A computational fluid dynamics study on the flow field in a liquid–solid circulating fluidized bed riser

Abstract

A detailed study on the hydrodynamics of liquid–solid circulating fluidized bed (LSCFB) reactors is crucial in the efficient design and scale-up of these reactors. In this paper, an axisymmetric CFD model is developed to simulate the flow field in a LSCFB riser. The model is based on Eulerian–Eulerian approach incorporating the kinetic theory of granular flow. The predicted results agree well with our earlier experimental data. Furthermore, it is found that the dispersed k–ε multiphase turbulence model is more accurate and computationally efficient than other k–ε multiphase turbulence models. Also, the model predicts the residence time of both liquid and solid phases in the riser by using a Pulse technique. Finally, the proposed CFD model is used to investigate the effects of the liquid stream velocity and the solids circulation rate on the performance of the LSCFB. It is demonstrated that the proposed CFD model can be a robust tool for the scale-up and design of industrial LSCFB reactors.