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气固两相流模型及细粒煤振动流化床的模拟应用

Gas-solid two-phase flow model and its applicationin vibrated fluidized bed of fine coal

  • 摘要: 为深入认识振动流化床床层微观结构,模拟、预测和优化控制气固两相流动和传热行为,基于对床层时空多尺度不均匀结构特性的分析,全面综述和分析了振动流化床模拟广泛采用的气固两相流模型的类型、特点、优缺点及应用现状,并对未来发展进行了展望。结果表明:拟流体模型模拟结果接近于工程实际,离散颗粒模型能跟踪颗粒运动轨迹,拟颗粒模型能揭示床层非均匀结构和求解复杂流场问题,无统一的模型全面描述气固两相流动;双流体模型和离散颗粒模型能较好地模拟床层空隙率、固体颗粒浓度和速度、颗粒分布均匀性和气压稳定性,模型和参数的选择非常关键,基本方程的求解有难度,与工程实际还有差距;引入非线性理论表征多流态流型与床层不均匀结构,研究振动流化床能量传播行为和离析混合模式控制机制是未来的发展方向。

     

    Abstract: In order to understand the microstructure of vibrated fluidized bed and to simulate,predict and optimize the control of gas-solid two-phase flow and heat transfer behavior,based on the analysis of the spatio-temporal heterogeneous structure characteristics of the bed,the types,characteristics,advantages,disadvantages and application status of gas-solid two-phase flow models widely used in vibrated fluidized bed simulation are reviewed and analyzed,and the future development is prospected.The results show that:the simulation results of the pseudo-fluid model are close to the engineering practice,the discrete particle model can track the particle trajectory,the pseudo-particle model can reveal the non-uniform structure of the bed and solve the complex flow field problems,there is no unified model to describe gas-solid flow in a comprehensive way.The two-fluid model and the discrete particle model can well simulate the porosity,solid particle concentration and velocity,particle distribution uniformity and pressure stability of the bed.The choice of model and parameters is very important,and it is difficult to solve the basic equation,so there is still a gap with the engineering practice.The introduction of non-linear theory to characterize the multi-flow regime and the non-uniform structure of the bed,and the study of the energy transfer behavior and the control mechanism of segregation and mixing modes in the vibrated fluidized bed are the future development directions.

     

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