In this work, an Eulerian/Lagrangian approach has been employed to investigate numerically the how characteristics, heat transfer and combustion in a tangentially fired furnace. The RNG (Re-normalization group) k-epsilon model and a new method for cell face velocity interpolation based on a non-staggered grid system are employed. To avoid pseudo-diffusion that is significant in modeling tangentially fired furnaces, attempts are made at improving the differential volume scheme. Some new developments on turbulent diffusion of particles are also taken into account. Thus, computational, accuracy is improved substantially.