bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation of sparingly soluble salts: A model of agglomeration controlled growth
Authors: Baker C. G. J. , Bergougnou M. A. 
Published: March 2009

AbstractA model describing the role played by agglomeration in the growth of precipitates of sparingly soluble salts is presented. The model predicts that the mean size of the precipitate should increase with the agglomeration and unit particle generation rates, and that the resulting size distributions may be log normal. These findings qualitatively confirm previous experimental results. The model also shows that the precipitate size characteristics can be described in terms of a single parameter, a dimensionless drawdown time.
Vapor‐liquid equilibrium in the ethane‐carbon dioxide system
Authors: Hamam Salah E. M. , Lu Benjamin C. Y. 
Published: March 2009

AbstractVapor‐liquid equilibrium compositions were measured at four isothermal conditions from −60°F to 60°F over the pressure range from 101.5 to 827.0 psia for the binary system ethane‐carbon dioxide. A forced recirculation apparatus was employed for the determination.The data obtained were found to be thermodynamically consistent, and were compared favorably with the values predicted by means of a modified Redlich‐Kwong equation of state especially at the lower temperatures.
Sliding in inclined slurry pipelines at shutdown
Authors: Shook C. A. , Rollins J. , Vassie G. S. 
Published: March 2009

AbstractThe sliding phenomenon which is reported to impose a restriction upon the slope of slurry pipelines is investigated experimentally. Two different types of behavior which could be called “sliding” were observed.At pipe inclianations greater than 22° to the horizontal, fully settled layers of solid particles would slide with shear occurring at or near the pipe wall. The critical angle of inclination increased as the particle size decreased.When the slurry was not fully settled, a natural convective flow process was observed to move the slurry down a pipe incline. This flow occurred at much lower pipe inclinations. Concentration profiles measured near the bottom of a pipe incline showed little effect of slurry type or concentration, provided the slurry contained a significant amount of slowly settling solids. In this case, pipe slope was the most important variable.
Cyclic electrodialysis: Experimental results in a closed system
Authors: Thompson D. W. , Bass D. 
Published: March 2009

AbstractExperimental results are presented for cyclic reflux operation of an electrosorption — desorption separation process. Solute is alternately absorbed by, or desorbed from, a stack of multilayer ion‐selective membranes in a modified electrodialysis cell by periodically reversing the polarity of the applied electric field. Solution passes through a single set of flow channels parallel to the membrane sheets, and the flow alternates in direction synchronously with the electric current cycle. An axial concentration gradient is set up within the cell so that dialysate is produced at one end of the stack and concentrated solution at the other.Two cell designs are described, one containing a single stack of membranes, the other built in a modular arrangement with up to eight stacks in series. The effect of nine system parameters on the separation of aqueous NaCl solutions is reported for the first unit. Separation factors of up to 40 were obtained. For the second unit, the effect of channel length, displacement cycle, applied voltage and initial concentration on the rate of separation, the final separation factor, and the current consumption are reported. This unit has longer channels, more uniform flow distribution and less axial dispersion than the earlier design and gave separation factors > 103 with NaCl solution. Applications of the process to continuous separation in open systems are discussed.
Polymerization of butadiene with tii4‐Al(i‐Bu)3 catalyst: Part I: Kinetic study
Authors: Loo C. C. , Hsu C. C. 
Published: March 2009

AbstractA kinetic study on the polymerization of butadiene in toluene with TiI4‐Al(i‐Bu)3 catalyst has been carried out in a batch reactor. The effects of catalyst concentration, Al/Ti ratio, initial monomer concentration and temperature on the polymerization rate and the molecular weight distribution were investigated. It was found that the rate of propagation which is first order with respect to monomer concentration is a function of Al/Ti ratio, having a maximum rate at a ratio of 1.5 and decreasing rapidly as ratio increases. The number of active sites which is directly proportional to the concentration of Til4, is the prime determinant of the molecular weight of the polymer, yet the growth of the living polymer molecules is regulated by the chain transfer reaction to aluminum alkyls. The termination reaction was found significant only at Al/Ti ratio where the catalyst is most reactive.
A study of the effect of optimization function on calculated parameters of wilson equation
Authors: Brinkman Norman D. , Tao Luh C. , Weber James H. 
Published: March 2009

