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Experimental investigation and modelling of coalescence and agglomeration for spray drying of suspensions

悬浮液喷雾干燥聚结和团聚的实验研究和建模

基本信息

批准号：
121820773
负责人：
Professor Dr.-Ing. Martin Sommerfeld
金额：
--
依托单位：
Institut für Verfahrenstechnik
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2009
资助国家：
德国
起止时间：
2008-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/121820773?language=en
关键词：
Experimental investigation modelling coalescence agglomeration

项目摘要

The main objective of the research project is related to the modelling of droplet collisions under conditions relevant for spray drying processes, thus for suspension and solution droplets with different drying stage. Consequently, the collision of viscosity dominated droplets and the collision outcome as well as the collision of high viscous droplets with the resulting agglomeration is considered. As a result, the properties of the produced powders, e.g. particle size distribution and agglomerate structure shall be described. The developed models will be implemented in an inhouse Euler/Lagrange code in order to provide a tool for allowing the design and optimisation of stray drying processes.For the realisation of the project goals further measurements of high viscous droplet collisions will be carried out in the last project period. Here a viscosity range up to about 6 Pa s can be achieved with the new droplet generators developed during the last project period. At such high droplet viscosity a partial penetration is expected, yielding binary agglomerates. The penetration depths will be measured by high-speed cameras and summarised using the relevant dimensionless parameters. On the basis of extensive parameter studies (i.e. impact parameter, collision velocity and viscosity ratio) the dependencies will be elaborated and combined to appropriate modelling concepts. On this basis the penetration and structure model of Sommerfeld and Stübing (2012) will be reviewed and adapted according the new findings.The developed droplet collision models as well as a drying model will be implemented in the inhouse Euler/Lagrange code (FASTEST/Lag 3D). For validation, measurements at the modified laboratory spray dryer will be conducted, which is at the inlet equipped with two fan-type atomisers. The separation of the atomisers may be varied in order to determine the spray interaction region. In the near field of the spray nozzles a change of the droplet size due to droplet collisions yielding coalescence or separation, are recorded via optical measurements. This is possible since the fan sprays are rather dilute, so that optical methods, such as high-speed cameras, can be utilised to determine all relevant parameters. Using large nozzle separations spray interaction takes place in the far field where the droplets have dried to a large extent so that agglomeration will be observed. The agglomeration process will be again recorded by high-speed imaging. Moreover, powder probes will be sampled at the end of the test section for allowing a size and shape analysis. After the validation, a simulation tool will be available for predicting the powder properties of spray drying processes.

该研究项目的主要目标是对喷雾干燥过程相关条件下的液滴碰撞进行建模，从而对不同干燥阶段的悬浮液和溶液液滴进行建模。因此，考虑了粘性主导液滴的碰撞和碰撞结果以及高粘性液滴与由此产生的团聚的碰撞。因此，所生产的粉末的性能，例如应描述粒度分布和团聚结构。开发的模型将在内部欧拉/拉格朗日代码中实施，以便提供允许设计和优化杂散干燥过程的工具。为了实现项目目标，将在最后一个项目期间进行高粘性液滴碰撞的进一步测量。使用上一个项目期间开发的新型液滴发生器可以实现高达约 6 Pa s 的粘度范围。在如此高的液滴粘度下，预计会部分渗透，产生二元附聚物。穿透深度将通过高速摄像机测量并使用相关无量纲参数进行汇总。在广泛的参数研究（即冲击参数、碰撞速度和粘度比）的基础上，将详细阐述这些依赖性并将其结合到适当的建模概念中。在此基础上，Sommerfeld 和 Stübing（2012）的渗透和结构模型将根据新发现进行审查和调整。开发的液滴碰撞模型以及干燥模型将在内部 Euler/Lagrange 代码（FASTEST/Lag 3D）中实施。为了验证，将在改进的实验室喷雾干燥器中进行测量，该喷雾干燥器在入口处配备了两个风扇型雾化器。可以改变雾化器的间隔以确定喷雾相互作用区域。在喷嘴的近场中，通过光学测量记录由于液滴碰撞产生聚结或分离而导致的液滴尺寸的变化。这是可能的，因为扇形喷雾相当稀，因此可以利用高速摄像机等光学方法来确定所有相关参数。使用大喷嘴间距，喷雾相互作用发生在远场，其中液滴已很大程度上干燥，因此可以观察到团聚。团聚过程将被高速成像再次记录下来。此外，粉末探针将在测试部分的末端取样，以进行尺寸和形状分析。验证后，模拟工具将可用于预测喷雾干燥过程的粉末特性。