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

• Published in: Chemical engineering science 2012-12, Vol.84, p.437-448
• Main Authors: Qi, Maozhan, Zhu, Jesse, Barghi, Shahzad
• Format: Article
• Language: English
• Subjects: air; Applied sciences; Chemical engineering; Circulating; Circulating turbulent fluidized bed; Circulation; Cross-correlation; Dilution; Exact sciences and technology; Fluid dynamics; Fluid flow; Fluidization; fluidized beds; High solids flux; hydrodynamics; Hydrodynamics of contact apparatus; Local solids flux; Phase particle velocity; Phase slip particle velocity; Phases; Turbulence; Turbulent flow
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2012.08.047

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. ▸ A Divided Phase Cross-Correlation Method (DPCCM) is proposed. ▸ Particle velocities of dense and dilute phases are obtained using DPCCM. ▸ Gas–particle interaction dominates in the dilute phase. ▸ Particle–particle interaction dominates in the dense phases at low solids flux. ▸ Particle–particle and particle–backpressure interactions jointly dominate in the dense phases at high solids flux.