The CIMAC congress had a very interesting discussion on a range of issues shipping industry is currently sailing through. Viswa Group in a 4 part series, have selected below technical papers presented in CIMAC congress. Here’s the essence of those interesting papers.
Paper 264: Fuels of the Future – Service Experience with New ≤ 0.50% Sulfur Marine Fuels – Case Studies by Ronald T. F. Jukes, Chevron Oronite
Blending of VLSFOs
To be able to continue to meet the needs of the shipping industry in 2019 and beyond, Chevron has been evaluating options for blending VLSFOs for some time. Chevron and MAN Energy Solutions collaboratively set up a project to test three promising candidate VLSFOs in the field, in combination with appropriate lubricants.
Three candidate testing
Three candidate VLSFOs blended by Chevron were tested extensively, all three fuels meet the ISO 8217:2017 specification for RMG 180, show good stability, and have good combustion properties.
The fuels were also found to be compatible with each other. A successful > 4,000 hour field trial was run on VLCC Leo Voyager, during which both the main engine and the auxiliary engines were operated on these VLSFOs.
These results show ship operators should not have to worry about the stability or combustion properties of VLSFOs, as long as fuel suppliers carefully select the right blend components for the fuels.
Preparation for transition to VLSFO
Although this project shows that vessels can be operated successfully on VLSFO, it is nevertheless important that ship operators prepare well for a transition to VLSFO. The fuels tested in this study were found to be compatible, but given the expected variety in fuel blend formulations to come into the market, it is not a given this will be true for all VLSFOs.
Recognizing that some degree of mixing between fuels onboard a vessel cannot be totally excluded, segregation of different fuels should be considered to minimize the risk of compatibility issues.
Results from this project also indicate that some VLSFOs have significantly higher potential for fouling up engines than others. It is therefore important to select robust lubricants that are able to handle the expected fuel variability.
Paper 296: Potential of Pilot‐ and Post‐Injection Strategies in Large Diesel Engines Using Maritime Fuels by Benjamin Stengel, University of Rostock
In this study engine tests were performed at a large diesel engine using diesel fuel and residual fuel in order to investigate the possibility of multiple injection strategies to reduce engine emissions. Steady‐state engine tests were performed at different engines loads and constant engine speed.
Fuel impact and impacts of the injection strategies on engine operation, combustion and emissions were studied through measurement of in‐cylinder pressure and exhaust emissions.
Reduced ignition delay
It could be observed, that in standard single‐injection mode, combustion of residual fuel is characterized by an increased ignition delay, and clearly increased NOx and soot emissions at low load compared to diesel fuel. Specific NOx emissions were highest at low load for both fuels as combustion is almost entirely premixed.
Applying pilot‐ injections can significantly reduce ignition delay, heat release during premix phase and thus lower NOx emissions. Especially early pilot injections with distinct pre‐combustion led to drastically decreased NOx emissions for both fuels while soot and fuel consumption increased.
Impact of pilot‐injections on emissions was generally stronger with RMH 700. It was found that late pilot‐injections, for both fuels, effectively shortens the ignition delay leading to a more efficient position of the centre of combustion resulting in both NOx reduction and decreased fuel consumption but increased soot emissions.
Paper 344 Fault Diagnosis Study on Combustion Chamber Components of a Marine Diesel Engine by using Acoustic Emission Technology by Yonghua Yu, Wuhan University of Technology
Acoustic emission (AE) signals of marine diesel engines contain a lot of information about the faults of the engines and the AE technology has been expected to have a better prospect in marine diesel engines’ monitoring and diagnosis due to its unique advantages of non‐destructive and high signal‐to‐noise ratio.
However, more studies are needed on how to determine the fault location and severity of the combustion chamber components through a single sensor by selecting an appropriate installation position.
Diagnose injector clogging and exhaust valve leakage
Combining the above signal characteristics, the four characteristic parameters Ec, n1, n2 and n3 can effectively distinguish the three states of normal, injector clogging fault and exhaust valve leakage fault, so the characteristic parameters can be used for diagnosis for injector clogging and exhaust valve leakage fault.
It has been found that different faults of the combustion chamber components have different effects on the AE signal of the cylinder head, and it provides a technology reference for the application of AE technology in the non‐destructive monitoring and diagnosis of diesel engine components.
Paper 306 The Development of a 40 BN Cylinder Oil and Experience with a Variety of Low Sulphur Marine Fuels Meeting IMO’s 2020 Sulphur Cap by Luis Garcia, Shell Global Solutions
Engine manufacturers recommendations have long existed for the lubrication of low speed 2‐ stroke marine diesel engines when operated on low sulphur fuel oils (e.g. < 1.5% m/m sulphur), where typically a ≤ 60 BN cylinder oil is advised.
More recently, recommendations for lubricating these engines when operating on ECA compliant fuels (e.g. distillate fuels) have also been issued and experience with these recommendations is still being made due to the high variability in quality amongst the ≤ 0.1% m/m sulphur ECA fuels and the introduction of more efficient but also more demanding engine designs. Currently, engine makers suggest 40 BN cylinder oils are suitable for a 0.5% m/m sulphur level.
Countless compliant marine fuel compositions
The majority of commercial 40 BN cylinder oils have been developed nearly two decades ago and experience with these products lubricating 2‐ stroke diesels has been acceptable but generally limited to intermittent and much less continuous use of residual fuel oil with sulphur levels above 0.5% m/m and typically between 1% m/m and 1.5% m/m (ECA 2005‐2014).
It is likely the 2020 sulphur cap will result in innumerable ≤0.5% m/m sulphur marine fuel compositions being developed by fuel blenders (traders) and refiners, depending on available crude sources, refinery configuration and (regional) market conditions.
Note: Wait for the final set of such papers in the next update from the Viswa Group. This is part 3 of 4 of our series of CIMAC 2019 Congress Updates.
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Source: Viswa Group