bluuebunny/crossref_metadata_2025 huggingface dataset:
Further studies on grid leakage in gas fluidized beds
Authors: Serviant G. A. , Bergougnou M. A. , Baker C. G. J.
Published: March 2009

Grid leakage data for single and multiorifice grids of various designs are given. The effect of the wind box volume on grid leakage has been investigated. A grid having long cylindrical nozzles can reduce solids leakage, but there is a critical nozzle length, for a given grid hole velocity, above which instabilities can occur. A method for computing this critical length is given. Implications for the design of commercial grids are discussed.
Bed expansion in a mobile‐bed contactor
Authors: Tichy J. , Douglas W. J. M.
Published: March 2009

The expanded bed height has been investigated in a 0.14‐m diameter mobile‐bed gas‐liquid contactor. The data obtained by two methods of measurement show that the bed height varies linearly with the gas flow rate and is independent of the packing density. The operation of the bed is characterized by the condition of flooding. Correlations are presented for the expanded bed height and the minimum fluidization velocity in terms of the independent system variables.
Average heat transfer coefficient during the direct evaporation of a liquid drop
Authors: Adams A. E. S. , Pinder K. L.
Published: March 2009

A dilatometric method was combined with a ciné photographic technique to obtain average heat transfer coefficients for the evaporation of droplets of isopentane and cyclopentane in a continuous phase of 0.0%, 56.02%, 73.07% and 77.06% glycerine‐water solutions. These average heat transfer coefficients and those calculated from the data of Prakash and Sideman were correlated by an equation combining the dispersed phase Nusselt number with the continuous phase Prandtl number, the liquid phase Bond number and a liquid viscosity ratio.

The dilatometric method of volume measurement was found to be better than the direct photographic method.
Mass transfer from a single moving spherical bubble in the presence of a complex chemical reaction
Authors: Shah Y. T.
Published: March 2009

This paper analyses the problem of mass transfer from a spherical bubble (Re << 1) in the presence of an (m, n)th order liquid phase reaction. The approximate analytical results for enhancement factor obtained, using a linearization technique of the rate expression which is an extension of the one proposed by Hikita and Asai, are found to agree well with the one obtained from a numerical solution of the problem.

The paper also presents numerical calculations of the rise in bubble interface temperature applying Danckwerts method to both the rigorous model as well as the extended penetration model of Ruckenstein et al. for the reaction process.
Effect of complete segregation on the performance of flow tank reactors
Authors: Lo S. N. , Cholette A.
Published: March 2009

An extension is presented to the theory of complete segregation proposed by Danckwerts for second order isothermal reactions in a CSTR. Introducing an integral average rate of reaction, it is now possible to compare the results directly and to show analytically that the conversion obtained under conditions of complete segregation is always larger than, or at least equal to, that for perfect micromixing.

The application of the concept of complete segregation of both heat and mass, as considered already by Douglas for adiabatic CSTRés, is extended further to show the influence of the kinetic parameters on reactor performance. Large variations are shown for the relative performance based on the two mixing extremes.
Sequential statistical design strategy in an experimental kinetic study
Authors: Juusola J. A. , Bacon D. W. , Downie J.
Published: March 2009

The value of using a sequential statistical design strategy is illustrated through its use in an experimental kinetic study of the oxidation of o‐xylene over a vanadium oxide catalyst. The rate of oxidation of o‐xylene was determined in a differential reactor over the following ranges of conditions: 270 to 300°C, (0.5 to 3.5) x 10‐4g.mole o‐xylene/1., (1.0 to 10.0) x 10‐3g.mole oxygen/1. The statistical design strategy for precise parameter estimation was found to be effective in increasing the precision of the parameter estimates, in reducing the correlation between parameter estimates and in showing the magnitude of this problem, and in providing a reliable prediction of the value of carrying out additional runs.
Drag force on isolated axisymmetric particles in stokes flow
Authors: Bowen B. D. , Masliyah J. H.
Published: March 2009

An approximate solution to the equation of motion governing Stokes flow past a number of isolated closed bodies of revolution is obtained by the least squares fitting of a truncated series expression for the stream function to known boundary conditions. The solution yields a reasonably accurate (±5%) estimate for the Stokes resistance on body shapes, such as cylinders and cones, for which analytic solutions are exceedingly difficult. The computed drag values were applied in determining the limitations of the various empirical expressions used to predict the drag resistance of these geometrically simple bodies. A new empirical correlation is presented.
Flow maldistribution in two dimensional packed beds: Part II: The behavior of non‐isothermal systems
Authors: Stanek V. , Szekely J.
Published: March 2009

A formulation is developed and computed results are presented for flow maldistribution in two‐dimensional packed beds involving non‐isothermal systems. Results are shown for both, systems in cylindrical and rectangular coordinates and the examples discussed include the pasage of a two‐dimensional temperature wave through a packed bed of non‐uniform porosity and the examination of the flow maldistribution that is caused by the radial non‐uniformity of temperature.

