bluuebunny/crossref_metadata_2025_split huggingface dataset:
Continuous measurement of surface and interfacial tension by stationary slug method
Authors: Rao N. V. R. , Baird M. H. I. 
Published: March 2009

AbstractThe surface tensions of various liquids have been measured continuously by controlling their flow so that a slug of air is held stationary in a vertical tube. The dependence between the velocity (expressed as Froude number) and surface tension (expressed as Eotvos number) has been correlated for many low viscosity liquids. An extension of the correlation to viscous liquids has also been proposed and the effect of temperature has been studied.Due to dynamic surface tension effects, the data for surfactant solutions measured by this continuous method are higher than values found by static (equilibrium) techniques, so the method is not recommended for surfactant solutions.A slight modification of the apparatus and procedure permits the continuous measurement of interfacial tensions of liquid‐liquid systems, data for which are also presented.
Pressure drop, holdup and interfacial area in vertical two‐phase flow of multi‐jet ejector induced dispersions
Authors: Radhakrishnan V. R. , Mitra A. K. 
Published: March 2009

AbstractMeasurements are reported on pressure drop, holdup and interfacial area in a vertical column where a multi‐liquid jet ejector has been used for gas dispersion. Studies have been carried out in the bubble zone up to the onset of slugging. Correlations in terms of physical and dynamic variables have been developed to predict irreversible loss and holdup in such systems. Extensive statistical analysis showed that the correlations are highly significant at the 99 per cent confidence level. Measurements of interfacial area have been carried out by the chemical method. The measured values of the interfacial area were in the range of 5000 to 25000 m2/m3 in the ejector and 450 to 2650 m2/m3 in the total system. A correlation for predicting interfacial area has also been proposed as a function of the holdup in the system.
Wall‐to‐bed heat transfer coefficient in gas—liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A. 
Published: March 2009

AbstractWall to bed heat transfer has been studied in three‐phase fluidized beds with a cocurrent up‐flow of water and air. Six sizes of glass beads, two sizes of activated carbon beads and one size of alumina beads, varying in average diameter from 0.61 to 6.9 mm and in density from 1330 to 3550 kg/m3, were fluidized in a 95.6 mm diameter brass column heated by a steam jacket. Complementary heat transfer experiments have been performed also for a gas–liquid cocurrent column and liquid–solid fluidized beds.The wall‐to‐bed coefficient for heat transfer in the gas–liquid–solid fluidized bed is evaluated on the basis of the axial dispersion model concept. The ratio of the wall‐to‐bed heat transfer coefficient in the gas–liquid–solid fluidized bed to that in the liquid–solid fluidized bed operated at the same liquid flow rate is correlated in terms of the ratio of the velocity of gas to that of liquid and the properties of solid particles. A correlation equation for estimating the wall‐to‐bed heat transfer coefficient in the liquid–solid fluidized bed is also developed.
The effect of time on stream and feed composition on the selectivity of a cobalt fischer—Tropsch catalyst
Authors: Sarup B. , Wojciechowski B. W. 
Published: March 2009

AbstractThe Taylor–Wojciechowski formulation of Fischer Tropsch product distributions has been used to study the effect of time on stream and of feed composition on the parameters which arise in the T–W treatment. An experimental setup which allows the required evaluation of product yields is also described.The T–W formulation was found to give an excellent fit to data obtained using a cobalt‐on‐kieselguhr catalyst. Since the ratios of the various specific rates of parallel synthesis reactions were found to be different functions of the H2/CO ratio in the reactor, we conclude that propagation, branching and termination reactions are not governed by the same kinetics.
Peat adsorption of herbicide 2,4‐D from wastewaters
Authors: Cloutier Jean‐Noël , Leduy Anh , Ramalho Rubens S. 
Published: March 2009

AbstractThe possibility of utilizing peat as adsorbent for removal of the pesticide 2,4‐D from contaminated wastewaters has been evaluated in this investigation.Batch tests were conducted at different conditions of initial solute concentration, pH, particle size of adsorbent, temperature and ratios of weight of adsorbent to solution volume, in order to determine the optimum range of these variables for the adsorption operation. Removal ratios for the 2,4‐D of the order of 90% were obtained under optimum conditions. The adsorption of 2,4‐D in peat is described adequately by the Freundlich isotherm.Continuous tests, utilizing adsorption columns, were then conducted in order to determine the design parameters for a proposed treatment plant. The column tests were adequately correlated by the Bohart‐Adams equation.
Stabilisation of emulsion droplets by fine powders
Authors: Levine S. , Sanford E. 
Published: March 2009

