I&EC REPORTS A N D COMMENTS A close look at a dissolving gas bubble N e w hydrocarbon handbook from A.P.I.
I&EC Division symposium on dispersed systems
A MATTER OF REFINEMENT Analysis of convection efects in gasliquid dafusivity measurement technique boosts accuracy only slightly I n I&EC Reports and Comments, July 1967 [Vol. 59 ( 7 ) ,p. 121, we described a technique for the measurement of gas-liquid diffusion coefficients developed at Case Institute of Technology. The method involved the dissolution into a liquid of a gas originally present in a bubble held on a fiber, as well as measurement of the reduction in diameter of the bubble with time. This method is extremely promising as it comes much nearer to assuring a truly spherical bubble-on which analysis is basedthan other bubble dissolution methods where the bubble shape is distorted by its being held against a plane surface. Early results at Case Institute, reported in J . Phys. Chem. 71, 1123 (1967), showed that the method gave accurate results. The analysis assumed an isolated sphere in spherically symmetrical conditions. Although the Case technique managed to attain a nearly spherical bubble, it is clear that as the bubble shrinks, its center is not fixed in space, but travels toward the fiber-see sketch. This tendency for the assumption of spherical symmetry to be destroyed was neglected in the Case Institute work, but is probably unimportant unless the bubble dissolves very quickly. This is only one of a number of effects that, for the sake of simplicity and because they were considered negligible, were omitted from the simple analysis of diffusion from a bubble to a liquid. The analysis also neglected convection effects which occur because of the change in volume of the liquid which dissolves the gas from the 6
bubble. L. E. Johns, Jr., of the University of Florida has redetermined approximate stationary solutions to the spherical bubble dissolution system and has taken into account convective effects due to the density difference between gas-rich liquid and pure liquid. [ J . Phys. Chem. 71,4566 (1967)l. Johns compared the values of diffusivity determined with and without considering convection. He found that the error involved in neglecting convection is very smallabout 1% for air-water and 5% for carbon dioxide-water. I t seems that very little is to be gained by including the convection term in the analysis of the dissolution of sparingly soluble gas bubbles, but that a small correction is justified in the case of soluble gas bubbles. There are many aspects to the refinement of a technique for the determination of a physical property; in this case the originators of the technique consider that the most important gains are to be made in the refinement of the experimental apparatus, Attention to individual assumptions and simplifications made in the theoretical analysis are likely to provide further refinements, just as did Johns’s questioning of the neg-
Projiles of dissolving gas bubble
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
lected convection term. One can imagine a long string of refinements to the basic technique, each increment making a slightly smaller contribution than the last. But the question that engineers might ask themselves is: Under what conditions should refinement be undertaken, and, just as important, when should it be discontinued? Readers interested in the dissolving of gas bubbles in a liquid would probably also be interested in a paper by M. Cable of the University of Sheffield, England, in Chem. Eng. Sci. 22, 1393 (1967) in which theoretical and experimental dissolution are discussed.
HYDROCARBON DATA BOOK A.P.I. publication assembles data and correlations for pure and mixed hydrocarbons in convenient handbook form Statistics show that when a chemist or engineer needs a specific piece of information-a physical property value, for example-he almost always looks first in a data book or handbook. Only when unsuccessful in finding what he needs there will he start searching textbooks and the literature, or plunge head first into the voluminous indexes of Chemical Abstracts. I t follows, therefore, that a stock of basic data books can be the technical man’s best weapon in his constant fight with his problems. Examination of any busy engineer’s shelf will testify to his reliance on them. However, due to the prevailing climate in which the generation of new data is judged to be a more worthwhile activity than organizing old data in a usable manner, the number of really valuable data books is rather small.
