Performance of fuel oil additives on simulated superheater surfaces; part 2: mechanisms of additive action

Magnesium and manganese additives were investigated in a laboratory combustor using a high-sulfur, high-vanadium residual oil. Ash deposits were collected on simulated superheater surfaces at 1100 F. Scanning electron microscope, x-ray diffraction, and energy dispersive x-ray analysis of the deposits showed that the first MgO reaction is formation of MgSO/sub 4/, followed by formation of magnesium vanadates. Previously unreported phases containing magnesium or manganese with both sulfur and vanadium were detected in the deposits. Utility boiler deposits were compared with those formed in the laboratory combustor.