bluuebunny/crossref_metadata_2025 huggingface dataset:
Annular flow of two immiscible liquids II. Analysis of core‐liquid ascent
Authors: Hasson D. , Nir A.
Published: March 2009

An analysis was made of the core‐liquid trajectory in the horizontal‐pipe flow of two annular immiscible liquids with a density difference. Evaluation of the vertical drag force resisting buoyancy was based on approximating the peripheral wall‐liquid drainage by local Couette flow integrated over the drainage passage. Inertia‐effect corrections to the Stokes solution were also taken into account from available information.

Experimental wall‐liquid thicknesses, measured from highspeed photographs, were in excellent agreement with predicted trajectories for the case of a non‐wavy interface, as assumed in the model. With a wavy interface, upper‐film thickness was considerably larger than predicted, suggesting that in spite of their disrupting tendency, the waves also contribute towards annular‐flow stability.
Excitation of spontaneous vibrations in enclosed diffusion flames
Authors: Deckker B. E. L. , Sampath P.
Published: March 2009

The presence of Tollmien‐Schlichting waves during the initial stages of the isothermal mixing of two axi‐symmetical laminar streams of air has been confirmed by comparing data from hot wire measurements with published two‐dimensional theoretical and experimental results for the stability of mixing and for transition in a boundary layer. Hot wire measurements in the flow field of steady or vibrating axi‐symmetrical laminar diffusion flames are remarkably similar to those obtained during isothermal mixing. A travelling wave in the mean flow direction has also been established. Data for these flames agree with the results of a higher order stability analysis for natural convection flow past a vertical heated plate. It has been concluded that Tollmien‐Schlichting waves are responsible for exciting flame vibrations.
End effects on interphase heat and mass transfer in a cubically packed bed of spheres
Authors: Clark Craw , Epstein Norman
Published: March 2009

Heat (and mass) transfer data were obtained for the constant rate evaporation of water from two layers of porous spheres in simple cubic array (ϵ = 0.4764) to a flowing air stream, over a particle Reynolds number range of 200‐900.

It was found that the cumulative effect of adding inert layers of non‐porous spheres at the entrance and exit was to lower (rather than raise, as in the case of randomly packed beds) the extent of heat and mass transfer between the active spheres and the fluid, the minimum number of inert layers required to eliminate end effects being three at the entrance and two at the exit. The specific effect of adding only one inert layer to the entrance, with none at the exit, was to raise somewhat the extent of heat and mass transfer. Interpretations are offered for these trends.

The simple cubic assemblage showed substantially lower values of the heat (and mass) transfer factors than those of randomly packed beds.
The production of synthetic crude oil from oil sand by application of the lurgi‐ruhrgas‐process
Authors: Rammler R. W.
Published: March 2009

Synthetic crude oil can be produced from oil sand by application of the Lurgi‐Ruhrgas process which is characterized by the circulation of fine‐grained heat carriers. The process is described and information given on its commercial application to date, which relates to the cracking of hydrocarbons to olefins and the carbonization of fine‐grained coal.

Reference is made to distillation tests on approx. 45 tons of raw oil sand. The yield of oil in commercial plants is expected to be approx. 95% by weight. Studies and computations show that beneficiated oil sand used as feedstock has advantages over raw oil sand.

It is suggested that in a commercial plant beneficiation and LR distillation should be combined. Based on the present state of Technology LR units for an output of about 8,000 ‐ 12,000 bbl/day of crude oil could be built. The approximate capital and operating costs of such a unit are indicated. In closing, reference is made to further possible applications of the LR process.
Wheat drying in well‐stirred‐batch and continuous‐moving‐bed dryers
Authors: Becker H. A. , Isaacson R. A.
Published: March 2009

Earlier studies established the physical chemistry and diffusion mathematics of wheat drying. This knowledge was applied in a mathematical model of continuous drying in a well‐stirred bed, and a good correlation of experimental results on spouted‐bed drying was obtained. Now a model has been formulated for both well‐stirred batch and continuous moving‐bed dryers of the commercial types. The set of mass and energy balances and rate equations has been solved numerically by digital computation. Heating and cooling cycles are both treated. Good agreement is found with the experimental data of Stansfield and Cook on a dryer simulating the performance of commercial moving‐bed dryers.
An analytical method applicable to the determination of individual concentrations of components, resulting from gamma induced iodination of methane
Authors: Vilenchich R. , Venter R.
Published: March 2009

A method combining the least squares approach with the Monte Carlo technique applicable to a set of m simultaneous linear equations in n unknowns has been developed to determine the n unknowns when the coefficients of the m equations are subject to a known distribution. The method is superior to the standard method when no Monte Carlo strategy is used, since the distribution of the n unknowns about a mean value is now also calculable, and a better comparison with experimental data is possible.