The results indicate that radial temperature profiles in packed beds may lead to flow maldistribution even under conditions where the porosity is uniform and it is suggested that this phenomenon may play an important role in the formation of hot spots.
Fonction de transfert d'un réservoir agité en système continu: II Variation des constantes de temps avec et sans différence de densité initiate
Authors: Pineault Gilles , Cloutier Leonce
Published: March 2009

The analysis of the dynamic behavior of a continuous stirred tank reactor with a fluorescent tracer has indicated that the short‐circuit of a fraction of the liquid feed constitutes the only non‐ideality in this case. There is no dead space or piston flow in the reactor when the density difference is zero.

The variation of the transfer function time constants was also studied as a first approximation, in a reactor with a density difference between the liquid feed and the reactor contents. This had led to the determination of an ideality criterion which includes the main causes of the non‐ideal mixing. The fluorescent tracer technique has permitted the isolation of the effects of physical parameters on the degree of short‐circuit from the effects on other causes of non‐ideal mixing.
Mass flux coupling by confined equilibrium reaction
Authors: Verhoff F. H. , Sundaresan K. R.
Published: March 2009

Various physical systems with either phase boundaries or semi‐permeable membranes can give rise to a confined chemical reaction. An analysis was performed to show the strong and potentially important effect of this confined reaction on chemical species diffusion through the region of reaction. The reaction was treated as one near equilibrium in order to obtain an analytical solution and to illustrate the strong coupling of fluxes caused by the reaction. Some generalities, e. g., facilitated diffusion of a single species transferring, were deduced using the above conditions and assumptions. These generalities are necessarily valid only for a single near equilibrium reaction with constant diffusivity of non‐diffusing species. Three examples were solved to illustrate the strong coupling of mass fluxes.
Continuous blending models for free radical polymerization systems
Authors: Kwon Young D. , Evans Lawrence B.
Published: March 2009

The dynamics of change of molecular weight distribution in free radical polymerization systems was modelled using a continuous blending concept which recognizes that the changes of molecular weight distribution are caused by continuous blending of increments of new polymer formed by the reaction into the already existing polymer, continuous blending of polymer at various parts of reactor by diffusion and convection, and continuous blending of polymer from various parts of reactor into the final product. The models have been applied to the analysis of both lumped and distributed‐parameter systems using either empirical or mechanistic relations for molecular weight of new polymer.
Enthalpies of n‐pentanol and n‐hexanol by flow calorimetry
Authors: Thinh T. P. , Ramalho R. S. , Kaliaguine S.
Published: March 2009

Enthalpies of two polar compounds: n‐pentanol and n‐hexanol have been measured by a flow calorimeter at temperatures between 300°F and 650°F and pressures up to 1,500 psia. The measurements covered the liquid, vapor, vapor‐liquid and critical regions. The experimental results were compared with values calculated by three methods for prediction of variation of enthalpy with pressure.
Convergence criteria for relaxation solutions of viscous flow around cylinders
Authors: Griffin F. O. , Meisen A.
Published: March 2009

Eighteen convergence criteria were studied for monitoring the relaxation solution of equations describing steady, Newtonian fluid flow perpendicular to circular cylinders. The criteria

which represent sums of fractional changes in stream function and vorticity over 100 iterations, are shown to be the most suitable.
Gas absorption with large heat effects in packed columns
Authors: Raal J. D. , Khurana M. K.
Published: March 2009

The system of design equations recently proposed by Treybal for adiabatic packed absorbers has been tested experimentally for ammonia absorption. Examination of temperature profiles and solute recoveries measured in a 6 in. packed column indicated effective interfacial areas for non‐isothermal absorption to be larger than those found by Shulman for isothermal absorption. A modification of Shulman's interfacial area relationship, giving good agreement between measured and predicted recoveries and temperature profiles, is proposed. A convenient algorithm for computer solution of the design equations is described.
On the dynamic modelling of porous catalyst particles
Authors: Elnashaie S. S. E. H. , Cresswell D. L.
Published: March 2009

A lumped dynamic model of à porous catalyst pellet is developed on the basis of the active site theory. This model is compared with a previous pseudo‐homogeneous model due to Liu and Amundson and found to differ in two important respects:

i) the effective mass capacity is much greater

ii) there is an additional heat generation term due to the adsorption‐desorption step.

Both differences are shown to have important conflicting effects on the stability and dynamic behavior of the pellet.
The velocity distribution within a hydrocyclone operating without an air core
Authors: Knowles Stephen R. , Woods Donald R. , Feuerstein Irwin A.
Published: March 2009

The three dimensional flow patterns in a 3‐in. diameter hydrocyclone operating without an air cone were studied using tracer particles and cine photography. Analysis of films at 55 locations inside the hydrocyclone yielded data for 18 velocity profiles at six vertical positions. These data were checked for consistency and compared with the results of earlier work in hydrocyclones operating with air cores. The tangential velocity profiles were found to be similar to those produced with an air core although, n. in VAIn = const, is about 0.2 to 0.4 instead of 0.7 to 0.8 for air core operation. In this work the radial velocity component was relatively independent of radius.
Rheological behavior of shear degradable oils: Kinetic and equilibrium properties
Authors: Petrellis N. C. , Flumerfelt R. W.
Published: March 2009

