持液气固流化床中粘性颗粒流化的跨尺度关联及流型转变研究

持液粘性颗粒流化体系在烯烃聚合、催化裂化、干燥造粒等化工过程中应用广泛，但液体加入易诱发聚团结块和流化失稳等故障，因此亟需研究微观参数及作用与宏观行为特性间跨尺度机制及其中的介尺度结构及效应。项目采用AFM等精密仪器结合FFT分析表征手段，获取颗粒表面粗糙度/表界面物性等微观参数，考察上述参数对颗粒间液桥作用力的影响规律，建立考虑微观参数影响在内的液桥作用力修正模型，为CFD-DEM耦合模拟中液桥力和接触力模块提供重要的输入参量及模型，开展液桥和流场耦合作用下的持液颗粒流化模拟研究，并采用系统尺寸无关性参数进行验证。基于测量及模拟结果，通过无量纲参数及量化分析获取多层次表征手段，重点关注介尺度聚团及其效应的表征分析，以实现微观液体作用机制和宏观流化特性间的跨尺度关联，进而揭示液桥静态/动态双重效应的作用规律和转变机制，建立持液颗粒流化过程的流型转变判据，为强化粘性颗粒的稳定流化提供新思路。

Liquid-containing gas-solid fluidized bed has been widely applied in various chemical engineering processes, such as FCC, olefin polymerization, drying, granulation and so on. However, liquid addition causes some unstable phenomena such as meso-scale agglomeration and defluidization. Thus, it is so urgent to study meso-scale stucture effects and trans-scale correlation between micro-scale interaction and macro-scale behavior in this field. In this project, the precise AFM/SEM measurement techniques will be used to obtain particle surface roughness and other micro-scale interfacial parameters. By considering the effects of surface roughness and other micro-scale parameters on liquid bridge forces among particles, the modified liquid bridge interaction force model will be proposed. Based on these results, some key input parameters in the liquid bridge force module and contact force module can be provided for CFD-DEM coupling numerical simulation. Therefore, the liquid-containing cohesive particle fluidization with liquid bridge and flow coupling actions will be studied by using the proposed CFD-DEM model, meanwhile the system-size independent validation scheme is also applied in this work. Based on the experimental measurements and simulation results, the link between micro-scale liquid interaction mechanism and macro-scale fluidization behavior/characteristics can be established via multi-level dimensionless parameter analysis. With the help of meso-scale agglomeration analysis, the trans-scale correlation in the liquid-containing cohesive fluidization can be established. All these studies can be used to reveal liquid bridge static/dynamic effects and their transition mechanism, and then to establish regime transition criterion and corresponding regulation means. In summary, this project provides a new research route for trans-scale correlation and multi-scale analysis in the liquid-containing cohesive particles fluidization and will further promote development and advance of the related fluidization engineering technology.