The method has been applied to the determination of the individual concentrations of components resulting from the gamma induced iodination of methane. The concentrations calculated by this method are compared to the actual measured concentrations used during experimentation.
Computation of chemical equilibrium compositions II
Authors: Storey S. H. , Van Zeggeren F.
Published: March 2009

A simple modification to a previously described search method for the computation of chemical equilibria is presented. The modification consists of an automatic correction for any drift which normally arises with the search method. The drift correction also obviates the need for starting estimates which obey atom balance conditions. The modified method is both faster and more convenient to use than the method described previously.
Mass transfer with chemical reaction inside single droplets and gas bubbles: Mathematical mechanisms
Authors: Wellek R. M. , Andoe W. V. , Brunson R. J.
Published: March 2009

The effect of a first order homogeneous chemical reaction on the rate of mass transfer inside liquid droplets and gas bubbles was determined. One of the models presented assumes the non‐oscillating dispersed phase is moving in the creeping flow region and the Hadamard stream functions are applicable. The results of the numerical solution of this model are presented graphically as a function of the Peclet number, reaction number, and dimensionless contact time. An oscillating droplet model is also presented which considers the effect of reaction within the dispersed phase.
H2S promoted oxidative dehydrogenation of butenes — A new dehydrogenation technique
Authors: Vadekar M. , Pasternak I. S.
Published: March 2009

A new technique, recently defined, uses an H2S/O2 mixture to selectively dehydrogenate hydrocarbons in high yields at temperatures of about 1100°F in the presence of suitable catalysts. In the new processing scheme, H2S is thought to react with oxygen to form reactive sulphur species capable of efficient hydrogen abstraction. The overall effect is thus the reaction between oxygen and hydrogen from the hydrocarbon to produce water and a more unsaturated hydrocarbon product.

The above technique is discussed in some detail for the oxidative dehydrogenation of butenes to butadiene. The importance of selecting the appropriate catalyst is emphasized and the various processing variables affecting the overall reaction are described.
The prediction of the PVT properties of sour gas mixtures
Authors: Swinton F. L.
Published: March 2009

Recent developments in the statistical mechanics of fluid mixtures due to Rowlinson and co‐workers have been applied to H2S/n‐alkane mixtures. The results have then been used to estimate the compressibility factor of a real sour gas mixture and the predicted theoretical value is found to be in excellent agreement with experiment.
Non‐steady, multi‐layered stratified flow
Authors: Pendergast D. , Cobble M. , Smith P.
Published: March 2009

A solution to the problem of non‐steady, stratified laminar flow of incompressible fluids through horizontal conduits is presented. The method is able to treat stratified flows of an arbitrary number of layers through two dimensional conduits and concentric flows of an arbitrary number of layers through cylindrical conduits by using the technique of quasi‐orthogonalization.

The validity of the method is tested by presenting results for a two‐layered start‐up flow in a two‐dimensional duct. As the time approaches infinity the velocity profiles calculated by this method agree with steady flow velocity profiles obtained by other authors.
On the measurement of liquid phase diffusivities for slightly soluble solids
Authors: Pradhan A. A. , Heideger W. J.
Published: March 2009

A procedure is developed to measure diffusion coefficients in the liquid phase for slightly soluble solids. Transient concentration profiles for the dissolution of a planar solid surface are obtained by means of a Mach‐Zehnder interferometer. Fitting of these profiles to Fick's second law then provides a measure of the diffusivity, even when it is concentration dependent.

Application of the technique to the water‐benzoic acid system yields a diffusion coefficient at 25°C which is 1.3 × 10−5 cm2/sec at infinite dilution and which decreases slowly as the concentration approaches saturation. The initial value for acetanilide in water is 1.1 × 10−5 cm2/sec at 25°C and again the diffusivity decreases as the concentration increases.
An investigation of the viscosity of dry air at elevated pressures and temperatures using a steady‐flow capillary viscosimeter
Authors: Goring G. E. , Eagan D. P.
Published: March 2009

A steady‐flow capillary viscosimeter, using dry air as the test gas, has been demonstrated at 150, 230, 330 and 430° Centigrade and over a pressure range of 35–150 atmospheres. Measured viscosities showed a maximum isothermal increase of about 4%. An extrapolation procedure was used to correct for flow and temperature discrepancies and a modified Hagen‐Poiiseuille equation, using variables evaluated at the mean capillary temperature, was applied to those data taken under nonisothermal conditions. The overall assembly and technique are capable of relative viscosity measurements having a standard deviation within 11/2% in the cited ranges.
Time dependent rheology of artificial slurries
Authors: Brown J. P. , Pinder K. L.
Published: March 2009

Gels, formed by suspending cellulose acetate particles of regular shape and size in a Newtonian medium, were sheared in a rotational viscometer to study their time dependent rheological behavior. Qualitative observations of the effect of the well defined particle parameters, shape surface area and concentration on the flow parameters were made.

The viscosity decay behavior fitted the model previously proposed by Pinder for slurries of natural particles.

