不互溶液液体系相间动态混合传质过程的实验与数学模型研究

The immiscible liquid-liquid dispersion involves many simultaneous, interdependent phenomenon. The characteristic rates of different processes are difficult to be coordinated under the scale-up effect, which leads to the imperfect manipulation of industrial devices. Therefore, the interaction mechanism of the hydrodynamics and mixing along with mass transfer in liquid-liquid reactors is urgent to know, and efficient methods are needed to accomplish the practical purposes. In order to solve this problem, experiment, mathematical modeling and numerical simulation are employed in this project. First, the dynamic interphase mass transfer in immiscible liquid-liquid systems will be visualized with the planar laser induced fluorescence method (PLIF). The influence of operation conditions such as the phase holdup on the scale-dependent coupled process will be quantitatively revealed by the overall mixing time. Finally, the explicit algebraic mass flux model (EAMFM) and the two-dimensional population balance model (2V-PBE) will be developed to consider the anisotropic turbulent mass diffusivities and the properties of dispersed droplets characterized by size and composition. Combining with the high-accuracy and low computational cost two-phase explicit algebraic stress model (EASM) and the interphase mass transfer model, a comprehensive multi-process coupling model and numerical method will be established to predict the dynamic homogenization process of solute in two phase systems under different conditions. The reactor-scale manipulation rules can be formulated, which lays the foundation for the design and scale-up of industrial reactors.

不互溶液液体系分散具有多过程紧密动态耦合的特点，反应器放大时各过程速率难以协调匹配，导致工业装置无法有效调控。因此，急需从机理上清晰、定量地认识反应器内液液两相体系流动、混合、相间传质耦合行为规律，并开发相应的调控方法和技术。本项目从实验、多相流数学模型和模拟方法出发，采用平面激光诱导荧光技术对不互溶液液体系相间动态传质进行可视化测量，通过总体宏观混合时间定量揭示相含率等操作条件对多相流动、混合以及传质动态耦合过程的影响机制和规律；在实验基础上，考虑湍流传质的各向异性以及分散相尺寸和溶质分布的非均性，建立显式代数质流模型以及二维群体平衡模型，并将其与高精度、低负荷各向异性两相显式代数应力模型以及相间传质模型结合，形成多过程耦合模型和模拟方法，预测不同条件下溶质在不互溶液液两相体系中的动态均一化过程，归纳反应器尺度上过程强化的调控规律，为工业液液反应和分离设备设计和放大提供理论基础。

不互溶液液体系的分散是一个重要的单元操作，其具有多过程紧密动态耦合的特点。为了实现不互溶液液反应器放大及有效调控，需要针对搅拌槽内不互溶液液两相体系流动、混合、相间传质多过程耦合行为规律进行深入研究。本项目（1）首先将平面激光诱导荧光法与折射率匹配技术创新性地应用于搅拌槽NaI-辛醇不互溶液液两相体系相间动态传质的可视化测量，建立了一种不互溶液液体系相间传质平衡时间的测量装置及其测量方法，考察了搅拌反应器内分散相体积分数、搅拌转速、桨型、桨叶离底高度和偏心搅拌等操作条件对相间传质平衡时间的影响，获得了流动、混合和传质动态耦合过程的规律性认识；（2）其次，基于实验确定的荧光强度和浓度间的线性关系，将可视化实时记录的图像通过灰度值分析处理后转化为对应的浓度值，进而计算有机相侧传质系数，考察了搅拌转速和示踪剂浓度等对恒界面池内相间传质系数的影响规律，并拟合了NaI-辛醇液液体系相间传质过程的传质经验关联式；（3）最后，采用多相流体力学理论、传质理论和数值计算方法等，建立了考虑组分脉动浓度湍流输运的搅拌槽宏观混合模拟模型，即显式求解组分输运方程中的脉动速度与脉动浓度的关联项，从而反映湍流传质过程的各向异性特征。利用此模型模拟搅拌槽内宏观混合过程，并与电导率法获得的宏观混合时间以及监测点无量纲示踪剂浓度响应曲线进行了对比验证。这些成果加深了对搅拌槽不互溶液液体系流动、混合及传质动态耦合过程的认识，可为工业液液反应器的设计和优化提供理论基础。