2) Hieber, W. and Woerner, A.: Z. Electrochem., 40, 252 6) Suda, S. : Doctoral thesis, Chem. Eng., Tokyo Metropolitan (1934) University, Tokyo (1967) 3) Hirata, M. and Suda, S.: Kagaku Kogaku, 31, 759 (1967) 7) Timmermans, J.: "Physico-Chemical Constants of Pure 4) Rivenq, F.: Bull. Soc. Chim. France, (8-9), 1606 (1963) 5) Stull, D.R.: Ind. Eng. Chern., 39, 517 (1947) 8) OrganicWilson, Compounds",A.L.: hid.Vol.Eng.2, ElsevierChem., 28,Publishing867 (1935) Co. (1965)
SALT EFFECT IN VAPOR-LIQUID EQUILIBRIUM ACETIC ESTER-ALCOHOL WITH POTASSIUM ACETATE AND ZINC CHLORIDE*
MOTOYOSHI HASHITANI AND MlTSUHO HIRATA Tokyo Metropolitan Univ., Tokyo
Vapor-liquid equilibrium data have been obtained for the systems methyl acetate-methanol and ethyl acetate-ethanol with potassium acetate and with zinc chloride at atmospheric pressure. The relative volatility increased little for the ethyl acetate-ethanol-potassium acetate system, but it increased con- siderably for other systems. The breaking of azeotropy was observed in the systems with zinc chloride. An empirical equation is proposed to correlate vapor-liquid equilibrium data for the systems contain- ing salt. The equation includes terms of both salt concentration and liquid composition.
Introduction nichrome wire wound round. The details of this ap- paratus and experimental procedure were reported pre- The salt effect in vapor-liquid equilibrium is a very viously2), but the procedure for the systems containing interesting subject and this problem has been studied zinc chloride was different in the analysis of liquid by many investigators. These data were collected by composition of the liquid phase. Whenthe liquid com- Ciparisl :). ponent mixture wasseparated from the liquid phase If a salt is added in liquid mixture, the relative sample containing zinc chloride by complete vaporization, volatility generally increases. The azeotropic point as reported previously2), it was observed that the organic disappears or is shifted to high composition, when the compounds decomposed and turned brown or black. mixture has an azeotropic point. However, the decomposition was not observed in the When the salt effect is utilized in distillation to equilibrium still. This means the decomposition may separate an azeotropic mixture, it is most desirable not occur in low concentration of zinc chloride, but that the azeotropy disappears by addition of salt. The may occur in high concentration. salt effect of calcium chloride on acetic ester-alcohol Acetic ester-alcohol mixture was introduced into the systems was reported previously3). The relative volati- still and the concentration was analyzed before adding lity of acetic ester increased but the azeotropy did not zinc chloride. The concentration was assumed to be disappear in these systems. the liquid phase concentration under equilibrium. For To study the salt effect of other salts, potassium each concentration of liquid component, a series of data acetate and zinc chloride were chosen as additives for for zinc chloride concentrations of 10, 20 and 30wt % the systems methyl acetate-methanol and ethyl acetate- was obtained. The samples for vapor and liquid phases ethanol, because of considerable solubility for organic were analyzed by gas chromatography in which a column compounds. Vapor-liquid equilibrium data at atmos- packed with Porapak-Q (Water Assoc. Inc.) was used. pheric pressure are reported in this paper for the above The concentration of potassium acetate in liquid phase systems. was analyzed by gravimetric analysis, in which the An empirical equation by which vapor-liquid equili- sample was dried at 150°C in a drying oven until a brium data for the systems containing salt can be cor- constant weight was obtained after liquid components related is proposed for these systems and others reported were evaporated carefully, while the concentration of previously2 ' 35. zinc chloride was analyzed by Mohr's method. The salt concentration was raised to saturation for potassium Experimental acetate, but to about 30wt%for zinc chloride to pre- vent decomposition of the organic compounds. The apparatus employed was a Smith-Bonner type6) still which had about ll volume and was heated by Experimental Results * Received on August 1, 1968 The experimental data' for vapor-liquid equilibrium
