Marine fuels sludge management

Before 2020, most vessels were using Heavy Fuel Oil, colloquially known as HFO.

HFO, derived as a residue from crude oil distillation, has a high sulphur content of up to 3.5%. HFO is viscous and highly aromatic, containing high levels of asphaltenes, typically between 3 and 18%.

Asphaltenes are large polar, polyaromatic molecules, which will precipitate upon changes in thermal, pressure, or chemical stress.

On 1 January 2020, IMO 2020 came into force, limiting the global sulphur content in all marine fuels from 3.5% to 0.5%.

This meant a new type of fuel was required for marine fuel users.

To adhere to the new regulation, the industry started to blend HFO residual streams with stable distillate grades to produce 0.5% sulphur fuel oil, known as very low sulphur fuel oil or VLSFO. However, blended VLSFO can result in fuel instability and high sedimentation in the tanks.

Therefore, using VLSFO may eventually lead to difficulties such as stability issues.

The asphaltene content in VLSFO will become unstable over time, having clustered together. These clusters will mutually interact to form larger cluster structures and fall out of VLSFO, causing sludge accumulation in the fuel system which leads to compromised purification.

Failure to purify effectively can pose considerable damage to the engine.

Compatibility is another issue associated with VLSFO. Fuel co-mingling during bunkering or switchover can result in fuel incompatibility and instability. This will in turn trigger excessive sludging which impacts not only operations but also fuel wastage.

Finding a balanced VLSFO for trouble-free operation can be difficult to achieve.

But with Infineum sludge management additives, you can tip the balance in your favour.

Infineum sludge management additives work in dual mode. Firstly, these additives are powerful asphaltene dispersants. They prevent the asphaltenes from coming together to form larger clusters and fall out as waste sludge.

Secondly, these additives can break apart any preform asphaltene clusters in sludge and disperse them, thus making unusable fuel, usable again.

Another benefit is that these fuel additives have the ability to improve the separation of catalytic fines from VLSFO in the purifier.

To assess the operability of these additives, Infineum has been evaluating the fuel oil spin test.

Alfa Laval has correlated the performance of the spin test to real-world fuel performance in its purifier equipment used on board ships.

The spin test demonstrates Infineum sludge management solutions deliver clear operability benefits, specifically in enabling fuels to be effectively processed through the ship's purifier which maximises the amount of usable fuel, while minimising the crew’s time spent on maintenance of the fuel system, and costs associated with sludge disposal.

The drive towards more sustainable operations is gaining momentum.

Infineum sludge management additives can help you optimise your on board fuel performance, enabling a more sustainable marine future.