Liquid-solid fluidization

The expression gas-liquid fluidization, as defined in Section III,B,3, is used for operations in which momentum is transferred to suspended solid particles by cocurrent gas and liquid flow. It may be noted that the expression gas-liquid-solid fluidization has been used for bubble-column slurry reactors (K3) with zero net liquid flow (of the type described in Sections III,B,1 and 1II,V,C). The expression gas-liquid fluidization has also been used for dispersed gas-liquid systems with no solid particles present. 

Recent research development of hydrodynamics and heat and mass transfer in inverse and circulating three-phase fluidized beds for waste water treatment is summarized. The three-phase (gas-liquid-solid) fluidized bed can be utilized for catalytic and photo-catalytic gas-liquid reactions such as chemical, biochemical, biofilm and electrode reactions. For the more effective treatment of wastewater, recently, new processing modes such as the inverse and circulation fluidization have been developed and adopted to circumvent the conventional three-phase fluidized bed reactors [1-6]. 

L. S. Fan, Gas-Liquid-Solid Fluidization Engineering, Butterworth, Boston, MA(1989) 368. 

Bavarian and Fan [3, 4] reported a similar phenomenon occurring in a three-phase fluidized bed. In their case, the hydraulic transport of a packed bed occurred at the start-up of a gas-liquid-solid fluidized bed. Although the cause was different from the case reported in the present study, similar phenomena were observed in both cases. 

Fan, L. S., Hwang, S. J., and Matsuura, A., Some Remarks on Hydrodynamic Behavior of a Draft Tube Gas-Liquid-Solid Fluidized Bed, AIChE Symp. Ser., 80(234) 91 (1984)... 

Fan, L. S., Fujie, K., Long, T. R., and Tang, W. T., Characteristics of Draft Tube Gas-Liquid-Solid Fluidized-Bed Bioreactor with Immobilized Living Cells for Phenol Degradation, Biotechnol. Bioeng., 30 498 (1987b)... 

III. System 1 Flow Dynamics of Gas-Liquid-Solid Fluidized Beds... 

C. Modeling the Motion and Collision Dynamics of Solid Particles in Gas-Liquid-Solid Fluidization... 

In system 1, the 3-D dynamic bubbling phenomena in a gas liquid bubble column and a gas liquid solid fluidized bed are simulated using the level-set method coupled with an SGS model for liquid turbulence. The computational scheme in this study captures the complex topological changes related to the bubble deformation, coalescence, and breakup in bubbling flows. In system 2, the hydrodynamics and heat-transfer phenomena of liquid droplets impacting upon a hot flat surface and particle are analyzed based on 3-D level-set method and IBM with consideration of the film-boiling behavior. The heat transfers in... 

Fan, L. S., Gas-Liquid-Solids Fluidization Engineering . Butterworths, Stoneham, MA (1989). Fan, L. -S., and Tsuchiya, K., Bubble Wake Dynamics in Liquid and Liquid-Solid Suspensions . Butterworth-Heinemann, Stoneham, MA (1990). 

Reactors, 14 89. See also Autoclaves airlift, 15 708-709, 713-714 boiling water, 17 578-582 bubble column, 15 708-709 deep shaft, 15 713, 714 draft-tube sparged concentric draft-tube airlift, 15 712-713 fast-breeder, 17 585-588 gas-liquid-solid fluidized bed,... 

In a similar way, a high liquid velocity will cause hydraulic conveying in a liquid-solid fluidized bed. 

Particulate fluidization, where the fluidizing medium is usually a liquid, is characterised by a smooth expansion of fhe bed. Liquid-solid fluidized beds are used in continuous crystallisers, as bioreactors in which immobilised enzyme beads are fluidized by the reactant solution and in physical operations such as the washing and preparation of vegetables. The empirical Richardson-Zaki equation (Richardson... 

Epstein, N., Applications of liquid-solid fluidization, bit.. Chem. Reactor Eng., 1 (2003) 1-16. 

The literature on the use of the liquid-solid fluidized bed as a biochemical reactor is vast much of it is devoted to what may be generally termed fermentation reactions. The principle of the fluidized bed bioreactor, whether based on liquid-solid or on gas-solid fluidization, is... 

Other applications of liquid-solid fluidized beds that have been suggested or put into practice include the leaching of vegetable oils from seeds (Epsfein, 2003), fhe freeze concentration of solutions (Rios et al., 1985) and osmotic drying (Marouze et al., 2001). Fluidization is also the basis of fhe hydraulic fransport of vegetables (McKay et al., 1987). Three-phase fluidized beds have been employed for the fermentation of cocoa beans (Jacquef et al, 1981 Rios et al, 1985). 

It has not been possible to cover all aspects of the principles of fluidization. A number of comprehensive texts on fluidized bed behaviour are available and inevitably I have drawn heavily on these. The reader who wishes to go into greater depth about the fundamental mechanisms at work in fluidized beds should consult those works by Davidson and Harrison (1971), Botterill (1975), Davidson, Clift and Harrison (1985), Kunii and Levenspiel (1991) and more recently Gibilaro (2001). Full references can be found at the end of Chapter 1. In addition, I have concentrated on gas-solid fluidized beds somewhat to the exclusion of liquid-solid fluidization although an indication of how particulate fluidization can be applied to biochemical reactors is given in Chapter 7. 

Part One of the book is a description of fluidized bed behaviour and covers the theory necessary to understand the applications which follow. Chapter 1 is a description of the characteristics of both gas-solid and liquid-solid fluidized beds, concentrating especially upon the predication of minimum fluidizing velocity. Chapter 2 covers the all-important topics of heat transfer, mass transfer and particle mixing which underpin almost all the applications of fluidization, which are treated in Part Two. 

An equation similar to that of Wen and Yu that has been proposed for the liquid-solid fluidization is that of Limas-Ballesteros (Lee et al., 2005) ... 

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