(104a) Multi-Stage-Counter Current Rotating Packed Bed For Distillation

The development of new apparatuses and processes for the chemical and bio-based production is necessary to meet the global future challenges. The realization of highly efficient, flexible and innovative processes contributes to achieving these goals. Apparatuses for separation that potentially fulfill these requirements are phase contactors applying centrifugal force instead of gravitational force, so called HIGEE-apparatuses (“high gravity”). A promising example are rotating packed beds (RPBs), in which a torus shaped packing is rotating while the liquid (radially outward direction) and the vapor phase (radially inward direction) are contacted counter currently. The phase contact occurs in a centrifugal field with a multiple of the gravitational force. The high acceleration enables intense mixing, large interfacial areas and quick mass transfer between the phases. This gives the opportunity for high capacities at short residence times of the chemicals inside the heat exposed areas. Additionally, a flexible layout and orientation of the apparatus independently from the gravity as well as niche-applications, for example for highly viscous media, are enabled which cannot be distilled in conventional columns.

The aim of this work is to proove the feasibility and to quantify the separation efficiency of distillation processes in RPBs. For this purpose a Multi-Stage Counter-Current Rotating Packed Bed (MSCC-RPB) has been developed. This apparatus consists of three consecutive rotors mounted onto a single shaft. In between the rotors a liquid feed can be added to the apparatus to allow variation in the feed position. In the first step the hydrodynamics of the apparatus regarding pressure drop and flooding behavior of this novel type of RPBs have been characterized. Especially the flooding behavior has to be redefined compared to conventional columns since parameters such as superficial area, centrifugal acceleration and liquid and vapor loadings are strongly dependent on the radial position inside the rotor. In the second step distillation experiments with finite reflux ratio using an ethanol water mixture have been carried out to characterize the separation efficiency of the MSCC-RPB. The influence of the rotational speed, liquid and vapor loadings and feed position have been characterized.