JANUARY 1957
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CHEMISTRY AND CHEMICAL ENGINEERING IN THEORY AND PRACTICE The w h y , what, and significance of technical articles in this issue. Clip these Briefs for ready reference and easy filing on a 3 X 5 or other suitable card
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Ind.
Eng. C h e m . 49, 11 (1957
Tracer Studies
STAFF-INDUSTRY COLLABORATIVE REPORT
Catalyst circulation patterns have been determined in three commercial catalytic cracking units, using techniques developed for tagging cracking catalyst with radioactive isotopes, rapid injection and sampling of catalyst, and measurement of low level radioactivity. The loss rate of fresh catalyst from commercial catalytic cracking units can be determined by use of radioactively tagged catalyst. Helium tracer has been used to study gas mixing characteristics in the regenerator vessel of a commercial unit. Although residence time distribution in the dense phase resembles that of a well-mixed vessel, distribution of gas in this phase is not completely uniform. This points to the need for simultaneous residence time and distribution studies. A model has been developed to account for the influence of disengaging zone on time-concentration measurements. E. S I N G E R , D. B. T O D D , V . P. G U I N N , W . B. W I L S O N , A . E. H A N D L O S , R. W . K U N S T M A N , a n d D. O. S C H I S S L E R Shell D e v e l o p m e n t C o . , Emeryville, C a l i f .
I n d . E n g . C h e m . 49, 1 (1957)
Uranium from Gold Wastes Production of uranium oxide in the free world may reach 30,000 tons per annum within a few years. Over $180,000,000 have been invested in uranium plants of South Africa to recover the uranium in effluent slime from gold reduction plants. Daggafontein Mines Ltd., first company in the Anglo American group to produce uranium from gold wastes, is one of the largest uranium producers in South Africa. In processing low grade uranium ores, application of ion exchange is used to recover uranium from an acid leach solution. At Daggafontein's plant in the Transvaal, uranium is absorbed from a pure solution of uranyl sulfate containing an excess of free sulfuric acid when passed through a strong base ion exchange resin. Manganese dioxide is used as an oxidant in the Pachuca tanks where uranium is dissolved in sulfuric acid. Most plants in South Africa have facilities for recovery and reuse of manganese. The process removes iron, aluminum, and silica and precipitates manganese hydroxide from the separated solution with lime slurry. WILLIAM Q. HULL and EWEN T. PINKNEY
I n d . E n g . C h e m . 49, 31 (1957)
Sulfonation with Sulfur Trioxide Petroleum Lubricant Raffinâtes Production of oil-soluble sulfonates by sulfonation of petroleum lubricant raffinâtes has grown steadily. A study has been made of the preparation of such sulfonates from representative American stocks, using the standard reagent, oleum, in comparison with sulfur trioxide, which is now commercially available. Sulfur trioxide, applied as air-diluted vapor, gives a higher yield of sulfonate and a lower yield of sludge than oleum, with best yields resulting from the application of a given weight of reagent in several successive portions. Product sulfonate colors vary from light to dark and sludge consistencies from mobile to thick, depending on the oil. Results indicate that sulfur trioxide is more efficient than oleum for preparing petroleum sulfonates. E V E R E T T E. G I L B E R T a n d B E N J A M I N V E L D H U I S G e n e r a l C h e m i c a l D i v i s i o n , A l l i e d C h e m i c a l &. Dye C o r p . , Morristown, N. J .
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Ind.
Eng. C h e m . 49, 39 (1957)
Dealkylation of Ethylbenzene This exploratory investigation shows that ethylbenzene can be dealkylated over equilibrium microspheroidal cracking catalyst to produce lower aromatics. The yield of Ce and C; aromatics is a linear function of space velocity. The use of steam as a diluent reduces coke make and results in a larger proportion of ethylene in the gas produced. At 1085 ° F., 0.6 l.h.s.v., and 0.6 water/oil mole ratio, 32 volume % of the ethylbenzene is converted to yield, on a charge basis, 18.8 volume % benzene and 2.2 volume % toluene. This represents a combined conversion efficiency to benzene and toluene of 89 mole %. MAXWELL NAGER Shell Oil Co., Houston, Tex.
Eng. C h e m . 49. 49 (1957)
Sulfur Vulcanization of Vinyl-Substituted Polysiloxanes This work was undertaken to define the ingredients and conditions necessary for vulcanizing a polysiloxane with a sulfur-vulcanization system. Olefinic groups such as vinyl groups attached to silicon are necessary for sulfur vulcanization in this polymeric system. The rate of vulcanization and the ultimate state of cure are dependent upon the vinyl content in the polymer. Vulcanization rates are dependent upon the accelerator used. Strong organic bases, guanidines, and thiuram disulfides are the most active accelerators. Zinc oxide and organic acids inhibit and retard vulcanization in this polysiloxane system. The temperature coefficients for rate of vulcanization and Arrhenius activation energies are similar to values obtained in other polymeric systems. The reaction steps of vulcanization are necessarily different from those postulated for polyisoprene. K. E. POLMANTEER and R. J . KOCH Dow Corning Corp., Midland, Mich.
