According to the analysis of the corrosion results of the PPS filter bag, there are three main sources of corrosion: oxidation, sulfur trioxide and nitrogen dioxide.
1. S—H2SO4
S in the flue gas forms SO2 and then becomes SO3 by oxidation. In the presence of water vapor, sulfurous acid vapor and sulfuric acid vapor or aerosol will be formed and condensed on the PPS filter bag to form dilute sulfurous acid and dilute sulfuric acid. With the passage of filtration time and the increase of temperature, the water in dilute sulfurous acid and dilute sulfuric acid is volatilized and gradually converted into concentrated sulfuric acid with strong oxidizing property, which oxidizes and corrodes the PPS filter bag and makes the PPS filter bag ineffective.
2. NO2
Strong oxidants can directly oxidize and corrode the PPS polymer chain, resulting in chain scission of the PPS polymer chain. In the presence of water vapor, nitric acid vapor will be formed to condense and oxidize PPS on the filter bag, and at the same time, in the presence of concentrated sulfuric acid and a catalyst, a nitrification reaction will occur.
3. O3
Strong oxidizing property, it can directly oxidize and corrode PPS, resulting in a sharp decrease in the strength of the fiber filter bag. At the same time, O3 also has the ability of desulfurization to remove S in the PPS molecule.
