Showing papers in "Canadian Journal of Chemical Engineering in 1963"

The gravity approach and coalescence of fluid drops at liquid interfaces

Abstract: The rate of thinning of the liquid film trapped between a fluid drop and a liquid interface and the subsequent coalescence of the drop were investigated using an interferometric method The rate of film thinning for small drops was in good agreement over a narrow range of film thickness with two previously proposed models The rate was greater than predicted when the film thickness was less than 02 μ presumably because of movement of the interfaces The minimum thickness in the film at rupture was usually less than 500 A for drop diameters up to 2500 μ The seemingly anomalous behavior of drops previously observed in a partial coalescence series resulted from uneven film thinning with larger drops Partial coalescence between finite drops was investigated briefly; no secondary drop was produced when the drop diameter ratio was less than about 35 Une etude a l'aide de methode interferometrique a ete entreprise sur le taux de decroissance d'un film liquide entourant une goutte de fluide a l'interface immiscible du liquide et du fluide, jusqu'a coalescence de la goutte Ce taux de decroissance est en accord pour les gouttelettes avec deux modeles precedents pour une region restreinte d'epaisseur de film Le taux est superieur a ceux predits pour une epaisseur de film inferieure a 02 microns possiblement cause par la mobilite des interfaces L'epaisseur minimum du film etait normallement moins de 500 Angstroms a la rupture pour des gouttelettes de dimensions jusqu'a 2500 microns Le comportement anormal note precedemment pour les gouttes en coalescence partielle a ete cause par la decroissance inegale du film avec les gouttes les plus grosses La coalescence partielle entre des gouttes a ete succinctement etudiee, aucune goutte secondaire n'est produite lorsque le rapport du diametre des gouttes est inferieur a environ 35

Kinetic studies on the thermal decomposition of calcium carbonate

Abstract: Kinetic studies have been made of the thermal decomposition of precipitated calcium carbonate, powdered calcite, and regular fragments of calcite crystals. The powdered materials were examined in the form of pellets, which were prepared by compacting the powder to about 70% of its theoretical density. The work was done at one atmosphere of pressure in a flow of air containing various amounts of carbon dioxide. It was observed that the decomposition of the pellets, which were prepared in a variety of shapes, was characterized by the same advancing interface mechanism as that observed for single specimens of crystal fragments. When the rates of decomposition were normalized for the change in of interfacial area accompanying decomposition, it was possible to correlate the observed rates of decomposition for a variety of pellet shapes, and to relate these rates, as a function of particle size and pellet roughness, to the rates of decomposition of large fragments of calcite crystals. The activation energy for the decomposition reaction was found to be 40.6 kcal./mole. At a constant temperature, the decrease in reaction rate with increasing carbon dioxide pressure was found to be proportional to the difference between the equilibrium dissociation pressure and the back pressure of carbon dioxide. A reaction mechanism based on diffusion through a constant thickness of active calcium oxide is suggested.

Phase inversion in the mixing of immiscible liquids

Abstract: Data are reported on phase inversion in concentrated oil-water mixtures dispersed in a fully-baffled stirred tank. The results indicate that water continuous dispersions in which the water concentration is as small as 40% by volume can be formed. For a vertically centered impeller the concentration of the organic liquid required for phase inversion varies inversely with the rate of energy input. The effect of impeller position is also discussed. Cette etude porte sur les proportions et le degre d'agitation requis pour occasionner le passage de l'huile de l'etat de phase dispersee a celui de milieu dispersant dans les emulsions d'eau et d'huile. Les resultats indiquent la possibilite de conserver le caractere continu de la phase aqueuse dans un melange contenant aussi peu que 40% d'eau en volume. Dans le cas d'un agitateur centre verticallement, la proportion d'huile requise pour l'inversion de phase est inversement proportionnelle a la puissance fournie. L'influence de la position de l'agitateur est aussi etudiee.

The pipeline flow of capsules: Part 2: Theoretical analysis of the concentric flow of cylindrical forms

