bluuebunny/crossref_metadata_2025 huggingface dataset:
The kinetics and mechanism of the oxidation of carbon monoxide over an industrial vanadium oxide catalyst
Authors: Mann R. F. , Tycholiz D. , Stanislaus A.
Published: March 2009

The rate of catalytic oxidation of carbon monoxide was studied in a fixed bed reactor over the following range of conditions: 325 to 396°C, 0.11 to 1.75 mole % oxygen, 9.50 to 10.20 mole % carbon monoxide. Oxygen was the limiting component, most of the runs were taken to greater than 10% oxygen conversions, and therefore an integral approach was taken in the data analysis. The catalyst was vanadium oxide/potassium sulfate on silica, an industrial preparation which had been used in previous kinetic studies.

The data were correlated successfully by the steady state adsorption model with Arrhenius activation energies of 22.1 k.cal/g. mole for the oxygen chemisorption step and 18.0 k.cal/g. mole for the reaction step.

The rate constants obtained provide further support for the steady state adsorption model, previously used to evaluate the oxidation kinetics of naphthalene, toluene, benzene and orthoxylene on the same catalyst. The integrated rate equation appears to well describe the relationship between the various parameters with the conversion of the limiting component varying from less than 5% to over 50%.

A brief comparison is reported between the steady state adsorption model and the more complex triangular mechanism postulated by Hirota and co‐workers.
Elimination of initial conditions in linear dynamic batch process identification by least squares
Authors: Xuyen V. T. , Svrcek W. Y.
Published: March 2009

The requirement of data from many batch runs and the need to estimate initial conditions for each batch complicate dynamic batch process identification. However, when the model used to represent the dynamics is linear in the state vector, utilization of Lawton's and Sylvestre's idea avoids direct‐estimation of the initial conditions for each batch. This simplification permits an approximate on‐line identification procedure to be developed to update the model as data from each new batch are received.
Laminar transient flow in pipes
Authors: Masliyah J. H. , Shook C. A.
Published: March 2009

The effects of fluid viscosity, pipe length, radius and pressure wave celerity are examined by solving the equations of fluid motion numerically for impulsively started flows. Velocities are obtained in terms of axial and radial positions and time. Pressures are obtained as a function of axial position and time using an averaging process. The dimensionless group \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{\rho a{\rm R}^2}}{{\mu {\rm L}}}$\end{document} is shown to determine the development of these profiles.

At low values of this group, a significant axial variation in the velocity profiles occurs. The pressure fluctuations accompanying startup however are progressiveely more damped as this group decreases. Such fluctuations are shown theoretically and experimentally to disappear when the aforementioned group falls to about 1.6. The numerical method used is capable of being applied to other transient pipe flows.
Behavior of macromolecules in dilute solutions: II—On the axial dispersion coefficient
Authors: Chen H. R. , Blanchard L. P.
Published: March 2009

Using pulse‐input technique, axial dispersion coefficients were determined for polystyrene in tetrahydrofuran, in toluene and in a toluene/methanol mixture flowing in a long capillary tube under conditions such that the Reynolds number was less than 500. Low polydispersity polystyrene materials with nominal molecular weights ranging from 900 to 1.8 × 106 were used. For the system studied and for fixed Reynolds numbers, the coefficient, on log‐log scales, was found to be a linear function of the product of the intrinsic viscosity and the molecular weight. An empirical equation relating this coefficient to the Reynolds number and to [η]M was obtained. This equation predicted results which agreed well with experimentally determined values.
The vaporization of small binary drops on a flat plate at maximum heat flux
Authors: Mann R. F. , Walker W. W.
Published: March 2009

The vaporization times of small (12 mg.) drops of a binary liquid on a flat plate were measured in the maximum (critical) heat flux region of boiling heat transfer. The binary system studied was water‐1‐pentanol, the mixture previously shown by other workers to exhibit the most pronounced concentration effect on critical heat flux. Evaporation curves are reported in the critical region for pure water, pure pentanol and a number of mixtures in the concentration range 1.0 to 2.5 weight % pentanol in water.

It was confirmed that drop lifetimes can be obtained in the critical heat flux region by comparatively simple techniques and that there is a concentration effect on drop lifetime that is very similar to that observed during critical heat flux boiling studies. A minimum drop lifetime is observed at 1.8 weight % pentanol in water, the same concentration at which maximum critical heat fluxes were obtained in pool boiling studies at one atmosphere by S. J. D. Van Stralen and co‐workers.
Mass transfer from cylinders at various orientations to flowing gas streams
Authors: Willins Richard E. , Griskey Richard G.
Published: March 2009

The effects of angle of cylinder orientation and cylinder length on mass transfer rates were studied for Reynolds numbers ranging from 6,000 to 18,000. Orientations (ϕ) varied from 0° to 90° for cylinders whose L/D's ranged from 5.26 to 21.04.

The relation jm = m(N Re)n fit the data for a given orientation and L/D. Both jm and NNu, data compared favorably to literature values for transverse and parallel flow. Sherwood numbers were shown to be [1] a function of (N Re × sin ϕ) [2] to correlate with Consin's “cosine law” and [3] to be a function of L and ϕ.

