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Showing papers in "Canadian Journal of Chemical Engineering in 2000"


Journal ArticleDOI
TL;DR: In this article, the removal of lead, cadmium and zinc from a solution containing the three metals gave a selectivity in the order Zn>Pb>Cd. Predictions of an equilibrium-constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.
Abstract: Sodium-di-(n-octyl) phosphinate (NaL) was used as a precipitating agent to remove heavy metals from aqueous nitrate solutions. Cadmium, zinc and mixtures of lead, cadmium and zinc were precipitated in the form of PbL 2(s) , CdL 2(s) , and ZnL 2(s) . Lowering the pH of the feed solution reduced the removal of the metals as some of the phosphinate precipitated in the acid form as HL (s) . The removal of lead, cadmium, and zinc, from a solution containing the three metals gave a selectivity in the order Zn>Pb>Cd. Predictions of an equilibrium-constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.

186 citations


Journal ArticleDOI
TL;DR: In this paper, the potential applications of these two types of liquid phase circulating fluidized beds are discussed and their potential applications to biochemical processes are also discussed in the field of biotechnologies.
Abstract: Compared 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 Comparativement aux lits fluidises classiques, les lits fluidises circulants offrent de nombreux avantages, dont un meilleur contact interfacial et un retromelange reduit (Lim et al, 1995) Bien qu'un nombre important d'articles paraissent sur les systemes fluidises circulants gaz—solide, les systemes a lits fluidises circulants liquide—solide et gaz—liquide—solide ont fait l'objet de peu d'etudes On montre cependant que l'utilisation des connaissances actuelles sur les systemes gaz—solide pour les etendre aux systemes liquide—solides et aux systemes triphasiques gaz—liquide—solide ouvre de nouveaux horizons a l'application de la technologie du lit fluidise circulant et devrait permettre le developpement de reacteurs liquide—solide et gaz—liquide—solide hautement efficaces, en particulier pour le secteur de la biotechnologie toujours en croissance Afin d'apprecier pleinement le potentiel de ces deux types de lits fluidises circulants en phase liquide, les derniers progres en la matiere sont passes en revue dans cet article Leurs applications potentielles aux procedes biochimiques sont egalement examinees

137 citations


Journal ArticleDOI
TL;DR: In this article, the authors simulate conditions of coal combustion with flue gas recirculation in order to maximize the CO2 concentration in the flue gases prior to its recovery, and the experimental results in terms of flame temperatures and pollutant emissions (NOx, SO2 and CO).
Abstract: As part of CO2 abatement strategies for climate change, we are investigating coal combusion behaviour in various O2/CO2 mixtures and in air. The goal is to simulate conditions of coal combustion with flue gas recirculation in order to maximize the CO2 concentration in the flue gas prior to its recovery. A western Canadian sub-bituminous coal and a U.S. eastern bituminous coal were investigated. Thermal input was set at 0.21 MW with a flue gas oxygen concentration of 5 vol%. Experiments were done using various O2/CO2 mixtures and air. The oxygen concentration ranged from 21% to 42%. Up to 95% CO2 concentrations were achieved in the flue gas. This paper describes experimental results in terms of flame temperatures and pollutant emissions (NOx', SO2 and CO).

133 citations


Journal ArticleDOI
TL;DR: In this paper, a new approach based on the doping of rich estuarine oil sands with calcium and/or clays was developed to study bitumen extraction, which showed that the addition of either calcium ions up to 40 p.p.m., or kaolinite, illite and montmorillonite clays at 1 wt% of oil sands processed had marginal effect on bitumen recovery from the estuarial ores.
Abstract: A novel approach, based on the doping of rich estuarine oil sands with calcium and/or clays, was developed to study bitumen extraction. The batch flotation tests showed that the addition of either calcium ions up to 40 p.p.m., or kaolinite, illite and montmorillonite clays at 1 wt% of oil sands processed had marginal effect on bitumen recovery from the estuarine ores. A sharp reduction in bitumen recovery was observed only when calcium ions greater than 30 p.p.m. and 1 wt% montmorillonite clays were added together. While bitumen recovery correlated well with changes in water/air/bitumen contact angle, no correlation was found between bitumen recovery and measured zeta potential of clays or surface tension of the supernatants from the flotation slurry. The wettability of bitumen was identified as a key element in determining bitumen recovery. The aqueous solution analysis for calcium ions showed that most of the added calcium ions disappeared from the solution when montmorillonite clays were present. The addition of illite or kaolinite clays changed the calcium ion concentration in the slurry only marginally. Stronger adsorption of calcium ions on montmorillonite than on either kaolinite or illite is considered to be responsible for the increased bitumen wettability, and hence reduced bitumen recovery. Une nouvelle methode s'appuyant sur le dopage de sables petroliferes d'estuaires riches avec du calcium et/ou des argiles, a ete mise au point pour etudier I'extraction de bitume. Les essais de flottation discontinus montrent que l'ajout soit d'ions de calcium jusqu'a 40 p.p.m., ou d'argiles de kaolinite, illite et montmorillonite a 1% en poids de sables petroliferes traites a un effet marginal sur la recuperation de bitume de gisements estuariens. On a observe une forte reduction de la recuperation de bitume seulement lorsque des ions de calcium a une concentration superieure a 30 p.p.m. et 1% en poids d'argiles de montmorillonite etaient ajoutes ensemble. Tandis que la recuperation de bitume montre une bonne correlation avec les changements d'angle de contact eau/air/bitume, aucune correlation n'a ete trouvee entre la recuperation de bitume et le potentiel zeta mesure des argiles ou la tension de surface des suranageants de la suspension de flottation. La mouillabilite du bitume est apparue comme un element cle pour determiner la recuperation de bitume. L'analyse de la solution aqueuse pour les ions de calcium montre que la plupart des ions de calcium ajoutes disparaissent de la solution en presence d'argiles de montmorillonite. L'ajout d'argiles d'illite ou de kaolinite ne modifie que marginalement la concentration d'ions de calcium dans la suspension. Une plus forte adsorption des ions de calcium sur la montmorillonite par rapport a la kaolinite ou illite est consideree comme etant responsable de la mouillabilite accrue du bitume, d'ou la moins grande recuperation de bitume.

