INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1951
(303)Weir, H. M., U. S. Patent 2,485,249(Oct. 18, 1949). (304) Wendel, K.,Planta, 37, 604-11 (1950). (305) White, L.,and Schneider, C. H., J . Am. Chem. SOC.,71,2945-6 (1949). (306)Wiig, E. O.,and Juhola, A. J., Ibid., 71,561-8 (1949). (307) Wilga, J., Mindler, A. G., and Gilwood, M. E., “Decolorieing Solutions by a Granular Synthetic Resin,” 117th Meeting AM. CHEM.SOC., Houston, Tex., 1950. (308) Williams, T.I., Anal. Chim. Acta, 2,635-48 (1948)(in English). (309) Wolock, I., and Harris, B. L., IND. ENG.C H ~ M 42, . , 1347-9 (1950). (310) Wustefeld, H., Arch. Metallcunde, 3, 223-4 (1949).
9m
55
(311) Yang, J. T., and Haissinsky, M., Bull. SOC. chim. France, 1949, 540-7. (312) Zafir, M., Folia Pharm. (Turkey), 1, No. 3, 29-31 (1949) (in German). (313) Zettlemoyer, A. C., Chand, A., and Gamble, E., J. Am. Chem. Soc., 72, 2752-7 (1950). (314) zettlemoyer, A. c.9Healey, F. H., and Fetsko, J. M., “Adsorption of Gases on Cadmium Oxide,” 117th Meeting Ana. CHEM.SOC., Houston, Tex., 1950. (315)zhdanovg s* Dokl&J Ahad* S*S-S*R*v681 99-102 (1949). RECEIVED November 13, 1950.
CENTRIFUGATION ~ - - _ _ _ _
JAMES 0.MALONEY
UNIVERSITY OF K A N S A S , LAWRENCE, K A N .
A
flow relationships in a basket centrifuge has been presented by Burak and Storrow (17). They pointed out t h e limitations of the equation suggested by Maloney (479, and developed others suitable for experimental verification. I n their experimental study they suspended maize starch particles of about 12 microns in diameter in water and centrifuged them in a perforated basket fitted with a fabric medium. A comparison of data on cakes of various thicknesses showed t h a t the starch was uniformly packed. The rate of passage of water through various thicknesses of previously deposited cake was not proportional to the square of the speed of rotation, as predicted by the theoretical equations. The authors attempted, without success, to correlate the data by putting the deviations into the permeability term. Then they made filtration studies on deposited filter cakes and also on cakes first formed in the centrifuge and then carefully inserted into the filter cell. Their results were somewhat confusing and bear out the results of Wilcox (81),who was forced t o conclude that his filter-cell experiments did not give results comparable with those obtained in a centrifuge. I n such a study, some simplification might have been obtained by the employment of carefully sized and incompressible materials, such as silica. German workers (14) reported descriptions and performance data on several centrifuges that were used for separating gaseous isotopes. Studies were conducted on xenon, krypton, selenium, and uranium isotopes. The rotors were of the tubular variety subdivided into from 1 to 10 chambers. The rotor diameters were as great as 12 cm. and the lengths were as great as 67 cm. Speeds u p to 60,000 revolutions per minute were employed. In the separation of UFc isotopes, the separation factors ranged from 1.01 to 1.06. An extensive study of the variables affecting the clarification of sulfate liquors in a Bird continuous centrifuge has been reported (68). The main value of this investigation to readers outside the paper industry lies in the proof that the performance of this machine is qualitatively predictable from theoretical considerations. Conclusions of general interest include: The percentage of solids in the liquor in the centrifuge increased rapidly above a certain feed rate; a decrease in the operating temperature of the feed liquor from 195’ to 165” F. roughly doubled the percentage of solids in the effluent; a marked increase in the percentage of solids in the effluent occurred if the feed liquor contained more than 10% of solids. Richardson and Lyons (60)have obtained operating information on the dewatering of coal in a Bird continuous unit (Figure 1). Because of the
marked improvement in the material available on centrifugation i s noted. Several investigations obtained sufficient data to permit a comparison of theory-with practice (77, 58). A new textbook (76) on unit operations providesan improved treatrnent,of centrifugation. Continuous centrifuges for handling solids and liquids have been combined with mixers to extract castor oil, linseed oil, and soya oil from the ground seeds continuously (6). The First unclassified information on the separation of uranium isotopes using centrifuges has appeared (74).