AbstractFinely divided solids can stabilize emulsion droplets provided the solids are partially wetted by both the disperse liquid phase and the continuous liquid phase. The stabilisation of oil/water emulsions by finely divided solids in the presence of suitable organics has been related to the three phase (solid/oil/water) contact line. Schulman and Leja (1954a) and Taubman and Koretskii (1965) provide evidence that O/W emulsions are formed when the contact angle is less than 90° but inversion occurs to W/O emulsions when the contact angle exceeds 90°. We present a thermodynamic study of emulsion stabilization by finely divided solids, which is an extension of an earlier theory by Van der Minne (1928) who neglected interactions among the particles and droplets and also entropy effects due to Brownian motion. Only stable W/O emulsions are considered here. The starting point of the theory is an expression for the Helmholtz free energy associated with the oil/water interfaces stabilized by finely divided solids in the presence of surfactants. By minimising this free energy, it is shown that in a stable emulsion almost all the solid particles are adsorbed at the oil/water interface of the oil drops. This accounts for the experimental result that the average size of oil droplets decreases with increase in the concentration of solids. A particular example of emulsion stabilization by solids occurs in the hot water extraction process on the Athabasca oil sands. Both clay particles and anionic surfactants act as stabilizers of the bitumen droplets suspended in an aqueous alkaline environment.
Wood liquefaction with hydrogen or helium in the presence of iron additives
Authors: Bestue‐Labazuy C. , Soyer N. , Bruneau C. , Brault A. 
Published: March 2009

AbstractThe catalytic activity of several iron additives was studied during the liquefaction of poplar wood suspended in water at 340°C. Iron powder gave good oil yields of ∼40%. The iron seemed to be an effective additive at the beginning of the reaction before being converted into Fe3O4. A systematic study of the influence of the initial pressure and volumetric composition of the gas phase (hydrogen‐helium mixtures) was also made. An initial pressure in the range 4.0‐6.0 MPa was necessary, but the nature of the gas had no significant effect on the yield and the quality of the oils obtained when the percentage amount of iron on dry wood was at least 14%. A stoichiometric equation for the liquefaction reaction is proposed which agrees with experimental results regardless of the initial gas composition.
Flotation of Uranium from uranium ores in Canada: Part II — Cupferron adsorption on uranium oxide, quartz, illite and a uranium ore from elliot lake
Authors: Muthuswami S. V. , Vijayan S. , Woods D. R. 
Published: March 2009

AbstractMeasurements are reported for the equilibrium adsorption of cupferron from solutions by uranium oxide, quartz, illite, a mixture of these three, pitchblende, pyrite and brannerite ore. The cupferron concentration ranged from 1 to 6 g/L, and the pH was 7 and 8. Most isotherms followed the Langmuir model, although Freundlich behaviour was observed for illite and pitchblende. Most adsorption was pH independent except for illite and pitchblende. The adsorption isotherms for a mixture of uranium oxide, quartz and illite in the same proportions as in the naturally occurring ore agreed with the adsorption on the pyrite‐free ore at pH 8 but not pH 7. We attribute the discrepancy to the use of illite as the model clay.The specific adsorption of cupferron on quartz and illite is lower by a factor of about 50 and 5, respectively, than the adsorption on uranium oxide. Specific adsorption less than 1 mg cupferron per gm of pyrite free ore does not float the mineral. The corresponding equilibrium concentration of cupferron is 0.5 g/L. A qualitative model is given, and the implications of this work for practical operations are presented.
Photocatalytic oxidation of ethane over TiO2
Authors: Daroux M. , Klvana D. , Duran M. , Bideau M. 
Published: March 2009

