The influence of conditioning and regeneration on the separation behaviourof rigid surface filters for the separation of particles from gases

Rigid ceramic filter media can be used for the separation of particles from gas streams at elevated temperatures. In order to characterize comparative ly the separation behaviour of differently structured filter media over a m ultitude of filtration cycles, experiments were performed in a filter test rig. The filter test rig used is built in accordance with VDI guideline 392 6 and equipped with a special type of optical particle counter, which has t he advantage of measuring both the particle size and the particle concentra tion simultaneously and in situ on the clean gas side. It is demonstrated that by far largest share of the particles reaches the c lean gas as a result of the filter regeneration process. During the subsequ ent formation of the dust cake, the particle penetration is almost zero. Th e regeneration parameters, actually in essence only the tank pressure, poss ess the decisive influence on the separation behaviour. In the course of a filtration experiment, the number of particles reaching the clean gas reduc es with the increasing number of filtration cycles due to the filter condit ioning. The particles arriving in the clean gas during regeneration are ext remely fine. The mean particle size is almost entirely independent of the r egeneration conditions and the filter cycle number. The fine particulate em issions measured here are an anthropogenic source of particulate matter in ambient air. They have to be considered as relevant with respect to the new standards of ambient air quality (PM 10 and PM 2.5). It is shown that membrane-coated ceramic filter media at identical operatin g conditions exhibit, as expected, a better separation and regeneration beh aviour than fibrous ceramic, open-pored filter media. However, the advantag es are at the expense of a 10 times higher pressure loss, which is essentia lly attributed to the membrane layer. (C) 2001 Elsevier Science B.V. All ri ghts reserved.