3. Results and discussion
3.1 Morphologies of PPS-based bag filter materials
SEM images of PPS-based bag filter materials collecting from coal-fired power plants with different loading units were shown in Fig. 1. A three-dimensional interpenetrated configuration is easily observed for all samples regardless of loading units of coal-fired power plants, which is built by stacking of PPS fibers through nonwoven technology to furnish the bag filter with open-cells pores and high porosity. The existence of above network makes it possible to filter dust particles effectively for PPS-based bag filters with excellent dust rejection rate.
When the loading units is below 200 MW (sample 1#-5#), the relatively smooth surface along the fiber axis accompanying with little particles is observed for sample 1# and 2#. While the regular cracks liking knife cuts that vertical to the fiber axis appear for sample 3#, 4# and 5#. From Table 1, the status of bag filters changes from using to complete failure for sample 1#-5#, indicating that the evolution of surface of PPS-based bag filter materials from smooth to cracked occurs as failure degree increases, which is in line with the content variation of SO2 in the system and would be discussed in detailed in section 3.4. The depth of cracks becomes more intensified for completely