Most of the 0.5% sulphur very low sulphur fuel oils (VLSFOs) used after 1 January 2020 will be residual fuels, not distillates, said Dr Markus Hoffman, Alfa Laval’s global application manager for marine fuels and lubes.
He was speaking last week (27 March) during a ShipInsight webinar titled ‘The fuel line for today, 2020 and beyond’ and warned that these fuels will suffer from contaminants such as catalytic fines, asphaltenes and water, just as current fuels do.
But he predicted that their distribution in future fuels will be more unpredictable. One port might supply fuel that has low levels of catalytic fines, while stocks in the next one could have very high levels, he said. As a result, “you need a proper fuel treatment system on board to be able to handle this range of catalytic fines.”
Asphaltene content, on the other hand, is likely to be less than in HFO perhaps around 2% compared with about 8% in HFO. That is a big improvement, but “2% is still a lot if it comes out [of solution],” he said. That is a risk if a ship is carrying unstable fuels and his webinar presentation included photographs of two separators that had been opened, one revealing a black sludge caused by asphaltenes precipitating out of the fuel while the other was blocked with a large wax deposit.
“Wax is a really good fuel if it’s liquid but, if it’s solid, it’s a perfect insulator and you will not get it back into solution,” Dr Hoffman said.
Wax can form if the fuel is not hot enough, which could be a risk with low viscosity fuels that shipowners believe will not need heating. In fact, he predicted that fuel viscosities will vary widely, perhaps to as high as 500-600cSt, so “we always recommend that owners and operators should make sure that their fuel is always at least 15°C above its pour point” to avoid waxes forming, he said.
Density will also be variable in the future, he predicted, because suppliers will use more paraffinic cutter stocks to blend down a fuel’s sulphur content, which will decrease its density. But density affects the performance and settings on separators and other equipment on board, he said.
Not only will fuel specifications become more challenging, the number of fuels carried will also change. Instead of one or two fuels at present, ships might carry three or four fuels, believes Niclas Dahl, head of marine separation at Alfa Laval, who also took part in the webinar.
This adds further complexities to how fuel will be handled, since each fuel will need to be handled differently as far as their heating and cooling is concerned. They need to be managed and stored separately to avoid compatibility and clogging problems; “in the past it was simpler,” he said.
He described Alfa Laval’s fuel conditioning module (FCM), in particular its latest model, the FCM 1.5, which can manage up to four fuels, each with their own characteristics. “It gives us a controlled fuel changeover” that can be managed “in a fast and very safe way,” he said. It has a 10μm Moatti filter on the hot side of the equipment, which he described as “the last line of defence before the engine.”
The company also makes FCMs for low-flashpoint fuels, which have been developed with MAN Energy Solutions. The first was launched in 2014 to handle methanol and the two partners have now produced a version that can handle LPG, to accompany MAN Energy Solutions’ ME-LGIP engines. “We are now ready to put this into the market,” Mr Dahl said.
Because of the expected range of fuels in the future, Alfa Laval has developed what it calls its adaptive fuel line, which was developed because “we need to adapt how we operate the fuel line depending on fuel types,” he said. It relies on data from various pieces of equipment to optimise the whole fuel line. For example, the FCM will provide such data as the fuel’s density and viscosity which will help optimise the separator’s performance and efficiency.
This approach “has enabled us to work more with smart separation and fully automatic changeover between different kinds of fuel,” Mr Dahl said. “But we are still only in the beginning of this journey,” he went on. With more connectivity and data sources, “we can measure and optimise this even further.”