By considering the effect of the weighting salt used in the suspending medium, it was found that the theory that ionic forces are active in stabilizing the thixotropic gel structure was supported.
Velocity and temperature profiles in compressible turbulent wall jets
Authors: Vlachopoulos John
Published: March 2009

The results of an experimental study on compressible turbulent wall jets resulting from a normally impinging round jet are presented. A finite difference technique was used for the calculation of velocity and temperature profiles. The eddy transfer coefficients used were functions of the distance from the plate throughout the flow field of the wall jet. The nozzle exit Mach number ranged up to 0.85. The nozzle exit temperature to the ambient temperature ratio ranged up to 2.92. The applicability of the calculational method has been thoroughly checked for a region of flow extending up to 12 nozzle diameters from the axis of symmetry. Using the empirical eddy transfer coefficients presented in this paper only starting profiles are needed to generate the solution for any point in the wall jet flow field which is described by a system of parabolic (boundary layer) equations.
Mass transfer with fast chemical reaction in drops
Authors: Tyroler G. , Hamielec A. E. , Johnson A. I. , Leclair B. P.
Published: March 2009

Mass transfer with a fast second‐order chemical reaction inside a drop has been studied photographically. Measured flow patterns and the reaction surface position have been compared with predictions of solutions of transport equations. The agreement is within experimental error.
Mass transfer into a horizontal layer of stagnant liquid under the action of instabilities+
Authors: Ruckenstein E.
Published: March 2009

The rate of absorption into a horizontal liquid layer undergoing an assumed steady cellular convection due to a concentration gradient or to the Marangoni effect is calculated. One concludes that a roll‐cell model can explain the large increase in the rate of absorption observed experimentally and that for large times a diffusional model, with a constant diffusion coefficient much larger than the molecular one, describes adequately the above situations.
On the measurement of zeolitic diffusion coefficients
Authors: Loughlin K. F. , Derrah R. I. , Ruthven D. M.
Published: March 2009

Crystal size distribution data and experimental sorption curves are presented for Linde 4A and 5A zeolites. It is shown that the deviation of the experimental sorption curves from the simple solution of the diffusion equation for spherical particles can be quantitatively accounted for by considering the shape and size distribution of the zeolite crystals. By working with well characterized samples of crystals it is thus possible to obtain reliable diffusivity data for rapid sorption processes by analysis of the sorption curves at intermediate and long times. The concentration dependence of diffusivity is briefly discussed.
Influence d'une agitation rotative sur le fonctionnement d'une colonne pulsée d'extraction
Authors: Subhasavasdikul S. , Alran C. , Boyadzhiev L. , Angelino H.
Published: March 2009

Les auteurs proposent l'utilisation d'un nouveau type d'extracteur dans lequel ils superposent deux agitations, l'une de pulsation, l'autre de rotation. Après avoir étudié les conditions hydrodynamiques de leur appareil, ils comparent ses performances à celles d'appareils plus classiques fonctionnant en continu à contre courant. A l'aide de deux mélanges ternaires, ils ont établi que l'efficacité de leur appareil est supérieure à celle d'une colonne pulsée ou d'une colonne à disques rotatifs: les hauteurs d'unités de transfert sont réduites par un facteur pouvant atteindre 2.
A principle of equivalent states for liquid transport properties
Authors: Cullinan Harry T.
Published: March 2009

A principle of equivalent states for liquid transport properties is developed for binary liquid systems. Under the assumption that the activity and viscosity corrected mutual diffusion coefficient is a function of the solution molar volume, working equations are developed for the concentration dependence of the binary mutual diffusion coefficients. The results apply to binary liquid systems for which the coefficient of thermal expansion is independent of composition and for which the difference in activation free energies for viscous flow and diffusion is also independent of composition. The results are tested with available data to show that the binary mutual diffusion coefficient can be predicted from the infinitely dilute values and the solution viscosity and thermodynamics for a large number of liquid systems.
Vapor‐liquid equilibria in the methane‐ethylene‐ethane system
Authors: Hsi Chu , Lu Benjamin C.‐Y.
Published: March 2009

Vapor‐liquid equilibrium compositions were measured for the methane‐ethylene binary at — 156.1°, — 173.1° and — 193.1° F, the methane‐ethane binary at — 173‐1° F, and the methane‐ethylene‐ethane ternary at — 173.1° F and at pressure up to 330 p.s.i.a. A forced recirculation apparatus was employed for the determinations. Liquid activity coefficients, γ, were evaluated by means of a modified Redlich‐Kwong equation of state incorporating with binary interaction constant and correlated by the Redlich‐Kister equation. Equilibrium data for the ethylene‐ethane binary system at — 173° F were predicted by the modified Redlich‐Kwong equation of state for correlating the γ values of the methane‐ethylene‐ethane ternary system.
Vapor‐liquid equilibria in the argon‐methane system
Authors: Gravelle Denis , Lu Benjamin C. ‐Y.
Published: March 2009

Vapor‐liquid equilibrium compositions have been measured for the argon‐methane system at 115.2°, 123.4° and 137.1°K, by means of a forced‐recirculation apparatus. A modified Redlich‐Kwong equation of state with the incorporation of a binary interaction constant has been successfully employed to represent the data. Liquid activity coefficients have been evaluated and correlated.
Dense phase vertical pneumatic conveying
Authors: Capes C. E.
Published: March 2009

