J.
H E N R Y R U S H T O N
DESIGN TRENDS I N MIXING AND MIXERS The need f o r mass transfer rate data as afected
mixing
stimulates fundamental studies as well as mixer design ncreased attention has been given There is a need for more accurate data so that mixers can be properly designed for the many new continuous processing operations. The design and fabrication of mixers with particular attention to meeting the requirements of operation in empty vessels, during change of liquid level and other emergency conditions, was discussed by Dykeman (6). In addition to such situations not described before, there are two other articles dealing with fabrication techniques with respect to corrosion (26), to various types of mixers used in Europe (22). Several significant works dealing with measurement of various aspects of mixing have appeared. Lamb, Manning, and Wilhelm (73) describe anelectrical conductivity probe for measuring very rapid fluctuations of concentration in very small elements of volume. Cengel, Knudsen, and others (3) offer an apparatus for the measurement of emulsion characteristics by means of light transmittance. Hougen and Walsh described a pulse-testing method for following blending operations ( 7 0 ) . Liquid-liquid extraction by the use of rotating mixing devices received a tremendous amount of attention during ihe past few years. At least 18 works of importance have been published during the past year on mass transfer and other
Ito scale-up techniques.
+Circle
No. 9 on Readers' Service Card
facets of liquid-liquid mixing. Treybal (34) covered this whole subject in I&EC recently. Continuous countercurrent extraction columns are now in wide use and holdup data for the rotating disk column is now available (72). A significant articIe dealing with the stability of emulsions and agitation requirements necessary to produce them has been published by Church and Shinnar (4). Mixer-settler arrangements received wide attention (5, 77, 75, 3 7 ) . In all cases scale-up data are available to show how the different units can be used to contact iwo liquids both in a small scale model and in larger size. Mixer-settler arrangements are among the oldest type of mass transfer equipment but few data have been published on their performance and scale-up requirements. New information on mass transfer in mixing vessels of common design used in industry was presented by Olney (23). Reports on the measurement of interfacial area in liquidliquid mixing and the effect of interfacial tension and other physical properties on interfacial area and interfacial resistances appeared (17,78, 30). An article by Blasinski (7) discusses the effectiveness of turbine-type mixers, and by a technique not used before for the purpose, has confirmed the effectiveness of using turbine mixers with baffles. Hills (9) attempts to relate the
scale-up of liquid-liquid systems, although few quantitaiive data are available to justify the conclusions. Coalescence and dispersion of drops formed in liquid-liquid mixing has received considerable attention. I t has only recently been recognized that coalescence and redispersion of drops in a mixing vessel are of themselves significant factors in the rate mechanism of mass transfer. Data (36) and of of Vanderveen Matsuzawa and Miyauchi (16) are significant and open new fields for a better understanding of the mass transfer phenomena. Groothuis and Zuiderweg (8) d'ISCUSS the effect of mass transfer on coalescence. Undoubiedly much more work will be done in this field in the near future. Mixing and agitation of Newtonian and non-Newtonian fluids are receiving considerable attention. This area needs clarification and the articles by Metzner, Feehs, and others (79), Calderbank and MooYoung (Z), and Richards (29) are significant. Metzner has done a large amount of work in this field and has reported on power requirements. Calderbank has published some very significant information on various aspects of mixing. His latest paper extends our present information on power characteristics to a much larger range of variables. Practical applications in mixing of viscous materials involve equipmenl (Continued on Page 60) VOL. 5 4
NO. 8
AUGUST
1962
59
I 1
I
This filter thinks for itself After pre-setting the controls on this filter, you can for-
get it! Automatically, the controls “read” the gauges that measure pressure, flow and cake thickness. Then, when the pressure becomes excessive, the flow is insufficient or the cake has reached its maximum thickness; the filter
I
I
stops; cleans and pre-coats itself and starts the filtering cycle all over again. Control is positive. Human judgment errors are eliminated. Filtration quality is precisioncontrolled; yet, quality control is flexible and efficient. Send data today for an analysis of your filtration problem. Details of other
NIAGARA
II I
I
for silicone rubber manufacturin? (74) and a new mixer arrangement for the dispersion of pigments in viscous liquids (32). Solids mixing has been practiced for many years but few data on performance have been available until rrcently. Many interesting articles appeared in 1961 dealing with solid-solid mixing. Shinnar and Naor (33) developed a statistical method for testing randomness, which appears to be of considerable use. Yagi, Daizo, and others (38) studied the axial mixing of solid particles in moving beds. NeJv and unique data on the mixing of solid particles in cylindrical vessels equipped with paddle-type impellers appeared (26, 25). Mori, limbo, and others (20) studied the mixing of wetted powders. This is a problem not often encountered but probably will become of increasing importance. Blending of metal powders and pigments, how to pretest before setting up blending schedules, and the effects of ayglomeration on mixing appeared (7). Heat transfer problems invol\ ingmixing are of interest. Vincent, Hougen, and Dreifke (37) studied the effect of mixing on the heat transfer coefficients in the shell and tube heat exchangers. Studies on the oxidation of sulfite solutions bv air distribution ha\ e been reported (27); different impeller shapes Ltere compared. Mixing in a gas-solid fluidized bed mas discussed by van Deemter (35). The rate of solution of benzoic acid in caustic solution has been measured (28). Murakami (27) reports on experiments made in a continuous flow system for mixing tanks in series ; unsteady state conditionr were analbzed.
filters are in Bulletin NC-457
and in the Chemical Engineering Catalog. J . Henry Rushton is Professor Chemical Engineering at Purdue L‘niuersitjl, and Technical Ahisor t o ,2lixing EquQjment Co., Rochester, 1V. Y . H e has authored I e E C ’ s M i x i n g review since 7946. AUTHOR of
N I A G A R A FILTERS AMETEK
A D I V I S I O N OF A M E T E K , ING.
