Improved Models for Predicting Bubble Velocity, Bubble Frequency and Bed Expansion in a Bubbling Fluidized Bed

Abstract

An efficient design and operational control of a fluidized bed reactor relies on accurate prediction of bubble properties. This paper employs measurement of bed void fraction in determining the bubble velocity in a given bed. An analytical model is developed for bubble rise velocity, which shows that the rise velocity of a single bubble is proportional to the rate of change of the bubble-projected area. Based on the model for bubble rise velocity, a correlation for bubble velocity is obtained as given by Bubble frequency is also modelled and presented as , and bed expansion due to bubble flow in a larger particle bed (Ar ≥ 400) is modelled by . The three models have been validated against experimental data and the results show that the bubble velocity model has a better prediction accuracy than the existing models for Geldart B and D particles with prediction errors of 15.5% and 12.0%, respectively. The results also show that the proposed bed expansion model predicts better than the existing models in the literature.