Dancing with bubbles: Deterministic versus probabilistic bubble models in dense phase sand fluidized beds for biomass gasification

Abstract

This study addresses the need to model bubble flow in a fluidized bed using a probabilistic approach, which includes intrinsic bubble flow randomness. It is shown that the proposed probabilistic predictive model (PPM) overcomes the limitations of deterministic correlations, commonly used to describe bubble dynamics in high-density (above 2000 kg/m3) sand-beds of Type B particles of the Geldart classification. It is proven that a PPM can describe the relationship between bubble axial chord and bubble rise velocity using minimum and maximum behavioral bands. This probabilistic model, which applies to a wide range of operating conditions, as shown in the present study, can be considered applicable to single bubbles injected at incipient fluidization, as well as to bubbly beds with and without loaded biomass pellets.