(83d) Multiphase Particle in Cell Simulation Study of Ammonia Co-Combustion in a Circulating Fluidized Bed Combustor

In this study, a lab-scale circulating fluidized bed (CFB) combustor established by three dimensional Eulerian-Lagrangian model was used to simulate the co-combustion behavior of ammonia and coal. The 3D CFB model consists of riser, cyclone, loop-seal and diplegs. On the basis of the multiphase particle-in-cell (MP-PIC) scheme, the gas phase is modeled by a large eddy simulation (LES) approach and the solid phase by discrete particle method. Various reaction kinetics including devolatilization, combustion of char, volatiles and ammonia, formation and retention of acid gas, and production and reduction of NO and N2O are simultaneously considered. The gas-solid behaviors of the CFB combustor and co-combustion characteristics are obtained with the ammonia co-combustion ratios from 0 to 40%. Numerical results reveal that a fast fluidization regime takes place in the chamber region, while a bubbling fluidization regime appears in the loop-seal. Though N2 input increased with increasing ammonia input, NOx concentration in flue gas was stabilized due to the decrease of thermal NOx formation.