Processing of high solids content pastes with evolving rheology

在联合利华美容和个人护理（BPC）产品组合中，可以找到具有广泛流变特性的产品，这些产品可以通过其特定的微观结构来定义，包括各向同性溶液，层状结构液体和高固体含量的糊状。为了更好地理解各向同性流体的加工领域，正在积极开展许多研究，但在高固含量糊状物领域的研究相对有限。拟议的研究项目旨在更好地了解该系统的处理挑战。BPC产品的生产是通过按规定的顺序、规定的添加速率和控制的温度曲线连续添加原材料来实现的。因此，在BPC产品的整个生产过程中，有两个属性会发生变化：(1)批容器内液位的增加；(2)每个中间阶段的流变特性的变化，受成分、温度和加工条件的影响。这两个属性将影响可实现的混合强度和效率，以及容器内和任何相关管道的流动特性。这反过来又会影响产品质量、能源需求和整体流程优化。此外，制造BPC产品的许多过程涉及利用再循环回路来实现主容器内自上而下的均匀性和/或产品内原材料的有效掺入（真空下添加粉末）。拟议的研究项目旨在探索高固体含量糊状物的这三种影响（增加液位，流变特性变化和微观结构演变），通过使用动态扭矩测量，开发功率消耗表达式作为容器内液位的函数和流动表征技术，如正电子发射颗粒跟踪（PEPT）和颗粒图像测速（PIV）来实现。此外，该项目将探索计算流体动力学（CFD）领域，以确定一种方法，可以在整个过程中跟踪容器液位和产品流变的演变，并使用实验结果进行验证。

Within the Unilever Beauty and Personal Care (BPC) portfolio, products with a wide range of rheological properties can be found which can be defined by their specific microstructure which includes isotropic solutions, lamellar structured liquids and high solids content pastes. Much research is actively being conducted to gain better understanding in the area of processing of isotropic fluids, yet comparatively limited research is dedicated to the field of high solids content pastes. The proposed research project aims to gain better understanding of the processing challenges for this system.The manufacture of BPC products is achieved through the sequential addition of raw materials in a defined order, specified rates of addition and controlled temperature profiles. Thus, there are two attributes which vary throughout the manufacturing process of BPC products: (1) increasing fluid level within the batch vessel and (2) variations in rheological properties for each of the intermediate stages, affected by the composition, temperature and processing conditions. These two attributes will impact the achievable mixing inten sity and efficiency, as well as flow characteristics within the vessel and any associated pipework. This, in turn, affects product quality, energy requirements and overall process optimisation. Furthermore, many processes for the manufacture of BPC products involve utilisation of recirculation loops to achieve both top-to-bottom homogeneity within the main vessel and/or efficient incorporation of raw materials within the product (powder additions under vacuum).The proposed research project aims to explore these three effects (increasing fluid level, variations in rheological properties and microstructure evolution ) for high solids content pastes, achieved through use of dynamic torque measurements, the development of power draw expressions as a function of fluid level in-vessel and flow characterisation techniques, such as positron emission particle tracking (PEPT) and particle image velocimetry (PIV). In addition, the project will explore the computational fluid dynamics (CFD) space to identify an approach that would allow tracking the evolution of the vessel level and product rheology throughout the process, using experimental results for validation .