bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat transfer from finned surfaces with a uniform fouling deposit
Authors: Middis J. , Möuller‐Steinhagen H. M.
Published: March 2009

The change in thermal efficiency when a uniform fouling deposit is added to an extended surface was determined by two‐dimensional numerical analysis. Calculations were done over a wide range of parameters such as fin length, fin thermal conductivity and deposit thermal conductivity. The results were compared with two previously reported analytical models, namely, a Series Model and a Parallel Model. Owing to simplifications used in the models, major discrepancies exist between the analytical and the numerical results for most relevant situations, especially in the case of the Parallel Model.
Distribution of volatile sulphur containing products during fixed bed pyrolysis and gasification of coals
Authors: Furimsky Edward , Palmer Allan D. , Cheng Meng
Published: March 2009

Three sub‐bituminous and two bituminous coals from Western Canada were used to study the evolution of H2S, COS and SO2 during the pyrolysis and gasification processes in a fixed bed reactor. For all types of coals, most of H2S and SO2 were released during the devolatilization stage. COS was formed only during the gasification stage in the presence of CO2. The mineral matter of coal may have played a role during the gasification stage. Some observations made during this latter stage in CO2 and/or steam were interpreted in terms of the equilibrium effects.
An inverted cup reciprocating plate for gas absorption
Authors: Baird M. H. I. , Rama Rao N. V.
Published: March 2009

The characteristics of a novel type of reciprocating plate have been investigated. The plate is in the form of an inverted cup, 13.8 cm outside diameter and 7 cm deep, reciprocated on a central shaft in a 15 cm internal diameter water‐filled column. Reciprocation stroke length was 2.9 cm and the frequency was in the range 0–4.5 Hz. Air or oxygen is supplied steadily to the space beneath the cup and escapes from 1 mm diameter holes drilled around the side of the cup. At high reciprocation frequencies, this arrangement produces very fine gas bubbles of less than 1 mm diameter. Measurements have been made of Sauter mean bubble diameter, gas holdup and volumetric mass transfer coefficient for the oxygen‐water system.
An analysis of solid phase formation in a liquid via image processing
Authors: Gu Z. H. , Fahidy T. Z.
Published: March 2009

The kinetics of the formation and propagation of a precipitate phase generated by anodic dissolution is investigated by means of digital image processing of video‐taped laser light reflection. The enhancing effect of externally imposed magnetic fields is also demonstrated.
Correlation and prediction of the viscosity of defined and undefined hydrocarbon liquids
Authors: Allan Juliet Mcclatchey , Teja Amyn S.
Published: March 2009

A new method based on the effective carbon number is presented for the correlation and prediction of the viscosity of liquid hydrocarbons and hydrocarbon mixtures. It is proposed that the effective carbon number for the substance of interest be obtained from a single viscosity datum in the liquid range. The viscosity‐temperature relationships of sixty‐nine hydrocarbons, eleven defined hydrocarbon mixtures and eight crude oil fractions were studied in the present work. In general, calculated viscosities compared favorably with experimental data for all the systems studied. The calculated viscosities were also found to compare favorably with the results of the widely‐used TRAPP method.
A new four‐parameter cubic equation of state for fluids
Authors: Jan Dong‐Syau , Tsai Fuan‐Nan
Published: March 2009

A simple cubic equation of state of the van der Waals type has been developed and successfully applied to both nonpolar and polar fluids. It contains four parameters and only one parameter is temperature‐dependent. The parameters have been determined by using reliable data of vapour pressure and saturated liquid volume, and correlated in terms of critical properties and acentric factor. The P‐V‐T relationships, vapour pressures, volumes, and enthalpies of vapourization were calculated for a variety of substances. Comparison of the calculated results with experimental data and with results obtained from other equations shows that the proposed equation is a superior one in overall performance.
Upgrading of tall oil to fuels and chemicals over HZSM‐5 catalyst using various diluents
Authors: Sharma R. K. , Bakhshi N. N.
Published: March 2009

The upgrading of crude tall oil (CTO) to fuels and chemicals was studied at atmospheric pressure and in the temperature range 370 to 440°C in a fixed bed microreactor containing HZSM‐5. The oil was co‐fed with diluents such as tetralin, methanol and steam. High oil conversions of the order of 80–90 wt. % were obtained using tetralin and methanol as diluents but with steam the conversion only ranged between 36 to 70 wt. %. The maximum concentration of gasoline range aromatic hydrocarbons in the liquid product was 52 and 57 wt. % with tetralin and steam but only 39 wt. % with methanol. The amount of gas product in most of the runs was 1–4 wt.%. A reaction scheme is postulated based on the results.
Catalyst decay in the presence of chain processes in catalytic cracking
Authors: Rice N. M. , Wojciechowski B. W.
Published: March 2009

The Chemical events involved in cracking and catalyst decay are examined in order to ascertain the possible course of catalyst decay. We find that, regardless of whether site activity is lost by “sudden death” or by gradual “inhibition”, the time course of catalyst decay under a wide variety of assumptions is described by the function ā(t) = (1 + Gt)–N′. Under certain conditions, however, sites on their way to complete deactivation may undergo reactivation by the desorption of an inhibiting species. In such cases, our models predict the existence of a lower activity condition which can be time invariant or, after being established by an initial rapid decay, the intermediate less‐active condition evolves to a final, inactive state. Furthermore, if some of the intermediate steps on the way to complete deactivation lead to site activities higher than those of the pristine sites, a sigmoidal curve of conversion versus time on stream can result.
Regeneration of spent activated carbon by wet air oxidation
Authors: Mvndale V. D. , Joglekar H. S. , Kalam Abul , Joshi J. B.
Published: March 2009

