Liquid-liquid extraction is an important unit operation in chemical engineering. The conventional designs such as mixer settler have lower-energy efficiency as the input energy is dissipated everywhere. Experimental studies have proved that the novel designs such as two-opposed-jet contacting device (TOJCD) microextractor allow energy to be dissipated close to the interface, and major part of energy is used for drop breakup and enhancement of surface renewal rates. It is very difficult to estimate the local variation of energy dissipation ( ) using experiments. Computational fluid dynamics (CFD) has been used to obtain at different rotating speed of the top disc and nozzle velocity. In this work, performance analysis of TOJCD microextractor has been carried out using Reynolds stress model. The overall value was found in the range of 50 to 400？W/kg and shear rate in the range of 100000？1/s. A semiempirical correlation for is proposed, and parity plot with experimental data has been plotted. 1. Introduction Liquid-liquid extraction (LLE) is an important unit operation in chemical engineering. Typical applications of the LLE are in metal extraction, aromatics nitration and sulfonation, polymer processing, waste water treatment as well as food and petroleum industries. LLE is a mass transfer operation in which a liquid solution (the feed) is contacted with an immiscible or nearly immiscible liquid (solvent) that exhibits preferential affinity or selectivity towards one or more of the components in the feed. Two streams result from this contact: the extract, which is the solvent-rich solution containing the desired extracted solute, and the raffinate, the residual feed solution containing little solute. The conventional designs such as mixer settler often have lower energy efficiency as the input energy is dissipated everywhere in the extractor. The transfer of solute from one phase to another is controlled by diffusion across the interface and often rate limiting. The process can be intensified and energy efficiency can be improved by novel designs such as two-opposed-jet contact device [1, 2], annular centrifugal extractors [3], impinging jet contactors [4], pulsed sieve plate extraction columns [5], and so forth. Experimental studies have proved that these novel designs offer higher energy efficiency. High energy dissipation and shear rates are used for breakup and enhancement of surface renewal rates. However, it is very difficult to estimate the local variation of energy dissipation using experiments. Computational fluid dynamics (CFD) can be used in
References
[1]
A. M. Dehkordi, “Application of a novel-opposed-jets contacting device in liquid-liquid extraction,” Chemical Engineering and Processing, vol. 41, no. 3, pp. 251–258, 2002.
[2]
A. M. Dehkordi, “Liquid-liquid extraction with chemical reaction in a novel impinging-jets reactor,” AIChE Journal, vol. 48, no. 10, pp. 2230–2239, 2002.
[3]
B. D. Kadam, J. B. Joshi, S. B. Koganti, and R. N. Patil, “Hydrodynamic and mass transfer characteristics of annular centrifugal extractors,” Chemical Engineering Research and Design, vol. 86, no. 3, pp. 233–244, 2008.
[4]
J. Saien, S. A. E. Zonouzian, and A. M. Dehkordi, “Investigation of a two impinging-jets contacting device for liquid-liquid extraction processes,” Chemical Engineering Science, vol. 61, no. 12, pp. 3942–3950, 2006.
[5]
R. L. Yadav and A. W. Patwardhan, “Design aspects of pulsed sieve plate columns,” Chemical Engineering Journal, vol. 138, no. 1–3, pp. 389–415, 2008.
[6]
C. S. Mathpatii, M. V. Tabib, S. S. Deshpande, and J. B. Joshi, “Dynamics of flow structures and transport phenomena, 2. Relationship with design objectives and design optimization,” Industrial and Engineering Chemistry Research, vol. 48, no. 17, pp. 8285–8311, 2009.
[7]
A. Tamir, Impinging Streams Reactors: Fundamentals and Applications, Elsevier, Amsterdam, The Netherlands, 1994.
[8]
B. N. Murthy and J. B. Joshi, “Assessment of standard k–ε, RSM and LES turbulence models in a baffled stirred vessel agitated by various impeller designs,” Chemical Engineering Science, vol. 63, no. 22, pp. 5468–5495, 2008.
