FIA combustion chambers have been used broadly for the testing of the combustibility of various bunker fuel oils. Their ultimate goal is, of course, discriminating good fuels from trouble inducing fuels, but so far not very successfully. There is a lack of a quantitative evaluation method for the combustion process inside them. In this study, multivariate analysis was applied to the heat release curves. For the first time we can characterize the minute differences between the trouble inducing fuel and the normal one. As a result, with 10 variables, much more precise discrimination of good fuels was realized. The reliability high was 95%. However, this figure cannot be trusted fully owing to insufficient samples.
In recent years, the steep rise in the price of crude oil and the demand for light oils; such as gasoline, kerosene and diesel oil, and the increased sophistication of oil refining technology, had led to a tendency towards the production of low quality marine residual fuel oil (hereinafter MFO) . Among the many types of degradation, the deterioration of the ignition and combustion quality of MFO in large marine diesel engines is of particular concern, as this causes such problems as poor combustion in diesel engines. In addition, there is an increasingly greater risk that these problems will be associated with serious problems, such as piston ring damage and abnormal wear on the cylinder liner. The technical information here presents the results of the ignition and combustion qualities, and the general properties of actual marine fuel oil analysis. We used a constant volume combustion chamber instrument (Fuel Ignition Analyzer such as FIA) . Further, we describe the relationships between ignition, combustion quality, and the general properties and engine problems. Examples of countermeasures are described so that these problems caused by fuel oil, with poor ignition and combustion quality, can be avoided.
This paper reviews a number of real incidents whereby fuels, apparently fully meeting ISO 8217 specifications, have caused significant damage to compression ignition engines or given rise to serious operational problems. This reviews the analytical techniques used to identify the root causes of the problems. In particular, a relatively new technique-the FIA-is reviewed. This assesses the ignition and combustion characteristics of residual fuels and how, based on our R & D activities, the data obtained from this technique relates to the engine derived data. Also, reviewed is the mechanism for the scuffing of cylinder liners and piston rings due to poor ignition and the combustion characteristics of marine fuels, together with recommended cylinder oils and the installation of continuous cylinder liner monitoring system. This, in order to prevent scuffing due to abnormal ignition and the combustion characteristics of marine fuels.
An R & D project has been carried out by the National Maritime Research Institute (NMRI) for an oil recovery unit that can be used for ice-covered waters. The mechanical recovery of oil in ice is a difficult problem. Oil spilled in ice-covered waters spreads along the leads between the ice floes. Recovery of such oil requires two different processes: separation of oil from the ice and oil recovery from the water. The first process calls for new ideas, while conventional techniques for open water conditions may be applicable to the second process. The unit developed by NMRI uses air bubbles to separate oil from floating ice floes. This article presents the basic concepts of the unit and some results from scaled model tests performed at the ice model basin at NMRI.
Cavitation bubbles emit a very weak light due to bubble collapse. It is expected that the light emission may be closely related to cavitation erosion. In order to confirm the relationship between the erosion damage rate and the light intensity, experiments were performed for a water orifice cavitation flow. A circular pipe was used and water-cavitation generated around a column. For the measurement of light intensity, photon-counting method was used. And for visualization, the xenon gas-mixing method was adopted this by use of an image intensifier and chilled CCD camera. The damage rate was estimated by counting the number of damage pits. The light emission occurred around the end of cavitation, but the emission pattern was very different from the shape of the cavitation. The profile of the damage area was very similar to the light emission pattern and the maximum damage rate had a strong relationship with the maximum emission intensity.
To minimize the risk to the environment and to human health and arising from the transfer of harmful aquatic organisms and pathogens through the discharge of ship's ballast water, an international treaty has been adopted, February 2004. The installation of a ballast water processing system, which complies with the standard of the treaty, is required for ships constructed after 2009. Via various methods; such as electrolytic, ozone and specialized pipes have been developed. However, the practical application has yet to be achieved. Mud precipitating in the ballast tank, and microorganisms in the mud were observed. The processing burden of the ballast water was examined. By developing a test plant to demonstrate of ballast water processing, and using anthracite filtrating, we have obtained basic data of characteristics of marine organism filtration. The unit showed an effective removal of the microorganisms, excepting pathogens, from the natural seawater. This was achieved with low operational costs and avoided impact to environment.
Propeller shaft diameter of ferries becomes larger in conjunction with requirements of higher vessel's speed and CPPs (controllable pitch propellers) . Thus, it may lead into a tendency to reduce the life duration of stem tube bearing under seawater lubrication. Wear of the propeller shaft sleeve, i.e. bronze alloy, is typically greater than that of the rubber bearings, with triangularly shaped craters appearing on the sleeve surface. In this paper, we describe the investigation of used sleeve sample taken from an actual vessel, as well as the wear characteristics of bronze alloys conducted under the corrosive wear condition which is equivalent to actual ferry service. The results indicated that corrosive wear was the main cause of sleeve wear. Comparing between the amount of wear in seawater and the one in distilled water, the influence of corrosion on sleeve wear was found to be substantial. Additionally, the craters are considered to be formed by the action of erosion corrosion
DME: dimethyl ether is a kind of clean fuel made from natural gas. It is planned that DME will be produced overseas and transported using large-scale tankers. Our plan will contribute not only to the environment, but also to the utilization of medium and small-sized, undeveloped gas fields. Moreover, some DME projects in China, from coal, have now been started. In this study, the combustion characteristics of DME gas, that burned in a full-scale marine boiler, were examined. As a result, DME could be burned with a clear blue flame and emitting much less NOx than regular bunker fuel combustion. Also, almost no CO. However, the heat flux measured in the furnace showed different distributions to that of bunker fuel combustion. It is important to make this clear, for the real application of DME in marine boilers.
Concerning an LNGC Propulsion system: a turbine engine system (the turbine, hereafter) has been selected because it can the more easily treat boil-off Gas from a cargo tank, and would have greater reliability when compared to a diesel engine (the diesel, hereafter) . However, on the other hand, the turbine does have disadvantages, such as lower thermal efficiency and a more complicated operation needing skilled engineers. Recently, what with the rising price of bunkers and greater difficulty in recruiting engineers, some ships have employed the diesel for LNG transportation service. That is the background. Turbine makers have been developing new turbines aimed at improving thermal efficiency. I think that the next range of turbines should be developed with consideration paid to the present, practical operational situation. This paper will analyze the reliability and maintainability of the turbine by using the real maintenance data of an LNGC. Information towards improvement will be offered.