Processing of X-ray tomographic images: A procedure adapted for the analysis of phase distribution in MellapakPlus 752.Y and Katapak-SP packings

We developed a 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 the present study, the procedure was developed and validated for MellapakPlus 752.Y and Katapak-SP packings, but it may be applied to any type of metallic or modular packing of similar dimensions. Steps of tomographic image processing and associated parameters (threshold, calibration factors for solid and liquid phase) were first determined on images of dry and flooded packing elements of MellapakPlus 752.Y. The parameter values were then adapted to analyse images of dry and flooded packing elements of Katapak-SP, which are made of an alternation of MellapakPlus 752.Y sheets and catalytic baskets. In a certain way, MellapakPlus 752.Y and Katapak-SP (11 and 12), the global geometrical properties of which are well known, are used as physical phantoms to develop a validated image post-processing procedure. The latter is used to quantitatively analyse liquid distribution images in irrigated MellapakPlus 752.Y and Katapak-SP (11 and 12) packings, giving access to spatial distribution of local values of hydrodynamic quantities such as the liquid holdup and gas-liquid interfacial area. Global values of the liquid holdup, relative to the whole packed bed volume are determined by averaging tomographic results over the column height. They are successfully compared with bed scale data measured on the same MellapakPlus 752.Y and Katapak-SP (11 and 12). This analysis further validates the procedure used for the processing of tomographic irrigated images. So the proposed methodology enables one to obtain quantitative information on the spatial distributions of structural quantities as well as of hydrodynamic quantities in complex metallic packings, which are fully validated on the basis of a comparison with global values obtained by well-established measurement techniques. (C) 2011 Elsevier Ltd. All rights reserved.