142 | FUELS TREATMENTS AND ADDITIVES
fuel lines and injection gun systems, sometimes over years. It is not possible to pour 2020-compliant fuels on top of the sludge because it breaks up the residues, which then work their way through the main engines and auxiliary power systems, causing blockages in filters and purifiers. So how to get rid of it when ships switch over to non-HFO or cleaner HFO fuels? Until recently, the only way was to take the ship out of action while the tanks were cleaned in an expensive and timeconsuming exercise. However, Innospec has developed a product that it claims allows the tanks to be cleaned while the vessel is under way. This could have a huge impact on costs and fleet management, allowing engines to practically clean themselves during operation. The pursuit of the right treatments and additives is endless, with experiments going on constantly in the background. In early 2017 at its Marine and Power Innovation Centre in Hamburg, Shell tested the properties of an Innospec product, Octamar Complete, designed to improve specific fuel oil consumption (SFOC), stability and emissions. According to the company, the results showed an average SFOC reduction of 1.6% across the power range and a maximum reduction of 2.2% at half load. Furthermore, the product was able to reduce the emission of particulate matter by 60%.
The problem of supply
One of the main underrated challenges is that of supply. How much of each kind of oil and lubricant will the world’s shipping fleet require? It is a complex issue that goes right back to the refineries. Shell Marine anticipates up to 3M b/d of HSFO will be displaced by low-sulphur fuels, which clearly involves huge adjustments in supply. It has already implemented most of its two-stroke portfolio and is working on the rest, but there are many kinds of oils to consider. The company has recently
“Over the years fuel additives have developed a questionable reputation in the shipping industry, due to the actions of a few unscrupulous suppliers”
Balearia Ferries expects to spend US$70M on gas-powered engines
upgraded its four-stroke crankcase lubricants – Shell Gadinia and Shell Argina – noting in a technical paper titled Shell Marine prepares for more cylinder oil uncertainties, that “The new oils have been optimised to deal with the faster viscosity increase and the base-number depletion experienced by oils in modern medium-speed engines.” Similarly, ExxonMobil has come up with Premium HDME 50 that meets all the lowsulphur regulations. “[It] has no residual material, which leads to cleaner engines without cat fines,” the company reports. ExxonMobil also claims excellent ignition quality for the fuel.
Catalytic fines
Commonly shortened to “cat fines”, catalytic fines are tiny particles about the diameter of a single human hair. Created by the catalytic cracking process employed in refineries, they are composed of aluminium and silica, which are elements used in the process. Some of the particles are carried over into the residual oil via the slurry oil. Nearly as hard as diamonds, cat fines can cause a lot of mechanical damage despite their microscopic size. Measured on the Mohs scale of mineral hardness
Marine Propulsion & Auxiliary Machinery | August/September 2018
used by scientists, they are nearly twice as hard as the iron and steel used in engines. And unfortunately, they are becoming more prevalent in fuel because they are produced as a side effect of low sulphur fuels. Two-stroke engines are the biggest victims. As Wilhelmsen reported in an early 2018 study entitled Between a rock and a hard place – catalytic fines in fuel “The damage caused by catalytic fines is almost exclusively seen in two-stroke engines.” In fact, some two-strokes have been put out of action in less than 100 hours by this issue. Rough weather tends to bring the contaminants into play because they get shaken free from the sediment in the bottom of fuel tanks. An exhaustive study last year by ExxonMobil, titled Explore the outlook for energy – a view to 2040, which looked at more than 400,000 oil samples, revealed that 43% of vessels had enough of these impurities in their fuel to trigger serious engine damage and even catastrophic failure. Lloyds Register’s Fuel Oil Bunkering and Advisory Service (FOBAS) also identified “significant problems” with catalytic fines in bunker fuels. In samples taken at Fujairah bunkering port in ➤
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