bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative analysis of combined impingement and through air drying of paper
Authors: Chen G. , Crotogino R. H. , Douglas W. J. M. 
Published: March 2009

AbstractModels were developed and verified to represent the water removal rate data of the two components of combined impingement and through air drying process. Eight physically meaningful parameters were identified, determined, correlated and analyzed. The increasing rate period is extended by impingement water removal. Constant impingement water removal decreases linearly with through flow ratio at a fixed impingement exhaust air flow. Constant through flow water removal is independent of the impingement air. Critical moisture content relates with through flow ratio parabolically. The maximum through flow water removal rate depends on the slope of the paper temperature increase and the extent of the secondary increasing rate period which increases with paper basis weight and drying air temperature, but decreases with through flow ratio and initial moisture content.
Cold flow velocity measurements in recovery boilers: Part I: Interaction of primary and secondary air flows
Authors: Karidio I. , Uloth V. , Markovic C. , Thorn P. 
Published: March 2009

AbstractCold air flow velocities were measured in a commercial recovery boiler during shutdown periods, using hot‐wire anemometers, modified to indicate direction. Five tests were carried out using different primary and secondary air configurations. The conditions tested included arrangements recommended by others to improve gas flow uniformity, as well as unrealistic extremes to be used in the evaluation of computational fluid dynamic models. The measurements demonstrated the inherent unsteadiness of recovery boiler flows and confirmed that balanced air flows through opposed walls result in a central region of high velocity upward flow. Interlacing of the secondary air significantly reduced the peak velocity and flattened the upward velocity profile at the liquor gun level.
Characterization of the surface area of overflow droplets generated by a gas‐lift pump under reduced pressure
Authors: Lee Hi Sun , Harris Ralph 
Published: March 2009

AbstractWater‐modelling experiments were carried out to characterize the surface area of overflow droplets generated by a gas‐lift pump under reduced pressure as a function of various operating parameters, namely, top pressure, gas flow rate, nozzle submergence, lift ratio and riser diameter. The liquid phase mass transfer coefficient was obtained by applying the penetration theory (Treybal, 1980; Bird et al., 1960) to the overflow generated from the riser. Under reduced pressure, churn‐turbulent flow, consisting of distorted bullet‐shaped bubbles, was predominant in the flow regime. The increase of liquid circulation rate and flight time and the decrease of droplet size increased the refining rate. Because of the large droplet size, the refining rate of molten metals was smaller than that of water.
Minimum spouting velocity of conical spouted beds
Authors: Bi H. T. , Macchi A. , Chaouki J. , Legros R. 
Published: March 2009

AbstractExisting correlations for predicting minimum spouting velocity in conical spouted beds have been found to give poor agreement with available literature data. A new correlation has been developed based on literature data to give much better prediction of the minimum spouting velocity for both small and pilot‐scale conical‐spouted beds.
The solubility of HFC125, HFC134a, HFC143a and HFC152a in n‐eicosane, n‐hexadecane, n‐tridecane and 2, 6, 10, 14‐tetramethylpentadecane
Authors: Wahlström åsa , Vamling Lennart 
Published: March 2009

AbstractThe solubility of 1, 1, 1, 2,2‐pentafluoroethane (HFC125), 1, 1, 1, 2‐tetrafluoroethane (HFC134a), 1, 1, 1‐trifluoroethane (HFC143a) and 1,1‐difluoroethane (HFC152a) in four well‐known hydrocarbons have been measured at temperatures between 293.15 and 363.15 K and pressures between 0.05 and 2 MPa. Henry's constant, and the activity coefficient for HFCs at infinite dilution, have been derived for measurements below 0.28 MPa. The measurements were made with an isochoric method and their uncertainty is less than 2% for Henry's constant and less than 3% at high pressure. For several mixtures, the experimental data have been correlated with the UNIQUAC method and binary interaction parameters have been derived, resulting in a deviation from the data of less than 4%.
The optimum plate aspect ratio for the best performance in a flat‐plate thermal diffusion column of the frazier scheme
Authors: Yeh Ho‐Ming 
Published: March 2009

