Numerical CFD simulation of a batch stirred tank reactor with stationary catalytic basket

The liquid flow field in a stirred reactor, with catalyst particles contained in a fixed basket, has been investigated by means of CFD RANS (Reynolds-Averaged Navier-Stokes) simulations, using a Realizable k-epsilon model. First results without basket showed a good agreement between simulations and literature, by comparing impeller power numbers (N-p) and liquid velocity pattern. The basket was simulated as a porous medium characterized by its porosity and permeability using the Brinkman-Forchheimer model. When adding the basket, the flow pattern also presents a recirculation but at a lower velocity magnitude. The liquid flows through the central zone of the basket in a radial outward direction. The zones of the catalytic basket above and below this central zone are also crossed radially but in the opposite direction (inward) and at a lower velocity. Using the computed velocities in the basket and the Ranz-Marshall correlation, liquid/solid mass transfer coefficients (k(s)) were estimated in the different zones of the catalytic basket with reasonable values. We conclude from these calculations that there is a recirculation pattern in the basket and a non-uniformity of velocities inducing differences in mass transfer coefficients in the catalytic basket. Despite the simplicity of the model, results (flow patterns, N-p, k(s)) are in line with previous work (experimental and simulation). (C) 2012 Elsevier B.V. All rights reserved.