply the established simplifications and under the conditions in which combustion occurs. Great importance is given to predicting temperature indicators in the fire site when performing work in mine conditions on extinguishing and assessing the development of fires in mines. These indicators are important for the actual assessment of the state of the environment in the focus of its extinguishing, since they are control indicators for determining the cooling of the rocks of the massif and, ultimately, indirectly assess the fact of an extinct fire. In the article, the authors present a method for calculating parameters of the process of solid fuel combustion, which is based on the results of theoretical and experimental studies in the field of the theory of combustion of dusty fuel. By this method, the following parameters of combustion process are calculated: theoretical air consumption required for combustion of a unit of fuel quantity; volume of combustion products; composition of combustion products; enthalpy of combustion products at required temperatures and excess air; and calorimetric and theoretical temperatures of solid fuel combustion. By using the known dependences, the forecast of the temperature in the fire zone is substantiated for further development of new and improvement of existing methods. Some proposals developed for improving the estimates of the parameters of the state of the rock massif in the process of extinguishing a fire are considered. It is proposed, for example, as preventive measures, while determining indicator gases and evaluating their dynamics, to take additionally samples of coal before a fire and gradually heat them in laboratory conditions in muffle furnaces until the coal ignites, whereupon to evaluate their dynamics according to a laboratory experiment; then, when a fire occurs, it is possible to determine its real state by the dynamics of changes in the factually measured indicator gases. This proposal is not normative and requires further development, industrial verification and discussion. Keywords: coal particles, temperature forecast, area of fire, heat exchange, air, atmospheric composition.