X-ray microtomography investigations on deep bed filtration

在项目实验调查中，将使用x射线显微断层扫描来检查深床过滤过程。这些研究的主要目标将是加强对沉积机制的了解，并定量了解过滤器中沉积物的浓度曲线作为过滤参数的函数。在项目的第一阶段，我们开发了一种技术，可以在沉积颗粒的深床过滤器层析图中量化不同相的含量。该技术允许在层析图的每个单个体素中对多组分系统中不同物种的部分进行量化。因此，可以分析小于层析成像装置分辨率限制的沉积物。在项目的第二阶段，我们将详细分析与通常沉积剖面的偏差，其浓度随滤床高度呈指数衰减。通过对用于过滤的悬浮液中粒径分布的调整，我们将尝试检验这样一个假设，即观察到的沉积背景，随着时间的推移而增长，是悬浮液多分散性的结果。此外，在项目的第一阶段，对过滤器中气泡的影响进行了首次调查。由于它们的技术相关性，我们计划进一步开展这些调查，以量化气泡对过滤过程的重要性。作为该项目的总体目标，我们打算根据沉积物和过滤层几何形状的微观信息，加深对深床过滤中的沉积动力学及其对最重要过程参数的依赖的理解。

Within the project experimental investigations, using X-ray microtomography will be used to examine deep bed filtration processes. The major goal of these investigations will be an enhanced understanding of the deposition mechanisms and a quantitative understanding of the concentration profiles of the deposits in the filter as a function of filtration parameters.Within the first phase of the project, we have developed a technique to quantify the content of different phases within a tomogram of a deep bed filter with deposited particles. This technique allows the quantification of the portion of different species of a multi-component system in each single voxel of the tomogram. Thus, it became possible to analyze depositions smaller than the resolution limit of the tomography setup. Within the second phase of the project, we will analyze in detail deviations from the usual deposition profiles with an exponential concentration decay over the height of the filter bed. By tailored composition of the particle size distribution in the suspensions used for filtration, we will try to test the hypothesis that the observed deposition background, growing in time, is a result of the polydispersity of the suspensions. In addition, first investigations concerning the influence of air bubbles in the filter have been performed in the first project phase. Due to their technical relevance, we plan to develop these investigations further to quantify the importance of air bubbles for the filtration process. As an overall goal of the project, we intend to gain an enhanced understanding of the deposition kinetics in deep bed filtration and its dependence on the most important process parameters based on microscopic information about deposits and filter bed geometry.