The regeneration of activated carbon was studied using the wet air oxidation process in the temperature range of 150–240°C and oxygen partial pressure range of 0.2 to 1.0 MPa. Phenol was used as substrate. The overall mechanism of regeneration has been analysed and the different steps taking place during the regeneration process were individually investigated. Kinetics of oxidation of phenol and oxygen mass transfer coefficients have been estimated in the ranges of temperature and pressure studied. Oxidative degeneration characteristics of activated carbon were also studied. The conditions of temperature and pressure have been found at which the extent of regeneration is favourable.
The effect of electric field on droplet formation and motion in a viscous liquid
Authors: He W. , Baird M. H. I. , Chang J. S.
Published: March 2009

The formation and initial motion of distilled water droplets injected into a viscous oil were studied in the absence of an electrical field and under the influence of a high voltage (up to 10 kV) field. The droplets were formed at a stainless steel nozzle in a rectangular cell (38 × 10 × 10 cm) equipped with grounded parallel plate electrodes along two sides of the cell.

As the voltage applied to the nozzle was increased, the formed droplets were reduced in size and showed repulsion and some upwards scattering; the droplet velocity near the nozzle was greatly increased by the field, with the droplets decelerating as they moved away from the nozzle.

Droplet formation and motion with and without electric field have been compared with predictive models, showing qualitative agreement and partial quantitative agreement.
Correlation of high‐pressure phase equilibria in the retrograde region with three common equations of state
Authors: Dohrn Ralf , K¨︁nstler Wolfgang , Prausnitz John M.
Published: March 2009

Phase equilibria in the retrograde regions were calculated for the methane — n‐decane binary system and for a realistic natural‐gas system (methane ‐ Kensol‐16). Calculations were performed using three equations of state (EOS): Peng‐Robinson, Redlich‐Kwong‐Soave and Perturbed‐Hard‐Chain; calculations were compared to experiment. Liquid‐drop‐out curves and pressure‐temperature diagrams were calculated between 301 and 369 K and pressures to 90 MPa. The binary system was represented best by the Peng‐Robinson EOS. For the natural‐gas system, the Perturbed‐Hard Chain equation yielded the best results, although all equations of state showed appreciable deviations. Good results could only be obtained when binary coefficients were fitted to the experimental retrograde data.
Reduction of coal‐water mixture consistency with soda ash and lime
Authors: Sadler Leon Y. , Sim Kian G.
Published: March 2009

The addition of soda ash and lime to improve the Theological properties of a 60 wt % bituminous coal‐water mixture (CWM) was investigated. Soda ash and lime were used to precipitate calcium and magnesium cations naturally present in the aqueous phase of the CWM. Addition of the required amounts of soda ash and lime alone, based on analyses of the total Ca2+ and Mg2+ burdens in the CWM, using standard water softening technology as well as addition of soda ash and lime along with an ionic dispersant were studied. Significant reduction in consistency was measured following soda ash and lime addition alone, and marked reduction in consistency resulted when both soda ash and lime and dispersant were used. Additive costs to obtain a given degree of consistency reduction were lowered by factors ranging from 3 to 15 with soda ash and lime, either alone or in concert with an anionic dispersant, relative to the use of anionic dispersant alone.
Characteristic mixing length in bubble columns
Authors: Kawase Y. , Tokunaga M.
Published: March 2009

Liquid‐phase mixing in bubble columns is discussed on the basis of the mixing length theory. A characteristic mixing length defined as a lumped hydrodynamic parameter is estimated. The results indicate that the characteristic mixing length assumed previously by one of the authors is reasonable.
Flow of power law liquids through particle assemblages at intermediate reynolds numbers
Authors: Jaiswal A. K. , Sundararajan T. , Chhabra R. P.
Published: March 2009

The complete equations of motion and continuity have been solved numerically using the finite element method for the flow of power law liquids through assemblages of rigid spherical particles. The inter‐particle interactions have been simulated using the free surface cell model. Extensive results on drag coefficients have been obtained under a wide range of physical and operating conditions (0.9999 ≥ 0.3), 1 ≥ n ≥ 0.4 and 20 ≥ Re ≥ 1. The observed dependence of drag coefficient on voidage and non‐Newtonian flow behaviour index have been explained qualitatively with the aid of order of magnitude considerations. Finally, the theoretical predictions have been validated using suitable experimental data available in the literature.
Flow structure of the dispersed gasphase in real multiphase chemical reactors investigated by a new ultrasound–doppler technique
Authors: Bröring S. , Fischer J. , Korte T. , Sollinger S. , Lübbert A.
Published: March 2009

