Computational modeling of pulverized coal combustion processes in tangentially fired furnaces

In this work, an Eulerian/Lagrangian approach has been employed to investig ate numerically flow characteristics, heat transfer and combustion processe s in a tangentially fired furnace. A new method of cell face velocity inter polation for non-staggered grid system is employed to avoid pressure oscill ation. Grid-independence tests have been conducted. To avoid pseudo-diffusi on that is significant in modeling tangentially fired furnaces, some attemp ts have been made at improving the finite-difference scheme. The standard k -epsilon model performs well in predicting Rows without swirling or without sharp change within the calculated region. But for tangentially fired boil er furnaces, where swirling flow is very marked, we must resort to other mo re valid, more efficient turbulent models to gain accuracy. Tn this paper, we try to use RNG k-epsilon model as an alternative to the standard k-epsil on model. Comparisons have been made between standard k-epsilon and RNG k-e psilon models. Some new developments on turbulent diffusion of particles ar e taken into account for improving computational accuracy, and probability error is also discussed. Finally, temperature deviation is studied numerica lly so as to gain deeper insight into tangentially fired furnaces. (C) 2001 Elsevier Science B.V. All rights reserved.