Abstract: Predictions of capsule velocity and pressure gradient accompanying capsule flow are made for an idealised system in which a long cylindrical capsule moves concentrically with respect to the pipe. The capsule velocity always exceeds the average velocity, for example, by 22% for laminar conditions and 3% for turbulent conditions, when the ratio of the capsule diameter to the pipe diameter is 0.8. The pressure gradient accompanying capsule flow is related to the pressure gradient which would exist if the fluid alone flowed in the pipe at the same average velocity as the combined flows for different combinations of laminar and turbulent conditions. For each combination only a moderate increase in pressure gradient is predicted provided the diameter ratio does not exceed about 0.9. In the particular case of turbulent flow in the capsule-free system and laminar flow in the annulus between the capsule and the pipe a decrease in pressure gradient of as much as 20% is predicted. A regime of instability is predicted in which neither laminar nor turbulent flow is stable in the annulus. Des predictions quant a la vitesse de la capsule et au gradient de pression sont etablies pour un systeme ideal comportant une longue capsule cylindrique en mouvement concentrique dans le tuyau. La vitesse de la capsule excede toujours la vitesse moyenne du fluide. Pour une capsule ayant un diametre egal a 0.8 diametre du tuyau, cette vitesse est de 22% superieure en regime laminaire et 3% en regime turbulent. Il existe une relation entre le gradient de pression avec et sans capsule si le fluide seul s'ecoule a la měme vitesse que la vitesse moyenne avec capsule et ce pour diverses combinaisons de regimes laminaire et turbulent. En autant que le rapport des diametres capsule/tuyau ne depasse pas 0.9 il n'est predit qu'une faible augmentation des pertes de charge. Pour le cas particulier de regime turbulent dans un systeme sans capsule compare au regime devenant laminaire dans l'espace annulaire cree par la capsule dans le tuyau une diminution de 20% du gradient de pression est envisagee. Un regime instable peut avoir lieu dans l'espace annulaire par lequel l'ecoulement laminaire ou turbulent n'est pas permanent.

Resonant bubbles in a vertically vibrating liquid column

Abstract: This paper reports measurements and theory concerning stationary, resonant single bubbles which have been formed in a vertically vibrating liquid column at frequencies of 40–1050 c./s. With liquids of high viscosity (ca. 10 poise) the bubbles can be made large enough to occupy the entire cross-section of the 2 1/2 in. diameter column: intense agitation is produced in the liquid above the large bubble or slug. Theoretical equations are derived for the resonant frequency of the stationary bubbles: agreement with measured frequency is within 20% for bubbles which only partly fill the column cross-section and within 10% for bubbles occupying the entire cross-section. Viscous damping appears to be important in the latter case. Cet article decrit une etude theorique et experimentale du comportement de bulles gazeuses stationnaires dans une colonne de liquide vibrant a des frequences de 40 a 1050 cycles/seconde. Dans les liquides visqueux (c.10 poises), il est possible de former des bulles d'un diametre suffisant pour qu'elles occupent toute la section de la colonne de 2 1/2 po. de diametre. Dans ce cas, on observe une forte agitation du liquide situe au-dessus de la bulle. La frequence de resonance ainsi calculee concorde avec la frequence mesuree en-dedans de 10% dans le cas de bulles occupant toute la section de la colonne et en-dedans de 20% dans le cas de bulles plus petites. L'amortissement dǔ a la viscosite semble un facteur important dans le cas de grosses bulles.

The pipeline flow of capsules: Part 1: The concept of capsule pipelining

Abstract: Pipelining science and technology may be regarded as developing through several generations, the first two being fluid and slurry pipelining, respectively. Third generation pipelining in which it may be possible to extend the practice and economies of such transportation methods to an even wider spectrum of commodities may be defined as the flow of materials in capsule forms, as massive rigid or semi-rigid segments of the supporting fluid. The flow of such capsule forms is recognized as a flow configuration which is stable, being normally encountered in the flow of equal-density immiscible fluids over a wide range of conditions. Because the capsule forms occupy appreciably less than the total cross-sectional area of the pipe, they move at a velocity greater than the average over-all velocity. In addition, the pressure gradient of a stream in turbulent flow tends to be reduced, rather than increased, by the presence of capsule forms. La science et technique des transports par pipeline peut ětre consideree comme s'acheminant vers une troisieme generation (les deux premieres s'appliquant aux fluides et aux suspensions) dans laquelle il sera possible d'accroǐtre les avantages pratiques et economiques de ce mode de transport en confinant des materiaux dans des capsules ou sous forme de segments rigides ou semi-rigides du fluide continu. L'ecoulement sous forme capsulaire, normallement obtenu avec des fluides immiscibles de densite egale, donne une configuration stable de l'ecoulement. La vitesse d'ecoulement des capsules est plus grande que celle de la masse du fluide puisqu'elles occupent une section moindre que celle du tuyau. De plus, la perte de charge en regime turbulent tend a diminuer en presence des capsules.

