Analysis of fluidization and shear conditions in rotary-fluidized beds under dry and wet conditions

干湿条件下旋转流化床流化和剪切条件分析

• 批准号: 413588004
• 负责人: Professor Dr.-Ing. Sergiy Antonyuk
• 金额: --
• 依托单位: Lehrstuhl für Mechanische Verfahrenstechnik (MVT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413588004?language=en
• 关键词: Analysis; fluidization; shear; conditions; rotary

In this project, the particle dynamics in dense sheared granular flows should be described by taking the example of a rotor granulator. For this aim the gas-particle flow will be characterized by means of the Discrete Element Method (DEM) coupled with the Computational Fluid Dynamics (CFD), whereby the Magnetic Particle Tracking (MPT) will be used for the validation of the simulations. The application of DEM based simulations will provide a detailed insight in the particle dynamics, interactions and mechanical stresses (e.g. particle rotation, collision velocities, forces and frequencies). Mathematical models describing the influence of process and material parameters on the dynamics of single particles in the granulation and coating should be developed and implemented in the DEM. The central element of this project is the characterization of the influence of the presence of a liquid on the particle dynamics by experimentally validated simulations. A liquid bridge model, which contains the capillary and viscous forces acting between wetted particles during normal and oblique impacts, should be developed and implemented. The MPT method, used for the capturing of the three-dimensional movement of the particles, is a highly innovative method for characterization and monitoring of dense granular flows (for spherical and non-spherical particles). So far, the particle movement in dense granular flows could be well characterized with very expensive experimental setups, such as Positron Emission Particle Tracking (PEPT). With the MPT method, used in this project, for the first time not only particle velocities and accelerations, but also the particle rotation can be measured, which cannot be captured or sufficiently resolved with other available methods. The measuring range of the MPT has to be extended to smaller particle sizes. This will be achieved by redesign of the measurement set-up and improved shielding against external magnetic fields, including the earth's magnetic field. Marker particles with properties tailored to physical properties of bed particles should be manufactured by means of fluidized bed coating and used in the measurements. On the basis of spray granulation and coating experiments the results from the simulations and experimental studies will be evaluated with respect to the granule growth rate and the coating quality.

在本项目中，以转子造粒机为例来描述密集剪切颗粒流中的颗粒动力学。为此，将采用离散元法（DEM）与计算流体动力学（CFD）相结合的方法来表征气粒流，其中磁颗粒跟踪（MPT）将用于验证模拟。基于DEM的模拟应用将提供粒子动力学，相互作用和机械应力（例如粒子旋转，碰撞速度，力和频率）的详细见解。应该在DEM中开发和实施描述工艺和材料参数对造粒和涂层中单个颗粒动力学影响的数学模型。本项目的核心内容是通过实验验证的模拟来表征液体的存在对粒子动力学的影响。应该开发和实施一种液体桥模型，该模型包含了在正常和倾斜碰撞中作用于湿颗粒之间的毛细力和粘性力。MPT方法用于捕获颗粒的三维运动，是一种高度创新的方法，用于表征和监测致密颗粒流（用于球形和非球形颗粒）。到目前为止，密集颗粒流中的颗粒运动可以通过非常昂贵的实验装置来很好地表征，例如正电子发射粒子跟踪（PEPT）。本项目中使用的MPT方法不仅可以测量粒子的速度和加速度，而且还可以测量粒子的旋转，这是其他可用方法无法捕获或充分解决的问题。MPT的测量范围必须扩展到更小的颗粒尺寸。这将通过重新设计测量装置和改进对外部磁场（包括地球磁场）的屏蔽来实现。具有与床层颗粒物理特性相适应的标记颗粒应通过流化床涂层制造并用于测量。在喷雾造粒和涂层实验的基础上，对模拟和实验研究的结果进行了颗粒生长速度和涂层质量的评价。