115 citations


Journal ArticleDOI
TL;DR: In this article, a two-layer model for predicting friction losses for pipeline flows of settling slurries has been extended to solids concentrations above 35% by volume by incorporating new experimental results to account for increases in friction observed with “settling” slurries at high concentrations.
Abstract: The well-known two-layer model for predicting friction losses for pipeline flows of settling slurries has been extended to solids concentrations above 35% by volume. This has been achieved by incorporating new experimental results to account for increases in friction which have been observed with “settling” slurries at high concentrations. The kinetic (fluid-like) friction appears to increase with solids concentration in a manner which suggests that particle-wall contact plays an important role. The experiments also suggest that the fraction of the total solids which contributes Coulombic (velocity insensitive) friction also increases to some extent at high concentrations. This effect is expressed in a tentative correlation which employs a slurry Reynolds number. In addition, new experimental measurements of delivered and in-situ concentrations have been used to test predictions made with the previous version of the model. The measurements show that the interracial friction factor proposed recently by Wilson and coworkers is preferable for slurries of coarse particles. Le modele a deux couches bien connu pour la prediction des pertes par frottement dans les ecoulements des boues de decantation dans les conduites a ete etendu aux concentrations de solides superieures a 35% en volume. Ceci a ete realise en introduisant de nouveaux resultats experimentaux afin de tenir compte des augmentations de frottement qui ont ete observers avec des boues de “decantation” a de fortes concentrations. Le frottement cinetique (semblable a un fluide) semble augmenter avec la concentration de solides d'une facon qui laisse penser que le contact particules-paroi joue un role important. Les experiences semblent egalement montrer que le fraction des solides totaux qui contribue au frottement de Coulomb (insensible a la vitesse) augmente egalement dans une certaine mesure a de fortes concentrations. Cet effet est exprimee dans une correlation provisoire basee sur un nombre de Reynolds des boues. En outre, on a eu recours a de nouvelles mesures experimentales de concentrations indirectes et in situ pour tester les predictions realisees a l'aide de la version precedente du modele. Ces mesures montrent que le facteur de frottement interracial recemment propose par Wilson et ses collegues est preferable pour des suspensions de particules grossieres.

114 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe the development of a novel proximity gauging technique for soft deposits, exploiting a siphon effect, which has the capability to measure the thickness of soft deposits on a surface in situ and in real time.
Abstract: This paper describes the development of a novel proximity gauging technique for soft deposits, exploiting a siphon effect. This non-contact technique has the capability to measure the thickness of soft deposits on a surface in situ and in real time. A theoretical model of performance has been developed and its validity demonstrated by calibration experiments. Local thickness measurements of soft deposits such as whey protein deposit, supermarket butter and sticky foam on metal surfaces had an accuracy of ±20 μm for a deposit thickness of 500 to 1000 μm. The potential of this technique for on-line monitoring of fouling and cleaning processes in liquid environments is demonstrated by preliminary studies of alkali (NaOH) cleaning of whey protein deposits from stainless steel surfaces. On decrit dans cet article la mise au point d'une nouvelle technique de jaugeage de proximite pour des depots mous, exploitant un effet siphon. Cette technique sans contact a la capacite de mesurer l'epaisseur de depots mous sur une surface in situ et en temps reel. Un modele de performance theorique a ete developpe et sa validite est demontree par des experiences de calibration. Des mesures d'epaisseur locales de depots mous tels que des depots de proteines de petit-lait, du beurre de supermarche et de la mousse collante sur des surfaces metalliques ont une precision de ±20 μm pour une epaisseur de depot de 500 a 1000 μm. Le potentiel de cette technique pour la surveillance en continu des precedes de refoulement et de nettoyage dans des environ-nements liquides est demontre par des etudes prelim-inaires de nettoyage a la soude (NaOH) de depots de proteines de petit-lait sur des surfaces d'acier inoxydable.

87 citations


Journal ArticleDOI
TL;DR: In this article, a dual-reactor system over HZSM-5, silica-alumina and a mixed catalyst was used to upgrade bio-oil to liquid fuels.
Abstract: The 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 (18 to 72 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 272 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 On a etudie la transformation thermique et cataly-tique d'huile bioloique en combustibles liuides a la pression atmospherique dans un reacteur double sur un catalyseur HZSM-5, un catalyseur de silice-alumine et un catalyseur mixte contenant du HZSM-5 et de la silice-alumine Cette huile biologique a ete produite par le traitement thermique rapide du bois d'erable Dans ce travail, le but est d'ameliorer la vie du catalyseur Ainsi, le premier reacteur ne contenant aucun catalyseur facilite le crauage thermique de l'huile biologique, tandis que le deuxierne reacteur contenant le catalyseur desire ameliore les produits du craquage thermiue On a etudie les effets des variables de procedes, tels la temperature de reaction de 350°C a 410°C), la vitesse spatiale (de 18 a 72 h−1) et le type de catalyseur, sur la quantite et la qualite de produit liquide organique (OLP) Dans le cas du catalyseur HZSM-5, le rendement en OLP est maximum a 272% en poids, alors que la selectivite pour les hydrocarbures arornatiques est maximum a 83% en poids Les selectivites pour les hydrocarbures arornatiques et alipha-tiques sont les plus grandes pour le cadyseur mixte et le catalyseur de silice-alumine, respectivement Dans tous les cas de catalyseurs, on obtient une production maximum d'OLP a une temperature de reaction optimum de 370°C dans les deux reacteurs, et a une grande vitesse spatiale Le produit gazeux comprend des hydrocarbures de CO et de CO2 et des hydrocarbures C1-C6 qui correspondent a environ 20%-30% de l'huile biologique Les catalyseurs ont ete desactives en raison de la cokefaction et ont ete regeneres afin qu'ils remplissent leur fonction originale

79 citations


Journal ArticleDOI
TL;DR: In this article, the surfaces of BS particles are coated with toluene insoluble organic matter (TIOM), which is polar and aromatic with contributions from both humic and asphaltene-like components, and these surfaces are capable of stabilizing fine water emulsions in the bitumen phase.
Abstract: Bitumen, separated from oil sands by the hot water extraction process, contains ultra-fine (< 200 nm), inorganic solids (BS). Surfaces of BS particles are coated with toluene insoluble organic matter (TIOM). This organic material is polar and aromatic with contributions from both humic and asphaltene-like components. Although the surfaces of BS particles are dominated by TIOM, the coverage is patchy rather than continuous. As a result, these solids are capable of stabilizing fine water emulsions in the bitumen phase. The nature of the organic matter on the surfaces of the particles is such that it has a high propensity to form coke. Therefore, these particles can also play a role in fouling on equipment and catalysts. Le bitume separe des sables petroliferes par le procede d'extraction a air chaud, contient des solides inorganiques (BS) ultrafins (<200 mm). Les surfaces des particules BS sont recouvertes de matiere organique insoluble au toluene (TIOM). Cette matiere organique est polaire et aromatique avec des contributions provenant de composants humiques et proches de l'asphaltene. Bien que les surfaces des particules BS soient dominees par le TIOM, le revetement est irregulier plutot que continu. Par consequent, ces solides sont capables de stabiliser des emulsions aqueuses fines dans la phase du bitume. La nature de la matiere organique sur les surfaces des particules est telle qu'elle a une forte propension a former du coke. Ces particules peuvent donc jouer un role dans l'encrassement des equipements et des catalyseurs.

