Challenges in Modern Fuel Oil Quality
Refinery operations increasingly incorporate cracked streams, from FCC, visbreaking, and thermal cracking, into middle distillate and fuel oil pools. These streams are economically attractive but introduce instability: higher olefin content accelerates oxidation and gum formation, and asphaltene-containing residual blends are susceptible to precipitation and sedimentation, particularly when blends from different crude sources are combined.
In marine applications, IMO 2020’s 0.5% sulfur cap drove a rapid shift to Very Low Sulfur Fuel Oils (VLSFO). These blends, assembled from diverse refinery streams, present new compatibility challenges. Incompatible components cause asphaltene flocculation, tank sedimentation, and filter plugging, with serious operational consequences at sea where maintenance options are limited.
Refinery application: Fuel oil additives (FOA) allow refiners to improve blend economics, increasing the proportion of lower-cost cracked streams in the finished distillate pool while maintaining oxidation stability and specification compliance (e.g., IP 391 oxidation test, sediment by hot filtration).
Key Functions
Combustion Improvers
Catalytic combustion additives (organometallic iron or manganese compounds) lower the ignition temperature of fuel oil, improving burn efficiency, reducing soot and particulate in exhaust, and preventing furnace and boiler fouling from carbonaceous deposits.
Asphaltene Dispersants
Polymeric dispersants adsorb onto asphaltene particle surfaces, preventing agglomeration and sedimentation in blended VLSFO, HFO settling tanks, and centrifuge systems, critical for marine operations post-IMO 2020.
Sludge and Deposit Control
Detergent additives prevent carbonaceous and varnish deposits on burner nozzles, boiler tubes, and heat exchange surfaces, maintaining heat transfer efficiency and reducing descaling frequency in industrial and marine boilers.
Cracked Stream Stabilizers
Antioxidant packages formulated specifically for olefinic FCC naphtha and light cycle oil streams, extending induction periods and preventing gum formation during blending, storage, and transit.
Marine Fuel Context (IMO 2020+)
VLSFO blends sourced from different refineries vary widely in composition, some paraffinic, some aromatic, and incompatible fuels commingled in bunker tanks during bunkering can cause rapid asphaltene precipitation. Stability additives dosed at the bunkering point or in the storage tank protect against operational failure at sea. A simple ASTM D7112 spot test or P-value measurement can indicate compatibility risk before blending.