bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalyst decay in the presence of chain processes in catalytic cracking
Authors: Rice N. M. , Wojciechowski B. W. 
Published: March 2009

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractPhase 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

AbstractThe 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.
Flow of power law liquids through particle assemblages at intermediate reynolds numbers
Authors: Jaiswal A. K. , Sundararajan T. , Chhabra R. P. 
Published: March 2009

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractA 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

AbstractSolubility 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

AbstractThe 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

AbstractThe 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

AbstractExperimental 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

AbstractThe 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

AbstractThe 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

AbstractFor 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

AbstractVapour‐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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractOn 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

AbstractThe 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

AbstractThe 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

AbstractBased 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

AbstractTrebble 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

AbstractThe 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

AbstractThe 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.