Validation of the CFD model for prediction of flow behaviour in fluidized bed reactors

Abstract

The aim of this study is to develop a robust CFD model for predicting fluid dynamics in a gasification reactor. Experimental tests are performed. A cylindrical bed with pressure sensors is used in the experimental study. A series of simulations are performed using the commercial CFD tool ANSYS Fluent 12.1. A multi-fluid Eulerian model incorporating the kinetic theory of granular flow is applied in the simulations. Fluidized bed reactors in biomass gasification processes use steam as a fluidizing gas. High temperature makes it difficult to study the flow behaviour under the operating conditions. A cold flow model is constructed to study the fluid dynamics. Air at ambient conditions is used as the fluidizing gas for the cold model. The density and viscosity variation between air at ambient temperature and steam at high temperature results in different flow behaviour. The CFD model is developed to also be able to predict the flow behaviour of steam fluidized beds. Computational minimum fluidization velocity, bed expansion ratio pressure drop and pressure standard deviation agree well with experimental measurements. A computational model has been developed and validated against experimental data. The validated CFD-model can be useful in the study of flow behaviour of high temperature steam fluidized gasification reactors. © 2012 WIT Press.