D
N
URING the past year several books appeared containing sections on centrifugation. The most voluminous treatment occurs in Perry’s third edition of the “Chemical Engineers’ Handbook” (SO). -Only minor changes have been made in this material since the first edition of 1934. The section might have been improved by providing a bibliography on the subjeot, by including descriptions and performance data on the units for continuously handling slurries, and by bringing the cost information up to date. All of the information necessary is readily available (27, 47-61, 68, 81). The discussion by Brown et al. (16) represents a marked improvement over those in earlier texts. These authors give, for the first time, an illustrated description of modern equipment, a discussion of the theoretical aspects of the subject, a bibliography, and some problems. But this discussion, like those in all the other standard texts, might be improved by the inclusion of illustrative examples and a comparison of calculated results with actual performance data. Such examples and comparisons are furnished in relation to other operations b u t not for centrifugation. Golding (35) has published an adequate treatment of centrifuges for laboratory use. His discussion includes a number of illustrative examples exhibiting the method for calculating; the time required for certain particles to be separated by centrifugal action; the relative centrifugal force in test tube units; and the pressures developed in the centrifuging tubes. The account could serve.as an introduction to the field. Nichols and Bailey (64)have written extensively on the ultracentrifuge as a laboratory device. Review articles on the subject have continued t o appear. They include a description of lubricating oil centrifuges together with operating instructions ( I O ) ; a review of applications of the ultracentrifuge in research and practice (45); and a review (in German) of American centrifugal practice and its developments (63). F U N D A M E N T A L STUDIES
Noteworthy progress is being made in the development of fundamental information in this field. Investigators are beginning t o study the variables affecting the performance of centrifugal machines. One of the few theoretical treatments of the
INDUSTRIAL AND ENGINEERING CHEMISTRY
56
Vol. 43, No. P
est to anyone confronted with a similar problem. N E W EQUIPMENT
The new equipment which has come to the reviewer's attention during the last year is listed in Table I, together with the source and the field of application. APPLICATIONS
Figure I. Bird Centrifugals for Dewatering Fine Coal after Washing These epnbilugals handle feeds
UP
to 500 gallons per minute
K e x applications of centrifugal equipment are listed in Table 11. Some of them, however, deserve special mention. A three-stage solvent extraction process suitable for recovering castor oil, linseed oil, or soya oil has been developed, which uses continuous Bird centrifuges to separate the solids from the solvent after they have been combined in the mixers (6). The margarine, lard, and other edible oil industries are turning to centrifugal methods as a solution to their separation problems (20, 6 7 , 79). T h e pharmaceutical houses are using c e n t r i f u g e s m o r e and more in production operations (66).
and coal up to 60 tons per hour N E W TECHNIQUES AND AUXlLlARlES
specific nature of the operation and of certain operational difficultiw, only limited conclusions could be drawn. Quartz sands containing 8 to 10% moisture were successfully dewatered in a sugar refinery centrifuge (82). As would be expected, the residual moisture decreased with the decreasing thickness of the sand layer. It ranged from 2.2 to 2.8%. Adler and Blanchard (1j made an analysis of the errors inherent in the Lamm scale method for the measurement of concentration gradients in the ultracentrifuge. They found that under the condition usually applied, the Lamm formula gives a systematic error of about 1%. The theory of the separation of suspended particles in a supercentrifuge has been elaborated (71). T h e effect of gradients of centrifugal force on the potential of siniple galvanic cells has been studied ( 4 6 ) ; in the experiment, the method of making the electrical connections between the rotating apparatus and the measuring equipment will be of inter-
A technique for using centrifugal force for the filtration of materials out of blood and plasma has been described (40). In certain cases it is necessary t o maintain materials being centrifuged just above 32" F. A simple procedure for doing this hae been described (7%). I n determining the sedimentation constants of materials by means of the ultracentrifuge, one must know the temperature of the solution. A device has been described which permits the determination of' the solution's temperature to within 0.1"C. (26). The application of centrifugal techniques to the separation of small quantities of material has been reported by Feldman el al. (29). A new and versatile microcentrifugation apparatus has been described ($6). Auxiliaries of interest to centrifuge users include: a plastic cover ior a 40-inch centrifuge which permits the operator to observe the filling operation and prevents spillage and spashing ( 7 ) ; an acrylic rotor for the Fisher-Stern ultracentrifuge (11);
Table 1.
