CFD Modelling Gas-Solid Flows in CFB/FCC Riser Reactors: Simulation Using Kinetic Theory of Granular Flow (KTGF) in a Fully Developed Flow Situation

This study presents the simulation of gas-solid hydrodynamics and flow behaviour in a riser in an FCC riser circulating fluidised bed (CFB) reactor using the Eulerian-Eulerian two-fluid modelling approach, incorporating a kinetic theory constitutive model for dilute assemblies of FCC particulate solid. The interaction between gas and particles was modelled using particle interphase transfer model and Gidaspow drag model on a proprietary computational fluid dynamics (CFD) code ANSYS CFX, using turbulent k-e model. The interaction between gas and solid particles was modelled using particle interphase momentum transfer model with Miller-Gidaspow drag model on the commercial code. The simulation was run on steady state and then on transient conditions. Computational fluid dynamics (CFD) usefulness for FCC riser reactor is reaching an advanced stage in solving real life problems. It is a good practise to run a time-average comparison for solid velocities and concentrations to measure fluxes and densities along the riser axes. However, the hydrodynamic behaviour of gas-solid flow in riser was successfully compared with published experimental data of a CFB/FCC riser of length 15.1m and 0.1 m diameter. The overall flow patterns within the riser bed were predicted well by the model. For volume fraction around 2-3%, which is the average particle concentration in the riser system, the computed solid-holdup agrees with the experimental measurements. The predicted results and analysis will be useful for further modelling of industrial FCC riser reactors.