76 citations


Journal ArticleDOI
TL;DR: In this article, the effect of particle shape on pipeline friction in turbulent flow has been evaluated using laboratory pipelines of nominal diameter 50 mm and 150 mm, and the results indicate that particle-wall contact is the mechanism for the increase in pipeline friction.
Abstract: Experiments have been conducted to assess the effect of particle shape on pipeline friction in turbulent flow, using laboratory pipelines of nominal diameter 50 mm and 150 mm. The experiments were intended to examine the extent to which a fluid model is appropriate for slurries of this type, especially at high solids concentrations. The experiments confirm that fluid friction at low and moderate solids concentrations is proportional to slurry density, with particle shape being of minor importance. At high solids concentrations, additional increases in friction are observed and these depend upon the ratio of the solids concentration to the maximum settled concentration. Although this friction increase is qualitatively similar to that which would result from increased slurry viscosity, the evidence suggests that particle-wall contact is the mechanism. However, the transition from turbulent to laminar flow indicates that an effective viscosity should be used in calculating critical Reynolds numbers. Afin d'evaluer l'effet de la forme des particules sur le frottement dans les pipelines en regime turbulent, des experiences ont ete menees avec des pipelines de laboratoire d'un diametre nominal de 50 mm et de 150 mm. Le but de ces experiences etait de voir jusqu'a quel point un fluide modele est approprie pour ce type de suspensions, en particulier a de fortes concentrations de solides. Les experiences confirment que le frottement du fluide a des concentrations de solides faibles ou moyennes est proportionnel a la masse volumique des suspensions, la forme des particules etant de peu d'importance. A de fortes concentrations de solides, on observe un accroissement supplementaire du frottement qui est lie au rapport entre la concentration de solides et la concentration sedimentee maximum. Bien que cette augmentation du frottement soit d'un point de vue qualitatif semblable a ce qu'il reulterait d'une viscosite accrue des suspensions, selon toutes les apparences le mecanisme reside dans le contact particules-paroi. Cependant, la transition de l'ecoulement turbulent a l'ecoulement laminaire indique qu'une viscosite effective devrait ##etre utilisee dans le calcul des nombres de Reynolds critiques.

75 citations


Journal ArticleDOI
TL;DR: In this paper, Alcell-derived lignin was depolymerized in a batch reactor using the Lewis acid catalysts NiCl2 and FeCl3, achieving 30% and 26% from Ni and Fe, respectively, at reaction conditions of 305°C and 1 h reaction time.
Abstract: Alcell-derived lignin was depolymerized in a batch reactor using the Lewis acid catalysts NiCl2 and FeCl3. The objective was to investigate the use of Lewis acids in the production of useful liquid products directly from solvolysis lignin. The effects of reaction temperature, time and catalyst were studied on the conversion of this lignin to gas, solid and liquid products. Also, selected monomeric compounds in the ether solubles were monitored in terms of the variation in their yields with different reaction conditions. The highest conversions, 30% and 26% from Ni and Fe, respectively, were both attained at the reaction conditions of 305°C and 1 h reaction time. The Ni produced a somewhat higher yield of ether solubles, reflecting its slightly higher performance. Under the reaction conditions studied, both catalysts apparently favour condensation reactions leading to the formation of insoluble reactor residue from solvolysis lignin. Low quantities of monomeric compounds were produced, with phenols dominating over ketones and aldehydes for both catalysts. De la lignine obtenue par le procede Alcell a ete depolymerisee dans un reacteur discontinu a l'aide de catalyseurs acides de Lewis NiCl2 et FeCl2. L'objectif etait d'etudier l'utilisation des acides de Lewis dans la production de produits liquides utiles directement a partir de la lignine de solvolyse. On a etudie les effets de la temperature de reaction, du temps de reaction et du catalyseur sur la conversion de cette lignine en produits gazeux, solides et liquides. En outre, on a suivi la variation du rendement de composes monomeres selectionnes dans les solubles ethers dans differentes conditions de reaction. Les plus fortes conversions, soient 30% et 26% du Ni et du Fe respectivement, etaient dans les deux cas reliees aux conditions de reaction, soient une temperature de 305°C et un temps de reaction de 1 heure. Le Ni produit un rendement de solubles ethers un peu plus eleve, refletant sa performance sensiblement meilleure. Dans les conditions de reaction etudiees, les deux catalyseurs favorisent des reactions de condensation, ce qui mene a la formation de residus de reacteur insolubles a partir de la lignine de solvolyse. De faibles quantites de composes monomeres ont ete produites, les phenols dominant les cetones et aldehydes pour les deux catalyseurs.