AbstractEstimated values of Wilson parameters depend upon the objective function which is used in the optimization procedure. The relationships between these estimated parameters seem to be more important than the values themselves, and the desirable paired parameters are confined to a region near ridge lines. This region represents a high level of joint confidence.In this study four different objective functions were used in the investigation of binary and ternary systems. Also, comparisons were made on calculated V/L equilibrium values predicted for ternary systems by using parameters estimated from binary and from the sole use of ternary data. Using the parameters estimated from binary data with a chosen objective function did not produce the best sum of squares of errors in a ternary system for the same objective function. Based on the overall performance, the best objective function to fit parameters in three ternaries is the one to fit the pressure.
Hydraulic characteristics of a valve in two‐phase flow
Authors: Tremblay P. E. , Andrews D. G. 
Published: March 2009

AbstractIn the case of boiling in nuclear reactor channels, it is apparent that the hydraulic characteristics of any valves used to control channel flowrates may have an important bearing on the critical channel power for the initiation of oscillations. The present investigation was therefore undertaken to determine the best model for two‐phase water‐steam pressure drop across such a valve. Pressures were between 300 and 1000 psig, mass fluxes between 0.1 and 0.5 × 106 lb m/hr‐ft2 and qualities up to 64%. The measurements were made in the FLARE rig of Atomic Energy of Canada Ltd. by one author during the course of a doctoral study on boiling instabilities. Various pressure‐drop models were tried. It was found that for turbulent flow a homogeneous model was the best.
The gaussian distribution of θ1/3 — a two‐parameter statistical model for approximating RTD's in CSTR's
Authors: Roy Paul‐H. , Choquette Pierre 
Published: March 2009

AbstractThe normal or Gaussian distribution of Θ1/3 is shown to give a satisfactory approximation of RTD's in continuous‐flow stirred tanks, whether mixing is ideal or not, and its mean Θm1/3 and standard deviation σ are, in each case, determined from the F‐curve as a function of Θ1/3 on linear probability paper.For ideal mixing, Θm1/3 and σ approach respectively the values of 0.89 and 0.32. In this case, the approximation is considered satisfactory for values of the relative time Θ ranging from 0.05, for F = 0.01, to 9.21, for F = 0.9999.As mixing conditions depart more and more for ideality, Θm1/3 assumes progressively lower values than 0.89 whilst the values of σ are all greater than 0.32. For a wide range of non‐ideal mixing conditions, the same approximation is satisfactory for values of Θ ranging from 0.125 to 5.0 and even up to 8.5 in some cases.
Théorie et application de la distribution normale de θ1/3 aux temps de séjour des fluides dans les réservoirs agités en régime continu
Authors: Roy Paul‐H. , Martinet J.‐P. 
Published: March 2009

AbstractLes modèles statistiques qui décrivent la distribution des temps de séjour dans une cascade de réservoirs de même volume et parfaitement agités se ramànent à une distribution normale de θ1/2, θ1/2, et θ selon que le nombre de réservoirs est respectivement > 15, > 50 ou trés grand.Pour un seul réservoir, la distribution normale de θ1/2 est une approximation satisfaisante de la distribution des temps de séjour pour l'agitation parfaite ou imparfaite. Pour l'agitation parfaite, la moyenne xm et l'écart type σ de la distribution de θ1/2 prennent des valeurs respectives de 8/9 et 1/3. Si l'agitation est imparfaite, xm et σ sont respectivement < 8/9 et > 1/3.Enfin, la distribution de θ1/3 permet la définition d'un critère simple de l'efficacité de l'agitation tout en étant conforme aux notions de Danckwerts.
Simulation of the oxidative dehydrogenation of methanol
Authors: Ulinder John D. , Tollefson Eric L. 
Published: March 2009

AbstractThe selective air oxidation of methanol over a 96.6% silver ‐3.4% copper catalyst supported on α‐alumina was studied to determine whether by supplying heat from an external source the extent of the dehydrogenation reaction to formaldehyde could be increased relative to the oxidative dehydrogenation route. Preheated reactants were fed over the catalyst which was held in place between glass wool plugs within a 0.16 inch I.D. quartz U‐tube. The latter was suspended in an electrically heated bath of fluidized alumina used to maintain constant temperature. Product analyses were made by gas chromatography using a Porapak N column. A mathematical model was designed to simulate the observed results. The results show that with the catalyst employed the addition of heat to supply the requirements of the dehydrogenation reaction and to decrease the extent of the oxidative reaction is not favorable in terms of formaldehyde production efficiency.
Some general considerations of reversible chemical reactions in batch and tubular reactors
Authors: Varma Arvind , Amundson Neal R. 
Published: March 2009