Peak mass transfer occurred between 45° and 75°.
Optimum attenuation of inlet fluctuations in a flow system for imperfectly mixed tanks in series
Authors: van Bang Vo , Chiang David , Cholette A.
Published: March 2009

The damping effect of a cascade of identical imperfectly mixed reservoirs on fluctuations in the feed is presented as a function of the various parameters of the flow system.

For a sudden and lasting change in concentration of the feed, the optimum conditions are presented such that the rate of change in the outlet stream be kept to a minimum during the transition period.

In the case of a single square wave disturbance, it is shown how the maximum upset in the outlet stream is related to the characteristics of the system.

The relative performance of various systems is shown graphically, based on the model of partial mixing and short‐circuit for each of the tanks in a cascade.

When little or no channeling is present, the best attenuation for the two cases considered is often obtained by using a cascade of only two reservoirs. As the degree of channeling increases, more reservoirs are required for an optimum performance.
Transesterification of dmt with ethylene glycol catalyzed by amberlyst 15
Authors: Yamanis John , Adelman Maurice
Published: March 2009

The catalytic effects of the macroreticular cation exchange resin Amberlyst 15 (H+) on the transesterification of dimethyl terepbthalate with ethylene glycol have been investigated in a batch reactor and at the temperature of 146°C with the aid of extensive chemical analysis. The resin exhibited significant intraparticle diffusion effects for the disappearance of dimethyl terephthalate and promoted the dehydration and subsequent etherification and polymerization reactions of ethylene glycol to a very significant extent. The side reactions of ethylene glycol rendered the transesterification process in the presence of Amberlyst 15 (H+) inefficient.
The effects of an electrostatic field and air stream on water jet break‐up length
Authors: Garmendia L. A. , Smith I. K.
Published: March 2009

An experimental study of the break‐up length of a circular section liquid jet subject to the combined action of a coaxial airstream and an electrostatic field is reported. A high speed photographic technique has been employed and the results have been correlated empirically by the following dimensionless equation:

where “b” and “k” are functions of Reynolds number.
The behaviour of the dispersed phase in liquid‐liquid cocurrent flow through a packed bed
Authors: Duffy John P. , Kadlec Robert H.
Published: March 2009

The drop size distributions produced by the cocurrent flow of kerosene dispersed in water through a vertical column packed with spheres have been measured at different levels of flow rate, volume fraction dispersed phase, packing diameter and height of packed bed. The drop size measurements were made by isolating and photographing a portion of the dispersion as it emerged from the packing. The Sauter mean diameter is predicted by:

where C is a constant, f(ϕ) is the phase fraction effect, ∈ is the power input per unit volume, τ is the residence time and dp is the packing diameter.
Effect of pretreatment and adsorption conditions on gas adsorption by supported metal catalysts
Authors: Flynn Peter C. , Wanke Sieghard E.
Published: March 2009

The influence of pretreatment and adsorption conditions on the adsorption of oxygen and hydrogen on supported Pt and Rh catalysts has been studied. It has been found that reduction conditions (temperature and time) and subsequent out gassing conditions influence the amount of gas adsorbed. Oxygen and hydrogen uptakes measured in a static system were significantly different than those measured in a dynamic system. Reproducible adsorption uptakes can be obtained by careful control of pretreatment and adsorption conditions.
The mechanism of the adsorption of ethyl xanthate ion on galena (II)
Authors: Wells P. F. , Van Cleave A. B.
Published: March 2009

Studies of the adsorption of 35S labelled ethyl xanthate ion and of 35S labelled diethyl dixanthogen show that both species are competitively chemisorbed to an approximately equal extent on a galena surface, but that ethyl xanthate ion is oxidised to a species which is physically adsorbed, while diethyl dixanthogen is reduced to ethyl xanthate ion which is partially desorbed. It is suggested that galena surfaces are sufficiently heterogenous that oxidative chemisorption and oxidation of ethyl xanthate ion can take place on the anodic parts of the surface while diethyl dixanthogen can be reductively chemisorbed or completely reduced on the cathodic areas.

The relationship of these processes to the normal flotation of galena is discussed.
High temperature propane cracking in an argon plasma with the presence of aluminum vapor and tungsten particles
Authors: Meubus Paul
Published: March 2009

Propane cracking has been carried out in argon, in the presence of either aluminum or tungsten vapor as well as condensed particles of the same metals. The cracking reaction was taking place in the homogeneous phase of a carbon/hydrogen system, yielding mainly acetylene and hydrogen. Propane/argon molar ratios of 1.5 and 6.0% were used, associated with aluminum or tungsten, in concentrations ranging from 0.02 to 0.75%. Maximum acetylene yields up to 93% were obtained in the presence of metal vapor, against a maximum attainable value of around 67% without metal vapor in the plasma. Also, the optimum temperature required for maximum conversion markedly decreased in the presence of metal vapor.

Maximum conversion values occurring around 4,000°K in the presence of aluminum or tungsten, associated with similar crystalline structures related to these metals, lead to the assumption of a solid catalytic effect promoted by condensed metal vapor in the quenching phase. Also, a strong spectroscopic emission at 3,092.7A for aluminum excited atoms could explain the high conversion obtained around 5,000°K when smaller propane/argon ratios are used.
On the dehydrogenation reaction of n‐butane with the deactivation of alumina‐chromia catalyst
Authors: Uchida S. , Osuda S. , Shindo M.
Published: March 2009

An experimental study on the dehydrogenation reaction of n‐butane to n‐butene with alumina‐chromia catalyst has been performed using a differential reactor. N‐butene produced and coke deposit on the catalyst were continuously measured and the mechanisms of the reactions of dehydrogenation of n‐butane and coke deposition have been investigated.

