Numerical study on fluidization behaviors and heat transfer characteristics of carbonized slag in a fluidized bed with liquid addition

Abstract

Fluidized bed technology is pivotal in chemical engineering, metallurgy, and energy, facilitating efficient heat and mass transfer. This research investigates the particle dynamics and thermal transport of carbonized slag in a fluidized bed with liquid addition, a process involving complex gas-liquid-solid interactions under varying operating conditions. A two-dimensional computational fluid dynamics model is developed, incorporating three interphase resistance models and an evaporation model. Simulation results show good agreement with experimental data regarding fluidization indices and particle motion trajectories, validating the reliability of the simulation methodology. The findings show a bimodal solid volume fraction distribution at a bed height of 45 mm, with high concentration in the transition region. The particle dynamics dominate structural evolution, causing fluctuations at gas-solid interfaces. Increased gas velocity reduces temperature drops by 12–16 %, while higher temperatures enhance evaporation efficiency by 47 %. The non-monotonic thermal variations occur with increasing height-to-diameter ratios due to coupled phase-change and convective heat transfer. These findings offer valuable insight for the theoretical optimization of fluidized bed reactors and the fluidization operation processes of carbonized slag.