VOL.2 NO.2 1969 149 are given in Tables 1 and 2 for the systems methyl lity of methyl acetate increases at low methyl acetate acetate-methanol and ethyl acetate-ethanol with potas- composition for the methyl acetate-methanol system, sium acetate, and in Tables 3 and 4 with zinc chloride, while the relative volatility of ethyl acetate changes respectively. These data are also shown in Figs. 1> 2, little over the whole region for the ethyl acetate-ethanol 5 and 6 in which they are compared with data for system, although potassium acetate is fairly soluble in binary systems containing no salt in the literature5>7). that mixture at low ethyl acetate composition. The Potassium acetate was slightly soluble in ethyl acetate- salt effect of potassium acetate on the ethyl acetate- ethanol mixture at high ethyl acetate concentration so ethanol system is different from the ordinary salt effect that data for salt concentration for the system could in which salt effect is remarkable if the salt is soluble not be obtained exactly by the analytical method em- in the mixture. In both systems, the azeotropy does ployed. Therefore, there are a few blanks in C and not disappear by addition of potassium acetate. N columns of Table 2. The solubilities of potassium By addition of zinc chloride, the relative volatility acetate in boiling methyl acetate-methanol and ethyl of methyl acetate or ethyl acetate increases for the acetate-ethanol solutions are shown in Figs. 3 and 4. methyl acetate-methanol or ethyl acetate-ethanol system, By addition of potassium acetate, the relative volati- and the breaking of azeotropy was observed for these
Table I Vapor-liquid equilibrium data for methyl acetate- Table 2 Vapor-liquid equilibrium data for ethyl acetate- methanol-potassium acetate system (atmospheric pressure) ethanol-potassium acetate system (atmospheric pressure) x y t JV x y t C N
Saturation 0 0 0 0 49.2 0.240 80.5 Saturat20.1 ion 0.106 0.0353 0.216 47.4 0.235 0.0344 0.0883 78.1 18.4 0.0984 0.0696 0.333 45.3 0.228 0.0812 0.193 77.2 15.4 0.0843 0.116 0.446 40.9 0.206 0.120 0.248 76.3 13.8 0.0751 0.203 0.543 33.6 0.173 0.196 0.326 74.9 10.2 0.0592 0.292 0.622 26.2 0.138 0.246 0.379 73.9 8.93 0.0533 0.412 0.668 17.4 0.0959 0.300 0.412 73.2 6.78 0.0416 0.527 0.693 10.4 0.0602 0.350 0.434 73.0 6.39 0.0406 0.603 0.706 7.59 0.0458 0.409 0.492 72.6 4.31 0. 0282 0.711 0.728 2.55 0.0162 0.432 0.480 72.3 3.28 0.0217 0.764 0.761 1.59 0.0104 0.520 0.542 72.1 1.88 0.0131 0.820 0.797 .1 0.711 0. 00483 0.546 0.558 72.1 1.62 0.0115 0.859 0.827 .4 0.426 0. 00296 0. 667 0. 647 72.2 0.644 0. 00487 0.950 0.907 .4 0.094 0. 00070 0.739 0.694 72.6 0.226 0. 00178 1.000 1.000 .7 0.037 0. 00028 0.819 0.769 73.0 0.113 0. 00093 About llw wt: 0.902 0.836 74.1 - 0.0861 0. 250 ll.0 0.0430 0.942 0.904 75.2 - 0.0973 0.276 ll.0 0.0436 1.000 1.000 76.6 - 0.162 0.385 ll.2 0.0476 0.289 0.520 10.9 0.0523 Table 4 Vapor-liquid equilibrium data for ethyl acetate- 0.396 0.589 10.8 0.0565 ethanol-zinc chloride system (atmospheric pressure) 0.485 0.662 10.8 0. 0608 x y t C N Table 3 Vapor-liquid equilibrium data for methyl acetate- 0 0 180 85 0.52 methanol-zinc chloride system (atmospheric pressure) 0.0468 0.102 78.0 10.8 0.0403 c 0.112 80.4 21.6 0.0854 N x y t 0.123 86.2 32.5 0.137 0 0 192 91 0.707 0. 167 0.279 74.8 7.15 0. 0288 0.0879 0.217 60.8 10.4 0. 0294 0.310 77.0 18.5 0.0788 0.245 62.2 21.5 0.0667 0.381 84.3 32.7 0.150 0.271 65.3 32.2 0.111 0.295 0.413 74.2 ll.1 0.0498 0.174 0.352 58.3 ll.0 0.0344 0.485 77.3 22.0 0. 