IMO NOx emission regulation Tier 3 will come into force and will require NOx reductions in marine low speed two-stroke diesel engines below a cycle value of 3.4 g/kWh in Emission Control Areas. To comply with this regulation, a combined EGR (exhaust gas recirculation) & WEF (water emulsified fuel) system has been developed to effective reduce NOx with minimum penalty in fuel oil consumption. The test engine was a Kawasaki-MAN B&W 2S50ME-C. The turbocharger cut-out system and VT (variable turbine nozzle area) turbocharger incorporated with the EGR system enabled the reduction of NOx with minimal impact on fuel oil consumption. A wet scrubber which is also incorporated with the system removed SOx and PM in the re-circulating gas, thus preventing corrosion and contamination in the scavenging air system during EGR operation. Water treatment system which is one of the most important systems for EGR was developed to effectively remove PM from the washing water out of the scrubber using a special compact settling tank.
Based on the quantitative analysis of biocide leaching rate and biomass measurements, the impact of sessile organisms on antifouling coating systems (AFCS) were investigated. The leaching rate of biocide from AFCS was measured by in-situ sampling instrument that enabled direct sampling from test specimens. At the same time, the biomass of sessile organisms, which were identified as fouling organisms, was measured by barnacles and chlorophyll-α (Chl-a) extracted from algae. Test specimens with commercially available AFCS were immersed at two experimental sites in Tokyo bay for almost 1 year. The results show that the leaching rate for copper-based biocides varied from 10μg/cm2/Day to 40μg/cm2/Day under fouled states. In the case of AFCS test panels, the concentration of Chl-a was lower compared to that of the control panel, and furthermore, no barnacles were found. These facts imply that leaching phenomena of biocide from AFCS demonstrated an antifouling property even in a static state simulated under anchorage conditions for 1 year. Use of the methods of ocean-immersion tests may be a good starting point for the evaluation of the antifouling properties of AFCS.
It is well known that marine fuels have been getting heavier and lower in viscosity resulting in poorer combustion quality for the last 10 years. In this study, the effect of chemical composition of residual fuels on its ignition and combustion quality was investigated. Residual fuels are mixture products consisting of vacuum residue (VR) and some intermediate products of oil refinery process; straight-run light gas oil (LGO), vacuum gas oil (VGO), FCC light cycle oil (LCO), and FCC clarified oil (CLO). The blend compositions were estimated by thermal and chemical analyses, by using thermogravimetry (TG) and gas chromatography / mass spectroscopy (GC/MS), and discussed with the results of combustion characteristics, by using Fuel Combustion Analyzer (FCA). The fuel ignition quality is significantly affected by the amounts of both 2-ring polycyclic aromatic hydrocarbons and relatively lower molecular weight alkane series (C13-C21), which are interpreted as the amounts of LCO and LGO.
To improve the tribological properties of sliding surfaces, various surface treatment methods are used. Fine Particle Peening (FPP) is one of the methods which have attracted considerable attention recently. In this study, a SiC-rich layer was created on the treated surface of carbon steels (S45C) by FPP using SiC shot particles (average diameter: 19,34,88 μm). The tribological properties of the FPP treated carbon steels were examined by sliding experiments. The experiments were performed in the atmosphere and 3% NaCl solution. A ball-on-disk type testing equipment was used in the sliding experiments. These were carried out under a normal load of 20N at a sliding speed of 0.1m/s and a sliding distance of 180m. The results show that the tribological properties of the FPP treated carbon steel were improved in comparison with FPP untreated ones. Further improvements were obtained by buffing.
A bolt heater is frequently applied to tighten large and critical structures with large bolts that cannot be clamped by any other means. In addition, multiple bolts can be tightened simultaneously by using the same number of bolt heaters. When bolt heaters are used for tightening large bolts, they are usually placed vertically because the target bolts are installed in the same vertical direction. In this study, the applicability of horizontally plated bolt heaters is examined to promote its broader use. It is found from tightening experiments that the bolt heater technique can be applied for bolts placed horizontally or on an inclined plane. Based on the experimental results, a guideline is proposed for the cases of bolt heaters used in the above-mentioned manner. It is also shown that the bolt heater technique can be an effective assisting method to JIS B2251, “Bolt tightening procedure for pressure boundary flanged joint assembly”.
An effective combustion technique is required to utilize low sulfur and low ignitability fuels, such as Light Cycle Oil (LCO). The objective of this study is to experimentally investigate the cold startability, engine performance and combustion characteristics of five different types of fuels. These fuels have different cetane indices which were varied by the relative volumetric percentages of LCO and diesel fuel. In addition, the evaluation of pilot injection as a means to reduce the maximum rate of pressure rise was also conducted. The results show that LCO fuel blends with cetane indices up to 35 gave better cold startability and combustion characteristics. The pilot injection close to the main injection improved the maximum pressure rise independently of cetane index. Increases in the degree of constant volume and the maximum rate of pressure rise led to higher NOx and Soot emissions, respectively.