Corrosion Studies on Structural Alloys for Flue-Gas Desulfurization Systems

摘要

Several Mo- and Cr-bearing structural alloys of potential applicability in downstream regions of flue-gas desulfurization (FGD) systems have been examined for corrosion in simulated FGD environments at 85 exp 0 C. To evaluate the importance of hydrogen and chloride ion concentrations, Type 316L stainless steel was exposed for varying times at different pH levels (0.5 to 3.0) and chloride content (0.03 to 5.0 wt % Cl exp - ). To determine the effects of pH and alloy composition in acid solution that contains a fixed amount of chloride (approx. 0.34 wt % Cl exp - ), a number of alloys were used in which the composition parameter (defined as the sum of Cr and Mo) varied from 19.5 to 33.5 wt %. In all cases, the general corrosion or dissolution as determined from weight loss measurements varied linearly with time. The corrosion rate for the alloys decreased with an increase in pH in a consistent manner regardless of the alloy crystal structure. The composition effects on corrosion rate were most significant at pH = 0.5. The dependence of corrosion rate on pH, chloride ion concentration, and alloy composition is presented in a quantitative manner and the technical as well as technological importance of these results is discussed. 9 figures, 2 tables. (ERA citation 08:028863)