Water-Based Yttrium Additive for Hot Corrosion Inhibition in a Gas Turbine

Abstract

Abstract Hot corrosion is a major problem for operating gas turbines running on vanadium-laden liquid fuels. Upon combustion, vanadium combines with oxygen forming vanadium pentoxide (V2O5) which is highly corrosive and has a melting point below the hot gas path (HGP) operating temperature. This causes V2O5 to melt down and attack the HGP parts in what is known as hot corrosion. To mitigate the potential for hot corrosion of vanadium on gas turbine parts, a corrosion inhibitor is typically injected with the fuel. The role of the corrosion inhibitor is to chemically react with V2O5 to form non-corrosive chemical molecules, which appear as “ash”. Magnesium-based inhibitors are commonly used in gas turbine applications. However, a high volume of ash accumulates on turbine blades causing degradation of the turbine performance. A promising alterative, which is a yttrium-based inhibitor, was tested and compared with magnesium-based inhibitor in this investigation. Laboratory-scale testing of ash formation and corrosion inhibition were conducted for both inhibitors. The results proved that yttrium inhibitor achieved superior performance in comparison to magnesium inhibitor in terms of less ash formation and higher hot corrosion resistance. Furthermore, both inhibitors were tested in an E-class gas turbine pilot test. The acquired performance data confirmed the superiority of yttrium as an inhibitor in comparison to magnesium.