bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic and diluent effects on the emission of nitrogen oxides from hydrocarbon diffusion flames
Authors: Gollahalli Subramanyam R.
Published: March 2009

An experimental study of the quantities of oxides of nitrogen produced in hydrocarbon gas jet flames in concentric and cross‐flow air streams is presented. It is seen that the structure of flames has a strong influence on the quantities of NO and NO2 generated in diffusion flames. Increases in jet velocity result in the increase of NO and NO2 emitted from flames in concentric air streams. However, air stream velocity has opposite effects on the yields of NO and NO2 from flames in cross‐flows. Additions of diluent to jet and air streams decrease NO and NO2 in both concentric and cross‐flow air streams. The implications of scaling these results to fullsize flare stack flames have been discussed.
Gas liquid reactions in a packed bed: Some implications of the extended crossflow model
Authors: Patwardhan V. S.
Published: March 2009

The extended crossflow model was proposed earlier5 to account for the role of the stagnant zones of liquid in a packed trickle bed during absorption with a chemical reaction. Here the model is applied to a second order reaction to investigate the behaviour of the effectiveness f of the interfacial area of the static hold‐up during absorption with a chemical reaction. General criteria are developed which give conditions for the limiting behaviour of f for reaction kinetics of any form. Finally, a possible pitfall is described in detail which must be avoided in conducting kinetic experiments in a packed trickle bed.
Elimination d'anhydride sulfureux par réaction sur l'oxyde de cuivre en couche fluidisée
Authors: Barreteau D. , Angelino H.
Published: March 2009

Reaction between cupric oxide, oxygen, and sulphur dioxide has been studied in a fluidized bed reactor continuously fed with solid reactant. The effect of bed temperature, solid flow rate, gas flow rate and the hight at minimum fluidization conditions has been investigated.

Experimental conversions are between 20 to 60%.

Olcutt and Davidson's fluidized bed reactor model slightly modified for our particular reactor has been compared with experimental data. The assumption of plug flow of gas in the dense phase is good for the height of 5 cm, on the contrary, the assumption of perfect mixing of gas in the dense phase is better for the deepest bed.
The kinetics of the primary reactions in cumene cracking on lay catalysts of various mesh sizes
Authors: Best D. A. , Wojciechowski B. W.
Published: March 2009

A novel technique of obtaining fundamental kinetic data for complex chemical reactions on a decaying catalyst is described. The technique, based on the use of “Optimum Performance Envelopes” and initial selectivities, it used to determine the initial rate constants for the formation of all known primary prodiicts in the conversion of cnmene on Lay. From these data, the corresponding activation energies and frequency factors are estimated.

Using the above procedures to study the effects of diffusion on this reaction it has been shown that the effect of changing particle size is more complex than that predicted by existing theories of catalyst diffusion.
Effects of temperature and charge stock composition on the kinetics of catalyst decay
Authors: Pachovsky Roman A. , Wojciechowski Bohdan W.
Published: March 2009

A study of the kinetics of catalyst decay in the presence of a wax‐free and of a waxy feed has shown that the wax‐free feed causes decay by the poisoning of one site at a time whereas the waxy feed shows that wax poisons catalyst activity by competing one and two site mechanisms. In all these mechanism decay proceeds partly and perhaps totally by reactions involving two molecules of poison per deactivation event.
Reservoir depletion calculations for gas condensates using extended analyses in the peng‐robinson equation of state
Authors: Firoozabadi Abbas , Hekim Yusuf , Katz Donald L.
Published: March 2009

The Peng‐Robinson‐AGA computer program was applied to the predicting of liquid yields in flash and stepwise depletion calculations. Prior tests of the validity of the program were based on agreement between bubble and dew point pressures and equilibrium constants. Here, the liquid yields under ietrograde conditions were compared with only a moderate degree of agreement. The need for accurate extended analyses of condensate systems as well as the documentation of an accurate characterization of the cuts is emphasized.
Comparison of effective interfacial areas with the actual contact area for gas absorption in an agitated vessel
Authors: Kon Ngee Siew , Sandall Orville C.
Published: March 2009

Gas absorption with a pseudo‐first order chemical reaction was carried out in a turbine‐agitated vessel for the case of absorption across an unbroken interface. These experiments were carried out in order to determine the effective interfacial area for mass transfer. Carbon dioxide was absorbed in an aqueous carbonate‐bicarbonate buffer solution in the presence of an arsenite catalyst. The concentrations of arsenite used ranged from 0.05 to 0.2 mol/l. Effective interfacial areas determined from chemical reaction increased from 48.61 cm2 for an agitator speed of 100 r/min to 109.39 cm2 for an agitator speed of 750 r/min. The actual interfacial area was 179.50 cm2.
Quadratic model of the behaviour of a fluidized bed reactor: Catalytic oxidation of benzene to maleic anhydride
Authors: Kizer O. , Chavarie C. , Cassimatis D. , Laguerie C.
Published: March 2009

The behaviour of a fluidized bed reactor for the catalytic oxidation of benzene to maleic anhydride has been studied following a 24 factorial design of experiments. Results stand comparison with those observed in fixed bed reactors. Yields as high as 42% are obtained.