64 citations


Journal ArticleDOI
TL;DR: In this article, the caracteristiques of coprecipitation of CaCO3 and CaSO4 were studied under various operating conditions, and the relationship between the thermodynamic concentrations of Ca for pure Ca CO3 and caSO4 solutions depended on the pH of the Ca CO 3 solution.
Abstract: Coprecipitation characteristics of CaCO3 and CaSO4 were studied under various operating conditions. The investigations were carried out in temperature-controlled batch tests. Coprecipitation results were compared with our experimental results of a single salt crystallization. It was found that the induction period and kinetics of coprecipitation of these two salts follow that of pure CaCO3. However, thermodynamic concentrations of Ca in coprecipitation followed that of pure CaSO4 at all times. The relationship between the thermodynamic concentrations of Ca for pure CaCO3 and CaSO4 solutions depended on the pH of the CaCO3 solution. CaSO4 precipitated in form of gypsum and had a needle shape structure; CaCO3 had a spiral growth and precipitated in form of calcite. The precipitate structure was affected by the co-existence of salts; the co-precipitation resulted in CaCO3 crystals interwoven by CaSO4 crystals. This tends to result in a co-precipitate that is stronger than pure CaSO4 and weaker than pure CaCO3 precipitate. On a etudie les caracteristiques de coprecipitation du CaCO3 et du CaSO4 dans diverses conditions de fonctionnement. Les etudes ont ete realisees au moyen d'essais discontinus a temperature contrǒlee. Les resultats de coprecipitation ont ete compares a nos resultats experimentaux portant sur la cristallisation d'un sel unique. II s'avere que la periode d'induction et la cinetique de coprecipitation de deux sels suivent celle du CaCO3 pur. Cependant, les concentrations thermodynamiques du Ca en coprecipitation suivent celles du CaSO4 pur en tout temps. La relation entre les concentrations thermodynamiques du Ca pour des solutions de CaCO3 et CaSO4 purs depend du pH de la solution de CaCO3. Le CaSO4 se precipite sous forme de gypse et a une structure en forme d'aiguille; le CaCO3 a une croissance en spirale et se precipite sous forme de calcite. La structure du precipitat est influencee par la coexistence des sels; la coprecipitation donne des cristaux de CaCO3 entrelaces de cristaux de CaSO4. Cela tend a produire un coprecipitat plus fort qu'un precipitat de CaSO3 pur et plus faible qu'un precipitat de CaCO3 pur.

Journal ArticleDOI
TL;DR: In this paper, detailed hydodynamic measurements have been obtained for fully cylindrical spout-fluid beds of 1.3 mm, 1.8 mm, and 2.5 mm glass beads in a column of diameter 152 mm using three different types of optical fibre probes.
Abstract: Detailed hydodynamic measurements have been obtained for fully cylindrical spout-fluid beds of 1.3 mm, 1.8 mm and 2.5 mm glass beads in a fully cylindrical column of diameter 152 mm using three different types of optical fibre probes. The reallocation of up to 43% of the air to auxiliary air introduced through the conical base caused some decrease in spout voidages, but remarkably little change in spout diameter compared with spouted beds where there was no auxiliary air addition. Auxiliary air led also to some decrease in particle velocities in the spout and to a modest decrease in the net solids circulation rate.

Journal ArticleDOI
TL;DR: In this article, a 4-environment generalized micromixing (4-EGM) model is applied to describe turbulent mixing and precipitation of barium sulfate in a tubular reactor.
Abstract: The 4-environment generalized micromixing (4-EGM) model is applied to describe turbulent mixing and precipitation of barium sulfate in a tubular reactor. The model is implemented in the commercial computational fluid dynamics (CFD) software Fluent. The CFD code is first used to solve for the hydrodynamic fields (velocity, turbulence kinetic energy, turbulent energy dissipation). The species concentrations and moments of the crystal size distribution (CSD) are then computed using user-defined transport equations. CFD simulations are performed for the tubular reactor used in an earlier experimental study of barium sulfate precipitation. The 4-EGM CFD results are shown to compare favourably to CFD results found using the presumed beta PDF model. The latter has previously been shown to yield good agreement with experimental data for the mean crystal size at the outlet of the tubular reactor. On a applique un modele de micromelange generalise a 4 environnements (4-EGM) afin de decrire le melange turbulent et la precipitation du sulfate de baryum dans un reacteur tubulaire. Ce modele a ete implante dans le logiciel de CFD commercial Fluent. Le programme de CFD est d'abord utilise pour calculer les champs hydrodynamiques (vitesse, energie cinetique de turbulence, dissipation d'energie turbulente). Les concentrations d'especes et les moments de la distribution de taille des cristaux (CSD) sont ensuite calcules par ordinateur a l'aide des equations de transport definies par l'usager. Des simulations de CFD sont realisees pour le reacteur tubulaire utilise dans une etude experimentale anterieure de la precipitation du sulfate de baryum. On montre que les predictions du 4-EGM se comparent favorablement a celles du modele beta PDF. II a ete montre anterieurement que ce dernier presentait un bon accord avec les donnes experimentales pour la taille moyenne des cristaux a la sortie du recteur tubulaire.

Journal ArticleDOI
TL;DR: In this paper, both new and previously published deposition velocity data for aqueous Newtonian slurries are incorporated in a correlation which complements the earlier predictions of Durand, Wilson and A.D. Thomas.
Abstract: In this contribution both new and previously published deposition velocity data for aqueous Newtonian slurries are incorporated in a correlation which complements the earlier predictions of Durand, Wilson and A.D. Thomas. Most of the new data has been obtained for slurries of narrowly sized sand particles of median diameter ranging between 90 and 420 μm, in pipes of diameter between 0.05 and 0.5 m. The data were obtained in laboratory investigations under isothermal flow conditions. Dans ce travail de contribution, de nouvelles donnees et des donnees publiees anterieurement sur la vitesse de deposition de suspensions newtoniennes aqueuses sont introduites dans une correlation qui vient completer les predictions anterieures de Durand, Wilson et A.D. Thomas. La plupart des nouvelles donnees ont ete obtenues pour des suspensions de particules de sable presque monodisperses dont le diametre varie entre 90 et 420 μm, dans des conduites d'un diametre compris entre 0,05 et 0,5 m. Ces donnees ont ete obtenues lors de recherches en laboratoire dans des conditions d'ecoulement isothermes.

