Liquid holdup and distribution in trickle beds with X-ray computed technology

Multiphase flows exist in many areas of commerce such as manufacture of petroleum-based products and fuels, the production of commodity and specialty chemicals, pharmaceuticals and pollution abatement (Al-Dahhan et al., 1997). Especially, randomly packed beds operated in gas-liquid concurrent down-flow mode in the trickling regime are widely used (e.g. catalytic hydrogenations and oxidations). The reactor behavior is very complex and depends strongly on the hydrodynamics as fundamental criteria for the selection and productivity of multiphase reactors and safety of processes (Krishna and Sie, 1994). Most important hydrodynamic aspects are the liquid holdup and the cross sectional liquid distribution. Two phase flow in randomly packed beds is difficult to visualize, characterize and quantify due to opaque systems, irregular nature and internal objects and structures. X-ray computed radiography (CR) and computed tomography (CT) is used to explore two phase flow in randomly packed beds.