CFD-DEM simulation of bubble dynamics and hydrodynamics in fluidized beds with louver baffles

Abstract

Fluidized beds are commonly used equipment in the chemical industry, but large bubbles might be generated, which lower the conversion efficiency and operational stability. To address this issue, internal components (e.g., louver baffles) can be employed to improve fluidization performance. Considering that the interaction between louver baffles and fluidized particle flows is quite complex, and the deploy settings would greatly influence the fluidization, further understanding is needed. The objective of this study is to investigate the effects of baffle inclination angle and superficial velocity on bubble dynamics and hydrodynamics in fluidized beds equipped with multi-layer louver baffles using computational fluid dynamics coupled with the discrete element method (CFD-DEM). Simulation results reveal that increasing superficial velocity in the baffle-free bed aggravates slug formation and deteriorates particle mixing. In contrast, the introduction of louver baffles effectively promotes bubble breakup and suppresses these phenomena, reducing the maximum average equivalent bubble diameter from approximately 140 mm to 31 mm. Baffles with 45° inclination generate the most uniformly distributed small spherical bubbles. As the inclination angle increases, particle downward motion becomes more pronounced, which induces local dilute regions and leads to an increase in bubble size. Notably, at low superficial velocities, steeper baffles with inclination angles of 55° and 60° may instead induce increased instability in the fluidized bed. These findings provide guidance for the design and optimization of baffled fluidized beds.