Settling Aids

Metals, ash, and solid contaminants

Residual and distillate-based marine fuels often contain catalytically cracked blend components such as FCCU slurry oil that are great blend components, especially for lower sulfur fuels such as VLSFO. While slurry oil and other cracked materials are high in energy content & low in sulfur, they contain various metals and inorganic solids such as catalyst fines that get carried over from the processing unit.

For example, fluid catalytic cracking units (FCCU) use catalyst that are comprised of aluminum (Al) and silicate (Si). During the process, small amounts of these metallic particles are lost to the slurry oil being produced. In addition, the feedstock to these and other cracking units can contain trace levels of other metals such as iron, vanadium, nickel and sodium that can also get carried over into fuel oil blend streams during processing.

These solids result in ash formation, contribute to filter plugging, cause erosion/abrasion wear inside onboard fuel systems, and they can foul ship engines resulting in poor combustion, increased emissions, and poor fuel economy. Therefore, to ensure good operability, it is important to limit the level of solids present in fuels. The ISO 8217 fuel standard for marine fuels has maximum allowable concentration limits for ash and for metals.

It is preferable to remove solids as early in the blend process as possible. Centrifugation and filtration are possible mechanical solutions. However, these mechanical solutions are often not practical in the field. Storing contaminated blend streams or finished fuels and allowing the solids to gravity settle over time is another possible field solution. However, the settling time required to reach acceptable limits is often not operationally or economically viable. Use of an Innospec Trident solids settling aid can greatly improve the efficiency of solids removal.

Innospec offers a variety of settling aids to meet the demands of the ever-changing bunker fuel market. Please contact your Innospec representative to discuss how we can custom tailor a solution for your needs.

Innospec’s Trident™ 400 Solids Settling Aid
A cost-effective alternative solution to help removing existing solids is to add the Trident 400 Solids Settling Aid from Innospec to contaminated fuels and fuel streams ahead of tankage.

Trident 400 enhances the coagulation and flocculation of solids which reduces the time needed for settling and removal. Trident 400 can also be used in combination with mechanical separators (e.g., centrifuges, purifiers) to improve their separation efficiency.


  • Accelerates the settling of solids in slurry oil during storage
  • Improves the efficacy of solids removal during mechanical separation
  • Improves system throughput by reducing filter plugging
  • Reduces the wear and erosion of fuel system components
  • Improves operability by reducing engine system fouling
  • Increases the value of hydrocarbon streams containing catalyst fines or metals