Flow regimes and transitions in an ultra-high temperature gas-solid fluidized bed

Gas-solid fluidized bed reactors are widely used in industrial operations and thus have led to a significant amount of fundamental research over decades. For better design and operation of fluidized bed systems, it is essential to understand the fluidization regime and the related transition conditions. Dr. John R. Grace, a prominent figure and pioneer in fluidization science and technology, has made significant contributions to understanding fluidized bed systems, including fluidization regimes and their transitions. This study is a tribute to his extraordinary legacy, focusing on investigations of fluidization regimes and transitions in a laboratory-scale gas-fluidized bed operating from ambient to 1600 °C. The results indicate that the fluidization regime transitions follow three distinct pathways across different temperature ranges: below 300 °C, from 300 to 1400 °C, and above 1400 °C. These distinctive transitions arise as a result of the varying significances of hydrodynamic and interparticle forces in the fluidized bed of particles investigated.