Influence of the deliquescence and efflorescence of hygroscopic salt particles on the performance of surface filters

D. Horst*, Q. Zhang, E. Schmidt, University of Wuppertal, Germany

The progress of pressure loss during the filtration phase as well as the residual pressure loss after regeneration are characteristics of the performance of surface filters for dust separation. These characteristics are significantly influenced by both the specific cake resistance and the adhesive forces of dust particle contacts. The specific cake resistance decreases, besides other factors, with increasing pore sizes. The mechanical strength of the dust cake in turn depends on the adhesive forces of particle contacts in the dust cake. For the removal of the dust cake from the filter medium an increased mechanical strength is desirable, since the amount of energy needed for regeneration can be reduced. In terms of process technology, these characteristics can be influenced by raw gas conditioning, for example by changing the particle characteristics in the dust cake.

The metered addition of a fraction of hygroscopic salt particles provides a possibility for influencing the performance of surface filters for dust separation. By temporary modification of the gas humidity deliquescence and efflorescence of the added salt particles will be induced to subsequently change the adhesive forces of particle contacts as well as the structure of the dust cake formed on the filter medium. This changes the performance of the filter.

The present contribution presents investigations into the influence of the change in the performance of test filters by inducing deliquescence and efflorescence of a fraction of salt particles in a dust cake. These investigations were carried out on an adapted filter test apparatus according to VDI 3926-1. The conditioning concept as well as the operating behavior of test filters, such as the pressure loss curves and the regeneration results are presented.

Session: G8 - Short Oral Presentations
Day: 23 October 2019
Time: 14:45 - 16:00 h

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