Taylor vortices

This is most easily achieved by rotating the inner cylinder and keeping the outer fixed in the laboratory frame. Note, however, that this geometry leads to the formation of Taylor vortex motion if inertial effects become important (Reynolds number Re 1). Most rheo-NMR experiments are actually performed at low Re. In the cylindrical Couette, the natural coordinates are cylindrical polar (q, <(>, z) so the shear stress is denoted and is radially dependent as q 2. The strain rate across the gap is given by [2]... 

Preparation of Monodisperse, Spherical Oxide Particles by Hydrolysis of Metal Alkoxide Using a Couette-Taylor Vortex Flow Reactor... 

Figure 12 Experimental set-up of Taylor vortex photocatalytic reactor (Dutta and Ray, 2004) (1) motor, (2) speed controller, (3) gear coupling, (4) UV lamp, (5) sample collection point, (6) lamp holder, (7) outer cylinder, (8) catalyst-coated inner cylinder.

Figure 14 Progress of time-dependent Taylor vortex flow around critical Reynolds number, 6 = 111. (Dutta and Ray, 2004).

Figure 15 Photograph of flow pattern at different Reynolds number, (a) Taylor vortex flow (Re = 177), (b) wavy vortex flow (Re = 505), (c) weakly turbulent vortex flow (Re = 3027), and (d) turbulent vortex flow (Re = 8072) (Dutta and Ray, 2004).

As an alternative to a cascade of CSTR trains, a novel continuous reactor with a Couette-Taylor vortex flow (CTVF) has been proposed, which can realize any flow pattern between plug and perfectly mixed flows [361-366]. A continuous Couette-Taylor vortex flow reactor (CCTVFR) consists of two concentric cylinders with the inner cylinder rotating and with the outer cylinder at rest. Figure 29 shows a typical flow pattern caused by the rotation of the inner cylinder. 

Nomura et al. [360,364] first utilized a Couette-Taylor vortex flow reactor (CTVFR) for the continuous emulsion polymerization of St to clarify its char-... 

The major droplet disruption occurs in the immediate vicinity of the rotating blades where shear forces are highest, e.g., due to the presence of Taylor vortexes. The effectiveness of droplet disruption depends on the geometry of the mixer and the rotational speed of the blades. Operational parameters include blade and vessel geometries and rotation speed of blades. 

Ohashi K, Tashiro K, Kushiya F, Matsumoto T, Yoshida S, Endo M, Horio T, Ozawa K, and Sakai K, Rotation-induced Taylor Vortex enhances filtrate flux in plasma separation, ASAIO Trans. 1988 34(3) 300-307. 

Forney et al. [85] were among the first authors to study the potential advantages of the liquid-liquid extraction using a Taylor-vortex column. In the column, the power input is evenly distributed throughout the entire volume of the contactor, and the rotor and tank stirrers are roughly equal in diameter [74]. The maximum shear is one to two orders of magnitude lower than in a continuously stirred contactor. This leads to a between 10-fold and 100-fold increase in the area inside the continuously stirred tank that is exposed to constant maximum shear. 

Figure 8.3 The Taylor-vortex column. All symbols have the same meaning as in Eq. (6). The membrane globules ( ) are dispersed in the feed phase of the system via the rotation of the inner cylinder of the Taylor-vortex column, and the flow pattern, depicted by the dashed lines on the right-hand side of this figure, is established.

Park [74] studied the efficiency of the ELM with non-Newtonian hquids in the removal of Zn, Pb, Ni and Cd from a simulated industrial wastewater using the Taylor-vortex column. The author adapted the shrinking core mathematical model of Liu and Liu [86] for quantitative description of the mass-transfer kinetics of the process [74]. The LM was prepared by the dissolution of 5 g dm of polyisobutylene in Soltrol 220 (see above). After complete dissolution of the polymer, the membrane phase... 

The ELMs could be apphed if the concentrations of precious metals in the wastewater range from 0.1 to 10,000 mg dm [90]. The apphcation of the ELMs based on non-Newtonian hquids and the Taylor-vortex column carry a lot of promise for industrial apphcations in the near future. Several commercial applications have been reported for ELM pertraction. Passivating is an operation commonly used in the galvanization industry to improve the resistance of metal parts to corrosion [87]. Metal parts are submerged into the passivating bath and become coated with Cr and/or Co to provide a protective layer against corrosion [87]. 

Removal of phenol from wastewaters has been studied using non-Newtonian ELMs and the Taylor-vortex column. It was found that a decrease in the surfactant concentration in the ELM leads to a lower surfactant accumulation per unit interfacial area at the feed phase/ELM interface. As a result, the higher was the efficiency of phenol removal from the wastewater [97, 98]. An increase in the volume of the stripping phase in the ELM could result in a reduction of the LM thickness [74]. 

The most promising is the application of the Taylor-vortex column with Taylor-Couette flow. Sorption of hydrophobic organic compounds can lead to under estimation of actual removal efficiency of wastewater treatment, as weU as cross-contamination of the batches of the effluent due to release ofthe sorbed solute molecules. This is supported by the results ofthe laboratory studies, along with the ease ofthe potential scale-up. The critical part in the context ofthe removal of organic compounds from wastewater(s) is the material of the inner cylinder. The surface of the inner cylinder provides a potential sorption surface for hydrophobic organic molecules. Since the PTFE price could be prohibitive for the scale-up, stainless steel, or other materials should be explored as replacements for potential industrial applications. 

Forney, L. J., SkeUand, A. H. P., Morris, J. F., HoU, R. A. (2002). Taylor-vortex column Large shear for liquid-liquid extraction. Separation Science and Technology 37 2967-2986. 

Taylor Vortex Reactor (TVR) Suspended Karpel et al., 1997 Sczechowski et al., 1995a. 

FIGURE 2.2. Taylor vortex reactor in operation (Reprinted from Chem. Eng. Sci.., 50(20), J.G. Sczechowski, C.A. Koval and R.D. Noble, A taylor vortex reactor for heterogeneous photocatalysis, pp. 3163-3173, Copyright 1995, with permission from Elsevier)... 

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