Numerical investigation of cold fluidization behavior using a dual-size Eulerian model (DSEM): Effects of particle size on hydrodynamics in fluidized bed reactors

초록

Hydrogen-based fluidized bed reactors have emerged as a promising pathway for decarbonizing the steelmaking industry, but their operational stability is often affected by factors such as particle sticking, dust loss, and uneven residence time. Since these issues are related to particle size distribution, accurate modeling that incorporates particle size effects is essential. In this study, a Dual-Size Eulerian Model (DSEM) was developed to simulate cold fluidization using two representative particle sizes. The model was validated against experimental measurements of pressure drop and solid holdup, demonstrating improved predictive capability compared with the conventional single-size model. Specifically, the DSEM reduced the root mean square error of solid holdup by 56% and enhanced pressure-drop prediction accuracy by 7%. Furthermore, mean peak difference analysis revealed that the DSEM achieved 67% closer agreement with experimental amplitude characteristics than the single-size model. Beyond quantitative accuracy, the DSEM successfully captured size-dependent fluidization behaviors, including particle segregation and entrainment, which the single-size model failed to resolve. Detailed analysis showed that these phenomena induce local flow regime separation and influence pressure fluctuations. Based on these insights, new indicators for stable reactor operation and a refined criterion for selecting representative particle sizes were proposed. These findings highlight DSEM's effectiveness in analyzing complex fluidized bed systems and advancing low-carbon steelmaking technologies.

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