【作者】 张国娟；

【导师】 高正明；

【作者基本信息】 北京化工大学 ， 化学工程， 2004， 硕士

【摘要】 搅拌槽反应器广泛应用于许多工业过程，混合时间是搅拌反应器设计的重要参数。国内外采用计算流体力学（CFD）对混合时间进行理论研究的文献相对较少。本文应用CFD软件FLUENT，选用多重参考系法（MRF）及标准k－ε模型，采用将速度场与浓度场方程分开进行求解方法，在直径为Φ0.476m的搅拌槽内，采用标准六直叶涡轮和CBY轴流式翼形桨，分别对两种桨型的单层和双层桨搅拌槽内的混合过程进行了数值模拟。对于单层桨体系，不论是六叶直涡轮还是CBY翼形桨，混合时间的模拟值与实验结果吻合良好；对于双层桨体系，双层CBY桨混合时间的模拟值与实验结果相吻合，而双层六直叶涡轮桨混合时间的模拟值要比实验结果长约一倍。此外，本文还采用数值模拟的方法研究了不同的示踪剂加料点、监测点位置及操作条件对混合时间的影响规律，模拟结果表明，混合过程主要由搅拌槽内的流体流动所控制，混合时间与示踪剂加料点及监测点位置密切相关。 <WP=5>本文的研究结果对工业搅拌反应器的优化具有一定的参考意义。更多还原

【Abstract】 Mechanically agitated reactors are widely used in many industrial processes. Mixing time is one of the key parameters to the design of stirred reactors. Only a few studies were carried out on the numerical simulation of mixing process by using computational fluid dynamics (CFD). The mixing time in the stirred tank of 0.476m diameter with single and dual impellers was studied respectively by using CFD package FLUENT6.0. Rushton turbine and three narrow blade hydrofoil CBY impeller were used in the simulation. The multi-reference frame (MRF) and standard k－ε turbulent model were used in the simulation. For the single impeller agitator, the mixing time predicted by CFD is in a good agreement with the experiment. For the dual impeller agitator, the mixing time of dual CBY impeller predicted by CFD is in a good agreement with the experiment, the mixing time of dual Rushton turbine predicted by CFD is about two times that of experiment. The effects of tracer feeding and detecting positions on mixing time were also investigated. The simulation results indicate that the mixing <WP=7>process is dominated by the flow field in the stirred tank. Feeding and detecting positions have important effect on mixing time. Feeding of tracer at the impeller region has a much shorter mixing time than at the liquid surface. The results are of importance to the optimum of industry stirred reactors.更多还原