Figure 2. SEM images of PPS-based bag filter materials with different
loading units (All the bars are 10μm).
failure sample (5#) than partly failure sample (3# and 4#), showing
that the cracks would extend with the increase of the content of
SO2.
In other words, the higher content of SO2 is, the larger
depth of cracks is, the deeper damage of the fiber is. Besides, the
service life of 5# is deeply destroyed below 200 MW is only 6 months,
while that of 1# and 2# is more than 20 months, indicating that the
structure transformation of fiber surface has nothing to do with the
service life in factories.
The same trend of structural evolution on fiber surface was observed
with the addition of SO2 content for samples loading
units between 200 and 300
MW
(sample 6#-10#) and above 300 MW (sample 11#-15#). This illustrates
that the loading unit of coal-fired power plants is independent of the
variation of fiber surface. It’s worth mentioning that the dust
particles are attached to the fiber surface for all samples. Commonly,
the dust particles would be removed from the network of bag filter by
the cleaning operation, and the fiber surface should be smooth in
accordance with the original morphology of PPS fibers. The appearance of
particles on the fiber surface indicates that the roughness of fibers
becomes obvious with the occurring of fiber degradation[9, 31], the
interaction between the fiber and particles increases with absorbance of
particles on the fiber surface, and thus above phenomenon can be
explained. The absorbance of particles around the fiber is larger for
sample 5#, 9#, 10# and 15#, whose SO2 content are
higher as 4000 mg/m3 than other samples, and this is
consistent with the degradation degree of PPS-fiber in the working
conditions. The higher the content of SO2 is, the larger
degradation degree is, the rougher of fiber surface is, and thus the
easier of particle adsorption becomes. Besides, the trapped particles
would increase the filtration resistance in the following cycling
process of dust removal, thus the performance of bag filters becomes
worse with the increase of SO2 content in the system.