An investigation of the non‐Newtonian, time dependent, flow properties of various crude oils at or below their pour points is reported. Experimental observations of material response under various shear and stress conditions provide a basis for the development of a kinetic and rheological model which quantitatively describes the shear degradation and equilibrium behavior exhibited by these materials. Preliminary data on the effects of thermal history and aging are also reported, showing the relative importance of these factors to the rheological properties.
A mathematical model for cooperative diffusion
Authors: Balcezak W. K. , Stapper C. H. , Veno W. E. , Withers D. H.
Published: March 2009

This model is a mathematical description of the interactive, or cooperative diffusions of boron and phosphorus in silicon. The cooperative diffusions are explained in terms of enhanced diffusion coefficients which are concentration dependent. By using these coefficients, the coupled non‐linear diffusion equations are replaced by two non‐linear uncoupled diffusion equations. The model explains the so‐called emitter push effect found in phosphorus emitter/boron base devices. Results show excellent agreement with experimental profiles.
Comparative performance of packings for gas‐liquid contacting columns
Authors: Furter W. F. , Newstead W. T.
Published: March 2009

The performances of Raschig rings, Pall rings, Intalox saddles, and Berl saddles were compared in respect to pressure drop and mass transfer efficiency, in a 6‐in. I. D. tower having a packed height of 4‐ft., over a matrix of gas and liquid flowrates representing the irrigating and loading flow regimes. The mass transfer experiments were conducted employing a gas absorption system in which both phase films control the overall rate of mass transfer, an improvement in terms of industrial applicability over many previous studies.

The Berl saddles were observed to yield the lowest pressure drops of the four. The Intalox saddles yielded the highest overall mass transfer coefficients, followed closely by the Berl saddles and Raschig rings.
Ozonation of wastewater — some technical and economic aspects
Authors: Bowers A. , Netzer A. , Norman J. D.
Published: March 2009

This paper reviews traditional methods of ozone injection for wastewater treatment with special reference to the gas‐liquid contacting system. Operating characteristics and process efficiencies for the different systems described are compared. Recommendations are made about process selection for wastewater treatment by coronation.

The cost of ozone generation for wastewater treatment from air, used on a once‐through basis, is compared with recycled oxygen, with special reference to Canadian parameters. Capital investment costs for various plant capacities are presented and operating costs, as a function of oxygen lost during recycling, are calculated.
Regenerative sorption of nitric oxide: A concept for environmental control and kinetics for ferrous sorbents
Authors: Gidaspow Dimitri , Onischak Michael
Published: March 2009

A scheme for removing nitric oxide from flue gases and exhaust by regenerative sorption is proposed. Rates of sorption in the parts per million nitric oxide concentration range are presented for two ferrous sulphate‐silica gel sorbents. A kinetic model that correlates all observed room temperature data is derived.
Mass transfer effects in hydrogenations in slurry reactors
Authors: Ruether J. A. , Puri P. S.
Published: March 2009

The effects of external and internal particle mass transfer resistance on rate for hydrogenations carried out on finely divided catalyst in slurry reactors are treated. A method is developed for estimating external particle mass transfer resistance from rate measurements and is demonstrated experimentally. The existence of reactions with negligible internal diffusion resistance and significant external diffusion resistance is modeled theoretically and demonstrated experimentally.
Non‐Newtonian thin films: Theory and experiment
Authors: Sylvester Nicholas D. , Tyler James S. , Skelland A. H. P.
Published: March 2009

The flow of thin films of Newtonian and non‐Newtonian, Power law fluids down a vertical plate was studied in the laminar and wavy flow regimes.

A theoretical development based on the existence of a steady, periodic solution to the equations describing film flow was used to predict the flow characteristics of the film.

Double logarithmic plots of film thickness versus Reynolds number (ReP. L.) were linear, as predicted, up to a ReP. L. = 100. The ratio of surface to average velocity was found to be approximately independent of the Reynolds number at values predicted by a laminar velocity profile. The wavelength of stable waves was found to be independent of the Reynolds number for a given fluid.
On the efficiency of a venturi scrubber
Authors: Behie S. W. , Beeckmans J. M.
Published: March 2009

The performance of a venturi scrubber with a 1‐in. by 3‐in. throat was determined using monodispersed uranine‐methylene blue aerosols in the size range 0.8 to 3.0μm at throat velocities ranging from 109.6 ft/sec to 245 ft/sec. Separate measurements on the water separator showed that substantial aerosol removal took place in this unit, and the efficiency of the scrubber itself was calculated from these measurements plus overall efficiency measurements on the combination scrubber and separator. These results were compared with values obtained from a theoretical model and agreement was generally satisfactory, although the theoretical efficiencies were lower than the experimental efficiencies at the highest air velocities, and viceversa. This discrepancy may be due to a number of factors which are discussed.
The use of a radio frequency induction plasma for nickel extraction from serpentine minerals
Authors: Meubus Paul
Published: March 2009

