Investigation of liquid hold-up in structured packings under flooding conditions using ultra-fast electron beam X-ray tomography


Investigation of liquid hold-up in structured packings under flooding conditions using ultra-fast electron beam X-ray tomography

Janzen, A.; Barthel, F.; Schubert, M.; Hampel, U.; Kenig, E. Y.

Structured packings are column internals widely used in countercurrent separation processes, such as distillation or absorption. Due to the countercurrent flow, flooding of the packed column represents the upper operation limit. At this point, the high shear stresses between the phases cause a liquid-phase accumulation accompanied by the dispersion of the gas phase. Shifting the flooding point towards higher loads by modifying the packing geometry would result in a capacity increase of the column. Therefore, understanding of the fluid flow character inside the packing is necessary both for process modelling and for packing optimisation.
In this work, a new measurement technique, ultra-fast electron beam X-ray tomography, is applied to investigate dynamic phase distribution in gas-liquid contact devices. Contrary to classical tomographic systems, electron beam X-ray tomography does not require a rotating object or a source-detector setup. Instead, an electron beam is very rapidly swept across a target producing a moving X-ray spot. Thus, a high temporal resolution with frame rates of 2000 images per second and higher can be achieved.
The liquid-phase distribution in an experimental setup containing a DN80 column was measured for the system water/air at different gas and liquid loads. Two packing types with different specific surface area (Montz B1-350MN and B1-500MN) were used to investigate the influence of the packing geometry. The reconstructed image series were post-processed and analysed with respect to the spatial distribution of the liquid and its hold-up before and at the flooding point. Furthermore, the liquid hold-up measurement results were compared with those obtained from a conventional draining method. The new fast measurement technique is capable of providing new insights on the liquid flow dynamics.

  • Lecture (others)
    ACHEMA 2012, 18.-22.06.2012, Frankfurt am Main, Deutschland

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Publ.-Id: 17604