CHEMICAL ENGINEERING TRANSACTIONS VOL. 43, 2015 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Chief Editors: Sauro Pierucci, Jiří J. Klemeš Copyright © 2015, AIDIC Servizi S.r.l., I SBN 978-88-95608-34-1; I SSN 2283-9216 How Does Radial Convection Influence the Performance of Membrane Module for Gas Separation Processes? Maria Anna Murmura *a , Luca Turchetti b , Rosaria Augelletti a , Maria Cristina Annesini a , Stefano Cerbelli a a Dipartimento di Ingegneria Chimica Materiali Ambiente, Sapienza Università di Roma, Via Eudossiana 18 – 00184 Rome (Italy) b ENEA, Italian Agency for New Technologies, Energy and Environment Technical Unit for Renewable Energy Sources UTRINN, Via Anguillarese 301 – 00123 Rome (Italy) mariaanna.murmura@uniroma1.it A two-dimensional axial-symmetric isothermal model, based on full coupling between mass and momentum transport, has been developed to describe the separation of a binary gaseous mixture in a packed bed membrane module. Steady-state conditions have been studied. The gaseous mixture to be separated enters an annular gap between two co-axial cylinders. The inner wall of the outer cylinder is impermeable to both components, whereas a membrane, with infinite selectivity towards one of the components, is supported onto the outer wall of the inner cylinder. A radial flux of the permeating components is therefore present. The main focus was on the determination of the influence of radial convection on the performance of the separator, which has been analysed in terms of three dimensionless groups. Different transport regimes could be identified, corresponding to different values of the dimensionless groups. The impact of radial convection has been assessed by comparing model predictions with those of a fully uncoupled one-dimensional model. A discrepancy up to 20% of the recovery has been observed in industrially relevant ranges of the parameters. 1. Introduction Integration of reaction and separation in a single unit may bring to significant increases in the efficiency of many chemical processes (Giaconia et al., 2013). Membrane reactors have been studied experimentally (Santucci et al., 2011) and models have been widely presented in literature. In most models the radial component of velocity is neglected, without a quantitative analysis of the errors caused by this assumption. This is found for example in Godini et al. (2014), who studied ethylene production, and in Jin et al. (2000), who studied partial oxidation of methane. As pointed out by Nekhamkina and Sheintuch (2014), these errors may concern the evaluation of both the velocity profiles in the reactor and the total recovery of the permeating component. A more accurate model may therefore be necessary to understand the system’s behaviour, and to carry out an efficient optimization of reactor design. Studies in this direction will become increasingly important as higher permeance membranes are developed. In the present work a simple gas separation is studied as a basis for membrane reactor modelling. A two- dimensional model is developed in which the coupling between mass and momentum transport is considered. The results obtained are compared with a simpler model, where fluid-dynamics are decoupled from transport of the permeating species. Model predictions are compared to determine the cases in which the simplified model describes the behaviour of the reactor accurately enough. 2. Model Development A 2D axial-symmetric isothermal steady-state model has been developed to describe the separation of a binary gaseous mixture. The shell and tube configuration described above is often found when dealing with DOI: 10.3303/CET1543178 Please cite this article as: Murmura M.A., Turchetti L., Augelletti R., Annesini M.C., Cerbelli S., 2015, How does radial convection influence the performance of membrane module for gas separation processes?, Chemical Engineering Transactions, 43, 1063-1068 DOI: 10.3303/CET1543178 1063