References of "Crine, Michel"
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See detailConvective drying of wastewater sludge: Introduction of shrinkage effect in mathematical modeling
Bennamoun, Lyes ULg; Crine, Michel ULg; Léonard, Angélique ULg

in Drying Technology (2013), 31(6), 643-654

Drying of two kinds of wastewater sludge was studied. The first part was an experimental work done in a discontinuous cross-flow convective dryer using 1 kg of wet material extruded in 12-mm-diameter ... [more ▼]

Drying of two kinds of wastewater sludge was studied. The first part was an experimental work done in a discontinuous cross-flow convective dryer using 1 kg of wet material extruded in 12-mm-diameter cylinders. The results show the influence of drying air temperature for both sludges. The second part consisted of developing a drying model in order to identify the internal diffusion coefficient and the convective mass transfer coefficient from the experimental data. A comparison between fitted drying curves, well represented by Newton's model, and the analytical solutions of the equation of diffusion, applied to a finite cylinder, was made. Variations in the physical parameters, such as the mass, density, and volume of the dried product, were calculated. This allowed us to confirm that shrinkage, which is an important parameter during wastewater sludge drying, must be taken into account. The results showed that both the internal diffusion coefficient and convective mass transfer coefficient were affected by the air temperature and the origin of the sludge. The values of the diffusion coefficient changed from 42.35 × 10−9 m2 · s−1 at 160°C to 32.49 × 10−9 m2 · s−1 at 122°C for sludge A and from 33.40 × 10−9 m2 · s−1 at 140°C to 28.45 × 10−9 m2 · s−1 at 120°C for sludge B. The convective mass transfer coefficient changed from 4.52 × 10−7 m · s−1 at 158°C to 3.33 × 10−7 m · s−1 at 122°C for sludge A and from 3.44 × 10−7 m · s−1 at 140°C to 2.84 × 10−7 m2 · s−1 at 120°C for sludge B. The temperature dependency of the two coefficients was expressed using an Arrhenius-type equation and related parameters were deduced. Finally, the study showed that neglecting shrinkage phenomena resulted in an overestimation that can attain and exceed 30% for the two coefficients. [less ▲]

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See detailCFD Modelisation of homogeneous distribution of solid particles in a stirred tank
Calvo, Sébastien ULg; Delafosse, Angélique ULg; Collignon, Marie-Laure ULg et al

Poster (2013, April 24)

In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a torospherical bottom shaped stirred tank reactor of 70L equipped with ... [more ▼]

In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a torospherical bottom shaped stirred tank reactor of 70L equipped with a Pfaudler RCI type impeller and three equi-spaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is afterward used to developed scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. The 3D geometry of the tank and the associated mesh are respectively realized by Ansys 14 DesignModeler and Meshing. The Sliding-Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics may be simulated independently using the well-known k-ε turbulence model. The behaviour of the liquid-solid mixture is then described by implementing the Eulerian Mixture model. Liquid velocity fields simulated by CFD have been validated by comparison with PIV (Particle Image Velocimetry) measurements. Computed values of Nhs are compared with good agreement to experimental data obtained with a nephelometric probe. Results obtained at different scales allowed correlating the Nhs value to the volumetric power consumption. [less ▲]

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See detailSol-gel preparation and characterisation of SnO2 powders employed as catalyst for phenol photodegradation
Benhebal, Hadj; Chaib, Messaoud; Léonard, Angélique ULg et al

in Scientia Iranica (2013), 20(6), 1891-1898

Crystallized pure SnO2 powders were prepared by the sol-gel process and were used as photocatalyst for the degradation of phenol under UV light at pH 6.5 and a temperature of 20°C. The physical properties ... [more ▼]

Crystallized pure SnO2 powders were prepared by the sol-gel process and were used as photocatalyst for the degradation of phenol under UV light at pH 6.5 and a temperature of 20°C. The physical properties of photocatalyst were characterized by X-ray diffraction, Scanning Electron Microscopy, nitrogen adsorption-desorption and Ultraviolet-visible diffuse reflectance spectroscopy. The influences of different operating variables such as the pH, the photocatalyst loading, the initial concentration of phenol, were studied to improve the efficiency of phenol degradation. [less ▲]