The flow structure of the dispersed gas phase within an aerated stirred tank reactor of pilot scale (600L) has been investigated by means of a new ultrasound reflection technique. A compact implementation of the new measuring technique is described in this article. It allows the investigation the flow structure of the dispersed gas phase in real multiphase flows within arbitrary large reaction vessels. Measurements have successfuly been performed even in complex biotechnological and chemical production systems. The measuring device exploits the Doppler–shift of ultrasound pulses upon reflections at the surfaces of moving bubbles. Only a single measuring probe needs to be introduced into the dispersion. Bubble velocity distributions can be obtained within a few minutes, even during production processes in highly viscous media. The device is simple to use, since it is fully automized by means of integrated microprocessors.
Mixed convection heat transfer enhancement through latent heat transport in vertical parallel plate channel flows
Authors: Yan W.‐M.
Published: March 2009

A detailed numerical study has been performed to examine the heat transfer enhancement through latent heat transport, in conjunction with the evaporation of a liquid film, in laminar mixed convection channel flows. Results for Nusselt numbers are presented for the air–water and air–ethanol systems under various conditions. Considerable augmentation in heat transfer due to the exchange of latent heat during the evaporation process was clearly demonstrated. The results show that the heat transfer is dominated by the transport of latent heat exchange.
Reactive distillation of pyridine mixtures with an organic acid. II. Parametric sensitivity and optimization of the process
Authors: Duprat Françoise , Gau Georges
Published: March 2009

A process of separation of close‐boiling mixture by reactive distillation, exemplified by 3‐/4‐picoline separation through complexation with trifluoroacetic acid, has been analyzed in detail by numerical simulation. In such a process, the separation selectivity is supplied by a reversible chemical reaction and a displacement agent is used to regenerate the isomers. Parameter sensitivity analysis has shown the fundamental role played by the displacement agent in the regeneration as well as in the separation when the two isomers have to be recovered with the same purity. Optimization has shown that the displacement agent should ideally have an affinity for the reactive agent intermediate between that of the isomers to be separated. This affinity is measured by the ratio of the relative volatility to the chemical selectivity.
Experimental determination of P‐X, L=G critical locus and UCEP for Biphenyl‐Co2 mixtures
Authors: Zhang D. , Wang L. , Sheng W. , Lu B. C. Y.
Published: March 2009

Solubility of CO2 in biphenyl was measured isothermally at three temperatures at pressures up to the liquid‐gas critical points. A cross‐over region where the solubility isotherms converged was observed at a pressure of about 36 MPa. The upper critical end point (UCEP) for the binary mixture was established to be 328.5 K, 48.5 MPa and 0.18 mole fraction of biphenyl by means of an intersection method. In addition, the solubility data were correlated by means of the Peng‐Robinson (1976) equation using three different sets of mixing rules. The calculated results indicate that the mixing rule proposed by Schwartzentruber et al. (1987) yields the lowest deviation.
Settling velocities of particles in bubbly gas‐liquid mixtures
Authors: Smuk D. , Scott D. S. , Macintyre R. D. , Reilly I. G.
Published: March 2009

The axial dispersion‐sedimentation model is commonly used to describe the axial concentrations of solids in three phase bubble columns at low liquid velocities. When the two parameters of this model, the particle settling velocity and the solids axial dispersion coefficient, are uncoupled by the use of various assumptions, physically unrealistic values of these parameters often result.

Direct experimental measurements of solids settling rates in bubbly gas‐liquid mixtures were carried out. The measured mean settling velocities decreased slightly with gas flow rate and were equal to or slightly less than the single particle free settling velocity in the liquid alone. Solids axial dispersion coefficients were also obtained from the solids settling rate distribution data, and gave values considerably less than the experimental liquid axial dispersion coefficient.
Turbulent circulation in bubble columns from eddy viscosity distributions of single‐phase pipe flow
Authors: Luo Hean , Svendsen Hallvard F.
Published: March 2009

The exact prediction of the flow structure in bubble columns is important for their design and scale‐up. This paper proposes a theoretical model for the liquid circulation on the basis of Reynolds equation of motion and the eddy viscosity distribution of single phase pipe flow, and presents a derivation of an analytical equation for the axial liquid velocity profiles that is fast and easy to use. The model shows a strong analogy for the eddy viscosity between multiphase and single‐phase systems, and how both eddy and molecular viscosities affect the flow. The velocity profiles calculated from the model are shown to agree well with reported experimental data for both low and high viscosity fluids.
Thermal and catalytic cracking of n‐Heptane in presence of CaO, MgO and Calcined Dolomites
Authors: Taralas Georgios , Vassilatos Vassilios , Sjöström Krister , Delgado Jesus
Published: March 2009

Experimental kinetic data on n‐heptane pyrolytic and catalytic steam cracking, and product distribution data were obtained at reaction temperatures from 700° to 800°C at atmospheric pressure. The overall thermal cracking of n‐heptane was compared to the cracking in presence of the basic catalysts MgO, CaO (low surface quicklime), and calcined dolomites.
Salt dissolution in drilling muds — a generalized correlation for mass transfer in non‐newtonian fluids
Authors: Darby Ron , Forsyth Jackie
Published: March 2009

The rate of dissolution of rock salt in drilling mud was measured as a function of flow rate and temperature under conditions simulating those in a well. A water based drilling mud, containing about 10% solids and additives was used, as well as a polymer “mud” composed of a Xanthan gum polymer solution and 5% salt, but no solids. The non‐Newtonian muds were pumped through a “slit” flow cell, with a slab of rock salt flush with one side of the cell wall. The data (including water over the same range of conditions) were described by a mass transfer coefficient, and were correlated in dimensionless form based on the theoretical solution of the analogous heat transfer problem, adapted to non‐Newtonian fluids. The non‐Newtonian properties were described by an effective viscosity, which is consistent with either the power law or Bingham plastic viscosity model.
Phase behaviour of CO2 ‐bitumen fractions
Authors: Eastick Robert R. , Svrcek William Y. , Mehrotra Anil K.
Published: March 2009

