Combustion modeling of bituminous coal using turbulence- chemistry interactions for sustainable fuel

Abstract Studies in the computational fluid dynamics (CFD) context have made it possible in short duration, to deliver the insights into complex combustion processes involved in solid fuel combustion such as, pyrolysis /evaporation, de-volatilization, char combustion as well energy exchange between gases, particles, and burner walls. In this work, computational investigation has been performed on a fluid dynamically stabilized pilot-scale oxy-coal burner at standard thermodynamic conditions. Turbulent combustion modeling was carried out with turbulence chemistry interaction model using Finite Rate / Eddy Dissipation model along with other sub-models. More specifically, the concept of CO2 recirculating oxy-fuel combustion technology is utilized to achieve the stable flame and air-coal combustion like flame parameter especially the flame temperature. The radial profiles of combustion parameters were observed at radial lines located at different axial distances downstream of combustor inlet. Effects of varying turbulent mixing time scale or mean residence time is studied owing to its importance in optimizing fuel-oxidizer mixing and sub-sequent combustion process. It is observed that stable flame in air like oxy-coal combustion is achieved, and flame temperature of 1850 K have been noticed. Lower turbulent mixing scale or residence time caused higher flame temperature of 1950 K. CO2 recirculating oxy-coal combustion process can be optimized by aerodynamic control strategies for efficient mixing while keeping the NOx emissions in control. Because of N2 replacement with CO2 in the oxy-fuel combustion environment, the dissociation of N2 species even at higher temperature can be avoided.