Effect of continuous single bubble injection on binary mixtures in a fluidized bed--颗粒学报PARTICUOLOGY

Process Design and Simulation Research Centre, School of Chemical Engineering, College of Engineering, University of Tehran, P. O. Box 11155-4563, Tehran, Iran

10.1016/j.partic.2025.02.025

Volume 100, May 2025, Pages 62-77

Received 2 August 2024, Revised 10 February 2025, Accepted 24 February 2025, Available online 15 March 2025, Version of Record 22 March 2025.

E-mail: sotudeh@ut.ac.ir

Highlights

• Investigating bubble shape and diameter in rod-sphere mixtures using CFD-DEM.

• Demonstrating enhanced mixing through continuous bubble injection.

• Optimizing gas usage for efficient particle mixing in binary systems.

• Revealing improved mixing with increased rod-like particle content.

Abstract

In this study, single bubbles are injected into a binary mixture comprising both spherical and rod-like particles to explore bubble shape and diameter. Effect of continuously injecting bubbles into a fluidized bed at a velocity near the minimum fluidization velocity on mixing is investigated. The combination of computational fluid dynamics and discrete element methods (CFD-DEM) as well as an experimental setup were used to investigate the mixing of particles in this situation. The rod-like particles were modeled by multi-sphere method. To assess the mixing performance, both qualitative and quantitative measures were employed, including visual examination of fluidized beds and evaluating subdomain-based mixing index. It was shown that the continuous injection of single bubbles can significantly improve mixing compared with the case of no bubble injection. Furthermore, when the number of rod-like particles increases, the continuous injection of single bubbles is an effective technique for improving mixing. In processes where gas utilization is critical and cost optimization is paramount, continuous injection of bubbles can reduce the gas volume required. This method is particularly beneficial in industries where high gas volumes are impractical or require significant equipment changes. It also helps break down dead zones and channeling phenomena in fluidized beds, especially when rod-like particles are present.

Graphical abstract

Keywords

CFD-DEM; Subdomain-based mixing index; Mixing; Bubble injection

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