Figure 5. The variations of CD strength of PPS-based bag filter materials with different loading units.
According to the GB/T 6719, the CD strength of filter bags should more than or equal to 1200 N, while the CD strengths of all samples except 6# are lower than that value indicating that all samples are subject to degradation under the complicated and corrosive atmospheres. CD strength decreases for three categories (below 200 MW, 200-300MW and above 300 MW) as the content of SO2 increases independence of loading unit. Commonly, the tensile strength of bag filter is closely related to the crystallinity and defeats of PPS fiber adopted[35]. The tensile strength becomes larger with the increase of crystalline of PPS fiber, while declines with the addition of defeats which would turn into stress concentration points to accelerate the fracture of fiber. From the above analysis, the crystalline reduces and surface defeats of PPS fibers rises with the content of SO2 increases, bringing down the CD strength of bag filter at the same time. Besides, it’s worthwhile to notice that the CD strength of samples is lower than 600 N that nearly 50% loss of theoretically initial strength when the content of SO2is more than 1500 mg/m3, which can’t afford the normal run of dedusting and cleaning resulting in the failure of bag filter.
3.4 Mechanisms of structure evolutions of PPS-based bag filter materials
The evolutions of structure and mechanical property of PPS-based bag filter materials with different loading units were clarified in detail, but the dominating factor bringing about above variations is unclear and needs to be further explained.