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.

研究项目的主要目的与在与喷雾干燥过程相关的条件下的液滴碰撞建模有关，因此对于具有不同干燥阶段的悬浮液和溶液液滴。因此，考虑了粘度主导的液滴的碰撞以及碰撞结果以及高粘性液滴与所产生的聚集的碰撞。结果，产生的粉末的性质，例如应描述粒度分布和集聚结构。开发的模型将在Inhouse Euler/Lagrange代码中实施，以提供一种工具，以设计和优化流浪干燥过程。对于项目目标的现实，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。在上一个项目期间，新的液滴发生器可以实现粘度范围可达约6 pa s。在如此高的液滴粘度下，预计会局部穿透，从而产生二进制聚集物。穿透深度将通过高速相机测量，并使用相关的无量纲参数进行汇总。基于广泛的参数研究（即影响参数，碰撞速度和粘度比），依赖项将被详细说明并结合到适当的建模概念。在此基础上，将根据新发现对Sommerfeld和Stübing（2012）的渗透和结构模型进行审查。为了进行验证，将在改良实验室喷雾干燥机处进行测量，该烘干机在配备两个风扇型原子剂的入口处进行。为了确定喷雾相互作用区域，原子异构体的分离可能会变化。在喷射喷嘴的近场中，由于液滴碰撞而产生的合并或分离引起的液滴大小的变化是通过光学测量记录的。这是可能的，因为风扇喷雾剂相当稀释，因此可以利用光学方法（例如高速相机）来确定所有相关参数。使用大型喷嘴分离喷雾相互作用发生在液滴在很大程度上干燥的远场，以便观察到聚集。聚集过程将通过高速成像再次记录。此外，将在测试部分的末尾采样粉末问题，以允许大小和形状分析。验证后，将可以使用一个模拟工具来预测喷雾干燥过程的粉末性能。