The phase behaviour of Cold Lake bitumen and its five fractions (or “cuts”) saturated with carbon dioxide is examined. The two lightest fractions (bp < 510°C) were clear liquids, whereas the third and fourth fractions were dark and viscous, i.e. much like the whole bitumen. The fifth fraction was a glass‐like solid, with a softening temperature of approximately 100°C. The vapour‐liquid equilibrium (VLE) data for the bitumen and bitumen fractions saturated with CO2 were collected at temperatures from 25 to 150°C and pressures up to 10 MPa. Experiments were also performed at conditions under which pure CO2 exists as a liquid. The VLE and LLE data were correlated with the Peng‐Robinson equation of state by modeling each bitumen fraction as one pseudocomponent whose critical properties and acentric factor were estimated from correlations available in the literature.

The CO2‐solubility and density data were used to develop generalized correlations for the critical pressure and the binary interaction parameter (kij) in terms of molar mass and critical temperature. The model was subsequently used to predict the solubility of CO2 in the whole bitumen which was represented as a 5‐component mixture. A correlation for Cut i‐Cut j binary interaction parameter (kij) was developed in terms of temperature and the difference in hydrocarbon molar masses. The average deviation in the predicted and experimental CO2‐solubility in the whole Cold Lake bitumen was less than 7%.
Gas entrainment behavior of vertical plunging liquid jets in terms of changes in jet surface length
Authors: Kusabiraki Daisuke , Yamagiwa Kazuaki , Yasuda Morihiro , Ohkawa Akira
Published: March 2009

For a vertical jet system using various liquids, the shape change of liquid jets discharged from nozzles having different nozzle aspect ratios was evaluated in terms of the surface length lm of the jet flow, and the relation between the change of lm and the gas entrainment behavior was investigated. It was found that the way of changing of lm with varying operating conditions or the liquids corresponded well to that of changing of the gas entrainment rate Qg, that is, the change of lm of the jet before plunging could be closely related to the change of Qg.
Isothermal vapour‐liquid equilibria for the isopropyl benzene‐ammonia system
Authors: Noda Katsuji , Murakami Shigeki , Uchida Shigeo , Ishida Kiyoharu
Published: March 2009

Vapour‐liquid equilibrium data were obtained for the isopropyl benzene‐ammonia system at 273.15, 288.15, 293.15 and 298.15 K. This system has an upper critical solution temperature at 293.15 K. Since the liquid mixture changes from two liquid phases to one liquid phase with rising temperature, vapour‐liquid‐liquid equilibria also are evaluated. Experimental vapour‐liquid equilibrium data were compared with calculated values from the UNIQUAC equation, and show good agreement.
On the relation between activity coefficients and excess gibbs energy functions
Authors: Cheluget E. L. , Wilczek‐vera G. , Vera J. H.
Published: March 2009

The relation between activity coefficients and excess Gibbs energy functions for mixtures of electrolytes and nonelectrolytes is examined under a general framework. It is shown that the use of molality, instead of mole fraction, as a composition variable leads to unusual expressions for the activity coefficients of both solvents and solutes. Explicit expressions for activity coefficients in binary and multicomponent mixtures are derived and the importance of selecting proper standard states is highlighted.
A new four‐parameter cubic equation of state for mixtures. Vapor–liquid equilibrium calculations
Authors: Jan Dong‐Syau , Tsai Fuan‐Nan
Published: March 2009

A new four‐parameter cubic equation of state has been recently developed and has accurately reproduced the thermodynamic properties of pure substances including polar fluids. In this work we apply the equation to vapor‐liquid equilibrium calculations through the introduction of different mixing rules. Various classes of mixtures are investigated at low pressures as well as at high pressures. The calculated results show that the equation with the Huron‐Vidal mixing rules offers better correlations for all types of systems over a wide range of temperature and pressure.
Prediction of solubility of hydrogen in petroleum cuts using modified unifac
Authors: Fahim Mohamed A. , Elkilani Amal S.
Published: March 2009

The solubility of hydrogen in different crude oil fractions was estimated using the modified UNIFAC group contribution method. Functional group concentrations were estimated from suggested group model structures. An optimization technique was carried out on critical properties to test the group model structure. The validity of this approach was verified by comparing the predicted and experimental hydrogen solubilities. The experimental hydrogen solubilities were measured by means of pulse response techniques.
Influence de la concentration des agents tensio‐actifs sur la vitesse terminale d'ascension des gouttes
Authors: Gonzalez‐Tello P. , Camacho F. , Jurado E. , Bailon R.
Published: March 2009

On a étudié l'ascension des gouttes dans de l'eau contaminée avec deux agents tensio‐actifs, le dodécylhydrogénosulfate sel de sodium (L.S.S.) et Teepol, dans l'intervalle 200 < NRep < 1000. Les phases dispersées utilisées sont le cyclohexane, le benzène, le toluène et le n‐heptane. Toutes les expériences ont été faites à la température constante de 30°C. Nous avons vérifié que la présence des deux agents tensio‐actifs diminue la vitesse terminale d'ascension des gouttes à mesure que la concentration de l'agent tensio‐actif et le diamètre des gouttes augmentent. Ce phénomène s'accentue, pour les mee'mes valeurs de tensions interfaciales, dans le cas du Teepol.