AbstractThe effects of plate aspect ratio on the degree of separation, production rate and plate surface area in a flat‐plate thermal diffusion column of the Frazier scheme, have been investigated. Theoretical considerations show that when the thermal diffusion columns of the Frazier scheme are constructed with the best plate aspect ratio, maximum separation, maximum production rate or minimum plate surface area can be obtained. The optimum plate aspect ratio for maximum separation is obtained with given production rate and plate surface area, while that for maximum production rate is determined with the degree of separation and plate surface area fixed, and that for minimum plate surface area is estimated with known degree of separation and production rate. It is interesting that the optimum plate aspect ratio for maximum separation is exactly the same as that for minimum plate surface area. The maximum separation and maximum production rate are achieved without changing any total expenditure, while the design with minimum plate surface area results in minimizing the total expense.
Bubbling from nozzles submerged in water: Transitions between bubbling regimes
Authors: Kyriakides N. K. , Kastrinakis E. G. , Nychas S. G. , Goulas A. 
Published: March 2009

AbstractThe bubble formation and coalescence phenomena above submerged nozzles having diameters between 1 and 7 mm were studied visually in a stagnant water column. Air was supplied at the nozzles under constant flow rate conditions and the field of view extended from the nozzle exit up to 14 cm above it. The air Reynolds number based on the nozzle diameter covered a range between 50 and 40000. The study was focused on a unified description of the bubbling phenomena, beginning from the single bubble formation up to the jet formation, and the transitions between the various bubbling regions. It was concluded that for nozzles, as injector devices and for the air/water system investigated, the Reynolds number is the controlling variable for the bubbling phenomena above the nozzles and for the transition between the various bubbling regions.
Numerical and physical modeling of the permeability of paper to CMC and coating liquids
Authors: Poulin N. , Tanguy P. A. , Aspler J. , Larrondo L. 
Published: March 2009

AbstractThe penetration of CMC solutions and coating liquids into paper sheets was investigated experimentally and modeled using a Lucas‐Washburn equation (Lepoutre, 1978) adequately modified to account for the dynamic contact angle and the coating fluid rheology. A numerical simulation of the fluid penetration based on the finite element resolution of the Navier‐Stokes equations was carried out as well. The numerical predictions and the predictions of the Lucas‐Washburn equation were compared with the experimental data showing the limitations of the models.
Operation of a catalytic reverse flow reactor for the purification of air contaminated with volatile organic compounds
Authors: Van De Beld L. , Westerterp K. R. 
Published: March 2009

AbstractCatalytic oxidation in a reverse flow reactor is an attractive process for the decontamination of air polluted with volatile organic compounds (VOCs). In this paper several aspects of operating this type of reactor for air purification under strongly varying conditions will be discussed.For a successfit operation of such reactor a minimum amount of combustibles is required, and a simple theory is developed to predict this minimum value. This minimum amount is strongly influenced by the reaction kinetics, the heat transport in the packed bed and the adiabaticity of the reactor. To cope with a too low temperature level in the reactor for a complete conversion, an electrical heating device should be installed in the centre of the reactor bed to increase locally the temperature rapidly and efficiently. To control the maximum temperature in case of too high concentrations, extra air should be added to the feed.
Corresponding‐states and parachor models for the calculation of interfacial tensions
Authors: Zuo You‐Xiang , Stenby Erling H. 
Published: March 2009

AbstractA generalized corresponding‐states model based on two reference fluids and a parachor correlation were developed for the prediction of interfacial tensions for non‐polar and weakly polar pure fluids and mixtures. Pure methane and n‐octane were chosen as reference fluids of the corresponding‐states model. The two models were tested on 86 pure substances, more than 30 binary and multicomponent mixtures, 11 naphtha reformate cuts, 6 petroleum cuts and 2 North Sea oil mixtures. The calculated results were found to be in good agreement with experimental data.
Kinetic models for non‐homogeneous complex systems with a time‐dependent rate constant
Authors: Montané Daniel , Overend Ralph P. , Chornet Esteban 
Published: March 2009

