搅拌槽内中高黏物系的气液分散特性研究进展

从实验和数值模拟两方面对搅拌槽内中高黏物系条件下的气含率、气泡尺寸大小和传质特性等进行综述。讨论了搅拌桨型、操作条件、黏度或非牛顿性对气液分散特性的影响。阐明了径流式搅拌桨和上翻式轴流桨的组合能减小气穴,更适合中低黏物系的搅拌;搅拌转速比通气量的影响效果更明显,转速增加使气泡的分布均匀性变好,而提高通气速度会产生大气泡,使气泡分布不均匀程度增加;黏度或非牛顿性的增加可以改变气泡的碰撞频率,气泡平均尺寸减小。最后讨论了针对中高黏物系的计算流体力学模型的修正方法,并且展望了此领域的研究发展方向。

Research progress of gas dispersion in stirred vessel with medium or high viscosity fluids

Research progress of air hold-up,bubble size distribution and gas-liquid mass transfer in stirred vessel with viscous fluid were summarized from the perspective of experiment and simulation.The influences of impeller,operating conditions,viscosity or non-Newtonian characteristics on gas dispersion were discussed.The combination of radical-flow impellers and up-pumping axial impellers could decrease the scale of air cavitation,and was suitable for low viscosity and moderately viscous fluids.The influence of agitation speed was more significant than air inflation rate.With increasing agitation speed,uniformity of bubble distribution became better.Increasing air inflation rate enhanced air hold-up occupied by big bubbles.The non-uniformity of air distribution became worse.Increasing viscosity or non-Newtonian capacity changed the rate of collision of bubbles,making mean bubble size smaller.Correction of computational model for viscous fluids was presented and the direction of future research was prospected.