According to the assumptions that there are two types of active sites effective for the dehydrogenation reaction, Lewis acid site and Brönsted acid site, and that the coke deposition takes place only at Lewis acid sites, the rate equations of these reactions have been obtained.
The application of spectral analysis in monitoring extraction column behavior
Authors: Strand Michael J. , Garlid Kermit L.
Published: March 2009

Correlation and spectral functions resulting from the analysis of organic phase volume fraction measurements on a pulsed, sieve‐plate solvent extraction column are presented, and some of the changes that occur as the flow characteristics of the column change are shown. Spectral functions reveal the shifts in operation more directly than do the correlation functions. General trends of both correlation and spectral functions with changing flow characteristics are discussed. Spectral density ratios which reflect the power density in the low frequency bandwidth from 0 to 0.1 Hz relative to that at the pulsing frequency are defined. These ratios are shown to correlate directly with the mode of column operation and are especially sensitive to incipient flooding. Hard limiting of the data prior to spectral analysis is shown to have little detrimental effect on the calculated functions of interest.
Holdup dynamics of a single stage gas‐solid fluidized bed adsorber
Authors: Papadatos K. , Svrcek W. Y. , Bergougnou M. A.
Published: March 2009

The dynamics of the tray solids holdup for a single stage gas‐solid fluidized bed adsorber with a downcomer was studied. The method chosen was based on a material balance of the form \documentclass{article}\pagestyle{empty}\begin{document}$ L_i - L = \frac{{dH}}{{dt}} $\end{document} and an experimental relationship of the holdup H to the solids flowrate L. When the column to weir diameter ratio was 4.4 and 8.8 this relationship was of the linear form H = Hs + τL implying first order dynamics with time constant equal to τ. The time constant was not affected by the superficial gas velocity but it was shown to be a linear function of the weir height. The weir diameter and the particle density of the solids also showed an effect. Specifically, τ increased with the particle density and with decreasing weir diameter. When the column to weir diameter ratio was increased to 13.5 the holdup to solids flowrate relationship was non‐linear.
Non‐foaming adsorptive bubble separation of DBSNa and foam separation of cadmium
Authors: Kubota Katsuyuki
Published: March 2009

In recent years, the use of synthetic surfactants, “detergents”, has brought about extensive foaming on rivers and during sewage treatment. Many methods have already been proposed on the removal of surfactants from waste water by the physico‐chemical approach. The present paper however deals with the removal of the anionic surfactant, dodeclbenzensulfonate (DBSNa, M.W. = 348.48) form aqueous solution by the bubble separation technique, which has already been investigated in model systems by some workers.(1–10) This paper is also devoted in part to the removal of cationic metallic ion(12–17) from its dilute solution by suing a DBSNa collector in a stable foaming region, (pH = 6.3) similar treatments have employed the precipitate floatation mehtods.(18,19)
The influence of viscous interaction on the diffusional deposition of particles
Authors: Dahneke Barton
Published: March 2009

Viscous interaction may prevent or retard diffusional deposition of fluid‐borne particles and droplets onto a collecting surface. The possible importance of viscous interaction has been recognized in the literature(1–3), but quantitative results which demonstrate the importance of viscous interaction are scant. Rather, the scant reported evidence is confusing. This paper reports the results of a theoretical investigation of the influence of viscous interaction on diffusional deposition of particles. The results show negligible influence in gaseous media, but sometimes significant retardation in liquid media, especially if electrical double layers also retard deposition.
Fluid flow pattern, minimum spouting velocity and pressure drop in spouted beds
Authors: Grbavčíc Ž. B. , Vukovíc D. V. , Zdanski F. K. , Littman H.
Published: March 2009

This study extends the theory of Mamuro and Hattori to beds of less than the maximum spoutable height. The new model gives predictions for the fluid flow pattern, minimum spouting velocity and spouting pressure drop which are in agreement both with experimental data on beds spouted with air and water (obtained in this study) and with literature data.

A correlation for Hm in water spouted beds of spherical glass particles is also presented.
Frequency response of liquid fluidized systems. Part II Effect of liquid viscosity
Authors: Mehta S. C. , Shemilt L. W.
Published: March 2009

The imperfect pulse response technique, employing two measurement points, has been applied to the characterization of fluid mixing in systems where 0.5 mm glass beads are fluidized by liquids of viscosity (0.56 to 7.74 cp.) for bed porosities from 0.45 to 0.95. The frequency content of the input pulses was kept relatively high by experimenetal techniques. Frequency responses were determined from the measured residence time distributions. Axial dispersion coefficients for the axial dispersed plug flow (ADPF) model were calculated by moments and by frequency domain analysis, with considerable discrepancies at high degrees of mixing. Parameters for a time‐delay timedelay time‐constant (TDTC) model have also been estimated. A correlation for the significant time‐delay parameter has been developed for the range of viscosities and porosities. While both models can reasonably predict the frequency response, the TDTC model shows somewhat lower deviations and has the major advantage of predictable parameters through the correlation presented.
Adsorption of binary liquid‐phase hydrocarbon mixtures on arctic terrain
Authors: Moore J. P. , Phillips C. R. , Tombalakian A. S.
Published: March 2009

