多相流动反应耦合系统的动力学特征分析及

王维

摘 要：针对“多区协控”思想下的催化裂化工艺特点，该研究力图深入认识多相流动反应体系中介尺度结构的形成和影响机制，建立基于结构的描述方法和在流动反应耦合条件下的多尺度模型；在此基础上，模拟催化裂化的关键过程和区域，为“多区协控”新工艺开发提供优化设计方案和指导。经过两年的研究，取得以下成果：基于上述思路，该研究提出了结构多流体模型，并用以解释介尺度结构与守恒关系间的影响，统一了经典的双流体模型以及EMMS模型，为亚网格层次的EMMS曳力与双流体模型耦合奠定了理论基础；该理论形成的EMMS亚网格曳力，经过简化的力平衡关系，已用于分析非均匀广义流化系统中的各种流动稳定性问题，完成了主要工业操作单元（包括预提升段、主提升段、再生器、旋风分离器等）涉及的广义流化分析和多区相图，分析影响各区流动的稳定性条件；该理论与CFD模拟结合，已应用于模拟提升管入口段的流动混合情况，捕捉到了理论预测的二次流现象；完成了提升管进料段气固两相流动及催化裂化汽提段内气固流动特性的模拟初步研究；初步分析了不同进料角度对两相流动，特别是二次流的影响，模拟结果与实验符合较好；为优化入口设计提供了依据；该理论还用于提升段的反应过程分析，模拟结果与现有的工业数据较为吻合，取得了较好的效果。总之，在FCC多区协控强化的理论基础上，这一研究工作，深化了两相流模拟与分析的方法基础，并在应用中解决了实际问题。

关键词：流态化 计算流体力学 模拟 多尺度 流化催化裂化

Abstract：In line with the idea of “coordination between multiple zones” for fluid catalytic cracking （FCC）， this research is to investigate the mechanism of meso-scale structure and its effects on the multiphase reactive flow systems and thereby establish a set of structure-dependent methods for multiscale modeling of reactive flow systesm. The proposed model thereon will be applied to simulate key processes and areas in FCC reactor and then help optimal design of novel processes. Several achievements have been obtained as follows： The structure-dependent multi-fluid model （SFM） was proposed to describe the interrelationship between meso-scale structure and conservation laws. The SFM was found to unify the classic two-fluid model （TFM） and the energy minimization multiscale （EMMS） model with different structures. That paves the solid base for why we can use the EMMS drag model at sub-grid level for the homogeneous TFM because the TFM is actually the filtered or averaged description of the SFM at each grid. The sub-grid EMMS drag was used in a simplified force balance equation to analyze different kinds of aggregative fluidized systems and the stability issues therein. A generalized fluidization diagram with consideration of meso-scale structure was drawn for the reactor units involved such as riser， regenerator and separator and so on. The SFM was integrated into CFD for simulation of the mixing phenomena in inlet area of a riser. The secondary flow phenomenon was captured successfully that coincides with theoretical analysis. Simulation of stripper area was also performed. The effects of inlet angle and configuration on the two phase flow， in particular， the secondary flow， were studied extensively. These work provide basis for optimization of inlet configuration of riser. The multiscale model has been also applied in reactive flow simulation of FCC reactor. The results show good agreement with industrial data available. In summary， on the basis of the theory of “coordination between multiple zones” for FCC， this work paves physical basis of relevant two-phase flow study and it has been validated by solving industrial problems.

Key Words：Fluidization；CFD；Simulation；Multiscale；FCC

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