Statistical analysis of the data, using the Yates method, to establish the polynomial dependence of conversion, selectivity and yield on the operating variables (temperature, benzene/air ratio, volumetric flow of the feed, height of the catalytic bed of particles) shows that the performance of the system, for each response, can be translated to an incomplete quadratic model with only limited interactions among the variables. Although it is difficult to establish a precise correspondance of the parameters of the models to the fundamentals of fluidized bed reactors, some of the phenomenological principles of the process related to conversion and selectivity have been identified. However, such is not the case for the unusually complex yield response. The analysis of the data suggested a more refined control of the variables to elucidate the behaviour of the yield around the optimal operating conditions.
Traitement du sable bitumineux par micro‐ondes
Authors: Cambon J.L. , Klvana D. , Chavarie C. , Bosisio R.G.
Published: March 2009

Un traitement micro‐ondes a été utilisé dans le but de dégager les hydrocarbures présents dans le sable bitumineux, II a été constaté que les micro‐ondes provoquaient une distillation et un craquage du bitume. La dépendance du taux d'extraction du bitume a été évaluée pour les facteurs suivants: temps de traitement, intensité du champ micro‐ondes, débit et nature du gaz de balayage, forme et position de l'échantillon dans le champ micro‐ondes. Les résultats obtenus ont permis de dégager d'une part un mécanisme de chauffage et d'autre part des conditions opératoires pour l'utilisation optimale des micro‐ondes pour le traitement du sable bitumineux.
The thermal conductivity of porous catalyst pellets
Authors: Soomro M. , Hughes R.
Published: March 2009

Thermal conductivities of γ‐alumina and alumina supported nickel catalysts prepared by impregnation and coprecipitation have been measured by a transient method. Results obtained were compared with predictive models and it was found that a simple modification' of a one parameter model gave good agreement with the results for the support and impregnated catalysts but did not give satisfactory predictions for the coprecipitated catalyst.
Rates of extraction of mercaptan sulfur from pentane by caustic solution
Authors: Carr N. L. , Shah Y. T.
Published: March 2009

The interphase rate process for the extraction of mercaptan sulfur from n‐pentane with a 10% caustic solution is examined. The system represents a case of mass transfer with an equilibrium chemical reaction occurring in one phase. Experimental studies were made with both a continuous flow stirred tank reactor (CFSTR) and an annular flow jet reactor (AFJR). The interphase volumetric mass transfer coefficient (KLa) was derived based on Olander's theory. The KLa data for each contactor was found to be a function of the power input per unit volume. The AFJR exhibited higher KLa values and equilibration of mercaptan sulfur was achieved in about three milliseconds.
Internal mass transfer coefficient within single bubbles. Theory and experiment
Authors: Zaritzky Noemi E. , Calvelo Alfredo
Published: March 2009

Mass transfer coefficients inside single rising bubbles are measured in the system SO2, N2—H2O by using a photographic technique.

The differential equations which govern the phenomena, including internal toroidal circulation inside the bubble, are also presented. Assumptions are incompressible, steady, irrotational outside flow and inviscid, steady, axisymrnetric inside flow.

From the mass transport viewpoint, restrictions are: binary dilute mixture and axial symmetry.

The theoretical solution is presented as Sh vs. Pe and a comparison with experiments shows good agreement.

Theoretical predictions for a stagnant fluid inside the bubble were also compared with the experimental results.
Kinetics of decarburization of molten fe‐c by gaseous hydrogen
Authors: Whiteway S. G.
Published: March 2009

Hydrogen was directed onto the surface of Fe‐4%C held in an Al2O3 crucible at 1327°C, and the rate of formation of CH4 was measured by mass‐spectrometric analysis of the effluent. The measured rate approached the theoretical limit of mass transfer of CH4 in the gas phase, provided that the concentration of other gases evolved by side‐reactions was small. Deviations from predicted values appeared to be caused by carbon monoxide coming from the reaction of dissolved carbon with the crucible, and water coming from the reaction of hydrogen with the refractories. The gas mass transfer coefficient for the particular geometry used was determined in separate experiments where the carbon was oxidized by CO2.
On the use of residence time distributions for the design of clarifiers
Authors: Silveston P. L. , Stepko W. A. , Sakata N. , Cordoba‐Molina J. F. , Rietema K. , Hudgins R. R.
Published: March 2009

Use of residence time distributions (RTD's) for the design of clarifiers proposed by the senior author in 1969 and by others has been found to be based on flow pattern assumptions which are false. Since the residence time distribution depends upon the density of the feed to the clarifier, flow rate and other near‐intangibles, it is not possible to obtain RTD's which pertain to an operating settler from which reliable performance may be predicted. Finally, laboratory studies demonstrate that the combination of RTD's and quiescent settling data do not reliably predict clarifier performance.
An analysis of the viscous behaviour of polymeric solutions
Authors: Carreau P. J. , Kee D. De , Daroux M.
Published: March 2009

Viscosity data of an aluminum soap solution, a polyisobutylene solution, a polyacrylamide solution, and ten polystyrene solutions have been analysed using two rheological models: the Carreau model A and the Ellis model. The model parameters were obtained by non‐linear regression. The importance of the zero‐shear viscosity for design purposes is illustrated by observing the appearance of a master curve in the representation of the dimensionless viscosity versus the product of the zero‐shear viscosity by the shear rate. A linear relation is shown to exist between the logarithm of the zero‐shear viscosity and the polymer concentration. It is asserted that either model should replace advantageously the commonly used power‐law expression.
Absorption of oxygen by aqueous sodium sulphite solutions
Authors: Sathyamurthy N. , Degaleesan T. E. , Chandrasekharan K. , Laddha G. S.
Published: March 2009

