Hydrodynamics and solid liquid contacting effectiveness in an upflow multiphase reactor

Experimental runs were carried out in a fixed bed upflow pilot reactor to investigate the hydrodynamics of the liquid phase. Three kinds of packing were used: 3 × 3 mm glass cylinders, 3 × 4 mm alumina cylinders and 1.7 × 4 mm alumina extrudates. A tracer injection technique was used and the dynamic responses were interpreted using three different models: the axial dispersion model (PD), the stagnant zones model (PE) and the axial dispersion and stagnant zones model (PDE). Solid-liquid contacting effectiveness was evaluated by measuring the apparent intraparticle diffusivities of porous particles in the presence of the gas-liquid flow. The experimental results led to the following conclusions: (a) the axial dispersion model (PD) is not able to give a satisfactory interpretation of liquid hydrodynamics; (b) the flow map of upflow multiphase reactors is not yet well enough defined, especially for small size packings; (c) the estimate of the pressure drop by correlations in the literature is sufficiently good; (d) solid-liquid contacting effectiveness is higher, on average, than in trickle-bed reactors, but it decreases with an increase in gas flow rate.