A pilot plant study of the effect of alkali salts on initial stages of the high temperature corrosion of alloy 304L
Journal article, 2004

Alloy 304L was exposed for between 15 min to 12 hr in the 12MW CFB research boiler at the Chalmers university of technology using an air-cooled probe. The base fuel consisted of a mixture of 67% wood chips and 33% pellets. In addition to the base fuel experiment, a number of exposures were performed where S and Cl was added to the fuel in the form Of SO2(g) and HCl(aq) in order to control the flue gas chemistry in the superheater region. After the exposures the samples were analysed by ESEM/EDX, XRD and SAM. Burning a mixture of woodchips/pellets without adding sulphur or chlorine results in the formation of K2SO4 deposits on the corrosion probes. When HCl is added to the fuel KCl deposits form. The simultaneous addition of HCl and SO, results in a deposit consisting of a mixture of KCl and K2SO4. In all environments studied an oxide in the 100nm range forms. With time, the oxide becomes covered by ash deposits. After exposure to the biomass flue gas environment, the oxide is enriched in K, especially the outer part. Chlorine is not present in the oxide even when the KCl(s) forms on the surface. It is suggested that potassium chromate formation occurs by the reaction of potassium chloride with chromium oxide.

Author

Jesper Pettersson

Chalmers, Department of Environmental Inorganic Chemistry

Carolina Pettersson

Chalmers, Department of Environmental Inorganic Chemistry

Henrik Asteman

Chalmers, Department of Environmental Inorganic Chemistry

Jan-Erik Svensson

Chalmers, Department of Environmental Inorganic Chemistry

Lars-Gunnar Johansson

Chalmers, Department of Environmental Inorganic Chemistry

Materials Science Forum

0255-5476 (ISSN)

Vol. 461-464 965-972

Subject Categories

Materials Engineering

Chemical Sciences

More information

Latest update

10/15/2018