Three-dimensional full -loop numerical simulation of co -combustion of coal and refuse derived fuel in a pilot -scale circulating fluidized bed boiler

A multiphase particle-in-cell (MP-PIC) method is used to simulate the co-combustion process of coal and refuse derived fuel (RDF) in a full-loop three-dimensional (3D) pilot-scale circulating fluidized bed (CFB) based on the Eulerian-Lagrangian framework. The heat transfer, pyrolysis of volatiles, combustion of gaseous fuel and char, and generation of gaseous pollutants are all considered. The independence tests of grid size and computational parcel number are carried out. The predicted temperature profile and gas pollutants emission concentration are compared with experimental data and consistent results have been achieved. After model verification and validation, the gas-solid flow characteristic, solid holdup distribution, pressure distribution, temperature distribution of two phases and gas composition profile in the CFB are studied. The influences of bed temperature and primary air ratio on gas pollutants emission are then explored. The results indicate that the emission of NO, SO2 and HCl increases while the emission of N2O and CO decreases as the bed temperature increases, and the emission of N2O, NO and SO2 increases while the emission of CO decreases as the primary air ratio increases. © 2020 Elsevier Ltd