Detailed Modelling of a Swirling Coal Flame

Abstract

A mathematical model for the swirling coal flame is presented and applied in the simulation of a 2 MWt furnace (1FRF MMF5-2). The model accounts in a self-consistent way for the effects of turbulent fluid mechanics, gaseous turbulent combustion, particle dispersion, coal devolatization, heterogeneous char reaction and thermal radiation. The description of species transport and combustion chemistry is based on the mixture fraction/probability density function approach. Effects of thermal radiation are accounted for by means of the P-l (differentia]) model. Numerical solution is achieved using a collocated control volume finite difference approach and a non-orthogonal curvilinear grid allows representation of the tulip shaped burner quarl. The flow field predicted by the model is shown to be in a good agreement with observations. The agreement between predicted and observed temperature profiles is generally good although the observed inside quarl temperatures are higher than those predicted. Predicted species concentrations compare well with measured values.

Keywords:

• Coal combustion
• mathematical model
• probability density function (PDF)
• equilibrium chemistry