Name S-15 continuous centrifuge HS-24 universal centrifuge Wort clarifier Beer clarifier Dorr Clone Special basket Portable refrigerated Centrifuge
R-8 laboratory unit Batch centrifugal clarifier PY-14 cylindrical Super-D-Cantor DV-2 controlled solids discharge
N e w Equipment Developments in Centrifugals Application Manufacturer or Designer Baker Perkins, Inc. For relatively free-draining materials For filtering finely divided solids Baker Perkins, Iuc. De Lava1 Separator Co. Brewing industry De Lava1 Separator Co. Brewing industry Dorr C o . .4 separator employing a high velocity stream directed in a circular path to separate solids from liquids Fletcher Works, Inc. For throwing down mercury in thermometers International Equipment Go. For biological, pharmaceutical,. and other applications where temperature control IS important Memo Centrifugal Co. Small unit for research and development work Sackett Study of desliming operations prior to selection of Bird continuous machine Sharples Corp. Continuous Separation of liquids from solids with good liquid clarity Sharples Corp. Clarification of flnids containing solids (pineapple juice)
Reference (46) (46) (62)
(62)
(8%
INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1951
11.
(21) Demmerle, R. L., et al.,IND. ENG. CREM., 42, 2-12 (1950). Denhard, H. W., U. S. Patent 2,490,421(Dee. 6, 1949). Dixon, A. G., private comm u n i c a t i o n (October 1950). Druel, M., and Huit-Fidor. G., French Patent 933,500 (April 22. 1948). Dubbs, C. A., Anal. Chem., 21, 1273-6 (1949). Ecker, P. G., etal., Rev. Sci. Instruments, 20, 799-801 (1949). Eckhardt, H., Chem. Eng., 54,NO. 5 , 121-3 (1947). Evans, H. C., and Winsor, P. A., Proc. Inst. Sewage P u r t & u t h (Enol.) 1949, 365-70. Feldman, I., et al., Anal. C h m . , 22, 837-8 (1950). Flowers, A. F.,and Hull, S. H.. in “Chemical Eneineers’ Handbook,” 3rd ed., pp. 992-1013,New York, McGraGHill Book Co., 1950. Foa, Mario, Ital. Patent 443,602 (Dee. 29, 1948). Gerard, F., Bull. assoc. anciens 6tud. brass. univ. Louvain, 45, 149-58 (1949). Golding, H.B.,in “Technique of Organic Chemistry,” Vol. 111, pp. 143-70, New York, Interscience Publishers, 1950. Hessey, R. W. G., and Manning, R. N., Proc. Qzaemland SOC. Sugar Cane Technol., 16,87-107 (1949). Hoover, M. M., Chem. Eng., 57,No.4,132-4 (1950). Industria mecannica moline ed affini, Ital. Patent 443,510 (Dec. 27, 1948). Jones, E. P., U. S. Patent 2,475,141(July 5,1949). Kastens, M.L.,and Kaplan, J. F., IND. ENO.CHEM.,42,402-13 (1950). Kenyon, R. L., and Boehmer, N., Ibid., 42, 1446-55 (1950). Latner, A. L.,and Slack, E. B., Nature, 165,530-1 (1950). Lindgren. H.O.,U. S. Patent 2,478,971(Aug. 16,1949). Lipecomb, G., U. S. Patent 2,506,882(May 9,1950). Loewe, H., PkurmaZie, 4, 416-24 (1949). Lundal, I. J., U. 8.Patent 2,485,209(Oct. 18, 1949). MacInnes, D.A,, and Ray, B. R., J . Am. C h m . Soc., 71,2987-92 (1949).