Adsorption isotherms for the sorption of various binary liquid‐phase hydrocarbon mixtures on Arctic terrain were determined. The terrain was classified into three distinct layers, moss, detritus, and clay. The sequence of mass loading (g of hydrocarbon adsorbed/g of terrain) for each layer, and hence for the total terrain, was found to be the same, that is, nC16 > n‐C10 > p‐xylene > benzene > n‐C5, determined from liquid phase adsorption from binary systems in which n‐C10 was one component The behaviour of the Arctic terrain in the binary hydrocarbon mixtures investigated could be described by Freundlich adsorption isotherms. The extent of adsorption increases with the organic content of the terrain, and factors which determined adsorption appear to be physical in nature. For the hydrocarbons studied, the higher molecular weight hydrocarbon was ferentially adsorbed.
Axial dispersion in a reciprocating plate extraction column
Authors: Kim S. D. , Baird M. H. I.
Published: March 2009

Axial dispersion coefficients have been measured in the continuous phase of a 5 cm diameter reciprocating plate extraction column. The measurements were made by observing the course of an instantaneous chemical reaction between acid and base in the continuous phase, using phenolphthalein as indicator. The data for single‐phase operation have been correlated in terms of amplitude and frequency of reciprocation, and spacing between plates. A similar correlation applies for liquid‐liquid operation under intense agitation. At low agitation rates, and for gas‐liquid operation, the dispersion coefficient depends strongly on the flow rate of dispersed phase.
Hydrogenolysis of propane on supported ruthenium. Effect of pressure
Authors: Anderson Robert B. , Tsjeng Po K.
Published: March 2009

The hydrogenolysis of propane on ruthenium‐on‐alumina was studied at 112° to 150° and 1.1 to 7.1 atm. abs. in a Carberry reactor. The simple power rate equation, that is usually employed for hydrogenolysis, was found to lack the proper mathematical form for representing the present data. Although the equation was adequate for fitting results at a given pressure, it failed to fit data taken at several pressures. The rate decreased with operating pressure to the −2.3 power, but the power equation predicted pressure exponents of −1. to −1.5. Therefore, a number of more complicated rate equations was tried. An acceptable equation involved a 2‐site mechanism for reaction of a dissociatively chemisorbed C3 species with appreciable coverages of the metal surface by dissociatively chemisorbed hydrogen and physically adsorbed propane.

Ethane produced in the initial reaction of propane splits about 1% as fast as propane, and as pressure is increased, splitting of ethane decreases more rapidly than the hydrogenolysis of propane. Selectivity equations indicate that the rate of dissociative chemisorption of ethane is about 2% of that of propane, and that this factor largely determines the rates of hydrogenolysis of ethane and propane.
The analysis of data from recirculation reactors
Authors: Boag I. F. , Bacon D. W. , Downie J.
Published: March 2009

A critical assessment is made of a commonly used procedure for estimating the kinetic parameters in a catalytic rate model using data obtained in a recirculation reactor. Serious deficiencies in this procedure are identified, and an alternative estimation scheme is proposed.

The component mass balance equations in a recirculation reactor involve no differentiation or integration, and therefore the estimation of kinetic parameters appears to be simpler than the corresponding task with integral reactor data. However, a detailed examination shows that this is not the case, and that the effort involved in correctly estimating the parameters and their covariance matrix may not be significantly different for the two reactor types. Data obtained by Boag et al(10) from the vanadia‐catalysed gas‐phase oxidation of o‐xyleue in a recirculation reactor are used to demonstrate the differences between the parameter estimation procedure in common use and the procedure recommended in this paper.
Mass transfer from crystalline surfaces in a turbulent impinging jet. part 2: Erosion and diffusional transfer
Authors: Giralt Francesc , Trass Olev
Published: March 2009

Simultaneous erosion and diffusional transfer from transcinnamic acid coatings in submerged, axisymmetric, impinging jets of water has been studied at a Reynolds number of 100,000 and a nozzle height of 8 diameters. The concentration driving force was varied from zero to the acid solubility value. For low transfer rates roughness development was small and the two transfer modes were additive. At higher dissolution rates, however, diffusion enhanced erosion by loosening surface grains. This loosening action was largest in the impingement region where large surface roughness developed and further enhanced the high dissolution rates and subsequent interactions.
Mass transfer in a ternary liquid‐liquid system
Authors: Cullinan Harry T. , Ram S. K.
Published: March 2009

Isothermal mass transfer is studied in the partially miscible system, acetone‐glycerol‐water, using a modified stirred extraction cell of the Lewis type. Mass transfer rates between an unsaturated light phase and an effectively saturated heavy phase are determined. From such data, the partial mass transfer coefficients in the light phase can be calculated. The results confirm that, during such ternary extraction processes, the rate of mass transfer of a given constituent can depend appreciably on the driving forces of the other diffusing species.
Alumina trihydrate crystallization. Part 2. A model of agglomeration
Authors: Halfon A. , Kaliaguine S.
Published: March 2009

In the second part of this paper on the kinetics of crystallization of aluminum trihydroxide from caustic aluminate solutions, interest is specially focused on the analysis of crystal size distribution as a function of time, in an isothermal batch crystallizer.