The behavior of low nickel content (around 0.25%) serpentine, or (Mgx Fey Niz)3 Si2O5 (OH)4 has been studied in a radio frequency generated plasma. It has been found that a magnetic phase (spinel) enriched in Ni can be separated from the products of reaction. Nickel concentrations up to 2.3% were found in this phase which also should contain up to 50% of the total Ni present in the original serpentine. Average gas temperatures ranging from 3,800°K to 6,000°K were investigated while neutral (argon) and reducing (argon + hydrogen) atmospheres were studied. Mixtures of the mineral and carbon were also submitted to the high temperature reactions
The role of pore structure in the catalytic behavior of “unaged” and “aged” silica‐alumina catalysts
Authors: Ferraiolo G. , Peloso A. , Reverberi A. , Del Borghi M. , Beruto D.
Published: March 2009

This is a review of research concerning the role played by the porous structure of silica‐alumina catalysts on the evolution of organic catalytic processes. A strong effect of the geometrical shape of the pores on catalytic activity and selectivity has been evidenced.

The experimental results have also been interpreted by means of a simplified mathematical model, able to relate selectivity for a reaction of the type A → B → C to the geometrical features of macro‐microporous catalyst pellets, or granules.

The theoretical results are in qualitatively satisfactory agreement with the experimental data.
Optimal discrete stochastic control theory for process application
Authors: Macgregor John F.
Published: March 2009

The design of discrete feedback controllers which minimize some linear function of the variances of the output deviations from target subject to possible constraints on the variances of the inputs, for linear systems subject to stochastic disturbances, is treated from two points of view: (1) using transfer function models to characterizing the process dynamics and autoregres‐sive‐moving‐average models to characterize the stochastic disturbances, and then solving the optimal control problem using an approach due to Box and Jenkins and a discrete version of the Wiener‐Newton theory; and (2) using state variable models to characterize both the dynamic and stochastic parts of the system, and then solving the optimal control problem using the results of dynamic programming and Kalman filtering. Practical considerations such as model forms, their identification and estimation, and the development of variance relationships that are necessary for the application of these two approaches in the process industries are discussed. The relationship between and a comparison of these two approaches is made.
Heating and cooling of flocculated and non‐flocculated slurries in tubular heat exchangers
Authors: Crewe G. F. , Simons H. P.
Published: March 2009

The distinctly different turbulent heat transfer characteristics of flocculated kaolin slurries are compared with nonflocculated coal slurries via modified J‐factor correlation forms for tubular exchangers. Both slurry types were statistically best‐fitted with the approximate solution Bingham plastic flow model in preference to the local shear power law. In addition, the first known turbulent slurry heat transfer cooling results are presented along with the heating results. No distinction was made between heating and cooling correlation forms because of a random scatter of experimental points.

Experimental results were interpreted as follows

A. Flocculated kaolin slurries

JH = (h/CpG) (C/K1)2;3= 0.027(DVρ/μLeBϕ)0.2

11%ω < %ω Solids < 24%ω

Maximum Deviations: + 19.3%, − 17.8%

B. Non‐flocculated coal slurries

Jw = (h/CpG)(CpμLeBϕ/kw)2/3e−Bϕ/4)

=0.0285 (DVρ/ μLeBϕ)−0.2

13%w > %w Solids < 33.5%.

Maximum Deviations: + 17.8%, ‐ 11.1%
The distribution of solids between stages in baffled fluidized beds
Authors: Nguyen X. T. , Bergougnou M. A. , Baker C. G. J.
Published: March 2009

The partition of solids between stages in baffled fluidized beds has been studied. The bed, 9 ft tall and 11 in I. D., was divided into two or three stages by horizontal perforated plate baffles having open areas ranging from 11.5 to 34%. The spacing between baffles was varied from 1.5 to 3.5 ft. Four fluidized solids were studied and the velocity of the fluidizing air was varied between 0.2 and 2.5 ft/sec. A correlation was developed which enabled the solids holdup in each stage to be predicted.
Symposium on application of pulse techniques to kinetic measurements: Une nouvelle formulation dynamique des interactions fluide solide — Application à des mesures de diffusivités intraparticulaires et de constantes d'équilibre d'adsorption
Authors: Villermavx Et Jacques , Matras Didier
Published: March 2009

A general model of the dynamics of linear chromatographic interactions between a fluid and a solid is proposed, according to the following steps:

Analysis of the processes occurring at the particle level. Transfer function relating the mean concentration in the particle to the surface concentration. Contribution of external and internal mass transfer. Approximation by a first order system.

Transfer function of a mixing cell containing solid particles. Approximation by two coupled first order systems.

Generalization to any kind of flow. Association of mixing cells in series: model of a chromatographic column. Mean and variance of the impulse response.

Two experimental examples are given:

Measurement of the internal tortuosity and ethane adsorption isotherms in microporous alumina pellets using a spontaneously jet stirred gas solid reactor.