Applications of Centrifugal Equipment Materials Separated Type of Unit Diammonium phosphate crystals Perf orate basket KCI and KISO~crystals Bird continuous BaCh Mgsor, Fe “4)2, Sod, Perforate basket KIbc, NHnCsHrS,brH, CuCNS Worts Ground beans Intermediates Various colloida Dextrose n:i De Lava1 F-Actomyoin Ultracentrifuge Lard Sharples tubular Tubular unit Oil Melamine crystals Perforate basket Forei n material from paper s t ock Hydroclone Dirt Jrom paper stock Tangential injector Trinttrobenzene Perforate basket
Table Manufacturing Procass Diammonium phosphate Potassium salts Reagent grade chemicals
Edible oils F-Actomyoinn Lard Margarine Melamine Pawr Paper Phloroglucinol Phenol Phenol recovery Proteina Sugar
Wool scouring a Not a commercial operation.
Bird Continuous Perforate basket Uftracentrtfu a1 Perforate bastet
.........
Phloroglucinol Sodium sulfate crystals Sodium phenolate Protein muscle Sugar
Grease
”
a spring for adjusting the belt tension on the Merco centrifuge (9) (Figure 2); a new method of manufacturing the drip pan for the Sharples centrifuges (IS); and removable screen plates and wear plates for the McNally-Carpenter centrifugal dryer (8). RECENT PATENTS
The recent patents issued are tabulated below: Centrifugal apparatus for aerosol production (31 ) Centrifugal concentration of latex ( 3 7 ) Centrifugal foam breaker (66) Centrifugal ore concentrates (19) Centrifugal separator of entrained oil from steam (18) Centrifugal separator for sour cream products (4.4) Centrifuge for clarification of wines and juices (36) Centrifuge for extruding fibers, particularly glass fibers (56) Centrifuge for the purification of liquids (78) Centrifuge for washing paper pulp (4%) Combined centrifugal and vacuum dryer of pharmaceutical preparations (15 ) Continuous operation centrifuge ( 7 3 ) Extracting oil, etc., from soybeans ($4) Foam breaker in the form of a basket centrifuge (28) Multistage separation of starch tailings ( 7 4 ) Purifying sugar juice ( 4 1 ) Separation of aconitic acid from moIasses (3) Vertical continuous centrifuge ( 7 7 ) LITERATURE CITED
1
(1) Adler, F. T.,and Blanchard, C. H., J . Phys. & Colloid Chem., 53,803-10 (1949). (2) Amberson, W. R., et al., J. Biol. Chem., 181,405-13 (1949). (3) Ambler, J. A,, and Roberts, E. J., U. S. Patent 2,481,557(Sept. 13, 1949). (4) Anon., Chem. Eng., 57,No. I, 168-71 (1950). (5) Ibid., No. 6,p. 146. (6) Anon., Chem. Inds., 64. 926-9 (1949). (7) Ibid. 66. 266 (1950). i8) Ibid.: p. 580. (9) Anon., Machine Design, 22,No.5,106 (1950). (10)Anon., Marine Eng., 54,No.5, 66 (1949). (11) Anon., Modern Plastics, 26,No. 4, 115 (1948). (12) Anon., Product Eng., 21, No. 1, 100 (1950). (13) Armstrong, T. R., private communication (October 1950). (14) Beyerle, K.,et al., Chem. Ing. Tech., 21,331-4 (1949). (15) Bierwirth, R. A., U. S. Patent 2,512,604(June 27, 1950). (16) Brown, et al., “Unit Operations,” pp. 258-68, New York, John Wiley & Sons, 1950. (17) Burak, N., and Storrow, J. A,, J . SOC.Chem. Ind. ( L d o n ) , 69,8-13 (1950). (18) Campbell, J. A., U. S. Patent 2,511,967(June 20, 1950). (19) Chisholm, G. G., Ibid., 2,502,704(April 4, 1950). (20) Deatherage, F. E., FoodZnds., 21, 1749-52, 1894-5 (1949). \ -
S?