AbstractThe possibility of change in the algebraic sign of the net reaction rate of a single reversible reaction occurring in adiabatic or non‐adibatic batch and tubular reactors is investigated. This change is shown not to occur for adiabatic reactors; it may depending on the operating conditions and the system parameters for non‐adiabatic reactors. These and the related aspects of approach to system equilibrium are analyzed by an examination of the mathematical models describing these chemical reactors. Important results are summarized throughout the paper as Conclusions 1 ‐ 10. The results have direct applications in reactor design and operation. From a practical point of view it means that yield may be reduced in some cases by allowing too long a residence time even for a single reaction. Numerical examples are given to illustrate the results.
Kinetics of oxidation of pseudocumene in the vapor phase
Authors: Balasubramanian S. , Viswanath D. S. 
Published: March 2009

AbstractThe kinetics of pseudocumene oxidation in the vapor phase with tin vanadate as catalyst have been studied over the following ranges of the variables: Oxygen concentration, 0.909 to 2.857 mole/m3; pseudocumene concentration, 0.071 to 0.125 mole/m3; temperature, 260 to 320°C; space time, 22.5 to 90 × 104 g. catalyst/mole sec. Oxidation‐reduction models have been found to describe the kinetics adequately. The mechanism is found to remain the same throughout the temperature range covered.
Cracking of a dewaxed and extracted neutral distillate over La‐Y catalyst
Authors: Pachovsky Roman A. , Wojciechowski Bohdan W. 
Published: March 2009

AbstractA four parameter conversion model based on the time on stream theory of catalyst decay is applied to experimental data on the cracking of an extracted and dewaxed neutral distillate over La‐Y catalyst. It is found that in this system the decay exponent is very large indicating that m, the order of the decay reaction, is unity. Based on this finding, an exponential decay function has also been fitted to the data and it is found to give an equally satisfactory fit. It is also found that the value for the parameter W which describes the refractoriness of the feed is very high for this system, making the use of the refractoriness function unavoidable. The unusual behaviour observed here allows interesting comparison to be drawn between this system and that of Mid Continent Gas Oil over REHX catalyst. This in turn makes it clear that a) “standard” catalyst tests can be seriously misleading and b) that the behaviour of a feed‐catalyst system can not be properly described by any one simple concept such as “activity” or “refractoriness” but must take into account a number of parameters simultaneously.
Jet break‐up in liquid‐liquid systems
Authors: Skelland A. H. P. , Johnson K. R. 
Published: March 2009

AbstractA study was made of the jet length, jet contraction, and size of drops resulting from the formation and break‐up of liquid jets in another Newtonian, immiscible liquid. Drop size and jet contraction were correlated with system parameters, but attempts to correlate the jet length proved unsuccessful. Data were obtained from measurements of 4202 drops and 294 jet lengths and diameters on 294 photographs representing 92 runs. Variables included nozzle size, flow rate, and physical properties from six Newtonian liquid‐liquid systems.
Wettability control of glass beads
Authors: Singhal A. K. , Dranchuk P. M. 
Published: March 2009

AbstractWettability plays an important role in a number of industrial applications. Often it becomes desirable to control contact angles (wettability). For this purpose, two techniques for altering the contact angles of glass beads are described. These involve chemisorption of Silicones or Hexamethyldisilazane (HMDS) on glass surfaces.The results of measured contact angles on treated glass beads indicate that by carefully controlling the treating procedure, it is possible to obtain the desired wettability.
Dynamic behavior of reciprocating‐plate columns
Authors: Landau J. , Dim A. , Shemilt L. W. 
Published: March 2009