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See detailInvestigation of liquid flow morphology inside a structured packing using X-ray tomography
Janzen, Anna; Steube, Julia; Aferka, Saïd et al

in Chemical Engineering Science (2013), 12

In this work X-ray tomography is used to analyse the influence of liquid viscosity on liquid flow in a column filled with Mellapak Plus 752Y structured packing. Tomographic measurements are performed at ... [more ▼]

In this work X-ray tomography is used to analyse the influence of liquid viscosity on liquid flow in a column filled with Mellapak Plus 752Y structured packing. Tomographic measurements are performed at various column heights for different liquid flow rates. Water and glycerine aqueous solutions are successively used as working liquids in order to quantify the influence of liquid viscosity on hydrodynamic quantities such as liquid hold-up and gas-liquid interfacial area. As expected, both liquid hold-up and gas-liquid interfacial area increase with liquid flow rate. An increase of liquid viscosity has also a positive impact on liquid hold-up and on gas-liquid interfacial area. In all cases, the measured quantities are not constant along the bed height, leading to fluctuating axial profiles. Furthermore, tomographic images are used to identify different liquid flow patterns (films, contact-point liquid, flooded regions) in the irrigated cross section images. A method based on morphological techniques is proposed to quantify the fraction of liquid flow within each flow pattern depending on flow rate and liquid viscosity. [less ▲]

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See detailPhotocatalytic degradation of phenol and benzoic acid using zinc oxide powders prepared by the sol-gel process
Benhebal, Hadj; Chaib, Messaoud; Salmon, Thierry ULg et al

in Alexandria Engineering Journal (2013), 52(3), 517-523

Photocatalytic degradation of phenol and benzoic acid in aqueous solution was studied using zinc oxide (ZnO) powder synthesized by sol–gel process. Synthesized catalyst was characterized by X-ray ... [more ▼]

Photocatalytic degradation of phenol and benzoic acid in aqueous solution was studied using zinc oxide (ZnO) powder synthesized by sol–gel process. Synthesized catalyst was characterized by X-ray diffraction and transmission electron microscopy. The Brunauer–Emmett–Teller surface area, pHpzc, and the band gap of the catalyst samples were also measured. The influence of various key parameters such as amount of photocatalyst, initial solution pH, and the initial concentration of phenol and benzoic acid was investigated. [less ▲]

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See detailPhotocatalytic degradation of phenol and benzoic acid using zinc oxide powders prepared by the sol-gel process
Benhebal, Hadj; Chaib, Messaoud; Salmon, Thierry ULg et al

in Alexandria Engineering Journal (2013), 52(3), 517-523

Photocatalytic degradation of phenol and benzoic acid in aqueous solution was studied using zinc oxide (ZnO) powder synthesized by sol–gel process. Synthesized catalyst was characterized by X-ray ... [more ▼]

Photocatalytic degradation of phenol and benzoic acid in aqueous solution was studied using zinc oxide (ZnO) powder synthesized by sol–gel process. Synthesized catalyst was characterized by X-ray diffraction and transmission electron microscopy. The Brunauer–Emmett–Teller surface area, pHpzc, and the band gap of the catalyst samples were also measured. The influence of various key parameters such as amount of photocatalyst, initial solution pH, and the initial concentration of phenol and benzoic acid was investigated. [less ▲]

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See detailMesure par tomographie à rayons X de l’influence de la viscosité du liquide sur la morphologie de l’écoulement dans un garnissage structuré
Janzen, Anna; Steube, Julia; Kenig, Evgeny et al

in Récents Progrès en Génie des Procédés (2013), 104

In this work X-ray tomography is used to analyse the influence of liquid viscosity on the local morphology of liquid flow in a column filled with Mellapak Plus 752Y structured packing. Water and glycerine ... [more ▼]

In this work X-ray tomography is used to analyse the influence of liquid viscosity on the local morphology of liquid flow in a column filled with Mellapak Plus 752Y structured packing. Water and glycerine aqueous solutions of various viscosities (1 to 20 cP) are successively used as working liquids. On tomographic images, three different local liquid flow patterns (films, contact-point liquid, flooded regions) may be identified. An image analysis method based on morphological techniques is developed to quantify the fraction of liquid flow within each flow pattern depending on flow rate and liquid viscosity. [less ▲]

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See detailImpact of sludge storage on dewatering and convective drying
Pambou, Yvon-Bert ULg; Salmon, Thierry ULg; Fraikin, Laurent ULg et al