I
Figure 2.
N e w Design of Merco Centrifuge
INDUSTRIAL AND ENGINEERING CHEMISTRY
58 (46) (47) (48) (49) (50) (51) (52) (53) (54) (55) (56) (57) (58)
Mack, K. A., private communication (October 1950). Maloney, J. O., IND.E N G .CHEM.,38, 24-5, 37 (1946). Ibid., Ibid., Ibid., Ibid.,
39, 16, 35 (1947). 40, 8-9 (1948). 41, 19-21 (1949). 42, 25-6 (1950).
Meystre, F. J., Jr., private communication (October 1950). Miessner, H., Chemie Ing. Tech., 21, 409-12 (1949). Nichols, J. B., and Bailey, E. D., in “Technique of Organic Chemistry,” 2nd ed., Vol. I, pp. 621-730, New York, Interscience Publishers, 1949. Olive, T. R., Chem. Eng., 56, No. 10, 112-13 (1949). Peyches, I., U. S. Patent 2,497,369 (Feb. 14, 1950). Pomeroy, H. H., private communication (October 1950). Reed, A. E., and Gillespie, W. F., Tech. Assoc. Pulp Paper Ind.,
32,529-34 (1949). (59) Reynolds, V. L., Ibid., 32, 454, 457 (1949). (60) Richardson, A. C., and Lyons, 0. R., Mining Eng., 187, 381-4 (1950). (61) Rogge, R. H., IND.E N G .CHEM.,41, 2070-5 (1949). (62) Rometsch, W. H., private communication (October 1950). (63) Rostripenko, I. A., Sakharnaya Prom., 23, No. 2, 32-3 (1949).
Vol. 43, No. 1
(64) (65) (66) (67) (68) (69)
Sackett, E. L. H., Eng. Mining J., 151, No. 4, 79-80 (1950). Seidel, K., Brauwelt, 4, 53-6 (1949). Sharples, L. P., U. S. Patent 2,489,678 (Nov. 29, 1949). Shearon, W. H., Jr., IND.E K G .C m x , 42, 1266-78 (1950). Smith, J. C., Chem. Inds., 65, 357-64 (1949). Snellman, 0.. and Erodos, T., Biochim. et Biophys. Acta, 3,
(70) (71) (72) (73) (74) (75) (76) (77) (78) (79)
Sokolov, V. I., Kolloid. Zhur. 9, 447-9 (1947).
523-6 (1949).
Sokolov, V. I . , Zawdskaya Lab., 14, 4 3 5 4 0 (1948). Stocking, C. R., and Weier, T. E . , Science, 111, 520 (1950). Stolbovoi, F. K., Russ. Patent 69,430 (Oct. 31, 1947). Strezynski, G. J., U. S. Patent 2,488,747 (Nov. 22, 1949). Thompson, H. L., et al., IND. E K G .CHEM.,42, 2176-82 (1950). Thompson, N. B., Sewage and Ind. Wastes, 22, 205-6 (1950). Vidman, A. I . , Russ. Patent 69,996 (Dec. 31, 1947). Wieland, C. W., Swiss Patent 238,684 (Kov. 16, 1945). White, E . D., Food Inds., 22, 1538-41 (1950). (80) White, W.A., Paper Trade J., 130, KO.4, 76, 78-83 (1950). (81) Wilcox, A. C., University of Kansas, thesis, 1947. (82) Zhitomirskaya, E. Z., and Meitina, V. A., Stekol’naya i Keram. Prom., 6, No. 8 , 15-16 (1949). RECEIVED October 24, 1950.