Journal ArticleDOI
TL;DR: In this article, the authors examined the impingement of axisymmetric jets in a confined space using flow visualization, laser Doppler anemometry, and numerical simulations.
Abstract: The flow of jets in confining enclosures has significant application in many engineering processes. In particular, the impingement of axisymmetric jets in a confined space has been examined using flow visualization, laser Doppler anemometry, and numerical simulations. Several flow regions were found; stable steady, regular oscillatory, and irregular oscillatory. Initially, a steady flow field existed for all arrangements for Red < ˜90 (based on the nozzle diameter d, the fluid kinematic viscosity v and the volumetric flow rate Q through the nozzle (Q = πd2/4Uavg)) but subsequent increments in the fluid velocity caused a regularly oscillating flow field to emerge. The onset of the oscillations and the upper limit of finite oscillations were found to be a function of the Red, and the nozzle diameter to chamber dimension ratio. Steady numerical simulations predicted the steady flow field well and good agreement was obtained in unsteady simulations of the oscillating flow field. The oscillating flow field is considered to be a class of self-sustaining oscillations where instabilities in the jet shear layer are amplified because of feed back from pressure disturbances in the impingement region. L'ecoulement de jets dans des espaces confines a des applications importantes dans de nombreux precedes d'ingenierie. On a examine en particulier la collision de jets axisymetriques dans un espace confine au moyen de la visualisation des ecoulements, de l'anemometrie par laser Doppler et de simulations numeriques. On a trouve plusieurs regions d'ecoulement : stable-stationnaire, regulier-oscillatoire et irregulier-oscillatoire. Initialement, il existe un champ d'ecoulement stationnaire pour toutes les configurations lorsque Red < ˜90 (base sur le diametre de tuyere d, la viscosite cinematique du fluide (et le debit volumetrique Q dans la tuyere (Q = πd24Uavg)); mais une augmentation subsequente de la vitesse du fluide declenche un champ d'ecoulement oscillatoire regulier. On a trouve que l'apparition des oscillations et la limite superieure des oscillations finies sont fonction de Red et du rapport entre le diametre de l'orifice et la dimension de la chambre. Des simulations numeriques stationnaires predisent bien le champ d'ecoulement stationnaire et un bon accord est obtenu pour des simulations non stationnaires du champ d'ecoulement oscillant. Le champ d'ecoulement oscillant est considere etre une categorie d'oscillations qui se maintiennent seules dans laquelle les instabilites dans la couche de cisaillement des jets sont amplifies par un effet retour des perturbations de pression dans la region de collision.

Journal ArticleDOI
TL;DR: In this article, a continuous protein recovery process using a Liquid-Solid Circulating Fluidized Bed (LSCFB) ion exchange system is described and a model with known kinetics has been developed.
Abstract: In this study, a continuous protein recovery process using a Liquid–Solid Circulating Fluidized Bed (LSCFB) ion exchange system is described and a model with known kinetics has been developed. Experiments and computer simulations using Matlab™ are conducted at different operating conditions. The effects of hydro-dynamic parameters and kinetic parameters on the performance of the LSCFB ion exchange system are discussed. The model is shown to be applicable for the design of LSCFB ion exchange systems for protein recovery. On decrit dans cette etude un procede de recuperation de proteines continu utilisant un systeme d'echange d'ions a lit fluidise circulant liquide-solide (LSCFB) ainsi qu'un modele base sur une cinetique connue. Des experiences et des simulations par ordinateur a l'aide de Matlab™ sont menees pour differentes conditions de fonctionnement. Les effets des parametres hydrodynamiques et des parametres cinetiques sur la performance du systeme d'echange d'ions LSCFB sont analyses. On montre que le modele est applicable a la conception de systemes d'echange d'ions LSCFB pour la recuperation de proteines.

Journal ArticleDOI
TL;DR: In this article, a tentative flow regime boundary between the regions of intermittent and continuous water-assisted flow is proposed in terms of the mixture Froude number and the injected water fraction.
Abstract: Experimental simulations of model well-bore flows in laboratory pipelines show that frictional energy losses (i.e., pressure drops) are reduced when water is present with heavy oil. The reduction has been shown to increase with the water fraction. The mixtures are not oil in water emulsions in the classical sense of the term. At the low axial velocities which characterize wellbore flows, the flow regime is inherently intermittent. Using a variety of methods the structure of the flow has been examined to identify the flow regime and the cause of the reduced pressure gradients. It has been found that the water travels as large slugs and that oil is invariably present at the wall when the mixture flows through a steel pipe. The evidence suggests that a significant fraction of the oil is transported within the water slugs. A tentative flow regime boundary between the regions of intermittent and continuous water-assisted flow is proposed in terms of the mixture Froude number and the injected water fraction. Des simulations experimentales d'ecoulements dans des puits de forage modeles de laboratoire montrent que les pertes d'energie par frottement (p.ex., pertes de charge) sont reduites lorsqu'il y a de l'eau dans l'huile lourde. On montre que cette reduction est plus grande avec l'augmentation de la fraction d'eau. Les melanges ne sont pas des emulsions d'huile dans l'eau au sens classique du terme. A de faibles vitesses axiales qui caracterisent les ecoulements de puits de forage, le regime d'ecoulement est fondamentalement intermittent. A l'aide de diverses methodes, la structure de l'ecoulement a ete examinee afin de determiner le regime d'ecoulement et la cause de la reduction des gradients de pression. On a trouve que l'eau se deplacait sous forme de gros bouchons et que l'huile etait invariablement presente a la paroi quand le melange s'ecoule dans une conduite d'acier. II apparait qu'une fraction significative de l'huile est transported au sein des bouchons d'eau. Une limite de regime d'ecoulement entre les regions de l'ecoulement intermittent et l'ecoulement assiste par l'eau continu est proposee provisoirement en fonction du nombre de Froude du melange et de la fraction d'eau injectee.

