Aderco group technical director Olivier D’Olne talks about the potential of his company’s latest product to reduce sludging, waxing and other issues associated with VLSFOs
Is VLSFO so different from traditional, high-sulphur fuel? It is an interesting question and a difficult one to answer. In many ways it is. VLSFO is a blended fuel oil; it contains more paraffinic extremes and less residue streams and the latter is desirable in the new VLSFOs.
But on the other hand, it is not so different to high-sulphur fuel because most of the issues the industry faces today are the same as before 1 January 2020. Priorities and order may have changed but we are still discussing many of the same concerns.
Aderco has over 40 years’ experience in this area and we are very familiar with the current themes affecting VLSFO, which include sludging, stability, cat fines, asphaltene and compatibility.
Our Aderco 2055G fuel conditioner has been developed with these issues in mind, coupled with the relatively new concern of waxing for very low viscosity fuels.
One of the key characteristics of the current crop of VLSFOs is the very wide fluctuation in viscosity. In our opinion this is normal, as blend components vary widely; there are a lot of components with the potential for many different mixes.
For a better understanding of this issue, it is helpful to place VLSFOs into three categories: category one includes viscosity from 5 cSt to 60 cST and contains more paraffinic fractions with high stability issues, more waxing, a high pour point, a high TSP, chemical contaminants and additional commingling risk.
Category two is for a viscosity ranging from 61 cSt to 120 cSt and includes a mix of paraffinic – light and heavy aromatic fractions. Here we see moderate stability, some compatibility issues, commingling risk with category one and chemical contaminants.
Finally, category three is for viscosity 121 cSt to 300 cST and includes mostly a mix of light and heavy aromatic fractions that demonstrate potential stability issues, with superior TSP and commingling risk with category one; paraffinic fractions can cause issues here.
One of the main issues we are facing with VLSFO is compatibility between these three categories and the potential for sludging that arises as a consequence. We have run drop tests in our laboratory for the different categories to better understand and address this issue. By early March this year we had collected many fuel samples from on board vessels and built up a considerable library of samples.
For our Category one, we compared the drop tests with and without the Aderco 2055G product. We discovered that without the conditioner the fuel contained quite a lot of paraffinic fractions; but with Aderco 2055G added, the aromatic dispersion was far better.
Aderco 2055G is 100% vegetal-organic, ashless, and solvent and metal free. It is classified as non-hazardous and there are no transport restrictions in place on it (the flash point is > 146°C). It is compatible with HFO, HSFO, VLSFO, MGO/LSGO/ULSGO and is REACH compliant, BV attested, has a DNV GL statement of fact and is EPA registered.
It is clear from our experience that the improvement in stability is a very important one, and a continuous fuel treatment process will keep the fuel storage tanks clean of sludge. Another benefit of using Aderco 2055G is its water demulsifying action, which helps eliminate cat fines.
We have been asked how best to handle Category one low-viscosity fuel bunkers, where the bunker has been received and a sample analysed in the laboratory. Is it then reasonable to use additives at this stage and how practical is it to use an additive at this stage? We strongly recommend using an additive with low-viscosity VLSFO. Low-viscosity VLSFOs are especially reactive; in our testing we demonstrated that as soon as you have a high proportion of Category one and you mix it with a Category three – a more aromatic fuel – then strong incompatibilities are likely to occur.
There is a tension between aromatic and paraffinic fractions and our recommendation for using a fuel additive for low-viscosity fuels stems from the fact that few operators or owners have a choice of which fuel arrives on board. There are not many companies which can decide exactly what type of viscosity they will get; it is more of a charterer choice. As such, you can end up with a mix of low viscosity and high viscosity, with significant consequences in terms of sludging.
It is also often asked why, if an additive is necessary, does the supplier not add it? This is a legitimate question, but it is worth noting that the majority of fuels delivered on board a vessel adhere to the agreed specifications and are of good or average quality.
You should consider fuel treatment as an insurance. For instance, if something goes wrong, if there is a full breakdown mid-way across the Atlantic, it will cost a huge amount to resolve the problem. You might end up having to open the fuel purifier every hour to clean everything, or with sludge tanks that are completely full.
Fuel treatment is an insurance against this. But of course, if you have a very good supplier, then you can be sure of the quality of the fuel.
The Riviera Fuel additives and blending webinar was held 29 June 2020. Watch this in full in our webinar library