Viscosity of suspensions of coal in mineral oil

Abstract: Viscosity data for slurries of five solid particle systems suspended in a mineral oil are presented for solid concentrations up to 50% by volume. At volume concentrations of less than 30% the results are well represented by the Einstein equation in its fluidity form, the constant varying with the system between 2.65 and 3.15, (as compared with 2.5 in the theoretical equation). At higher concentrations the slurries are non-Newtonian, and no satisfactory correlation is available in this region, very little complete data for the high concentration region have been published. Slurry viscosities are greater for smaller particles, and are greater for irregular particles than for spherical particles. Slurry viscosities in regions of high concentration can be considerably reduced by careful selection of particle size distribution. Pressure gradients measured in an experimental pipeline carrying a suspension of coal in oil in laminar flow could not have been predicted using the viscosities determined in the laboratory. La viscosite pour des suspensions de cinq types de particules dans une huile minerale et pour des concentrations jusqu'a 50% volume est donnee. Pour des concentrations inferieures a 30% volume l'equation d'Einstein est compatible, la constante de l'equation variant, selon le systeme, de 2.65 a 3.15 (constante de l'equation theorique = 2.5). A des concentrations superieures les suspensions sont non-newtonien et aueune correlation ne satisfait le systeme dans cette region; peu de donnees pour cette region a forte concentration n'existent dans la litterature. La viscosite des suspensions augmente pour des petites particules ou des particules irregulieres plutǒt que spheriques. La viscosite dans la region de forte concentration peut ětre diminuee de facon substantielle par le choix judicieux des dimensions des particules. Les pertes de charge en regime laminaire mesurees dans un oleoduc experimental transportant du charbon dans une huile n'ont pu ětre predites en utilisant la viscosite obtenue en laboratoire.

Sedimentation in inclined vessels

Abstract: The rate of sedimentation of precipitated calcium carbonate in water was measured as a function of the solid concentration and the shape and angle of inclination of the container It was found that an experimentally determined coefficient had to be included in the settling equation proposed by Nakamura to make it fit the data Le taux de sedimentation dans l'eau du carbonate de calcium precipite est mesure en fonction de la concentration de solide, de la forme et inclinaison du contenant Un coefficient empirique doit ětre inclus dans la relation de sedimentation, proposee par Nakamura, pour ětre en accord avec les resultats obtenus

A study of the condensation of binary vapors of miscible liquids: Part 2: Heat transfer co-efficients for filmwise and non-filmwise condensation

Abstract: Heat transfer coefficients for total condensation at 750 mm. Hg of saturated, binary vapors have been measured for the four systems n-pentane + n-hexane, methanol + methylene dichloride, n-pentane + methanol, and n-pentane + methylene dichloride. Condensation was entirely filmwise for the first two systems, but was non-filmwise (dropwise in the extreme) for the last two at low temperature differences for solutions dilute in n-pentane. In the non-filmwise cases the heat transfer coefficients are greater than expected for filmwise condensation, but the difference is not nearly as great as occurs for steam condensation. This indicates the existence of a resistance in the vapor film for mixtures, as postulated by Colburn and Drew in 1937. Dropwise condensation of vapor mixtures does not require a promoter, and indicates that interfacial tension forces may not always be neglected in considering the stability of homogeneous condensate films for mixtures. Les coefficients de transfert de chaleur pour la condensation des systemes binaires suivants: n-pentane et n-hexane, methanol et chloromethylene, n-pentane et methanol, n-pentane et chloromethylene a 750 mm Hg ont ete mesures. La condensation se fait sous forme de film pour les deux premiers systemes mais non dans les deux derniers pour des gradients de temperature faibles avec des solutions faibles en n-pentane. Dans les cas ou la condensation n'est pas sous forme de film les coefficients sont plus eleves bien que cette difference soit moindre que celle qui a lieu pour les divers cas de condensation de vapeur d'eau. Ceci est en accord avec l'enonce de Colburn et Drew (1937) quant a l'existence d'une resistance dans le film vapeur pour des melanges. La condensation de melanges sous forme de goutelettes ne requiert pas de promoteur et il semble que la tension interfaciale ne peut pas ětre toujours negligee en considerant la stabilite de films liquides homogenes lors de la condensation.

Heat transfer across a scraped surface

Abstract: Investigations using three experimental scraped surface falling film vertical heat exchanger tubes (6 in., 12 in. and 24 in. by 1 in. D.) have been made. Water and water-glycerol mixtures have been heated in the tubes by passing them down the heated inside surface which was continuously scraped by rotating blades. Flowrates between 306 lb/hr.ft. and 1070 lb/hr.ft. were used, the rate of rotation was varied from 370 to 1600 rpm whilst the number of blades on the shaft was varied between 1 and 4. As a result of these experiments the following equation accurate within ± 20% is proposed for correlating the heat transfer coefficient in the range of the variables studied: Visual observations of the flow of the liquid down the tube indicate that the liquid is held as a continuous fillet in front of each blade. This fact is used in the Appendix* for the alternative suggestion for the characteristic dimension in the correlation. Les recherches executees a l'aide de trois tubes echangeurs de chaleur (6 po, 12 po, et 24 po.-1 po. diam.) munis de racleurs rotatifs dans lesquels des films d'eau et de solutions aqueuses de glycerine ont ete chauffes, sont presentees. Le film a l'interieur des tubes est en ecoulement vertical descendant et est continuellement racle par des pales rotatives. La vitesse de rotation a ete variee de 370 a 1600 rpm pour des debits entre 306 lb/hr. x pi. et 1070 lb/hr. x pi., en utilisant de 1 a 4 pales sur le racleur. A l'aide des resultats obtenus on a determine la relation suivante qui est valide a ± 20% dans la region des variables etudiees: L'observation visuelle demontre qu'un filet liquide continu est maintenu en amont de chaque pale du racleur. Cette autre dimension caracteristique est proposee pour inclusion dans la relation ci-haut.

