MASS TRANSFER PERFORMANCE IN PULSED DISC AND DOUGHNUT EXTRACTION COLUMNS

Transcription

1 Brazilian Journal of Chemical Engineering ISSN Printe in Brazil Vol. 28, No. 03, pp , July - September, 2011 MASS TRANSFER PERFORMANCE IN PULSED DISC AND DOUGHNUT EXTRACTION COLUMNS M. Torab-Mostaei 1*, A. Ghaemi 2, M. Asaollahzaeh 1 an P. Pejmanza 1 1 Nuclear Science an Technology Research Institute, Nuclear Fuel Cycle Research School, Phone: (+9821) , Fax: (+9821) , En of North Karegar Av., P.O. Box: , Tehran, Iran. mmostaei@aeoi.org.ir 2 Department of Chemical Engineering, Iran University of Science an Technology, P.O. Box: , Tehran, Iran. (Submitte: March 8, 2011 ; Revise: April 16, 2011 ; Accepte; April 19, 2011) Abstract - Mass transfer performance is presente for a 76 mm iameter pulse isc an oughnut extraction column for the toluene-acetone-water system. The experiments were carrie out for both mass transfer irections. The mass transfer ata are interprete in terms of the axial iffusion moel, thus accounting for continuous phase axial ispersion. The effect of operating parameters on the overall volumetric mass transfer coefficients has been investigate. The results show that the column performance increases with an increase in pulsation intensity. At high pulsation intensity, however, the overall volumetric mass transfer coefficient ecreases ue to the prouction of very fine isperse roplets. It was also foun that the column performance ecreases with both an increase in isperse phase velocity an a ecrease in continuous phase velocity. An empirical correlation for preiction of the continuous phase overall mass transfer coefficient is erive in terms of the overall Sherwoo number, Reynols number an isperse phase holup for each mass transfer irection. The preiction of continuous phase overall mass transfer coefficients from the presente correlations is in goo agreement with experimental ata. Keywors: Mass transfer coefficient; Pulse isc an oughnut column; Axial iffusion moel; Holup. INTRODUCTION Liqui-liqui extraction has long been a key operation in many separation processes foun in the chemical, pharmaceutical, environmental, oil, foo, nuclear, an hyrometallurgical inustries for prouct purification an/or raw material recovery. Inustrially, more than 25 kins of liqui-liqui contactors have alreay been ientifie (Blass et al., 1986). Insofar as liquors from hyrometallurgical inustries are concerne, on account of the slow extraction rates exhibite by most metal systems of practical interest, mixer-settlers have been frequently aopte. However, in recent years, the evelopment of new extractants with superior selectivity an efficiency characteristics has le to an increasing interest in the use of agitate columns for the treatment of hyrometallurgical liquors (Moreira et al., 2005). Recently, the pulse isc an oughnut column has been installe in a number of metallurgical applications aroun the worl; for example, at the Western Mining Corporation Olympic Dam operation in South Australia, ten columns have been operating for the extraction of uranium. It has also been use in the nuclear inustry an in the chemical inustry. This column has also been extensively applie to reprocess spent nuclear fuel in France an Japan (Angelov an Journe, 1990; Angelov et al., 1998). In comparison to mixer-settlers, the column has been state to have several avantages, viz., its lower cost, simplicity of esign, less space consumption, an reuction of organic loss (Movsowitz et al., 1997; Jahya et al., 1999). *To whom corresponence shoul be aresse