AbstractThe photocatalytic oxidation of ethane has been studied at room temperature using a specially designed stirred reactor. The effect on the rate of ethane oxidation, of the partial pressure of reactants, the UV light intensity, the amount of catalyst and the residence time has been evaluated. Running the experiments according to a factorial plan permitted to deduce from a limited amount of experimental data the complete kinetic model corresponding to the steady state adsorption mechanism. On the basis of the experimental critical mass of the catalyst (1.5 g), an expression permitting calculation of the critical mass of the catalyst (TiO2) for any type of photocatalytic reactor has been derived.
Direct conversion of synthesis gas to aromatic hydrocarbons: Variation of product distribution with time‐on‐stream
Authors: Varma R. L. , Jothimurugesan K. , Bakhshi N. N. , Mathews J. F. , Ng S. H. 
Published: March 2009

AbstractThe synthesis of hydrocarbons from syngas was studied over a zirconia‐based cobalt‐nickel catalyst (FT catalyst) alone as well as mixed with zeolite HZSM‐5 at 101.3 kPa in a 12.7 mm i.d. down flow reactor. The product distribution was recorded as a function of time‐on‐stream for several days of continuous operation under fixed operating conditions of 250°C and H2/CO = 1. For the FT + HZSM‐5 system, a dramatic variation in the product distribution takes place during the first 24 h of operation. A comparison of time‐on‐stream results obtained using FT catalyst alone and mixed with HZSM‐5 suggests that the reactions leading to the build‐up of overall product distribution are slower over HZSM‐5 compared to those taking place over FT catalyst. These differences have been attributed to the different nature of reactions taking place over the two components of the mixed catalyst system. Analyses of the coke on the deactivated catalysts are also reported.
Improvement of separation efficiency in the continuous‐type horizontal thermal diffusion column with permeable barriers between the plates
Authors: Yeh Ho‐Ming , Tsai Shau‐Wei , Chen Wen‐Hon 
Published: March 2009

AbstractThe separation theory of the continuous‐type horizontal thermal diffusion column with permeable barriers has been developed by the orthogonal expansion method. Considerable improvement is obtained when the reflux rate and barrier positions are carefully chosen. The idea and mathematical formulism may also be extended to other conjugated Graetz problems with countercurrent flow and refluxes at the ends.
Cracking properties of some reforming catalysts
Authors: Al‐Madfai Suham , Abbas Abdullah A. , Ali Ahmed J. 
Published: March 2009

AbstractThe cracking properties of industrial reforming catalysts of γ‐alumina loaded with 0.6% Pt, with 0.35% Pt, and with 0.35% Pt plus promoters were investigated. The mode of cracking of these catalysts was studied after treatment under different oxidation and reducing atmospheres. Cumene cracking was used as a model reaction. The cracking products were collected and analysed, and the quantity of benzene produced was used to compare the activities of these catalysts. Maximum cracking was observed around 550°C for all catalysts studied. Cracking rates differed for various treatment conditions for the same catalyst, normally increasing after oxidation treatment. Marked changes in the cracking activity of unloaded γ‐alumina were observed after it was chlorinated. Benzene yield was studied in relation to possible complex formation of Pt‐Al2O3‐Cl2.
Retorting of oil shale from new brunswick, canada
Authors: Salib P. F. , Barua S. K. , Furimsky E. 
Published: March 2009

AbstractTwo oil shale samples from the Albert formation in the Moncton Sub‐basin, New Brunswick have been retorted in direct and indirect modes in a pilot scale moving bed retort. The maximum oil recoveries were 81% and 89% of the Fischer assay for direct and indirect mode retorting, respectively. Shale grade, bed height, retort temperature profile, recycle gas and its distribution, and air feed rate affected the oil recovery. The spent shale retained approximately 30% of the energy content of the fresh shale.
Fractionnement de deux bois tropicaux (eucalyptus et wapa) par traitement thermomécanique en phase aqueuse. Partie II: Caractéristiques chimiques des résidus et considérations cinétiques sur la solubilisation des hémicelluloses
Authors: Carrasco F. , Chornet E. , Overend R. P. , Heitz M. 
Published: March 2009

