Backmixing Characterization of a Bubble Column with Short Venturi Throats by Multipoint Internal Tracer Injections

Abstract

In reduction of liquid backmixing in bubble columns, Wu et al. [Wu, Y; Cheng, Z. M.; Huang, Z. B. Backmixing reduction of a bubble column by interruption of the global liquid circulation. Ind. Eng. Chem. Res. 2009, 48, 6558− 6563] have shown that the backmixing could be substantially reduced by interrupting the global liquid circulation using four identical short Venturi throats (SVTs). Considering the advantages of such structures, it is necessary to further investigate the backmixing characteristics of a bubble column with SVTs. In the present work, a multipoint tracer injection and detection device was employed to enhance the insight into where and how the liquid tracer was backmixed in different stages of a 50-cm diameter column. Tracer response profiles were measured to track the liquid backmixing trajectory in different stages at various operating conditions. The results showed that the backmixing of the column was sensitive to the throat diameter of SVTs. Based on the observed physical phenomena, a tanks-in-series with backflow (TISB) model was adopted to interpret the tracer experiment data, which shows an excellent agreement between the prediction and experimental measurements.

Bubble Size “Bimodal” Distribution Enhances Mixing and Mass Transfer in Slurry Bubbling Column Reactor

“…Take the 30 g/L KCl solution as the tracer and inject the tracer into the SBCR by switching the bypass. The influence of bubbles can be eliminated by additional screen mesh and drainage devices . In this experiment, the drainage device was adopted considering that the microbubbles are very difficult to completely block by a mesh.…”

“…The influence of bubbles can be eliminated by additional screen mesh and drainage devices. 32 In this experiment, the drainage device was adopted considering that the microbubbles are very difficult to completely block by a mesh. The liquid was drawn from the SBCR and sent to a small gas−liquid separation device, and the conductivity electrode (DJS-1D, LEICI, China) and conductivity meter (DDS-307, LEICI, China) were used to measure the change in the conductivity of the liquid.…”