Stable and controllable solid flow is essential in circulating fluidized bed (CFB) systems. The L-valve is a typical non-mechanical valve that can provide flexible solid feeding. The investigation of the solid circulation rate and the hydrodynamic characteristics of the L-valve is crucial to its design and operation. The gas-solid flow in the L-valve of a full-loop CFB is studied with the coarse-grained discrete particle method (EMMS-DPM). Good agreements on the solid circulation rate and the pressure drop through the L-valve are achieved between the simulated and experimental data. The solid circulation rate increases linearly with the aeration velocity until the stable particle circulation of the CFB is destroyed. The flow patterns in the horizontal section of L-valve are gas-solid slug flow above the stationary solid layer and the moving solid layer, respectively. The effects of L-valve geometric parameters on the solid flow characteristics are also investigated. The results indicate that reducing the diameter and length of the horizontal section of L-valve can improve the solid transport efficiency, especially at low aeration velocity. Besides, the solid conveying capacity and flow stability are improved when the sharp bend of L-valve is modified to be a gradual bend.

中文翻译：

---

循环流化床L阀的粗粒离散粒子法模拟

稳定且可控的固体流对于循环流化床 (CFB) 系统至关重要。 L型阀门是一种典型的非机械阀门，可以提供灵活的固体进料。 L型阀的固体循环速率和流体动力特性的研究对其设计和运行至关重要。采用粗粒离散粒子法（EMMS-DPM）研究全回路循环流化床L阀内的气固流动。模拟数据和实验数据在固体循环速率和通过 L 阀的压降方面取得了良好的一致性。固体循环速率随着曝气速度线性增加，直到CFB的稳定颗粒循环被破坏。 L阀水平截面内的流型分别为静止固体层和运动固体层上方的气固段塞流。还研究了 L 阀几何参数对固体流动特性的影响。结果表明，减小L阀水平段的直径和长度可以提高固体输送效率，特别是在低曝气速度下。此外，将L型阀的急弯改为渐变弯，固体输送能力和流动稳定性得到提高。