Vertical pneumatic conveying was studied in a 3‐in. I.D. line, nineteen feet in length. Experiments were performed in both the empty line and in the line containing screen packing. Whereas in the conventional empty line choking occurs as the gas velocity is decreased, stable operation was possible in the screen packed line from the dilute conveying region down through the dense phase conveying region to the fluidizing region. A theoretical treatment proposed by Leung et al. to describe vertical transport of solids by liquids was used to predict the pressure drop/gas velocity relationship reasonably well for the screen packed line. Indications were obtained that the same equations may also be applied to conventional vertical pneumatic conveying in an empty line.
Two‐phase slug flow in horizontal and inclined tubes
Authors: Vermeulen L. R. , Ryan J. T.
Published: March 2009

Slug flow in the air‐water system near atmospheric pressure was studied in a one‐half inch diameter tube. Measurements of flow characteristics, pressure gradient, pressure fluctuations, slug velocity and frequency were made for horizontal and inclined flow.

A semi‐empirical theory based on a simple model was developed. Pressure losses calculated from this theory require a priori knowledge of the slugging frequency. A comparison of the prediction of the theory and two published correlations shows that the proposed theory gives better agreement with the data.
Friction factors for a tube rotating about its own axis
Authors: Harvey P. H. , Nandapurkar S. S. , Holland F. A.
Published: March 2009

Experiments have been carried out to determine pressure drops and flow patterns for fluids flowing through a tube rotating about its own axis. A newly developed pressure tap enabled the determination of pressure drops between two points in a rotating tube. The effect of rotation is to increase the friction factor in the laminar flow region and to decrease it in the turbulent flow region. Rotation also tends to suppress turbulence and to extend the laminar flow region to higher Reynolds numbers.
Experimental studies of interphase mass transfer with chemical reaction — Saponification of esters
Authors: Seto P. , Johnson A. I. , Hamielec A. E. , Furter W. F.
Published: March 2009

This study concerns the transfer of ethyl acetate from a supernatant still liquid into a lower layer of caustic solution in which a saponification reaction occurs. Apparatus and techniques for measuring the concentration profiles which develop in the turbulent reaction layer in the aqueous phase at the liquid‐liquid interface are described. In particular, the effects of turbulence on the reaction layer propagation, the reaction zone in the turbulent layer, and the concentration distribution of various components of the system were observed and measured. From these data, mass transfer rates and enhancement factors were deduced. The effects of turbulence in the aqueous phase were presented in terms of an eddy diffusivity model.
Laminar‐flow non‐newtonian heat transfer in flattened tubes
Authors: Oliver D. R. , Karim R. B.
Published: March 2009

It is shown experimentally that flattened tubes give higher laminar‐flow heat transfer coefficients than tubes of circular cross‐section. Part of the increase is due to an increase in the tube‐wall shear rate; the magnitude of this effect is predicted and checked by reference to the behaviour of Newtonian liquids. The other part is due to secondary flow patterns which develop in viscoelastic liquids; this effect is at a maximum when the aspect ratio of the tube cross‐section is of the order 1.5:1. The first effect may increase heat transfer coefficient by over 90% and the latter by over 45%.
H2S promoted oxidative dehydrogenation of ethane
Authors: Gaspar N. J. , Pasternak I. S.
Published: March 2009

In the H2S promoted oxidative dehydrogenation of ethane to ethylene, high once through conversions and selectivities (˜ 90%) have been achieved. This is due to the abstraction of hydrogen from ethane by active sulphur produced by the “in situ” reaction between H2S and O2 in the presence of a suitable catalyst. The extensive catalyst screening programme carried out to achieve the above results is described. The effect of processing conditions, e.g. temperature, space velocity and diluent type and amount, using one of the better catalysts found, i.e. cadmium on alundum is discussed.
Cyclic operation of a fixed bed ion exchange process: Experimental and computer simulation studies
Authors: Tan K. S. , Spinner I. H.
Published: March 2009

A quantitative study of cyclic fixed bed processes has been applied to binary and ternary ion exchange systems of general forms of isotherms. Mathematical models for simulating the cyclic operation are developed. Experimental results obtained from binary sodium‐calcium and ternary synthetic sea water systems are compared with the calculated results. In general, the agreement is very satisfactory. A significant aspect of this study is that all transport and equilibrium properties used in the column dynamics calculations are determined from independent estimates or measurements, without the use of column data. The good agreement between the experimental and calculated results indicates that a suitable mathematical model can be very useful for the engineering design and application of cyclic fixed bed processes.
Compressibility factor of sour natural gases
Authors: Wichert Edward , Aziz Khalid
Published: March 2009

This paper presents a comparison of twelve selected methods for the prediction of the compressibility factor of natural gases containing H2S and CO2. The methods are compared with experimental data from the published literature and with previously unpublished data made available by oil and gas companies operating in Alberta. The method of Robinson, Macrygeorgos and Govier, and the method of Robinson and Jacoby are found to be most accurate over the range tested here. A brief desription of the twelve methods considered is also presented.