Ind.
E n g . C h e m . 49, 42 (1957)
Direct Mercuration of Benzene Mercuratïon of aromatic compounds is a unit process which has received relatively little study. The mercuration of benzene is the reaction carried out on the largest industrial scale. A unit process study of the mercuration of benzene has shown the effect of the process variables—temperature, time, and mole ratios of benzene and acetic acid to mercury—for the uncatalyzed reaction. Both the mono- and dimercuration reactions are reversible. Dimercurate formation can be kept at a minimum by proper control of process variables. Dimercurate can be separated from the solution of mercurated benzene and cycled in the process.
Ind.
Eng. C h e m . 49, 55 (1957)
Reactions in Sodium Hydroxide-Nickel System Reactions between sodium hydroxide and nickel have b e e n studied in vacuum at temperatures near 1000° C. Products identified are hydrogen, water, sodium oxide, nickel oxide, sodium nickelate(II), and sodium; reactions for their formation are proposed. It is concluded that all reactions are driven by the removal of a gaseous product and that in a closed system no net reaction would occur. D. M. MATHEWS and R. F. KRUH University of Arkansas, Fayetteville, Ark.
K. SEWALL McMAHON and KENNETH A. KOBE University of Texas, Austin, Tex.
Ind.
Ind.
E n g . C h e m . 49, 46 (1957)
Methylstyrene—A Case Study in Spent Acid Catalyst Treatment A new process for manufacturing methylstyrene produces a polymer having desirable properties, but its wastes containing mercury and sulfuric acid entail disposal problems. By hydrolyzing and stripping such waste with superheated steam, mercury and toluene may be recovered in high yield, and the stripped sulfuric acid is sufficiently concentrated to be used in fertilizer manufacture. Details of this novel procedure are given with a description of a projected commercial-scale waste acid treatment plant. NATHAN FEDERGREEN and ARTHUR J. WEINBERGER Stamford Research Laboratories, American Cyanamid Co., Stamford, Conn.
Eng. C h e m . 49, 59 (1957)
Uranium-Aluminum Alloy Dissolution The dissolution of uranium-aluminum alloys as a step in the recovery of uranium was studied using boiling aqueous solutions of nitric acid, which contained mercuric nitrate as a catalyst, and of sodium hydroxide as dissolvents. The alkaline system is shown to conform to heterogeneous first-order kinetics. The acidic system is shown to be kinetically more complex and is explained in terms of competing reactions. Extruded metal dissolved much more rapidly then cast metal in the acid system but at about the same rate in the alkaline system. No significant difference in dissolution rates was found between aluminum and aluminum-uranium alloys containing up to 15% uranium. R. G. WYMER and R. E. BLANCO Oak Ridge National Laboratory, Oak Ridge, Tenn.
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Ind.
E n g . C h e m . 49, 62 (1957)
Magnetic Conversion of Iron Ores Fluidized Solids Technique
Ind.
One of the problems confronting the iron ore industry has b e e n utilization of low grade ores. Among the foremost of the various methods proposed for this beneficiation a n d u p g r a d i n g is the reduction of low grade a n d now useless hematite or taconite ore to magnetite. By magnetic conver sion t h e r e d u c e d ore is converted to an ideal blast furnace or open hearth feed. As a result of experimental laboratory work, a fluidized reduction system adaptable to a n u m b e r of reducing gases has b e e n developed a n d the flowsheet of a typical commercial installation completed. T h e economics of such a system are favorable with reduction costs estimated at $0.70 p e r long ton of feed. T h e next step in the develop ment program is the installation of a prototype unit for pilot plant studies in cooperation with an iron-ore producer.
Eng. C h e m . 49, 104 (1957)
Automatic Computation of Antoine Equation Constants Caproic and Caprylic Acids and Methyl Esters T h e method of Taylor for expressing vapor p r e s s u r e t e m p e r a t u r e data b y obtaining constants for the Antoine equation has been modified to permit automatic computa tion of these constants. T h e method may be readily applied to obtain the best constants for any substance for which data are available. New vapor pressure—temperature data were obtained b y this method on highly purified samples of π-caproic acid, n-caprylic acid, methyl caproate, a n d methyl caprylate in the course of the present work. A R T H U R ROSE, J E R R Y A. A C C I A R R I , R. C U R T I S J O H N S O N , and W . W . S A N D E R S Pennsylvania S t a t e University, University P a r k , Pa.