2 448 M. Torab-Mostaei, A. Ghaemi, M. Asaollahzaeh an P. Pejmanza Having etermine the column iameter, the mass transfer performance shoul next be consiere in calculation of the column height. In early esign proceures, ieal plug-flow conitions were assume in both phases for the estimation of the height require for the esire separation. It is well-known that axial ispersion in one or two phases leas to consierable eviations from ieal plug-flow, resulting in an increase in the height require to achieve the esign specification. Two istinct types of moels are in use, namely the iffusion moel, which assumes turbulent axial iffusion of solute superimpose on plug flow of the phase uner consieration, an the backflow moel, which assumes well-mixe non-ieal stages between which backflow occurs. Two moels represent iealize limiting cases, but in practice the iffusion moel is approache by ifferential extractors an the backflow moels are evelope for step-wise contactors, although the results for these two moels are almost ientical when the stage number of the backflow moel is large enough. On this basis, the state of the art for the esign an analysis of an extraction column is to use the iffusion or backflow moel, where one parameter accounts for all eviations from the ieal plug flow behavior (Bart et al., 2008). Many investigations have concentrate on the evelopment of numerical solutions to escribe the operational characteristics of the column (Aoun Nabli et al., 1998; Aoun Nabli an Guirau, 1997; Barin-Monnier an Guirau, 2003); however, no firm esign an scale-up criteria have yet been propose an few ata are available on the mass transfer performance of this type of column. For the purpose of establishing a proper esign proceure for pulse isc an oughnut extraction columns, there is thus a nee for reliable correlations for preiction of the overall mass transfer coefficients. This paper presents a stuy of the mass transfer performance of a pulse isc an oughnut column. The effects of pulsation intensity, continuous an isperse phase velocities, an mass transfer irection on the overall volumetric mass transfer coefficients are investigate. An empirical correlation for preiction of the overall mass transfer coefficients is erive in terms of the overall Sherwoo number, Reynols number an isperse phase holup. EXPERIMENTAL Figure 1 shows the schematic arrangement of the experimental apparatus. The main column section consiste a 74 cm long glass tube of 76 mm internal iameter, enclosing a stack of 30 pairs of iscs an oughnuts, mae of 2 mm stainless steel sheet. The iscs an oughnuts were arrange alternately an space 10 mm apart, resulting in a 20 mm compartment height; they were hel in place by means of three 3.2 mm o.. SS tie ros with SS spacer sleeves. The iscs were 67 mm in iameter an the oughnut apertures were 36 mm, giving an open free area of 23.5%. A settler 112 mm in iameter at each en of the column permitte the liquis to coalesce an ecant separately. The column was pulse by blowing air at the require amplitue an frequency into the pulse leg. The air pressure was controlle by a regulator to provie pulses of the require amplitue in the column while the frequency of the pulses was controlle by using two solenoi valves. The inlet an outlet of the column were connecte to four tanks, each of 80 l capacity. The flow rates of both phases were controlle via rotameters. The liqui-liqui interface was maintaine approximately 250 mm above the top compartment. This was achieve by using an optical sensor. A solenoi valve (a normally close type) was provie at the outlet stream of heavy phase. This valve receive electronic signals from the sensor. When the interface location was going to change, the optical sensor sent a signal to the solenoi valve an the aqueous phase was allowe to leave the column by opening the iaphragm of the solenoi valve. The organic phase was allowe to leave the column via overflow. A toluene-acetone-water system was use in this stuy. This system is recommene as a stanar test system by the European Feeration of Chemical Engineering (E.F.C.E.). Distille water was use as the continuous phase an technical grae solvents of at least 99.9 wt% purity were use as the isperse phase. The physical properties of the liqui-liqui systems use in the experiments are given in Table 1. It shoul be note that, uner mass transfer conitions, a egree of uncertainty surrouns the estimation of physical properties (particularly interfacial tension), since these vary not only with the solute concentrations, but also along the column. In this stuy, the values of physical properties have been assume to correspon to the mean of acetone concentration in the continuous an isperse phases. The mean value of the acetone concentration was obtaine at the inlet an outlet of the column. Liqui-liqui equilibrium ata of the liqui system were taken from Míšek et al. (1985). When starting a run, the solvent an water phases were first mutually saturate, after which acetone was ae to the isperse or continuous phase to give a concentration of about 3.5 wt% acetone. Samples of each phase were taken at their inlets to the column an use for etermination of the initial solute concentration. Brazilian Journal of Chemical Engineering