Three new methods are also proposed. Two of the proposed methods are modifications of the Pitzer method and the Redlich‐Kwong equation of state. These methods are suitable for digital computer applications. The third method proposed here is developed for hand calculations. The new methods presented here are superior to the twelve methods tested in this study.
Optimal operation of a batch packed distillation column
Authors: Keith F. M. , Brunet J.
Published: March 2009

Optimal policies for a batch packed distillation unit are examined for the cases of variable reflux ratio and variable boilup rates. This work was to act as a follow‐up to Converse's work(1) for a batch plate distillation column with variable reflux policy. For the cases studied, it would seem that the boilup rate optimal policy yields better performance for the still than the reflux ratio optimal policy. The results of the present analysis and those of other authors seem to indicate that more effort should in the future be devoted to new modes of operation rather than to various refinements of the model used in the present and past studies. The present exploratory work seems to support the need for further studies using a packed rectifying section with variable boilup policy along with a novel mode of operation such as that considered by Mayur et al,(6).
A vertically oscillating sphere viscometer
Authors: Ray H. S. , Biswas A. K.
Published: March 2009

An apparatus, devised to measure the viscosities of relatively viscous liquids, is described. The device involves the motion of a sphere oscillated forcibly in the liquid with the help of an external driving mechanism. A theoretical analysis shows that the frequency and the amplitude of forced oscillation are independent of the density of the liquid and are solely determined by the viscosity for very viscons liquids. When the viscosity is sufficiently high, a completely developed laminar flow may be assumed at all stages of the motion. Under these conditions, the peak amplitude for resonance is suggested as a direct measure of viscosity.
Coalescence of an emulsion in a fibrous bed: Part I. Theory
Authors: Sherony D. F. , Kintner R. C.
Published: March 2009

A model of a fibrous bed coalescer is presented which relates the collision frequency between particles and fibers to the overall coalescence frequency. The model will predict the ratio of outlet to inlet particle number densities (Y) and takes into account the mean inlet particle size, mean fiber size, void fraction of the bed, superficial velocity through the bed, degree of bed saturation, and bed length. The ratio of outlet to inlet particle number density, in terms of these parameters, is given by

\documentclass{article}\pagestyle{empty}\begin{document} \[Y = \exp \left\{{- \frac{{3(1 - \in)S(1 + d_{10} /d_f)}} {{4d_f (1 - S)}}\eta _e L} \right\} \] \end{document}

where η is defined as the coalescence efficiency and varies between 0 and 1 with the fiber Reynolds number.
Coalescence of an emulsion in a fibrous bed: Part II. Experimental
Authors: Sherony D. F. , Kintner R. C.
Published: March 2009

A model of a fibrous bed relating the ratio of the outlet and inlet particle number densities to the various system parameters is tested experimentally. The degree of bed saturation is also determined from single phase and two phase flow data. The inlet and outlet particle number densities are determined by light scattering. It was found that the model does predict the effect of particle size, fiber size, bed length, and degree of saturation consistent with experimental observations. However, the coalescence efficiency based upon aerosol filtration theory is not amenable to the fibrous bed over the widest range of flow velocities.
General mathematical models of transport processes with and without chemical reactions
Authors: Chung Benjamin T. F. , Fan L. T. , Hwang C. L.
Published: March 2009

Based on the surface renewal and penetration concept, a number of fairly general mathematical models for transport systems without chemical reaction or heat generation and transport systems with zero and first order reactions have been developed. Solutions of the governing transport equations are presented for cases in which the number of capacitors of the multiple capacitance age distribution is finite or infinite. Some of their limiting solutions are reduced to those proposed by the previous investigators.
Residence time distributions in short tubular vessels
Authors: Veeraraghavan S. , Silveston P. L.
Published: March 2009

The results of an experimental study of the influence of vessel dimensions and fluid velocity on residence time distributions (RTD's) are presented. Length to diameter ratio (L/D) exerts the major influence on the RTD for the range of sizes and velocities studied. At L/D ≤ 2.6, the RTD resembles the response of a well stirred vessel with by‐passing to a pulse signal. Both Reynolds No. (NRe) and nozzle to vessel diameter ratio (d/D) effect the RTD. At L/D ≥ 5.2, the RTD resembles the response of stirred tanks in series to a pulse. NRe and d/D do not effect the RTD and can be neglected for scale‐up. The second and third moments of the RTD's and parameters of a finite stage model fitted to the RTD relate qualitatively to L/D, d/D and NRe, but neither the moments or the particular finite stage model used are satisfactory for quantitative correlations.
A correlation for predicting liquid viscosities of petroleum fractions
Authors: Abbott M. M. , Kaufmann T. G. , Domash L.
Published: March 2009

A correlation has been developed for estimating the liquid viscosities of petroleum fractions at 100°F and at 210°F. When used with the ASTM viscosity chart (or its analytical equivalent), the new correlation provides a method for the prediction of viscosity‐temperature behavior of fractions from the Watson characterization factor and specific gravity. Essentially an extension of an API Data Book viscosity nomograph, the proposed correlation substantially improves on the accuracy and increases the range of applicability of this method. Greatest accuracy is achieved for petroleum fractions in the kerosene to heavy gas oil range, although acceptable accuracy for most engineering calculations is also obtained for lube oils and for many complex pure heavy hydrocarbons.
Simulation of the transient behavior of complex chemical plants using a modular approach
Authors: Bobrow S. , Ponton J. W. , Johnson A. I.
Published: March 2009

A general computer program for modeling the dynamic behaviour of complex plants is described. Given the name DYNSYS, this program permits computation modules to be written for the various plant units, incorporating the differential equations describing their dynamic behaviour, then uses an Adams‐Moulton‐Shell integrating procedure. Process lags are also handled by the system.