Breakdown and agglomeration are shown to affect these curves simultaneously. While only qualitative information on breakdown was obtained, agglomeration could be isolated experimentally. Its rate was measured and fitted to a kinetic model which pictures agglomeration as the result of binary collisions between particles.
Research on valve trays. Hydraulic performance in the air‐water system
Authors: Piqueur H. , Verhoeye L.
Published: March 2009

The entrainment and the pressure drop were studied in a 30 cm distillation column with three valve trays. Three industrial types of valves were investigated using an air‐water system. The air rate varied from 100 m3/h to 800 m3/h and the liquid rate from 100 1/h to 1.000 1/h.

Four weir heights (4.5, 6.0, 7.5, 9.0 cm) and four plate spacings (30, 37.5, 42.5, 50 cm) were used.

Equations for the amount of entrainment and the pressure drop were derived and compared to previous results from the literature.
Charged membrane ultrafiltration of heavy metal salts: Application to metal recovery and water reuse
Authors: Bhattacharyya Dibakar , Schaaf David P. , Grieves Robert B.
Published: March 2009

An experimental investigation is presented of the thin‐channel ultrafiltration of 0.6 × 10−3 M to 15.0 × 10−3 M aqueous solutions of Cu2+, Ni2+, or Zn2+ sulfate or chloride salts through a negatively‐charged, non‐cellulosic membrane. Multi‐salt solutions and the actual rinse water from a Watts‐type‐nickel‐plating process are also ultrafiltered. The membrane provides a Ni2+ rejection of 0.83 and water flux of 1.0 × 103 cm/sec (23 gal/ft2 day) at a transmembrane pressure difference of 4.0 × 105 N/m2 (3.9 atm). The membrane rejection and water flux data are utilized in a computer simulation procedure for scale‐up to a multi‐module, two‐staged process for the closed‐loop operation of a plating plant.
Wet oxidation of active carbon
Authors: Charest F. , Chornet E.
Published: March 2009

As a preliminary step to studies on the regeneration of active carbon, its wet oxidation has been followed in order to obtain information about the different parameters involved: agitation, temperature and pressure.

The oxidation reaction takes place in the liquid phase and it does not proceed at significant rates below 200°C, even with high initial oxygen pressures. The oxidation proceeds rapidly beyond 275°C at pressures as low as 30 atm. The only detectable reaction product is carbon dioxide.

Although mass transfer effects are minimized at stirring speeds higher than 400 rpm, a visible abrasion of the carbon was apparent beyond 300 rpm. Consequently, the study was carried out at around 200 rpm. Mass transfer effects had to he considered then. Estimation of the different transfer coefficients was done from the experiments and through existing correlations. In this way the kinetics could be obtained. The rate of reaction can be represented by a first order kinetic expression.

Comparison of the rates has been done at fixed conversions. The intrinsic rate constant has a surprisingly low activation energy of 8.4 Kcal/mole suggesting that the oxidation reaction proceeds via a free radical mechanism. The overall rates show a maximum at conversions varying between 0.10 and 0.40. The specific surface area decreases regularly with reaction time, indicating that the reaction takes place throughout the particle.
An experimental technique for determining the significance of intraparticle diffusion in an aging catalyst
Authors: Best Donald A. , Wojciechowski Bohdan W.
Published: March 2009

The effects of simultaneous decay and diffusion on a first order reactiion have been investigated. Two limiting types of behaviour are observed. In the first, cumulative conversion on diffusion limited catalysts is shown to behave in a manner opposite to that expected if the catalyst were non‐aging, in that conversion decreases with decreasing particle size. The other extreme shows behaviour consistent with that observed on a non‐decaying catalyst; that is, conversion increases with decreasing catalyst size. Experimental evidence for such behaviour is observed with cumene cracking and gas oil cracking, both on zeolite catalysts.

As a consequence of the above observations, it is proposed that a new test involving experimentation at constant cat/oil ratio and over a range of space velocities be used to determine the significance of intraparticle diffusion on a catalyst subject to decay.
Transient behaviour of a non‐ideal tubular reactor
Authors: Nigam K. D. P. , Vasudeva K.
Published: March 2009

Experimental data are reported for the unsteady state behaviour of a laminar flow reactor with first order homogeneous liquid phase reaction. The data are in agreement with the predictions of the dispersion model, using previously reported reaction‐dependent dispersion coefficients which directly gives the bulk mean concentration. The use of proper boundary conditions, ignored in a recent paper on this topic(19), is found to significantly influence the predictions. Unlike the conclusion drawn in(19) it is shown that the Taylor model is unable to correctly predict the reactor length for fast reactions even for high conversions.
The measurement and prediction of the solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution
Authors: Lee J. I. , Otto F. D. , Mather A. E.
Published: March 2009

The solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution has been determined at temperatures of 40°C and 100°C. Partial pressures of CO2 ranged from 0.7 to 5630 kPa, while partial pressures of H2S ranged from 0.7 to 3780 kPa. The present results extend the published data on this system which were limited to partial pressures below 200 kPa. The results have been compared with two methods of prediction based upon a thermodynamic model.
Flow patterns and mass transfer rates in fluidized bed ion exchange equipment
Authors: Slater M.J. , Lucas B. H.
Published: March 2009