Scientific conference (2012, November 10)

Annual production of sewage sludge in Europe is estimated at more than ten million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge drying ... [more ▼]

Annual production of sewage sludge in Europe is estimated at more than ten million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge drying appears as an essential step after mechanical dewatering. It reduces the costs of storage and transport, allows the stabilization and the hygienization of sludge while increasing its calorific value. However, this process is highly energy consuming and still needs to be optimized as it constitutes an important economic and environmental issue. This implies the improvement of knowledge about sludge drying, including the impact of the mechanical dewatering step. Before studying experimentally the influence of polymers type and dosage use for dewatering on the rheological properties and the drying process, it is necessary to assess the stability of the sludge during of the storage. Because sludge is a living material that can rapidly change, we use the method of experimental design in order to get maximum information with minimal testing, regarding sludge stability during storage. [less ▲]

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See detailDevelopment of optical trajectography device for the lagangian study of turbulent flow inside a stirred tank used in pharmaceutical industry
Collignon, Marie-Laure ULg; Delafosse, Angélique ULg; Delvigne, Frank ULg et al

Poster (2012, September 10)

Stirred tanks are devices that are widely used in various process steps of the pharmaceutical industry. The performance of these processes (animal cell culture, crystallization, flocculation …) strongly ... [more ▼]

Stirred tanks are devices that are widely used in various process steps of the pharmaceutical industry. The performance of these processes (animal cell culture, crystallization, flocculation …) strongly depend on the physico-chemical and hydrodynamic environment present locally in these tanks. To fully describe this local environment, an Eulerian - Lagrangian approach must be adopted in order to establish history of conditions met by a particle as a cell, a crystal or a floc. This approach implies to determine the trajectory followed by the particle. To this aim, the Chemical Laboratory of Liege University has developed a prototype of optical trajectography device. The objective of this paper is to present the device, developments that were necessary for its use and the results obtained. The device is composed of two cameras modeled by a pinhole model which record the position of a bead that has a size equal to 490 µm and that perfectly follows local flow structures. The measured trajectory has been validated by comparing average time velocity fields deduced from it to those measured, in the same operating conditions, by particle image velocimetry (P.I.V.). [less ▲]

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See detailMODELING WASTEWATER SLUDGE DRYING WITH DETERMINATION OF DIFFUSIVITY MOISTURE
Bennamoun, Lyes ULg; Fraikin, Laurent ULg; Salmon, Thierry ULg et al

Scientific conference (2012, September 06)

Convective drying of two different types of wastewater sludges is investigated. Experiments are realised in a micro-dryer, for air temperatures of 80 °C, 140 °C and 200 °C, the velocity and humidity ... [more ▼]

Convective drying of two different types of wastewater sludges is investigated. Experiments are realised in a micro-dryer, for air temperatures of 80 °C, 140 °C and 200 °C, the velocity and humidity remaining the same. The product drying kinetics presents, for all studied cases, three main phases, which are: adaptation phase, constant drying rate phase and falling drying rate. A comparison between two mathematical approaches allows determination of the diffusion coefficient. The value of this coefficient depends on the origin of the wastewater sludge and the operating temperatures. Physical changes such as shrinkage are introduced into the mathematical model. [less ▲]

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See detailPhotodegradation of phenol and benzoic acid by sol-gel-synthesized alkali metal-doped ZnO
Benhebal, H.; Chaib, M.; Léonard, Angélique ULg et al

in Materials Science in Semiconductor Processing (2012), 15(3), 264269

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See detailInvestigation of liquid flow pattern inside a structured packing using X-ray tomography
Aferka, Saïd ULg; Steube, Julia; Janzen, Anna et al

in Proceedings of the 6th International Symposium on Process Tomography, Cape Town, South Africa (2012)

This work focuses on the analysis of X-ray tomographic images of liquid flow distribution within a 1 m high packed column of 10 cm diameter, filled with four Mellapak Plus 752Y elements. Tomographic ... [more ▼]

