References of "Toye, Dominique"
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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 detailAXIAL IMPELLER SELECTION FOR ANCHORAGE DEPENDENT ANIMAL CELL CULTURE IN STIRRED BIOREACTORS: METHODOLOGY BASED ON THE IMPELLER COMPARISON AT JUST-SUSPENDED SPEED OF ROTATION
Collignon, Marie-Laure ULg; Delafosse, Angélique ULg; Crine, Michel ULg et al

in Chemical Engineering Science (2010), 65(22), 5929-5941

Animal cells, which are nowadays essential for the industrial production of proteinic compounds, are commonly cultivated inside stirred tank bioreactors. In case of anchorage dependent cells, they are ... [more ▼]

Animal cells, which are nowadays essential for the industrial production of proteinic compounds, are commonly cultivated inside stirred tank bioreactors. In case of anchorage dependent cells, they are usually fixed on microcarriers. The choice of agitation conditions (impeller type, rotational speed…) in this type of process is not an easy task as it has to fulfil three potentially conflicting goals: (1) maintaining microcarriers in complete suspension, (2) homogenizing the culture medium, and (3) limiting mechanical constraints generated by the hydrodynamics on the cells. The aim of this study is to present an original methodology to select the most appropriate axial impeller for this specific application. Seven propellers are preselected on basis of their characteristics available in the literature. Instead of comparing impellers at a given rotational speed or a given power input, they are compared at their respective minimum impeller rotational speed that leads to a complete microcarrier suspension, i.e. at their respective just-suspended speed Njs. They are then compared at higher rotational speeds N, expressed as multiples of Njs. The impeller classification is based on the intensity of mechanical constraints they produced, evaluated from: (1) the macro-shear rate quantified by the spatial derivative of time average velocity fields measured by P.I.V, (2) the micro-shear rate characterized by the ratio between the microcarrier diameter to the average Kolmogorov scale computed from power input measurements, and (3) the impact of microcarrier collisions on cells described via the Turbulent Collision Severity index also computed from power input measurements. Results show that the 125 mm diameter TTP impeller (Mixel) and the 150 mm diameter Elephant Ear impeller (Applikon) produce the smallest mechanical constraints at their just-suspended speed (50 rpm and 20 rpm, respectively). Moreover, the mechanical constraints they produce increase more slowly with the N/Njs ratio than the mechanical constraints produced by other impellers. These propellers are thus even more advantageous if rotational speeds higher than the just-suspended speed have to be used. [less ▲]

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See detailX-ray tomography : a key for revealing local behavior of fluids in packed beds
Toye, Dominique ULg; Marchot, Pierre ULg; Crine, Michel ULg

Scientific conference (2010, October 28)

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See detailInfluence of medium composition on oxygen transfer rate in animal cell culture
Toye, Dominique ULg; Galifi, A.; Salmon, Thierry ULg et al

in Canadian Journal of Chemical Engineering (2010), 88(4), 671-676

Experiments were conducted in a 0.25m diameter bubble column to investigate the effect of medium composition on oxygen transfer rate. Aqueous solutions, the composition of which mimics a mammalian cell ... [more ▼]

Experiments were conducted in a 0.25m diameter bubble column to investigate the effect of medium composition on oxygen transfer rate. Aqueous solutions, the composition of which mimics a mammalian cell culture medium, are used. The effect on oxygen transfer rate of additives used to protect cells against local hydrodynamic stresses induced by bubble coalescence and bursting is addressed, in the range of operating conditions (aeration rates) met in animal cell cultures. The mass transfer coefficient, the liquid viscosity and surface tension, and the bubble size distribution are measured as a function of liquid composition and of gas superficial velocity, allowing to decouple the effects of the different additive on kL and on a. [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 detailComparison of hydrodynamic parameters obtained by 2D measurements in a flat rectangular column with X-ray radiography and data from literature on 3D columns
Calvo, Sébastien ULg; Beugre, Djomice Antoine ULg; Crine, Michel ULg et al

Poster (2010)

Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as ... [more ▼]

Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as with a gas-liquid counter-current flow. Hydrodynamic parameters are compared to experimental results obtained in 3D columns found in the literature, as well as to literature model predictions and to values computed using an in-house Lattice Boltzmann CFD simulation code. [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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