ROBERT J . PRIESTLEY Dorr-Oliver I n c . , S t a m f o r d , C o n n .
Ind.
Eng. C h e m . 49, 65 (1957)
Water Resistance in Floor Wax in Relation to Amine Content An important property of floor wax emulsions is the rate a n d extent of development of water resistance. It has been generally assumed t h a t water resistance of t h e resultant films develops either from evaporation of the amine emul sifying agent or chemical change in the emulsifier. Emulsions were p r e p a r e d with a variety of amines. A study of the films was made (by nonaqueous titrimetry) d u r i n g drying on glass. All the amines volatilized to a significant extent, b u t this was not directly related to t h e volatility of the free amine. After 19 days 42 to 5 4 % of the amine was no longer in the film; exceptions were morpholine (90% lost) and 2-amino-2-methyl-l-propanol ( 2 8 % lost). Loss of amine from t h e film is not t h e primary cause for the development of water resistance, since all the films did not develop water resistance. No chemical change in t h e emulsifier was noted. J O H N A . F R U M P and J O H N A. R I D D I C K C o m m e r c i a l Solvents C o r p . , T e r r e H a u t e , I n d .
Ind.
Packed Thermal Diffusion Columns—Effect of Changes in Annular Spacing and Packing Density T h e effect of varying a n n u l a r spacing and packing dens ity has been studied for the batch separation of organic liquids in concentric tube columns packed with glass wool. T h e test mixture used was a 50 volume % mixture of the cis- a n d r r a n s - d e c a h y d r o n a p h t h a l e n e s . T h e mixture is shown to be a good test mixture for column evaluation in that it separates in a regular m a n n e r a n d is difficult to separate completely. T h e comparative ease with which mixtures of n-hexadecane and decahydronaphthalene or n hexadecane and methylnaphthalene are separated is il lustrated. A complex relation is shown between percentage separation a n d a n n u l a r spacing, whereas, within limits, a direct relation is found between percentage separation a n d packing density. L L O Y D J . S U L L I V A N , T H O M A S C. R U P P E L , and C H A R L E S B. W I L L I N G H A M M e l l o n I n s t i t u t e , P i t t s b u r g h , Pa.
Ind. Ind.
Eng. C h e m . 49, 68 (1957)
Cellulose Derivatives T h e various derivatives of cellulose have widely diversi fied industrial applications because of their interesting a n d u n u s u a l solubility properties. Methods of preparation of cellulose phenylthiourethane are discussed in this series of seven articles, as well as properties of a fiber p r e p a r e d from this derivative. Farhydrolyzed cellulose acetates have properties different from those of the regular acetone-soluble acetates. One farhydrolyzed derivative has b e e n p r e p a r e d which contains 17% acetyl a n d is water-soluble. Phthalic acid esters can b e p r e p a r e d without the use of pyridine if acetic acid is substituted as solvent a n d sodium acetate as basic catalyst. A study of aqueous carboxymethyl cellulose solutions clarified Theological behavior of these derivatives. Viscosity-temperature relationship was also studied for CMC. Biological degradation studies indi cate that, for practical rot resistance, every anhydroglucose unit should have at least one substituent.
Eng. C h e m . 49, 110 (1957)
Eng. C h e m . 49, 114 (1957)
Heat-Transfer Studies Vertical Free Convection from an Isothermal Surface Local free convection from a vertical flat plate was in vestigated for no obstruction of the i n d u c e d vertical flow at .v (the vertical distance measured along the plate from the origin of the heated surface) equal to zero a n d an obstruc tion at χ equal to 0, 4, 8, a n d 16 inches. T h e local Nusselt n u m b e r was determined at values of χ ranging from 0.5 to 16.0 inches with t e m p e r a t u r e differences between the plate a n d t h e ambient air of 15 ° to 50 ° F. T h e resultant r a n g e in the product of the Grashoff a n d P r a n d t l moduli was 10 3 to 10». No difference was determined for heat transfer from the plate with a n d without the obstruction at χ equal to zero. T h e effect of the obstruction at 4, 8, a n d 16 inches was found to extend upstream—i.e., toward smaller values of χ—from the obstruction approximately two b o u n d a r y layer thicknesses. J. T . BEVANS University of C a l i f o r n i a , Berkeley 4, Calif.
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Ind.
Eng. Chem. 49, 120 (1957)
Generalized Correlation for Effect of Pressure A generalized correlation is submitted for the deviation at elevated pressure of the isobaric heat capacity of hydro carbons from the value for the ideal gas state. The curves are based on data calculated from the Bene dict-Webb-Rubin equation of state. Comparisons have been made with the correlations submitted by previous investigators, and relative accuracies have been discussed. A comparison with experimental data on heat capacity indi cates that the correlation is suitable for nonpolar gases. The procedure used in arriving at the present correlation is believed to yield a more accurate heat capacity correlation than those previously published. This conclusion is sup ported by available experimental data. ALVIM H. WEISS and JOSEPH JOFFE Newark College of Engineering, Newark, N. J .
