Characterization of the fluid dynamics and discrete particle modelling of a novel spouted bed apparatus

本论文的主要目的是对一种新型狭缝式喷动床内的流体动力学特性进行实验和理论研究。喷动床为气-固系统的紧密接触提供了非常有效的可能性，这对于细的和多分散的粉末的形成、处理和加工是至关重要的。此外，在喷动床中，颗粒可以流化，这在常规流化床中是不可能的，特别是当颗粒具有宽的尺寸分布时，当它们是小而轻或非常大时，当它们是强烈非球形时或当它们是粘性的时。喷动床的可调供气系统可防止颗粒在床关闭时排出，并允许在操作过程中清洁床。稳定的操作模式将根据喷动床中压力波动的测量和傅立叶分析获得的频谱来确定。这些稳定模式将被压缩到政权地图。为此，喷射床的尺寸、工艺参数以及颗粒系统将变化。特别是气体流量和有效的自由气体入口面积通过旋转的气体供应气缸的影响将被调查。当得到这些结果后，将与其它喷动床和流化床结构的稳定操作状态图进行比较。特别地，将采用考虑相之间的耦合的离散颗粒模型（discrete particle model，简称DEM）来优化设备几何形状。应用该方法的优点是有机会计算装置的最佳设计，而模拟将根据一些选定的实验进行验证。除了在干燥条件下的研究外，还将探索在潮湿条件下喷动床的流动、传热和传质，即通过用喷嘴喷射液滴，其可用于颗粒的造粒和包覆。在这种情况下，也将使用该按钮。

The goal of the planned research is the experimental and theoretical investigation of the fluid dynamics in a novel slit-shaped spouted bed with two horizontal gas inlets and adjustable gas supply. Spouted beds offer very effective possibilities for intensive contacting of gas-solid systems, which is of prime importance for the formation, treatment and processing of fine and poly-disperse powders. Furthermore, in spouted beds particles can be fluidized, which would not be possible in conventional fluidized beds, especially when the particles have a broad size distribution, when they are small and light or very large, when they are strongly non-spherical or when they are sticky. The adjustable gas supply system of the spouted bed prevents the discharge of particles when the bed is switched off and allows for cleaning the bed during operation.The stable modes of operation will be determined based on measurements of the pressure fluctuations in the spouted bed and frequency spectra obtained from Fourier analysis. These stables modes will be condensed into regime maps. To this end, the dimensions of the spouted bed, the process parameters, as well as the particulate system will be varied. Especially the influence of the gas flow rate and the effective free gas inlet area through the rotation of the gas supply cylinders will be investigated. When these results have been obtained, a comparison with the stable operation regime maps of other spouted and fluidized bed constructions will be made. In particular a discrete particle model (DPM) that takes into account the coupling between the phases will be employed to optimize the apparatus geometry. The advantage of applying the DPM is the opportunity to calculate an optimal design of the apparatus, while the simulations will be validated based on a few selected experiments. In addition to the investigations under dry conditions, the flow, heat and mass transfer of a spouted bed under wet conditions will be explored, i.e. by spraying droplets with a nozzle, which can be used for granulation and coating of particles. Also in this case the DPM will be used.