AbstractNous avons caractérisé par voie chimique les résidus solides issus de la liquéfaction par fractionnement en milieu aqueux de deux essences tropicales. Le procédé de fractionnement est constitué des étapes suivantes: préparation de la suspension aqueuse, préchauffage à 135°C, décharge à travers une restriction (ΔP = 17,2 MPa), réaction entre 180 et 230°C, puis refroidissement rapide.Les solides résiduels ont été analysés selon les deux méthodes suivantes:

hydrolyse acide: cette technique permet de quantifier les monosaccharides présents dans le résidu et de suivre ainsi la solubilisation des hémicelluloses et de la cellulose.
analyse élémentaire: cette technique s'est révélée ětre un indice de la solubilisation connexe des hémicelluloses et de la lignine.Par chromatographie gazeuse nous avons détecté le CO2 comme étant le seul gaz formé à des températures inférieures à 230°C.Deux modèles cinétiques de premier ordre relatifs à la solubilisation des hémicelluloses et à la formation du dioxyde de carbone ont été développés et appliqués aux résultats expérimentaux.
Statistical analysis of the removal of aluminum and magnesium impurities from wet‐process phosphoric acid
Authors: Feki M. , Chaabouni M. , Ayedi H. F. , Heughebaert J. C. , Vaillant M. 
Published: March 2009

AbstractThe present paper relates to the treatment of crude wet‐process phosphoric acid with ammonium nitrate and hydrofluoric acid to precipitate aluminum and magnesium impurities in the form of an easily separable phase: (NH4)xMgyAlz(F, OH)6.2 H2O. To check the effect of some concentration factors on this reaction, an orthogonal central composite design is realized with three variables: %Al3+, %NH4+and %F−. It is concluded that the amount of aluminum in acid is the limiting factor of magnesium precipitation. Thus complete removal of magnesium, which is a major impurity in wet‐process phosphoric acid, can be obtained by adding to the crude acid extra soluble aluminum salt simultaneously with hydrofluoric acid and ammonium nitrate.
The computer‐derivation of thermodynamic equationspart II. first and second derivatives for complex unrestricted systems
Authors: Farah N. , Missen R. W. 
Published: March 2009

AbstractAn algorithm, based on Jacobians and implemented on a microcomputer (IBM PC), is described for the derivation of expressions for first and second thermodynamic derivatives for complex systems, unrestricted, however, by (chemical) equilibrium constraints. The work has progressed through the design of two separate algorithms implemented by symbolic manipulation software. First, a thermodynamic derivation system, THERMODER1, was developed, aided by a symbolic mathematical system (muMATH‐83tm), together with its language of implementation (muSIMP), and certain user‐defined functions. THERMODER1 is capable of deriving expressions for first and second thermodynamic derivatives for simple systems (2 degrees of freedom, unrestricted). A second algorithm, THERMODER2, also implemented by the symbolic mathematical system, has been developed for both simple and complex (unrestricted) systems. THERMODER1 has been described previously, and THERMODER2 is described here. These algorithms are intended to be extended ultimately to chemical systems subject to equilibrium constraints. Examples, using THERMODER2, are given.
Effect of soluble ash components on the viscosity of lignite‐water mixtures
Authors: Sadler L. Y. , Bethany B. A. 
Published: March 2009

AbstractThe removal of multivalent cations from lignite‐water mixtures (LWM) was shown to lower mixture apparent viscosity by a factor of about 40, for example, at 100 s−1 by reducing both the yield stress and plastic viscosity. The cations Ca++, Mg++, Al+++, K+, and Na+, among others, were found to be present in the aqueous phase of the LWM in concentrations ranging from 546 ppm to 8 ppm. The primary anions present were CI− and SO4=. The degree to which the cations affected viscosity were of order trivalent > divalent > monovalent. The nature of the anion was found to be relatively unimportant. A process utilizing ion‐exchange resins for removing multivalent cations to produce low viscosity lignite‐water or coal‐water mixtures is described.
Spatial control of sheet and film forming processes
Authors: Bergh Luis G. , Macgregor John F. 
Published: March 2009

AbstractThe general problem of controlling both machine and cross‐directional properties on sheet and film forming processes is treated. A flexible class of linear dynamic‐stochastic models capable of characterizing the process and disturbance dynamics in these systems is suggested. Procedures are presented for identifying these models from data collected from common scanning type sensors. Linear‐Quadratic‐Gaussian (LQG) control theory is used to design multivariable controllers capable of jointly controlling the machine and cross‐directional property variations using both lumped and spatially distributed actuators.
Hydrogenation of cyclohexene and benzene over an amorphous pd‐zr alloy
Authors: Takahashi Takeshige , Nishi Yoshinori , Otsuji Nobuyuki , Kai Takami , Masumoto Takeshi , Kimura Hisamichi 
Published: March 2009

