Incipient spray fluidized bed agglomeration at the border to coating

本工作的第一个目的是跟踪喷雾流化床团聚和涂层之间的边界，作为先进颗粒工程的关键重要性的相邻和竞争过程。我们将通过实验研究该边界附近的附聚（边界附聚），重点是它的起始期（初期附聚），其中二聚体由初级颗粒形成。最简单的团聚体结构和喷雾流化床团聚最明确的条件决定性地支持我们的第二个项目目标，这是改进的建模。在这里，我们可以利用自己的蒙特卡罗模型，这些模型是随机和离散的，能够代表微观事件和过程。我们的目标是分两个阶段从根本上改进这些模型。在第一阶段（本项目）的关键模型组成部分将进行修订，即破碎和干燥的子模型，根据单独的实验没有喷雾（破碎）或没有粘合剂的喷雾（干燥）。湿碰撞后聚集或回弹的标准也将重新讨论，但仍以正常动量耗散为基础。改进后的模型将提供直接和无条件进入结块涂层边界的机会，使政权地图不再适用。在第二阶段（继续提案），计划对汇总子模式进行更彻底的修订。基于湿点上的许多碰撞由于碰撞粒子的切向和旋转运动而不成功的假设，我们将通过初级粒子的CFD-DEM评估那些通常被忽略的运动分量，并通过使用项目第一阶段的测量结果将它们与模型中的反弹概率相关联。最终目标是操作的凝聚模型直接输入CFD-DEM，即没有目前必要的适应碰撞频率。在第二个项目期间，还将检验模型是否适用于较强的远离边界的聚集。

First aim of the present work is to track the border between spray fluidized bed agglomeration and coating, as adjoining and competitive processes of key importance for advanced particle engineering. We will investigate experimentally agglomeration in the vicinity of this border (borderline agglomeration), focusing on the starting period of it (incipient agglomeration), in which dimers are formed from primary particles. Simplest agglomerate structure and clearest conditions of spray fluidized bed agglomeration support decisively our second project aim, which is improved modeling. Here, we can capitalize on own Monte Carlo models, which are stochastic and discrete, able of representing micro-scale events and processes. The goal is to radically improve these models in two stages. In the first stage (present project) crucial model constituents will be revised, namely the sub-models for breakage and drying, based on separate experiments without spraying (for breakage) or without binder in the spray (for drying). The criterion for aggregation or rebound after wet collision will also be revisited, though still based on normal momentum dissipation. The improved model will provide direct and unconditional access to the agglomeration-coating border, making regime maps obsolete. In a second stage (continuation proposal), a still more radical revision of the aggregation sub-model is planned. Based on the hypothesis that many collisions on a wet spot are unsuccessful due to tangential and rotational motion of the colliding particles, we will evaluate those usually neglected components of motion by means of CFD-DEM on primary particles, and correlate them with a rebound probability in the model by use of measured results from the first project period. Final goal is to operate the agglomeration model with direct input from CFD-DEM, i.e. without the presently necessary adaption of collision frequency. Model applicability to stronger agglomeration far-off the border will also be tested in the second project period.