Understanding the complex dynamics and spatial distribution of rising bubbles in fluidized bed gasifiers is crucial for designing, optimizing, and scaling up of the reactor. However, existing studies on bubble dynamics mainly focused on cold flow investigations, failing to capture the behavior of bubbles under the influence of chemical reactions and intricate coupling of heat transfer. Therefore, a reactive Lagrangian model is established to explore intricate bubble behaviors during biomass air gasification. The model is well validated with experiment, and the impact of operating parameters including bed temperature and equivalence ratio (ER) on the bubble behaviors is studied. The growth, coalescence, break, and eruption of rising bubbles are studied. A lower ER is recommended for better gasification performance. With an increase in the ER from 0.12 to 0.3, both the lower heating value and combustible gas concentration experienced a decrease of approximately 38.5% and 38.3%, respectively. The lateral feeding of biomass leads to asymmetrical distribution of bed temperature and bubble properties. Near the biomass inlet, a larger bubble aspect ratio is observed, possibly attributed to the hindrance in the lateral bubble growth due to the lateral biomass feeding. The bubble coordinate number is introduced to characterize the degree of bubble distribution density in a specific region. It is found that increasing the operating temperature results in a reduction in the density and an increase in the volume of bubbles at the bottom, resulting in a denser distribution of bubbles in this region. Although this concentrated bubble distribution may impact local heat and mass transfer, the differences in bubble distribution under temperature dominance gradually decrease along the reactor height. The impact of the operating conditions on the thermal properties and spatial distribution of bubbles obtained in this work can provide valuable guidance for practical gasification operations.

中文翻译：

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鼓泡流化床气化炉鼓风生物质气化气泡上升动力学的见解

了解流化床气化炉中上升气泡的复杂动力学和空间分布对于反应器的设计、优化和扩大规模至关重要。然而，现有的气泡动力学研究主要集中在冷流研究上，未能捕捉到气泡在化学反应和复杂的传热耦合影响下的行为。因此，建立了反应拉格朗日模型来探索生物质空气气化过程中复杂的气泡行为。该模型经过实验验证，并研究了床温和当量比（ER）等操作参数对气泡行为的影响。研究了上升气泡的生长、合并、破裂和喷发。建议使用较低的 ER 以获得更好的气化性能。随着ER从0.12增加到0.3，低热值和可燃气体浓度分别下降了约38.5%和38.3%。生物质的横向进料导致床温和气泡特性的不对称分布。在生物质入口附近，观察到较大的气泡纵横比，这可能是由于侧向生物质进料阻碍了侧向气泡生长。引入气泡坐标数来表征特定区域内气泡分布的密集程度。研究发现，提高操作温度会导致底部气泡密度降低和体积增加，导致该区域气泡分布更密集。尽管这种集中的气泡分布可能会影响局部传热和传质，但温度主导下气泡分布的差异沿着反应器高度逐渐减小。本工作中获得的操作条件对气泡的热性质和空间分布的影响可以为实际气化操作提供有价值的指导。