Hydrodynamic characterization of an inclined rotating fixed bed reactor using tomographic imaging

Trickle bed reactors with liquid and gas phase flowing cocurrently downwards at moderate superficial velocities are widely used, e. g. for selective hydrogenation, processing of volatile organic compounds or wastewater treatment [Duduković et. al., 2010]. This reactor type, however, has inherent disadvantages like liquid maldistribution and hence, imperfect wetting of the packing. Furthermore, mass transfer limitations of the gas phase to the active sites of the catalyst through liquid films at the packing surface are another shortcome.

As a new process intensification concept, an inclined fixed bed reactor with superimposed rotation that allows a spatial periodic operation at constant gas and liquid flow rates is proposed. The packing is periodically immersed into the liquid phase that accumulates mainly in the lower part of the reactor cross-section. Inclination angle and rotational speed provide additional degrees of freedom to adjust liquid residence time and periodicity of wetting and draining, respectively.

The present work aims to study the hydrodynamics, i. e. dynamic liquid holdup and pressure drop, in the new reactor concept. These studies comprise variations of reactor inclination (α = 15° - 90°), rotational speed (up to 60 rpm) as well as gas (vG = 0.025 m/s - 0.05 m/s) and liquid (vL = 0.01m/s - 0.05 m/s) superficial velocities. Additional variations, e.g. of packing and packing particle size, liquid viscosity and liquid (water, silicone oil, cumene) will be reported.
The experimental setup consists of a tubular reactor (ID = 0.1 m, L = 1.2 m) with rotary unions. The whole reactor is supported by rollers, driven by a hollow shaft rotary actuator and mounted in an inclinable frame. The gas-liquid distribution patterns are visualized by means of a noninvasive compact γ-ray computer tomography system (CompaCT), which is mounted in the same frame on a rotary stage. The spatial in-plane resolution of the measurement system is 2 mm. The applicability of γ-ray CT for hydrodynamic investigations in packed bed reactors has been demonstrated recently [Bieberle et. al., 2010].

References
1. Bieberle, A., M. Schubert, M. J. da Silva, and U. Hampel, Ind. Eng. Chem. Res., 49, 9445-9453 (2010).
2. Duduković, M. P., F. Larachi, and P. L. Mills, Catal. Rev., 44, 123-246 (2002).