(617e) CFD Modeling of a Dual Fluidized-Bed System Using an Eulerian-Lagrangian Approach

A three-dimensional computational fluid dynamics (CFD) model was established to simulate a pilot (6 tons/day, 1 MWth) dual fluidized-bed system. In the CFD model the momentum equation was coupled with the mass and energy transport equations to simulate mass and energy transfer in the dual fluidized-bed system, which includes a gasifier, a combustor, a cyclone separator, and a loop-seal. An Eulerian-Lagrangian approach was applied to describe the interactions between the particulate and gas phases. Heterogeneous particle-gas and homogeneous gas-phase reaction kinetics were developed to simulate char pyrolysis, combustion, and gasification, water gas-shift reaction, steam reforming reaction, and oxidation of CO, H₂, and CH₄ in the dual fluidized-bed system. The CFD model simulated the full-loop of dual fluidized-bed system (a gasifier, a combustor, a cyclone separator, and a loop-seal). It was utilized to predict particle circulation, syngas composition, and temperature distributions in the dual fluidized-bed or gasifier-combustor gasification system.