CFD analysis and parameter optimization of explosion suppression powder injection in a bag filter

The accumulation of combustible dust in industrial bag filters poses severe explosion risks. Automatic suppressant powder injection serves as a key protective measure, whose effectiveness hinges critically on the injection flow field and the uniformity of suppressant dispersion. This study employs a transient gas-solid two-phase CFD model in ANSYS Fluent to investigate an industrial bag filter. Based on the Euler-Lagrange framework and the Discrete Phase Model (DPM), flow field characteristics and suppressant dispersion patterns were systematically analyzed under three injection directions (downwind, upwind, sideward) and two pressures (4 MPa and 5 MPa). The coefficient of variation (COV) was introduced to quantify distribution uniformity. Results indicate that the downwind injection at 5 MPa achieves an optimal balance between coverage and stability, yielding a bottom average dust concentration of 0.85 kg/m 3 and a COV of 0.33. The sideward injection at 4 MPa offers better flow stability (COV = 0.42) albeit with slightly lower coverage. In contrast, the upwind 5 MPa condition is the least favorable, as intense vortices induce suppressant re-suspension. These findings provide a theoretical basis and direct parametric guidance for the explosion-proof design and optimization of bag filter systems. • CFD analysis reveals the coupled effects of injection direction and pressure on explosion suppression flow fields. • Downwind injection at 5 MPa provides optimal coverage and stability, while upwind injection causes powder re-suspension. • The coefficient of variation is introduced to quantitatively evaluate the uniformity of powder dispersion. • Hopper bottom flow activity is identified as a key indicator of explosion suppression effectiveness. • Engineering guidelines are proposed for optimizing explosion protection in industrial bag filters.