Application 0f Draft Tube in the Reduction of Backmixing Rate in Oscillatory Flow in a Baffled Column

Mohd Sobri Takriff(1*), Zuhrina Masyitah(2)

(1) Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
(2) Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
(*) Corresponding Author


Oscillatory flow in a baffled tube/column is an efficient way to enhance mixing in a straight smooth column. However, liquid oscillation moving back and forth across the baffle causes backmixing which is a disadvantage when plug flow is desired. This paper presents results from a study conducted to reduce the backmixing rate in oscillatory flow in a baffled column with the use of a draft tube. Results of this study showed that backmixing increases with oscillation velocity and decreases with liquid flow rate. The use of a draft tube reduces backmixing. The backmixing reduction is proportional to the ratio of L/Do However, the draft tube can not be extended too long because it disrupts the flow behavior in the column and creates dead zones near the baffle region. The draft tube length is maximized by extending it to both sides of the baffle, provided that the L/De on each side of the baffle is at 0.67 or less.

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  1. Brunold, c.R., Hunn, J.C.B., Mackley, M.R. and Thomson, J.w. "Experimental Observations on Flow Patterns and Energy Losses for Oscillatory Flow in Ducts Containing Sharp Edges". Chern. Eng. Sci., 44, 1989, 1227-1244.
  2. Hewgill,M.R.,Mackley,M.R.,Pandit,A.B.&Pannu, S.S., Enhancement of Gas-Liquid Mass TransferUsing OscillatoryFlow in Baffled Tubes.Chern.Eng. Sci., 48(4), 1993, 799-803.
  3. Howes,T and Mackley, M.R.ExperimentalAxial Dispersionfor OscillatoryFlowThrough a BaffledTube. Chern. Eng. Sci. 45, 1349-1358 (1990).
  4. Ingham,J., Slater,M.J. and Retamales,J. "Single Phase AxialMixingStudiesin PulsedSieve Plate Liquid-LiquidExtraction Columns". Trans.I ChernE.72(A),1995,492-496.
  5. Mackley,M.R. Using OscillatoryFlow to Improve Performance. The Chern. Eng. February, 1987.
  6. Mackley,M.R."ProcessInnovationUsingOscillatory Flow Within BaffledTubes". Trans.IChemE. 69, 1991, 197-199.
  7. Magelli.F,Fajner.D, and Pasquali,G. "Multistage Mixer Column III". Chern. Eng. Sci. 37, 1986, 141-145.
  8. Ni, X. and Gough, P. "On The Discussion of Dimensionless Groups Governing OscillatoryFlowin a BaffledTube".Chern. Eng. Sci. 52, 1997,3209-3212.
  9. Roberts, E.P.L. "The Simulation of Chaotic Advection for Application to Process Engineering". Trans.IChemE. 69, 1991, 208-210.
  10. Takriff, M.S, Penney, W.R. and Fasano, J.B. "Interstage Backmixing of an Aerated Multistage Mechanically-Agitated, CompartmentedColumn".The Canadian Journal of Chern.Eng.76,1998,365-369.
  11. Xu, B.C., "Interstage Backmixing inCompartmented Agitated Columns: Experimental Determination and Correlation". Ph.D. Dissertation, University of Arkansas, 1994.
  12. Vidaurri, F.C. & Sherk, F.T. "Low Backmixing in Multistage Agitated Contactors Used as Reactors. AIChE Journal. 31(5),1985, 705- 710.
  13. ZuhrinaMasyitah."Backmixingin OscillatoryFlow in a BaffledColumn"MScThesis,Universiti KebangsaanMalaysia,2001.


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