Chemical Engineering Science 100 (2013) 23–32
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Experimental hydrodynamic study of valve trays R. Brahem a,n, A. Royon-Lebeaud a, D. Legendre b, M. Moreaud a, L. Duval c a b c
IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, BP 3 - 69360 Solaize, France IMFT, 1 Allée du Professeur Camille Soula, 31400 Toulouse, France IFP Energies nouvelles, 1 et 4, avenue de Bois-Préau 92852 Rueil-Malmaison Cedex, France
H I G H L I G H T S
Hydrodynamic measurements on a rectangular valve tray column are carried out. Emulsion profiles are measured and analyzed over a large range of liquid and gas rates. Three system limits are identified: dumping, weeping and pre-flooding. Correlations for these limits are proposed.
art ic l e i nf o
a b s t r a c t
Article history: Received 5 September 2012 Received in revised form 8 March 2013 Accepted 17 March 2013 Available online 29 March 2013
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 1.26 m per 0.1905 m 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 3.5 Pa0.5. 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. & 2013 Elsevier Ltd. All rights reserved.
Keywords: Absorption Hydrodynamics Multiphase flow Scale up Valve trays Emulsion height profiles
1. Introduction Valve trays are commonly used as internals in acid gas sweetening process. In this process natural gas, highly charged with acid compounds (mainly carbonic gas and hydrogen sulphide), is treated using aqueous amines solutions. Industrial units design involves the determination of two main parameters which are column diameter and height. The diameter is controlled by two phase flow hydrodynamic behaviour (weeping, flooding). Total column height is controlled by mass transfer parameters. Because of flow complexity on the tray, the design of absorption columns still relies on empirical correlations developed on pilot units. CFD modelling is a possible way of enhancement but
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Corresponding author. Tel.: +33 4 37 70 20 00; fax: +33 4 37 70 20 08. E-mail address:
[email protected] (R. Brahem).
0009-2509/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ces.2013.03.030
only few works have been realized (Li et al., 2009; Jiang et al., 2012) and thus could not substitute experimental works yet. Available correlations in the literature present large discrepancies in shape, results, and choice of influent parameters because of their dependence to the pilot units. In addition, most