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TL;DR: In this paper, a phenomenological-based FCC model is presented for steady and unsteady state simulation of FCC units, which accounts for the behavior of the riser, the stripper and the regenerator.
Abstract: A FCC phenomenological-based model is presented in this study. This model accounts for the behaviour of the riser, the stripper and the regenerator. Both the reactor and the regenerator are incorporated in the model using detailed reaction kinetics. Catalyst regeneration allows for both catalytic and non-catalyzed combustion of CO to CO2. Overall, the model is constituted by a set of ordinary differential equations, relatively easy to solve and suitable for steady and unsteady state simulation of FCC units. The proposed model avoids, as much as possible, empirical expressions being suitable for simulation of industrial FCC units and process control studies. Un modele phenomenologique de FCC est presente dans cette etude. Ce modele tient compte du comportement de la colonne montante, de la colonne de fractionnement et du regenerateur. Le reacteur et le regenerateur sont tous deux introduits dans le modele en utilisant une cinetique de reaction detaillee. La regeneration du catalyseur permet la combustion catalytique et non catalysee de CO en CO2. De facon generate, le modele comprend un ensemble d'equations differentielles ordinaires, qui sont relativement faciles a resoudre et qui sont adaptees a la simulation en regime permanent et non permanent de systemes FCC. Le modele propose evite dans la mesure du possible les expressions empiriques destinees aux etudes de simulation de systemes FCC industriels et de regulation de procedes.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the control of crystal size distribution in a 1.5 L laboratory cooling KCl crystallizer using fines dissolution rate as the manipulated variable and showed that effective control of mean crystal size and fines suspension density in the presence of setpoint and disturbance changes is feasible with both control schemes.
Abstract: The control of crystal size distribution (CSD) is investigated in a 1.5 L laboratory cooling KCl crystallizer using fines dissolution rate as the manipulated variable. The controlled variable was either the fines suspension density in the fines withdrawal loop, measured by an innovative double-sensor turbidity meter manufactured in-house, or the chord length distribution (CLD) measured by the Focused Beam Reflectance Measurement (FBRM®) probe (model: Par-Tec® 100, Lasentec®, Redmond, WA). It was shown that effective control of mean crystal size and fines suspension density in the presence of setpoint and disturbance changes is feasible with both control schemes. The double sensor turbidity sensor proved to be very rugged even in the presence of insoluble clay background particles. The FBRM® probe was more sensitive and capable of detecting particle breakage and flocculation. On a etudie le controle de la distribution de taille des cristaux (CSD) dans un cristallisoir de KCl refroidi de laboratoire de 1,5 L en utilisant la vitesse de dissolution des fines comme variable manipulee. La variable controlee etait soit la densite de suspension des fines dans la boucle de retrait des fines, mesuree par un turbidimetre a double capteur novateur fabrique par nos soins, soit la distribution de longueur de corde (CLD) mesuree par une sonde FBRM® (mesure de la reflectance des faisceaux focalises) (modele : Par-Tec® 100, Lasentec®, Redmond, WA). On a montre que le controle effectif de la taille moyenne des cristaux et de la densite de suspension des fines en presence de changements de consignes et de perturbations est realisable avec les deux Schemas de controle. Le turbidimetre a double capteur s'est avere tres robuste meme en presence de particules d'argile insolubles. La sonde FBRM® est plus sensible et est capable de detecter la rupture et la floculation des particules.

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TL;DR: In this paper, a membrane technique to treat olive oil mill washing water using different commercial ultrafiltration membranes: one organic (PCI) and two ceramic (Ceraver) membranes was evaluated, and it was shown the organic PCI membrane could reduce pollution due to organic matter by decreasing the value of the Chemical oxygen demand by about 90%.
Abstract: Olive oil production requires important quantities of washing water containing low oil concentrations, but classical processes used to recover or to eliminate this oil are ineffective. This study presents a membrane technique to treat olive oil mill washing water using different commercial ultrafiltration membranes: one organic (PCI) and two ceramic (Ceraver) membranes. The influence of the hydrodynamic parameters (transmembrane pressure and flow rate) and the cut-off membranes on the efficiency of the ultrafiltration process was evaluated, and it was shown the organic PCI membrane could reduce pollution due to organic matter by decreasing the value of the Chemical oxygen demand by about 90%. Moreover, the nature of the ultrafine pore membrane appeared to be an important parameter which may strongly increase or decrease the capacity of the membrane. The membrane cut-off did not have a strong influence on the performance of the process but if the membrane pores were too large the stability of the dynamically formed membrane decreased at transmembrane pressures greater than 0.2 MPa. La production d'huile d'olive requiert des quantites importantes d'eau de lavage contenant de faibles concentrations d'huile, mais les procedes classiques utilises pour recuperer ou eliminer cette huile sont inefficaces. On presente dans cette etude une technique membranaire pour le traitement de l'eau de lavage d'une unite de fabrication d'huile d'olive dans laquelle differentes membranes d'ultrafiltration commerciales sont employees: une membrane organique (PCI) et deux membranes de ceramique (Ceraver). L'influence des parametres hydrodynamiques (pression et debit transmembranaires) et de la distribution de taille des pores sur l'efficacite du procedee d'ultrafiltration a ete evaluee, et on montre que la membrane organique PCI pourrait reduire la pollution due a la matiere organique en diminuant la valeur de la demande chimique en oxygene d'environ 90%. Par ailleurs, la nature de la membrane a pores ultrafines semble un parametre important qui pourrait fortement augmenter ou diminuer la capacite de la membrane. La taille des pores n'exerce pas une grande influence sur la performance du procede mais si les pores de membrane sont larges, la stabilkite de la membrane formee de maniere dynamique diminue a des pressions transmembranaires superieures a 0,2 MPa.

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TL;DR: In this article, the linear viscoelastic properties of one family of base asphalts, unmodified or modified by the simple addition of an elastomer or by further in-situ crosslinking, have been investigated.
Abstract: The linear viscoelastic properties of one family of base asphalts, unmodified or modified by the simple addition of an elastomer or by further in-situ crosslinking, have been investigated. The time-temperature superposition principle was shown to be valid for the base as well as for the modified asphalts. The addition of the elastomer styrene-butadiene (SB) copolymer increased drastically the storage modulus and the elastic character of the asphalts. The thermal susceptibility of the polymer modified asphalts was considerably reduced and this combined with an increased resistance to deformation (larger complex modulus) suggests much better performances for road applications. The chemically modified asphalt containing 3% SB showed similar viscoelastic properties as the physical blend containing 6% SB. On a etudie les proprietes viscoelastiques lineaires d'une famille d'asphaltes de base, non modifies ou modifies par simple ajout d'un elastomere ou par reticulation in situ. On montre que le principe de superposition temps-temperature est valable autant pour les asphaltes de base que pour les asphaltes modifies. L'ajout du copolymere elastomere de styrene-butadiene (SB) augmente considerablement le module d'emmagasinage et le caractere elastique des asphaltes. La susceptibilite thermique des asphaltes modifies est grandement reduite ce qui, si l'on tient compte egalement de la resistance accrue a la deformation (module complexe plus grand), suggere de meilleures performances en vue d'applications sur les routes. L'asphalte modifie chimiquement contenant 3% de SB montre des proprietes elastiques comparables au melange physique contenant 6% de SB.

