Compressional behavior and filtration performance of coalescing fibrous media

Abstract

Fibrous materials are subjected to compression in many industrial processes, such as natural gas filtration at high pressures. A number of investigations have been conducted to study the relationship among compression load, pore size and permeability. However, the effect of structural parameters on the filtration performance of compressed media has not been reported. In our study, the variation of packing density, pore size distribution and contact angle for both oleophilic and oleophobic glass fibrous materials with different degrees of compression were experimentally measured. Furthermore, the filtration performance of compressed filters such as wet pressure drop, penetration, saturation, and liquid distribution are investigated. The results showed that the contact angle of the filter material did not change within the compression range of 55%, but the liquid holding capacity was improved, which was due to the increase of fiber surface area per unit volume with the increase of compression amount. After compression, the pore size distribution shifted to small pores, leading to an increase in jump pressure drop. For multi-layer filters, the channel pressure drop was affected by the variations of the thickness, packing density and pore size of filter material. In addition, the saturation depended on the interaction between the fiber surface area per unit volume and the interstitial velocity, which also determined the liquid distribution in the filter. And for single-layer filters, the diffusion mechanism was weakened after compression, resulting in an increase in the penetration for droplets smaller than 500 nm.