New data have been reported on the absorption of oxygen by aqueous sodium sulphite solutions with cobalt sulphate as catalyst at 30°C. It is observed that the absorption rate increases up to a critical sulphite concentration beyond which the absorption rate becomes constant and this critical concentration varies with the catalyst concentration. The order of reaction with respect to sulphite and oxygen in the constant absorption rate regime was found to be zero and two respectively. The absorption rate is affected by the total ionic strength (sulphite and sulphate) in addition to the effect of pH and catalyst concentraion. The reported data were also analysed to ascertain the effect of temperature and a relationship has been proposed for prediction of the second order reaction rate constant.
Corrosion product transport in water‐cooled nuclear reactors. Part III: Boiling water with indirect cycle operation
Authors: Burrill K. A.
Published: March 2009

Corrosion products from out‐core surfaces are made radioactive when deposited in the core of a water‐cooled nuclear power reactor. Their release and deposition on out‐core surfaces causes gamma radiation fields to grow with time around these surfaces.

Deposition and release of corrosion products in the reactor core is strongly influenced by the mode of heat transfer and by the water chemistry. Here, the deposition of corrosion products from boiling water onto nuclear fuel sheaths was studied in a water loop and in the CANDU Nuclear Power Demonstration (NPD) reactor as a function of possible water chemistries for indirect cycle operation. Deposits on sheaths in the boiling water region of test sections were very heavy (35 g Fe/m2) when ammonium hydroxide at 10 to 20 mg NH3/kg controlled the pH, or when the pH was controlled with 0.02 mg Li/kg added as LiOD. Deposits were light (∽ 50 mg Fe/m2) if the pH was controlled with at least 1 mg Li/kg. A mathematical model for deposition and release of corrosion products at fuel sheaths in non‐boiling water was modified and found to apply also in boiling water for the high pH test.
Metal recovery from coal ash via chlorination — A thermodynamic study
Authors: Mehrotra Anil K. , Bishnoi P. R. , Svrcek W. Y.
Published: March 2009

Coal ash can become an important mineral substitute for the recovery of several metals, especially aluminum and titanium. A plausible route for the recovery could be via high temperature chlorination in the presence of a reducing agent. The thermodynamics of the reaction system for the free energy computations consisted of 135 chemical species containing 12 elements, namely Al, C, Ca, CI, Fe, K, Mg, Na, O, S, Si and Ti. The results indicate that the chlorination route is feasible over a wide temperature range.
Comparison of the product distribution in the catalytic cracking of dewaxed neutral distillate over lanthanum‐exchanged X and Y type zeolites
Authors: Yeh Jer‐Jeng , Wojciechowski B. W.
Published: March 2009

A comparison of the selectivity for minor products formed from the same feedstock on LaX and LaY has shown that the two catalysts differ very little in their conversion of the feed. There is, however, a marked difference between the two catalysts in their activity toward short chain product olefins. These are rapidly saturated, cracked or turned to coke by the X catalyst.
Generalized dehydration models for n‐Aliphatic monohydric alcohols
Authors: Abhyankar S. M. , Doraiswamy L. K.
Published: March 2009

The kinetics of dehydration of n‐aliphatic monohydric alcohols (viz. ethyl, n‐butyl, n‐hexyl and n‐octyl) has been studied over Indian bauxite as catalyst in the temperature range 300–375°C. Modified Hougen‐Watson models for all the four reactions occurring have been proposed, and the rate and adsorption constants have been estimated by the method of linear least squares, and confirmed by nonlinear analysis. Generalized correlations for predicting the rate constants on the basis of change in the entropy of activation have been developed. Similarly, correlations have also been developed for each of the adsorption constants as a function of the binding energy of the alcohol molecule involved.
Vapor‐liquid equilibria for the ternary system n‐Heptane/n‐Propanol/l‐Chlorobutane and its constituent binaries at 298.15 K
Authors: Sayegh S. G. , Vera J. H. , Ratcliff G. A.
Published: March 2009

Vapor‐liquid equilibrium data for the ternary system n‐heptane/n‐propanol/1‐chlorobutane and its constituent binaries at 298.15 K are reported. Data for the binary systems have been correlated using the Wilson, LCG, LSG and UNIQUAC expressions for the activity coefficients. Predictions for the ternary system with all four expressions have been compared with the experimental data. The Wilson and the LCG equations perform similarly, giving the best correlations for the binary systems containing propanol and the best predictions for the ternary system.
Evaluation of capital cost data: Offsite utilities (Supply)
Authors: Woods Donald R. , Anderson Susan J. , Norman Suzanne L.
Published: March 2009

Capital cost correlations are given for units supplying utilities: steam, refrigeration, cooling and treated water, electricity. Correlations available in the literature and current data are compared on a consistent basis. Thirty‐two graphs show the relative magnitudes of the different correlations, and the recommended correlation for each type of equipment is given. Some factors are given on the costs of installing the package units.
Fundamental studies of foam fractionation of cadmium: Effect of the addition of monovalent ions on surface excess of cadmium
Authors: Kubota K. , Hayashi S. , Takubo Y.
Published: March 2009

