Pulse-jet regeneration of surface filters at low absolute pressures

Pulse-jet cleaning of surface filters at reduced absolute pressure is not yet well quantified. This work investigates pulse-jet regeneration at p$_{abs}$=900, 100, 25, and 10 hPa using a flexible spunbond (SB) medium and a rigid sintered granular medium (SG). Regeneration pulses were first characterized on clean media while varying valve opening time, tank pressure, absolute pressure and filter face velocity. The valve opening time primarily controlled pulse duration, whereas variation of tank pressure mainly affected the maximum differential pressure. At constant tank pressure and valve opening time, decreasing absolute pressure increased the maximum differential pressure and delayed the occurrence of this maximum. For comparable cleaning strengths across all absolute pressures, tank pressure was adjusted at each absolute pressure to approach a predefined target value of the maximum differential pressure. Filter cakes were formed using Mikhart MU 08 at similar mass loadings of approximately 50 g m$^{-2}$. High-speed imaging synchronized with the differential pressure signal reveals distinct medium dependent detachment dynamics. For SB, cake detachment starts close to flow reversal, whereas for SG detachment is delayed. ... mehrReduced absolute pressure shifts the timing and prolongs the duration of the cake detachment phase. Cleaning efficiencies decrease with decreasing absolute pressure for comparable pulse strengths, with a stronger sensitivity for SG than for SB.