3 Mass Transfer Performance in Pulse Disc an Doughnut Extraction Columns Continuous Phase Tanks 2. Disperse Phase Tanks 3. Rotameters 4. Optical level Controller 5. Pulsation Leg 6. Solenoi Valves 7. Pumps 8. Regulator Figure 1: Schematic iagram of the pulse isc an oughnut column Table 1: Physical properties of the chemicals use at 20 C (Míšek et al., 1985). Physical property Toluene-acetone-water ρ 3 c (kg / m ) ρ 3 (kg / m ) μ c (mpa.s) μ (mpa.s) σ (mn / m) Dc D (m /s) (m /s) The amplitue an frequency of pulsation were next ajuste to the esire values an, after filling the column with the continuous phase, the isperse phase was introuce. The interface position was then maintaine at the esire height, an the system was allowe to reach the steay state, which usually necessitate 4 5 changes of the column volume. At the en of each experiment, samples of the organic an aqueous phases were taken at their respective outlets. The solute concentrations were then etermine by gas chromatography. After reaching the steay state at the esire flow rate, the rops were photographe using a Nikon D5000 igital camera. Drop imensions were then etermine using AutoCAD software. For elliptical rops, both the vertical an horizontal axes were measure. Drop sizes were converte to absolute imensions by comparing the measure values with the isc or oughnut thickness. Approximately 150 rops per photo were analyze. Finally, the rops were classifie into 0.1 mm size intervals, which were use to calculate the Sauter mean rop iameter, 32, as follows: n i= 1 32 = n i= 1 3 i i n 2 i i n (1) Holup measurements were obtaine by using the shut own (isplacement) metho. In orer to use this metho, at the en of a run, the inlet an outlet valves were shut simultaneously an the isperse phase was allowe to isengage to the interface at Brazilian Journal of Chemical Engineering Vol. 28, No. 03, pp , July - September, 2011

4 450 M. Torab-Mostaei, A. Ghaemi, M. Asaollahzaeh an P. Pejmanza the top of the column. A perio of min was allowe for the isperse phase to settle. The change in interface height between operation an after settling was measure an then converte into the corresponing volume to etermine holup. Visual observation showe that mixer-settler, transition, an emulsion regimes exist in the column epening upon the flow rates an the pulse characteristics. However, experiments at pulsation intensities below 2.4 cm/s were not performe as the main concern of the work was to etermine the column performance uner inustrial operating conitions. MODELING Base upon the axial iffusion moel an mass balance in the column over the ifferential elements of the column with total effective height H, the set of equations for the steay state process was establishe as follows, for constant superficial velocities V x an Vy at any given pulsation intensity: 1 x * x + N ox (x x ) = 0 Z Px Z 1 y Vx * y+ N ox (x x ) = 0 Z P Z V where y y (2) (3) Px = HV x /Ex, Py = HV y /Ey, Z= h/h, N k ah ox ox =. Vx In the present stuy, the isperse phase axial ispersion was assume to be negligible, i.e., 1/P =0, with the continuous phase axial mixing coefficient estimate by the following correlation given by Jahya et al. (2009): E c k1 k k 2 3 k4 μc A Vc V Vμc Δρ hc Af Vc σ = k (4) with k= , k 1 =0.246, k 2 =-0.157, k 3 = an k 4 =1.062 for the toluene-acetone-water system. The three bounary conitions are as follows: At the top of the column (Z=0): x = Pe x(x x) Z At the bottom of the column (Z=1): (5) x 0 Z = (6) y = y (7) By using the continuous phase axial ispersion coefficient, the measure isperse an continuous phase concentrations, together with the equilibrium ata, an the bounary conitions, the experimental values of continuous phase overall volumetric mass transfer coefficients (k oc a) are calculate from Equations (2) an (3). RESULTS AND DISCUSSION The overall performance of an extraction column can be expresse in terms of the overall mass transfer coefficient, k oc, an the interfacial area, a. The effect of pulsation intensity on the overall volumetric mass transfer coefficient is shown in Figure 2. As expecte, a higher pulsation intensity results in a lower value of the average rop iameter an a higher value of the isperse phase holup. The interfacial area increases with both effects. However, the reuction of rop size results in a reuction of internal circulation an turbulence in the rops an, consequently, the overall mass transfer coefficient ecreases with an increase in pulsation intensity. At low an meium values of the pulsation intensity, the effect of the interfacial area is larger than that of the overall mass transfer coefficient an, consequently, the overall column performance increases with an increase in pulsation intensity. At high values of the pulsation intensity, however, the overall mass transfer starts to fall significantly with the formation of rigi roplets. The column performance is also largely affecte by the axial mixing at high values of the pulsation intensity. For this range of operating conitions, the volumetric overall mass transfer coefficient ecreases with an increase in agitation rate. This suggeste that an optimum point exists where the performance of the column increases initially with pulsation intensity an thereafter ecreases as the circulating roplets become smaller an more rigi. Brazilian Journal of Chemical Engineering