AbstractThe unsteady‐state behaviour of a reciprocating plate column in which adjacent plates move out of phase with each other has been studied experimentally by determining responses to step changes.The one‐dimensional, two‐parameter model developed, leading to a system of differential equations with time‐dependent coefficients, was simplified to allow parameter estimation in the Laplace domain. Special features of the experimental technique for obtaining instantaneous values of the tracer concentration which closely approximate to the average for a column cross section are described; the limitations of parameter estimation in the Laplace domain are discussed.
Heat transfer from a grid jet in a large fluidized bed
Authors: Behie L. A. , Bergougnou M. A. , Baker C. G. J. 
Published: March 2009

AbstractHeat transfer from a vertical grid jet within a 2 ft diameter and 4 ft deep fluidized bed of cracking catalyst was studied. The test nozzle diameter was varied from ¼ to 1 in. and the nozzle velocity from 50 to 250 ft /sec which is within the range of industrial practice. The axial temperature data have been related to a Froude, a Reynolds and a Nozzle number:In (δT/δTo) = –58.1 Fr−0.562 No1.08 Re−0.112A simple jet quenching model yielded heat transfer coefficients between the fluid bed and grid jet which ranged from 300 to 1200 Btu/ft2 hr.o F.
Hydrodynamic studies in natural and forced convection electrowinning cells
Authors: Gendron A. S. , Ettel V. A. 
Published: March 2009

AbstractHorizontal and vertical mapping of the cathode mass transfer coefficient was used to compare the hydrodynamics of full height model electrowinning cells employing either natural convection or two methods of forced convection. The most sgnificant improvement in performance was achieved with uniform agitation resulting from sparging gas over the cathode surface.
Sorption characteristics of binary hydrocarbon mixtures in low density polyethylene
Authors: Ghosh S. K. , Rawat B. S. , Krishna M. G. 
Published: March 2009

AbstractSorptions of six pure hydrocarbons and five of their binary mixtures in low density polyethylene have been measured. Composition of the binary mixture sorbed has been determined experimentally by a direct method. Selectivity due to sorption has been shown to constitute a major portion of the permselectivity.Correlations have been developed to predict the quantity and composition of the binary mixture sorbed in the polymer at any temperature, when the pure compound sorptions at some temperature are known.
SO2/O2 dehydrogenation of ethylbenzene
Authors: Gaspar N. J. , Cohen A. D. , Vadekar M. , Pasternak I. S. 
Published: March 2009

AbstractIn the SO2 dehydrogenation of ethylbenzene to styrene using alkalized alumina or titania catalysts, addition of small amounts of oxygen results in (1) higher styrene yields at equivalent SO2 concentrations, or (2) equivalent styrene yields with lower SO2 requirements. By staging the oxygen additions, styrene yields of greater than 80% are achieved at SO2 levels as low as 0.15 mole/mole ethylbenzene when 0.45 mole O2 is added in increments of 0.15 mole. The low SO2 concentration and staging of the oxygen result in a high selectivity (94%) for the reaction to styrene by minimizing both byproduct formation and combustion.
Experimental studies of single droplet liquid extraction with chemical reaction
Authors: Wellek R. M. , Rrunson R. J. 
Published: March 2009

AbstractExperimental data were obtained for the diffusion of a solute from the continuous phase into droplets falling in a single streani though a simple spray extractor. The solute reacted inside the dispersed phase by means of a second‐order reaction. The high droplet Reynolds numbers encountered necessitated the use of modifications of film and penetration approaches to arrive at methods for predicting single droplet extraction with reaction. The evaluation of the interfacial concentration was a special problem in this study.
A comparison of transient reactor models for non‐catalytic gas‐solid processing
Authors: Sampath B. S. , Ramachandran P. A. , Hughes R. 
Published: March 2009

AbstractTransient behaviour of packed bed reactors for non‐catalytic gas‐solid reactions has been simulated using the sharp interface, finite reaction zone and the particle‐pellet model for the reaction process occurring within the individual pellets. The solution procedures to the system of equations is based on the orthogonal collocation method. The effect of perturbations in the reactor inlet conditions on the temperature profiles encountered in the bed has also been examined.
Diffusivité de l'acide benzoi'que dans l'eau: Influence de la température
Authors: Lozar J. , Laguerie C. , Couderc J. P. 
Published: March 2009

