CPFD simulation of a dual fluidized bed cold flow model

Abstract

The present work was carried out to simulate a cold flow model of a biomass gasification plant. The fluid dynamical behavior depends heavily on the particles’ properties like the particle size distribution (PSD). For the simulation an Eulerian-Lagrangian approach, in particular by the multi-phase particle in cell (MP-PIC) method, was used to simulate particles with a defined PSD. Therefore, Barracuda VR, a software tool with an implemented MP-PIC method specifically designed for CPFD (computational particle fluid dynamics) simulations, was the software of choice. The simulation results were verified with data of previously conducted experiments on a physical cold flow model. The cold flow model was operated with air and bronze particles. The simulations were conducted with different drag laws: an energyminimization multi-scale (EMMS) approach, a blended Wen-Yu and Ergun (WYE) drag law, and a drag law of Ganser. Furthermore, a focus was set onto the normal particle stress (PS value variation), which is significant in close-packed regions, and the loop seals’ fluidization rate was varied to influence the particle circulation rate. The settings of the simulation were optimized, flooding behavior did not occur in advanced simulations, and the simulations reached a stable steady state behavior. The Ganser drag law combined with an adjusted PS value with (PS = 30 Pa) or without (PS = 50 Pa) increased loop seal fluidization rates provided the best simulation results.