Purpose

The purpose of this paper is to perform the computational fluid dynamics (CFD) simulation with experimental validation to investigate the particle segregation effect in abrupt and smooth shapes circulating fluidized bed (CFB) risers.

Design/methodology/approach

The experimental investigations were carried out in lab-scale CFB systems and the CFD simulations were performed by using commercial software BARRACUDA. Special attention was paid to investigate the gas-particle flow behavior at the top of the riser with three different superficial velocities, namely, 4, 6 and 7.7 m/s. Here, a CFD-based noble simulation approach called multi-phase particle in cell (MP-PIC) was used to investigate the effect of traditional drag models (Wen-Yu, Ergun, Wen-Yu-Ergun and Richardson-Davidson-Harrison) on particle flow characteristics in CFB riser.

Findings

Findings from the experimentations revealed that the increase in gas velocity leads to decrease the mixing index inside the riser. Moreover, the solid holdup found more in abrupt riser than smooth riser at the constant gas velocity. Despite the more experimental investigations, the findings with CFD simulations revealed that the MP-PIC approach, which was combined with different drag models could be more effective for the practical (industrial) design of CFB riser. Well agreement was found between the simulation and experimental outputs. The simulation work was compared with experimental data, which shows the good agreement (<4%).

Originality/value

The experimental and simulation study performed in this research study constitutes an easy-to-use with different drag coefficient. The proposed MP-PIC model is more effective for large particles fluidized bed, which can be helpful for further research on industrial gas-particle fluidized bed reactors. This study is expected to give throughout the analysis of CFB hydrodynamics with further exploration of overall fluidization.

中文翻译：

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CFB立管中三维CFD模拟和颗粒偏析的实验验证

目的

本文的目的是通过实验验证来执行计算流体动力学（CFD）模拟，以研究突然而光滑的循环流化床（CFB）立管中的颗粒偏析效果。

设计/方法/方法

在实验室规模的CFB系统中进行了实验研究，并使用商业软件BARRACUDA进行了CFD模拟。要特别注意研究立管顶部具有三种不同的表观速度（即4、6和7.7 m / s）的气体颗粒流动行为。在这里，使用基于CFD的高贵模拟方法（称为单元中多相颗粒（MP-PIC））来研究传统阻力模型（Wen-Yu，Ergun，Wen-Yu-Ergun和Richardson-Davidson-Harrison）的效果CFB立管颗粒流动特性的研究

发现

从实验中发现，气体速度的增加导致立管内部混合指数的降低。此外，在恒定气体速度下，突然上升管中的固体滞留量比平滑上升管中的滞留量更多。尽管进行了更多的实验研究，但CFD模拟的结果表明，结合不同阻力模型的MP-PIC方法对于CFB立管的实用（工业）设计可能更有效。在模拟和实验输出之间找到了很好的一致性。将仿真工作与实验数据进行了比较，实验结果吻合良好（<4％）。

创意/价值

在这项研究中进行的实验和模拟研究构成了具有不同阻力系数的易于使用的产品。所提出的MP-PIC模型对于大颗粒流化床更有效，这有助于进一步研究工业气-颗粒流化床反应器。预期该研究将提供对CFB流体动力学的整个分析，以及对整体流化的进一步探索。