On the influence of an added fraction of hygroscopic salt particles on the operating behaviour of surface filters for dust separation by moisture-induced deliquescence and efflorescence

作为规则，对表面过滤器的操作行为进行有针对性的操作的基础总是归因于这样一个事实，即良好的性能在长周期时间内自我调整。这是通过在过滤阶段缓慢增加压降和在再生后较低的残余压降来获得的。从技术上讲，这种状态可以通过所谓的原料气调节来实现。在这里，通过添加添加剂或引入能量来选择性地改变飞行阶段或粉尘饼中的颗粒特性。众所周知，颗粒的粘附力一般随着气体湿度的增加而增强。在再生过程中，滤饼中颗粒粘附性的增加减少/防止了滤饼在过滤阶段的压缩，并促进了滤饼层的粘合，而滤饼层与过滤介质表面之间的粘附性的增加阻碍了再生过程中灰饼的脱离。这两种效应的单独影响不可能通过过滤过程中气体湿度的永久变化来实现。吸湿盐颗粒的潮解和风化特性可以被认为是滤饼中粉尘颗粒之间形成固体桥的可能性，这种特性可以由气体湿度的瞬时增加引起。有了这种原料气调节概念，理论上可以灵活地、有针对性地加强滤饼内的粘聚力，而不会伴随着改变滤饼层和过滤介质之间的粘附性。在拟议的研究项目范围内，正在进行实验和理论研究，以期通过定期投加吸湿盐颗粒，对表面过滤器的运行行为产生影响，并在尘饼中增加一部分具有潮解和风化特性的吸湿盐颗粒。观察到的积极效果将通过在实验室过滤器测试仪上用针刺毡的标准测试过滤器进行系统检查来检查。此外，对该方法可能的技术实施的临界边界条件将通过扩展筛选试验进行实验研究。在此基础上，对新的调理过程进行了定量评价。

The basis for targeted manipulation of the operating behaviour of surface filters is, as a rule, always attributable to the fact that a favorable performance adjusts itself at long cycle times. These are obtained by a slow increase in pressure drop during the filtration phase and by a low residual pressure drop after the regeneration. Technically, such states can be realized by so-called raw gas conditioning. Here the particle characteristics in the flight phase or in the dust cake are selectively modified by dosing additives or introducing energies. It is known that the particle adhesion is generally strengthened with increasing gas humidity. While an increase of particle adhesion in the dust cake reduces/prevents the compression of the dust cake in the filtration phase and promotes the cohesion of the cake layer during the regeneration, an increase of adhesion between the cake layer and the filter medium surface impedes the detachment of the dust cake during the regeneration. A separate influence of these two effects is not possible by a permanent change of the gas humidity during the filtration.The deliquescence and efflorescence properties of hygroscopic salt particles, which can be induced by a transient increase in gas humidity, can be considered as possibilities for the formation of solid bridges between dust particles in the filter cake. With this raw gas conditioning concept, a flexible and targeted strengthening of the cohesion in the filter cake without an accompanied modification of the adhesion between the cake layer and the filter medium is theoretically possible. Within the scope of the proposed research project, it is being studied experimentally and theoretically, which effects an added fraction of hygroscopic salt particles with their deliquescence and efflorescence properties in the dust cake has on the operating behaviour of surface filters, in particular with the aim of a targeted manipulation of the operating behaviour of surface filters by periodic dosing of hygroscopic salt particles. The observed positive effects will be checked by systematic examinations with standard test filters from needle felts on a laboratory filter testing apparatus. In addition, critical boundary conditions for a possible technical implementation of the method are to be investigated experimentally by extended screening tests. Based on this, a quantitative assessment of the new conditioning process is made.