Massive Recirculation as a Method of Minimizing Corrosion in the Combustion of Residual Fuels

Metal surfaces exposed to combustion gases from residual fuels suffer from fouling and severe corrosion. Several methods currently in use to combat these effects include chemical treatment of the fuel, combustion at near stoichiometric conditions, and the use of protective coatings. This study introduces another method based primarily on improved burner technology, specifically, combustion with massive, external recirculation. Short (10-hr) and long (30-hr) exposure time tests have demonstrated that the combustion of untreated oil having a high vanadium and sodium content with sufficiently large recirculation produces corrosion of essentially the same magnitude as that experienced from the combustion of diesel fuel without recirculation. These beneficial effects of recirculation are greatest at conditions giving rise to highest corrosion rates, i.e., at high excess air and high metal temperature.