基于高通量膜分散技术的气液混合过程调控及模拟

Control and Simulation of Gas-liquid Mixing Process based on High-throughput Membrane Dispersion Technology

利用数字图像处理和高速显微镜成像系统相结合的方法获取气泡的大小、形状、流场信息,考察了多通道陶瓷膜混合器内不同操作条件和液相性质对气泡尺寸和气含率的影响规律。结果表明,气泡尺寸随气液通量和气液比增大而增大,一定范围内较低的液相表面张力和黏度更易于形成微小气泡,实验体系下制备气泡平均直径为300μm~3 mm。气含率主要受到气泡尺寸和气体流量的影响,气泡越小、气体流量越大,气含率越高。采用计算流体力学方法(CFD)进一步剖析膜分散法形成气泡的机理,研究操作条件和膜结构影响气液混合效果的机制。模拟结果阐明了陶瓷膜管不同通道对气液分散的贡献分配,跨膜压差和气含率的计算值与实验值偏差分别为±10%和±15%,模型准确度较高。结合实际生产需求对膜结构进行优化设计,分析了19通道型、花瓣型和中空型3种陶瓷膜管构型的内部流场变化和气泡特性,对比了三者在气含率、渗透通量等方面的利弊,为优化工艺参数和混合器结构、实现微气泡体系尺度及分布的精准调控提供了理论支持。

The size,shape and flow field of bubbles were obtained by digital image processing and high speed microscope imaging system.The effects of dif ferent operating conditions and liquid phase properties on bubble size and gas holdup in a multi-channel ceramic membrane mixer were investigated.The results showed that the bubble size increased with the increase of the gas-liquid flux and gas-liquid ratio,and the surface tension and viscosity of the liquid phase were lower in a certain range,and the average diameter of the bubbles prepared under the experimental system was 300μm~3 mm.The gas holdup was mainly affected by the bubble size and gas flow rate.The smaller the bubble and the larger the gas flow rate,the higher the gas holdup.The computational fluid dynamics(CFD)method was used to further analyze the mechanism of bubble formation by membrane dispersion method,and the mechanism of operating conditions and membrane structure affecting the gas-liquid mixing effect was studied.The simulation results illustrated the contribution distribution of different channels to the gas-liquid dispersion of the ceramic membrane tube.The deviations between the calculated values of the transmembrane pressure difference and the experimental values were±10%and±15%,respectively,indicating high accuracy of the model.According to the actual production requirements,the membrane structure was optimized and designed,and the internal flow field changes and bubble characteristics of the three ceramic membrane tube configurations,19-channel,petal and hollow,were analyzed.The advantages and disadvantages of the three configurations in terms of gas holdup and permeation flux were compared,which provided theoretical support for optimizing the process parameters and the structure of the mixer,and realizing the precise control of the size and distribution of the microbubble system.