The effects of Sodium, Cadmium and Hydrogen ions on the surface excess of the collector, Dodecylbenzenesulfonic group, DBS”, were examined using an elaborated Langmuir correlation. Gouy‐Chapman's electrical diffuse layer model for estimating the cations, colligend ions, Cadmium and Sodium ions, to be concentrated on a bubble surface was found to be applicable for the aqueous CdCl2‐DBSNa, Cd(NO3)2‐HNC2‐DBSNa and CdCl2‐HCl‐DBSNa solution systems. The behaviour of Sodium ion in the diffuse layer and the selective adsorption coefficient for the solution system containing Cadmium and Sodium ions was also studied, showing a preferential adsorption of divalent ion in the diffuse layer.
The oxidation of ethylene over a supported platinum catalyst
Authors: Hawkins James R. , Wanke Sieghard E.
Published: March 2009

The complete oxidation of ethylene over a 0.3% Pt/Al2O3 catalyst, at ethylene concentration of ≤ 1.0 mol/m3 and oxygen concentrations of 0.16 to 8.6 mol/m3, was studied in a recycle reactor at temperatures of 362 to 472 K. The activity of the catalyst was influenced by pretreatment and reaction conditions causing fluctuations in rate measurements. Nevertheless, a simple rate function, r =Ae−E/RT[O2]/[C2H4], fitted the data as well as more complicated rate functions.
Déformation et oscillation des gouttes en présence d'agents tensio‐actifs
Authors: Mekasut L. , Molinier J. , Angelino H.
Published: March 2009

A study was made of the fall of a single drop of carbon tetrachloride through pure or contaminated water. Results are presented for the variations of the shape of the drop and of the frequency of oscillation with diameter and Teepol concentration. It has been found that presence of surface active agents, increases the deformation of drops but reduces the frequency of oscillations. The comparison between these experimental data and several relations has shown that no previous correlations of either the eccentricity or the frequency of oscillation are satisfactory when the system is contaminated by some surfactants.
Rates of gas absorption with interfacial turbulence caused by micro‐stirrers
Authors: Sada Eizo , Katoh Shigeo , Yoshii Hwehumi , Ban Yuji
Published: March 2009

Rates of absorption of CO2 into water, a 0.2 mol/L NaOH solution and a 40 wt% glycerol solution with and without the interfacial turbulence caused by micro‐stirrers, made of a magnetic material, were measured with use of a stirred vessel with known gas‐liquid interfacial area. The effect of the interfacial turbulence on the rate of gas absorption was remarkable in the lower range of the bulk turbulence. The enhancement factors due to the interfacial turbulence were calculated with use of the age distribution function of the Danckwerts type and they agreed well with the experimental results.
Modèles cinétiques et mécanisme de l'oxydation catalytique. Du propene en présence de molybdate de fer
Authors: Forissier M. , Gros J. B. , Pralus C.
Published: March 2009

The kinetic study of propylene oxidation to acrolein over a ferric molybdate catalyst has been performed on a differential reactor. Among models derived on the assumptions of Langmuir Hinshelwood kinetic rate or on Mars and Van Krevelen oxido‐reduction mechanism, a discrimination method has been realized. The discrimination leads on one hand to the conclusion that acrolein is obtained either from oxygen of the oxide lattice or from absorbed dissociated oxygen. On the other hand carbon dioxide is formed both by acrolein degradation and by a mechanism excluding dissociation of oxygen.
Macro‐encapsulation I. Production of composite drops
Authors: Aboul‐Nasr Osman T. , Huang Robert Y. M.
Published: March 2009

A method for the production of concentric drops is presented in detail. The apparatus consists of two coaxial nozzles at the bottom of a column, and the necessary pumping equipment. Two immiscible liquids arc pumped individually through the nozzles. The resultant drop is allowed to rise through a column of liquid immiscible with the outer drop.

Details of the experimental procedures and results are presented. A theoretical model describing the behaviour of the system, based on the hydrodynamics of drop formation, is developed.

The production of composite drops can be applied to many products, for example: sustained delivery of drugs and time‐release fertilizer.
Hydrocracking athabasca bitumen with alkali metal promoted CoO‐Mo03‐A12O3 catalysts
Authors: Kelly James F. , Ternan Marten
Published: March 2009

Alkali metal promoters (lithium, sodium and potassium) were added to catalysts used to hydrocrack Athabasca bitumen, in order to decrease the coke deposition which causes catalyst deactivation. Sodium and potassium promoters decreased the catalyst coke content, the catalyst surface area, and the pitch, oxygen, sulphur and nitrogen conversions. On a unit surface area basis, the sodium and potassium promoters increased the pitch and oxygen removal reaction rates. For all the lithium promoted catalysts both conversion and pitch, oxygen, sulphur and nitrogen removals on a unit surface area basis exhibited a maximum. Sulphur and nitrogen removal decreased with increasing potassium content. The results are explained in terms of the changes in catalyst electronic properties caused by the addition of the promoters.
A novel magnetoelectrolytic reactor
Authors: Ismail M. I. , Fahidy T. Z.
Published: March 2009

