(82a) Multiphase operations in the Taylor-Couette Disc Contactor

Multiphase reactions on industrial scale provide access to efficient and economical production of bulk chemicals. Nevertheless, the selection of reactor types is small and the modeling of fluid mechanical phenomena with more than two phases is difficult. This study focusses on the investigation and application of multiphase operations in the Taylor-Couette Disc Contactor (TCDC). The hydraulic characteristics and scalability have been investigated and confirmed [1]. It has been shown that the TCDC can continuously manage up to 4 phases simultaneously. Phase combinations are investigated by determining the holdup of dispersed phases and residence time distribution related to the rotating speed of the shaft and volumetric flowrate of phases. The TCDC is best modelled with the continuously stirred tank reactor cascade model. The results of selected phase combinations and their application will be presented. Continuous liquid-liquid-solid contact was successfully validated with the example of heterogeneously catalyzed esterification of acetic acid in aqueous solution and simultaneous extraction of the ester into the solvent phase, raising the total equilibrium conversion from 15% (without extraction) to 30%. Esterification experiments were performed and based on this data a reactor design algorithm was developed. To demonstrate the applicability of the Taylor-Couette Disc Contactor in gas-liquid operations continuous countercurrent neutralization of 0.1 molar sodium hydroxide solution with carbon dioxide was performed. The neutralization reaction was investigated for different rate of rotation, temperature and gas flowrate. Reaction rate and process efficiency were modeled based on film theory combined with a continuously stirred tank cascade approach. Neutralization of sodium hydroxide was performed until pH 9 was obtained to ensure neutralization reaction over the full reactor height. The experimental results confirm stable operation of the Taylor-Couette Disc Contactor in gas-liquid reactions. A simple column design algorithm for application in waste water neutralization with carbon dioxide is available. The hydraulics of four phase flow was investigated and confirmed. Applicability has not yet been confirmed, but will be some kind of heterogeneously catalyzed gas-liquid reaction with liquid-liquid phase transfer.

[1] A. Grafschafter, (2019), Simple and Effective: The Taylor-Couette Disc Contactor for liquid-liquid extraction (Design and Performance), PhD Thesis, TU Graz