On propose une équation pour le calcul du diamètre critique des gouttes et une autre pour la vitesse d'ascension des gouttes. Ces équations mettent en évidence l'influence de la nature chimique de l'agent de surface et reproduisent les résultats expérimentaux avec des écarts inferieurs à 10%.
Holdup for two‐phase flow of gas‐non‐newtonian liquid mixtures in horizontal and vertical pipes
Authors: Das S. K. , Biswas M. N. , Mitra A. K.
Published: March 2009

The paper deals with the experimental investigations carried out to evaluate holdup for gas‐non‐Newtonian (pseudoplastic) liquid mixtures in vertical and horizontal flow in pipes. Correlations developed predict holdup in slug flow regime with acceptable statistical accuracy.
Parameter estimation in simultaneous phase and reaction equilibria
Authors: Dovì V. G. , Reverberi A. P.
Published: March 2009

The estimation of parameters of models describing simultaneous phase and reaction equilibria is generally difficult to accomplish, due to strong correlation between the parameters. We show in this paper that these models possess intermediate properties between reduced and implicit models. This makes it convenient to develop ad‐hoc algorithms for this class of problems which are of considerable importance in process design. We present a method for parameter estimation based on implicit differentiation, which makes it possible to use a gradient algorithm with respect to a reduced number of parameters, which greatly enhances global convergence.
Sedimentation of a sphere along the axis of a long square duet filled with non‐newtonian liquids
Authors: Balaramakrishna P. V. , Chhabra R. P.
Published: March 2009

Based on extensive experimental results, it is shown that the retardation effect caused by the confining walls on the free settling velocity of a sphere is smaller with square walls than that with cylindrical boundaries. This is true for both Newtonian and power law fluids, provided the particle Reynolds number is small (< about 5). The values of the wall factor for Newtonian liquids are in excellent agreement with theory (up to R / L ≤ 0.1) while those for power law fluids have been correlated empirically via a linear relationship. The results reported here encompass the following ranges of conditions: 1 ≥ n ≥ 0.7; Re < 15 and 0.024 < R/L < 0.238.
Phase behaviour prediction in supercritical systems using generalized solute critical properties
Authors: Sigmund P. M. , Trebble M. A.
Published: March 2009

Trebble and Sigmund (1990) have recently published a generalized form of the Peng‐Robinson (1976) equation of state in which binary interaction parameters are predicted as a function of the species critical volumes, dipole moments, and quadrupole moments. In this study, the critical properties of solutes heavier than normal hexane are correlated against molar mass, normal boiling temperature, and group type (i.e. paraffinic, olefinic, naphthenic or aromatic). This extension further facilitates the use of the generalized Peng‐Robinson equation in calculating phase behaviour of supercritical systems in which solute critical properties are unknown or uncertain. Calculation of phase behaviour using the extended correlation is shown to be of the same quality as the previous generalization (which required solute critical constants) for 38 binary systems covering broad temperature and pressure ranges.
Solubility of hydrogen in a white oil
Authors: Schofield B. A. , Ring Z. E. , Missen R. W.
Published: March 2009

The solubility of hydrogen in a white mineral oil has been measured at pressures of 1.48 to 10.44 MPa at each of four temperatures (573, 603, 623, 643 K), in conjunction with a study of hydrodesulphurization in a trickle‐bed reactor. The solubility varies from a hydrogen mole fraction of 0.056 at the lowest [T, P] to 0.262 at the highest. The solubility increases with increasing pressure and temperature. It can be represented by an equation suggested by using Krichevsky‐Ilinskaya and van't Hoff expressions.
Combustion of single char particles in a turbulent fluidized bed
Authors: Halder P. K. , Datta A. , Chattopadhyay R.
Published: March 2009

The combustion of single bituminous char particles (4‐12 mm diameter) was studied in a turbulent fluidized bed operated at 1098 K using air as the fluidising medium. Results indicated that particles burn with constant density following a shrinking sphere model. Burning rates are much higher than those observed in a bubbling fluidized bed. The rate of transfer of oxygen to the particle surface is also higher than that observed in bubbling beds. A model is proposed to calculate the Sherwood numbers of the burning carbon particles. Experimental values of the Sherwood numbers agree well with those predicted from the model.
Devolatilization and char burning of coal particles in a fluidized bed combustor
Authors: Jia Lufei , Becker H. A. , Code R. K.
Published: March 2009

Devolatilization and char burning were studied in an electrically heated bench‐scale fluidized‐bed reactor at 750 to 900°C bed temperature, gas oxygen mole fractions ranging from zero to 0.21, superficial gas velocities from 0.3 to 0.7 m/s and coal particle diameters 5 to 35 mm. The coals investigated include lignite, bituminous and anthracite. The coal devolatilization and char burning times, H/C ratio histories, and particle fragmentation were measured. Statistical correlations with the operating variables were developed for the devolatilization time. A mathematical model is given for the combustion of char. Most predictions of the model agree quite well with the experimental results.
Influence of tube inclination on the flow regime boundaries of condensing steam
Authors: Nitheanandan T. , Soliman H.M.
Published: March 2009