AbstractThis paper discusses a phenomenological kinetic model which describes the conversion of complex non‐homogeneous systems. The model embodies the concept of a severity parameter as a descriptor of the extent of reaction of the complex system. Temperature, time and catalyst concentration are simply and conveniently regrouped in the definition of the severity parameter. The link between our model and formal kinetics can be made via a time‐dependent rate constant. Such dependency expresses the concept that in a complex non‐homogeneous system the chemical acts leading to reaction are first order processes constrained either by microstructural effects, diffusional limitations, geometric discontinuities, or in generic terms by fractal considerations. The observable effect is the change in reactivity with extent (or time) of reaction. Our approach permits to model such systems via a set of four key markers characteristic of the overall reaction. The development of the model, the significance of the markers and their application to the hydrolysis of lignocellulosic biomass as a case study are presented and discussed.
Optimisation de l'hydrolyse des protéines du lactosérum en utilisant des détergents commerciaux enzymatiques et non‐enzymatiques
Authors: Argüello M. Ángeles , Elzo Dominique , Riera Francisco A. , Álvarez Ricardo 
Published: March 2009

AbstractL'objectif principal de ce travail est la caractérisation des effets produits par l'utilisation de détergents commerciaux sur les protéines du lactosérum, dans le but de sélectionner un détergent efficace pour le nettoyage des membranes inorganiques colmatées dans les procédés de fractionnement de ces protéines. On a étudié l'influence des variables temps, pH, température et concentration du détergent sur le degré d'hydrolyse du substrat (protéines du lactosérum). On a déterminé aussi le type et la taille des peptides produits au cours de l'hydrolyse. Les résultats les plus performants on été obtenus avec le détergent P3‐Ultrasil 62.
Bubble size and mass transfer coefficients in dual‐impeller agitated reactors
Authors: Bouaifi Mounir , Roustan Michel 
Published: March 2009

AbstractThe study relates to the mass transfer and the bubble size in a non standard vessel equipped with various dual‐impeller combinations. The effects of the rotational speed, gas flow rate, impeller type and diameter are investigated. The volumetric mass transfer coefficient kLa and the bubble size dbs were studied. The liquid side mass transfer coefficient kL and the volumetric interfacial area a were estimated separately. A comparison has been made with some existing correlations.
Numerical investigation of the performance of several static mixers
Authors: Rauline Damien , Tanguy Philippe A. , Le Blévec Jean‐Marc , Bousquet Jacques 
Published: March 2009

AbstractThe performance of six static mixer (Kenics, Inliner, LPD, Cleveland, SMX and ISG) are compared using 3D numerical simulations in laminar creeping flow regime. Numerical pressure drop results are tested against experimental ones, showing overall a good agreement. Besides pressure drop, four criteria (extensional efficiency, stretching, mean shear rate and intensity of segregation) are chosen to compare the static mixers. It appears that Kenics, Inliner, LPD and Cleveland mixers are rather similar. The ISG mixer seems better than this first group of mixers, but pressure drop is too high compared to other advantages. From our numerical results, SMX appears to be the most efficient of the six compared static mixers.
Matériaux anodiques pour électrolyseurs
Authors: Devilliers Didier , Groult Henri 
Published: March 2009

AbstractCet article passe en revue les principaux types de matériaux anodiques actuellement utilisés dans les électrolyseurs industriels. Les mécanismes des réactions mises en jeu sont détaillés dans chaque cas, des exemples d'application et les perspectives offertes sont analysés. Une place importante est dédiée au carbone et aux oxydes de métaux précieux qui ont conduit au développement des “anodes dimensionnellement stables”. Dans ce dernier cas, on décrit le phénomène de désactivation par formation d'une couche passive entre le métal substrat et l'oxyde électrocatalytique.
Simulations of the effect of hydrodynamic conditions and properties of membranes on the catalytic performance of a fluidized‐bed membrane reactor for partial oxidation of methane
Authors: Ostrowski Thomas , Mleczko Leslaw 
Published: March 2009

AbstractIn a fluidized‐bed membrane reactor the selectivity of separation can be controlled by influencing the hydrodynamics of the fluidized bed. In this reactor type, with the mass transport limitation between bubbles and the emulsion phase, even with the non‐selective membranes, high selectivity of separation can be achieved. This opens the possibility for applications of membrane reactors for reaction systems for which selective membranes do not exist, e.g. when Knudsen‐type membranes or form‐selective separation can not be applied. This paper is aimed at explaining the interaction between the selectivity of separation and the hydrodynamics of the fluidized bed by means of simulations that were performed for a fluidized‐bed membrane reactor for catalytic partial oxidation of methane.
Removal of acetic acid from water by catalytic distillation. Part 2: Modeling and simulation studies
Authors: Xu Zhanping , Afacan Artin , Chuang Karl T. 
Published: March 2009

