Coaxial Flow Contactors as Alternative to Double T‐Contactors for Triphasic Slug Flow Generation

Abstract

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.Triphasic gas-liquid-liquid slug flow systems have great application potential in flow chemistry and are normally generated with a double T-junction where the continuous phase and one disperse phase form a two-phase flow and the second disperse phase is added at the second junction. This design is limited to high disperse phase ratios when a regular and uniform flow is desired. The use of coaxial contactors allows overcoming most of these restrictions. The slug generation, stability, and regularity of the generated triphasic flow were experimentally characterized.

Photoelectric Sensor for Fast and Low-Priced Determination of Bi- and Triphasic Segmented Slug Flow Parameters

“…To generate a stable and uniform triphasic flow, as described by Hellmann et al, two coaxial slug generators are placed in series [4]. By varying the position of the inner capillary in these coaxial slug generators, the bubble lengths can be adjusted reproducibly, flexibly, and independently of the volumetric flow rates and phase ratios [28].…”

“…Microcapillary reactors with segmented slug flow exhibit excellent behavior in such multiphase systems. Segmented slug flow has been extensively studied in circular capillaries (≤1 mm inner diameter) [2][3][4][5][6][7][8]. Each phase involved forms a regular, stable segment within a uniform alternating sequence, where a bubble is defined as a droplet and a slug as the continuous phase between two bubbles, both with an axial length greater than its diameter.…”

“…In addition, the small dimensions and internal circulations intensify the transport phenomena. Segmented slug flow can be generated for biphasic liquid/liquid and liquid/gas systems or even triphasic liquid/liquid/gas systems [4]. To summarize, the segmented slug flow in capillary reactors seems to offer a promising alternative to conventional multiphase unit operations [9].…”

“…The approach of using double transmissive sensors as a sensor system for slug flows appears to be one of the most effective and economical ways to detect slug-flow characteristics. In light of recent research on three-phase slug flows, the sensor system is extended from two-phase to encompass three-phase flows in this work [2,4,27]. In this context, the influence of capillary position relative to the photodetector is also examined, since an improvement in the discrimination between the individual phases is expected as a function of the light refraction.…”