Determination of the effective diffusivity of argon in porous alumina beads using the so called “two measurements chromatographic method”.
Unsteady viscometric flow
Authors: Smith J. R. , Tory E. M.
Published: March 2009

Poncin's Navier‐Stokes solution for the falling head viscometer is obtained more directly by a Laplace transform method. Approximations which facilitate numerical evaluation are derived and Grumbach's result for an infinite capillary is obtained as a limiting case. A systematic series of approximations to the general, unsteady Euler duct equation are solved analytically. All solutions are compared with a numerical integration of the complete Euler duct equation. It is shown that all results become indistinguishable for sufficiently small Reynold's number and that the kinetic energy effect is clearly the major inertial effort.
The uniform film model for the gravitional approach of fluid drops to plane and deformable interfaces
Authors: Hartland S. , Robinson J. D.
Published: March 2009

Axisymmetric drainage within thin planar or spherical films of viscosity μ, area A and uniform thickness δ at time t is governed by the equation

where F is the force pressing on the film and n the number of immobile interfaces. Assuming that the film ruptures at a critical thickness which is independent of the physical properties and applied force, expressions of the form

may be obtained for drops approaching rigid and deformable interfaces and rigid spheres approaching deformable interfaces. The values of the exponents a, b and c suggest that an increase in drop volume, V, and density difference, δρ, and a decrease in interfacial tension, σ, should increase the coalescence time, τ, in liquid‐liquid systems. However in gas‐liquid systems an increase in δρ should decrease the coalescence time.

The variation of δ with time was obtained experimentally from capacitance measurements. For drops approaching a deformable interface, the corresponding values of n are always close to 1 and in the region between 0 and 2. The values increase when the interfaces are made less mobile by adding surface active agents; they are also larger for drops approaching a rigid interface and for rigid spheres approaching a deformable interface. Consequently the uniform film model adequately describes the approach of drops to rigid and deformable interfaces.
Transfert de chaleur par contact direct entre deux liquides immiscibles dans un mélangeur‐décanteur
Authors: Paquet M. , Grenier P.
Published: March 2009

It is shown by means of two performance criteria that a mixer‐settler combination can successfully be used as a direct contact heat transfer device between two immiscible liquids. This combination was operated under steady‐state conditions. The two criteria were a heat transfer efficiency and an overall volumetric heat transfer coefficient.

The experimental results show a considerable increase in efficiency and in the overall coefficient with increasing rotational speed of the agitator. These two criteria are also influenced by the ratio of heat flow rates of the two liquids; one particular value of this ratio results in a minimum heat transfer efficiency; at another value the volumetric coefficient passes through a maximum.
Heat and mass transfer from cylinders to a turbulent fluid stream — A critical review
Authors: Boulos Maher I. , Pei David C. T.
Published: March 2009

A review is made of recent experimental and theoretical work on the transfer of heat and mass between a circular cylinder and a turbulent fluid stream in cross flow. Special attention has been given to the transport mechanism over the wake region and the different approaches used to model it. The overall and boundary layer transport characteristics are briefly discussed. The review is limited to investigations under subcritical flow conditions over the Reynolds number range from 103 to 105.
The removal of copper, cadmium, and lead ions from dilute aqueous solutions using foam fractionation
Authors: Huang Robert C. H. , Talbot Frank D.
Published: March 2009

The removal of copper, lead and cadmium ions from aqueous solution by foam fractionation using sodium dodecylbenzene sulphonate (NaDBS) has been experimentally studied and theoretically predicted for solutions with a pH less than 4. A mathematical model of the system consisting of the equilibrium relations of chemical reactions occurring in the system was solved for the equilibrium concentration of all ions in the solution. Based on this equilibrium concentration and the effective radius of the hydrated ion, a modified theory of the Gouy‐Chapman diffuse double layer(9) was used to predict the distribution factor of the metal ions. The work was extended to systems containing two metal ions for the determination of the separability of the ions with respect to each other.

It was found that the distribution factor for solutions containing one metal ion could be predicted theoretically for a bulk solution pH less than four. Deviation of results above this pH was attributed to the limitations of the bulk solution reaction model because it did not include reactions for the formation of poly hydroxyl and poly nuclear hydroxyl complexes. Good agreement was also obtained between experiment and theory in the separability study. The results indicate that the order of removal of the ions from solution is Pb++ > Cd++ > Cu++. This sequence is the reverse order of the effective radii of the hydrated ions. The results support the fact that the mechanism for removal of the ions from solution is that of electrical attraction and that selectivity depends upon the charge and size of the hydrated ion.
Hydrogen reduction of the chlorides of cobalt and nickel
Authors: Rigg Tyson
Published: March 2009

Experimental results on the reduction of compacted pellets of the chlorides of cobalt and nickel are reported. The kinetics of the processes are considered in the light of the chloride vaporization mechanism previously proposed to account for the reduction of ferrous and chromous chlorides. Although all these reduction processes are superficially similar, substantial differences in reaction topography have been observed. These differences are attributed to the wide range of vapour pressure displayed by the various metal chlorides over the range of experimental conditions employed. Possible technical exploitation of these reactions is briefly discussed.
The pyrolysis of extracted solids from oxidized kraft black liquor after lignin precipitation
Authors: Bruley A. J. , Cook W. G. , Ross R. A.
Published: March 2009

