Lightnin型交错流静态混合器内介尺度流动特性与离散相液滴快速分散混合机理

Static mixer has been proposed as a novel liquid-liquid rapid mixing equipment. It have displayed fantastic performance of mass transfer and mixing intensification in the industrialized production of nitrobenzene by new variable temperature nitration technology of high water and low nitrification nitrate static mixing tube. In order to reveal the meso-scale characteristics of liquid-liquid two phase flow, both dispersive mixing characteristics of dispersed phase droplets and enhancement mechanism of the two-phase interfacial rapid mass transfer will be investigated in the Lightnin staggered static mixer. Transient evolution of droplet groups will be analyzed firstly in the characteristic regions of the mixer by the TR-PIV. A mathematical model will be established based on computational fluid dynamics and population balance model. And the effect of liquid-liquid velocity, fluid property, the structure and size of Lightnin mixing segments on the process of rupture, collision, coalescence and deformation of droplet will be studied. Secondly, the flow pattern map and the online prediction model will be established based on the PLIF experiment combined with the spatial and temporal inhomogeneous distribution characteristics of droplets. The effect of the multiphase meso-scale scale flow characteristics on the transfer-flow behavior and the coupling mechanism then will be analyzed. At last, interfacial concentration and temperature distributions of nitrification phase in the staggered flow can be investigated based on the Stokes and convection diffusion equation. The strengthening mixing effect on the concentration distribution will be quantitative analyzed in the staggered static mixing reactor compared with the traditional tank nitrifying reactor, which will provide theoretical support for further promoting the industrialization in more widely applications.

静态混合器作为新型液液两相流快速混合设备，在高水低硝酸静态混合管式变温硝化新工艺制取硝基苯等工业化生产中彰显出卓越的强化传质性能。为了揭示交错流道内液液两相介尺度流动特性、离散相液滴的分散混合特性和两相界面传质增强机理，首先，利用TR-PIV对交错流静态混合器内不同特征区域内液滴群瞬态演变行为进行实验测量，将计算流体动力学与群体平衡模型相结合构建数值模型，研究液液流速、液体物性、交错流道结构和尺寸等对介尺度下液滴的分散、碰撞、变形过程的影响规律；其次，基于PLIF实验结合液滴在尺寸、空间的不均匀分布和随时间的多变性为特征建立液液两相流型图和预测模型，分析多相介尺度流动特性对传递-流动行为的影响及其耦合规律；最后，以斯托克斯和对流-扩散方程为基础，开展交错流相界面浓度和温度分布特性研究，定量分析交错流较传统釜式硝化反应器改善混合器内的浓度分布和强化混合效果状况，为其工业化进一步推广提供理论支持。

静态混合器作为新型液液两相流快速混合设备，在高水低硝酸静态混合管式变温硝化新工艺制取硝基苯等工业化生产中彰显出卓越的强化传质性能。为了揭示交错流道内液液两相介尺度流动特性、离散相分散混合特性和两相界面传质增强机理：. 首先，利用高速相机对交错流静态混合器内不同特征区域内多相流瞬态演变行为进行实验测量，与计算流体动力学模型相结合构建数值模型，分析流速、物性、交错流道结构和尺寸等对介尺度下离散相的快速分散混合特征的影响，发现LSM内能耗G值高于KSM并且其随混合元件长径比的减少而逐渐增加，G值与Re在对数坐标系统下满足线性关联，LSM内延伸率分布规律揭示其流动主要以简单剪切流为主，Ar=1、1.5和2的LSM分别比Ar=1.5的KSM的拉伸率高39.14%-59.97%，26.23%-44.18%，26.60%-30.03%。. 结合多相流动的非稳态特性和空间运动的随机性为特征建立混沌混合强化模型，提出静态混合器内无质量粒子分布和分散混合均布表征模型，优化无质量粒子分散混合程度量化的结构化半径计算方法，提出混沌混合强化综合性能因子评价分散和分布混合性能，Lightnin静态混合器的混合强化能力高于Kenics静态混合器，特别Ar=1时达到30%-78%。. 最后，以计算流体动力学和传热学为基础，研究交错流混合元件诱导静态混合器内外螺旋区域传热和流动特性，考虑到静态混合元件截面形状的影响，完善何雅玲教授小组（Int. J. Heat Mass Tran., 52: 33−44）提出的无量纲传热系数与流阻系数关联式，建立适合静态混合器综合传热性能评价图；研究交错流螺旋元件结构诱导射流强化管壁与扭带之间耦合强化特性优化双泪滴型中心孔结构（d/w=0.3和s/w=0.6），揭示传热系数传热性能Nu准数随雷诺数增加呈现反对称关系；利用5种不同的评价方式对协同角进行计算，通过分析选择模点积平均角作为协同角的评价标准；明晰研究孔径、间距和交错角等因素对混合器内流动－混合－传热协同机制影响及强化机理。