CFD modeling of pulverized coal combustion in an industrial burner

The accurate prediction of pulverized coal combustion in industrial application still remains a great challenge. This is mainly due to the lack of high quality experimental data acquired during the operation of industrial plants. This work describes the CFD model used in order to numerically simulate the pulverized coal combustion of a full scale, swirl stabilized, aerodynamically staged, industrial burner. In particular, two different combinations of devolatilization and char burnout models were investigated comparing the numerical results with available experimental data obtained during a burner test carried out, in full-scale configuration, in a 50 MWth, fully instrumented, test rig. In order to avoid any unrealistic assumption on pulverized coal distribution at the burner inlet, the entire primary air duct for pulverized coal transportation has been considered. The main flow is computed solving the steady, incompressible, three-dimensional, Reynolds Averaged Navier-Stokes (RANS) equations, whereas the pulverized coal is simulated as a reacting discrete second phase in a Lagrangian frame of reference, computing the trajectories of the discrete phase entities, as well as heat and mass transfer. The numerical analysis confirms the very good burner performance obtained during the tests with a very low percentage of fixed carbon left in the ashes.