Fundamental mechanisms of soluble dust cake components penetration through gas cleaning filter media

在通过表面过滤器的气体清洁过程中，灰尘分离的质量主要由过滤介质上的颗粒结构（滤饼）决定。虽然关于惰性颗粒过滤的研究已经导致这些过程的排放和能源消耗的大幅减少，但在非理想系统中过滤期间发生的基本机制，例如在可溶性颗粒和液体气溶胶存在下的粉尘过滤，仍然是未知的。在该项目的框架内，正在研究气体清洁过程中可溶性尘饼成分通过表面过滤器渗透的基本机制。在项目的第一阶段，确定了一个合适的材料系统，研究和测试了分析过滤器的方法，并进行了关于可溶性滤饼短期暴露于水滴的影响的实验。因此，研究了盐颗粒渗透的第一阶段，液体的吸收和过滤器表面上可溶性颗粒的重排，以及其对过滤器的操作行为（压降）的影响。该项目新阶段的重点是，在现有结果的基础上，将调查暴露于水滴期间操作模式的影响以及可溶性和不溶性颗粒的滤饼成分对渗透的影响。因此，将系统地研究与连续暴露相比，间歇暴露于水滴的影响。此外，还将分析盐的渗透如何取决于原始干燥滤饼中可溶性和不溶性颗粒的比例。为了对过滤器进行详细分析，实施了同时观察过滤器上游和下游的摄像机系统，以观察颗粒的溶解和重排以及溶液的膜形成排水，并将其与观察到的操作行为（压降、排水）相关联。此外，在项目的最后阶段，将通过调查盐通过具有非常不同的结构参数的过滤器（深层过滤）的渗透来检查观察结果和结论的局限性。因此，也将检查现有模型的适用性，例如来自油雾过滤应用的跳跃和通道模型。在第二个项目阶段结束时，将明确哪些机制决定可溶性颗粒通过过滤介质的渗透，以及它们如何取决于操作模式，滤饼中可溶性颗粒的比例和过滤器的结构影响过滤器的操作行为（压降，排水量，分离效率）。

The quality of dust separation during gas cleaning processes by surface filters is strongly dominated by the particle structures on the filter medium, the filter cake. While research concerning the filtration of inert particles has already lead to major reductions in emissions and energy consumption by these processes, the fundamental mechanisms taking place during the filtration in a non-ideal system, such as dust filtration in the presence of soluble particles and liquid aerosol are still unknown. Within the framework of this project, the fundamental mechanisms of the penetration of soluble dust cake components through surface filters during gas cleaning are being investigated. In the first project phase, a suitable material system was identified, methods to analyze the filters were studied and tested and experiments concerning the influence of short-term exposure of soluble filter cakes to water droplets were carried out. Therefore, the first phase of the penetration of the salt particles, the uptake of liquid and rearrangement of the soluble particles on the filter surface, and its effect on the operating behavior (pressure drop) of the filter was investigated. The focus of this new phase of the project, building on the present results, will be the investigation of the influence of the operating mode during the exposure to water droplets and the influence of the composition of the filter cake of soluble and insoluble particles on the penetration. Therefore it will be systematically investigated, which effect an intermittently exposure to water droplets compared to a continuous exposure has. Additionally it will be analyzed how the penetration of the salt depends on the proportion of soluble and insoluble particles in the originally dry filter cake. For a detailed analysis of the filter, a camera system observing the filter upstream and downstream simultaneously is implemented to observe the dissolving and rearranging of the particles and the film formation drainage of the solution and correlate it to the observed operating behavior (pressure drop, drainage). Furthermore, during the final phase of the project, the limit of the observations, and conclusions will be examined, by investigating the penetration of salt through filters with very different structural parameters (depth filtration). Therefore, also the applicability of already existing models such as the jump-and-channel-model from oil-mist filtration applications will be examined. At the end of this second project phase it will be clear, which mechanisms determine the penetration of soluble particles through filter media and how they depending on the operating mode, the proportion of soluble particles in the filter cake and the structure of the filter affect the operating behavior of the filter (pressure drop, draunage, separation efficiency).