The characteristics of mass transport and cathode deposit in a pilot‐plant size magnetoelectrolytic reactor employing an anisotropic inhomogencous magnetic field are analyzed. It is shown that the behaviour of the reactor, especially the deposition pattern, is strongly linked to the distribution of the magnetic flux density.
Numerical and experimental study of a falling liquid column
Authors: Hill G. A. , Chenier C. L. , Shook C. A. , Esmail M. N.
Published: March 2009

The collapsing liquid column phenomenon has been experimentally and theoretically studied. The experimental data demonstrated the development and travel of a shock wave. Point velocities within the flow regime were measured using a hot film probe. The numerical simulation was performed using a finite difference code similar to the Marker and Cell technique. The results were in good agreement with the experimental data. The numerical technique therefore promises to be a valuable aid in studying highly convective, incompressible flows.
Measurements of interfacial areas in cocurrent gas—liquid downward flow
Authors: Vavruska J. S. , Perona J. J.
Published: March 2009

Gas‐liquid interfacial areas were measured for cocurrent downward flow of the two‐phase mixtures in a 2.54 cm ID open tube. The liquid phase was a dilute solution of aqueous sodium hydroxide and the gas phase was a mixture of air and carbon dioxide. Interfacial areas were determined by sampling the liquid phase and applying the technique of absorption with fast chemical reaction. Data were obtained in the froth flow regime and in the falling bubbly film regime which does not occur in horizontal or vertical upflow. Measured interfacial areas ranged from 0.7 to 2.5 cm−1. These values are lower than those for downflow in a 10‐mm tube(10) by a factor of about two, suggesting a dependence on the tube diameter. A correlation in terms of Jepsen's frictional energy dissipation parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\frac{{\Delta P}} {{\Delta L}}} \right)(V_L ^ \circ + V_G ^ \circ ) $\end{document} is presented for the interfacial area.
Energy balance for a DC plasma torch
Authors: Bokari Azhar , Boulos Maher
Published: March 2009

A study was made of the energy utilization efficiency in a d.c. plasma toich operating with argon at atmospheric pressure at a power level of 10‐25 kW. Calorimetric measurements of the energy lost to the cathode, anode and that remaining in the plasma jet showed that the torch efficiency was about 40 to 50%. It increases with an increase of the plasma gas flow rate but decreases with an increase of the current intensity. The electrode spacing was found to have no significant influence on the efficiency over the range investigated. The torch efficiency could be substantially improved by a reduction of the anode size. The addition of small concentrations of a diatomic gas such as nitrogen improved the efficiency to about 65% and increased the total power dissipated in the torch.
Isothermal column sorption of ethylene—carbon dioxide mixtures with azeotropic behaviour
Authors: Basmadjian D. , Hsieh S. T.
Published: March 2009

Isothermal breakthrough curves were determined for ethylene‐carbon dioxide mixtures in nitrogen fed to a bed of Linde 5A 1/8″ molecular sieve pellets. The system had previously been shown(11) to have azeotropic equilibrium compositions in the range − 50 to + 50°C and at a total solute pressure of 1.07 kPa. The present column experiments covered the range −15 to + 50°C and total solute pressures of 0.40 ‐ 2.67 kPa. Three major types of adsorption breakthrough curves were observed. In two of these the solutes broke through simultaneously and could not be separated by extending the bed length. Carbon dioxide exceeded and then dropped back to the feed concentration in some of these runs, in others the inlet value was reached directly. In the third type of curve, the sorption fronts did separate, but the light component did not always exceed the feed concentration in the classical manner of a Langmuir solute. A tentative explanation of these phenomena is given in terms of equilibrium theory.
Activated carbon adsorption treatment of spent pickle brine
Authors: Ratnani Kebir , Leduy Anh , Ramalho Rubens S.
Published: March 2009

A continuous process for recovery of spent pickle brine (SPB) by preliminary filtration on a sand bed to remove suspended solids, followed by adsorption treatment in an activated carbon column to remove color and odor‐causing organic compounds is investigated. Batch isotherm adsorption experiments revealed that the adsorption capacity of the SPB‐activated carbon system is relatively insensitive to temperature variation (about 15% drop for a temperature rise from 0 to 40°C), but quite sensitive to the effect of dilution (about 25% lower for 90% SPB solution). Regenerated activated carbon behaved similarly to fresh carbon with only slightly lowered adsorption capacity. It is estimated that a low capital investment of 0.08 cent per liter of recycled treated SPB is required for a plant with a 190 000 L/d capacity. This cost is much lower than that of fresh salt, and thus will be defrayed by savings on recycled salt.
Cristallisation du trihydrate d'alumine: Effet des conditions d'agitation
Authors: Remillard Michel , Cloutier Leonce , Methot J. Claude
Published: March 2009

La cristallisation du trihydrate d'alumine a été étudiée pour différents niveaux d'agitation dans un réacteur isotherme fonctionnant en régime discontinu. Les essais expérimentaux ont permis de relier aux conditions d'agitation les constantes cinétiques de trois phénomènes se produisant lors de la cristallisation de l'alumine. Finalement, des calculs de simulation ont permis de noter qune importante amélioration de la précision sur les granulométries est obtenue en ajoutant les modèles d'agglomération et d'attrition au modèle déjà connu de croissance.
Unsteady stagnation point heat transfer in non‐newtonian fluids
Authors: Gorla Rama Subba Reddy
Published: March 2009

