Three-dimensional CFD simulation of tapered gas-solid risers by coupling the improved EMMS drag
Three-dimensional CFD simulation of tapered gas-solid risers by coupling the improved EMMS drag
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DOI：
10.1016/j.powtec.2019.04.070
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发表时间：
2019-06
影响因子：
5.2
通讯作者：
Xinhua Liu;M. Zhao;Sha Hu;W. Ge
中科院分区：
文献类型：
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作者：
Xinhua Liu;M. Zhao;Sha Hu;W. Ge
为了适应各种反应的要求，锥形气固立管在一些工业过程中得到了应用，但在以往的研究中对这种反应器的关注很少。在这项工作中，采用基于EMMS模型的改进结构相关阻力的双流体模型，模拟了锥形和锥形立管中的三维气固流动。在不同的轴向水平上求解EMMS模型，以确定非均质指数与空隙的不同相关性，然后在这些水平之间进行插值，以改进对锥形立管间相阻力变化的预测。考虑到EMMS阻力的轴向变化，与平均EMMS阻力或均匀阻力规律相结合，模拟预测了锥形立管内的流动动力学更为合理。详细讨论了锥形立管内的轴向和径向非均质性以及参数对流动动力学的影响，为锥形气固立管反应器的合理设计提供参考。
Tapered gas-solid risers have been used in some industrial processes in order to adapt to the requirements of various reactions, but little attention was paid to these reactors in previous investigation. In this work, three-dimensional gas-solid flow in tapered-out and tapered-in risers was simulated by the two-fluid model using an improved structure-dependent drag based on the EMMS model. The EMMS model was solved at different axial levels to determine different correlations of heterogeneity index with voidage, which were then interpolated between these levels to improve the prediction of varying interphase drag in the tapered risers. Considering the axial variation of the EMMS drag, the simulation predicts much more reasonable flow dynamics in the tapered risers than those coupled with an average EMMS drag or homogeneous drag laws. The axial and radial heterogeneities as well as the parametric effects on the flow dynamics in the tapered risers were discussed in detail, so as to provide reference for the proper design of tapered gas-solid riser reactors.