Fuel testing experts discussed issues with handling marine fuels that have come to the fore this year with sulphur cap-driven switch to very low sulphur fuel oil (VLSFO) during Riviera’s Fuel testing in a new age webinar
Lessons still need to be learned and additives need to be tested to overcome these issues, which are caused by differences in fuel properties and chemistry between VLSFO and heavy fuel oil (HFO).
This was one of the main conclusions from the Fuel testing in a new age webinar, held no 26 November as part of Riviera’s Marine Fuels Webinar Week, where panellists included Intertek Lintec global technical manager Tracy Wardell, Innospec technical services engineer for marine fuel specialties Joshua Townley and Veritas Petroleum Services group commercial and business development director Steve Bee.
Following the introduction of IMO regulations in January 2020, there has been a pronounced switch around global fleets from HFO to VLSFO, which Ms Wardell said has led to more issues with handling fuel on ships. Some of these issues come from the changes in levels of paraffins (alkanes) versus aromatics (such as benzene) in VLSFO versus HFO, which leads to stability and flow issues.
Ms Wardell also highlighted regional differences in VLSFO quality and attributes such as viscosity, density, pour point and flash point. Operational issues also include deposition of solids on cylinder heads and failures in piston rings. “Ongoing issues on board are sludging during purification, cold flow issues and microbial contamination,” said Ms Wardell.
These issues and others have led to engine damage and handling problems, said Mr Townley. He said since the industrywide switch to VLSFO, there have been more engine failures and issues.
“No one anticipated the increases in engine damage,” said Mr Townley. “Some are still suffering ongoing issues with most damage occurring when using higher density fuels with high viscosities.”
Engine problems include piston ring breakage, injector failures, liner wear and scavenge fire.
There have also been more fuel handling problems on ships, especially with lower viscosity VLSFOs, mostly through blocked filters and separation failure.
Mr Townley said part of the reason for handling issues and engine problems comes from the higher paraffinic content or single-chain hydrocarbons in VLSFO versus HFO.
“Paraffins are prone to rapid oxidation when heated, or drop out as wax in low temperatures,” he said.
This leads to cold flow issues and the deterioration of VLSFO over time. Lower aromatic content in VLSFO means asphaltenes begin to agglomerate and increase in size, forming sludge in tanks and attributing to poor combustion,” said Mr Townley. He said additives such as Octamar will prevent paraffin oxidation and reduce asphaltene growth.
Other issues in fuel stability, handling and combustion could come as ships begin to burn more biofuels in the future. Mr Bee outlined the positive and negative points of using biofuels, or blending in biofuels with marine fuels in the future.
He said biofuels have lower emissions of greenhouse gases, SOx and NOx, so there would be no need to retrofit ship engines, and existing infrastructure can facilitate bunkering. However, there is the risk of water contamination, risk of microbial growth and long-term storage issues.
Despite the risks, 71% of the webinar attendees agreed the use of biofuels should be a consideration in the short term and 80% thought IMO’s emissions reduction objectives are achievable.
Mr Bee expects shipping companies to consider alternative fuels to enable the industry to meet IMO’s objectives to reduce carbon intensity by 40%, from 2008 levels, by 2030 and 70% by 2050. IMO also aims to cut greenhouse gas emissions by 50% by 2050.
Alternatives include using LNG, methanol, LPG, ammonia and hydrogen.
More than two-thirds of attendees think natural gas will not be a long-term alternative to fuel oil with only 30% thinking LNG offered a long-term solution to decarbonisation.
Other interactive questions in the webinar polls covered the use and challenges of VLSFO and HFO.
Almost 60% of attendees thought VLSFO causes more issues than traditional HFO, with 18% disagreeing and 24% unsure.
Attendees were then asked: When it comes to fuels, which property would you most want to improve by using a targeted chemistry? To this, 32% said vessel operability and reliability, while 27% said improved and consistent combustion and reduced fuel oil consumption, 22% wanted reduced emissions and post combustion fouling and 19% asked for reduced unplanned maintenance and spare parts costs.
There was a mixture of answers from the question: If you could improve the quality of VLSFO, which quality would you prioritise?
Around 32% wanted better combustion efficiency – for reduced fuel consumption, CO2 and NOx emissions and less risk of engine damage.
Another 27% wished for better reliability – with more consistent fuel quality and less variability between batches; 25% would want improved fuel stability and less waxing – for less sludge in purifiers, filters and tanks; 11% asked for better comingling, mixability and compatibility; and 5% wanted longer periods in storage without instability.
Webinar Fuel testing in a new age panelists were: (left to right): Innospec technical services engineer for marine fuel specialties Joshua Townley, Veritas Petroleum Services group commercial and business development director Steve Bee and Intertek Lintec global technical manager Tracy Wardell