A laboratory investigation of the possibilities for the reduction of odor from Kraft mill stack gases by lignin precipitation from oxidized Kraft black liquor and subsequent pyrolysis of the filtrate solids has been carried out. Samples of oxidized black liquor were acidified with sulphuric acid and the lignin precipitate extracted. The extraction scheme indicates that > 90% w/w of the sodium in the original black liquor samples can be retained in the filtrate after lignin removal at final pH 2.0. The evaporated filtrate solids containing the bulk of the black liquor inorganic chemicals were pyrolyzed and the evolved hydrogen sulphide, methyl mercaptan and dimethyl sulphide monitored by gas‐chromatography. Gas‐chromatograph traces displaying the increase and decrease of methyl mercaptant evolution levels on pyrolysis of the filtrate solids to increasing temperatures are shown.

A thermogravimetric technique was used to investigate the decomposition rates of the extracted samples and these rates correlated with the levels of sulphur gases evolved on pyrolysis. Heats of combustion were determined by bomb calorimetry. Sulphur losses from the filtrate solids and the Kraft black liquor total solids are compared. The results show a significant decrease in the evolution of organo sulphur gases from samples of ligninextracted black liquor solids in comparison with original total solids samples, an increase in the level of hydrogen sulphide evolution however, presents a problem.
Discrimination statistique des modèles: Application à l'étude de l'écoulement dans un réacteur dynamique à agitation
Authors: Tho Et Nguyen‐Xuan , Rouleau Denis
Published: March 2009

It often happens that those who carry out experiments must choose between two or more possible theoretical models; the use of the statistic discrimination enables them to make a judicious selection.

Several theoretical models have been proposed to represent the actual flow in a dynamic reactor involving stirring in a gas phase. Experiments have been carried out using propylene as a tracer and helium as a gas carrier, and involving feeding rates varying between 2 c. c./second and 33 c. c/second and rotation speeds comprised between 0 and 1000 rpm. The statistic discrimination of models enables to detect an inactive area in the reactor when the rates are lower than 11.8 c. c./second.
Bubble nucleation in saturated and subcooled boiling
Authors: De P. L. , Judd R. L.
Published: March 2009

An experimental investigation is reported for water boiling at atmospheric pressure on a copper surface in which the nucleation of bubbles was observed at an artificial nucleation site for five levels of heat flux between 11,700 Btu/hr ft3 and 19,600 Btu/hr ft2 and various levels of subcooling from 0°F to 32°F. Four mathematical models were evaluated. The experimental results were found to provide excellent agreement with the predictions of the Han and Griffith model for bubble nucleation.
Numerical studies of viscous stagnation point flows
Authors: Raal J. D. , Code R. K.
Published: March 2009

A rapid finite‐difference procedure for computing stagnation point flows at a given Reynolds number in terms of stream function and vorticity distributions is described. The method is illustrated for spherical and cylindrical curvature for Reynolds number ranges of 1 ≤ Re ≤ 400 and 4 ≤ Re ≤ 100 respectively. Predicted radial and angular velocity distributions in the frontal region are compared with results from numerical solutions of the full elliptic equations of motion. The use of a modified potential flow outer boundary condition reduces the region of numerical computation.
Continuous ion exchange in fluidized beds
Authors: Slater M. J.
Published: March 2009

A mathematical model has been developed for prediction of the performance of a continuous ion‐exchange column, comprising a series of fluidized beds of resin, operated with periodic flows of both phases. Simple small‐scale tests provide the data required in calculations. Experimental work was carried out on uranium extraction from unfiltered ore leach pulps and clarified liquors.
Spreading of crude oil on an ice surface
Authors: Chen E. C. , Overall J. C. K. , Phillips C. R.
Published: March 2009

The gravity‐viscous spreading of crude oil on artificially prepared ice surfaces was investigated. Five different types of crudes were studied with three surface roughnesses at ‐14°C. Crude oil No. 1 was also studied at ‐8 and ‐3°C. All spreading experiments were made with an oil volume of 45 and 20 ml. Regardless of temperature, surface roughness, oil type and oil volume, all data may be correlated by: where ρ, V and μ are the density, volume and viscosity of the oil, respectively, R is the radius of the oil slick, t is time, C is a constant and g is the acceleration of gravity.
A direct method for calculating ternary vapor compositions from total‐pressure measurements
Authors: Polak Jiri , Lu Benjamin C. ‐Y.
Published: March 2009

Ternary vapor compositions have been successfully calculated from total‐pressure measurements for four systems by means of a modified direct method, which involves the previously proposed concept of hypothetical binary mixtures, and permits the numerical integration using a simple P‐x relationship. The results of the systems tested further indicate that the ternary y values predicted from only binary P‐x data are not significantly different from the y values obtained when binary together with ternary P‐x values were used in the calculation, provided that the initial fit of binary P‐x data is successful.
Gas‐gas equilibrium: High pressure limits
Authors: Streett William B.
Published: March 2009