Flow regime data of condensing steam inside an inclined 13.4 mm ID tube are presented. The effect of upward and downward inclinations within ± 10° on the different transition lines is discussed. In all test runs, complete condensation has been achieved inside the condenser, with or without full tube at exit depending on the total mass flow rate and inclination angle. It is shown that the zones occupied by the wavy and slug regimes experience significant shifts, whereas the effect on the annular flow boundary appears to be insignificant at the present small inclination angles. The present data sets are compared with adiabatic gas‐liquid flow regime maps developed analytically and experimentally for horizontal and inclined tubes. Deviations due to the condensation process are observed; however, consistent trends are identified among the two types of flow.
The effects of pressure and temperature on the catalytic oxidation of hydrogen sulfide in natural gas and regeneration of the catalyst to recover the sulfur produced
Authors: Dalai Ajay K. , Majumdar Amitabha , Chowdhury Aminul , Tollefson Eric L.
Published: March 2009

The influence of pressure up to 5600 kPa and temperature up to 175 °C on the oxidation of low concentrations of H2S in natural gas was studied in a fixed bed reactor over an activated carbon catalyst. Operation of this system at 5600 kPa provides higher catalyst activity (virtually 100% H2S conversion) over a longer period of time and with lower selectivity to SO2 than when operated at atmospheric pressure. The desorption of sulfur from a loaded catalyst occurs first from the macropores (> 100 nm) of the catalyst which contain a substantial portion of the sulfur load and then from the micropores (< 100 nm). This study also indicated that the sulfur recovery process is both rapid and effective at 327°C.
Hydrodynamics of a flowing gas‐solids suspension in a tube at high angles of inclination
Authors: Ginestet A. , Guigon P. , Large J. F. , Sen Gupta S. , Beeckmans J. M.
Published: March 2009

A study was made of pneumatic transport of particles of sand suspended in air in a 31.8 mm diameter Plexiglas tube inclined at either 72 or 90 degrees with respect to the horizontal plane. The solids holdup, pressure gradient and pressure drop fluctuations over a 4.55 m test section were measured as functions of the air velocity and the solids flux. Previously observed sudden changes in slope of plots of solids holdup versus solids flux at constant gas velocity in a vertical tube (Mok et al., 1989), which were identified as transition points between dilute and dense phases, were confirmed and extended to inclined tubes. Breaks were also found in plots of pressure drop fluctuations versus solids flux at constant gas velocity.
A model for gas flow in jet spouted beds
Authors: Olazar M. , San José M. J. , Peñas F. J. , Aguyo A. T. , Arandes J. M. , Bilbao J.
Published: March 2009

A model of general application that is based on the definition of streamlines and that is in agreement with the bed geometry has been proposed in order to describe the gas flow in a jet spouted bed in conical contactors. The model quantifies the dispersion in the direction of the streamlines by using a characteristic modulus.

The validity of the model has been experimentally proven on the basis of the measurement and analytical correlation of gas velocity profiles at different radial and longitudinal positions in the contactor, and of the application of the stimulus response technique for the calculation of the residence time distribution function.
Prediction of lower/upper limiting viscosities
Authors: Kozicki W. , Kuang P. Q.
Published: March 2009

An analysis based on steady uniform laminar flow of a non‐Newtonian fluid in a tube is presented which predicts Newtonian flow behaviour in the limits of zero and infinite shear, respectively. It is shown that an upper limiting viscosity occurs in the limit of infinite shear for a fluid with or without a yield stress, whereas a lower limiting viscosity is obtained for a fluid without a yield stress in the limit of zero shear. For a fluid with a yield stress, an infinite viscosity is found in the limit as the shear stress approaches the yield stress.
Experimental study of mixing performances using steady and unsteady jets
Authors: Simon M. , Fonade C.
Published: March 2009

This paper deals with the experimental study of mixing characteristics by means of steady and unsteady jets. Investigations were carried out with one and two steady jets, and with two alternate intermittent jets, supplying 0.1 m3 and 70 m3 tanks. From the data obtained from several sensors put into the tank, the signification of the mixing time as applied to the tank is discussed. A Reech‐Froude similarity appears to be a good way in scaling the results obtained on either 0.1 m3 or 70 m3 models. Combining the specific momentum of the jets and the tank characteristics, a mixing time factor M is deduced which permits the evaluation of the mixing time. The efficiency of different configurations of jets are then compared through a degree of transient inhomogeneity and required power.
Roles of ZSM‐5 modifier agents in selective toluene disproportionation
Authors: Uguina Maria A. , Sotelo Jose L. , Serrano David P.
Published: March 2009

Selective toluene disproportionation has been studied over ZSM‐5 zeolites modified with P, Si and Cs compounds. For the P and Si modified samples, p‐xylene proportion in the primary product was 100% due to the diffusional control on the internal xylene isomerization. The number and strength of the acid sites are reduced by the three modifier agents but a relationship between para‐selectivity and the decrease of the acid strength has not been observed. The most para‐selective samples have been those modified with Si which has been related to the deposition of this agent on the external surface of the zeolite crystals avoiding the primary product isomerization.
Characterization of flooding in a wirz extraction column
Authors: Rincón‐Rubio L. M. , Kumar A. , Hartland S.
Published: March 2009

