FACTORS INFLUENCING PRESSURE-DROP THROUGH A DUST CAKE DURING FILTRATION

Three kinds of dust materials, fly ash (MMAD : 6.28 mu m), limestone ( MMAD:2.53 mu m) and SAE fine dust (MMAD : 3.88 mu m), have been used t o test the dust cake compaction and its influence on the specific dust cake resistance coefficient at filtration velocity ranging from 1 to 9 cm/sec. An accurate laser dispacement system was used to determine d ust cake thickness and the amount of dust cake compaction during filtr ation. In the range of filtration velocity tested, dust cake compactio n has been found to occur. Higher filtration velocity results in large r amount of irreversible dust cake compaction acid lesser amount of el astic dust cake compaction. The experimental specific dust cake resist ance coefficient, K-2, has also been found to increase with an increas ing filtration velocity. For the three dusts tested, K-2 relates to fi ltration velocity V-f as K-2 proportional to V-f(n), where n is 0.52, 0.38 and 0.43, for fly ash, limestone and SAE fine dust respectively. The theoretical K-2 values predicted by the Rudnick-Happel equation ha s been shown to agree better with the experimental K-2 values than tho se by the Kozeny-Carman equation. The maximum difference between the K -2 values predicted by the Rudnick-Happel equation and the experimenta l values is less than about 16%. (C) 1998 American Association for Aer osol Research.