교반조에서 비혼화성 액상(n-헥산/물)계의 액-액분산

김태옥; 김동욱; 전종한

Journal of the Korean Industrial and Engineering Chemistry, Vol.4, No.3, 537-543, September, 1993

Export Citation

교반조에서 비혼화성 액상(n-헥산/물)계의 액-액분산

Liquid-Liquid Dispersion of an Immiscible Liquid Phase (n-Hexane/water) System in a Stirred Tank

김태옥, 김동욱, 전종한

초록

N-헥산과 증류수로 이루어진 비혼화성 액상계에서 교반에 의한 액-액분산을 해석하였다. 교반기는 blade형태가 flat, 60mesh와 40mesh의 금망, 그리고 60mesh금망의 외부에 금속띠를 두른 4가지의 6-bladed turbine 교반기를 사용하였다. 실험결과, 동일한 교반속도에서 유기상의 분산정도와 교반기의 소요동력은 blade형태가 flat>solid edged>60mesh>40mesh의 순서이었으며 유기상의 부피비가 증가할수록 완전분산에 필요한 최소교반속도가 증가되었다. 또한 분산상의 액적의 평균직경은 교반속도의 증가에 따라 감소하였으며 동일한 교반속도에서는 solid edged32)은 다음과 같이 유기상의 부피비(φ)와 Weber number(N_we)의 함수로 나타낼 수 있었다.
d₃₂/D=a(1+bφ)N_we^-0.6

The effect of agitation on liquid-liquid dispersion was investigated in an immisible liquid phase(n-hexane/water) system. Four different types of six-bladed turbine impellers were used : a flat blade, two screen blades and a solid edged 60 mesh screen blade. We found that the extent of dispersion of organic phase and power consumption of agitator were decreased in the order of flat, solid edged, 60 mesh, and 40 mesh blades at same agitation speed. And the minimum agitation speed for complete dispersion of organic phase was increased with increasing volume fraction of organic phase. Also, mean diameter of liquid droplets of dispersed phase was decreased with increasing agitation speed and it was increased in the order of solid edged, flat, 60 mesh, and 40 mesh screen blades at same agitation speed. At complete dispersion, the minimum power consumption was not vary significantly with impeller blade types, but the solid edged screen blade impeller gave the smallest and uniform sizes of liquid droplets, and it had a good performance for liquid-liquid dispersion. In this condition, Power number was not affected by Reynolds number and it was constant in turblent flow region, and Sarter mean diameter(d₃₂) of liquid droplets was expressed as a function of volume fraction of organic phase(φ) and Weber number(N_we) as follows:

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[1] Macdonald RW, Priet EL, Chem. Eng. Prog., 47, 363 (1951)

[2] Skelland AHP, Lee JM, AIChE J., 27, 99 (1981)

[3] Nagata S, "Mixing - Principles and Applications," John Wiley & Sons, New York (1975)

[4] Brown DE, Pitt K, Chem. Eng. Sci., 29, 345 (1974)

[5] Narsiham G, Gupta JP, Chem. Eng. Sci., 34, 257 (1979)

[6] Mlynek Y, Reshnick W, AIChE J., 18, 122 (1972)

[7] Rounsley RR, AIChE J., 29, 597 (1983)

[8] Kim TO, Chun JH, J. Korean Ind. Eng. Chem., 2(3), 209 (1991)

[9] McCabe WL, Smith JM, Harriott P, "Unit Operations of Chemical Engineering," 4th ed., McGraw-Hill, New York (1985)

[10] Dean JA, "Lange's Handbook of Chemistry," 12th ed., McGraw-Hill, New York (1979)

[11] Tatterson GB, "Fluid Mixing and Gas Dispersion in Agitated Tanks," McGraw-Hill, New York (1991)

[12] Chatzi EG, Gavrielides AB, Kiparissides C, Ind. Eng. Chem. Res., 28, 1704 (1989)