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Experimental measurements of hydrodynamic and interfacial area parameters are carried out over two rectangular pilot scale valve tray columns. The effect of tray path length on extrapolation between the two columns is studied and phenomenological correlations for hydrodynamic and interfacial area are proposed. Correlations are compared both to literature and to industrial results showing good agreement and a significant improvement for the prediction of industrial conditions. Discrepancies preventing an accurate description of industrial trends are highlighted through comparison between typical emulsion height profiles on both columns. [ABSTRACT FROM AUTHOR]

Valve trays column design for gas treatment still relies on empirical correlations developed on pilot units. The available correlations lead to large discrepancies and thus more experimental works are needed. The present hydrodynamic study was carried out on a Plexiglas 1.26m per 0.1905m absorption column containing four V-4 Glitsch valve trays. Water/air system was used at atmospheric pressure and ambient temperature. Liquid rate per weir unit length was varied between 3.2×10−3 m3.(m.s)−1 and 24.3×10−3 m3.(m.s)−1 and the kinetic gas factor between 0 and 3.5Pa0.5. The following hydrodynamic parameters were determined: tray pressure drop, valves pressure drop, clear liquid height, mean emulsion height and liquid mean hold up on the tray. Correlations for clear liquid height, liquid mean hold up and emulsion height are proposed. Emulsion profiles characterisation was possible due to video records post-processing. Four different behaviours are identified for emulsion profiles according to liquid and gas velocities. Significant behaviour changes on the hydrodynamic parameters allowed the identification of three system limits: dumping, weeping and pre-flooding. Correlations are proposed for these limits and an operational diagram is presented. [ABSTRACT FROM AUTHOR]

This work has been carried out in the framework of post-combustion capture process development. Considering the huge amount of gases to be treated and the constraints in terms of pressure drop, it appears that the absorption column will be equipped with high efficiency high capacity packings such as structured packings. The present paper focuses on the CFD modellisation of the two-phase flow within this complex geometry. For limited computational resources reasons, it is presently impossible to run computations at large scales taking into account the gas–liquid interaction and the real geometry of the packing and original approaches must be developed. In the present work, a multi-scale approach is proposed. It first considers liquid–wall and liquid–gas interaction at small scale via two-phase flow calculations using the VOF method. Second, the latter results are used in three-dimensional calculations run at a meso-scale corresponding to a periodic element representative of the real packing geometry. Last, those results are further used at large scale in three-dimensional calculations with a geometry corresponding to a complete column. Results are compared with experimental data and with other CFD simulations in terms of liquid hold-up, pressure drop and unit operation. Some suggestions are made for further development. [Copyright &y& Elsevier]

Abstract: Computational fluid dynamics is used to describe both wetting efficiency in simple configurations of stacked solid particles and catalyst efficiency inside such partially wetted catalyst particles. The volume of fluid (VOF) model used to describe hydrodynamics leads to realistic and promising results for surface wetted ratio. Catalyst efficiency simulations have been performed for different shapes of particles and different Thiele modulus values for a first order reaction rate. Results show that for all the shapes studied, catalyst efficiencies of partially wetted particles can be calculated by simply using a modified Thiele modulus defined as ratio of the actual Thiele modulus to the wetting efficiency f. [Copyright &y& Elsevier]