A welcome addition to the ranks of handy handbooks has recently been published by the American Petroleum Institute. Entitled “Technical Data Book-Petroleum Refining,” the book is an 800-page compendium of data and correlations of data for pure and mixed hydrocarbons. I t is the result of five years of labor at Pennsylvania State University Petroleum Refining Laboratory and was sponsored by $340,000 from the A.P.I. Professors M . R. Fenske, W. G. Braun, and W. H. Thompson directed the project under the guidance and review of two A.P.I. committees representing major contracting and petroleum companies. T h e Penn State staff set out to glean basic data on hydrocarbons and to gather and check the accuracy
of existing correlations, improving them when necessary. They were given access to private company data books and other proprietary information developed by the companies represented on the guiding committee. The Data Book thus contains data and correlations previously kept under lock and key and makes them universally available. T h e correlations were checked against available data through the use of a large number of computer programs before the recommended correlations were chosen. This procedure differs somewhat from the general approach taken in the A.1.Ch.E. physical property estimation system (described by R. E. Heitman and G. H. Harris in I&EC, February 1968), in that the latter system considers all available corre-
lations and chooses the one that gives a minimum error estimate of the required property. The Data Book contains 14 chapters: General Data; Characterization of Hydrocarbons; ASTM Distillation, True Boiling Point Distillation, and Equilibrium Flash Vaporization Relationships for Petroleum Critical Properties ; Fractions ; Vapor Pressure; Density; Thermal Properties ; Vapor-Liquid Equilibrium K-Values; Phase Equilibria in Hydrocarbon-Nonhydrocarbon Systems; Surface Tension ; Viscosity; Thermal Conductivity; Diffusivity; Combustion. Pure hydrocarbons, mixtures of known composition, and petroleum fractions are treated separately. I n most cases the gaseous and liquid states are given separate treatment.
D I V I S I O N OF INDUSTRIAL AND ENGINEERING C H E M I S T R Y SYMPOSIA A T T H E ACS NATIONAL M E E T I N G , SAN FRANCISCO, APRIL 1-5, 1968 T h e Division has arranged a technical program of wide scope and timely technical interest for the San Francisco meeting. Two symposia will be conducted simultaneously from Monday morning through Thursday afternoon with one symposium being con-
cluded Friday morning. The symposium schedule is outlined to help you plan your week to gain the most information in your interest area from these technical sessions. Don’t miss these outstanding sessions.
i. Polymerization a n d Polycondensation Processes N. Platzer, Chairman Monday, April 1 through Friday morning, April 5 These 9 sessions cover a wide interest range including free radical stereospecific and radiation induced polymerization, depolymerization. 2. Prediction of Transport Properties Hsien Wen Hsu, Chairman Monday (morning and afternoon), April 1, 1968 The papers in these two sessions will address themselves to the prediction and measurement of transport properties in gases and liquids. 3. Optimizing Chemical Processes John R . Ferron, Chairman Tuesday (morning), April 2, 1968 The papers in this session outline the techniques and calculation procedures for optimizing single-stage and multistage processes.
4. The Innovation Process i n Industry
E. F. Engles, Chairman Tuesday (afternoon) April 2, 1968 This session, joint with the Division of Chemical Marketing and Economics, points out how to utilize the innovative and inventive process in the chemical industry. A panel discussion follows the session. 5.
New Reactions in Chemical Processing J . D.Idol, J r . Chairman Wednesday (morning and afternoon) April 3,1968 Specific examples of several new catalytic and noncatalytic chemical processes are given in these two sessions.
6. Applied Statistics for the Chemical Process Industries
Robert A . Stowe, Chairman These two sessions, joint with the Chemical Division, American Society of Quality Control, give examples of the application of statistical techniques in the chemical industry.
VOL. 6 0
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7
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Circle No. 8 on Readers’ Service Card
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
T h e A.P.I. claims that the petroleum industry could save $2 million per year if better enthalpy data for heat exchanger design were available. The outlay of $125 required to purchase the Data Book seems a small price to pay for better design bases. T h e Technical Data Book is available from the Division of Refining, American Petroleum Institute, 1271 Avenue of the Americas, New York, A-. Y . 10020. Copies of the 13 documentation reports and four bibliographies from which the Data Book was compiled are also available for $125 and $5, respectively.
