基于Fluent的大型苏氨酸发酵罐内搅拌流场仿真分析

Simulation analysis of agitating flow field in largethreonine fermentor based on Fluent

以大型苏氨酸发酵罐内流场为研究对象,利用Fluent软件,采用了多重坐标参考系法(MRF)以及欧拉(Eulerain)模型,结合苏氨酸发酵过程中工艺参数,对发酵罐内四档搅拌桨组合的搅拌过程进行单相流、气液两相流数值模拟,研究分析了发酵罐内流场情况、搅拌桨功率大小以及含气率等参数。结果表明,液面升高对已浸没的搅拌桨功率影响不大;发酵过程中密度增大会导致搅拌桨功率增加,二者呈近似正比例关系;通气后搅拌桨总功率下降了20.9%,溶液平均含气率稳定在21.4%左右。

The flow field in large threonine fermentor as the research object,by using Fluent software,combining the parameters of threonine fermentation process,and the method of computational fluid dynamics with Multiple Reference Frame and Eulerian multiphase flow model was used to the simulation of singlephase flow and gas-liquid two-phase flow in the mixing process of four stage impeller assembly in fermentor.Distribution of fluid field、power of impeller and volume fraction of gas-phase were also analyzed.The results show that the power of submerged impeller was not affected by the increase of liquid level,and the increase of density in the fermentation process would lead to an increase in the power of the impeller and the two factors are approximately proportional.Moreover the total power of the pro-peller decreased by 20.9% after aeration,the average volume fraction of gas was stable at about 21.4%.