The flooding behaviour of a 150‐mm diameter Wirz‐II extraction column has been investigated for six different liquid‐liquid systems. Normally, flooding occurred by phase inversion but when the density difference was low could also occur by entrainment of dispersed‐phase drops at the continuous‐phase exit. Empirical expressions for flooding velocities and holdup at flooding are derived in terms of the operating variables, column geometry and physical properties of the liquid systems.
Residual oil cracking combined with hydrogen production by steam‐iron reaction
Authors: Fukase Satoshi , Suzuka Teruo
Published: March 2009

A new residual oil upgrading process has been developed. Residual oils were cracked over an iron oxide catalyst with simultaneous generation of hydrogen. The newly‐developed iron oxide catalyst containing CaO and Cr2O3 was found to be a good catalyst for this process because it exhibited stable activity in the steam‐iron reaction in the laboratory experiment and also in a large scale pilot plant. Effects of these foreign oxides on redox cycles were investigated. The catalyst was designed so as to maintain the stoichiometric balance between the reduction of magnetite and the oxidation of wustite by adding CaO and Cr2O3.
Thermodynamics and kinetics of the kraft causticizing reaction
Authors: Wang L. , Tessier P. J.‐C. , Englezos P.
Published: March 2009

A methodology for the calculation of the equilibrium of the causticizing reaction of pure sodium carbonate solutions at 100°C without any adjustable parameters is presented. The methodology is extended to compute the effect of sodium sulfide. The causticizing reaction was found to be slightly endothermic at 100°C. The caculated results were found to be in good agreement with experimental data. An empirical kinetic model for the causticizing reaction is also presented. The model takes into account the variations in both green liquor composition and lime quality and can yield the causticizing efficiency directly. The calculated results of the causticizing efficiency were found to be in good agreement with experimental data from several Canadian pulp mills and reflected the effect of the variation in lime quality.
Evaluation of capital cost data: Part 8: Liquid waste disposal with emphasis on biological treatment
Authors: Wright David G. , Woods Donald R.
Published: March 2009

Capital cost correlations are given for aeration basins, mechanical aerators, diffused aeration, conventional activated sludge process, extended aeration, contact stabilization, oxidation ditch, rotating biological contactor, trickling filter, aerobic lagoons, facultative lagoon, aerated lagoons and liners. Most of the correlations are accurate to ±30%, expressed in Canadian dollars and adjusted to a Marshall and Swift value of 1000. Details as to what components are included in the cost are given. Data are given for the labour and material costs to create a working process module. Data for oxidation ditches are accurate to ±50%.

To put the current data into perspective, several hundred sources of cost data were analyzed. The major correlations are compared, on a consistent basis, with current data.
Heat transfer mechanism due to particle convection in circulating fluidized bed
Authors: Qi Chunming , Farag Ihab H.
Published: March 2009

The nature of heat transfer in circulating fluidized beds (CFBs) by particle convection was revealed from the experimental results of the particle flux in the lateral direction. As particles contact and rebound from the heat transfer surface because of their lateral motion, they establish a large local temperature gradient. Heat from particles is then transferred primarily through the gas to the heat transfer surface. The data of the lateral particle flux provide a basis to establish a model of heat transfer in CFBs.
Loading, draining and hold‐up in periodically operated trickle‐bed reactors
Authors: Hasokowati Wahyu , Hudgins R. R. , Szlveston P. L.
Published: March 2009

Periodic interruption of liquid flow in co‐current trickle beds appears to be an attractive mode of operation. For modelling these intermittent‐flow reactors, loading and draining times must be known. Experiments were undertaken using beds of activated carbon with water and air as the fluid phases. Loading time was taken as the time to water breakthrough. The gas flow was continuous while the time between the end of drainage and the start of filling was varied to simulate different periods. Drainage experiments followed the liquid flow leaving the bed as a function time. Liquid hold‐ups were determined after the filling and draining measurements. Variables considered were particle size, gas and liquid velocity. Loading closely follows the plug flow model; drainage shows tailing but does not follow literature models. Static and dynamic hold‐ups at zero gas flow agree with literature correlations for the larger particle size used. A gas velocity effect on both static and dynamic hold‐up was observed.
Coal gasification in a jet‐spouted bed
Authors: Tsuji Toshiro , Uemaki Osamu
Published: March 2009

Coal gasification has been studied for the production of synthesis gas by use of a laboratory‐scale, two‐stage, jet‐spouted bed reactor. Tests were conducted in the dry ash mode with oxygen‐steam mixtures. The effects of operating conditions on the gasification performance were investigated at atmospheric pressure and temperatures up to 1150°C. Carbon conversions of 75% to 97% and cold gas thermal efficiencies of 62 to 78% were obtained for Taiheiyo coal. Both the carbon conversion and thermal efficiency were mainly affected by the oxygen/coal ratio. The product gases contained 36‐41% hydrogen and 30‐43% carbon monoxide.
The oxidation of valeric acid in aqueous solution
Authors: Nikolaou N. , Abatzoglou N. , Gasso S. , Chornet E.
Published: March 2009