CONTROL OF DISPERSE PARTICULATE SYSTEMS “What’s going on in there?’’ is the $64 question being asked by engineers and scientists trying to frame a mathematical description of disperse systems. Some 100 of them gathered a t the 34th Annual Chemical Engineering Symposium, sponsored by the Division of Industrial and Engineering Chemistry held a t MIT, Dec. 11, 12, 1967. The disperse systems discussed were diverse, including such processes as crystallization, emulsifying, grinding, dispersion and coalescence, cell growth, and other biochemical, chemical, and physical processes. Disperse systems are among the most complex physical problems that engineers must face. O u r engineering approaches today still tend to be primarily macroscopically descriptive, reflecting a rather refined ignorance about what is going on within. But recent work, made worthwhile by the availability of computer time and speed, is focused on accurate mathematical descriptions of the systems and processes a t a microscopic-and even molecular-level. At first glance, the mathematical models presented for different systems appear to be quite different from each other in nature. As one’s
I&EC REPORTS
insight develops, however, it becomes increasingly clear that these models are very similar. There are three general types of equations : 1. Differential
Rgv, -
= P(X,O)
i
ct,j)st
f
k
ck,tsk
These equations develop into mathematical monstrosities and include many more terms than those above. Despite today’s computing competence, they cannot be solved analytically. Therefore much of the symposium was centered on what simplifying assumptions to make so that the mathematics would become more tractable. And much of the argument and stimulation of the meeting stemmed from differences of
2. Integral %t>
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CORRECTION (23) Guinier, A,, Fournet, G. L., “Small Angle Scattering of XRays,” Wiley, New York, 1955. (36) Lunsford, J. H., Jayne, J. P., J. Chem. Phys. 44, 1487 (1966). (37) O’Reilly, D. E., MacIver, D. S., J. Phys. Chem. 66, 276 (1962). (39) Selwood, P. W., “Magnetochemistry,” 2nd ed., p. 374, Interscience, New York, 1956. (39A) Turkevich, J., Noxaki, F., Stamires, D., Proc. 3rd Intern. Congr. Catalysis, Amsterdam, 586 (1965). (44) Sachtler, W. M. I%, de Boer, J. H., Proc. 3rd Intern. Congr. Catalysis, Amsterdam 252 (1965).
Several errors were made in the publication of the paper by C. F. Cullis in IND. ENC. CHEM59 (12), 18 (December 1967). The corrections listed below should be noted. 1. P. 19, column 2, line 6, napthalene should be naphthalene, line 11, Phenol not ital. 2. P. 20, Table I, column 1, tert-2Butene should be trans-2-Butene 2-Pentene (cis and tert) should be 2-Pentene (cis and trans) 3. P. 20, first equation, the arrow should be deleted after D 4. P. 23, column one, 3 lines from bottom should read: thus, subgroup B oxides.. . . 5. P. 24, Figure 3, From ref. 16 should read From ref. 9 6. P. 27, column one, last two equations should read as follows:
.
0-
I (CHJzC -CHCH, I
P-
(CH&C-CHCHs
-e
0.
I
(CH&C-
CHCH, closurr
0.
0
(CH3),CL\CHCH,
I
(CH3),C-CHCH,
I 7. The references listed below should be corrected as listed: ( 5 ) Blyholder, G., Neff, L. D., J. Catalysis 2, 138 (1963). (12) Cossee, P., van Reijen, L. L., Proc. 2nd Intern. Congr. Catalysis, Paris, 1679 (1961 ). (15) Lippens, B. C., Linsen, B. G., de Boer, J. H., J.Catalysis 3, 32 (1964).
\H shift&
(CHJZCH-COCHS
(49) Sixma, F. L. J., Duynstee, E. F. J., Hennekens, J. L. J. P., Rec. Trav. Chem. 82, 901 (1951). (51) Suhrmann, R., Wedler, G., J. Catalysis I, 208 (1962). (56) Wheeler, A., “Catalysis,” P. H. Emmett, Ed., Vol. 2, p. 105, Reinhold, New York, 1955.
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Circle No. 13 on Readers’ Service Card
VOL 60
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I&EC REPORTS
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opinion concerning the mathematical and/or physical validity of the simplifying assumption. One can look for the literature in the near future to be aimed at making some order out of these different mathematics. The engineer who ties these complex mathematical models to a physical and chemical understanding of disperse phenomena will make a most worthwhile contribution. I t certainly has not yet been made. What does all this mean to the practicing chemical engineer? I t means that, when his crystallizer, grinder, fermenter, etc., go out of whack, he still must draw on his gut feeling to put them back on line. But, deep down in his sophisticated mind he can draw solace from the knowledge that his colleagues back on the computer are making real progress in fundamental understanding of these valuable processes. Little profit will result in the short term from this understanding of his work, but there is no doubt about the long-range profitability of a closer control over the behavior of disperse, particulate systems.
HYDROGEN PEROXIDE PREPARATION A new method for the preparation of hydrogen peroxide from its constituent elements has been disclosed in U.S. Patent 3,361,533 issued to I.C.I. Ltd. The invention claimed involves contacting hydrogen and oxygen with a solid catalyst in the liquid phase in the presence of water, an acid, and a nonacidic oxygen-containing organic compound. The acids giving the best results are HC1 and HzS04 and lower aliphatic alcohols and ketones are the preferred organic compounds. The presence of an acid radical other than that provided by the acid used is also needed.
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
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