The transient thermal response of a power law type non‐Newtonian, laminar boundary layer at a two‐dimensional stagnation point is investigated. Consideration is given to the case of a step change in surface temperature. The transient heat flux and details of the temperature field are obtained and have been presented graphically. The range of Prandtl numbers investigated is from 5 to 1000 while the viscosity index was allowed to vary from 0.1 to 5.0.
Laminar natural convection over a slender vertical frustum of a cone with variable surface temperature
Authors: Chiou J. P. , Na T. Y.
Published: March 2009

The problem of laminar, natural convection flow over a slender frustum of a cone with variable surface temperature is treated in this paper. The governing differential equations are solved by a combination of quasilinearization and finite‐difference methods. As an illustration of the formulation, numerical solutions are obtained for a range of Prandtl numbers (0.1 to 100) and the transverse curvature parameter for the case of power‐law surface temperature distribution. The formulation presented in this paper provides a way to analyze the heat transfer over a slender frustum of a cone where both the transverse curvature and the surface temperature variation have to be considered simultaneously.
Gas‐Liquid reactions in packed beds: Regimes of reaction in the static hold‐up
Authors: Patwardhan V. S.
Published: March 2009

The interfacial area in a packed bed may be divided into two parts, i.e. the interracial area corresponding to the dynamic hold up, and that corresponding to the static hold up. Although both these parts contribute towards gas absorption, the effectiveness of the interfacial area of the static hold up in a packed bed for gas absorption with a chemical reaction can become quite low (which leads to a reduction in the effective interfacial area) if there is a significant depletion of the liquid phase reactant in the static hold up. If this depletion is severe enough, then the chemical reaction in the static hold up may fall into the slow reaction regime, i.e. unreacted gas phase component may exist in the bulk of the static hold up. In this paper, a general procedure is developed for calculating the effective interfacial area in a packed bed which is applicable for all possible reaction regimes that may exist in the static hold up. An approximation is proposed for cases involving the slow reaction regime in the static hold up. This approximation is applicable to reactions with any form of kinetics. It is shown to predict the effective interfacial area with sufficient accuracy in the case of a second order reaction.
Statistical study on the batch conversion of estevan lignite into oils using carbon monoxide and hydrogen mixtures
Authors: Fonseca R. , Chornet E. , Roy C. , Grandbois M. , Kelly James F.
Published: March 2009

Batch autoclave hydrogenolysis of a Saskatchewan lignite has been conducted with CO and H2 mixtures. Conversion, oil yield and the carbon monoxide consumption patterns were measured as a function of reaction temperature (380 — 460°C), initial cold pressure (7.1 — 11.1 MPa), contact time (10 — 50 min), and initial CO/H2 gas composition (1/3 — 3/1 vol. %). The experimental results were obtained following an unreplicated 24 factorial design. Significant models were derived for conversion and the CO consumption patterns. A relationship seems to develop between carbon monoxide consumption and the amount of oil produced. The oil yield model however showed a lack‐of‐fit at the F5% level. The highest conversion and oil yield experimentally obtained were 85.3 and 63.4% respectively, on the lignite m.a.f. basis. In general greater hydrogenation but less deoxygenation occurred at the lower temperature.
Mass transfer rates between oil slicks and water
Authors: Cohen Yoram , Mackay Donald , Shiu Wan Ying
Published: March 2009

The results of a laboratory wind‐wave tank study are reported in which the rate of mass transfer of a tracer (phenol) from a synthetic oil slick to the underlying water was measured at wind speeds from 0 to 9 m/s. Estimates were made of the mass transfer coefficients in the oil and water phases at the oil‐water interface. The results indicate that the rate of hydrocarbon dissolution from a slick is controlled by the water phase mass transfer coefficient which is usually less than 1 cm/h. Whereas mass transfer coefficients at air‐water interfaces show a marked increase at wind speeds of approximately 3 m/s due to wave formation, when oil is present its damping effect delays this transition to approximately 7 m/s. It can be inferred that (i) dissolution is considerably slower than evaporation for reasonably volatile compounds, (ii) dissolution will have a negligible effect on slick composition, (iii) the concentrations of soluble hydrocarbons established in the water column under the slick by direct dissolution are small and unlikely to result in significant toxicity, and (iv) that the dominant mechanism of transfer of soluble hydrocarbons into the water column is probably from dissolution of dispersed oil particles.
Study of chromia alumia catalysts
Authors: Mathur Indresh , Bakhshi Narendran N. , Mathews Joseph F.
Published: March 2009

The purpose of this study was to investigate the effect of increasing chromium concentration on the activity and physical properties of chromia/alumina catalysts. The catalysts were prepared by impregnating η‐alumina support in various concentrations of chromic acid solution and were finally calcined in air.

A variety of physical‐chemical properties of the catalysts were studied. These included BET surface area, pore volume, metal concentration, x‐ray diffraction studies, oxidation states using EPR, surface oxidation (excess oxygen) measurement by iodometric titration, metal area measurement and crystallite size determination. Decomposition of hydrogen peroxide was used to determine the activity of various catalysts.

