X-ray microtomography investigations on deep bed filtration

在该项目的实验调查中，将使用X射线微层析成像技术来检查深层过滤过程。这些研究的主要目标将是增强对沉积机理的了解，并定量了解作为过滤参数的函数的过滤器中沉积物的浓度分布。在项目的第一阶段，我们开发了一种技术来量化具有沉积颗粒的深床过滤器断层图像中不同相的含量。该技术允许对断层图像的每个单个体素中的多组分系统的不同种类的部分进行量化。因此，可以分析小于层析成像装置的分辨率极限的沉积。在项目的第二阶段，我们将详细分析与通常的沉积剖面的偏差，这些沉积剖面的浓度在滤床高度上呈指数衰减。通过对用于过滤的悬浮液中颗粒尺寸分布的定制组成，我们将尝试检验这样的假设，即所观察到的沉积背景随时间增长是悬浮液的多分散性的结果。此外，在第一个项目阶段，已经进行了关于过滤器内气泡影响的第一次调查。由于它们的技术相关性，我们计划进一步开展这些研究，以量化气泡对过滤过程的重要性。作为该项目的一个总体目标，我们打算基于有关沉积物和滤床几何形状的微观信息，更好地了解深层过滤中的沉积动力学及其对最重要的工艺参数的依赖。

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.