Interactions between the structure of the filtering layer and the filtration kinetics during the clogging phase in the dust separation with fibrous filter media up to the beginning of the cake-forming filtration

一种新的、清洁的表面过滤介质总是从初始阶段开始，在初始阶段中，粉尘分离可以用给定介质的深度过滤原理来描述。术语过滤动力学是指整个过滤层的分离效率的时间行为，它既包括给定的介质，也包括介质中沉积的颗粒。如果在给定过滤介质上进行足够长的时间的粉尘分离，则在完成堵塞阶段后形成粉尘饼，这通常是一个渐进的过程。一个完全形成的尘饼，除了饼的核心区域，其中的填料密度几乎不再改变，在其表面有一个高度多孔的填料区域，其具有特征，稳定的高度分布的填料密度在气体流动的方向。饼表面的这个填料区域作为饼的实际，活跃的分离区，因为几乎没有任何颗粒渗透到饼的核心区域下面。因此，对于与原过滤介质有关的表面过滤，在微观层面上，在粉尘饼的高多孔填料区总是存在一种特殊的、高效的深度过滤。这种特殊的深度过滤达到了过滤动力学的动态平衡，其中过滤层意义上的主动分离区结构不再改变。因此，过滤动力学，实际上是过滤动力学的变化，在给定的清洁过滤介质上的整个粉尘分离过程可以通过描述新沉积颗粒在变化的多孔结构中沉积剖面的系统变化的机制来表征。因此，在本研究中，从一个全新的角度来看待整个过滤过程：在给定的过滤条件下，通过连续的颗粒分离，从初始的清洁过滤介质转变为一个新的、动态保存的稳定的多孔结构的给定过滤系统的活性分离区是一个连续的、系统的变化——这就是粉尘饼的活性分离区。动态重组过程背后的驱动力是过滤。研究项目将从理论上和实验上进行研究，如何通过考虑在给定过滤条件下从给定清洁纤维过滤介质中生长出来的整个多孔结构中新沉积颗粒沉积剖面的系统变化来描述过滤动力学。

A new, clean filter medium for surface filtration always starts with the initial phase in which the dust separation can be described by the principle of depth filtration in the given medium. The term filtration kinetics refers to the time behaviour of the separation efficiency of the entire filtering layer, which includes both the given medium and the deposited particles in the medium. If the dust separation on a given filter medium is carried out for a sufficiently long time, a dust cake is formed after a completed clogging phase, which is often a gradual process. A fully formed dust cake has, in addition to the core area of the cake, in which the packing density practically no longer changes, a highly porous packing area on its surface, which has a characteristic, stable height profile of the packing density in the direction of the gas flow. This packing area on the surface of the cake acts as the actual, active separation zone of the cake for the coming dust particles, since hardly any particles penetrate into the core area of the cake below. Therefore, with surface filtration which is named in relation to the original filter medium, there is always a special, highly effective depth filtration in the highly porous packing area of the dust cake on the microscopic level. This special depth filtration achieves a dynamic equilibrium of the filtration kinetics in which the structure of the active separation zone in the sense of a filtering layer no longer changes. For this reason, the filtration kinetics, actually the change in the filtration kinetics, of the overall process of dust separation on a given clean filter medium can be characterised through a description of the mechanism of the systematic change in the deposition profile of newly deposited particles in the changing porous structure. In this study, the overall filtration process is therefore viewed from a completely new perspective: There is a continuous, systematic change in the active separation zone of a given filtering system which is transformed from the initial clean filter medium via continuous particle separation under the given filtration conditions to a new, dynamically preserved stable porous structure - this is the active separation zone of the dust cake. The driving force behind the dynamic process of restructuring is the filtration. It will be theoretically and experimentally investigated in the research project, how the filtration kinetics can be described by considering the systematic change in the deposition profile of newly deposited particles in the entire porous structure that grows out of a given clean fibrous filter medium under given filtration conditions.