No abstract

The use of bubble columns in industry is widespread, as the columns are relatively cheap to install, run and maintain. Bubble columns are also excellent tools for the transfer of gas phase components into the liquid phase, as the gas provides a source of mass and energy to the liquid. The study of the flow regimes in bubble column involves the use of experimental techniques and computational fluid dynamics (CFD). The application of CFD techniques has produced notable developments, but the validation of such codes is not easy as experimental techniques give a limited representation of flow phenomena present. The methods developed include the volume of fluid methods, dispersed phase models, Eulerian two-fluid models, and the algebraic slip mixture models. The aim of this paper is to track the motion of particles that represent support beads used in gas-liquid-solid biological reactors using a commercially available computational fluid dynamics package (FLUENT). Gas-liquid interactions were modelled using an algebraic slip mixture model with the standard k-e turbulence model in two dimensions for a bubble column with an aspect ratio of 5:1. A superficial gas velocities of 0.02 0.05, 0.10, 0.15 m s -1 to provide buoyant motion in the column. Particles were injected into the flow regime and generally followed the motion of the vortical structures present. A method was used to assess the direction of motion of the particles travelling within the column. Comparisons of the fluid phenomena and the motion of particles where made between simulation and experiment. This work is funded by the European Community Inco-Copernicus Fund Contract No. IC15-CT98-0904 as a group of European Universities, that is intending to improve the understanding of flow-regimes in three-phase bio-chemical processes in bubble columns and airlift reactors.Dynamic models of an catalytic three-phase slurry reactor are developed to examine numerically transient axial temperature and concentration profiles obtained for the hydrogenation of o-cresol on Ni/SiO 2 catalyst. These non-isothermal heterogeneous models include the resistences to heat and mass transfer at the gas-liquid and liquid-solid interfaces, consider (or may not consider) the resistances inside the catalyst particle, as well as the heat exchange through the jacket of the reactor. The predictions of the models describe dynamic events, such as the effects of sudden changes in the operating conditions on the reactor behaviour and its thermal stability. The models allowed to reproduce the main characteristics of the reactor dynamic behaviour, which are in agreement with the literature. 526*Precipitation of Sulfur Dioxide by Absorption with Sulfuric Acid: Investigation of Mass Transfer in a Falling-Film Absorption Column M . V o r b a c h 1 R . M a r r 1 M . S i e b e n h o f e r 2

No abstract