5 Mass Transfer Performance in Pulse Disc an Doughnut Extraction Columns 451 Figure 2 also shows that the column performance varies with the irection of mass transfer. When the mass transfer occurs from the continuous to the isperse phase, the concentration of the solute in the raining film between two approaching rops will be lower than in the surrouning continuous liqui. For mass transfer in the opposite irection, the concentration will be corresponingly higher. The resulting graients of interfacial tension will retar rainage an inhibit coalescence in the former case an accelerate rainage an coalescence in the latter case. Therefore, the c transfer tens to prouce smaller rops than that in the opposite irection. Smaller rop size results in an increase in both the isperse phase holup an the interfacial area for mass transfer in the irection of the continuous to isperse phase (c ). However, the mass transfer performance in the case of c is higher than in the opposite irection c, in spite of a lower interfacial area (lower holup, larger rop size). This higher performance is a result of increase mass transfer rates in the roplets of bigger sizes ue to the presence of oscillations create between the roplets, which is enhance by the Marangoni effects (Gouron an Casamatta, 1991; Torab-Mostaei an Safari, 2009). The effect of isperse phase velocity on the overall volumetric mass transfer coefficient is shown in Figure 3. The experiments show that the isperse phase holup increases with an increase in isperse phase velocity. It was also observe that increasing the flow rate of the isperse phase tens to increase the average rop size, since a higher organic phase flow rate leas not only to a larger rop formation but also to higher coalescence frequencies. The interfacial area increases with an increase in holup an ecreases with mean rop iameter. In these experiments, it was observe that the effect of holup on interfacial area is larger than that of rop size, i.e., interfacial area increases with an increase in isperse phase velocity. However, the overall mass transfer coefficient ecreases with an increase in isperse phase velocity. In this case, it was foun that the overall mass transfer coefficient is the ominant factor in etermining the mass transfer performance an, consequently, the column performance ecreases with increasing isperse phase velocity. The effect of continuous phase velocity on k oc a is illustrate in Figure 4. The isperse phase holup increases with an increase in continuous phase velocity ue to the increment of the rag force between isperse rops an the continuous phase. The Sauter-mean rop iameter i not change significantly with progressive increases in the continuous phase flow rate. So, the interfacial area increases with an increase in holup when the rop size is approximately constant. It was also observe that the overall mass transfer coefficient increases with an increase in continuous phase velocity. The mass transfer performance increases with an increase in both the overall mass transfer coefficient an the interfacial area. The operating variables an experimental results are liste in the Appenix. Figure 2: Variation in the mass transfer performance with pulsation intensity Figure 3: Variation in the mass transfer performance with isperse phase velocity Brazilian Journal of Chemical Engineering Vol. 28, No. 03, pp , July - September, 2011

6 452 M. Torab-Mostaei, A. Ghaemi, M. Asaollahzaeh an P. Pejmanza Figure 4: Variation in the mass transfer performance with continuous phase velocity Preiction of the Continuous Phase Overall Mass Transfer Coefficient One of the main objectives of this stuy is to propose an equation for preiction of the overall mass transfer coefficients in pulse isc an oughnut columns. The continuous phase overall mass transfer coefficient (k oc ) can be obtaine by iviing the volumetric coefficient by the interfacial area (a=6x / 32 ). For the escription of mass transfer coefficients, Kumar an Hartlan (1999) evelope semi-empirical preictive correlations for the mass transfer coefficients of the continuous an isperse phase in pulse, Karr, Kühni an rotating isc columns, as represente by: where: 1/2 1/3 1/3 c,rigi c c Sh = Re Sc ReSc (10) 2 Sh = 50 + Pe π ( ) 1/2 c, c ( 1 ε ) ( Af ) 2 2 π ψ= 2ε C h c (11) (12) where C 1 =C 2 =4.33 for pulse columns. The overall mass transfer coefficient can be obtaine via the twofilm moel as follows: Sh / (1 x ) Sh c c,rigi Sh Sh / (1 x ) c, c = 1 1 m = + (13) k k k oc c / Re Re /3 1/3 Sc 1/3 Vsμc 1 c c C ψ ρ g g σ +κ σ ( ) ( ) 3 1/ / ReSc ρ 2 1/3 0.7 ρc Sh = ReSc ψ ρc 1+ C 2/3 2 1 g g σ +κ 1/3 (8) (9) Since no publishe correlations are available for preiction of mass transfer coefficient in pulse isc an oughnut columns, the Kumar an Hartlan correlations are commonly use for escription of the mass transfer performance in pulse isc an oughnut columns (Van Delen et al., 2006; Grinbaum, 2006). In the present work, the possibility of using these correlations for preiction of the overall mass transfer coefficient is examine. The comparison of experimental results with those calculate by the Kumar an Hartlan correlations is shown in Figure 5. Van Delen et al. (2006) also use these correlations for escription of mass transfer performance of extraction of caprolactam with toluene in a pulse isc an oughnut column. Brazilian Journal of Chemical Engineering

