超细气泡反应体系的传质特性与介尺度构效调控

Due to the drawbacks of the traditional gas-liquid reactors, including high bubble size, limited mass transfer area, low gas utility and the like, by combining the hydraulic dynamics and mechanical bubble crushing, new ultrafine bubble reactor (UBR) is constructed with liquid-gas ejector and bubble breaker. UBR can make the interface for liquid gas mass transfer from the traditional millimeter-centimeter size to the micron, and thus dramatically increases the interfacial area, intensifies biphase reaction and achieves scale structure-efficiency regulation. By using Rapid Freezing-MicroCT and particle image velocimetry(PIV), the bubble size distribution can be identified, and the relationships of micro bubbles behavior with the reactor configuration and operation parameters can also be evaluated to build mathematic model for the regulation of bubbles. According to the research on mass transfer and reaction in UBR, the UBR mass transfer intensification model and kinetic model for toluene oxidation in UBR will be built. Then, a mathematic relationship between bubble superficial area, intensification factor of mass transfer and energy consumption is to be constructed. According to Nonequilibrium Thermodynamic Model, the entropy contribution of every part and zone will be evaluated to identify the energy consuming behavior and help the optimization, thus, the structure optimization and regulation of UBR can be performed accordingly to lead the development of gas-liquid reactor from bubble reactor (millimeter-centimeter size) to UBR with micron.

本课题基于鼓泡塔等传统气液反应器内气泡大、传质面积小、气体利用率低的问题，结合水力动力学和机械破碎原理，将液气射流与气泡破碎器有机结合，构建超细气泡反应器UBR（Ultrafine bubble reactor），将气液传质界面尺度从传统的毫-厘米级减小至微米级，大幅增强气液传质，强化反应，实现介尺度构效调控。综合运用激冷-MicroCT法和粒子图像速度仪等技术，测定超细气泡形态，确定设备结构-气泡形态-相界面关联，建立气泡形态控制模型，同时结合UBR内的传质与反应研究，建立UBR强化传质模型和基于超细气泡反应器的甲苯氧化动力学模型。最后采用非平衡热力学熵增速率原理，建立气泡表面积、传质系数强化因子与系统能耗之间的数学关系，评价超细气泡发生器各结构、各区域的熵增贡献，确定体系能耗分布，以指导UBR的结构优化和调控设计，并引导气液反应体系的研究从目前的毫-厘米尺度鼓泡反应器向UBR层次发展。

建立了超细气泡形态控制模型，明确了超细气泡尺寸与流体物性、温度压力等操作条件与反应器结构等因素的关联关系。结合喷射反应器下降管内的能量耗散速率的计算，构建喷射反应器气含率、气液相界面积的计算模型，形成了超细气泡喷射反应器内气泡形态—气液流动行为—气含率—相界面积关联关系。对于CO2-NaOH吸收体系，相同操作参数下，FBJR内反应时间比鼓泡反应器缩短近一倍，液相体积传质系数大约为鼓泡反应器的10倍。通过气泡运动和传质的耦合，明确了气泡初始直径对气泡上升过程中传质的影响，确定有效传质高度，从而形成气泡尺寸与反应器结构尺寸的关联，获得反应器内整个液层内的气含率、气液相界面和传质速率，进而形成了气泡尺寸—能耗和传质之间的数学关系。项目以甲基芳香烃氧化为模板，开展了甲苯高选择性氧化体系的研究和应用，分别构建了高醛选择性体系和高反应速率体系，开发了非酸性溶剂、非金属催化的高效氧化体系，并设计了连续化放大反应器，以利用超细气泡传质调控理论，以检验超细气泡反应体系的工业应用效能。