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TL;DR: In this article, the authors reported on the liquid phase adsorption of flavour esters onto granular activated carbon and employed the Dubinin-Radushkevich equation to determine the limiting volume of the adsorbed space.
Abstract: This article reports on the liquid phase adsorption of flavour esters onto granular activated carbon. Ethyl propionate, ethyl butyrate, and ethyl isovalerate were used as adsorbates, and Filtrasorb 400 activated carbon was chosen as the adsorbent. Sips, Toth, Unilan, and Dubinin-Radushkevich isotherm equations which are generally used for heterogeneous adsorbents were used to fit the data. Although satisfactory in fitting the data, inconsistency in parameter values indicated these models to be inadequate. On the other hand the Dubinin-Radushkevich model gave more consistent and meaningful parameter values and adsorption capacities. By employing the Dubinin-Radushkevich equation, the limiting volume of the adsorbed space, which equals the accessible micropore volume, was determined, and found to correlate with the value from carbon dioxide adsorption.

Journal ArticleDOI
TL;DR: In this article, the measurements of liquid flow distribution in a large scale column packed with 25.4 mm stainless steel Pall rings were studied, and two different liquid distributors were employed to test the effect of liquid distributor design.
Abstract: Liquid flow distribution has been a major concern when scaling up random packed columns. This study concerns the measurements of liquid flow distribution in a large scale column packed with 25.4 mm stainless steel Pall rings. The liquid flow distribution was studied with packed bed height from 0.9 to 3.5 m, liquid flow rate from 2.91 to 6.66 kg/m2·s, and gas flow rate from 0 to 3.0 kg/m2·s. In addition, three systems, water/air, aqueous detergent solution/air and Isopar/air, were used to study the effect of liquid physical properties on liquid flow distribution, and two different liquid distributors were employed to test the effect of liquid distributor design. It was found that liquid flow distribution was strongly influenced by liquid distributor design, packed bed height, gas flow rate and liquid viscosity, slightly influenced by liquid flow rate, but not by liquid surface tension. La distribution de l'ecoulement liquide pose un probleme important pour la mise a l'echelle des colonnes garnies aleatoirement. Cette etude porte sur des mesures de distribution d'ecoulement liquide dans une colonne de grande echelle garnie d'anneaux Pall en acier inoxydable de 25,4 mm de diametre. La distribution de l'ecoulement liquide a ete etudiee pour une hauteur de lit garni entre 0,9 et 3,5 m, un debit liquide entre 2,91 et 6,66 kg/m2·s et un debit de gaz entre 0 et 3,0 kg/m2·s. En outre, on a eu recours a trois systemes, soient eau/air, solution a base de detergent aqueuse/air et Isopar/air, pour etudier l'effet des proprietes physiques du liquide sur la distribution de l'ecoulement liquide, et deux distributeurs de liquide differents ont ete utilises afin de tester l'effet de la conception du distributeur de liquide. On a trouve que la distribution de l'ecoulement liquide etait fortement influencee par la conception du distributeur de liquide, la hauteur de lit garni, le debit de gaz et la viscosite du liquide, etait peu influencee par le debit du liquide, et n'etait pas influencee par la tension de surface du liquide.

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TL;DR: In this paper, the effects of surface energy and surface roughness on the deposition of calcium sulphate during convective and subcooled flow boiling heat transfer to aqueous CaSO4 solutions are studied.
Abstract: In this paper the effects of surface energy and surface roughness on the deposition of calcium sulphate during convective and subcooled flow boiling heat transfer to aqueous CaSO4 solutions are studied. The surfaces of several test heaters have been treated by Ion Beam Implantation, Unbalanced Magnetron Sputtering, Mixed Sputtering and Plasma Arc Deposition to reduce surface energy. One heater was electropolished to reduce surface roughness and one heater was etched by an electrochemical method to increase surface roughness. Fouling runs with these heaters, and with an untreated surface as control, were carried out at different heat fluxes, flow velocities and salt concentrations. The results show that heat transfer surfaces with low surface energy experienced significantly reduced fouling, while electropolishing did not have a notable beneficial effect. The combined effect of reduced surface energy and flow velocity on fouling reduction is considerably stronger than previously reported for pool boiling. Dans cet article, on etudie les effets de l'energie de surface et de la rugosite de la surface sur la deposition de sulfate de calcium lors du transfert de chaleur par ebullition convectif et sous-refroidi dans des solutions aqueuses de CaSO4. Les surfaces de sept systemes-tests de chauffage ont ete traitees par “ion beam implantation”, “unbalaced magnetron sputtering”, “mixed sputtering” et par deposition par arc a plasma afin de reduire l'energie de surface. Un systeme de chauffage a ete electropoli pour reduire la rugosite de la surface et un autre systeme a ete grave par une methode electrochimique pour accroǐtre la rugosite de la surface. Des essals d'encrassement de ces systemes, une surface non traitee etant utilisee comme temoin, ont ete menes pour differents flux de chaleur, vitesses d'ecoulement et concentrations de sel. Les resultats montrent que les surfaces de transfert de chaleur a faible energie de surface subissent un encrassement, tandis que l'electropolissage n'a pas d'effet benefique notable. L'effet combine d'une energie de surface et d'une vitesse d'ecoulement reduites sur la reduction du refoulement est considerablement superieur a ce qui a ete mentionne anterieurement pour l'ebullition en bassin.

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TL;DR: In this paper, the authors used both UNIFAC and Modified UNAC (Dortmund) models to estimate the activity coefficient of anthracene in 43 organic solvents, fluoranthene and pyrene.
Abstract: The solubility of anthracene in 43 organic solvents, fluoranthene (45 solvents) and pyrene (30 solvents) has been calculated using UNIFAC and Modified UNIFAC (Dortmund) models to estimate the activity coefficient of the solute. It was found that both UNIFAC and Modified UNIFAC described better the solubilities in polar solvents like alcohols, ketones, esters and ethers than in nonpolar solvents like alkanes and aromatic hydrocarbons. UNIFAC and the Mobile Order Theory supplement each other well in calculating the solubilities, which means that one can choose the right model depending on the solvent one is using.

