膜微反应器中流动与传质性能研究及其应用

发布时间：2018-05-11 08:29

本文选题：膜微反应器 + 微通道　；参考：《北京化工大学》2015年博士论文

【摘要】：化工过程强化技术是在不改变已定生产任务的同时,通过缩小设备体积,简化生产工艺,压缩设备数量,使整体产线布局更加紧凑合理,显著降低能耗、废料和副产品产出。发展新型反应分离耦合技术与装置对化工反应过程强化具有重要的理论意义和应用价值。微化工系统的出现为绿色、安全、高效的完成反应过程提供了新的技术和方法,而膜反应技术通过反应与分离耦合实现了生产过程的有效强化。论文将微流控技术与膜分离技术结合,设计发展新型膜微反应器,从而实现反应-分离耦合过程的强化。但是,作为一个新的研究方向,目前关于膜微反应器的理论研究非常少,要实现反应与分离耦合过程的强化,需要对膜微反应器内流体流动、传质及膜壁面传质性能有深入的研究。本论文首先以矩形微通道为液相流动规律研究平台,探讨了微尺度下流动基本规律。通过可视化实验与计算流体力学模拟,分析了流体与通道壁面浸润性能对液相流动的影响。通过分析不同流型时微通道内挤压力、剪切力和界面张力的作用关系,指出了用连续相流速表示剪切力大小,使用两相流量作为划分流型的主要依据,实现了多种流型(层流、液柱分散流、液滴分散流等)问的可控转换。对不同流型时的速度场进行了分析,指出不同流场下主导作用力的区别。为膜微反应器中流体流动规律的研究提供了理论基础。其次,利用渗透汽化膜微反应器考察了不同操作条件下膜分离性能。系统研究了不同料液温度、水含量和流速时,膜微反应器对正丁醇／水体系的分离性能。根据溶解-扩散机理,采用串联阻力模型,建立了渗透汽化传质半经验模型。为膜微反应器应用于反应-分离耦合过程提供了理论依据。再者,基于微通道中流体流动基础理论,建立了膜微反应器中流动方程,并利用有限傅立叶变换求解此方程,通过渗透汽化脱水过程,评价模型的使用。在流动模型的基础上,建立了膜微反应器中二组元对流扩散模型,通过模拟计算得到出口截面水浓度,并与实验结果相比较。丰富了微尺度下流体流动的基本理论。最后,在膜微反应器内流动与传质性能研究的基础上,以酯化反应为例,分析了催化膜微反应器对渗透汽化-反应耦合过程的强化作用。在相同的反应条件下,膜微反应器内反应转化率较常规尺寸膜反应器中有很大提高,并且在膜微反应器中可有效减缓催化剂失活。
[Abstract]:Chemical process strengthening technology is to reduce the volume of equipment, simplify the production process, compress the number of equipment, make the overall production line layout more compact and reasonable, significantly reduce energy consumption, waste and by-product output. The development of new reaction separation coupling technology and equipment has important theoretical significance and application value for chemical reaction process strengthening. The emergence of micro-chemical systems provides a new technique and method for green, safe and efficient completion of the reaction process, while the membrane reaction technology can effectively strengthen the production process through the coupling of reaction and separation. In this paper, a new membrane microreactor is designed and developed by combining microfluidic technology with membrane separation technology, so that the coupling process between reaction and separation can be strengthened. However, as a new research direction, there is very little theoretical research on membrane microreactor. In order to enhance the coupling process of reaction and separation, fluid flow in membrane microreactor is needed. Mass transfer and film wall mass transfer properties have been studied in depth. In this paper, rectangular microchannels are first used as the platform for the study of liquid flow law, and the basic law of flow at microscale is discussed. The effects of fluid and channel wall wettability on liquid phase flow were analyzed by visual experiment and computational fluid dynamics simulation. By analyzing the relationship between extrusion force, shear force and interfacial tension in microchannel with different flow patterns, it is pointed out that the shear force is represented by the velocity of continuous phase and the flow rate of two phases is used as the main basis for classifying flow patterns, and various flow patterns (laminar flow) are realized. Column dispersion, droplet dispersion, etc. The velocity field of different flow patterns is analyzed and the difference of dominant forces under different flow patterns is pointed out. It provides a theoretical basis for the study of fluid flow in membrane microreactor. Secondly, membrane separation performance under different operating conditions was investigated by pervaporation membrane microreactor. The separation performance of n-butanol / water system by membrane microreactor with different feed temperature, water content and flow rate was studied systematically. According to the mechanism of solution-diffusion, a semi-empirical model of osmotic vaporization mass transfer was established by using the series resistance model. It provides a theoretical basis for the application of membrane microreactor in the reaction-separation coupling process. Furthermore, based on the basic theory of fluid flow in microchannels, the flow equation in membrane microreactor is established, and the finite Fourier transform is used to solve the equation. The application of the model is evaluated through the process of pervaporation and dehydration. Based on the flow model, a two-component convection-diffusion model in a membrane microreactor was established. The water concentration at the outlet section was calculated by simulation, and the results were compared with the experimental results. It enriches the basic theory of fluid flow in microscale. Finally, based on the study of flow and mass transfer in membrane microreactor, the enhancement effect of catalytic membrane microreactor on the coupling process of pervaporation and reaction was analyzed by taking esterification as an example. Under the same reaction conditions, the conversion rate in the membrane microreactor is much higher than that in the conventional membrane reactor, and the deactivation of the catalyst can be effectively slowed down in the membrane microreactor.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ052

【相似文献】