Experimental and numerical analysis for the derivation of a dynamic solid bed model in rotary drums considering mixing and segregation processes

在回转窑的过程模拟中，经常会出现瞬时启动过程。在此过程中，由于填充度和物料性质的变化，在床内产生了分离效应和不同的运动行为。由于不完全混合，热渗透到床层是暂时的，从而在核心和表面之间出现温差。在这个项目中，将利用两个研究所现有的经验、实验和工具来模拟单分散和多分散固体床在回转窑横截面上的分离和混合行为。该模型描述了床层内的瞬时换热以及床层内的温度分布与颗粒尺寸、物料性质和操作参数的关系。然后将动态模型(单元操作模块)转换为相应的流程图模拟。工作的起点是由两个研究小组之一合作开发的针对稳态情况的几个实验和由此得出的唯象模型。将这一知识转移到颗粒流系统，以时间分辨的方式反映瞬时内和外边界条件的影响，将由第二个合作伙伴使用基于粒子的离散单元(DEM)模拟进行，该模拟允许对基本物理过程进行严格描述。这些模拟将通过已有的稳态实验和在计划中的项目内进行的新的瞬变调查来验证。所获得的结果将被引入正在开发的单元操作模块，并将用于补充和修改已知的关系和方程式。

In a process simulation for rotary kilns always transient start-up procedures appear. During the process segregation effects and different motion behaviors arise inside the bed, which are caused by the change of the filling degree and the material properties. The heat penetration into the bed is transient due to the incomplete mixing, whereby a temperature difference between the core and the surface is emerged. Furthermore the transient behavior occurs by the change in mass flow, the type of fuel, the flame control and the energy input.In this project, the existing experiences, experiments and tools of the two research institutes will be used to model the segregation and mixing behavior of mono and poly-disperse solid beds in the cross section of a rotary kiln. This model will represent the transient heat transfer into the bed and the temperature distribution in the bed in dependence of the particle size, the material properties and the operational parameters. The dynamic model (unit operation module) will then be converted into a corresponding flow sheet simulation.Starting point of the work are several experiments and phenomenological models derived therefrom, which were developed for steady state situations by one of the two research groups cooperating on this topic. The transfer of this knowledge to particulate flow systems, reflecting in a time resolved manner the effect of transient inner and outer boundary conditions, will be carried out by the second partner, using of particle based Discrete Element (DEM) simulations, which allow a rigorous description of the underlying physical processes. These simulations will be verified with already available steady state experiments and new, transient investigations conducted within the planned project. The results obtained will be introduced into the unit operation module under development and will be used to complement and modify the already known relations and equations.