AbstractBenzoic acid diffusivity in water has been determined using the diaphragm cell method, with a flexible and thin “Millipore” filter that leads to a reduction in the time of experiment. Twenty‐two experimental data points are given in the range 10–50°C. Two different correlations are proposed.
Removal of micron‐size particles from gases by turbulent deposition and diffusiophoresis
Authors: Azarniouch M. K. , Farkas E. J. , Cooke N. E. , Bobkowicz A. J. 
Published: March 2009

AbstractWhen one gaseous or vapour component diffuses across a space occupied by another component, there is a tendency to entrain and remove particles in the micron size range suspended in that space. This phenomena is called diffusiophoresis. The object of this work was to study the application of this phenomenon as a means of air pollution control when pollutant particles are suspended in a gas stream in turbulent flow. Under these conditions turbulent deposition also results in removal of particles from the gas stream. The test system chosen for study was sulfuric acid droplets suspended in air, with water vapour as the diffusing component. A concentration gradient was established by passing the mixture through a vertical tube whose walls were cooled. Experimental particle collection efficiencies agreed with efficiencies calculated from a theoretical model of the system. The energy requirement of this pollution control technique was analyzed.
The rate of mass transfer at a rotating cylindrical electrode with wiper blades
Authors: Nadebaum P. R. , Fahidy T. Z. 
Published: March 2009

AbstractA theoretical analysis of mass transfer at a rotating cylindrical electrode with wiper blades yields the dimensionless equation

where w is the number of the symmetrically located wiper blades, d is the wiper blade thickness and R1 is the radius of the wiped electrode. NuR, ReR and Sc are defined in terms of the cell and electrolyte parameters. Experimental evidence via the reduction of oxygen and ferrocyanide ions indicates that mass transfer rates can thus be predicted at no more than ±5% inaccuracy for Sc>200. The two‐wiper blade system is shown to effect an increase in mass transfer rates by a factor of 7‐8 with respect to a rotating cylindrical electrode without wiper blades.
Slurry and trickle‐bed reactor effectiveness
Authors: Sylvester N. D. , Kulkarni A. A. , Carberry J. J. 
Published: March 2009

AbstractOverall slurry and trickle‐bed reactor effectiveness with respect to mass transport limitation upon linear kinetics is readily assessed by utilization of estimated parameters and data secured in a single experiment. A judicious estimate of certain other physical parameters permits an estimate of the intrinsic chemical reaction rate coefficient. The procedure is illustrated with literature data.
A technique for analysing integral rate data in non‐ideal flow reactors to estimate unknown parameters
Authors: Cresswell D. L. , Quon D. 
Published: March 2009

AbstractA technique is described for analysing integral rate data taken from a non‐ideal flow chemical reactor characterised by the axial dispersion model, using a weighted residual approach.This approach avoids the formidable computational difficulties involved with the solution of the boundary value problem associated with the model differential equations. The measured concentration profile is approximated by a series of orthogonal polynomials. Model parameters are estimated by specifying that the fitting polynomial satisfy certain moment relations derived from the mass balance equation and boundary conditions.If the form of the rate equation is known, a priori, the estimation of the rate constant and the dispersion coefficient becomes explicit. In the more general case, in which the reaction order is also unknown, the estimation problem reduces to a uni‐dimensional search for the reaction order parameter (or the adsorption parameter in the case of complex kinetics). The method is applied to both linear and non‐linear systems and conclusions are drawn regarding the sensitivity of the chemical kinetic and transport parameters to experimental error.
Gas absorption in vertical slug flow
Authors: Golding J. A. , Mah C. C. 
Published: March 2009

AbstractAn investigation has been made of gas absorption characteristics in unstable vertical slug flow. The process studied was the absorption of hexane from an inert carrier gas into paraffin oil. Gas‐phase properties were varied by use of nitrogen, helium and Freon‐14 as carriers, while variation of liquid‐phase properties was achieved by using light and heavy paraffin oils and their mixtures. Absorption efficiencies were high, ranging from 0.75 to 0.99 The values depended not only on operating and system variables, but also on absorber geometry with a distinct discontinuity being observed when the overall mass transfer efficiency was plotted against absorber length H. This discontinuity was particularly marked for the heavy paraffin oil and was found to be related to the variation of slug surface area with H. Flow rates and system properties were found to affect the mass transfer coefficients and a comparison of experimental values with those predicted by the penetration theory suggested that not all the slug surface area was effective in mass transfer.