AbstractAmorphous Pd‐Zr alloys, produced by a rapid solidification technique, were studied to determine their catalytic activity for the hydrogenation of cyclohexene and benzene. The activity of the amorphous alloy without pretreatment by air was lower than that of the corresponding crystalline alloy, but it was gradually increased with the pretreatment. The surface area and the hydrogen adsorption activity of the alloys were simultaneously increased with the pretreatment. It is found from X‐ray diffraction pattern and SEM observation that palladium, which is an active species for hydrogenation in the amorphous alloys, is highly dispersed on the granulated ZrO2 surface by the pretreatment.
Drainage in thin planar non‐newtonian fluid films
Authors: Hartland Stanley , Jeelani A. K. 
Published: March 2009

AbstractEquations for the radial and linear drainage of non‐Newtonian fluids in horizontal and inclined films are presented. For a power law fluid with index m, the variation in dimensionless film thickness Δ with dimensionless time T is given by:

where Δ and T are appropriately defined for drainage in radial horizontal and linear inclined films. The corresponding approximate expression for a Bingham plastic fluid is:

in which A is the minimum film thickness defined appropriately at the asymptotic limits when Δ » A and Δ ⋍ A.
Investigations of fluid dynamics in mechanically stirred aerated slurry reactors
Authors: Wong C. W. , Wang J. P. , Huang S. T. 
Published: March 2009

AbstractThe fluid dynamics of stirred aerated slurry reactors with A‐310® propeller, 4‐blade 45° pitch turbine and 6‐blade Rushton disc turbine were studied over a wide range of gas flow rates. With respect to power consumption, gas hold‐up, and fluid dynamically limiting cases, viz., suspension and flooding, the Rushton disc turbine was found to be the best in stirred aerated slurry reactors. The influence of particle density, shape and mass fraction and of liquid properties on gassed critical stirrer speed, Njsg, and of gassed power input per unit volume, Pjsg, on particle suspension and gas dispersion, were investigated. Empircal correlations in combination with that of Zwietering were established for scale‐up design in three‐phase slurry reactors.
Ablation of ice‐solids and wax‐solids mixtures in turbulent axisymmetric water jets
Authors: Law Hin‐Sum , Masliyah Jacob H. , Nandakumar K. 
Published: March 2009

AbstractThe ablation rate of frozen mixtures of water or wax with finely divided solids subjected to a turbulent axisymmetric water jet was investigated both experimentally and theoretically. The range of the water jet Reynolds number was 8700–29300 and the jet temperature varied between 22 and 60°C. The solids used were very fine kaolinite clay, titanium oxide and aluminium powder.The type of solids and their concentration were found to affect the ablation rate of ice‐solids and wax‐solids mixtures. This is mainly due to changes in the physical properties of the melt layer of the water‐solids or wax‐solids mixtures which forms between the impinging jet and the frozen mixtures.
Remarks on random residence time distributions
Authors: Iordache Octavian , Corbu Sergiu 
Published: March 2009

AbstractA discrete stochastic mixing model for chemical reactor; is presented here. The turbulent flow system has been modeled as a network of ideally mixed compartments with interconnecting flows that are random variables.The model is particularly useful for studying the statistics of RTD and of the output concentration in a chemical reactor. Some computations of confidence intervals of concentration using information about the stochastic nature of flows are presented.
An application of MACSYMA in solving the laminar flow of micropolar fluid in a meandering channel
Authors: Easwaran C. , Majumdar S. R. 
Published: March 2009

AbstractPlane laminar micropolar fluid flow in a meandering channel of constant width is considered. A perturbation scheme based on the assumption of slow and slight curvature of the centreline is used to study the effect of curvature and various micropolar parameters on some flow properties. The symbol manipulation system MACSYMA is used to generate the successive perturbation equations. The effects of two different types of boundary conditions are investigated. The second approximation is given for a general centreline geometry. Results indicate that to the order of approximation considered, pressure gradient along the centreline is increased while shear stress on the walls is decreased for micropolar fluids and the effect of curvature becomes more pronounced with increasing micropolarity.