The liquid phase oxidation of an aqueous solution of a lower fatty acid, valeric (pentanoic) acid, has been studied at high temperatures (240−325°C) and pressures (10.3‐10.4 MPa) in a batch autoclave reactor. The objective of the study was to develop a mechanistic understanding of the wet oxidation of industrial wastewaters contaminated with vegetable oils. Valeric acid was chosen as the prototype molecule. High performance liquid chromatography (HPLC) has been used to identify the liquid products and estimate their concentrations as a function of the extent of oxidation. Moreover the technique of GC‐MS has also been used to obtain information on specific intermediate oxidation products that could not be identified by HPLC. The gaseous products of the reaction have been also identified and quantified. A detailed reaction mechanism is proposed based on free radical reactions.
Natural convective heat transfer from open vertical tubes
Authors: Baird M. H. I. , Legree B. A.
Published: March 2009

Natural convection heat transfer in vertical tubes is described by a one‐dimensional dispersion model similar to that used previously for fluid mixing in the presence of an unstable density gradient. Temperature profiles have been measured in air in 2 m high insulated vertical tubes (21.3, 24.5, 27.7 cm internal diameter), closed at the bottom and open at the top, and heated at the bottom with a known heat flux. The effective mixing lengths for eddy heat transport are of the same order as the tube diameters.
Cell and surfactant separation by column flotation
Authors: Husband Devon L. , Masliyah Jacob H. , Gray Murray R.
Published: March 2009

The separation of rehydrated Saccharomyces cerevisiae and an alkyl polyglycoside surfactant by column flotation was studied as a function of wash water flow and cation concentration. Separation of cells and surfactant was measured under steady‐state conditions. Surfactant recovery in the foam concentrate was in the range of 86–95%. Yeast cells were enriched in the foam concentration by a factor of up to 11, but the recovery only reached 55%. The use of wash water was very effective for removing the cells from the foam, giving a good separation between the cells and the surfactant. Addition of chloride salts of Na, K, Ca, and Mg at concentrations in the range of 0.05‐0.1 mol/L increased both the enrichment and the recovery of yeast in the foam. The most effective salt levels for cell flotation, less than 0.1 mol/L, were in the same range of concentration as the minimum electrophoretic mobility of the cells.
Effect of H2O2 addition mode on enzymatic removal of phenol from wastewater in the presence of polyethylene glycol
Authors: Wu Jiangning , Bewtra J. K. , Biswas N. , Taylor K. E.
Published: March 2009

The effect of batch and semi‐batch additions of the stoichiometric amount of H2O2 on enzymatic removal of phenol has been studied over the phenol concentration range of 1‐10 mmol/L. It is found that the ratio between the maximum H2O2 concentration during the reaction and the initial horseradish peroxidase concentration ((H2O2)max/(HRP)o) controls the rate of phenol removal by horseradish peroxidase in the presence of the additive, polyethylene glycol. An optimum range of this ratio is determined to be between 10 and 25 μmol/U. Empirical models are proposed to predict the values of (H2O2)max/(HRP)o required to treat given phenol concentrations under different modes for adding H2O2.
Phase equilibrium data on carbon dioxide hydrate in the presence of electrolytes, water soluble polymers and montmorillonite
Authors: Englezos Peter , Hall Stephen
Published: March 2009

Equilibrium formation conditions for carbon dioxide hydrate were measured in pure water and in aqueous polymer and electrolyte solutions. The solutions that were used include: polyethylene oxide, partially (10 and 90 percent) hydrolyzed polyacrylamide, sodium chloride and calcium chloride. Experiments with solutions containing both electrolyte and polymers were also performed. It was found that the electrolytes exhibited a substantial inhibiting effect whereas the polymers only slightly altered the equilibrium hydrate formation conditions. The measured equilibrium formation pressures were compared with the predictions from existing hydrate equilibria methods and were found to be in good agreement. The effect of montmorillonite was also studied and it was found that it did not affect the equilibrium hydrate formation conditions. A total of 101 experimental measurements are reported.
Microwave assisted barking of frozen wood
Authors: Gilbert Allan F. , Turcotte Camille
Published: March 2009

Thawing pulpwood with microwave energy could be an effective means to improve winter barking operations in Canadian interior mills. Complete bark thawing requires 140 MJ per tonne of wood for average 25 cm diameter logs at 90 mass % moisture, dry basis. However, complete thawing may not be necessary, as warming both spruce and aspen bark from −20°C to −5°C, decreases the bark/wood bond strength from 2.5–4.5 MPa to room temperature values of 0.5–1.5 MPa. This improves the economics of winter operation, but the expenditure for capital which has no year‐round use is not easily justified. Also the design of safe large‐scale microwave generators and applicators remains a technical challenge.
Purification of wet process phosphoric acid by solvent extraction liquid‐liquid equilibrium at 25 and 40°C of the system water‐phosphoric acid‐methylisobutylketone
Authors: Feki M. , Fourati M. , Chaabouni M. M. , Ayedi H. F.
Published: March 2009

Solubility and liquid‐liquid phase equilibrium data are presented for the ternary system water‐phosphoric acid‐methyl isobutyl ketone at 25 and 40°C. Binodal curves, tie lines and distribution curves have been determined. Hand's method has been used to correlate tie lines and to calculate coordinates of plait points. The heterogeneous region at 40°C appeared to be slightly broader than that at 25°C, and the slopes of tie lines somewhat higher: the solubility of this system increases with decreasing temperature. The distribution curves indicated that methyl isobutyl ketone was an effective extractant for concentrated phosphoric acid solutions only.