Dust cake build-up on gas cleaning surface filters at ambient and low absolute pressure

The design of surface filtration systems operating at low absolute pressure remains underexplored, due to the lack of detailed studies on filter cake formation at such conditions. This study investigates both formation and flow resistance of filter cakes at varying absolute pressures after characterization of aerosol properties in the feed flow at reduced pressures. At constant operating conditions at the dosing unit, the particle number concentration decreases with decreasing absolute pressure due to gas expansion and dilution effects. In contrast, the number based particle size distribution remains largely unaffected across the investigated pressure range. At these conditions, filter cake formation at very low absolute pressures is significantly more time-consuming than at ambient conditions, two methods for cake formation were compared at constant filter face velocity: (A) cake formation and pressure drop measurement at the target system pressure and (B) cake formation at normal temperature and pressure followed by stepwise system pressure reduction and subsequent pressure drop measurement at a fixed flow velocity. The resulting cake resistances were compared using a specific filter cake constant C F C . The comparison revealed good agreement between both methods at each absolute pressure level, indicating that no structural changes occur in the filter cake due to absolute pressure variation. These findings demonstrate that method B is a valid approach to substantially reduce experimental time while maintaining structural comparability of the filter cakes. The results contribute to a deeper understanding of filtration behavior at vacuum conditions and provide a methodological basis for future investigations and process development in low pressure filtration systems. • First dataset on surface filter cake structure and resistance at low pressure. • Establish pressure consistent aerosol conditions from 900–10 mbar for comparisons. • Compare two methods for cake build-up: low pressure vs ambient. • Demonstrate a rapid, reproducible approach for efficient low pressure studies. • Cakes formed at ambient pressure show no structural change after pressure reduction.