Development of boundary transfer method in simulation of gas–solid turbulent flow of a riser

Abstract Computational fluid dynamics (CFD) is used to simulate the behavior of two phase gas solid in a fluid catalytic cracking (FCC) riser. Gas and particle phases are considered as separate fully interpenetrating continuous media within each control volume. Each phase described in terms of its own separate mass and momentum conservation equations. Simple k–epsilon (kg–ϵg) turbulence model is used for the gas phase and the solid phase is handled with the kinetic theory of granular flows. Source terms are used to account for the influence of hydrodynamic drag on the production, dissipation and exchange of turbulent kinetic energy between the phases. For the particles partial slip condition is considered at the wall. The non-equilibrium effects near the wall including separation, reattachment and stagnation are mainly occurs at inlets, outlets and upper’s lid of risers. In this study, the boundary transfer method (BTM) for coupled gas–solid equations developed. This method projects the wall boundary conditions into the body of fluid. Furthermore, simulation results compared with available experimental data of FCC riser. Using developed BTM, which considers the non-equilibrium effects, has major improvement on prediction of gas and in consequence solid flow pattern in the riser.

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