On the dynamics of gas–solid flow in a pilot-scale CFB riser: an experimental analysis

Circulating fluidized beds (CFBs) are heterogeneous gas–solid reactors whose fluid dynamics are complex and poorly validated on a pilot scale. In this work, the dynamics of particle distribution were measured using Phase Doppler Anemometry (PDA) to provide quantitative data for understanding and modeling this phenomenology. The transverse fields of velocity, concentration, and diameter distribution at 17 radial points and three axial positions of the pilot-scale riser showed a persistent core-annulus structure, geometric influence causing azimuthal asymmetry and back-mixing, high velocity fluctuation near the wall, as well as radial and axial segregation of concentration and particle diameters in the riser. In the low-loading cases, particle velocity increased by more than 20% from the bottom to the top, while at the top centerline the densest case reached 28% above the superficial gas velocity; near-wall velocity fluctuations reached about 20% of the superficial gas velocity. The results provide a robust data set for validation of computational models and provide insights for optimized design on a larger scale.