4. Conclusions
The structural transformation and variation of mechanical properties of
PPS-based bag filter materials collected from the coal-fired power
plants with different loading units were investigated by SEM, FTIR and
TG.
As
the
SO2content increases in the flue gas, the oxidation degree of PPS fibers
becomes deeper accompanying with transformation from oxidation of C-S
bond to
sulfonation
of hydrogen in the benzene ring, and the surface evolution of above
fibers from smooth to cracked occurs at the same time. But the melting
point decreases with the addition of SO2 content, which
is in accordance with the changing of crystalline of PPS-based bag
filter materials. Thus, the reduction of crystalline and increasing of
surface defeats of PPS fibers brings down the CD strength of bag filter.
The major reason causing the failure of PPS-based bag filter is as
follows: working temperature (T) is often passing through acid dew gas
point (Ta), the SO3 would be produced
from condensing of H2SO4 when T is lower
than Ta. The SO3 with strong oxidation
would attack the weak bonds of PPS, resulting in the oxidation or even
sulfonation of PPS-based bag filters. Besides, the critical
concentration of SO2 in the flue gas is lower than 1500
mg/m3, which is beneficial for the safety and
long-time running of PPS-based bag filters in coal-fired power plants.
Supporting Information. Corresponding data summarized from FTIR
patterns are included in supporting information.