References of "Aferka, Saïd"
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See detailModellierung des Trennverhaltens wässriger Systeme in Packungskolonnen basierend auf tomographischen
Janzen, Anna; Steube, Julia; Aferka, Saïd ULg et al

Conference (2012, March)

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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 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 detailX-ray CT study of the influence of liquid viscosity on fluid phase distribution in modular catalytic packings
Aferka, Saïd ULg; Viva, Aurora; Brunazzi, Elisabetta et al

in Chemical Engineering Transactions (2011), 24

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an ... [more ▼]

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an aqueous solution of glycerine, the viscosity of which equals 10 cP, are used as feed liquids. The estimation of liquid holdup is of great interest due to its strong influence on pressure drop, on solid wetting and on heat and mass transfer coefficients. The experimental technique used is high energy X-ray tomography, which is a unique technique to visualize the local liquid distribution inside the complex structure of packings and to quantify the liquid holdup at different scales. [less ▲]

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See detailTomographic measurement of liquid hold up and effective interfacial area distributions in a column packed with high performance structured packings
Aferka, Saïd ULg; Viva, Aurora; Brunazzi, Elisabetta et al

in Chemical Engineering Science (2011), 66

In this paper, we report on the use of a high energy and high resolution X-ray tomograph to visualize and quantify the distribution of liquid hold up and of gas-liquid interfacial area in a 0.1m diameter ... [more ▼]

In this paper, we report on the use of a high energy and high resolution X-ray tomograph to visualize and quantify the distribution of liquid hold up and of gas-liquid interfacial area in a 0.1m diameter column filled with MellapakPlus 752.Y packing elements. A standard air-water system at room temperature and atmospheric pressure was used. Tomographic measurements have been carried out in a large number of packing cross sections situated at different heights between the top and the bottom of the packed column, giving access to the evolution of axial profiles of liquid hold up and of gas-liquid interfacial area as a function of the operating conditions. Gas-liquid interfacial area values were also measured by a chemical method (CO2 absorption from air into a caustic solution). For the first time, a whole set of gas-liquid interfacial area values evaluated from tomographic images are interestingly compared with values measured by a chemical method. A comparison is also presented with literature models. [less ▲]

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See detailDetermination of liquid hold-up and flow distribution inside modular catalytic structured packings
Viva, Aurora; Aferka, Saïd ULg; Toye, Dominique ULg et al

in Chemical Engineering Research & Design : Transactions of the Institution of Chemical Engineers Part A (2011), 89

This paper presents the results of a study carried out to examine liquid hold-up and flow distribution in a 0.1m internal diameter column filled with catalytic structured packing Katapak-SP. Information ... [more ▼]

This paper presents the results of a study carried out to examine liquid hold-up and flow distribution in a 0.1m internal diameter column filled with catalytic structured packing Katapak-SP. Information has been gathered at local scale by means of a non-intrusive high energy X-ray tomograph. Measurements have been carried out in a large number of packing cross sections situated at different heights between the top and bottom of the packed column, giving access to the evolution of axial profiles of liquid hold-up in the open channels (separation zone) and in the catalytic baskets (reaction zone) as a function of the liquid load. The total hold-up, evaluated by averaging local tomographic values over the packed volume, was compared with global hold-up data obtained by traditional methods, like draining and RTD measurements. A method was also proposed to deduce the distribution of liquid flowrate, between the reaction and the separation zones, from hold-up distribution measured by tomography. The methodology was validated by comparison with experimental data obtained by collecting separately the liquid flowing out of the two zones at the bottom of the packed bed. The obtained results are invaluable to improve the description of hydrodynamics in rate based performance models. [less ▲]

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See detailProcessing of X-ray tomographic images: a procedure adapted for the analysis of phase distribution in MellapakPlus 752.Y and Katapak-SP packings
Viva, Aurora; Aferka, Saïd ULg; Brunazzi, Elisabetta et al

in Flow Measurement & Instrumentation (2011), 22

We developed a simple practical methodology to face common problems encountered in the analysis of tomographic images to get quantitative information on phase distributions in gas liquid contacting ... [more ▼]

