Numerical simulation of combustion of a polydisperse suspension of coal dust in a spherical volume

The physical and mathematical model of combustion of the polydisperse suspension of coal dust was developed. The formulation of the problem takes into account the evaporation of particle volatile components during the heating, the particle emitting and the gas heat transfer to a surrounding area via the sphere volume side surface, heat transfer coefficient as a function of temperature. The polydisperse of coal-dust is taken into consideration. N - the number of fraction. Fractions are subdivided into inert and reacting particles. The oxidizer mass balance equation takes into consideration the oxidizer consumption per each reaction (heterogeneous on the particle surface and homogenous in the gas). Exothermic chemical reactions in gas are determined by Arrhenius equation with second-order kinetics. The heterogeneous reaction on the particle surface was first-order reaction. The numerical simulation was solved by Runge-Kutta-Merson method. Reliability of the calculations was verified by solving the partial problems. During the numerical calculation the percentage composition of inert and reacting particles in coal-dust and their total mass were changed for each simulation. We have determined the influence of the percentage composition of inert and reacting particles on burning characteristics of polydisperse coal-dust methane-air mixture. The results showed that the percent increase of volatile components in the mixture lead to the increase of total pressure in the volume. The value of total pressure decreases with the increasing of the inert components in the mixture. It has been determined that there is the extremism radius value of coarse particles by which the maximum pressure reaches the highest value.