Correlation between sodium sulfate mass transfer and low-temperature hot corrosion

Abstract

A mass transfer model is developed that considers diffusive and chemical aspects of sodium sulfate formation and deposition on cooled blades of coalfired gas turbines. The roles of gas phase condensation of sodium sulfate and multicomponent diffusion across a chemically frozen thin boundary layer are elaborated. A rational procedure is presented for correlating material wastage with laboratory weight gain data obtained by exposing alloy specimens precoated with a thin film of salt to S0 2 -SO 3 in an oxygen environment. The sodium sulfate mass transfer model is used in conjunction with the correlation to project blade corrosion and lifetime as a function of gas turbine inlet temperature, blade cooling, and sodium and sulfur contaminant concentration.