A study of the condensation of binary vapors of miscible liquids: Part I: The equilibrium relations

Abstract: Liquid-vapor equilibrium data at 750 mm. Hg are given for the four binary systems CH3OH + CH2Cl2, n-C5H12 + CH2Cl2, n-C5H12 + CH3OH and n-C5H12 + n-C6H14. The second and third of these systems have been shown previously to exhibit the phenomenon of non-filmwise condensation, and the equilibrium data are used in the following paper to calculate (condensing) film coefficients for the liquid and vapor films. The first three systems are azeotropic, and the compositions and boiling points (at 750 mm. Hg) of the minimum-boiling azeotropes are given. Densities have also been measured for the system n-C5H12 + CH3OH at 25°C. and refractive indices at 25°C. for the other three systems. The calculated volume of mixing for n-C5H12 + CH3OH is positive at all compositions. A geometrical interpretation of this is discussed in comparison with results previously obtained for solutions of alcohols and carbon tetrachloride. Les valeurs de l'equilibre liquide-vapeur pour quatre systemes binaires: CH3OH + CH2Cl2, n-C5H12 + CH2Cl2, n-C5H12 + CH3OH et n-C2H12 + n-C6H14, a 750 mm Hg sont presentees. Il a ete demontre anterieurement que la condensation des second et troisieme systemes se fait avec apparition de goutelettes et non de film, et les valeurs d'equilibre presentees serviront dans un autre article a calculer les coefficients de film lors de la condensation. Les trois premiers systemes presentent un azeotrope et les compositions et temperature d'ebullition a 750 mm Hg pour l'azeotrope sont donnees. La densite du systeme n-C5H12 + CH3OH a ete mesuree a 25°C. ainsi que l'indice de refraction a 25°C. pour les autres systemes. Le volume de melange calcule pour le systeme n-C5H12 + CH3OH est positif a toute composition. Une interpretation en est presentee en comparant avec les resultats deja obtenus pour des solutions d'alcool et de tetrachlorure de carbone.

Kinetics of the catalytic oxidation of benzene

Abstract: The kinetics of the vapor-phase oxidation of benzene over a sulphate-promoted vanadium oxide catalyst were studied in a differential flow-reactor. Rates of oxidation of benzene were measured at temperatures in the range 324° to 400°C., for benzene concentrations from 1 × 10−3 to 6 × 10−3 moles/l., by analysing the products: p-benzoquinone and maleic anhydride. Reaction-rate data were summarized by the following equation based upon a mechanism suggested by Hinshelwood: Catalyst deactivation was observed during the oxidation of benzene. Benzene, naphthalene, and toluene oxidations over a common vanadium oxide catalyst were compared. Deactivation was observed with benzene and toluene, but not with naphthalene. The rate equation provides a useful empirical description of oxidation rates of individual compounds. However, the deactivation behavior of the systems and the rates observed indicate that the mechanism used in its derivation is not pertinent. La cinetique de l'oxydation en phase gazeuse du benzene sur un catalyseur d'oxyde de vanadium active au sulphate a ete etudiee. Les taux d'oxydation du benzene ont ete mesures a des temperatures variant de 324 a 400°C. pour des concentrations en benzene de 1 × 10−3 a 6 × 10−3 moles/l. Ces taux sont determines par l'analyse des produits: p-benzoquinone et anhydride maleique. La relation suivante, basee sur un mecanisme suggere par Hinshelwood, resume les taux de reactions. La deactivation du catalyseur a ete observee durant l'oxydation du benzene. Les resultats de l'oxydation du benzene, naphthalene et toluene sur un catalyseur normal d'oxyde de vanadium sont presentes. La deactivation a ete observee avec le benzene et le toluene mais non avec le naphthalene. L'equation decrite donne une presentation empirique utile des taux d'oxydation des composes individuels. Cependant la deactivation des systemes et les taux observes indiquent que le mecanisme propose n'est pas adequat.

