Heavy Fuel Oil Additives

Heavy fuel oils carry vanadium, sodium, and sulfur. During combustion these form low-melting ash and sulfur trioxide (SO₃), leading to slagging on superheaters, high-temperature corrosion, and acid dew-point attack in cold-end equipment. Fuel additives modify the ash chemistry so deposits stay dry and removable and these corrosion mechanisms are suppressed.

Oil-soluble magnesium reacts in the flame with vanadium compounds to form magnesium vanadates that melt well above fireside metal temperatures, so ash stays friable instead of fusing to tubes. Magnesium oxide also neutralizes part of the SO₃, reducing sulfuric acid condensation in cold-end equipment and visible stack plume.

Start from a fuel analysis — vanadium, sodium, and sulfur content — plus your firing rate and dosing equipment. Higher-vanadium fuels or sites wanting minimal feed volume favor a higher-concentration grade such as CHIMI MAG 30; units with lighter requirements often run the 20% grade. CHIMI ART's technical team recommends a grade and starting ratio from your data.

They are metered continuously into the fuel line ahead of the burner, proportioned to fuel flow. Effectiveness is tracked through fireside inspections during outages, ash appearance and analysis, stack plume observation, and boiler heat-rate trends, with the additive-to-fuel ratio adjusted accordingly.