We developed a simple practical methodology to face common problems encountered in the analysis of tomographic images to get quantitative information on phase distributions in gas liquid contacting columns packed with complex metallic packings. In particular, the procedure (thresholding and normalisation) was developed and validated on images of geometrically well known Mellapak Plus 752 Y packings. The methodology was extended to images of Katapak-SP modular packings which are made of an alternation of Mellapak Plus 752 Y sheets and catalytic baskets. Global liquid hold-up, obtained by averaging tomographic results over the column height, were found in agreement with bed scale data measured on the same Mellapak Plus 752 Y and Katapak-SP (11 and 12) packings at a given liquid load. Moreover, gas-liquid interfacial area were calculated and reported to the installed geometric area. [less ▲]

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See detailEtude de l'hydrodynamique dans une colonne de distillation réactive: Mesure de la distribution des phases par tomographie à rayons X.
Aferka, Saïd ULg

Doctoral thesis (2010)

Le mémoire concerne l’étude de l’hydrodynamique des écoulements dans des lits fixes parcourus par un écoulement à contre courant de gaz et de liquide. Il est plus particulièrement consacré à l’analyse par ... [more ▼]

Le mémoire concerne l’étude de l’hydrodynamique des écoulements dans des lits fixes parcourus par un écoulement à contre courant de gaz et de liquide. Il est plus particulièrement consacré à l’analyse par tomographie à rayons X de la distribution spatiale des phases liquide et solide dans des empilages de distillation et de distillation réactive. Le principe de la distillation réactive est de réaliser, dans une même colonne, une réaction chimique exothermique et la séparation des produits par distillation. L’industrie chimique marque beaucoup d’intérêt pour ce type d’appareil en raison des nombreux avantages qu’il offre : une réduction des investissements, puisqu’un seul appareil est utilisé au lieu de deux ; une très grande intégration énergétique des étapes de réaction et de séparation, puisque la chaleur générée par la réaction est directement utilisée pour la distillation ; la possibilité d'augmenter la conversion dans le cas des réactions limitées à l'équilibre ; … Les empilages utilisés en distillation réactive présentent généralement une structure modulaire. Chaque élément comporte une ou plusieurs zones catalytiques, dans lesquelles la réaction se déroule et une ou plusieurs zones de séparation, où la distillation peut être réalisée. Vu la structure extrêmement complexe de ces empilages, la compréhension et la description des écoulements en leur sein sont des tâches particulièrement ardues que très peu d’équipes de recherches ont entamées jusqu’à présent. Le but du présent travail de thèse est de collecter une information expérimentale aussi précise et aussi complète que possible, permettant de déterminer les mécanismes hydrodynamiques qui interviennent dans les empilages de distillation réactive. La tomographie à rayons X est utilisée pour mesurer la distribution des phases à différentes échelles, depuis l’échelle locale des détails de l’empilage, jusqu’à l’échelle de la colonne dans son ensemble. Les résultats obtenus permettent non seulement de quantifier les grandeurs hydrodynamiques macroscopiques comme la rétention ou l’aire interfaciale mais, ils permettent également et surtout d’expliquer leur évolution en fonction de la structure de l’empilage et des conditions opératoires. [less ▲]

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See detailLiquid load point determination in a reactive distillation packing by x-ray tomography
Aferka, Saïd ULg; Viva, Aurora ULg; Brunazzi, Elisabetta et al

in Canadian Journal of Chemical Engineering (2010), 88(4), 611-617

In this paper, we report on the use of Xray tomography to determine the liquid load point in 0.1m diameter modular catalytic distillation packings KatapakSP11 and KatapakSP12. The liquid load point ... [more ▼]