The axial mixing of ion exchange resin and liquid in fluidized beds is modelled by a series of well‐mixed cells for the resin and an equal or larger number of mixed cells for the liquid. Concentration breakthrough curves are calculated using this mixing model, assuming finite mass transfer kinetics and irreversible equilibrium. The model is used to describe mixing patterns and kinetics in static fluidized beds (no resin flow); the information so obtained can be used to design continuous and periodic flow counter‐current fluidized bed ion exchange systems.
The effects of surface viscosity on the axisymmetric drainage of planar liquid films
Authors: Barber A. D. , Hartland S.
Published: March 2009

The Reynolds equation is extended to allow for the effects of shear and dilational surface viscosities on the axisymmetric drainage of planar films. It is shown that the number of immobile surfaces, n, may be expected to decrease with increasing film radius and bulk viscosity and with decreasing film thickness and surface viscosity, as observed experimentally. The predicted rate of film thinning agrees well with available experimental results.
Thermal energy storage in inorganic salts
Authors: Verma Arun , Johnson Keith E. , Sherman E. O.
Published: March 2009

The work involved studying the potential of Na2SO4, NaCl, KCl, CaCl2 and some eutectic mixtures of inorganic salt for storing thermal energy. Heat storage materials have wide application in devices such as “off‐peak” space heating furnaces. Data reveal Na2SO4 to be a better heat storage material than other salts as well as conventional heat storage materials because of its dimorphic nature and high heat of transition. It is estimated that less than 0.29 m3 of Na2SO4 would be required for heating a normal sized house on the Canadian Prairies.
Kinetics of o‐Xylene oxidation over sintered vanadium pentoxide in a spinning catalyst basket reactor
Authors: Pant Gopinath S. , Chanda Manas
Published: March 2009

Kinetics of vapor phase oxidation of o‐xylene has been studied over sintered and compacted vanadium pentoxide in a continuous stirred tank catalytic reactor in the temperature range of 450–517°C at atmospheric pressure. The major product obtained is phthalic anhydride. The other products are maleic anhydride and carbon dioxide.

The reaction rate data are well represented (with average absolute deviation less than 6%) by the following expression derived by applying the steady‐state oxidation‐reduction model of Mars and van Krevelen to a parallel reaction scheme and assuming first order with respect to both o‐xylene and oxygen:

Significantly, the activation energies for all three postulated reactions with rate constants k1, k2, and k3 turn out to be identical having a value of 14.8 kcal/mole, which may be taken to imply that there is only one rate‐influencing reaction step for all the products and not three as assumed in deriving this equation.
Phase equilibria for the system propane‐ethane‐carbon dioxide
Authors: Hamam Salah E. M. , Lu Benjamin C. Y.
Published: March 2009

Vapor‐liquid equilibrium data for the ternary system propane‐ethane‐carbon dioxide were determined experimentally at 244.3 and 266.5 K by means of a forced recirculation apparatus. The total pressure investigated varied from 87.5 to 433 psia. The data obtained were compared favourably with the values predicted by means of the Redlich‐Kwong equation of state with a modified procedure. The average absolute deviation between the experimental and calculated P is less than 3% and in y less than 0.0140 mole fraction.
Estimation of standard heats of formation ΔH, standard entropies of formation ΔS, standard free energies of formation ΔF and absolute entropies S of hydrocarbons from group contributions: An accurate approach
Authors: Thinh Tran Phuc , Trong Truong Khac
Published: March 2009

A group contribution method for calculation of standard heats of formation ΔH*fT, standard entropies of formation ΔS*fT standard free energies of formation ΔF*fT and absolute entropies S*T, of hydrocarbons is proposed. It is shown that this method is more accurate than any of the ones now appearing in the literature.
Consolidation of sand formation using freon'll gas hydrate
Authors: Cheng W. K. , Pinder K. L.
Published: March 2009

Freon 11 gas hydrate was used to block the pores of four size ranges of sand from 24 mesh to 60 mesh. A 50.8 mm deep bed of sand when thus “frozen” with hydrate could sustain a dfferential water pressure of at least 6895 kPa.

A subcooling of about 5 to 6°C below its thermodynamic formation temperature was required to cause the hydrate to form such a plug. Once formed, the hydrate remained stable at temperatures up to its decomposition temperature.

The time required for the hydrate crystal to grow to a size large enough to block the pores of the bed was about two hours. The amount of hydrate forming agent required to block the sand pores was found to be approximately that calculated from the ideal composition of the hydrate.
Caractéristiques rhéologiques des suspensions de tourbe
Authors: Mejean L. , Boulos M. I.
Published: March 2009

L'écoulement des suspensions de tourbe dans l'eau a été étudié sur un domaine de concentrations compris entre 0.75 et 2.25% en poids sec. La granulométrie des fibres était inférieure à 3 mesh.

Les pertes de charge ont été mesurées sur une plage étendue de débits, le nombre de Reynolds variant entre 103 et 105, dans trois tubes horizontaux de diamètre interne respectif 50.8, 38.1 et 25.4 mm.

Les résultats indiquent que la déviation au comportement newtonien augmente avec la concentration et le diamètre des conduites. La comparaison avec des suspensions diluées de pǎtes à papier révèle que le comportement de ces deux types de suspensions présente les měmes particularités. Les suspensions de fibres sont des fluides non homogènes, et les modèles rhéologiques classiques ne peuvent décrire leur comportement. Le modèle de l'anneau périphérique, qui suppose, en écoulement laminaire, la présence d'un réseau enchevětré de fibres, explique les résultats expérimentaux obtenus.

