Accurate prediction of gas-solid flow hydrodynamics is key for the design, optimization, and scale-up of a circulating fluidized bed (CFB) reactor. Computational fluid dynamics (CFD) simulation with two-dimensional (2D) domain has been routinely used, considering the computational costs involved in three-dimensional (3D) simulations. This work evaluated the prediction capability of 2D and 3D gas-solid flow simulation in the lab-scale CFB riser section. The difference between 2D and 3D CFD simulation predictions was assessed and discussed in detail, considering several flow variables (superficial gas velocity, solid circulation rate, and secondary air injection). The transient Eulerian-Eulerian multiphase model was used. CFD simulation results were validated through an in-house experiment. The comparison between the experimental data and both computational domains shows that the 3D simulation can accurately predict the axial solid holdup profile. The CFD simulation comparison considering several flow conditions clearly indicated the limitation of the 2D simulation to accurately predict key hydrodynamic features, such as high solid holdup near the riser exit and riser bottom dense region. The accuracy of 2D and 3D simulations was further assessed using root-mean-square error calculation. Results indicated that the 3D simulation predicts flow behavior with higher accuracy than the 2D simulation.

中文翻译：

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各种操作条件下 CFB 反应器中气固流的实验和多相 CFD 模拟：评估 2D 和 3D 模拟的性能

准确预测气固流动流体动力学是循环流化床 (CFB) 反应器设计、优化和放大的关键。考虑到三维 (3D) 模拟中涉及的计算成本，已常规使用二维 (2D) 域的计算流体动力学 (CFD) 模拟。这项工作评估了实验室规模 CFB 立管段中 2D 和 3D 气固流动模拟的预测能力。考虑到几个流动变量（表观气体速度、固体循环速率和二次空气注入），详细评估和讨论了 2D 和 3D CFD 模拟预测之间的差异。使用瞬态欧拉-欧拉多相模型。通过内部实验验证了 CFD 模拟结果。实验数据与两个计算域之间的比较表明，3D 模拟可以准确地预测轴向固含量分布。考虑几种流动条件的 CFD 模拟比较清楚地表明 2D 模拟在准确预测关键流体动力学特征方面的局限性，例如立管出口附近的高固含量和立管底部密集区域。使用均方根误差计算进一步评估 2D 和 3D 模拟的准确性。结果表明，3D 模拟比 2D 模拟更准确地预测流动行为。考虑几种流动条件的 CFD 模拟比较清楚地表明 2D 模拟在准确预测关键流体动力学特征方面的局限性，例如立管出口附近的高固含量和立管底部密集区域。使用均方根误差计算进一步评估 2D 和 3D 模拟的准确性。结果表明，3D 模拟比 2D 模拟更准确地预测流动行为。考虑几种流动条件的 CFD 模拟比较清楚地表明 2D 模拟在准确预测关键流体动力学特征方面的局限性，例如立管出口附近的高固含量和立管底部密集区域。使用均方根误差计算进一步评估 2D 和 3D 模拟的准确性。结果表明，3D 模拟比 2D 模拟更准确地预测流动行为。