Lagrangian Simulation of a CLC Reactor

This chapter describes the Lagrangian particle-based approach coupled with CFD simulation of the fluid phase known as the coupled CFD-DEM (discrete element method) model to simulate the gas-solid flow and reactions in a pseudo-2D spouted fluidized bed reactor. The first simulation described here was conducted using Fe2O3 as the bed material. Poor fluidization behavior was observed because of the large particle density of Fe2O3. A lighter bed material consisting of 60 wt.% Fe2O3 supported on MgAl2O4 was then considered for comparison with pure Fe2O3. The results of the simulation using the lighter material showed significant improvement. However, one deficiency that was noted in the simulation of the spouted fluidized bed in terms of the fluidization performance of the system was that after the particles settled down in the bed after the first bubble, subsequent bubbles formed in the fuel reactor lacked the energy required to reach the top of the reactor and into the cyclone. Since the spouted bed configuration has been proposed for its advantages when solid coal is used as fuel, the reaction mechanisms with coal were investigated by considering a pseudo-coal injection representing the gaseous products after the devolatilization and gasification of the solid coal, and the results show great promise.