Revisiting the Inhibition of Vanadium-Induced Hot Corrosion in Gas Turbines

Since the 1970s, nothing substantially new has been published in the gas turbine community about the hot corrosion by vanadium and its inhibition, after the “inhibition orthodoxy” based on the formation of magnesium vanadate, was established. However, the experience acquired since the late 1980s with heavy-duty gas turbines burning ash-forming fuels in southern China, shows that the combustion of very contaminated fuels does not entail corrosion nor abundant ash-deposit on gas turbines buckets. Analyses of deposits collected from gas turbines fired with these crude oils showed that the ash-deposit contains a large amount of nickel. These new facts led to revisit the role played by nickel and envisage its possible inhibiting action against the vanadium-induced hot corrosion. A thorough review of the literature on the vanadium-induced corrosion have been carried out, and the study of the nickel effects with respect to magnesium effects on the ash deposit have been performed. Results show that nickel presents an interesting way to substitute magnesium for the inhibition of vanadium-induced hot corrosion. The advantages of nickel with respect to magnesium are to be efficient at alow Ni/V ratio, to produce less abundant, less adherent ash and to act, to some extent, as a self-cleaning agent for the blades of the turbine.