In this paper, we report on the use of Xray tomography to determine the liquid load point in 0.1m diameter modular catalytic distillation packings KatapakSP11 and KatapakSP12. The liquid load point corresponds to the overall packed bed liquid load above which there is an increment in the liquid flowing outside the catalytic baskets and the catalytic baskets themselves are saturated with liquid. From tomographic images, we show that several factors affect the wetting and filling of catalytic baskets. The complex hybrid structure of catalytic packings influences the liquid distribution inside the elements. The liquid preferentially fills the external catalytic baskets because they receive the liquid not only from the packing element situated above but also from the wall wipers. Moreover, liquid holdup inside a catalytic basket section depends significantly on the vertical position in the packing element and on the position of the packing in the column packed bed. The counter–current gas flow speeds up the process of liquid filling of the baskets, also for low liquid loads. The nonuniform distribution of liquid in catalytic basket which is observed experimentally makes the identification of a unique liquid load point not straightforward. [less ▲]

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See detailX-ray CT study of the influence of liquid viscosity on fluid phase distribution in modular catalytic packings
Aferka, Saïd ULg; Viva, Aurora; Toye, Dominique ULg et al

in AIDIC Conference series (2010), 10

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an ... [more ▼]

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an aqueous solution of glycerine, the viscosity of which equals 10 cP, are used as feed liquids. The estimation of liquid holdup is of great interest due to its strong influence on pressure drop, on solid wetting and on heat and mass transfer coefficients. The experimental technique used is high energy X-ray tomography, which is a unique technique to visualize the local liquid distribution inside the complex structure of packings and to quantify the liquid holdup at different scales. [less ▲]

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See detailMeasurement of liquid hold-up in catalytic structured packings: comparison of different experimental techniques
Viva, Aurora ULg; Aferka, Saïd ULg; Toye, Dominique ULg et al

in de Haan, A. B.; Kooijman, H.; Gorak, A. (Eds.) Proceedings of 9th Distillation and Absorption Conference (DA2010), Eindhoven, Pays-Bas, 12-15 septembre 2010 (2010)

This paper presents the results of an experimental study carried out to examine liquid hold-up in 100 mm diameter catalytic structured packing Katapak-SP. Two versions of the packing have been ... [more ▼]

This paper presents the results of an experimental study carried out to examine liquid hold-up in 100 mm diameter catalytic structured packing Katapak-SP. Two versions of the packing have been investigated. Both global and local measurements were carried out on the very same packings, using water at ambient conditions as working liquid. To this scope, traditional methods like draining techniques were used to obtain global hold-up values. A non-intrusive high energy X-ray tomography was used for gathering information on local scale and study axial distribution of the liquid hold-up over the packed column, inside and outside the catalyst containing baskets. The total liquid hold-up of the catalytic packed bed was evaluated by averaging hold-up values obtained at different cross sections over the corresponding volume. Very good agreement was found between global values estimated with the different techniques. The experimental results are useful for supporting theoretical developments in hydrodynamic and mass transfer modeling. [less ▲]

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See detailLiquid hold-up measurement in Mellapak Plus 752Y packed bed using X-ray tomography
Aferka, Saïd ULg; Viva, Aurora ULg; Brunazzi, Elisabetta et al

in VCIPT (Ed.) Proceedings of 6th World Congress On Industrial Process Tomography (WCIPT6), Beijing, China, 6-9 Septembre 2010 (2010)

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See detailInfluence of the viscosity on liquid hold-up in modular catalytic packings
Aferka, Saïd ULg; Viva, Aurora ULg; Brunazzi, Elisabetta et al

Conference (2010)

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See detailInterfacial area measurement in a catalytic distillation packing using high energy x-ray CT
Aferka, Saïd ULg; Marchot, Pierre ULg; Crine, Michel ULg et al

in Chemical Engineering Science (2010), 65(1), 511-516

In this paper, we report on the use of X-ray tomography to visualize and quantify the gas–liquid interfacial area in modular catalytic distillation packing elements. The calculation method is based on ... [more ▼]

