Collection Efficiency and Pressure Drop of Needle Punched Filters

Although needle punched fabrics have been used in filtration with increasing success, only meager information is available on their performance characteristics in relation to their unique structure. In this paper an experimental investigation on the performance of needle punched filters is presented. A testing apparatus designed and constructed for this study is described. The pressure drop characteristics of needle punched filters were investigated. The effects of flow rate, packing density, and needling intensity were studied. Experiments were also performed to determine the collection efficiency of needle punched filters using flyash. The effect of flyash concentration, time duration of test, and needling intensity were considered. The role played by the structure in utilizing the mechanisms of collection and reducing the time rate of pressure rise during filtration is discussed. A new scale for measuring the quality of performance of filters using dust and relating, in a dimensionless form, the dust penetration, the pressure drop, and the filter weight per unit area was also developed. Comparison between the performance of commercial woven and needle punched filters demonstrated the superiority of needle punched fabrics over woven fabrics in filtration.