A bubbling fluidization model using kinetic theory of granular flow

TLDR

Detailed knowledge of solids circulation, bubble motion, and porosity oscillations is needed to understand tube erosion in fluidized bed combustors. A predictive two‑phase flow model was derived from the Boltzmann equation, generalizing Jackson’s Navier‑Stokes formulation by computing solids viscosities and stresses through a fluctuating energy equation for the particulate phase. Model predictions match measured time‑averaged and instantaneous porosities in two‑dimensional fluidized beds and correctly predict observed flow patterns and bubbles.

Abstract

Abstract Detailed knowledge of solids circulation, bubble motion, and frequencies of porosity oscillations is needed for a better understanding of tube erosion in fluidized bed combustors. A predictive two‐phase flow model was derived starting with the Boltzman equation for velocity distribution of particles. The model is a generalization of the Navier‐Stokes equations of the type proposed by R. Jackson, except that the solids viscosities and stresses are computed by simultaneously solving a fluctuating energy equation for the particulate phase. The model predictions agree with time‐averaged and instantaneous porosities measured in two‐dimensional fluidized beds. Observed flow patterns and bubbles were also predicted.