Recent experimental studies of phase behavior in mixtures of light gases, at pressures up to ten thousand atmospheres, provide information about high pressure boundaries to regions of gas‐gas equilibrium. It is shown that these regions are generally bounded on the high pressure side by a three‐phase region of the type solid‐gas‐gas, which results from the solidification of the less volatile component. In some cases the gas‐gas phase separation terminates at a critical end point formed by an intersection of the critical line with the three‐phase region. However, the available evidence suggests that in other cases gas‐gas phase separations may persist to very high temperatures at very high pressures, perhaps even to the limits at which atomic and molecular structure begin to break down.
An automated apparatus for precision density measurements of liquids
Authors: Adams W. A. , Yank R. , Christie R. O. , Kruus J.
Published: March 2009

An electronic controller is described which permits the automatic sequential mixing of two solutions. A small aliquot of each of the solutions produced is injected in turn into an electronic density meter displacing the previous solution and a digital recording is made of temperature and density. Results of a partial molal volume study of aqueous NaCl solutions at 25°C are presented (v_° = 16.621 cm3 mol‐1, S*v = 1.848 cm3 11/2 mol3/2, and bv = .0.138 cm3 1 mol12).
Gas flow patterns in spouted beds
Authors: Van Velzen D. , Flamm H. J. , Langenkamp H.
Published: March 2009

Profiles of local spout gas velocity, in both radial and vertical directions, were determined with a Prandtl tube, and of annulus gas velocities from static pressure measurements. It was deduced that the parameter governing the spout gas velocity is the momentum transfer rate at the gas inlet, and not particle characteristics. The results also showed evidence of downward gas flow in the annulus and thus recirculation of gas in the vicinity of the entrance nozzle, which is an hitherto unknown aspect of the spouted bed gas flow pattern.
Pressure drop and flowrate characteristics of a liquid phase spout‐fluid bed at the minimum spout‐fluid flowrate
Authors: Littman H. , Vukovic D. V. , Zdanski F. K. , Grbavčić Ž. B.
Published: March 2009

Data on the minimum spout‐fluid flowrates and the pressure drop in the annulus at that flowrate are presented as a function of bed height and nozzle diameter for a bed spout‐fluidized with water. The column was 62.6 mm. in diameter and contained 3.09 mm. glass particles. The particle Reynolds number at the minimum fluidizing velocity was 91.6.

A plot of the annular vs. the nozzle flowrate shows that the minimum spout‐fluid flowrates fall on a straight line between the minimum fluidizing and minimum spouting flowrates. The annular pressure drop is explained using an extension of the theory of Mamuro and Hattori.
Pressure drop, bed expansion and liquid holdup in a three phase spouted bed contactor
Authors: Vukov ÍC D. V. , Zdanski F. K. , Vunjak G. V. , Grbavčić Ž. B. , Littman H.
Published: March 2009

Data on the pressure drop, bed expansion and liquid holdup in a three phase spouted bed contactor with an initial bed height of 243 mm. were obtained as a function of the gas and liquid flowrate. Polyethylene spheres 10 mm. in diameter with a density of 320 kg/m3 were spouted in a 194 mm. column using a 30 mm. nozzle.

The spouted bed contactor with gas and liquid mass flow‐rates of 2.18 and 1.88 kg/m2 sec, respectively had similar pressure drop per unit area of particle surface, total liquid holdup per unit volume of operating bed, and “active” holdup, as a fluidized contactor.
The drying of barley malt in the spouted bed dryer
Authors: Brunello Giovanni , Peck Ralph E. , Nina Gilberto Della
Published: March 2009

The drying of barley malt was studied in a batch spouted‐bed dryer using three inlet air temperatures (60, 80 and 90°C) and three initial masses of malt (25, 30 and 35 kg).

One of the conclusions was that the drying can be conducted at higher temperatures than in the classical equipment.

A general correlation was obtained through the use of reduced moisture and reduced time.

A mathematical model which assumes only an external resistance of diffusion or heat transfer does not apply. Also, the model based on internal water diffusion does not predict the results. A new semi‐empirical model based on semi‐permeable membranes has been proposed.

A method of using batch laboratory drying data to predict the performance of continuous spouted‐bed driers has been outlined.
Eccentric laminar couette flow of long cylindrical capsules
Authors: Epstein Norman , Bianchi R. J. , Lee V. T. Y. , Bentwich Michael
Published: March 2009

The equation of motion for laminar Couette flow of an incompressible Newtonian fluid, induced by the eccentric longitudinal motion of a long circular cylinder in a circular pipe, is solved analytically. Expressions are obtained and typical plots presented for local velocity distribution, local shear stress distributions on both the surface of the pipe wall and the surface of the cylindrical core, total drag force on both pipe wall and moving core, twisting moment on the core, and volumetric flow rate of the liquid. As the eccentricity approaches unity, the solution for flow rate is shown to coincide exactly with a practical formula developed by Kruyer and Ellis to represent the Couette flow induced by the motion of cylindrical capsules.
Flow of a slurry through a venturi meter
Authors: Shook C. A. , Masliyah J. H.
Published: March 2009

