权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

每个固体混合过程都旨在平衡浓度差异并达到最大的均匀性。由于进料组分的各种物理材料特性，例如粒度或固体密度，以及相关的不同颗粒迁移率，并不总是能够实现最大的均匀性。通过加入少量的液体，这些不同的流动性可以通过粒子间的液体桥力来补偿。然而，液桥力在很大程度上取决于液体的数量和颗粒系统的润湿特性，这意味着添加液体不一定会减少偏析。例如，如果亲水组分需要与疏水组分混合，则水的加入会产生相反的效果。水选择性地聚集在亲水组分中，形成不均匀的团聚体，主要由润湿性能好的材料组成。因此，一般不能假定液体的加入使分离最小化。这必须根据产品特性单独评估。本研究的主题是通过数值模拟来了解发生的偏析机制与通过添加液体来减少偏析机制之间的关系。为此，应在离散元法中建立和实现广泛的液桥力、液分布和干湿颗粒接触模型。利用Fokker-Planck方程，可以根据色散系数和输运系数来评价由于液体加入而改变的混合和分离机制。这些系数反过来又为具有高颗粒数的技术相关材料系统的可转移性提供了合适的参数，这是无法用数值模拟的。最后，模拟工具将可用于数值研究分离，湿固体在混合过程。这些结果可以通过使用适当的参数转移到技术混合过程中。