7 Mass Transfer Performance in Pulse Disc an Doughnut Extraction Columns 453 They observe that these correlations satisfactorily escribe the separation performance of the process in a pulse isc an oughnut column. Contrary to their observation, Figure 5 shows that the Kumar an Hartlan correlations o not have enough accuracy for preiction of the overall mass transfer coefficients in the column. column. The correlation constants are calculate by using the least squares metho with "Eviews software" version 3.1. Figure 6 shows the resulting comparison of experimental ata with preicte results, using Equations (14) an (15). As can be seen in this figure, the suggeste correlations estimate the experimental ata with a relative eviation of 10.52%. Figure 5: Comparison between experimental ata an the preictions of the Kumar an Hartlan correlations For this reason, empirical correlations are erive for preiction of continuous phase overall mass transfer coefficients in terms of the overall Sherwoo number, Reynols number an isperse phase holup for ifferent irections of mass transfer as follows: oc ( ) 0.16 ( ) Sh = Re 1 x oc c < Re < ( ) 0.12 ( ) Sh = Re 1 x where Sh oc Re = c 9.45 < Re < c (14) (15) koc32 = (16) D Vρ 32 s c μc (17) in which 32 is the Sauter-mean rop iameter an V s is the slip velocity between the two phases through the Figure 6: Comparison between experimental ata an the preictions of Equations (14) an (15) CONCLUSIONS This stuy provies valuable information on the mass transfer performance of pulse isc an oughnut columns, for which there are currently only limite results. The experiments show that the overall volumetric mass transfer coefficient increases with an increase in pulsation intensity. However, the mass transfer performance ecreases at high values of the pulsation intensity ue to increase entrainment an poor extraction efficiency, with the prouction of rigi isperse roplets. The mass transfer performance is foun to be higher for solute transfer in the irection of isperse to continuous phase ( c) ue to the inuce effect of interfacial turbulence. The experimental finings inicate that the column mass transfer performance increases with an increase in continuous phase velocity an a ecrease in isperse phase velocity. An empirical correlation for preiction of the overall continuous phase Sherwoo number is propose base on the Reynols number an isperse phase holup for each mass transfer irection. These correlations can be use for the esign an scale-up of the column. Brazilian Journal of Chemical Engineering Vol. 28, No. 03, pp , July - September, 2011

8 454 M. Torab-Mostaei, A. Ghaemi, M. Asaollahzaeh an P. Pejmanza NOMENCLATURE a interfacial area m 2 m -3 A amplitue of pulsation m C orifice coefficient C 1, C 2 parameters of empirical correlations E c continuous phase axial mixing m 2 s -1 frequency f frequency of pulsation s -1 g acceleration ue to gravity m s -2 h c compartment height m H effective height of the column m k, k 1, k 2, constants, see Equation (4) k 3, k 4 k c continuous-phase mass m s -1 transfer coefficient k isperse-phase mass transfer m s -1 coefficient k oc overall continuous-phase mass s -1 transfer coefficient k o overall isperse-phase mass s -1 transfer coefficient N ox number of true transfer units P Péclet number = HV/E Pe c continuous-phase Péclet number = 32 V s /D c Re Reynols number= 32 V s ρ c /μ c Sc c continuous-phase Schmit number = μ c /(ρ c D c ) Sc isperse-phase Schmit number = μ /(ρ D ) Sh c continuous-phase Sherwoo number = k c 32 /D c Sh isperse-phase Sherwoo number = k c 32 /D c Sh oc overall continuous-phase Sherwoo number = k oc 32 /D c V superficial velocity m s -1 V s slip velocity m s -1 x isperse phase holup x mass fraction of acetone in the continuous phase x * equilibrium mass fraction of acetone in the continuous phase corresponing to the isperse phase y mass fraction of acetone in the isperse phase Greek Symbols σ interfacial tension N m -1 Δρ ensity ifference between kg m -3 phases μ viscosity Pa.s ρ ensity kg m -3 κ viscosity ratio ε fractional free area ψ power issipate per unit m 2 s -3 mass Subscripts c x y Superscripts continuous phase isperse phase x-phase (continuous phase in the present case) y-phase (isperse phase in the present case) * equilibrium value inlet to column REFERENCES Angelov, G. an Journe, E., Simulation of the flow patterns in a isc an oughnut column. Chem. Eng. J., 45, (1990). Angelov, G., Gouron, C. an Line, A., Simulation of flow hyroynamics in a pulse solvent extraction column uner turbulent regimes. Chem. Eng. J., 71, 1-9 (1998). Aoun Nabli, M. S., Guirau, P. an Gouron, C., CFD contribution to a esign proceure for isc an oughnut extraction columns. Chem. Eng. Res. Des., (Part A), 76, (1998). Aoun Nabli, M. S. an Guirau, P., Numerical experimentation: a tool to calculate the axial ispersion coefficient in iscs an oughnuts pulse solvent extraction column. Chem. Eng. Sci., 52, (1997). Barin-Monnier, N. an Guirau, P., Lagrangian simulations contribution to the knowlege of iscs an oughnuts pulse solvent extraction columns hyroynamics. Chem. Eng. Process, 42, (2003). Bart, H. -J., Drumm, C. an Attarahih, M. M., Process intensification with reactive extraction columns. Chem. Eng. Process, 47, (2008). Blass, E., Golman, G., Hirschemann, K., Mihailowitsch, P., an Pietzsch, W., Progress in liqui-liqui extraction. Ger. Chem. Eng., 9, (1986). Brazilian Journal of Chemical Engineering