A correlation of catalytic activity with crystallite size indicated that both, activity per unit chromia area and activity per g of catalyst were maximum at a crystallite size of 3.7 mm. Also, the activity per unit chromia area is maximum when chromia is deposited 3‐4 layers thick.

In contradiction to the view put forth in the literature, this study indicates (on the basis of excess oxygen and chemisorption measurement) that not only is all of the top chromium oxidized to Cr6 but that the oxidation also takes place in the sub‐surface layer(s).
Statistical identification of a reaction network using an integral plug flow reactor
Authors: Mclean David D. , Bacon David W. , Downie John
Published: March 2009

Statistical multiresponse techniques for the design and analysis of experiments were used in conjunction with an integral isothermal staged tubular reactor to identify the reaction network for the oxidation of o‐xylene over a V2O3/K2SO4/silica catalyst. Following a five stage strategy a precise quantitative description of the reaction network in terms of the multiresponse form of the steady state adsorption model was obtained. The use of mixed feeds was found to improve the precision of rate parameters associated with later steps in the reaction network and also to reduce correlations among estimates of the rate parameters.
The nature of the active sites in the reactions of cumene on HY and LaY catalysts
Authors: Corma A. , Wojciechowski B. W.
Published: March 2009

The secondary reactions which accompany cumene cracking have been studied at 360°, 430°, 500°C, over an HY zeolite catalyst using a tubular packed bed reactor. The concept of “Optimum Performance Envelope” was used in order to identify which of the observed reaction products are primary and which are secondary. In this way, benzene, ethylbenzene, n‐propylbenzene, cymene, m‐ and p‐diisopropylbenzene, as well as propylene, i‐butene, and butene have been found to be primary products, while methane, ethylene, ethane, toluene, ethyl toluene, and i‐ and n‐butane are identified as secondary products.

The initial selectivities for the primary products have been calculated, and from these, the initial kinetic rate constants. These values, as well as the activation energies of primary product formation, are compared with those obtained using a LaY zeolite catalyst. The observed differences are discussed in terms of the nature and number of the active sites on the catalyst and lead us to conclude tthat LaY and HY have identical active sites but differ in site concentration.
Velocities of entrainment in liquid fluidized beds of mixed solids
Authors: Vaid R. P. , Gupta P. Sen
Published: March 2009

Experimental data are reported on velocities of entrainment in liquid fluidized beds. Single as well as multicomponent mixtures of solids varying in size and/or density have been investigated. By drawing an analogy with partially fluidized bed systems, phase equilibrium diagrams of binary and ternary mixtures have been constructed and presented. Correlations have been developed for the prediction of velocities related to the beginning of entrainment, minimum entrainment and complete entrainment.
Anodic oxidation of phenol for waste water treatment
Authors: de Sucre V. Smith , Watkinson A. P.
Published: March 2009

The electrochemical oxidation of phenol for waste water treatment applications was investigated on lead dioxide packed‐bed anodes. Cells were operated in both batch and continuous modes with feed streams up to 1100 nig/1 phenol dissolved in aqueous solutions of Na2SO4 and H2SO4 or NaOH. All the phenol in solution could be readily oxidized but complete total organic carbon (T.O.C.) removal was more difficult. The percent phenol oxidized increased with increasing current density, and decreased as initial phenol concentration, electrolyte flow rate, pH and anode particle size were increased. Results are compared to simple mathematical models.
Étude des isothermes d'Adsorption de surfactants ioniques et non ionique sur des fibres de laine carbonisée
Authors: Perineau Francis , Molinier Jacques , Gaset Antoine
Published: March 2009

The adsorption isotherms of the three main types of surfactant have been plotted against various pH's and temperatures. It has thus been possible to propose new ways of insuring adsorption and determining the importance of the ionic links and hydrophobic interactions involved in the various‐medium conditions considered. The presentations by Lauginuir and Freundlich have permitted to develop the adsorption equations corresponding to each case. Finally, the isotherm plotting in a series of low concentrations has permitted to predict the maximum volume of an effluent purified per kilogram of substrate, in the case of the concentrations frequently found in the waste waters.
A method for reducing the deposition of small particles from turbulent fluid by creating a thermal gradient at the surface
Authors: El‐Shobokshy M. S.
Published: March 2009

The present paper suggests the use of thermophoretic phenomena to decrease the rate of particle deposition onto pipe walls from a turbulent flow. When a tube is externally heated; the particles will be subjected to thermal force within the laminar sublayer in a direction away from the surface preventing or reducing their deposition. A theory proposed by EI‐Shobokshy and Ismail (1980) has been used for estimating the deposition velocity. The thermal velocity component was calculated and the effective velocity of particles approaching the wall surface computed. The results present the relationship between particle penetration and particle size at different values of pipe wall temperature and Re. The experimental results showed a good agreement with theoretical results for particle sizes 6 ‐10 μm diameter, Re = 6000 – 8000 and pipe wall temperatures 50 – 150°C.
Modelling radiation interception by strongly clumped vegetation — a combined monte‐carlo and analytical model
Authors: Whitfield D. W. A.
Published: March 2009