The air flow resistance of glass fibre filter paper

Abstract: The air flow resistance of filter papers containing fine glass fibres was measured in the region of streamline flow. Average fibre diameters ranged from 0.18 to 14.4 microns and paper porosities from 0.75 to about 0.94. At atmospheric pressure, the data were correlated by the equation which was derived from an expression for the drag force on an individual fibre perpendicular to the direction of flow. The resistance coefficient k varied with fibre diameter according to the empirical relationship and was about 30 for the largest fibre diameter and 1.6 for the smallest. Two alternative methods are proposed for adapting the equation to pressures below atmospheric. La perte de charge causee par l'ecoulement d'air en regime laminaire dans des papiers-filtres contenant de la fibre de verre d'un diametre variant de 0.18 a 14.4 microns a ete mesuree. La porosite du papier variait de 0.75 a environ 0.91. La relation suivante, determinee a l'aide de la relation de la resistance a l'ecoulement perpendiculaire a une fibre individuelle, est presentee pour les conditions de pression atmospherique: Le coefficient de resistance k varie en fonction du diametre de la fibre selon la relation empirique suivante et est de 30 pour les grosses fibres et de 1.6 pour les plus petites. Deux autres methodes sont proposees pour adapter l'equation aux pressions sous-atmospheriques.

Experimental investigation of natural convection heat transfer in confined space for non‐Newtonian fluid

Abstract: Experimental work was carried out for the study of convection heat transfer of fluid confined between two horizontal plates. The rheological properties of the fluid can be described by Ostwald - de Wael model. The results as expressed in terms of dimensionless groups were successfully correlated by the following expression: The Rayleigh and Prandtl numbers are defined in the generalized sense with the flow behavior index, N, being considered as a correcting factor for the deviation from Newtonian behavior. Un travail experimental a ete entrepris pour etudier la transmission de chaleur par convection dans un fluide contenu entre deux plaques horizontales. Les proprietes rheologiques du fluide sont assimilees au modele Ostwald-de Wael. Les resultats sont exprimes avec satisfaction par la relation suivante: Les nombres de Rayleigh et de Prandtl sont definis dans leur sens general et l'index de “comportement hydraulique”, N, est un facteur de correction tenant compte de l'ecoulement non-newtonien.

Simultaneous development of velocity and temperature profiles for laminar flow of a non-Newtonian fluid in the entrance region of flat ducts

Abstract: The momentum and energy integral method of von Karman and Pohlhausen is used to solve the entrance heat transfer problem for a non-Newtonian fluid in a flat duct. The initial temperature and velocity profiles are assumed to be flat. The fluid is assumed to obey the Ostwald-de Wael model and its physical properties are assumed to be constant. Dimensionless expressions for temperature and velocity profiles are obtained by numerical methods. The results of this investigation indicate that, similar to the case of Newtonian fluid, the parameters which influence entrance heat transfer are x/b ratio, Reynolds number and Prandtl number, provided these groups are properly defined. La methode tenant compte du momentum et de l'energie de von Karman et de Pohlhausen est utilisee pour resoudre le probleme de la transmission de chaleur a l'entree d'un conduit plat pour un fluide non-Newtonien. Les profils initiaux de temperature et vitesse sont supposes uniformes. Le fluide est conforme au modele Ostwald-de Wael et ses proprieties sont supposees constantes. Les expressions sans dimensions sont obtenues a l'aide d'analyses numeriques pour les profils de temperature et vitesse. Les resultats de cette recherche indiquent que, similarement au cas des fluides non-Newtoniens, les parametres influencant la transmission de chaleur a l'entree, sont x/b, Re et Pr en autant que ces groupes son definis adequatement.

Studies of the critical heat‐flux for some binary mixtures and their components

Abstract: A pool boiler and a forced convection loop used for studying critical heat fluxes in binary mixtures are described. The geometry of the test element is shown to be an important variable in pool boiling experiments, affecting both absolute flux values and the variation with composition. Data given for AC and DC power supplies show that the critical heat flux is relatively unaffected by the power supply source. Empirical equations of the form (Q/A) c = const. Va ΔTbsub are given for benzene, toluene and acetone, which correlate the forced convection subcooled data with average deviations of 3.1%, 5.0% and 5.1% respectively. Forced convection subcooled data are given for the systems benzene-toluene and acetone-toluene showing the effect of composition on critical heat flux. It is concluded that, at forced convection subcooled conditions in certain concentration ranges, binary mixtures may exhibit critical heat fluxes which are higher than for either of the pure components. In this respect loop experiments are analogous to pool boiling ones. However, extrapolation from pool boiling experiments to loop conditions does not appear to be feasible under the present test conditions. Le taux critique d'apport de chaleur a des solutions binaires fut etudie dans des conditions de liquide stationnaire et de convection forcee. Cette etude a demontre que la geometric de l'element chauffant est une variable importante dans le cas d'un liquide stationnaire, ayant une influence aussi bien sur le taux d'apport de chaleur que sur sa variation en fonction de la composition du liquide. Cependant, il semble que le taux critique d'apport de chaleur soit independant du fait que le chauffage s'effectue au moyen de courant electrique continu ou alternatif. Des equations empiriques du type (Q/A), = const. Va ΔTbsub peuvent ětre appliquees au cas de convection forcee, des deviations moyennes de 3.1%, 5.0% et 5.1% ayant ete observees pour le benzene, le toluene et l'acetone respectivement. On a demontre que la longueur de l'element chauffant est sans influence sur le taux critique d'apport de chaleur sous les conditions d'essai. On a aussi etudie l'influence de la composition du liquide par des essais avec les melanges benzene-toluene et acetone-toluene dans des conditions de convection forcee. On conclut que sous des conditions de convection forcee et dans certaines gammes de concentration, les melanges binaires exhibent quelquefois un taux critique d'apport de chaleur superieur a celui des constituants purs. Sous ce rapport, les essais en convection forcee sont en accord avec ceux affectues sur liquide stationnaire. Cependant, il ne semble pas possible d'utiliser les renseignements obtenus avec un liquide stationnaire pour le cas de convection forcee.