In this paper, we report on the use of X-ray tomography to visualize and quantify the gas–liquid interfacial area in modular catalytic distillation packing elements. The calculation method is based on processing of tomographic images. It is validated by comparing specific surface area determined on dry packings (Mellapak™ 752Y and Katapak™ SP12) tomographic binary images (gas and solid) to values announced by manufacturers, based on geometrical considerations. These data agree fairly well. However, tomographic images show that the specific area is not distributed uniformly over the height of a packing element due to the presence of perforations in corrugated sheets and of wall wipers between the packing and the column wall. X-ray tomography is a unique technique to access to the spatial distribution of these geometrical details in a non-intrusive way. The method used to determine the specific surface area of dry packing is then applied to irrigated packing in order to determine the gas–liquid interfacial area. The axial distribution of the interfacial area is non-uniform and is correlated to the packing specific area. The maxima of the specific surface area correspond to the presence of wall wipers. The gas–liquid interfacial area averaged over the column length is determined. It increases logically with the liquid superficial velocity and slightly with the gas velocity. The effect of the gas velocity is however more pronounced when reaching loading point. [less ▲]

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See detailLiquid load point measurement in a reactive distillation packing by x-ray tomography
Aferka, Saïd ULg; Viva, Aurora ULg; Brunazzi, Elisabetta et al

Poster (2009, August)

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See detailSimulations of Structures in Packed Columns and Validation by X-ray Tomography
Caulkin, R.; Jia, X.; Xu, C. et al

in Industrial & Engineering Chemistry Research (2009), 48(1), 202-213

Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray Computerized tomography (CT). Two modified versions of what was previously ... [more ▼]

Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray Computerized tomography (CT). Two modified versions of what was previously a purely geometrical, digitally based packing algorithm were implemented. Both are aimed at incorporating the effects of particle interaction forces, one utilizing the distinct element method (DigiDEM) and the other an intermediate solution (collision-guided packing or DigiCGP). This article summarizes the models and the simulations performed using these two modified versions of DigiPac and, for model validation purposes, compares the predicted results with the corresponding X-ray tomographic scans of packed columns, in terms of bulk density, local packing density profiles, and pellet orientation distributions. For packed beds of relatively large and identical pellets, the simulation results indicate that particle-particle and particle-wall interactions cannot be ignored if realistic packing structures are to be obtained by simulation and even a simplistic treatment of these interactions can produce significantly more realistic packing structure than none at all. [less ▲]

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See detailValidation of DigiPac Simulations of packed columns using x-ray microtomography
Jia, X.; Xu, C.; Caulkin, R. et al

in Mc Cann, H.; Johansen, G. A. (Eds.) Proceedings of the 5th World Congress on Industrial Process Tomography, Bergen, Norway, September 6-9, 2007 (2007, September)

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See detailMesure de la distribution des phases dans une mousse métallique par radiographie et micro-tomographie à rayons X
Toye, Dominique ULg; Aferka, Saïd ULg; Calvo, Sébastien ULg et al

in Récents Progrès en Génie des Procédés - N°95 - Actes des 5èmes Journées francophones sur les réacteurs gaz-liquide et gaz-liquide-solide, 12-15 juin 2007, Carry-le-Rouet, France (2007, June)

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See detailMesure de la distribution des phases dans une colonne de distillation réactive par tomographie à rayons X
Aferka, Saïd ULg; Saroha, A.; Toye, Dominique ULg et al

in Récents Progrès en Génie des Procédés - N°95 - Actes des 5èmes Journées francophones sur les réacteurs gaz-liquide et gaz-liquide-solide, 12-15 juin 2007, Carry-le-Rouet, France (2007)

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See detailModélisation d'un écoulement diphasique au sein d'un empilage structuré
Calvo, Sébastien ULg; Beugre, Djomice Antoine ULg; Aferka, Saïd ULg et al

in SFGP (Ed.) Récents Progrès en Génie des procédés - N°96 - Des réponses industrielles pour une société en mutation - Actes du 11ème Congrès de la Société française de Génie des procédés - 9-11 octobre 2007, Saint Etienne, France (2007)

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