Application of Cathodic Protection on Metallic Structure in Extremely Acidic Fluids

  • Chang, H.Y. (Korea Power Engineering Company Inc.) ;
  • Yoo, Y.R. (School of Advanced Materials Engineering, Andong National University) ;
  • Jin, T.E. (Korea Power Engineering Company Inc.) ;
  • Kim, Y.S. (School of Advanced Materials Engineering, Andong National University)
  • Published : 2005.08.01

Abstract

Fossil fired power plant produces the electric energy by using a thermal energy by the combustion of fossil fuels as like oil, gas and coal. The exhausted flue gas by the combustion of oil etc. contains usually many contaminated species, and especially sulfur-content has been controlled strictly and then FGD (Flue Gas Desulfurization) facility should be installed in every fossil fired power plant. To minimize the content of contaminations in final exhaust gas, high corrosive environment including sulfuric acid (it was formed during the process which $SO_2$ gas combined with $Mg(OH)_2$ solution) can be formed in cooling zone of FGD facility and severe corrosion damage is reported in this zone. These conditions are formed when duct materials are immersed in fluid that flows on the duct floors or when exhausted gas is condensed into thin layered medium and contacts with materials of the duct walls and roofs. These environments make troublesome corrosion and air pollution problems that are occurred from the leakage of those ducts. The frequent shut down and repairing works of the FGD systems also demand costs and low efficiencies of those facilities. In general, high corrosion resistant materials have been used to solve this problem. However, corrosion problems have severely occurred in a cooling zone even though high corrosion resistant materials were used. In this work, a new technology has been proposed to solve the corrosion problem in the cooling zone of FGD facility. This electrochemical protection system contains cathodic protection method and protection by coating film, and remote monitoring-control system.

Keywords

References

  1. H.Y. Chang and G. Hwangbo, 'The application of EP system for FGD in power stations', Interim report, KOPEC (2002)
  2. Y. S. Kim, Metals and Materials, 4, 183 (1998)
  3. J. Charles, 'The duplex stainless steels', Duplex Stainless Steels '91, p.3-48 (1991)
  4. J. O Nilsson, Material Science and Technology, 8, 685 (1992)
  5. Y. S. Kim, Y. S. Park, B. Mitton, and R. Latanision, 'The role of nitrogen and molybdenum in the corrosion of stainless steels', Proceedings of the symposium on critical factors in localized corrosion III, eds. R. G. Kelly, G. S. Frankel, P. M. Natishan, and R. C. Newman, p.89, The Electrochemical Society, Inc., (1999)
  6. Y. S. Kim and H. Y. Jang, 'The influence of W and Mo addition on the passivity of stainless steels', Passivity and localized corrosion, eds. M. Seo, B. MacDougall, H. Takahashi, R. G. Kelly, p.513, The Electrochemical Society, Inc., (1999)
  7. Y. S. Kim and Y. S. Park, 'Super stainless steels for nuclear power plants', Proceedings of the symposium on nuclear materials and fuel 2000, The Korean Institute of Metals and Materials, p.605, Taejon, August 24-25, (2000)
  8. Y. S. Kim, H. Y. Chang, G. Hwangbo, and S. H. Hong, Localized corrosion resistance of high N and high chromium bearing stainless steels', 2001 MRS Spring Meeting, April 16-20, San Francisco, USA, (2001)
  9. ASTM, 'Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use Ferric Chloride Solution', ASTM G48-92, Method A
  10. ASTM, 'Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use Ferric Chloride Solution', ASTM G48-00, Method C
  11. A. Garner, Corrosion, 37, 178 (1981)
  12. H. Heuber and M. Rockel, Werkstoffe und Korrosion, 37, 7 (1986)
  13. Y. S. Kim and Y. S. Park, Corrosion Science and Technology, 18, 67 (1989)
  14. H. Y. Chang, S. H. Hong, and Y. S. Kim, Corrosion Science and Technology, 31, 70 (2002)