Optimization of multistage separation processes by dynamic programming

Abstract: This paper is concerned with the optimization of multistage separation processes using the method of dynamic programming. In particular, optimal (economic) design and operating conditions are determined for binary, multistage mass transfer processes and for solid separation equipment. In the solid separation model, multicomponent feeds are considered. Examples are given in each case to illustrate the computational aspects of dynamic programming. Cet article traite de l'optimisation, a l'aide de programmation dynamique, des procedes de separation multistages. En particulier, la conception economique et les conditions d'operation optima sont determinees pour les procedes de transfert de masse multistages et de separation de solide pour les systemes binaires. Des alimentations a plusieurs composants sont considerees pour la separation des solides. Des exemples sont donnees dans chaque cas pour illustrer l'aspect calcul de la programmation dynamique.

Settling velocities of coal particles

Abstract: Settling velocities of coal particles falling by gravity in a mineral oil have been measured for particle sizes ranging from 80 to 2,000 microns, at slurry porosities of between 0.6 and 1.0. Velocities for the latter figure correspond to the terminal velocities of single particles. The terminal velocities were found to be within 25% of the predicted values for spheres and could, for Reynolds numbers less than 0.2, be related to the particle size (d) by the equation V = Kd2,15. The settling velocities of the slurries, which were all in the laminar region, are shown to be related to the slurry porosity (e) by the theoretical equation of Maude and Whitmore, namely V = V, where Vo is the terminal velocity. Values of n between 6.5 and 7.5 were found. Les vitesses de sedimentation naturelle de particules de charbon, variant de 80 a 2000 microns, dans une huile minerale et a des porosites de la suspension variant de 0.6 a 1.0, ont ete mesurees. Les vitesses pour cette derniere valeur correspondent a la vitesse limite de particules en chute libre. Les vitesses limites de sedimentation sont en deca de 25% des valeurs calculees pour des sphees et, pour des nombres de Reynolds inferieurs a 0.2, peuvent ětre assimilees a la dimension des particules (d) selon la relation V = Kd2,15. Les vitesses de sedimentation des suspensions, toutes en regime laminaire, sont en relation avec la porosite de la suspension selon l'equation theorique de Maude et Whitmore, soit V = V0 V, ou Va, est vitesse limite. Les valeurs de n ont varie entre 6.5 et 7.5.

Exploratory studies on batch and continuous foam separation

Abstract: Foam fractionation has been employed for inorganic and organic chemical separations, for the treatment of radioactive wastes, and as a tertiary treatment method for secondary sewage effluents. Although the general effect of the basic variables of foam separation has been established, a quantitative approach to the process has not been made. In this study, a fundamental analysis of foam separation as a mass transfer operation is presented, utilizing both equilibrium and rate concepts of mass transfer. Foam separations have been carried out employing aqueous solutions of dodecyl sodium sulphate and alkyl benzene sulphonate at concentrations ranging from 0.005 to 0.14% weight. The range of surfactant concentrations which can be handled under a given set of operating conditions is established. In the batch experiments, volumes and concentrations of the foam and residual bulk phases are presented for nitrogen rates of 200 and 320 cc./min. Flow experiments were carried out using gas rates of 320, 440 and 580 cc./min. and liquid feed rates of about 70 and 100 cc./min. In general, the concentration of the drain stream was relatively insensitive to both gas and feed rates, but the total removal rate was found to be a strong function of gas rate. La fractionnation par mousse a ete utilisee pour la separation de produits chimiques, organiques et inorganiques, pour le traitement de dechets radioactifs et comme traitement subsequent au traitement secondaire des eaux-vannes. Bien que l'effet general des variables fondamentales a ete etabli, l'approche quantitative du procede n'a pas ete realisee. Dans cette etude, les concepts de transfer de masse, taux et equilibre, sont utilises pour presenter ce procede comme une operation de transfer de masse. La separation des mousses a ete entreprise en utilisant des solutions aqueuses de dodecylsulphate de sodium et d'alcoylbenzene-sulphonate pour des concentrations variant de 0.005 a 0.14%. La variation de concentrations d'agents tensio-actifs, pouvant ětre utilisee pour certaines conditions d'operation, est etablie. En procede discontinu, les volumes et concentrations de la mousse et de la phase residuelle sont presentes pour des debits d'azote de 200 et 300 cc./min. En procede continu les debits de gaz sont de 320, 440 et 580 cc./min. et les debits de liquides sont d'environ 70 et 100 cc./min. En general, la concentration du residu est peu affectee par les divers debits de gaz au liquide, mais le taux de production est fonction du debit de gaz.