RYSTALLIZATION C. S. GROVE, JR., SYRACUSE
AND
J. B. GRAY
UNIVERSITY, EAST SYRACUSE, N. Y.
Few advances in theoretical correlation of crystallization phenomena have been reported during the past year. Emphasis has been placed on the effects of additions, as chemical ions, or physical treatments on both rate of crystallization and crystal habit. M u c h work has been reported on oriented growth of crystals on other crystalline or amorphous surfaces. A new field of application of crystallization has been opened up b y the use of crystalline complexes of urea and straight-chain hydrocarbons to separate straight-chain from branched and cyclic hydrocarbons. Processes for growing piezoelectric crystals have been improved. When ethylene glycol and ethyl alcohol are added to aqueous solutions of sodium sulfate, the deposition of solids on heating surfaces due to a lower solubility in water at higher temperature is avoided.
c
RYSTALLIZATION processes have continued to receive increased study and development. There have been many investigations reported on the factors affecting the growth of crystals and the mechanisms involved in this growth. New techniques and improvements in industrial processes have been described. However, a satisfactory broad theoretical treatment of crystallization has not been reported. N U C L E A T I O N AND RATE OF G R O W T H The difficulty in formulating a complete theory describing the rates of formation of nuclei and growth of crystals is well expressed by Kirk and Othmer (47), who state:
The mechanism of this process is very complex, as it involves the phenomena of diffusion, formation of nuclei, and crystal growth, all of which can take place a t the same time. No exact numerical calculations of the rates of any of these can be made at the present time so that, as a unit operation, crystallization is still highly empirfical in its methods. Because of this lack of any precise design calculations, the types of crystallizers have been numerous. T o add to the designer’s difficulty, it is frequently necessary t o produce crystals of a given shape, size, uniformity, and state of agglomeration as well as purity. However, the current status of crystallization theory and practice is summarized in some detail by these authors. Brown (IO) has pointed out that the problems concerning crystallization which are most frequently encountered deal with yields, purity, energy requirements, shape, size, and uniformity of the crystalline product, and rate of production of the desired crystals. Perry (61) has summarized in detail crystallization
theory and practice. It is stated that new nuclei may originate in situ in one or more of the following ways: 1. By spontaneous n u c l e a t i o n from unseeded solution 2. By attrition of existing crystals 3. By mechanical impact 4. By formation of new crystals because of the inoculating influence of crystals already present 5. BY nucleation in restricting zones c a k e d by local variations in th; concentration of the solution
Umstatter and Hansen-Dannenitz (86) discuss the kinetics of precrystalline phases in liquids. They state that the inner friction of liquids is caused by the dispersion of transverse shearing waves propagating perpendicular to the gliding planes. The damping of these vibrations is proportional to the viscosity. In case of nonperiodic damping the viscosity becomes infinitely high a t certain phases of the vibrations, and at these pointscrystal nuclei form. This indicates that the future crystal systems are already preformed in the liquids, which are accordingly precrystalline systems rather than systems of complete disorder. Becker (4) has discussed the kinetics of the formation of nuclei on the basis of the statistical theory of condensation. Turnbull and Fisher (84) have derived an expression for the absolute rate of nucleation in condensed systems on the basis of a nucleation theory. Bransom, Dunning, and Millard (9) further amplify the theories of crystallization. Van Hook and Bruno (88) have reported on nucleation and crystal growth in sucrose solutions. The beginning of crystalliaation in sirups may be represented by an equation of the form:
(0 -a)t = constant where 0 is the supersaturation, t is the time, and a is a constant, It was found that nucleation was not affected by stirring below a certain supersaturation; but, above this supersaturation, the higher the concentration and the faster the stirring, the more rapidly nucleation took place. Crystallization from nonaqueous solutions has been studied by Chatterji and Bose (WO), whose work shows that nonaqueous
