流化床聚合反应器两相流动和颗粒尺度演变研究

Critical scientific problems in fluidized bed polymerization reactors, such as, tracking of the meso-structure of particle cloud, interaction rule among two phase dynamics, particle size distribution and micro-behaviors, dependence of particle size distribution on operation and equipment geometry characteristics, have not been clarified. In order to resolve these problems, cluster Lagrangian algorithm, solution method of population balance equation and their coupling relation are investigated in depth, and an Euler-"cluster Lagrange"- "local fixed pivot quadrature method of moment" coupled model is developed, which is good at tracking meso-structure of particle cloud and makes accurate predictions of particle size distribution and its moments. Two phase dynamics, particle size distribution and micro-behaviors can be collaboratively predicted and the law of their mutual influence can be also acquired easily. Moreover, it is also beneficial to clarify the dependence of particle size distribution on operation and equipment geometry characteristics and develops a new idea on numerical simulation of polydisperse two-phase fluid dynamics and prediction of particle size distribution. It will provide theoretical foundation for design, optimization and investigation of reactors and improvement of operation. Thus, the present project deserves important academic value and has significant application prospects.

流化床聚合反应器内颗粒群介尺度结构的准确捕捉，两相流动、颗粒尺度分布及颗粒相微观行为三者的相互影响规律，颗粒尺度分布对操作条件和设备几何特征量的依赖关系等关键科学问题尚未阐明。针对这些问题，本项目通过对颗粒团拉格朗日算法、群体平衡模型的求解算法以及模型耦合流程进行深入研究，拟开发"欧拉-颗粒团拉格朗日算法-群体平衡模型的局部定点矩积分方法"一体化耦合预测模型。该模型将兼顾拉格朗日算法在颗粒流动介尺度行为捕捉上的优越性和局部定点矩积分方法在矩和分布高精度跟踪的优点，可实现反应器内两相流体动力学、颗粒尺度分布和颗粒相微观行为的协同预测以及三者相互影响规律的获取，有助于阐明颗粒尺度分布对操作条件和设备几何特征参数的依赖关系，为多分散系统两相动力学模拟和颗粒尺度分布预测开拓新思路。该模型为流化床聚合反应器的设计、优化、研制以及现有操作条件的改善提供理论依据。因此，具有重要的学术价值和重大应用前景。

流化床聚合反应器是典型的多相多分散颗粒系统，系统中两相流体流动、颗粒尺度分布以及颗粒相微观行为三者相互影响且耦合在一起，探究它们之间的相互影响关系，对流化床聚合反应器的优化设计具有重要意义。本项目围绕聚合反应器内流体动力学行为、颗粒尺度演变以及颗粒相微观行为展开，发展了颗粒团离散单元法，适用于多相网格质点法的能量耗散模型，多分散系统的两层网格算法，适应于大规模计算的曳力系数插值方法，实现颗粒分布和分布矩双跟踪的局部定点矩积分方法，多分散系统的两层网格算法，最终在欧拉架构下跟踪流体的运动，在拉格朗日架构下跟踪颗粒的运动，并通过两相数据映射实现了两者的耦合，开发出了适合于多相多分散系统的中两相流动、颗粒尺度分布以及颗粒相微观行为的一体化预测模型，为多分散系统的研究开拓了新思路，该模型为流化床聚合反应器的设计、优化、研制以及现有操作条件的改善提供理论依据。因此，具有重要的学术价值和重大应用前景。