This work focuses on the analysis of X-ray tomographic images of liquid flow distribution within a 1 m high packed column of 10 cm diameter, filled with four Mellapak Plus 752Y elements. Tomographic measurements are performed at various column heights for different liquid flowrates. Water and aqueous glycerine solutions are successively used as working liquids in order to quantify the influence of liquid viscosity on the spatial distribution of hydrodynamic quantities such as liquid holdup and gas-liquid interfacial area. Logically, both liquid holdup and gas-liquid interfacial area increase with liquid flow rate. An increase of liquid viscosity has also a positive impact on liquid holdup and on gas-liquid interfacial area. In all cases, the measured quantities are not constant along the bed height, leading to fluctuating axial profiles. Depending on the liquid viscosity and flowrate, different liquid flow patterns (films, rivulets, flooded channels) are observed in the irrigated cross section images. A method based on morphological techniques is proposed to quantify the fraction of liquid flow which belongs to each flow pattern. [less ▲]

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See detailEfficient sludge thermal processing: from drying to thermal valorisation
Arlabosse, Patricia; Ferrasse, J. H.; Lecomte, D. et al

in Tsotsas, E.; Mujumdar, A. S. (Eds.) Modern Drying Technology, Vol 4. Energy savings (2012)

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See detailEtude de l’écoulement au sein d’un bioréacteur parallélépipédique à usage unique à agitation pendulo-elliptique
Collignon, Marie-Laure ULg; Droissart, Laurent; Delafosse, Angélique ULg et al

in Récents Progrès en Génie des procédés - A la croisée des sciences et des cultures, pour relever les défis industriels du XXIème siècle (2011, December 01)

Les bioréacteurs à usage unique sont de plus en plus envisagés dans l’industrie pharmaceutique en remplacement de leurs homologues en acier car ils permettent d’éliminer les étapes de lavage et de ... [more ▼]

Les bioréacteurs à usage unique sont de plus en plus envisagés dans l’industrie pharmaceutique en remplacement de leurs homologues en acier car ils permettent d’éliminer les étapes de lavage et de stérilisation tout en réduisant le risque de contamination croisée. Afin de s’insérer dans ce marché en expansion, les firmes ATMI LifeSciences, Pierre Guerrin et Artelis ont développé un bioréacteur à usage unique « Nucleo » composé d’une poche parallélépipédique en plastique souple mélangée par une pale réalisant un mouvement pendulo-elliptique. Différentes études ont démontré les bonnes performances de ce dispositif en termes d’homogénéisation et de maintien en suspension d’une phase solide ainsi que des productivités intéressantes lors de la réalisation de cultures de cellules animales. L’objectif de la présente étude est de caractériser l’écoulement du liquide au sein du bioréacteur grâce à des mesures réalisées par stéréo PIV. L’analyse des profils de vitesse a montré, qu’aux vitesses de rotation étudiées, l’écoulement au sein de la cuve est turbulent. Il apparaît que dans ces conditions, l’écoulement est complètement tridimensionnel et forme une spirale toroïdale plus ou moins déformée autour de l’axe central de la cuve. Il présente une certaine symétrie par rapport à cet axe central. Bien que la cuve soit parallélépipédique, aucune zone morte n’est observée dans les coins de celle-ci. [less ▲]

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See detailMesure par tomographie à rayons X de l’influence de la viscosité sur la distribution du liquide dans une colonne à empilage structuré.
Aferka, Saïd ULg; Steube, Julia; Janzen, Anna et al

in In SFGP (Ed.), Récents Progrès en Génie des Procédés - N° 101 - Des procédés au service du produit au coeur de l'Europe - Actes du XIIIème Congrès de la société Française de Génie des Procédés - Du 29 Nov. au 1er Décembre 2011 - Lille Grand Palais, FRANCE (2011, December)

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See detailModèle hybride Euler-Lagrange pour la description des hétérogénéités dans les bioréacteurs.
Delafosse, Angélique ULg; Delvigne, Frank ULg; Collignon, Marie-Laure ULg et al

in SFGP (Ed.) Récents Progrès en Génie des Procédés - N° 101 - Des procédés au service du produit au coeur de l'Europe - Actes du XIIIème Congrès de la société Française de Génie des Procédés - Du 29 Nov. au 1er Décembre 2011 - Lille Grand Palais, FRANCE (2011, November 29)

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See detailInfluence du stockage des boues de STEP sur les émissions de NH3 et de COV durant leur séchage
Fraikin, Laurent ULg; Salmon, Thierry ULg; Herbreteau, Benjamin et al