L'analyse granulométrique des particules met en évidence que le type de pompe utilisé a un effet sur la dégradation des fibres.
The coalescence of H2S and CO2 bubbles in water
Authors: Sagert Norman H. , Quinn Michael J.
Published: March 2009

Coalescence times are reported for bubbles of H2S and CO2 formed on adjacent nozzles in water. With CO2, times were small (1–3 ms) at pressures below 2 MPa, and rose to 20 ms at 3.4 MPa. With H2S, the logarithm of the coalescence time was proportional to pressure, and coalescence times reached 100 ms at 1.7 MPa. Film stretching rates were calculated assuming that the film surfaces were slightly immobile. By using a form of Vrij's theory for the inherent breaking time of films of constant thickness, the effective number of immobile layers could be calculated. Since these were in the range 10−2 to 10−3, only a small amount of “stiffness” in the film surface is enough to cause large changes in coalescence time.
Effect of heater diameter on the critical heat flux from horizontal cylinders in pool boiling
Authors: Rao P. K. Mohan , Andrews D. G.
Published: March 2009

The characteristic variation of critical heat flux (CHF) with heater diameter in the pool‐boiling of horizontal cylinders is discussed. Critical heat flux expressions have been obtained based on hydrodynamic considerations for saturated pool‐boiling of cylinders and are compared with existing and new data. Experimental studies are reported which verify the postulated mechanics of the boiling process at CHF over a range of cylinder diameters.
Technology and economics of coal gasification
Authors: Papic M. M.
Published: March 2009

The best known commercial coal gasification processes which use oxygen (air) and steam as gasifying media are the gas producer process (normal pressure, fixed bed), Lurgi process (high pressure, fixed bed), Winkler process (normal pressure, fluidized bed) and Koppers‐Tetzek process (normal pressure, entrained). Fixed bed and fluidized bed processes are suitable for gasification of noncaking and weakly caking coals with high ash fusion temperatures (> 1200°C). The entrained system is suitable for gasification of any coal.

Low‐caloric gas (∼ 150 Btu/scf) can be produced by the gas producer, Lurgi and Kinkier processes; medium‐ (∼ 300 Btu/scf) and high‐caloric (∼ 950 Btu/scf) gas by any process. Lurgi and Koppers‐Totzek processes are preferred processes for production of synthesis gas at the present time.

The costs (/Btu) of production of low‐caloric gas are the lowest followed by the medium‐ and high‐caloric gas costs (see Figure 6). The costs of gas production from coal are mainly dependent on the efficiency of the gasification process, scale of operation and the cost of fuel.
Détermination du facteur d'efficacité et du coefficient de tortuosité d'un catalyseur au vanadium pour l'oxydation du dioxyde de soufre
Authors: Herce J. L. , Gros J. B. , Bugarel R.
Published: March 2009

Les anteurs présentent les résultats cinétiques obtenus lors de l'oxydation de SO2 à la pression atmosphérique sur un catalyseur à base de vanadium pour des grains de catalyseurs d'un diamètre de 0,04–0,05 cm, 0,0115–0,02 cm, 0,15–0,16 cm, 0,2–0,21 cm et 0,3 cm. La gamine de température varie de 500 à 630°C. A partir de la comparaison de l'efficacité des grains et d'un modèle de calcul de cette efficacité, ils en déduisent la diffusion effective de SO2 dans le grain et le facteur de tortuosité du catalyseur. Ces valeurs sont comparées avec celles obtenues par Kadlec et col. et Livbjerg et col.
Evaluation of capital cost data: Heat exchangers
Authors: Woods Donald R. , Anderson Susan J. , Norman Suzanne L.
Published: March 2009

Capital cost correlations are given for heat exchangers and furnaces. Correlations available in the literature and current data are compared on a consistent basis. Forty‐six graphs show the relative magnitude of the different correlations and the recommended correlation for each type of equipment is summarized in a table. Some data on the costs of installing heat exchange equipment are given.
Turbulent flow in helically ribbed pipes
Authors: Shook C. A. , Sagar S. K.
Published: March 2009

Velocity profiles, turbulence intensities and Reynolds stresses were determined in pipes containing three helical ribs equally spaced on the pipe wall. Pitch to diameter ratios of 8 and 11 were used. The fluid considered was air and measurements were made with X wire probes calibrated for pitch and yaw effects.

The ribs appeared to affect the axial flow via the tangential component which reached a maximum below the ribs in most cases. Evidence of increases in mixing length near the wall and decreases in the central core was obtained. These are in agreement with recent theoretical predictions of other workers. Turbulence intensities were not significantly altered when normalized with the usual friction velocity.
Characterisation of inelastic poweriaw fluids using falling sphere data
Authors: Uhlherr P. H. T. , Le T. N. , Tiu C.
Published: March 2009

Two simple methods are presented for the characterization of inelastic power law fluids from falling sphere data. The methods involve the application of shear rate or shear stress correction factors which have been derived theoretically using Slattery's solution for creeping flow about spheres. Flow curves obtained using these methods are in excellent agreement with those measured on a Weissenberg rheogoniometer for 0.83 > n > 1.0.

The experimentally determined drag coefficients are found to be in good agreement with the predictions of Slattery's creeping flow first approximation solution.