AbstractA simulation program has been established by incorporating basic models for reaction kinetics, vapor–liquid equilibrium and mass transfer into Aspen Plus (Aspen Technology Inc., 1996) to simulate the catalytic distillation process for the removal of dilute acetic acid from water. The simulated concentration profiles agree well with those measured under various operating conditions.
Equilibrium conditions for the hydrogen sulfide hydrate formation in the presence of electrolytes and methanol
Authors: Mahadev Kal N. , Bishnoi P. Raj 
Published: March 2009

AbstractNatural gas industry encounters systems that consist of gases like CO2 and H2S, and aqueous solutions of methanol and mixed electrolytes. A knowledge of the phase behavior of such systems, including hydrate formation, is essential in gas production and the design of facilities for gas transportation and processing. Recently, Dholabhai et al. (1997, 1996) and Bishnoi and Dholabhai (1998) described equilibrium conditions for CO2 and gas mixtures containing CO2 in the presence of methanol, electrolytes and ethylene glycol. In the present work aqueous three phase (aqueous liquid solution, vapor and incipient hydrate) equilibrium conditions of H2S hydrate formation in aqueous solutions of electrolytes and methanol are measured in the temperature range of 272 to 294 K and pressure range of 0.3 to 1.0 MPa. A ‘full view’ sapphire variable volume cell with a movable piston is used to obtain the experimental data.
Characterization of an airlift reactor with helical flow promoters
Authors: Schlötelburg Cord , Popovic Milan , Gluz Michail , Merchuk Jose C. 
Published: March 2009

AbstractThe helical flow promoter (HFP), inserted in the downcomer of an airlift reactor (ALR), generates a helical flow pattern in the circulating gas–liquid (solid) mixture. Data on the fluidization capacity, gas holdup, liquid velocity and mass transfer rate for two‐ and three‐phase systems with two different carboxymethylcellulose solutions collected in a 58 L ALR‐HFP are presented and compared with those of common pneumatic reactors. Generally, an increasing solid concentration led to a slight decrease in gas holdup and liquid velocity but to a considerable decrease in mass transfer rates. Insertion of HFPs produced a significantly enhanced fluidization capacity of solid particles compared to the common systems.
Production of liquid fuels from waste plastics
Authors: Scotp Donald S. , Majerski Piotr , Piskorz Jan , Radlein Desmond , Barnickel Michael 
Published: March 2009

AbstractExploratory work was carried out to develop a process for conversion of mixed plastic wastes into liquid transportation fuels or petrochemicals. The concept used is based on thermal depolymerization of the polymers in a suitable solvent followed by catalytic conversion of the resulting polymeric fragments into hydrocarbons with boiling points below 525°C. The process is carried out batch‐wise over a zeolite catalyst at temperatures from 350°C to 450°C and at atmospheric pressure. No hydrogen is used and volatile products formed are continuously removed from the reactor. Tests were carried out on polyethylene and polypropylene alone, and on mixtures of the two. Finally, a synthetic mixture of four different plastics was tested. From 90% to 98% of the plastic was converted to gases or distillable hydrocarbons. Of this yield, from 20% to 55% was gas, primarily propylenes and butylenes, and from 32% to 70% was a light hydrocarbon oil. Very little non‐distillable coke or residue was formed. The use of mixtures did not affect the high conversions obtained, but the results could only be approximately predicted based on a pro‐rating of results for the individual components.
(Gas‐)liquid‐solid circulating fluidized beds and their potential applications to bioreactor engineering
Authors: Zhu Jing‐Xu (Jesse) , Karamanev Dimitre G. , Bassi Amarjeet S. , Zheng Ying 
Published: March 2009