Phase equilibria in the system sulphur dioxide‐water from 25–300°c

Abstract: The liquid-vapor phase relationships in the system sulphur dioxide-water have been investigated by the dew and bubble point method. Measurements were made in the pressure range 4 to 250 atm. and the temperature range 25 to 350°C. At the higher temperatures and pressures the mixture in the tube reacted to give sulphuric acid and sulphur and the data in this region are inaccurate. Below the consolute temperature of 127.5°C. two liquid phases can be formed and the system becomes invariant when a vapor phase is also present. At higher temperatures the phase diagrams are of simple shape, and above the critical point of sulphur dioxide the liquid-vapor inhomogeneous regions become progressively smaller, eventually disappearing at the critical point of water. Les relations entre les phases vapeur et liquide du systeme H2O-SO2 ont ete etudiees par les methodes de point de rosee et d'ebullition. Les mesures ont ete prises pour des pressions variant de 4 a 250 atm. et pour des temperatures variant de 25 a 350°C. Les composants du systeme ont reagi, aux valeurs elevees de pression et temperature, pour donner formation de soufre et acide sulfurique. Les donnees dans cette region sont donc imprecises. Aux temperatures inferieures a 127.5°C. (temperature critique de solubilite minimum) deux phases liquides peuvent ětre formees et le systeme devient invariable s'il y a presence de phase vapeur. A des temperatures plus elevees le diagramme des phases ne presente aucune difficulte. Au-dessus du point critique du SO2, la region heterogene de vapeur-liquide diminue et disparait eventuellement au point critique de l'eau.

Age distributions for flow systems

Abstract: A generalized treatment of age distributions in a flow system is proposed. In this work the inflowing stream is allowed to have an arbitrary but stationary age distribution before entering the system. The inventory material may also have an arbitrary age distribution initially. The flow rate of inflowing stream may be a variable with respect to time in certain special cases. Une etude generale du probleme de la repartition d'ǎge des particules d'un fluide en ecoulement est presentee. Pour les fins de cet expose, on assigne au fluide une distribution d'ǎge quelconque mais permanente (independante du temps) a l'entree du systeme. Le taux d'ecoulement peut ětre variable en fonction du temps dans certains cas particuliers.

The separation of H2 and D2 by moving‐bed adsorption: Corroboration of adsorber design equations

Abstract: Experimental concentration profiles obtained in the separation of H2 - D2 mixtures, by selective adsorption on charcoal in a moving-bed adsorber, were used to test the validity of semi-rigorous adsorber design equations based on considerations of gas film diffusion (utilizing the linear driving force concept), solid phase diffusion (utilizing Fick's law) and axial dispersion. The adsorption equilibrium data and solid phase diffusivities used in the design equations were also measured directly in separate experiments, whereas the gas film and axial diffusion values were evaluated from published data(3,0) In general, good agreement was obtained between the experimental and theoretically predicted concentration profiles, except at the lowest flow rates investigated. Les profils de concentration obtenus experimentalement dans la separation par adsorbtion selective sur un lit mobile de charbon, de melanges H2-D2, ont ete utilises pour verifier la validite d'une methode de calcul de colonnes d'adsorption. Cetto methode se fonde sur les concepts de diffusion du film gazeux (utilisant un gradient lineaire) de diffusion de la phase solide (utilisant la loi de Fick) et de dispersion axiale. Les donnees d'equilibre pour l'adsorption et les diffusivites de la phase solide utilisees dans les relations ont ete obtenues experimentalement alors que les valeurs de diffusion axiale et de diffusion du film gazeux ont ete evaluees selon la bibliographie. En general les profils de concentration experimentaux et theoriques sont en accord sauf pour les plus faibles debits utilises dans cette recherche.