Poster (2011, November 29)

Le séchage constitue une étape importante en aval de la déshydratation mécanique en vue de la valorisation agricole ou énergétique des boues de station d’épuration. La teneur en eau peut être réduite à ... [more ▼]

Le séchage constitue une étape importante en aval de la déshydratation mécanique en vue de la valorisation agricole ou énergétique des boues de station d’épuration. La teneur en eau peut être réduite à moins de 5%, diminuant ainsi la masse et le volume des boues et, par conséquent, le coût pour le stockage, la manutention et le transport. L'élimination de l'eau augmente considérablement le pouvoir calorifique inférieur, transformant les boues en un combustible convenable. En outre, les boues séchées peuvent être stabilisées et exemptes d'agents pathogènes en fonction de la température et de la durée de traitement. Les technologies convectives sont largement utilisées pour le séchage des boues. Le principal avantage est la simplicité de la technologie et l’inconvénient majeur résulte de la grande quantité d'air à épurer et désodoriser. Le but des travaux menés par l'Université de Liège et VEOLIA Environnement est d'effectuer une caractérisation en laboratoire des émissions gazeuses en fonction des conditions de séchage. Pour ce faire, il est primordial de garantir une qualité constante de l'échantillon initial tout au long des mesures. En effet, même si elles sont conservées à basse température, les boues peuvent être le siège de dégradations biologiques et les propriétés de séchage peuvent être modifiées. Ainsi, la première partie de ce travail est consacrée à l’étude de l'influence de la durée de stockage des boues à 4°C sur les émissions gazeuses produites au cours de leur séchage convectif. Deux types de boues, l’une ayant subi une digestion et l’autre pas, sont étudiés. L’échantillonnage est effectué après la déshydratation mécanique dans deux stations de traitement des eaux usées situées à proximité de l'Université de Liège. Les échantillons sont stockés dans le laboratoire à 4°C dans un récipient hermétique. Pour effectuer les essais, 300 g de boue sont déposés dans le sécheur sous la forme d’un lit d'extrudés de 6 mm de diamètre. La masse de boue, la concentration en ammoniac et la concentration en composés organiques volatils sont mesurées en ligne respectivement par une balance, un analyseur infrarouge et un détecteur à ionisation de flamme. Des thermocouples permettent le suivi de la température en amont, au sein et en aval du lit de boue. Des essais de séchage sont effectués au jour 0 (= jour du prélèvement), et après 1, 2, 4, 10, 17 et 20 jours sous les conditions suivantes : température de l'air = 140°C; vitesse superficielle de l'air = 1 m/s; humidité absolue = 0,005 kgeau/kgair sec. La seconde partie du travail a été réalisée sur un échantillon de boue non digérée conservé à 12°C pour simuler des conditions réelles de stockage. Les essais de séchage ont été menés le jour de prélèvement et après 4, 10 et 20 jours, avec des conditions opératoires similaires. L’étude réalisée avec un stockage à 4°C montre que les émissions gazeuses sont maximales le jour du prélèvement, diminuent fortement durant les deux premiers jours de stockage pour atteindre un niveau constant durant deux semaines avant d’augmenter. Lors du stockage à 12°C, les émissions d’ammoniac et de COV sont multipliées respectivement par un facteur 40 et 4 entre le jour 0 et le jour 20. Ces résultats mettent en évidence l’impact des conditions et de la durée de stockage sur les émissions lors du séchage des boues et montrent l’importance de sécher les boues le plus rapidement possible pour limiter les nuisances. [less ▲]

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See detailSimulation d’un écoulement de gaz dans un empilage structuré par la méthode des réseaux de Boltzmann
Beugre, Djomice; Calvo, Sébastien ULg; Crine, Michel ULg et al

in SFGP (Ed.) Récents Progrès en Génie des Procédés - N° 101 - Des procédés au service du produit au coeur de l'Europe - Actes du XIIIème Congrès de la société Française de Génie des Procédés - Du 29 Nov. au 1er Décembre 2011 - Lille Grand Palais, FRANCE (2011, November 29)

Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental ... [more ▼]

Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental measurements and with known correlations. They are also compared with simulations using a classical CFD code. In all cases, the agreement is very good. An original method based on the simulated axial velocity profiles is proposed to caracterize the gas flow regime. [less ▲]

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