The wall correction factors of Faxen and Francis appear to be valid for inelastic non‐Newtonian fluids up to a diameter ratio of at least 0.08.
Viscous effect on stagnation depth of bubbles in a vertically oscillating liquid column
Authors: Marmur Abraham , Rubin Eliezer
Published: March 2009

Previous theories which evaluated the stagnation depth of bubbles in a vertically oscillating liquid column are reviewed, and it is pointed out that they used an insufficient criterion for determining stagnation. The correct condition, which states that stagnation means zero mean velocity rather than acceleration, necessitates the solution of the equation of motion of the bubble, and thus viscous drag has to be included. It is shown, in accordance with available experimental data, that the value of the dimensionless group M = ω4A2ρ/2gPo (which gives the stagnation depth h) is not in general a constant, but is dependent on four other dimensionless groups. Although there is no reliable information concerning the drag coefficient curve for such a situation, it is suggested, on the basis of comparison between different drag coefficient curves, that the high values of M reported in the literature and not accounted for by theory are due to bubble shape deviations from sphericity in viscous flow.
An experimental study of convective instability in the thermal entrance region of a horizontal parallel‐plate channel heated from below
Authors: Hwang G. J. , Liu Cheng‐Liung
Published: March 2009

This paper presents results of an experimental investigation on the onset of longitudinal columnar vortices due to buoyant forces in the thermal entrance region of a horizontal parallel‐plate channel heated from below. Channels with width 30 cm and heights h = 2, 3 and 4.5 cm were employed in the experiment. The instability of the convective motion is caused by the effects of temperature gradients in both longitudinal and vertical directions and was observed by a direct flow‐visualization technique using smoke. Photographs of the front and top views of the vortex rolls are presented. Experimental results indicate that the wave number of vortex rolls remains constant along the flow direction and tends to approach the theoretical value as the channel width‐height ratio increases. It was also observed that the critical Rayleigh number from flow visualization is 1.4 to 10 times higher than the critical value from linear theory.
Gas‐liquid mass transfer coefficients for cocurrent upflow in packed beds — effect of packing shape at low flow rates
Authors: Alexander B. F. , Shah Y. T.
Published: March 2009

Gas‐liquid mass transfer coefficients were determined by oxygen desorption for cocurrent upflow in packed beds. Data are included for seven different catalyst supports, four of which have not appeared previously in the literature. Very low flow rates (liquid: 0.9–6.0 mm/s, gas; 1.5–31 mm/s) of interest in pilot‐scale catalytic hydrogenation, were investigated. The results correlated well with liquid and gas flow rates for each packing. In addition, the data for all packings were correlated reasonably well by the energy dissipated in the liquid phase.
Mass transfer characteristics of horizontal agitated contactors
Authors: Joshi J. B. , Sharma M. M.
Published: March 2009

The values of effective interfacial area, a, and liquid side mass transfer coefficient, kLa, were obtained in 0.385, 0.57 and 1.0 m i.d. horizontal agitated contactors by using chemical methods. Propeller type of impellers were employed for agitation. Two modes of operation were studied: (i) surface aeration and (ii) sparging of gas. The impeller speed was varied from 50 to 700 rev/min, and the nozzle gas velocity was varied from 40 to 160 m/s. The effects of impeller spacing, liquid submergence and nozzle gas velocity on the values of a and kLa were investigated. A scale‐up criterion is discussed.
Kinetics of the liquid phase reaction between carbon dioxide and diethanolamine
Authors: Coldrey P. W. , Harris I. J.
Published: March 2009

The kinetics of the reaction between carbon dioxide in aqueous solution and aqueous diethanolamine have been studied using the thermal flow method. The data indicate that the kinetics of the reaction is complex. The particular mechanism proposed consists of two reactions which initially compete for the available carbon dioxide. One of these reactions is reversible, and regenerates carbon dioxide as the overall reaction proceeds. The species participating in the proposed reversible reaction were not identifiable from the data obtained.
Kinetics of hydrogen reduction of cobalt sulfide
Authors: Fahim M. A. , Ford J. D.
Published: March 2009

The hydrogen reduction of cobalt sulfide (Co9S8) at atmospheric pressure in the temperature range 600–800°C has been experimentally investigated. When sulfide pellets were used, the rate constants were overestimated. The true intrinsic kinetics of this reaction were obtained from another set of experiments using sulfide powder, under conditions such that the topochemical shrinking core model in the chemical control regime could be applied. In the temperature range 600–737°C, the rate constant for the powder reaction could be expressed as:

k = 15,600 exp (–27,800/RT)

Above 780°C, cobalt metal whiskers were formed, and this led to swelling and cracking of pellets.
pH control of a continuous precipitator
Authors: Attarian C. , Baker C. G. J. , Svrcek W. Y.
Published: March 2009

The size distribution of precipitates formed in a double decomposition reaction has been found previously to be highly sensitive to pH. Consequently, automatic control of pH is necessary to maintain a constant product size distribution. In the present study, steady‐state, dynamic, and pH control tests were performed on a continuous precipitator in which calcium carbonate was produced. Agreement between the experimental dynamic response and that predicted by a model based on equilibrium and stoichiometry was poor. However, satisfactory feedback control of the pH was achieved using proportional plus integral action. Simultaneous measurements of the precipitate size distribution using a Coulter Counter demonstrated that this resulted in good conrol of the mean paricle size.