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 were 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

No abstract

No abstract

No abstract

In this paper, we report on the use of X-ray tomography to determine the liquid load point in 0.1 m diameter modular catalytic distillation packings Katapak-SP11 and Katapak-SP12. 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 hold-up 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 non-uniform distribution of liquid in catalytic basket which is observed experimentally makes the identification of a unique liquid load point not straightforward.Nous donnons dans ce document un compte rendu de l'utilisation de la tomographieà rayon X dans la détermination du point de chargement du liquide dans leséléments modulaires de distillation catalytiques de 0,1 m de diamètre Katapak-SP11 et Katapak-SP12. Le point de chargement du liquide correspondà la charge liquide d'un lit fixe rempli au-dessus de laquelle il y a un incrément dans l'écoulement du liquide hors des paniers catalytiques et les paniers catalytiques sont eux-mêmes saturés de liquide. Nous démontrons,à partir des images tomographiques, que plusieurs facteurs affectent la fluidisation et le remplissage des paniers catalytiques. La structure hybride complexe deséléments de lit catalytique influence la distribution du liquideà l'intérieur deséléments. Le liquide remplit préférentiellement les paniers catalytiques externes parce qu'ils reçoivent le liquide non seulement de l'élément du lit se trouvant au-dessus maiségalement des pales raclantes des parois. En outre, la retenue de liquideà l'intérieur d'une section du panier catalytique dépend de manière significative de la position verticale dans l'élément du lit et de la position de l'élément dans le lit rempli. L'écoulement de gazà contre courant accélère le processus du remplissage du liquide dans les paniers, aussi pour les charges liquides faibles. La distribution non uniforme du liquide dans le panier catalytique qui est observée expérimentalement fait que l'identification d'un point de chargement unique n'est pas si simple.