103 0.386 59.5 21.2 0.0711 0.560 83.9 33.0 0.163 0.431 62.8 32.2 0.121 0.423 0.527 73.6 10.3 0. 0499 0.302 0.483 56.3 ll.4 0.0403 0.607 76.9 21.2 0.107 0.531 58.0 22.6 0. 0873 0.721 83.0 31.9 0.168 0.606 62.3 34.1 0.145 0.534 0.619 73.7 10.3 0.456 0.600 55.2 10.8 0. 0436 0.0533 0.730 77.5 21.0 0.682 57.5 22.5 0.0983 0.113 0.840 82.9 32.2 0.778 62.3 34.0 0.162 0.179 10.6 0.617 0.720 55.2 10.4 0.0473 0.663 0.724 74.8 0. 0588 21.7 0.810 57.9 20.8 0.101 0.857 78.8 0.124 32.9 0.904 61.6 31.9 0.166 0.912 83.2 0.194 0.763 0.836 56.2 10.6 0. 0529 0.809 0.860 76.5 10.5 0. 0629 0.927 59.1 0.120 0.938 79.6 21.8 0.134 0.958 61.9 0.192 0.961 82.6 32.9 0.206 0.891 0.952 57.7 ll.6 0. 0625 0.917 0.960 77.7 10.6 0.0670 0.979 58.2 21.7 0.124 0.981 79.4 21.2 0.136 0.987 61.4 34.2 0.210 0.987 81.8 32.9 0.214 1.000 1.000 133 79 0.674 1.000 1.000 143 76 0.547
150 JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Fig. I Vapor-liquid equilibrium data for methyl acetate- Fig. 2 Vapor-liquid equilibrium data for ethyl acetate-ethanol methanol with potassium acetate at atmospheric pressure saturated with potassium acetate at atmospheric pressure
Fig. 3 Solubility of potassium acetate in boiling methyl Fig. 4 Solubility of potassium acetate in boiling ethyl acetate-methano! solution acetate-ethanol solution
Fig. 5 Vapor-liquid equilibrium data for methyl acetate- Fig. 6 Vapor-liquid equilibrium data for ethyl acetate-ethanol methanol with zinc chloride at atmospheric pressure with zinc chloride at atmospheric pressure
VOL.2 1969 NO.2 151 systems. In particular, the increase of relative volati- Eq. (2) is approximately the same as Eq. (3) lity is larger at high ester composition than at low ester composition. From the standpoint of distillation, this log^ = kN (3) means that zinc chloride must be an effective salt as an additive. proposed by Johnson and Furter4), because Nis general- ly small and in this case N/(l-N) is nearly equal to Potassium acetate is soluble in methanol and ethanol, N. but little soluble in methyl acetate and ethyl acetate Eq. (l) is tested for the systems reported in this as shown in Figs. 3 and 4. Zinc chloride is very soluble paper and the systems reported previously2>3). in these organic compoundsand solubilities of zinc The values of A and B are decided from the inter- chloride are 91, 85, 79 and 76wt %in methanol, ethanol, sect and the slope of the graphical plot of log(a*/a)/ methyl acetate and ethyl acetate, respectively. These {N/(l-N)} vs. x on semi-log, paper. The values of A data were obtained from rough measurement in which zinc chloride was dissolved in boiling liquid in Erlen- and B and average deviation in y whenexperimental data are correlated by using these A and B, are given meyer flasks and these salt solutions were analyzed for in Table 5. For the ethanol-water-calcium chloride the concentration of zinc chloride. system, the data cannot be correlated by the same values of A and B for saturation and below saturation. Discussion However, the data can be correlated precisely when the values of A and B are decided for saturation and The salt effect in vapor-liquid equilibrium is probably below saturation, respectively. For the ethyl acetate- due to the difference of salt interaction with liquid ethanol-potassium acetate system, the salt effect is so components. The interaction must be due not only to the salt concentration but also to the composition of small that the data cannot be correlated by Eq. (l). the liquid component. Based on these considerations, Except for the above two systems, the experimental data can be correlated by Eq. (l). From testing Eq. the following empirical equation, by which vapor-liquid (l) with experimental data, it is suggested to be ap- equilibrium data for a system containing salt can be propriate that Eq. (l) includes not only the term of correlated, is proposed. salt concentration but also the term of liquid composi- tion.
