聚合物搅拌脱挥设备及其CFD模拟研究进展

Progress on agitated apparatus for polymer devolatilization and its CFD simulation

综述了聚合物搅拌脱挥设备的开发进展,分析了设备开发过程存在的关键问题。指出卧式脱挥设备中的流动特性、混合特性、成膜特性以及表面更新特性等是强化传质的关键因素,具有自清洁搅拌特性的高效卧式脱挥设备是装备开发与研究的主要方向。阐述了计算流体力学(CFD)在研究高黏流体卧式搅拌设备内传递过程机理中的应用。基于网格重叠技术的有限元方法和基于动网格的有限体积方法可以解决复杂几何结构的桨叶和翅片、双轴的旋转运动以及啮合机构非常小的间隙等难题。借助于CFD中VOF多相流模型可以精确地追踪气液相界面,模拟反应器中的成膜过程和表面更新特性,进而可以深入分析设备中的传质过程,为高效聚合物脱挥设备的优化与设计提供了新的思路。

The progress on new types of agitated apparatus for polymer devolatilization was reviewed,while the key issues on the development of new devolatilization devices were analyzed. The characteristics of flow field,mixing,film forming and surface renewal are the key factors to strengthen the mass transfer process. Developing highly efficient and self-cleaning devices for polymer devolatilization is the major prospect in this field. The applications of computational fluid mechanics（CFD） simulations on transfer process in such devices were also discussed. Finite element method combined with mesh superposition technique（MST） and finite volume method combined with dynamic mesh technique have been used to deal with problems such as complex geometric blades and fins,twin-shaft rotating motion,tiny gaps within engaged areas and so on. Gas-liquid interface can be precisely tracked by means of volume of fluid（VOF） multiphase flow model. The film forming and surface renewal characteristics can be investigated,which contributes to learn more about the mass transfer mechanism. CFD numerical simulation offers a new idea for designing highly efficient devices for polymer devolatilization.