Suspension quality and power consumption of the complex multiphase flow field in a draft-tube stirred reactor--颗粒学报PARTICUOLOGY

Wang, L., Tian, Y., Qi, Y., Gao, Y., & Wang, M. (2021). Suspension quality and power consumption of the complex multiphase flow field in a draft-tube stirred reactor. Particuology, 56, 91-102. https://doi.org/10.1016/j.partic.2020.10.008

Suspension quality and power consumption of the complex multiphase flow field in a draft-tube stirred reactor

Licheng Wang ^*, Yanxing Tian, Yu Qi, Yiwei Gao, Mengya Wang

School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, China

10.1016/j.partic.2020.10.008

Volume 56, June 2021, Pages 91-102

Received 29 July 2020, Revised 5 October 2020, Accepted 20 October 2020, Available online 13 November 2020, Version of Record 8 March 2021.

E-mail: wangch586@email.tjut.edu.cn

Highlights

• The liquid–solid–solid system in a draft-tube stirred reactor is investigated.

• The CFD model is verified by the experimental concentration distribution.

• The influence of the draft tube on the flow field is studied.

• The suspension is evaluated using the concentration standard deviation.

• Power consumption of a flow field with a draft tube is lower.

Abstract

Experiment and simulation were used to study the flow fields of a liquid–solid–solid three-phase system in a draft-tube stirred reactor with a six-flat-bladed turbine impeller (BT) and a 45° pitched six-bladed upflow turbine impeller (PBTU45). The computational fluid dynamics (CFD) formulation was based on a 3D Eulerian multi-fluid model along with a renormalization group (RNG) k-ε turbulence model, which took into account the inter-phase momentum exchange between different phases. The CFD model was validated using experimental data, and the suspension quality was validated by determining the standard deviation of the solid concentration. Good solid suspension was achieved in flow fields agitated by the BT impeller at low impeller speeds. The draft tube adversely affected solid dispersion at most impeller speeds. In flow fields agitated by the PBTU45 impeller, good solid suspension required a faster impeller speed. The suspension quality with the draft tube was better than that without the draft tube under most operating conditions. The power consumption of the BT or PBTU45 impeller with the draft tube was less than that without the draft tube at most impeller speeds.

Graphical abstract

Keywords

Liquid–solid–solid; Stirred reactor; Draft tube; Computational fluid dynamics; Power consumption; Suspension quality

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