Characterization of countercurrent liquid-upward and solid-downward fluidized system

• Published in: Particuology 2022-11, Vol.70, p.95-105
• Main Authors: Zhang, Enming, Ma, Keying, Shao, Yuanyuan, Zhu, Jesse, Nan, Tian
• Format: Article
• Language: English
• Subjects: Countercurrent fluidization; Flooding; Pressure drop; Richardson–Zaki equation; Solids holdup
• ISSN: 1674-2001; 2210-4291
• DOI: 10.1016/j.partic.2022.01.009

[Display omitted] •Variations of pressure drop with the operating conditions were investigated in detail.•Two novel methods were proposed to identify flooding velocity in a countercurrent liquid–solid fluidized bed.•Effects of device structure and operating conditions on solids holdup were studied.•A modified Richardson–Zaki equation was established to predict the solids holdup. Acting as an operating mode of fluidization, the flow characteristics of a countercurrent liquid–solid fluidized bed (CCLSFB) were experimentally investigated using a Plexiglas column of 1.5 m in height. Countercurrent liquid-upward and solid-downward fluidization was achieved under a limited solid flowrate before flooding occurred. The “flooding” phenomena and the flooding velocity were identified by measuring the variations in pressure drop in the axial direction of the column. Two different methods were used to quantify the flooding point that led to the instability of the system. Axial solids holdup profiles were also obtained from the pressure drop data along the column and the influences of device structure and operating conditions on the solids holdup were also studied. Seven types of particles with different diameters and densities were used. An agreement was found between the experimental results and the mathematic prediction derived from the Richardson–Zaki equation on the data of the solids holdup.