Unsteady Numerical Simulation of Pulverized Coal Combustion in a Strong Swirling Flow

Abstract

Large-eddy simulation (LES) is applied to a pulverized coal combustion field in a combustion test furnace with a practical advanced low NO_x burner called CI-α, and its validity is investigated by comparing with the experiment. The motion of coal particles is calculated by the Lagrangian method with a parcel model. In the coal combustion modeling, three chemical processes are considered, namely devolatilization, char combustion and gaseous combustion. The direct closure SSFRRM (scale similarity filtered reaction rate model) is used as a turbulent combustion model. The results show that a swirling recirculation flow is formed in the central region close to the burner and its size and strength dynamically change with time. The predicted distributions of gaseous temperature and oxygen concentration are in general agreement with the experiment.