Simulation and experimental verification of a hydrodynamic model for a dual fluidized Bed gasifier

We propose a revised 2-D energy-minimization multi-scale (EMMS) model based on a two-fluid model to perform the hydrodynamic character analysis of a pilot-scale full-loop dual fluidized bed gasifier (DFBG), which consists of a riser, a cyclone with a down-comer, a bubbling fluidized bed (BFB), and a loop-seal. The EMMS model is used to analyze the interaction force between the gas and solid phases in the DFBG. For comparison, OʹBrien & Syamlalʹs drag heterogeneous force coefficient correction is also analyzed. The instantaneous particle profiles are described by the calculated results. The local and overall flow characteristics are determined by the solids concentration under different fluidization conditions. The effects of the gas velocities in the riser and the recycle gas velocities in the U loop seal on the axial solids concentration and solids circulation profiles, as well as the flow heterogeneity in sub-zones of the riser are investigated. The numerical results are in good agreement with the experimental data, indicating that the EMMS model is appropriate to simulate the heterogeneous gas–solids two-phase flow in DFBG.