Computation modules for control devices, such as a standard three mode controller, can be incorporated into the system. The program has been operated in both a batchwise and interactive mode using the CDC6400 computer.

The application of DYNSYS to the modeling of two chemical process units is discussed: a liquid‐liquid extraction unit for recovering butadiene in a synthetic rubber plant; and the modeling of a chlorine compressor system.
An optimal operating policy for a liquid‐liquid extraction column
Authors: Pang K. H. , Johnson A. I.
Published: March 2009

This paper is concerned with the policy to be followed when changing the product produced from a small liquid‐liquid extraction column from one desired composition to another. The grade control policy developed minimizes the production of off‐grade material, or allows the material produced during the change‐over period to have a desired average composition. Such policies are believed important in operating multiproduct plants in Canadian chemical industry, where product changes are frequent.

A linear dynamic mathematical model for the extraction column was derived from a previous frequency response study of a laboratory scale unit. The technique used in solving the optimal control problem is based on the minimum principle and a modified Riccati transformation.
The experimental determination of velocity profiles in smooth falling liquid films
Authors: Cook R. A. , Clark R. H.
Published: March 2009

A new photographic technique using tracer particles is described for measurement of the fluid velocity distribution in falling liquid films. The distribution for fully‐developed ripple free flow was measured with a precision of 1% for velocity and 4 microns for depth and was found to follow the theoretical Nusselt equation …

over the Reynolds number range 75–250 where the Reynolds number is defined as the ratio of the peripheral mass flow rate to the viscosity.

The technique is also applicable to flow close to any smooth reflecting planar boundary.
Gas holdup in a bubble column containing organic liquid mixtures
Authors: Bhaga D. , Pruden B. B. , Weber M. E.
Published: March 2009

Some anomolous observations of the gas holdup behaviour in binary organic liquid mixtures in a bubble column are reported in this note, to supplement the recently published data(1). The gas holdup was higher for mixtures of organic liquids than for either pure component. It is shown that none of the existing theories fully explains the data.
Dissolution of copper scrap in hydrochloric acid
Authors: Rigg Tyson , Marflitt William
Published: March 2009

The dissolution of copper scrap has been investigated as a possible approach to the production of copper chloride solutions for certain metallurgical purposes. The principal stages involved in the dissolution have been found to be (1) diffusion‐controlled attack of cupric ions on the surface of the copper, and (2) re‐oxidation of cuprous ions by oxygen. The effects of chloride concentration, acidity, temperature, agitation, metal surface area and oxygen partial pressure are described.
Convergence promotion in the simulation of chemical processes with recycle‐the dominant eigenvalue method
Authors: Orbach O. , Crowe C. M.
Published: March 2009

A new method, called the dominant eigenvalue method, is described for promoting the convergence of iterative computations of non‐linear problems, such as chemical processes with recycle. The method is based upon the observation that most iterations eventually approach a geometric progression. In the derivation it is assumed that the iteration can be approximated by a linear matrix difference equation,

The iteration continues until the largest eigenvalue of A dominates the solution. It may be used to extrapolate toward the solution before resuming the iteration.

The method is applied to the steady‐state simulation of two chemical processes, an alkylation plant and a distillation column. The computation time was reduced by up to a factor of four.
Stability of chemical reactors in the presence of sustained disturbances
Authors: Seborg Dale E.
Published: March 2009

A general method is developed for constructing regions of practical stability for nonlinear lumped‐parameter systems. The region of practical stability serves as a bound on the system response for a general class of magnitude‐constrained disturbances. The construction method is based on a modified Liapunov approach but is not restricted to a particular type of Liapunov function. The method is applicable to higher order systems in which several disturbance variables are present. Numerical results are presented for a CSTR with magnitude‐constrained disturbances in feed composition and feed temperature.
Thermophoretic acceleration of particle deposition from laminar air streams
Authors: Fulford G. D. , Moo‐Young M. , Babu M.
Published: March 2009

A preliminary study is reported of the use of temperature gradients to accelerate the deposition of small particles from laminar air streams. It is shown that appreciable effects can be obtained even with small temperature gradients and particles as large as 30 μm. An empirical correlation is proposed for the thermophoretic force based on the present results and those published previously for smaller particles.
Further studies on momentum dissipation of grid jets in a gas fluidized bed
Authors: Behie L. A. , Bergougnou M. A. , Baker C. G. J. , Base T. E.
Published: March 2009

