(578a) The Taylor-Couette Disc Contactor, a Novel and Flexible Apparatus for High Throughput Liquid-Liquid Extraction

The Taylor-Couette Disc Contactor (TCDC) [1, 2] shows high potential for application in liquid-liquid extraction. This agitated counter currently operated extraction column makes use of the hydrodynamic advantages of the rotating disc contactor (RDC) and the Taylor-Couette reactor (TCR). The TCDC design is based on the design of the rotating disc contactor (RDC) but without stator rings and with increased shaft and disc diameter. The shaft diameter is increased to an optimum ratio of D_Column/D_Shaft=0.5 to prevent formation of hydrodynamic dead zones at the area of the shaft. The shaft and the discs induce banded two-phase flow similar to banded flow in the Taylor-Couette reactor. The simple design makes the TCDC insensitive to any kind of crud accumulation, and thus it becomes highly tolerant to varying quality of the feed streams. The simple design of internals allows high hydraulic load beyond B = 30 [m³ m^-2 h^-1]. For appropriate column design, the hydrodynamic design specification is required. Therefore, the effect of varying hydraulic load, rotational speed and phase ratio on the dispersed phase holdup, residence time distribution and drop size distribution was investigated in a 0.1 m and 0.3 m TCDC column. The total hydraulic load has a minor influence on the DSD. The effect of varying phase ratio on the dispersed phase holdup is insignificant at low hydraulic load. The effect of the phase ratio at high hydraulic load has a significant impact on dispersed phase holdup. Comparison of operation in 0.1 m and 0.3 m scale has proven CFD based simulation results of scale up rules, including the effect of varying rotor disc diameter on operation performance. Axial dispersion was determined by measuring the residence time distribution. The effect of varying rotor disc diameter on dispersed phase holdup, residence time distribution and drop size distribution was investigated to test the flexibility of this column design. The rotor disc diameter of the TCDC can be varied from design without discs (Taylor-Couette reactor) to a maximum rotor disc diameter of 90% of the column diameter. The total hydraulic load is hardly affected by the ratio of rotor disc diameter to column diameter. This makes the TCDC column easily adjustable to specific separation tasks.

[1] E. Aksamija, C. Weinländer, R. Sarzio, M. Siebenhofer, Sep. Sci. Technol. 2015, 50 (18), 2844–2852. DOI: 10.1080/01496395.2015.1085406

[2] A. Grafschafter, M. Siebenhofer, Chemie-Ingenieur-Technik 2017, 89 (4), DOI: 10.1002/cite.201600142