Achieving high volatiles conversion is crucial to biomass chemical looping combustion. Challenges arise from rapid devolatilization of biomass and limited biomass injection ports, resulting in volatiles with insufficient contact with oxygen carriers in fluidized beds. A concept called volatiles distributor (VD) has recently been proposed and investigated in a cold-flow fluidized bed, which shows excellent performance in achieving an even distribution of volatiles over the cross section. To deeply understand VD's impact on hydrodynamics behaviors, pioneering three-dimensional full-loop cold-flow CFD simulations were conducted using an Eulerian multiphase granular model. Three drag models, i.e., Gidaspow, Filtered, and two-step EMMS/bubbling, were evaluated against experimental data. While all models perform well in bubbling fluidization, the two-step EMMS/bubbling model excels in turbulent fluidization. Additionally, CFD simulations reveal improved mixing between volatiles and bed materials with VD, highlighting its efficiency in addressing incomplete conversion of high-volatile fuels like biomass in fluidized bed systems.

中文翻译：

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用于生物质化学链燃烧的带有挥发物分配器的流化床的 CFD 建模


实现高挥发物转化率对于生物质化学循环燃烧至关重要。生物质的快速脱挥发分和有限的生物质注入口带来了挑战，导致挥发物与流化床中的氧载体接触不充分。最近提出了一种称为挥发物分配器（VD）的概念，并在冷流流化床中进行了研究，该概念在实现挥发物在横截面上的均匀分布方面表现出优异的性能。为了深入了解 VD 对流体动力学行为的影响，使用欧拉多相颗粒模型进行了开创性的三维全循环冷流 CFD 模拟。根据实验数据评估了三种阻力模型，即 Gidaspow、过滤和两步 EMMS/冒泡。虽然所有模型在鼓泡流化方面均表现良好，但两步 EMMS/鼓泡模型在湍流流化方面表现出色。此外，CFD 模拟揭示了 VD 改善了挥发物和床材料之间的混合，突显了其在解决流化床系统中生物质等高挥发性燃料不完全转化问题方面的效率。