Prediction of minimum fluidization velocity for binary mixtures of biomass and inert particles

Fluidization of biomass particles is an important process in the gasification, pyrolysis and combustion of biomass for the extraction of energy. In this study, experiments were carried out in a 14.5 cm internal diameter cold flow fluidization bed to determine the minimum fluidization velocities with air as fluidizing medium. Studies on the fluidization of biomass particles (corn cobs and walnut shells), inert particles (sand, glass beads, and alumina), and biomass and sand mixtures were performed. Various weight percentages of biomass particles in the biomass and sand mixture were chosen in the range of 0–100%. On the of basis of experimental data from both present work and those found in the literature, new correlations were developed to predict the minimum fluidization velocity for inert particles, biomass particles, and biomass and sand mixtures in terms of biomass weight percentage. It was found that our results for the inert particles and biomass particles are in good agreements with those found in the literature. It was further found that the minimum fluidization velocity based Reynolds number for the mixture of biomass and inert particles depends on the weight percentage of biomass particles other than the Archimedes number. Based on our experiment results, we proposed a new correlation which includes the weight percentage as an additional variable for the mixture of biomass and sand particles. This new correlation can also be applied to inert particles or biomass particles by setting the weight percentage to be 0 or 100% accordingly.