E A S T MOLINE, ILLINOIS
Circle No. 11 on ReaUers’ Service Card
60
INDUSTRIAL A N D ENGINEERING CHEMISTRY
LITERATURE CITED ( 1 ) Blasinski, H., Przemysl Chem. 39, 768 (1960). ( 2 ) Calderbank, P. H., Moo-Young, M. B., Trans. Znst. Chem. Engrs. (London) 39, 22 (1961). ( 3 ) Cengel, J. A,, Knudsen, J. G., Landsberg, A , , Farqui, A. A., Can. J . Chem. Eng. 39, 189 (1961). (4) Church, J. M., Shinnar, R . , IND.ENG. CHEX.53, 479 (1961). (5) Davis, A. T., Colven, T. .J., A.Z.CI2.E. Journal 7, 73 (1961). ( 6 ) Dykeman, M., Chem. Eng. Progr. 57, No. 4, 122 (1961); Zbid, No. 5, 123. ( 7 ) Fischer, J. J., IND. ENG.CHEM.53, 34A (January 1961). (8) Groothuis, H. G., Zuiderweg, F. J., Chem. Eng. Sei. 12, 288 (1960). ( 9 ) Hills, B. A,, Brit. Chem. Eng. 6 , 104 (1961). (10) Hougen, J. O., Walsh, R . A., Chem. Eng. Progr. 57, 69 (1961). (11) Johnston, T. R., Robinson, C. W., Epstein, N., Can. J. Chcm. Eng. 39, 1 (1961). (12) Kung, E. Y . , Beckmann, R. B., A.1.Ch.E. Journal 7, 319 (1961). (13) Lamb, D. E., Madning, F. S., Wilhelm, R. H., Zbid., 6 , 683 (1960). (14) Liermann, A. O., Miller, D. E., IND. EKG.CHEM.53, 702 (1961). (15) Long, R. B., Fenske, M. R . , Ibid., 53, 791 (1961). (16) Matsuzawa, H., Miyauchi, T., Kagaku Kogaku 25, 582 (1961). (17) McManamey, W. J., Chem. Eng. Sei. 15, 210 (1961). (18) McManamey, W. J., Zbid., 15, 251 (1961). (19) Metzner, A. B., Feehs, R. H., others, A.Z.Ch.E. Journal 6 , 3 (1961). (20) Mori, Y., Jimbo, G., others, Kagaku Kogaku 25, 813 (1961). (21) Murakami, Y., Zbid., 25, 653 (1961). (22) Neidhardt, S., Chem.-Zngr.-Tech. 33, 824 (1961). (23) Olney,R.B.,A.Z.Ch.E. J.7,348(1961). (24) Otake, T., Kitaoka H., Tone, S., Kagaku Kogaku 25, 186 (1961). (25) Otake, T., Kitaoka, H., Zbid., 25, 178 (1961). (26) Parker, N. H., Chem. Eng. 67, 112 (1960). (27) Pavlushenko, I . S., Braginskiy, L. N., Brylov, V. N., Zhur. Prikiad. Khim. 34, 805 (1961). (28) Pavlushenko, I. S., Smirnov, N. N., Romankov, P. G., Zbid., 34, 312 (1961). (29) Richards, J. W., Brit. Chem. Eng. 6 , 454 (1960). (30) Rodriguez, F., Grotz, L. C., Engle, D. L., A.Z.Ch.E. Journal 7, 663 (1961). (31) Ryon, A. D., Daley, F. L., Lowrie, R. S., U.S. At. Energy Comm. ORNL2961, 1960. (32) Schaefer, P., Chem.-Zngr.-Tech. 33, 421, 493 (1961). (33) Shinnar, R., Naor, P., Chem. Eng. Sci. 15, 220 (1961). (34) Treybal, R. E., IND. ENG. CHEM. 54, 5, 55 (1962). (35) van Deemter, J. J., Chem. Eng. Scz. 13, 143 (1961). (36) Vanderveen, J. H., U.S. At. Energy Comm. UCRL-8 733. (37) Vincent, G., Hougen, J., Dreifke, G. E., Chem. Eng. Progr. 57, 48 (1961). (38) Yagi, S., Daizo, K., others, Kagaku Kogaku 25, 476 (1961).
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TOLHURST CENTRIFUGALS AMETEK
A D I V I S I O N OF AMETEK, INC.
EAST MOLINE, I L L I N O I S
Circle No. 12 on Readers’ Service Card
VOL. 5 4
NO. 8
AUGUST 1962
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