FLUID-FLOW THROUGH CATALYST FILLED TUBES

A detailed knowledge of the fluid flow profile is essential for a prop er design of fixed-bed processes. For different sphere, ring and cylin der sizes, radial velocity profiles were measured below the bed at emp ty tube velocities of air of 0.5 m/s < v(0) < 1.5 m/s and the tube-to- particle diameter ratios 3.3 < d(t)/d(p) < 11. The profiles show a vel ocity maximum in the vicinity of the wall. As a consequence of the sta tistical behaviour of packings, it was necessary to average velocity m easurements after repacking in order to obtain representative flow pro files. These averaged profiles were the basis for a model through whic h the flow profile inside the packing can be calculated for spheres, c ylinders and rings. The model is based upon the extended Brinkman equa tion and the independently determined radial void fraction profiles. I t considers an 'effective viscosity' for which correlations have been derived. Comparison of simulated velocity profiles with exemplary liqu id flow measurements inside the packed bed of Vortmeyer and co-workers shows reasonable agreement. (C) 1997 Elsevier Science Ltd.