Abstract

Hydrodynamics of stirred vessel is difficult to predict due to complex flow conditions existing inside the reactor. Hence in this present work, hydrodynamics and solid suspension in a continuous stirred vessel are numerically investigated using Computational Fluid Dynamics (CFD). To predict the flow field, transient 3 D CFD simulations are performed using Multiple Reference Frame along with Sliding Mesh approach and realizable k-ε turbulence model. The flow field is quantified by spatial/temporal variation of liquid velocity magnitude and liquid circulation. To improve the performance of the stirred vessel, draft tube baffle configurations are proposed and these predictions are compared with the unbaffled system. Further, the suspension characteristics of solids are predicted using the Euler-Granular model and quantified by calculating cloud height in stirred vessel system. The solid concentration is found to be uniform in the baffled stirred vessel and it is concentrated at the bottom of the vessel in the unbaffled stirred vessel. Thus, the proposed draft tube configuration supports in achieving the uniform distribution of solids and overcomes sedimentation of solids in stirred vessel system.

摘要

由于反应器内部存在复杂的流动条件，搅拌容器的流体动力学难以预测。因此，在目前的工作中，使用计算流体动力学 (CFD) 对连续搅拌容器中的流体动力学和固体悬浮液进行了数值研究。为了预测流场，瞬态 3D CFD 模拟使用多参考框架以及滑动网格方法和可实现的 k-ε 湍流模型进行。流场通过液体速度大小和液体循环的空间/时间变化来量化。为了提高搅拌容器的性能，提出了导流管挡板配置，并将这些预测与无挡板系统进行了比较。更远，使用 Euler-Granular 模型预测固体的悬浮特性，并通过计算搅拌容器系统中的云高进行量化。发现固体浓度在带挡板的搅拌容器中是均匀的，并且在不带挡板的搅拌容器中集中在容器底部。因此，所提出的引流管配置支持实现固体的均匀分布并克服了搅拌容器系统中固体的沉降。