Ind.
Eng. Chem. 49, 142 (1957)
Effect of Particle Size on Combustion of Uniform Suspensions The lean limit of flammability and the maximum pressure rise of nearly monodisperse clouds of Armowax particles in air have been determined. The maximum pressure reached during the constant volume combustion of suspensions composed of particles ranging from 10 to 90μ is inversely proportional to particle size. A maximum air-fuel ratio of 58:1 for the lean limit of flammability is obtained for suspen sions of 60-μ particles. Larger and smaller particles have lean limits of lower air-fuel ratio with values of 25:1 for both 10- and 90-μ sizes. No rich limit is evident within the range of mixture strengths tested. J. A. BROWNING, T. L. TYLER, and W. G. KRALL Dartmouth College, Hanover, Ν. Η.
Ind. Ind.
Eng Chem. 49, 125 (1957)
Correlating Vapor Pressures and Other Physical Properties A convenient, accurate method of applying a general equation for variations in vapor pressure and phenomena related to temperature is given, including constants for over 500 compounds and a nomogram for precise vapor pressure. Latent heat values are interrelated and deter minable at any pressure or temperature, from either the equation or nomogram. For other compounds, methods for determinining constants in the equation are described. The nomogram is useful for solubility of gases and liquids, adsorption, absorption, and other thermodynamic functions —e.g., vapor-pressure equilibrium, chemical reaction rates, equilibrium flash-vaporization values, or relative volatilities and activities. Such properties as heats of reaction, solu tion, vaporization, are also interrelated, and are usable in evaluating the other functions or determinable therefrom. DONALD F. OTHMER, PAUL M. MAURER, CHARLES J. M O D NARY, and RONALD C. KOWALSKI Polytechnic Institute of Brooklyn, Brooklyn, Ν. Υ. Ind.
Eng. Chem. 49, 148 (1957)
Rate of Steam-Carbon Reaction by a Falling Particle Method This work was undertaken to obtain kinetic data under the following conditions: temperature range, 1800° to 2500° F.; carbon particles size, 200- to 230-mesh; and sufficient excess of steam so that the change in the gas composition was negligible. Preheated carbon particles and steam flowed cocurrently through an externally heated tube. The carbon conversion was determined from the difference in weight of the entering and leaving carbon. The reaction rates were extrapolated to zero conversion. Two types of carbon were investigated—petroleum coke and electrode graphite. For both types of carbon, a surface or chemically controlled reaction rate is indicated because activation energies in the order of chemical reactions were obtained and because rectilinear correlations on an Arrhenius plot were obtained. However, the rates obtained for the two carbons were widely divergent, and the type of variation with burnoff for the two carbons was also different. JAMES A. DOTSON, JOHN H. HOLDEN, and WALTER A. KOEHLER Bureau of Mines, Morgantown, W. Va.
Eng. Chem. 49, 138 (1957)
Slurry and Suspension Transport The flow of non-Newtonian fluids in annular conduits is of interest to many industries dealing with the transport of suspensions and slurries. Since the flow of Newtonian fluids in annuli cannot be calculated accurately using circular pipe formulas, this limitation is assumed to apply to non-Newtonian flow. Many industrial slurries may be regarded as plastic fluids of the Bingham type. An equation for the laminar flow of a Bingham body in an annular conduit is developed which requires numerical methods for solution. An approximate equation is more convenient for practical application. Examples illustrate the numerical procedures for the exact solution and show the inaccuracies incurred by using approximate equations. Pressure versus flow curves and velocity profiles are plotted for a typical Bingham body and for a Newtonian fluid having the same viscosity flowing in an annular pipe. Turbulent flow is not considered, it being assumed that conventional formulas and friction factors are valid.
Ind.
Eng. Chem. 49, 155 (1957)
Theory of Thermal Diffusion under Linear Fluid Shear A mathematical theory of thermal diffusion under linear fluid shear is presented. The theory applies to all cases in which one wall of the thermal diffusion device moves uni formly with respect to the opposite wall. Equations for the steady state as well as for the approach to the steady state are derived under the condition that fluid motion due to natural convection and the variation of the "Soret constant" with concentration can be neglected. The results differ significantly in form from those derived by Debye for thermal diffusion under natural convection. JOHN H. RAMSER Research and Development Department, Atlantic Refining Co., Philadelphia, Pa.
WILLIAM M. LAIRD Gulf Research A. Development Co., Pittsburgh 30, Pa.
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