Some of the factors governing discharge coefficients for slurries following through venturis are examined theoretically and experimentally. Coefficients greater than unity are predicted theoretically in the absence of wall friction effects. Experimental studies confirmed these values in an extreme case and indicated that like pipe flow, wall friction effects increase with particle density and diameter. The results suggest that the venturi meter should be more widely used for flowing slurries.
Oxygen transport in the intact red cell
Authors: Ho Shou‐Yien , Hershey Daniel
Published: March 2009

A rapid‐flow technique was used to study and determine the resistance of the red cell membrane to oxygen transport and the diffusion coefficient for oxygen transport in the red cell interior. With a mathematical description for the process in the intact red cell and experimental results, the magnitude of the membrane transfer coefficient (h) and the diffusion coefficient (D) can be obtained. Two models were considered. One is that of simple unidimensional diffusion through a red cell, shaped as a rectangular slab with no end effects (model 1) and the other is two‐dimensional diffusion through a cylindrical disc (model 2).

As a result of this study, it was found that, for model 1, the value of h, the oxygen transport coefficient for the membrane was 2.6 cm/sec, and D, the diffusion for oxygen transport inside the red cell, was 4.3 × 10−6 cm2/sec. For model 2, h and D were, respectively, 0.9 cm/sec and 3.8 × 10−6 cm2/sec.
Modelling of dispersion and dead space in an air chamber
Authors: Fan L. T. , Pereira N. C.
Published: March 2009

A combined model consisting of an active region and a stagnant region is used in representing the air flow characteristics in a continuous flow system. The active region is represented by the one dimensional axial dispersion model while the stagnant region is considered to be a dead volume having no fluid interchange with the active region. The mathematical model is fitted to experimental data obtained by subjecting the system to tracer step inputs. In the process of model fitting a dimensionless parameter of Pe. (Peclet number of the active region) is estimated. The effects of the internal geometry and structure of the flow system on the flow patterns are analyzed and substantiated by experimental data. Two possible mechanisms explaining the formation of stagnant regions have been proposed — that of reduced length, and that of reduced cross‐section. For the present investigation, the reduced length mechanism is found to explain the experimental data better.
Pyrolysis of municipal solid waste
Authors: Mcintyre A. D. , Papic M. M.
Published: March 2009

A state‐of‐the‐art review describing the characteristics of municipal solid waste (MSW) and assessing the chemistry and technology of pyrolysis of municipal solid waste is presented. The economics of the pyrolysis process are outlined.

Combustibles constitute on average about 60% of the weight of MSW and result in an average heating value (“as received” basis) of about 3,000 to 6,000 Btu/Ib. This makes MSW attractive for thermal treatment.

Municipal solid waste can be converted to gas, liquid and solid products by pyrolysis. Due to the complexity in composition of MSW the exact mechanism of pyrolysis is not known. Both homogeneous and heterogeneous reactions occur at the same time and both heat and mass transfer take place during the process. The relative yields of different products depends on the temperature of pyrolysis and the rate of heating. High pyrolysis temperatures and high heating rates favour the production of gases indicating high energies of activation for gasification reactions. At low temperatures, below 800°C, the pyrolysis process is reaction‐rate controlled, while at high temperatures, above 1,200°C, the process is diffusion‐rate controlled. Conditions of good heat and mass transfer are required for gasification of MSW. The residual char after pyrolysis can be gasified by further treatment with steam, hydrogen or carbon monoxide and water. The heat available from the products of pyrolysis is sufficient to sustain the process and yield some excess energy.

Three types of reactor design have been generally used in the investigation of pyrolysis of MSW; fixed bed reactor, fluidized bed reactor and rotary kiln reactor. The advantages and weak points of each of these are briefly discussed.

The costs of disposal of MSW by pyrolysis appear to be competitive with incineration.
Analysis of mednikov's equation for the transport of aerosol particles across a turbulent boundary layer
Authors: Beeckmans J. M.
Published: March 2009

Numerical solutions are presented for the problem of transport of aerosol particles across a turbulent boundary layer to an absorbing wall, using Mednikov's migration velocity mechanism in addition to molecular and turbulent diffusivity terms in the transport equation. It is shown that inclusion of the migration velocity term leads to a gross overestimate of the rate of transport at certain velocities, and it is concluded that Mednikov's expression cannot be valid in its present form.
The effect of isomerization on chemical equilibrium
Authors: Smith W. R. , Missen R. W.
Published: March 2009

A proof is given of the following statement: “If a set of isomeric forms is accessible to a chemical substance at equilibrium in a closed system (at given T and P, say) then the (relative) amount of the substance present at equilibrium is greater than it would be if only a strict subset of these forms were accessible”. The proof is restricted to ideal solutions. The statement is illustrated by calculations on the system consisting of benzene and the methyl benzenes to show the implications for equilibrium conversion and yield.
The use of statistical methods to build mathematical models of chemical reacting systems
Authors: Reilly Park M. , Blau G. E.
Published: March 2009

This paper describes a selection of the statistical methods which are available for designing and analyzing experiments for the purpose of choosing between rival mathematical models and for estimating their parameters. To exemplify how rival models might arise an approach to the writing of reaction rate expressions for chemical kinetic situations is given.