AbstractCompared with conventional fluidized beds, circulating fluidized beds have many advantages including better interfacial contacting and reduced backmixing (Lim et al., 1995). While there are many reports on the gas—solid circulating fluidized systems, liquid—solid and gas—liquid—solid circulating fluidized bed systems have been scantily studied. However, extending current knowledge obtained in gas—solid systems to liquid—solids and gas—liquid—solid three‐phase systems is shown to open new horizons for applications of circulating fluidized bed technology and expected to lead to the development of highly efficient liquid—solid and gas—liquid—solid reactors, especially for the ever growing field of biotechnology. In order to fully appreciate the potential of those two types of liquid phase circulating fluidized beds, recent progress is reviewed in this article. Their potential applications to biochemical processes are also discussed.
Thermal and catalytic upgrading of a biomass‐derived oil in a dual reaction system
Authors: Srinivas Srimat T. , Dalai Ajay K. , Bakhshi Narendra N. 
Published: March 2009

AbstractThe thermal and catalytic upgrsding of bio‐oil to liquid fuels was studied at atmospheric pressure in a dual reactor system over HZSM‐5, silica‐alumina and a mixed catalyst containing HZSM‐5 and silica‐alumina. This bio‐oil was produced by the rapid thermal processing of the maple wood. In this work, the intent was to improve the catalyst life. Therefore, the first reactor containing no catalyst facilitated thermal cracking of blo‐oil whereas the second reactor containing the desired catalyst upgraded the thermally cracked products. The effects of process variables such as reaction temperature (350°C to 410°C), space velocity (1.8 to 7.2 h−1) and catalyst type on the amounts and quality of organic liquid product (OLP) were investigated, In the case of HZSM‐5 catalyst, the yield of OLP was maximum at 27.2 wt% whereas the selectivity for aromatic hydrocarbons was maximum at 83 wt%. The selectivities towards aromatics and aliphatic hydrocarbons were highest for mixed and silica‐alumina catalysts, respectively. In all catalyst cases, maximum OLP was produced at an optimum reaction temperature of 370°C in both reactors, and at higher space velocity. The gaseous product consisted of CO and CO2, and C1‐C6 hydrocarbons, which amounted to about 20 to 30 wt% of bio‐oil. The catalysts were deactivated due to coking and were regenerated to achieve their original activity.
A new expression of the Ks factor for helical ribbon agitators
Authors: Delaplace Guillaume , Leuliet Jean‐Claude 
Published: March 2009

AbstractThe purpose of this note is to present a new model that is able to predict an effective shear rate in a vessel equipped with helical ribbon agitators, when mixing shear‐thinning fluids. This model is based on well established results obtained for non‐Newtonian flow in cylindrical ducts.
On the validity of the gradient diffusion approach as applied to modelling particle dispersion in a turbulent gaseous flow
Authors: Lightstone Marilyn F. , Raithby George D. 
Published: March 2009

AbstractThis paper develops a criterion for predicting when gradient diffusion should adequately predict the dispersion of particles in simple gaseous turbulent flows such as round jets or the decay region of a grid‐generated turbulent flow. The development of this criterion involves deriving the solution to the gradient diffusion model by another route, where the assumptions required to yield the solution can be carefully considered. This derivation also provides an expression for the particle diffusivity. The model is then applied to two flows where particulate dispersion has been measured experimentally: flow behind a turbulence‐generating grid, and a round jet flow. Under conditions where the criterion for gradient diffusion is satisfied, good agreement is found between measurement and theory.
Model study of the direct causticization reaction between sodium trititanate and sodium carbonate
Authors: Nohlgren Ingrid , Theliander Hans , Zhuang Qianlin , Van Heiningen Adriaan R. P. 
Published: March 2009

AbstractThe solid state reaction between sodium tri‐titanate and sodium carbonate, forming mainly sodium pentatitanate, was investigated. Experiments were carried out in a micro‐differential reactor made of quartz glass at various temperatures between 800°C and 880°C and in a pilot fluidized bed reactor operated in a semi‐batch mode. In the former reactor, basic kinetic data was obtained by measuring the release of carbon dioxide. Different kinetic models were considered to describe the conversion, such as the Valensi‐Carter model for diffusion controlled reaction rates and the phase‐boundary model for first‐order reaction kinetics. Furthermore, a model that included both diffusion in the solid material and the chemical kinetics was derived. This model described the experimental data obtained in the micro‐differential reactor very well. However, for the fluidized bed experiments, these different kinetic models did not accurately describe the experimental data. Therefore, an improved model was developed, which also took into account the time taken for the reactants to achieve physical contact. This model gave good agreement with the experimental data.