Four experimental aspects of momentum dissipation of grid jets in a gas fluidized bed of cracking catalyst are reported. First, an investigation was made into the radial distribution of axial momentum for air jets issuing from vertical long nozzles into a minimally fluidized bed. The theory of Abramovich was compared with these experimental results. Second, data on the distribution of axial momentum along the axis for vertical air jets issuing from single and multi‐hole grids were compared with previous work. Third, the axial dissipation of vertical air jets loaded with fluid cracking catalyst issuing into air and also into a fluid bed was studied. Finally, the shape of the boundary of a jet dissipating into a fluid bed was compared to that given by theory.
Measurement of yield stress of fluid‐like viscoplastic substances
Authors: Vocadlo Jaroslav J. , Charles Michael E.
Published: March 2009

The concept of the yield stress of a fluid is discussed and the principle methods which have been used to evaluate it are critically reviewed. It is shown that many factors can influence the determination of this parameter. Most of the existing methods determine some property near an interface or wall rather than the actual yield stress value which is a physical property of the fluid itself. A procedure and technique for measuring the actual yield stress of a substance is suggested which seems to eliminate most of the shortcomings of other methods.
Withdrawal of cylinders from non‐newtonian fluids
Authors: Roy Subhash C.
Published: March 2009

The cylinder withdrawal theory for power‐law fluids proposed by Tallmadge has been compared with continuous withdrawal data in this work. Calculated withdrawal speeds differ greatly from measured values, although Tallmadge's gravity‐corrected theory for Newtonian fluids is in agreement with the present data on Newtonian fluids.

Correlations similar to that of Goucher and Ward have been developed with the experimental data over a 400‐fold range of dimensionless withdrawal speeds. These correlations are applicable for prediction of non‐Newtonian liquid film thicknesses on vertical wires and also apparently for viscoelastic fluids like CMC solutions, but are not applicable for inelastic fluids like Carbopol 934.
Mass transfer in liquid‐liquid (horizontal) pipeline contactors
Authors: Shah A. K. , Sharma M. M.
Published: March 2009

The mass transfer characteristics of liquid‐liquid (horizontal) pipeline contactors were studied for the bubble and plug flow regimes. The contactors were operated co‐currently. The theory of mass transfer with chemical reaction was used to obtain values of physical mass transfer coefficient (kLa) and effective interfacial area (a) for a number of systems. In all the experiments the resistance to mass transfer was confined to the continuous phase. The effect of the flow rates and viscosities of the two phases, interfacial tension, contactor length, pipe diameter, the presence of solids, etc. on both, kLa and a was studied. The values of kLa and a were found to vary from 1 to 50 × 10−3 sec−1, and 0.4 to 25 cm−1, respectively.
Removal of organic sulphur from coal gas
Authors: Bhatia S. P.
Published: March 2009

Organic sulphur compounds present in coal gas containing 15‐20% CO were effectively converted into H2S over a “Nimox” (nickel‐molybdenum) conversion catalyst. H2S was effectively removed by “Luxmasse”, a prepared iron oxide. The overall removal of organic sulphur depended upon the concentration of thiophene present. With only 10 ppm thiophene in the gas, the conversion of organic sulphur was 97% at 350°C after a single treatment. With six‐stage treatment at 350 psig, the final gas contained only 0.2 ppm total organic sulphur in the presence of 4‐5% water vapor.
Effect of temperature on the rates of dissolution of gibbsite and boehmite
Authors: Scotford R. F. , Glastonbury J. R.
Published: March 2009

The effect of temperature on the rate of dissolution of gibbsite and boehmite in caustic soda solutions was studied in the temperature range 25‐100°C. The results fitted the Arrhenius rate equation and the activation energy was found to be 30.6 ± 0.9 k. cal/g‐mole for the gibbsite reaction and 29.4 ± 1.3 k. cal/g‐mole for the boehmite reaction. While the effect of temperature on the boehmite dissolution has not been reported before, the value of the activation energy for gibbsite was higher than previously reported values. Reasons for these differences are given and a consistent value of the activation energy was obtained which agreed both with experimental data for different gibbsite samples and with modified forms of the previously published data.
General analytical solutions for first and second order, homogeneous, irreversible reactions, in ideal tubular reactors
Authors: Lo S. N. , Cholette A.
Published: March 2009

The two particular exponential integrals involved in the conventional solutions for ideal adiabatic tubular reactors are represented by a modified series for computation purposes. For arguments larger than ten in absolute value, the method of asymptotic expansion removes the inconveniences that may be encountered in the numerical evaluation of the solutions.

The expressions obtained with the modified series are not restricted by zero heat of reaction as is the case with the conventional solutions.

General solutions, easily amenable to computer evaluation, are presented for first and second order irreversible reactions, under adiabatic or isothermal conditions.
Precipitate flotation: A preliminary study of the underlying mechanism
Authors: Kalman K. S. , Ratcliff G. A.
Published: March 2009

Precipitate flotation has been investigated in a continuous steady‐state unit using magnesium hydroxide suspensions (con centration range 2‐28 × 10−4 g‐mole/l) and sodium dodecylbenzene sulphonate as surfactant (concentration range 1.5.10 × 10−5 g‐mole/l) at a pH of 11.75. Experimental results indicate essentially instantaneous equilibrium of the surfactant at the bubble‐liquid interface, and a substantial adsorption of surfactant on the metal hydroxide particles. The latter adsorption affects particle removal. Electron microscopy and photography have been employed to determine the sizes of the particles and bubbles respectively.

