Hydrodynamics of a gas‐liquid‐solid three phase circulating fluidized bed

Abstract

The hydrodynamics of a gas-liquid-solid circulating fluidsized bed was investigated. A new regime, the three phase circulating fluidization regime, was discovered for the first time. The characteristics of this regime were compared with that of the conventional fluidization regime and the transport regime. The particle circulation rate and the gas and solids holdups in circulating fluidization regime were studied.On a ttudit I'hydrodynamique d'un lit fluidid circulant gaz-liquide-solide. Un nouveau r6gime, le d g h e de fluidisation circulant triphasique, a t t t dkouvert pour la premikre fois. Ses caractkristiques sont cornparks h celles du rtgime de fluidisation classique et du rtgime de transport. On a thidit la vitesse de circulation des particules et les retentions de gaz et de solides en rCgime de fluidisation circulant.

Enhancement of Gas Holdup and Oxygen Transfer in Three-Phase Circulating Fluidized-Bed Bioreactors with Swirling Flow

“…It can be noted that the value of ε G increases considerably by injecting the swirling liquid flow. Actually, the values of ε G from this study show somewhat higher than those of other previous studies without swirling liquid flow (Liang et al, 1995;Wang et al, 2001;Son et al, 2007). Effects of swirling liquid ratio (R S ) on the gas holdup can be seen in Figures 3 and 4.…”

“…It has been understood that the turbulence intensity in the riser could increase with increasing particle size in a given operating conditions, which consequently results in an increase in the bubble breaking and thus decrease of bubble size and increase of bubble residence time in the riser. Therefore, the bubble holdup could increase with increasing the size of fluidized solid particles (Liang et al, 1995;Zhu et al, 2000;Kim and Kang, 2006).…”

Hydrodynamics and Mass Transfer in Gas‐Liquid‐Solid Circulating Fluidized Beds

“…Gas-liquid-solid circulating fluidized beds (GLSCFB), on the other hand, have quite different flow structures to the conventional threephase fluidized beds. The reported results [6] show that the phase holdups in a GLSCFB distribute uniformly along the bed height but non-uniformly in the radial direction. Similar results were also obtained in this work (as shown in the ªResults and Discussionº).…”

“…In comparison with conventional three-phase fluidized beds, the GLSCFBs have the advantages of plug flow, smaller bubbles, and better interfacial contact. Unlike the conventional three-phase fluidized beds, the GLSCFBs show a non-uniform distribution of solid particles and gas bubbles [6]. Due to their different hydrodynamic characteristics, the mass transfer results obtained in the conventional three-phase fluidized beds may not be directly applied to the GLSCFBs.…”

Effects of Operating Variables on the Solid Circulation Rate in a Three-phase Circulating Fluidized Bed

“…Several investigators, therefore, have studied three-phase circulating fluidized beds. Individual phase holdup, liquid dispersion and mixing, flow regime, bubble properties, heat and mass transfer coefficients have been investigated to understand the system, in order to employ it in various kinds of industries [6][7][8][9][10][11][12]. However, most of the previous studies have their attention on the phenomena in the riser without any consideration on the control of solid circulation rate, which is one of the important factors in determining the characteristics and performance of three-phase circulating fluidized beds.…”