The pipeline flow of coal‐in‐oil suspensions

Abstract: The flow behavior of coal-in-oil suspensions at velocities up to ca. 20 ft./sec. has been investigated in a one-inch d. experimental pipeline. Detailed data are presented for a bituminous and a subbituminous coal (effective size 70% w/w. At flow velocities greater than 2 ft./sec. and coal concentrations below 50% w/w, the suspensions were found to move as relatively homogeneous (or quasi-homogeneous) fluids, and pressure gradients followed the usual friction factor/Reynolds number relationship. But no satisfactory correlations could be established for flow at 50% w/w coal. In the latter case, laminar flow obtained at all velocities and the suspended particles tended to concentrate near the pipe axis (and to move along it as a definite ‘core'’. One effect of this phenomenon is a substantial reduction in the apparent viscosity of the suspension. Le comportement hydraulique de suspensions charbon-huile a ete etudie dans un oleoduc experimental (diametre 1′) pour des vitesses jusqu'a environ 20 pi./sec. Des donnees sont presentees pour un charbon bitumineux et un charbon sous-bitumineux (dimension effective inferieure a 700 microns) dans deux huiles de viscosite egale a 5.6 et 46.7 cp a 25°C. respectivement et ce pour des concentrations de charbon dans les suspensions allant jusqu'a plus de 70%. Les suspensions se deplacent comme des fluides relativement homogenes (ou quasi-homogenes) et les pertes de charge suivent la relation usuelle f/Re, pour des vitesses superieures a 2 pi/sec et des concentrations inferieures a 50%. Cependant aucune relation satisfaisante n'a pu ětre etablie pour des debits inferieurs a 2 pi/sec (influence appreciable due a la decantation) ou pour le comportement de suspensions superieures a 50% de charbon. Dans ce dernir cas, l'ecoulement laminaire a ete obtenu pour toute vitesse et les particules en suspension tendent a s'agglomerer pres de l'axe du tuyau et de s'ecouler comme un noyau bien defini. Une reduction substantielle de la viscosite apparente de la suspension decoule alors de ce phenomene.

Continuous thickening in an inclined thickener

Abstract: A continuous thickener inclined at 50° to the horizontal was compared with a conventional vertical thickener. When used to thicken a pulp of precipitated calcium carbonate in water the capacity of the inclined thickener was at least twice that of a similar vertical unit. A method for obtaining an approximate estimate of the capacity of the inclined thickener from batch settling data is suggested. L'operation d'un decanteur continu a parois inclinees, a 50° de l'horizontale, a ete comparee a celle d'un decanteur conventionnel a parois verticales. La capacite du premier a ete demontree comme etant plus du double de celle d'une unite similaire mais de type conventionnel, lors de l'epaississement d'une suspension aqueuse de carbonate de calcium precipite. Une methode pour l'estimation approximative de la capacite de cette unite est suggeree a partir de donnees de sedimentation en systeme discontinu.

The thermal and hydraulic characteristics of power reactor fuel bundle designs

Abstract: The type of fuel bundle evolved for the various Canadian heavy water moderated power reactors is described. The data necessary for estimating the thermal and hydraulic characteristics of this type of fuel bundle are indicated. The calculations and experimentation undertaken in the general fields of fluid flow, heat transfer and coolant mixing are then described in some detail. The future use of this type of fuel bundle with coolants proposed for more advanced reactor types is also discussed. La description de l'agencement du combustible developpe pour les divers reacteurs canadiens utilisant l'eau lourde est presentee. Les donnees requises pour l'evaluation des caracteristiques hydrauliques et thermiques de ce reseau de combustible sont indiquees. Les calculs et travaux experimentaux entrepris en hydrodynamique, transmission de chaleur et melanges refrigerants sont decrits avec details. L'utilisation future de cet agencement de combustible est discutee avec les agents refroidissants proposes pour des reacteurs de type avance.

Isobaric vapor-liquid equilibrium data for binary systems

Abstract: Vapor-liquid equilibrium data at atmospheric pressure are reported for the systems: 2-butanone-2-propanol, chloroform-2-propanol, ethyl acetate-2-butanone, and methyl acetate-2-propanol. The experimental results are correlated by two typical methods in the literature. Les valeurs de l'equilibre vapeur-liquide pour divers systemes binaires, a pression atmospherique, sont presentees soit: 2-butanone-2-propanol, chloroforme-2-propanol, acetate d'ethyle-2-butanone, et acetate de methyl-2-propanol. La correlation des resultats experimentaux est etablie a l'aide de deux methodes.

Coalescence of drops in liquid-liquid extraction columns

Abstract: Observations have been made of the presence of coalescence within an operating spray liquid-liquid extraction column, and of the ease or difficulty of coalescence at the column interface. On the basis of a mechanism proposed to explain coalescence and checked against the observations, qualitative predictions can be made as to ease of coalescence for ternary situations where a solute is transferred between two liquids, each saturated with the main component of the other. La presence ou absence de coalescence, ainsi que la difficulte de coalescence a l'interface, a ete observee dans une colonne d'extraction liquide-liquide a jet pulverise. Basee sur un mecanisme propose pour expliquer la coalescence et verifiee experimentalement, la possibilite de coalescence peut ětre predite qualitativement pour les systemes ternaires dans lesquels un solute est deplace entre deux phases liquides, chacune etant saturee avec le composant principal de l'autre.