Structural Analysis of Nonwovens for Cleanable Filters

Research project P 14597 Structural analysis of nonwovens for cleanable filters Wilhelm HÖFLINGER 27.11.2000 The utilization of filter devices equipped with dry-operating cleanable textile filter media is one of the most favoured separation techniques for fine dust. The automatic dust removal from the surface of the filter medium combined with the generation of the filter elements are important criteria of assessment for the operational behaviour of cleanable filters. In connection with this to date there is no mathematical algorithm to describe the long-term behaviour respectively the clogging behaviour of filter media which substantially influences the operating costs. The state of technological research today shows that the selection of a suitable filter medium and the determination of the operational parameters (e.g. filter area load, pressure loss, etc.) are only feasible on the basis of experimental experiences or by empirical knowledge which was gained by trial and error. Since the cleaning behaviour of the textile filter material is obviously influenced by the surface condition of the filter medium it is intended to formulate one or if required some characteristic values which can be utilized to describe the surface conditions quantitatively. The specification of these structure parameters shall be the result by the observation of the filter surface with computer added image analysis. Subsequently the cleaning behaviour of the filter medium shall be investigated by utilization of the filter medium as filter sample in the institute-owned modified VDI-conforming filter test apparatus. In addition to this the correlation between the newly defined characteristic values which describe the surface conditions of the filter medium and those parameters which influence the thermal finishing process (calendering, singeing, etc.) shall be formulated. In this manner it is possible for the first time to produce specific (made-to-measure) filter media by carefully directed procedures which especially change the surface condition of the thermally treated filter media during the finishing process. The production of such thermally treated filter media can be controlled and optimized by the newly defined surface structure parameters. 1st - The solution of the fundamental mechanisms between the surface structure of the filter medium, the manufacturing process of this structured surface and the filtration respectively cleaning behaviour of the surface- treated filter medium, 2nd - the prolongation of the filtration periods and simultaneously the reduction of the number of filtration cycles by the utilization of specially finished textile filter materials in cleanable filters and 3rd - the systematic manufacture of optimal cleanable filter media, are the aims of this research project.