Relationship between particle charge and electrostatic enhancement of filter performance

Abstract

As an important particle collection method, filtration is significantly affected by particle precharging. The filtration of differently charged fly ash particles using membrane and fibrous filters was experimentally studied. Particle charge was directly measured and quantitatively related to the enhancement of filter performance. Particle penetration, which was observed in the fibrous filter during the early stages of filtration, exponentially decreased with increasing particle charge when the filter was clean and rapidly decreased with increasing particle load. A penetration reduction factor ψ was defined to represent the effect of particle charge on penetration, and its correlation with particle charge was defined on the basis of the fitting experimental results. The average porosity of the dust cakes that were formed on both filters increased with particle charge, which in turn exponentially decreased the pressure drop. The electrostatic effect on pressure drop was less prominent than that on penetration. A pressure drop reduction factor θ was defined to quantify the effect of particle charge on pressure drop. Correlations for predicting the evolution of average cake porosity and pressure drop in consideration of particle charge were proposed on the basis of the fitting experimental results.