Patchy cleaning of rigid gas filters—transient regeneration phenomena comparison of modelling to experiment

Rigid ceramic filter media, widely used for the removal of particles from gas streams at elevated temperatures tend to show patchy cleaning when the filter regeneration is incomplete [Filtr. Sep. (1989) 187]. In order to investigate the regeneration behaviour and the operational performance of partially regenerated, rigid gas cleaning filter media over many filtration cycles, experiments were performed in a filter test rig. The regeneration behaviour of the filter sample was characterized by the overall regeneration efficiency, the local frequency of regeneration, and the number and size of regenerated filter areas. Using only four adjustable parameters, our modelling results compare favourably with our experimental results, at room temperature. This favourable comparison of the regeneration behaviour between modelling and experiment is achieved only if it is assumed that cohesive and adhesive bonds, which are broken during filter regeneration, do not heal during the next filtration cycle. Assuming otherwise would cause (i) the dust cake to be removed at the same positions during every regeneration and (ii) the patch size to increase from cycle to cycle instead of decreasing as seen in the experiment. Therefore, the model development was guided by our extensive experimental results. This agreement of modelling with experiment indicates that the modelling has real predictive capabilities for operational filter cleaning. Both filter conditioning and dust cake compression significantly influence the operational performance of partially regenerated filter media.