Fuel handling equipment and procedures may need tweaking ahead of the 2020 sulphur cap, marine engine manufacturers say
At Riviera’s Asian Sulphur Cap 2020 Conference, both MAN Energy Solutions and Winterthur Gas & Diesel agreed their engines can burn low sulphur fuels in compliance with IMO’s 2020 sulphur cap without the engines themselves requiring any changes.
At the same time, however, the OEMs have issued advisories to customers about how to handle new low sulphur fuels – procedures they see as the key challenge to owners hoping to successfully navigate the 2020 fuels changeover.
"Will the fuels leave deposits? Will each bunker batch be different? These are the questions," said WinGD director of R&D for combustion systems, Konrad Räss. "Burning sulphur-compliant fuel in the engine is not a problem."
Mr Räss said compliant fuels had not produced any additional liner and piston ring wear rates on engines during testing but that lubricant feed rates and grade may need to be adjusted.
New fuels are likely to be more paraffinic than aromatic he explained, noting that paraffinic fuels can block filters.
Sulphur cap compliant fuels may also precipitate catalytic fines upon blending of different batches of fuel, he said.
Mr Räss recommended operators using more fuel tanks and settling tanks to avoid mixing bunker batches in the tanks. If tanks are not available to store fuel, existing tanks can be split, he advised. This would ensure that two oil batches are stored at different temperatures given that viscosity is expected to vary among the different low sulphur fuels.
To a question on whether fuel injectors needed to be changed for viscosity differences in compliant fuels, Mr Räss said there was no need in the newer versions of WinGD engines.
Ideally, Mr Räss said two bunkers should not be blended on board. Fuel suppliers have greater control over the blending process and the outcome of fuel properties than crew on board vessels. If ship staff have no option but mix bunkers from different suppliers, he said, then the standard spot test could provide useful inputs. Mr Räss said samples of 50-50, 40-60, and 90-10 blends could be tested. A spot test would give an indication of the stability of the blend at the different mixing ratios.
Following his presentation, Mr Räss faced a volley of questions from attendees regarding operating with compliant fuels. Below are a few samples.
One questioner wanted to know if a bunker contaminated with chemicals could crack piston rings, noting the same fuel did not cause sludge.
Mr Räss said a worn liner combined with high pressures could break piston rings and the nature of the contamination could create those conditions.
Another questioner asked about changes needed when running an engine on low load.
Mr Räss’ answer: no changes are required to the engine or its procedures, but keep the auxiliary blower running.
A third question centred on what could happen if very low sulphur fuel (VLSFO) becomes overheated.
Viscosity should be between 13 to 17 cST, he said.
And what about ignition delay due to using VLSFO? It has no impact, said Mr Räss.