离子液体体系碳捕集过程两相流流动与传质规律研究

Although CO2 capture from flue gas with ionic liquids has been regarded as an effective and promising method, the mass transfer and two phase flow properties of CO2 absorption in these solvents have not been researched.The two phase flow dynamic and mass transfer character in the process of CO2 capture by room temperature ionic liquids (such as BmimBF4) and task specific ionic liquids blend with amine will be studied in this work. First, a cylindrical bubble column and a packed column were built for two phase flow dynamic and mass transfer test, and distribution of bubble size、 bubble rising velocity 、gas hold-up、liquid hold-up and effective interfacial area were determined using various situ analysis technologies. A reaction kettle and a wetted wall column will be modified to test mass transfer coefficient,including overall volumic mass transfer coefficient、liquid-side mass transfer coefficient and gas-liquid interficial flux. Second, the bubble performance and motion law in reactor will be simulated using the Euler-Euler method and population balance model(PBM) coupled numerical model,and a new drag force coefficient is added to the momentum equation to show a new model.Considering the ionization equilibrium of ionic liquids association and electrostatic and reaction dynamic, the gas-liquid two phase mass transfer model will be proposed to describe the ionic liquids CO2 capture processes. Finally, above all results will be used to solve the problem that the traditional model is not appropriate for ionic liquids, and to select and improve ionic liquids CO2 capture reactor.

离子液体体系捕集CO2具有许多优于醇胺法的特点，已显示出良好的工业应用前景，但捕集CO2过程的两相流动和传质等化工基础研究不足。本项目以物理吸收离子液体以及化学吸收功能化离子液体/有机胺复配体系为吸收介质，首先在夹套式鼓泡反应器、填料吸收塔、反应釜和湿壁塔等实验装置上，采用多种原位分析技术，获得气泡行为、气含率、持液量和有效传质面积等的动态规律，以及体积传质系数、表界面传质通量和循环吸收性能等过程传质规律，揭示功能化离子液体在复配吸收剂碳捕集过程中的节能调控规律。其次将实验结果与数值模拟相结合，采用双流体模型与群平衡模型相耦合，引入新的曳力系数表达式，模拟反应器内的气泡行为和两相运动规律；将表达离子液体介质的静电和缔合作用的电离平衡和反应动力学嵌入已有模型中，提出适用于离子液体体系吸收CO2过程的气液传质模型。最终解决现有模型在预测离子液体体系碳捕集过程中流动和传质准确度和适用范围问题。

离子液体具有许多优于醇胺法的特点，将离子液体与醇胺复配能够克服离子液体高粘度等诸多缺点，研究离子液体在复配体系中的作用机理，明确流动传质规律是该体系吸收剂工业化应用的关键。本项目按照项目计划，以离子液体/有机胺复配体系为吸收介质，研究了吸收剂的循环吸收性能，气液两相传质、流动及反应动力学特性。采用模拟与实验相结合，揭示了离子液体在复配吸收剂碳捕集过程中的节能调控规律，通过离子液体阴阳离子的调节可以有效降低复配吸收剂碳捕集过程中的反应热，同时提高碳捕集循环吸收量。提出了适用于复配离子液体体系的气液相平衡预测模型。将离子片热力学与计算流体动力学相结合，引入了适用于复配离子液体体系的曳力模型，提出了针对复配离子液体体系的耦合新方法，建立了适用于复配离子液体体系的欧拉-拉格朗日方法。这些研究成果为复配离子液体体系的碳捕集工业化应用奠定了良好的基础。