9 Mass Transfer Performance in Pulse Disc an Doughnut Extraction Columns 455 Gouron, C. an Casamatta, G., Influence of mass transfer irection on the operation of a pulse sieve-plate pilot column. Chem. Eng. Sci., 46, (1991). Grinbaum, B., Review Article: The existing moels for simulation of pulse an reciprocating columns How well o they work in the real worl? Solvent Extr. Ion Exc., 24, (2006). Jahya, A., Stevens, G. W. an Pratt, H. R. C., Floo point an isperse phase holup in a pulse isc an oughnut liqui-liqui extraction column. In Proceeings Chemeca '99, Newcastle, Australia (1999). Jahya, A., Stevens, G. W. an Pratt, H. R. C., Pulse isc-an-oughnut column performance. Solvent Extr. Ion Exc., 27, (2009). Kumar, A. an Hartlan, S., Correlations for preiction of mass transfer coefficients in single rop systems an liqui-liqui extraction columns. Chem. Eng. Res. Des. (Part A), 77, (1999). Míšek, T., R. Berger an J. Schröter, Stanar test systems for liqui extraction stuies. EFCE Publ. Ser., 46, 1 (1985). Moreira, É, Pimenta, L. M., Carneiro, L. L., Faria, R. C. L. an Mansur, M. B., Ribeiro, C. P. Jr., Hyroynamic behavior of a rotating isc contactor uner low agitation conitions. Chem. Eng. Comm., 192, (2005). Movsowitz, R. L., Kleinberger, R. an Buchalter, E. M., Application of Bateman pulse columns for uranium solvent extraction. Bateman Projects Lt., Israel (1997). Torab-Mostaei, M. an Safari, J., Mass transfer coefficients in pulse packe extraction column. Chem. Eng. Process, 48, (2009). Van Delen, M. L., Vos, G. S., Kuipers, N. J. M., an e Haan, A. B., Extraction of caprolactam with toluene in a pulse isc an oughnut column, Part III: Mass transfer characteristics. Solvent Extr. Ion Exc., 24, (2006). APPENDIX The experimental values obtaine in the present work are liste in Tables A-1 an A-2. Table A -1: Experimental ata obtaine in the experiments (mass transfer in the irection of isperse to continuous phase) No. A (cm) f (1/s) Q c (l/h) Q (l/h) x 32 (mm) k oc (m/s) Brazilian Journal of Chemical Engineering Vol. 28, No. 03, pp , July - September, 2011

10 456 M. Torab-Mostaei, A. Ghaemi, M. Asaollahzaeh an P. Pejmanza Table A -2: Experimental ata obtaine in the experiments (mass transfer in the irection of continuous to isperse phase) No. A (cm) f (1/s) Q c (l/h) Q (l/h) x 32 (mm) k oc (m/s) Brazilian Journal of Chemical Engineering