Corrosion monitoring of Type 304 Stainless Steel in a Black Liquor Evaporation Process

摘要

A corrosion monitoring probe was designed and tested in situ under conditions pertinent to the black liquor evaporation process in a pulp and paper plant. Overall, the corrosion rates recorded for Effect 2 were higher than those measured on Effects 3 and 6. It is thought that this behavior could be greatly influenced by the temperature conditions and changes in the composition of the black liquors on each effect during the various periods of monitoring. For a given effect, the trends in corrosion rates measured by Tafel extrapolation and LPR were similar. The numeric corrosion rate values found by Tafel extrapolation were about twice those found by LPR. This is attributed to the anodic and cathodic reactions that may be occurring in each liquor, which the measurement techniques may not indicate.