Permeability of filter cartridges used for natural gas filtration at high pressure

The permeability of cylindrical filter cartridges commonly used for natural gas filtration was investigated in this reported work. Sample cartridges were composed of polyester, polypropylene, polyamide and three types of glass fiber with different fiber diameters. The pressure drop and permeability coefficients of the filters were measured at absolute pressure 0.1 MPa and 11 MPa, with a face velocity up to 0.25 m/s. At 0.1 MPa, the resulting permeability coefficients k1 (1.08-40.68 × 10−12 m2) and k2 (0.74-1.04 × 10−7 m) were typical of the fiber media used in filtration applications. The parameter k1 was accurately predicted using the Kuwabara model with a packing density in the range 0.05 < α < 0.30. At 11 MPa, k1 (0.72-2.29 × 10−12 m2) and k2 (0.23-0.37 × 10−7 m) were significantly lower than at atmospheric pressure. The filter materials experienced a significant change when used in the field. After high-pressure test, the average pore diameter of glass fiber increased and the thickness of needled felt decreased greatly, while the fiber diameter experienced little change in all of the filter cartridges. The permeability coefficients decreased at high pressure. Therefore, the change in the permeability coefficients of the filter should be considered when predicting the pressure drop of the filter cartridges at high pressure. Filter designers can use the data presented in this study to select filter materials based on the variations in permeability coefficients.