A model is proposed based on collisions between the particles and the bubbles. It allows for the coverage of surfactant on the particles and the available area for particles to adsorb on the bubbles. Tests of the model with data from continuous operation show an average deviation from experiment of under 10%.
Volumetric behavior of the ethane‐hydrogen sulphide system
Authors: Tiwari K. K. , Robinson D. B.
Published: March 2009

Experimental data are reported on the volumetric behavior of four mixtures of ethane and hydrogen sulphide containing 77.55, 63.52, 39.95, and 21.42% ethane in the temperature range from 50° to 125°C at pressures to about 5,000 psia. Compressibilities were fitted to the Benedict‐Webb‐Rubin equation of state for each mixture with an average deviation of 0.47%, although the variation of the coefficients with composition was not in accord with Benedict's mixing rules. Simultaneous evaluation of all coefficients other than γ using an equation of the form \documentclass{article}\pagestyle{empty}\begin{document}${\rm k}_{\rm m} = \sum\limits_{{\rm i} = 1}^{\rm N} {\sum\limits_{{\rm j} = 1}^{\rm N} {{\rm x}_{\rm i} \,\,{\rm x}_{\rm j} \,\,{\rm k}_{{\rm ij}} } } $\end{document} and the data from 639 experimental points gave an average deviation of 0.645% and a maximum of 5.61%.
A high pressure autocollimating refractometer for determining coexisting liquid and vapor phase densities
Authors: Besserer G. J. , Robinson D. B.
Published: March 2009

A high pressure apparatus has been developed for measuring refractive indices and compositions of coexisting phases in vaporliquid equilibrium. The refractive index is determined by measuring the angle of minimum deviation of a 30° prism with an autocollimating telescope mounted on a precision rotary table. The composition is determined by chromatographic analysis.

The refractive indices and compositions of the coexisting liquid and vapor phases in the carbon dioxide‐n‐butane system were obtained at 37.7°C and pressures up to 80 atm. The densities of the phases were calculated using the molar average refractivity and these compared favorably with previously published data obtained by direct volumetric measurements.
The silica gel‐water vapor sorption therm
Authors: Jury Stanley H. , Edwards Harold R.
Published: March 2009

The sorption isotherms for moist air and silica gel were determined at a total pressure of one atmosphere and 82, 100, 125, 150, 175 and 200°F. A small hysteresis effect was noted.

The silica gel‐moist air system can best be described by either of two equations. The first is the distribution function description of the Polanyi characteristic curve. If the data are described by this equation the adsorption process can be explained in terms of Polanyi's potential theory. Alternately, the data may be described by a double Langmuir expression.
A simplified form of Holland's equations in the solution of multicolumn distillation systems
Authors: Billingsley D. S.
Published: March 2009

When the Holland convergence acceleration scheme has been extended to multicolumn sustems as by Nartker, Srygley and Holland a second set of unknowns which they term “systemΘ's” is required. An alternate formulation is presented here in which the Holland equations for multicolumn systmes are expressed without the introduction of any unknowns beyond those previously used in formulating the Hollad equations for a single column. This formulation permits the existence and uniqueness of a positive solution to be established when and arbitrary number of units are arranged in a single recycle loop.

Furthermore a numerical difficulty encountered with the procedure of Nartker, et al is discussed and a modification is presented which elimiates the difficulty.
Optimal control of linear and nonlinear systems by two‐level optimization
Authors: Robertson Grant E. , Hawkins David J. , Luus Rein
Published: March 2009

The decomposition of a system into simpler subsystems, followed by the optimization of the individual subsystems, and then co‐ordinating the subsystem optimal solutions to yield the optimal control policy for the original system, is considered. Lasdon's co‐ordination algorithm, in which the subsystems are regarded as being completely independent, is improved by including the interdependence of the adjacent subsystems. For linear systems with a quadratic performance index, this procedure yields the optimal control policy in a single iteration from an arbitrary initial guess of the decomposition parameters. For nonlinear systems, the method includes linearizing the state equations, the calculation of the optimal control for the linearized system, and the adjustment of the corresponding decomposition parameters of the original problem until convergence is achieved. For the optimization of a nonlinear continuous stirred tank reactor such a procedure requires considerably more computation time than the standard techniques, and the optimum policies are less accurate.
Residence time distributions of a series of laminar stages
Authors: Maymo Jaime Antonio
Published: March 2009

The Residence Time Distribution (RTD) of a series of j cylindrical (and “slit”) geometry vessels with laminar flow is analyzed. Fully transverse mixing at the points of connection between cells and no significant contribution of molecular diffusion to the mixing process are assumed. This model leads to a one‐parameter (j) family of RTD curves, which are more asymmetric and long tailed than those predicted by the “ideal back‐mix cells in series” and “axial dispersed plug flow” models.