Experimental study of pulse-jet cleaning of bag filters supported by rigid rings

Abstract

This study embodies experimental characterisation of pulse-jet cleaning of filter bags supported by rigid rings. Tests were conducted on a semi-industrial pilot dust collector. Signals were monitored along bag filters (over their full height) to provide a record of key parameters: pressure drop, filter medium acceleration, face air velocity and axial velocity of the compressed air jet. These measurements provided a description of filter medium behaviour during cleaning. It was found that a number of mechanisms cause dust cake dislodgement. Sudden movement of the medium, recorded over the full height of the filter element, is linked to intense shaking of the medium at the top of the bag and strong permeation of reverse airflow through the fabric at the bottom of the bag. The top and bottom sections represent the bag areas in which regeneration is most efficient. Filter medium properties changes, following gradual internal clogging, modify extensively the reaction of the bag during pulse-jet cleaning. A further innovative aspect of this experimental study is that impacts of main cleaning parameter and filtration operating condition were investigated using the same test equipment. The number of results represents a significant contribution to understanding pulse-jet cleaning phenomena. This study highlights a potentially increasing factor involving downstream particle emission. This entails significant aspiration of dirty air near the top of the bag during pulse-jet cleaning, when the compressed air injection nozzle is too close to the mouth of the filter element.