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

Abstract

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–ε model. First results without basket showed a good agreement between simulations and literature, by comparing impeller power numbers (Np) 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 (ks) 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, Np, ks) are in line with previous work (experimental and simulation).