Numerical study of interaction of coal dust with premixed fuel-lean methane-air flames

Interaction of combustible particles with flames occurs in fire scenarios. In this study, numerical investigation of interaction of coal dust or micron-sized particles with lean premixed methane-air flames is presented. A two-dimensional axisymmetric domain is employed to simulate conical premixed flames from lab-scale Bunsen burner. A chemical kinetic mechanism having 25 species and 121 elementary reactions, temperature dependent thermo-physical properties, multi-component diffusion with Soret effect and radiation model accounting for gas and soot radiation are used. Discrete Phase Model (DPM) is used to simulate the transport of coal particles. Coal particles in varies size ranges and concentrations are injected into the premixed reactant mixture at equivalence ratio between 0.75 and 0.85. Multiple species from devolatilization of coal particles are considered to enter the gas-phase. Laminar flame speeds are predicted using numerical shadowgraphs and validated against the experimental data from literature. Injection of coal particles affects the laminar burning velocity and flame structure. The numerical model is able to predict the variation trends in the laminar flame speed data quite reasonably. A detailed analysis of injection of coal particles on the resultant flame dynamics are presented using the fields of temperature, flow, species, net reaction rate, heat release rate and DPM. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.