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TL;DR: In this article, the deposition of magnetite particles from suspension in water at nominally 90°C onto Alloy-800 surfaces has been studied by chemical and radiotracing techniques under various conditions of flow, chemistry and boiling heat transfer.
Abstract: The deposition of magnetite particles from suspension in water at nominally 90°C onto Alloy-800 surfaces has been studied by chemical and radiotracing techniques under various conditions of flow, chemistry and boiling heat transfer. The experiments indicated that, under non-boiling conditions, mechanisms based on diffusion and thermophoresis control deposition while removal is negligible. For sub-cooled boiling at a low rate, the trapping of particles by bubbles is important; at a high rate, deposition during micro-layer evaporation dominates. Removal occurs during sub-cooled boiling and is nicely described by a mathematical model in which it proceeds concomitantly with deposition. La deposition de particules de magnetites en suspension dans l'eau a une temperature nominale de 90°C sur des surfaces d'Alliage-800 a ete etudiee par des techniques chimiques et de radio-tracage dans des conditions d'ecoulement, de chimie et de transfert de chaleur par ebullition variees. Les experiences indiquent que dans des conditions de non ebullition, les mecanismes bases sur la diffusion et la thermophorese contrǒle la deposition tandis que le retrait est negligeable. Pour l'ebullition sous-refroidie a une faible vitesse, la saisie des particules par les bulles est importante; a une vitesse elevee, la deposition pendant l'evaporation de la micro-couche domine. Le retrait se produit lors de l'ebullition sous-refroidie et est bien decrit par un modele mathematique faisant intervenir de facon concomitante le retrait et la deposition.

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TL;DR: In this article, the effects of ice growth rate, solution velocity and bulk concentration of solute on the solute inclusion in the ice layer have been investigated using a controlled flow surface crystallizer (CFSC).
Abstract: Solute inclusion in an ice layer formed on a smooth stainless steel surface under sub-cooled flow conditions has been studied experimentally. The effects of ice growth rate, solution velocity and bulk concentration of solute on the solute inclusion in the ice layer have been investigated using a controlled flow surface crystallizer (CFSC). For several aqueous solutions (sucrose, NaCI, glycol, fructose), food liquids (skim milk, whole milk, orange juice) and particulate suspension (potato starch particles), the effective molecular weights were calculated and their effects on solid inclusion determined. This effect was then conveniently related to the freezing point depression (FPD) of each liquid tested. A generalized empirical correlation has been established for all the liquids tested. On a etudie de maniere experimentale l'inclusion de solute dans une couche de glace formee sur une surface d'acier lnoxydable lisse dans des conditions d'ecoulement sous-refroidies. Les effets de la vitesse de croissance de la glace, de la vitesse de la solution et de la concentration en masse du solute sur l'introduc-tion de solute dans la couche de glace ont ete etudies a l'aide d'un cristallisoir a surface d'ecoulement controle (CFSC). Pour plusieurs solutions aqueuses (sucrose, NaCI, glycol, fructose), liquides alimentaires (lait ecrerne, lait entier, jus d'orange) et une suspension de particules (particules d'amidon de pomme de terre), on a calcule les poids moleculaires effectifs et determine leurs effets sur l'introduction de solides. Cet effet est par la suite facilement relie a la depression du point de congelation (FPD) de chaque liquide teste Une correlation empirique generalisee a ete etablie pour tous les liquides testes.

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TL;DR: In this article, the authors measured the activity coefficients of individual ions at 298.2 K in aqueous solutions of KF, KBr and NaF up to 3, 2 and 1 molal, respectively.
Abstract: Ion selective electrodes were used to measure the activity coefficients of individual ions at 298.2 K in aqueous solutions of KF, KBr and NaF up to 3, 2 and 1 molal, respectively. The mean ionic activity coefficients of the electrolytes obtained from the values of individual ions show good agreement with values reported in the literature. The experimental results confirm that the activity coefficients are different for the anion and the cation in an aqueous solution of a single electrolyte. It is also confirmed that the deviation from ideality for each ion depends on its counterion. The Khoshkbarchi—Vera equation was used to correlate the experimental data. On a utilise des electrodes selectives aux ions afin de mesurer les coefficients d'activite d'ions individuels a 298,2 K dans des solutions aqueuses de KF, KBr et NaF jusqu'a 3, 2 et 1 molals, respectivement. Les coefficients d'activite ionique moyens des electrolytes obtenus a partir des valeurs des ions individuels montrent un bon accord avec les valeurs indiquees dans la litterature scientifique. Les resultats experimentaux confirment que les coefficients d'activite sont differents pour l'anion et le cation dans une solution aqueuse d'une simple electrolyte. Les resultats confirment egalement que l'ecart avec l'idealite de chaque ion depend de son contre-ion. On s'est servi de l'equation de Khoshkbarchi et Vera pour correler les donnees experimentales.

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TL;DR: In this paper, the authors investigate the flow of water-heavy oil mixtures at velocities typical of oil-field gathering systems and show that continuous water assisted flow at very low pressure gradients can be achieved.
Abstract: Experimental investigations of the flow of water-heavy oil mixtures at velocities typical of oil-field gathering systems show that continuous water assisted flow at very low pressure gradients can be achieved. The principal criterion to be satisfied in establishing this desirable flow regime appears to be use of sufficient water, with the velocity also playing a role. It also appears that oil viscosity and water fraction effects on pressure gradient are small provided the beneficial flow regime is established. The flows resemble core-annular flow, which has been observed previously in Bitumen froth and water-heavy oil flows, with an oil layer on the pipe wall. However, the correlation for pressure gradient is somewhat different from that reported previously for Bitumen froth flows.

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TL;DR: In this paper, a model is developed for estimation of the large bubble gas hold-up by introducing an wake-acceleration factor into the Davies-Taylor-Collins relation, describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble.
Abstract: The hydrodynamics of bubble columns with concentrated slurries of paraffin oil (density, ρL = 790 kg/m3; viscosity, μL = 0.0029 Pa·s; surface tension, σ = 0.028 N·m1) containing silica particles (mean particle diameter dp = 38 μm) has been studied in columns of three different diameters, 0.1, 0.19 and 0.38 m. With increasing particle concentration, the total gas hold-up decreases significantly. This decrease is primarily caused by the destruction of the small bubble population. The hold-up of large bubbles is practically independent of the slurry concentration. The measured gas hold-up with the 36% v paraffin oil slurry shows remarkable agreement with the corresponding data obtained with Tellus oil (ρL = 862 kg/m3; μL = 0.075 Pa·s; σ = 0.028 N·m−1) as the liquid phase. Dynamic gas disengagement experiments confirm that the gas dispersion in Tellus oil also consists predominantly of large bubbles. The large bubble hold-up is found to decrease significantly with increasing column diameter. A model is developed for estimation of the large bubble gas hold-up by introduction of an wake-acceleration factor into the Davies-Taylor-Collins relation (Collins, 1967), describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble.