Membrane reactors are widely used within the industry to selectively separate particles or species from a stream. Well-known examples are the filtration of dust particles from flue gas or reverse-osmosis for producing drinking water from seawater or other pharmaceutical related separations. The main benefit of this reactor type is the modular structure and the low energy consumption compared to other separation methods.
At AIChE Spring Meeting 2015 an approach to simulate membrane processes by using the commercially available CFD code STAR-CCM+ was presented. The results showed very good agreement with experimental results and had the outcome that the performance and efficiency of a membrane reactors is not only a function of the molecular functionality of the membrane itself but also of the flow characteristics and species distribution in the reactor.
Based on this work the separation process in a full-scale multi-tubular membrane module consisting of more than 300 tubes like shown in the picture above is investigated. Two different approaches are compared: The first one uses a 1D-3D coupled approach that neglects radial profiles in the retentate side tubes while the permeate side gets spatially resolved. The second method uses advanced meshing technique to allow an efficient fully spatially resolved CFD simulation of the whole reactor. The results reveal the limits of one dimensional approaches and show how numerical simulation can help do develop more efficient reactors by doing slight design changes.