Prediction of void fraction and minimum fluidization velocity of a binary mixture of particles: Bed material and fuel particles

Abstract

For operational control and design of a fluidized bed reactor containing different types of solid particles, the bed void fraction and minimum fluidization velocity are vital parameters. This paper demonstrates a method for predicting the void fraction and minimum fluidization velocity of different binary mixtures of particles with improved accuracy. A new model for predicting the void fraction is presented. This model is non-linear and continuous, and it is developed by introducing a packing factor and establishing a mass balance between the solid phases in the packing environment. The results show that the model can accurately predict the void fraction of a binary mixture where the particles are well mixed, partially mixed or segregated. Using this void fraction model and the Ergun equation of pressure drop, the minimum fluidization velocity can be predicted with mean errors of 15.2% for a mixture of two inert materials and 7.0% for a mixture of biomass and inert particles.