Computational fluid dynamics simulation and parametric study of coal gasification in a circulating fluidized bed reactor

Abstract

AbstractA computational fluid dynamics model based on the Eulerian–Eulerian multiphase framework was implemented to simulate the coal gasification processes in a circulating fluidized bed gasifier. The standard k–ε turbulence model is used for gas phase, and the solid phases are modeled with kinetic theory of granular flow. A lumped chemical reaction model was compiled based on the chemical percolation devolatilization model and the METC Gasifier Advanced Simulation gasification model. The user‐defined functions are developed to calculate rates of chemical reactions and to recirculate solids from the riser exit to the solid recycle inlet. Sensitivity analysis was performed on char–steam gasification reaction to choose an appropriate kinetic rate in this study. The calculated gas composition out of the riser was first compared with experimental data; then, the flow fields such as solid volume fraction, solid velocity, and species profiles were analyzed, indicating that the model gave reasonable predictions. Furthermore, the effects of the operating temperature, the steam/coal ratio, and the air/coal ratio on the exiting gas composition were numerically studied, and the predicted trends vs these parameters are reasonable and consistent with the findings in the literature, which shows the applicability of the Eulerian multiphase model to simulate coal gasification processes in circulating fluidized bed gasifiers. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.