Clarification of segregation behavior of polydisperse, moist bulk materials with different wetting properties in discontinuous mixing processes

阐明不连续混合过程中具有不同润湿特性的多分散、潮湿散装材料的偏析行为

基本信息

批准号：
313759864
负责人：
Professor Dr.-Ing. Hermann Nirschl
金额：
--
依托单位：
Arbeitsgruppe Verfahrenstechnische Maschinen (VM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/313759864?language=en
关键词：
Clarification segregation behavior polydisperse moist

项目摘要

Each solid mixing process is aimed at balancing concentration differences and achieving maximum homogeneity. As a result of various physical material properties of the feed components, e.g. particle size or solid density, and the related different particle mobilities, maximum homogeneity cannot always be achieved. By adding small amounts of liquid, these different mobilities can be compensated by interparticle liquid bridge forces. However, liquid bridge forces depend largely on the amounts of liquid and wetting properties of the particle systems, which means that liquid addition does not necessarily reduce segregation. If hydrophilic components need to be mixed with hydrophobic components, for example, the addition of water can cause the opposite effect. The water accumulates selectively in the hydrophilic component, such that inhomogeneous agglomerates are formed, which are mainly composed of material with good wetting properties. Accordingly, it cannot generally be assumed that the addition of liquid minimizes segregation. This has to be assessed individually depending on the product characteristics. It is the subject of this research to understand the relationship between occurring segregation mechanisms and their reduction by the addition of liquid using numerical simulation. For this purpose, extensive models of liquid bridge force, liquid distribution, and moist-dry particle contact shall be developed and implemented in the discrete element method. By using the Fokker-Planck equation, the mixing and segregation mechanisms changed as a result of liquid addition can be assessed on the basis of dispersion and transport coefficients. These coefficients, in turn, provide suitable parameters for transferability to technically relevant material systems with high particle numbers, which cannot be simulated numerically. Finally, a simulation tool will be available to numerically investigate segregating, wet solids in mixing processes. These results can be transferred to technical mixing processes by using appropriate parameters.

每个固体混合过程旨在平衡浓度差异和达到最大均匀性。由于饲料成分的各种物理材料特性，例如粒度或固体密度以及相关的不同粒子迁移率，最大均匀性不能总是实现。通过添加少量液体，这些不同的迁移率可以通过颗粒液桥力来补偿。但是，液体桥力在很大程度上取决于粒子系统的液体和润湿特性的量，这意味着液体添加不一定会减少分离。例如，如果需要将亲水性成分与疏水成分混合，则加水可能会引起相反的效果。水在亲水性成分中有选择地积聚，因此形成了不均匀的聚集酯，主要由具有良好润湿特性的材料组成。因此，通常不能假定添加液体可以最大程度地减少种族隔离。必须根据产品特性对此进行单独评估。这项研究的主题是通过使用数值模拟来了解发生的分离机制与它们减少液体之间的关系。为此，应在离散元素方法中开发和实现液体桥力，液体分布和湿干颗粒接触的广泛模型。通过使用Fokker-Planck方程，可以根据分散和运输系数评估混合和隔离机制因液体添加而变化。这些系数反过来提供了合适的参数，以转移到具有高粒子数量的技术相关材料系统，而该系统无法通过数值进行模拟。最后，将可以使用一个模拟工具来研究混合过程中的分离湿固体。这些结果可以通过使用适当的参数将其转移到技术混合过程中。