Effect of relative humidity and dust moisture content on filtration performance of bag filter

Abstract

Bag filters are commonly used to remove fine particulate matter from industrial flue gases. Rapid formation of dense dust cakes is a major issue in bag filters as it necessitates more frequent cleaning, leading to higher operating costs. The rate of cake resistance formation is related to the interparticle forces, which vary with the wetting state of the particle surface. To reduce the cake resistance, moisture is introduced via two methods: regulating the ambient relative humidity (RH) and dust moisture content. The results show that the introduction of moisture affects the cake thickness, mass loading, and particle size distribution on the filter bag, which are critical factors in determining cake resistance. Higher RH and conditions far from the critical dust moisture content (1.44%) contribute to low-resistance filter cakes. In addition, a non-uniform filter cake structure on the surface of the filter bag was investigated, and a correlation between the filter bag height and the filter cake structure parameters was developed. We introduced interparticle forces into computational fluid dynamics coupled with discrete phase model (CFD-DPM) simulations to simulate the wet particles. Particle agglomerates and flow field forces are attributed to the non-uniform particle distributions on the filter bag. These findings provide insights into reducing cake resistance and routes to control increasing resistance over time, as well as a more accurate prediction of cake resistance.