移动床气固反应器多相耦合热质传递机制研究

The moving bed reactor is a key technological facility which is widely used in chemical engineering, power generation and metallurgy industry. Inside the moving bed reactor, the complicated multiphase flow is coupling with the heat and mass transfer. In this work, the mechanism of the multiphase flow coupling with transport processes will be investigated. The discrete element method (DEM) soft sphere model, which is based on the granular contact mechanics theory and adopts nonlinear elastic contact constitutive equation, will be developed for granular flow in the moving bed. With the computational fluid dynamics (CFD) method, a DEM-CFD coupling model will be developed for dense multiphase flow and transport processes inside the moving bed reactor. In this coupling model, the interaction between gas and solid is depicted by the improved drag model and the cell particle source term method is adopted to deal with the gas-solid two-way coupling. The gas-solid chemical reactions inside moving bed reactor are also taken into account in the model. The governing equations solution algorithm is improved for high computational efficiency. The experiments under cold and thermal condition are performed to validate and improve the DEM-CFD model. The complex process inside the typical moving bed gas-solid reactor will be simulated to investigate the mechanism of multiphase flow coupling with heat and mass transfer and the effects of primary technological operation parameters on the reactor performance. This work is significant for developing the advanced numerical methods, which is used to simulate the complicated multiphase flow coupling with heat and mass transfer, as well as improving cognitive level of mechanism of complex technological process inside the moving bed gas-solid reactor.

移动床气固反应器是化工、能源以及冶金等工业领域广泛应用的反应装置，内部存在复杂的多相流动耦合热质传递过程。本项目旨在探索其多相耦合传递机理，拟采用非线性弹性接触本构，构建基于颗粒接触力学理论的离散单元法（DEM）软球模型，并与计算流体力学分析方法相结合，改进曳力模型用于描述气固相间作用，采用单元中颗粒源项法处理气固相间双向耦合，考虑移动床内化学反应的影响,构建描述移动床气固反应器浓相气固多相流及其传热传质过程的DEM-CFD耦合数学模型，发展相应算法以提高计算效率，并结合冷态和热态实验验证和完善模型。利用模型研究典型移动床气固反应器内气固相运动规律、耦合传递机制、传热传质特性以及工艺操作参数的影响规律。本项目的研究对于发展复杂多相流耦合热质传递过程模拟的先进数值方法，提高对移动床气固反应器复杂工艺过程机理的认识水平，具有重要的学术意义和应用价值。

移动床气固反应器是化工、能源以及冶金等工业领域广泛应用的反应装置，内部存在复杂的多相流动耦合热质传递过程。本项目通过构建数理模型并结合冷态和热态试验，在移动床气固反应器中多相流动规律和传热传质特性研究方面取得若干进展，主要包括：(1) 针对COREX熔融气化炉移动床的炉料运动过程，基于软球模型及离散单元法（DEM）进行数值模拟并结合冷态实验研究，获得了颗粒流的时间线、速度分布及死料柱的几何特征，揭示了熔融气化炉移动床内炉料颗粒的运动规律；(2) 通过热重实验研究证实了烧结矿作为化学链反应载氧体的可行性及其循环性能，获得了描述载氧体颗粒氧化还原过程的未反应收缩核模型（USCM）的无量纲积分表达式，通过移动床反应器热态试验和数值模拟，研究了反应温度、颗粒粒径以及气固比对反应特性的影响规律，为化学链移动床反应器的设计提供依据；(3) 基于分布式活化能模型（DAEM）和传热模型建立了大颗粒煤热解过程传热传质耦合数学模型，研究了大颗粒煤热解过程挥发分各组分的析出规律以及煤颗粒尺寸、升温速率对热解过程的影响，结合煤热解动力学模型和气固换热模型建立了内热式移动床反应器内煤热解过程综合数学模型，重点研究了热载气体流量和床层高度对煤热解过程的影响规律，为鲁奇三段炉优化煤热解工艺提供理论指导。本项目的研究对于发展移动床气固反应器数值模拟方法，认识反应器内复杂工艺过程的机理，提高移动床反应器设计水平，具有重要的学术意义和应用价值。