Corrosion engineer, Pacific Gas and Electric Co., San Ramon, CA
Pages: 21 Published: Jan 1987
Corrosion and erosion in the limestone slurry scrubber module is described. An electrochemical technique of the two-electrode system was used to determine the corrosion rates. The results were compared with the weight-loss method. The tendency of carbon and stainless steels to pit was also determined. Pitting was expressed as the “pitting factor.”
Materials and coating problems were found to vary considerably inside the module depending on location, amount of deposits on surfaces, type of protective coating, and care in surface preparation. Because of deposits formation, the application of the two-electrode polarization instrument method has to be carefully considered for continuous corrosion measurements in erosive-scaling liquids such as the scrubber spray slurry. Application of the “pitting factor” was useful to assess the penetration increase when erosion-corrosion took place. Monolithic linings, reinforced with glass mat, cloth, or flake showed the best erosion resistance. The quality of surface preparation was essential to lining life. It was found, however, that after ten years of scrubber, 25% of the original area of the scrubber coatings was replaced by clad Type 304 stainless steel.
scrubber, limestone slurry, corrosivity, erosion, polarization, two-electrode system, corrosion rate, pitting factor, kinetics, corrosion-erosion protection, thermosetting resins, polyester, failure
Paper ID: STP19421S