Particle velocity and flux distribution in a high solids concentration circulating turbulent fluidized bed

Abstract

Hydrodynamics of gas–solid flow were experimentally studied in depth in a Circulating Turbulent Fluidized Bed (CTFB) using FCC particles of 76 μm in a wide range of air velocities and solids circulation rates. Instantaneous local solids holdups were acquired with dual channel optical fibre probes. Through cross-correlating the sub-signals of the dilute and dense phases, separated from the measured solids holdup data, a Divided Phase Cross-Correlation Method (DPCCM) was proposed and was successfully used to obtain the distributions of particle velocity and solids flux of the dense and dilute phases. The upward particle velocity of the dilute phase increased with increasing air velocity and did not change significantly with solids circulation rate, while one of the dense phase increased proportionally with increasing solids circulation rate and hardly changed with increasing air velocity. The results also demonstrated that gas–particle interaction dominated in the dilute phase, while particle–particle interaction dominated in the dense phases at low solids circulation rate. Particle–particle and back–pressure interactions dominated in the dense phase at high solids circulation rates.