The study of solar radiation penetration into plant stands is important to studies of energy balance and photosynthesis. A large literature deals with horizontally uniform canopies of random leaf placement, in which a simple model based on Poisson statistics accounts for the probability, P(z), of ray penetration without interception to depth x: P(z) = exp [‐k(η)A(z)/cosη] where η is the ray origin zenith angle, k depends upon the distribution of leaf orientations and A(z) is leaf area per unit ground area to depth z. When leaf location is either clumped or regular other statistical models are applied. These, unlike the above model, require the empirical determination of parameters by fitting to interception data. More extreme clumping, into isolated plants or hedgerows, has been handled by calculating ray path lengths through the stand within an envelope defining the plant shape and applying the above model for uniform random leaf arrangement along these parts of the paths. For regular arrangements of uniform sized plants this is a matter of straightforward but lengthy calculation. The problem considered here, of randomly placed plants of non‐uniform size, cannot be treated by the same method. To determine within‐plant pathlengths, the intersection points of randomly chosen rays with the outlines of plants were first computed, then the above model was applied along each within‐plant path and the results of many rays from each direction were averaged. There are no parameters to be empirically fitted. Results are presented for cylindrical, conical and spherical plant outlines.
Laminar falling film flow and heat transfer characteristics on horizontal tubes
Authors: Rogers J. T.
Published: March 2009

Knowledge of falling film flow and heat transfer characteristics on horizontal tubes is required in the assessment of certain CANDU reactor accident sequences for those CANDU reactors which use moderator dump as one of the shut‐down mechanisms. In these reactors, subsequent cooling of the calandria tubes is provided by falling films produced by sprays. This paper describes an analysis of falling film flow and heat transfer characteristics on horizontal tubes using integral methods. The application of the results to an assessment of the stability of the films on the calandria tubes following a loss‐of‐coolant accident with impaired emergency coolant injection flow is discussed.
Development of a monitoring system for Ash deposits on boiler tube surfaces
Authors: Chambers A. K. , Wynnyckyj J. R. , Rhodes E.
Published: March 2009

The etfect of ash deposits on the output of heat flux meters installed on the water wall tubes in pulverized coal fired utility boilers is studied. The objective is to use commercially available heat flux meters as the sensing devices for detecting and monitoring the growth of ash deposits. Reliable performance is shown and an attractive method is described for processing the heat flux meter output into a signal related to the ash deposit only and independent of variation of boiler load and firing conditions in the combustion chamber. Patents are pending for this Monitoring System.
Prediction of error estimates for thermocouple attached to a surface using differential inequalities
Authors: Martin W. W. , Lyn D. A.
Published: March 2009

An analysis is proposed to estimate the measurement error when determining the temperature of a surface with an attached thermocouple. The sensing element is assumed to be a point in a domain that is a circular segment of an infinitely long cylinder. The temperature distribution in the segment which models the medium used to attach the thermocouple is found approximately by using an embedding technique and the method of weighted residuals. The construction of bounds on the unknown exact solution is outlined and results are presented for Biot numbers up to 10.
Heat transfer to wires and cylinders in high‐temperature surroundings
Authors: Sayegh N. N. , Gauvin W. H.
Published: March 2009

This paper presents an extension to the case of wires and thin cylinders of a theoretical analysis previously reported by the authors to account for the effects of large temperature differences and large variations of the fluid property on the heat transfer process to a sphere exposed to a gas at very high temperatures.

Two concepts were used in this theoretical derivation: (i) the use of a limiting Nusselt number at Re = 0, as derived from the energy equation, and (ii) the use of a reference film temperature for the evaluation of the Reynolds number different from that used for the Nusselt number. The predictions of this analysis are shown to be in excellent agreement with published experimental data in the Re range 0.01 to 40, when the ratio of the wire to the free stream temperature exceeds 0.4. This range of operating conditions is frequently encountered in industrial plasma processing and in certain high‐temperature chemical engineering operations.

Measurements in argon and chlorine plasma tailflames with temperature differences exceeding 2000 K are described.
The effect of fin conductance on laminar heat transfer characteristics of internally finned tubes
Authors: Soliman H. M.
Published: March 2009

An analytical solution for the temperature distribution and Nusselt number during fully developed laminar flow in internally finned tubes is obtained taking into consideration the realistic situation of fins with finite thermal conductivities. Axially uniform heat flux and circumferentially uniform temperature are assumed at the outer surface of the tube. For any tube geometry, it was found that the heat transfer characteristics are influenced by a single parameter K, which is directly related to the angle subtended by the fin, and the thermal conductivities of the fluid and the fin material. Nusselt numbers corresponding to different values of K are presented for a range of tube geometries
Coherent particle oscillation in fluidized beds
Authors: Broadhurst T. E. , Becker H. A.
Published: March 2009

Very shallow gas‐fluidized beds, typically under 0.1 column diameters in settled depth, exhibit coherent particle oscillations, also manifested by regular pulsations in bed height. This phenomenon has been studied experimentally and correlations have been developed for the oscillation frequency and the maximum bed height. The results give qualified support for the theories of Hiby and Verloop and Heertjes, but needs for improvement in the theoretical approaches and for more experiments are also evident. In particular the effects of column diameter, distributor resistance, and plenum volume need systematic study in order to answer questions raised by our work, a theoretical suggestion by Davidson, and results of Baird and Klein for an adjacent operating regime.