Here a and as are relative volatilities of binary system Conclusion and of system containing salt, respectively. A and B are salt effect parameters for the system, x is mole It has been reported that the salt effect is consider- fraction of more volatile component in liquid phase able, if the salt is soluble in the liquid mixture. How- (salt free basis). N is salt concentration in mole frac- ever, potassium acetate does not behave in this way tion. If B is 1 in Eq. (l), Eq. (l) becomes for the ethyl acetate-ethanol system, i. e. it is soluble in this mixture at low concentrations of ethyl acetate, but its salt effect is insignificant. The salt effect of zinc chloride is so large that the azeotropies of methyl acetate-methanol and ethyl acetate- Table 5 Salt effect parameters in Eq. (I) anddeviation ethanol systems are broken. Zinc chloride may also in y when experimental data are correlated by Eq. (l) greatly affect vapor-liquid equilibria of other systems, B av. deviation Systems (mole fract. ) because it is very soluble not only in water but in organic compounds, besides which it has the ability of ethanol-water-calciu m 3.4 0.706 0.0043 chloride (saturation) dehydration. // n 6.0 0.550 0.0020 The vapor-liquid equilibrium data for the systems (below saturation) z -propanol-water- calciu m 5.2 1.0 0.0078 containing salt are correlated by Eq. (l), which includes chlor ide terms of both salt concentration and liquid composition. w-propanol-water- calciu m 3.3 1.0 0.0166 chlor ide methyl acetate-methanol- 3.4 1.38 0.0156 Nomenclature calcium chloride ethyl acetate-ethanol- 0.86 5.67 0.0154 A, B = salt effect parameter in Eq. (l) calcium chloride C = concentration of salt in liquid phase n-butyl acetate-n-butanol- 0.90 5.07 0.0152 k =salt effect parameter in Eq. (3) calcium chloride = mole fraction of salt in liquid phase (ternary system) methyl acetate-methanol- 1.0 7.2 0.0072 [-] potassiumacetate = boiling temperature of liquid [°C] ethyl acetate-ethanol- = mole fraction of more volatile component in liquid potassium acetate phase (salt free basis) [-] methyl acetate-methanol- 0.53 19. 95 0.0091 zinc chloride = mole fraction of more volatile component in vapor ethyl acetate-ethanol-zinc 0.78 12.97 0.0102 phase [-] chlor ide = relative volatility of binary system [-] = relative volatility of the system containing salt [-]
152 JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Literature Cited 4) Johnson, A.I, and Furter, W.F.: Can. J. Chem. Eng., 2, 78 (1960) 1) Ciparis, J. N. : "Data of Salt Effect in Vapor-Liquid Equili- 5) Perry, J. H.: "Chemical Engineer's Handbook", 4th. Ed. brium ", Lithuanian Agricultural Academy, Kaunas, U. S. S. R., McGraw-Hill, New York, 1963 1966 6) Smith, T.E. andBonner, R.F.: Ind. Eng. Chem., 41, 2867 2) HashitanL M., Hirata, M. and Hirose, Y. : Kagaku Kogaku, (1949) : 32, (No.2) 182 (1968) 7) Teshima, T., Hiyoshi, S., Matsuda, H., Monma, S. and 3) Hashitani, M. and Hirata, M.: J. Chem. Eng. Japan, 1, Iwabe, S.: J. Chem. Soc. Japan, Ind. Chem. Sect., 55, 801 (No. 2) 116 (1968) (1952)
HEAT TRANSFER IN LAMINAR FLOW IN VERTICAL CONCENTRIC ANNULI
NOBUO MITSUISHI, OSAMU MIYATAKE** AND MITSUGU TANAKA Dept. of Chem. Eng., Kyushu University, Fukuoka
A theoretical analysis of heat transfer to Newtonian fluids in laminar flow in concentric annuli was developed under the conditions of constant temperature inner wall and insulated outer wall, taking into account the temperature dependency of viscosity and density. The arithmetic mean Nusselt number was obtained as a function of the Graetz number with K, flwl'fJLo and Grw/Rew as parameters. Furthermore, experimental data were obtained for two different diameter ratios K. It was found that theoretical predictions are in reasonably good accord with experimental data.
Introduction (1) The temperature of the inner wall isuniform and the outer wall is insulated. The analytical solutions of problems involving heat (2) The laminar velocity profile is fully developed transfer to Newtonian fluids flowing in concentric an- at the inlet to the heat transfer section. nuli with constant temperature inner wall and insulated (3 ) Thermal conduction in the longitudinal direc- outer wall under fully developed laminar flow conditions tion is negligible. have been given in the form of an infinite series con- (4) Heat produced by viscous dissipation is neg- taining eigen values and eigen functions by R. Viskanta4) lected. and A. P. Hatton & A. Quarmby3). These theoretical (5) The fluid temperature is uniform at the inlet approaches have been developed under the assumptions to the heat transfer section. that the physical properties of the fluids are inde- (6) A steady state has been attained. pendent of temperature and natural convection effects Then the equation of motion of a flow in a vertical are negligible. annulus can be expressed as However for many industrial heat transfer problems 1 d ( du\ , dp , ,^ the change in physical properties due to heating or r dr\ drJ dz cooling must be considered. In the case of downwardflow, it suffices to substitute Hence the authors have extended the analysis to the -g for g. The following linear relations will be used case of heat transfer with temperature dependent viscos- to express the temperature dependency of the fluid ity and density. Experimental data obtained for two different diameter ratios k (=2n/2r0) were in reason- able agreement with the theoretical predictions.
Theoretical Analysis The coordinates and geometry are shown in Fig. 1, and in the course of the analysis the following assump- tions are made: Received on October 30, 1968 Presented at the 33rd Annual Meeting of the Society of Chemical Engineers, Japan, at Kyoto, April 1968 Research Institute of Industrial Science, Kyushu Univer- sity Fig. I Diagram of the coordinate system
VOL.2 1969 NO.2 153