Two-phase suspension

Pressure Drop. The pressure drop across a two-phase suspension is composed of various terms, such as static head, acceleration, and friction losses for both gas and soflds. For most dense fluid-bed appHcations, outside of entrance or exit regimes where the acceleration pressure drop is appreciable, the pressure drop simply results from the static head of soflds. Therefore, the weight of soflds ia the bed divided by the height of soflds gives the apparent density of the fluidized bed, ie... 

Beaded polymeric support, whether polystyrene-divinylbenzene, polymethacrylate, or polyvinyl alcohol, is conventionally produced by different variations of a two-phase suspension polymerization process, in which liquid microdroplets are converted to the corresponding solid microbeads (1). 

Beaded polymeric supports are produced by a two-phase suspension polymerization in which microdrops of a monomer solution are directly converted to the corresponding microbeads. The size of a microdroplet is usually determined by a number of interrelated manufacturing parameters, which include the reactor design, the rate of stirring, the ratio of the monomer phase to water, the viscosity of both phases, and the type and concentration of the droplet stabilizer. 

Two-phase suspension systems produce beaded products with broader particle-size distribution (e.g., 1-50 /rm). The microspherical particles usually need to be classified repeatedly to reduce the particle-size distribution in order to improve the resolution and efficiency in the separation for use in chromatography. The actual classification process depends on the size range involved, the nature of the beaded product, and its intended applications. Relatively large (>50 /rm) and mechanically stable particles can be sieved easily in the dry state, whereas small particles are processed more conveniently in the wet state. For very fine particles (<20 /rm), classification is accomplished by wet sedimentation, countflow setting, countflow centrifugation, or air classification. 

Lin LD, Wu JY. (2002) Enhancement of shikonin production in single- and two-phase suspension cultures of Lithospermum erythrorhizon cells using low-energy ultrasound. Biotechnol Bioeng 78 81-88. 

Grace, J. R. (1986). Contacting Modes and Behavior Classification of Gas-Solid and Other Two-Phase Suspensions. Can. J. Chem. Eng., 64, 353. 

The polymeric adsorbents are usually prepared by variations of two-phase suspension processes. These refer to systems where microdroplets of monomers and solvent are converted into solid beads upon polymerisation. In the case where the monomers are not water soluble, as in the case of styrene-based polymers and many methacrylate-based polymers, the monomers, a solvent and a droplet stabiliser are suspended as droplets by stirring in water and then polymerised (o/w suspension polymerisation). The particle size and dispersity can be influenced by the stirring speed and the type of stabiliser. So far, only a few examples of the preparation of imprinted polymers in bead format have been described [4-8] and these are thoroughly reviewed in Chapter 12. In non-covalent imprinting, the main limitation to the use of these techniques is that the imprinting method often requires the use of polar partly water soluble monomers or templates in combination with less polar water insoluble components. Use of the o/w suspension method... 

Impinging streams [73] is a unique and multipurpose configuration of a two-phase suspension for intensifying heat and mass transfer processes in the following heterogeneous systems gas-solid, gas-liquid, liquid-liquid and solid-liquid. 

Drew and Wallis [37] (p 61) examined the forces on spheres in two-phase suspensions based on theoretical analyzes. Their result included lift forces that give rise to a net transverse force on particle swarms if the group of spheres are translating and rotating as a unit. Note that this force is different from... 

Langlois WE (1964) Slow Viscous Flow. Macmillan, New York Laux H (1998) Modeling of dilute and dense dispersed fluid-particle flow. Dr Ing Thesis, Norwegian University of Science and Technology, Trondheim, Norway Lawler MT, Lu P-C (1971) The role of lift in radial migration of particles in a pipe flow. In Zandi 1 (ed) Advances in Solid-Liquid Flow in Pipes and its Apphcations. Pergamon Press, Oxford, Chap 3, pp. 39-57 Lee SL (1987) Particle drag in a dilute turbulent two-phase suspension flow. Int J Multiphase Flow 13(2) 247-256... 

Lee SL (1987) A unified theory on particle transport in turbulent dilute two-phase suspension flow-11. Int J Multiphase Flow 13(1) 137-144 Lee SL, Borner T (1987) Fluid flow structure in a dilute turbulent two-phase suspension flow in a vertical pipe. Int J Multiphase Flow 13(2) 233-246 Lee SL, Durst F (1982) On the motion of particles in turbulent duct flows. Int J Multiphase Flow 8(2) 125-146... 

Lee SL, Wiesler MA (1987) Theory on transverse migration of particles in a turbulent two-phase suspension flow due to turbulent diffusion-1. Int J Multiphase Flow 13(1) 99-111... 

Kim and Char (2000) examine the rheology of a PES-DGEBA-DDM system during isothermal cure. They found a fluctuation in viscosity at phase separation that could be simulated by a two-phase suspension model that incorporated chemoviscosity effects. 

Grace JR. Contacting modes and behavior classification of gas-solid and other two-phase suspension. Can J Chem Eng 64 353-363, 1986. 

Consequently, two major factors affect the rheological properties of the mixture during phase separation (i) the change of composition in the epoxy-rich matrix and (ii) the variation of viscoelastic behavior of the phase-separated blend. The authors employed a two-phase suspension model as proposed by Graebling and Palierne [52] to explain the effect of viscoelastic behavior on the phase-separated mixture ... 

Lee SL (1987) Particle drag in a dilute turbulent two-phase suspension flow. Int J Multiph Flow 13(2) 247-256... 

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