[9]
C. S. Mathpati, S. S. Deshpande, and J. B. Joshi, “Computational and experimental fluid dynamics of jet loop reactor,” AIChE Journal, vol. 55, no. 10, pp. 2526–2544, 2009.
[10]
S. S. Deshmukh, S. Vedantam, J. B. Joshi, and S. B. Koganti, “Computational flow modeling and visualization in the annular region of annular centrifugal extractor,” Industrial and Engineering Chemistry Research, vol. 46, no. 25, pp. 8343–8354, 2007.
[11]
S. J. Wang and A. S. Mujumdar, “Mixing characteristics of 3D confined turbulent opposing jets,” in International Workshop and Symposium on Industrial Drying, pp. 309–316, Mumbai, India, December 2004.
[12]
S. J. Wang, S. Devahastin, and A. S. Mujumdar, “Effect of temperature difference on flow and mixing characteristics of laminar confined opposing jets,” Applied Thermal Engineering, vol. 26, no. 5-6, pp. 519–529, 2006.
[13]
S. J. Wang and A. S. Mujumdar, “Flow and mixing characteristics of multiple and multi-set opposing jets,” Chemical Engineering and Processing, vol. 46, no. 8, pp. 703–712, 2007.
[14]
A. Abdel-Fattah, “Numerical and experimental study of turbulent impinging twin-jet flow,” Experimental Thermal and Fluid Science, vol. 31, no. 8, pp. 1061–1072, 2007.
[15]
E. Gavi, D. L. Marchisio, and A. A. Barresi, “CFD modelling and scale-up of Confined Impinging Jet Reactors,” Chemical Engineering Science, vol. 62, no. 8, pp. 2228–2241, 2007.
[16]
A. W. Kleingeld, L. Lorenzen, and F. G. Botes, “The development and modelling of high-intensity impinging stream jet reactors for effective mass transfer in heterogeneous systems,” Chemical Engineering Science, vol. 54, no. 21, pp. 4991–4995, 1999.
[17]
D. L. Marchisio, “Large Eddy Simulation of mixing and reaction in a Confined Impinging Jets Reactor,” Computers and Chemical Engineering, vol. 33, no. 2, pp. 408–420, 2009.
[18]
C. Niamnuy and S. Devahastin, “Effects of geometry and operating conditions on the mixing behavior of an in-line impinging stream mixer,” Chemical Engineering Science, vol. 60, no. 6, pp. 1701–1708, 2005.
[19]
W. Li, Z. Sun, H. Liu, F. Wang, and Z. Yu, “Experimental and numerical study on stagnation point offset of turbulent opposed jets,” Chemical Engineering Journal, vol. 138, no. 1-3, pp. 283–294, 2008.
[20]
D. R. Unger and F. J. Muzzio, “Laser-induced fluorescence technique for the quantification of mixing in impinging jets,” AIChE Journal, vol. 45, no. 12, pp. 2477–2486, 1999.
[21]
Z. G. Sun, W. F. Li, and H. F. Liu, “Study on the radial jet velocity distribution of two closely spaced opposed jets,” International Journal of Heat and Fluid Flow, vol. 30, no. 6, pp. 1106–1113, 2009.
[22]
W. C. Reynolds, “Fundamentals of Turbulence for Turbulence Modeling and Simulation,” Report No. 755, Lecture Notes for Von Karman Institute, Agard., 1987.
[23]
B. E. Launder, “Second-moment closure and its use in modelling turbulent industrial flows,” International Journal for Numerical Methods in Fluids, vol. 9, no. 8, pp. 963–985, 1989.
[24]
K. Hanjali？, “Advanced turbulence closure models: a view of current status and future prospects,” International Journal of Heat and Fluid Flow, vol. 15, no. 3, pp. 178–203, 1994.
[25]
J. T. Davies, “Drop sizes of emulsions related to turbulent energy dissipation rates,” Chemical Engineering Science, vol. 40, no. 5, pp. 839–842, 1985.
