Downstream particle puffs emitted during pulse-jet cleaning of a baghouse wood dust collector: Influence of operating conditions and filter surface treatment

Baghouse dust collectors are widely used to removewood particles fromdust-laden air before it is expelled from or recycled intoworkplaces. Despite the growing use of filter media with supplementary surface treatment, conventional open-faced filter media or other common media are still widely used in the woodworking industry. More efficient filter media may help to reduce downstreamparticle emission. This article describes the emission performances of two polyester fiber filter media: one with a smooth anti-adhesive thermo-bonded surface, and the second covered with a microporous polymeric membrane. For the two media, 250 filtration cycles were performed on a 24-bag pulse-jet cleaned pilot dust collector loadedwith coarsewood dust from a joinery workshop. Emitted particle concentrations and downstream particle size distributionswere measured for various operating conditions. The data presented focus on particle puffs emitted during pulse-jet cleaning as this is known to be the
most problematic stage. For both media, our results confirm the prevailing opinion that higher pulse-jet cleaning intensities increase particle emission, however this also reduces regeneration frequency. Increasing the maximum pressure drop across the filter bags before regeneration leads to higher average downstream mass concentrations during pulse-jet cleaning. The wood particles emitted during puffs are predominantly sub-micronic. For all operating conditions, the medium with a polymeric membrane was associated with lower particle emissions than the more commonly used thermo-bonded medium. However, during pulse-jet cleaning, neither of the media tested provided a mass concentration below 0.2 mg·m3, the recommended concentration value for air recycling in France.