CFD Modeling of Pulverized Coal Combustion Using Relax to Chemical Equilibrium Model With Turbulence-Chemistry Interaction

Abstract

Abstract A comprehensive numerical investigation of 2.4 MW IFRF swirl-stabilized coal furnace is conducted. A novel Relax to Chemical Equilibrium (RTCE) model with turbulence-chemistry interaction is used for the gas-phase combustion and the results are compared with the standard Eddy Break-Up (EBU) model. In the RTCE model, the species compositions are relaxed towards the local chemical equilibrium at a characteristic time scale determined by the local flow and turbulence. The turbulence-chemistry interaction is treated using the Eddy Dissipation Concept (EDC) model. The simulation uses a Lagrangian-Eulerian framework to treat the particle transport and the fluid-particle interactions. In all, fifteen species have been included in the RTCE model. For coal particles, a one-step devolatilization, first-order char oxidation, particle porosity, and particle radiation models are employed. The NOx emissions model includes both thermal and fuel NOx pathways. It was found that RTCE model performs well in predicting the overall temperature distribution in the IFRF coal furnace. The predicted temperature, NOx and CO at the outlet match very well with the experimental data, showing marked improvement over the EBU model. The overall NOx profile is also predicted better by the RTCE model.