Modeling of pulverized coal combustion with non-gray gas radiation effects

Abstract

A numerical study for simulating a swirling pulverized coal combustion in axisymmetric geometry is carried out here by applying the weighted sum of gray gases model (WSGGM) approach with the discrete ordinate method (DOM) to model the radiative heat transfer equation. In the radiative transfer equation, the same polynomial equation and coefficients for weighting factors as those for gas are adopted for the coal/char particles as a function of partial pressure and particle temperature. The Eulerian balance equations for mass, momentum, energy, and species mass fractions are adopted with the standard k-epsilon turbulence model, whereas the Lagrangian approach is used for the particulate phase. The eddy-dissipation model is employed for the reaction rate for gaseous mixture, and the single-step first-order reaction model for the devolatilization process for coal. By comparing the numerical results with experimental ones, the radiation model used here is confirmed and found to provide sound alternative for simulating radiative characteristics.