The regulation of exhaust emission from vessel was started in Jan. 1st, 2000. The maximum allowable NOx emission limits for marine diesel engine were expressed clearly in terms of the original module for Main & Aux. Diesel Engine. But the proposal of SOx its own is now in the situation being delayed on account of manifold problems. In general, the low quality heavy fuel oil used mainly in ships contains high sulfur content. And then it affects not only the fuel oil cost, low temperature corrosion and engine tribology, but also the formation and emission producing the sulfuric mist in particulate matters (PM) and the dinitrogen oxides (N2O) . This paper studies the combustion characteristics and emissions on the low quality heavy fuel oils. In the experiments, an industrial-scale flame was set up for analyzing it spatially in each flame location. The work indicates that the products at the flame downstream consist of NOx 270ppm, N2O 8ppm, DS and SOF respectively 1.7, 0.5g/mN3, sulfuric acid conversion amount 60-80mg/mN3and SO21000-1400ppm which shown comparatively high concentrations. It is deduced that N2O formation is influentially affected by Fuel·N. The results suggest that DS is dependent upon the particulate matters of gas-phase eduction and the various Fuel·metals, and SOF is the Pre-Soot and unburned droplets from the growing THC.
In order to revitalize sea transportation it is essential to be capable of using low-cost, low-quality fuel oil with simplified fuel systems, the emissions of which must be environmental-friendly. The authors of this paper have developed the blended oil of Marine Heavy Fuel Oil (C-Oil) and pyrolytic oil made of household and industrial waste plastics (hereafter called Waste Plastic Disposal or WPD) and applied it to diesel engines. The experiment on the engine with non-preheated blended oil has shown the stable operation of the engine. This would lead to the significant reduction of heating cost. Furthermore, the emission of soluble organic fraction (SOF) also decreases. This paper discribes the effects of sulfur content on the engine performance and emission. However, NOx emission slightly increases so that the emulsified fuel oil has been made with the aid of capsule-typed additives. The experimental emulsion fuel oil (Emulsion F.O) containing 10% (v) water and 0.3% (v) additives indicates stability and helps to reduce NOx emission almost by half.
As for electric power generation on land, the wind energy conversion system is widely used because of its environmental problems. For the marine environment, some methods to reduce air pollution such as CO2, NOx, and SOx from diesel engines of ships have been discussed recently. In this paper, a study on the application of the wind energy conversion for the electric power generation system of a large ship was carried out. At first, the paper considered and proposed the design procedure of the introduction of the wind energy conversion system to ships. Secondly, a case study was carried out on the wind energy generation system to a coal cargo ship using the proposed design. Finally, in order to evaluate the application of the wind energy conversion system, the fuel consumption and NOx and SOx emission were compared with those of the conventional electric power generation system consisting of diesel engine generator. The electric power generation system could reduce the fuel consumption and NOx and SOx emission from the ship. The application of the wind energy conversion system to the electric power generating system of ship is worth discussing to solve the marine environmental problems.
Genarally, NOx emission from medium-size four-stroke slow-speed engine is high level, comparing to the IMO NOx emission regulation, so some NOx reduction method is needed. In this study, design parameters such as compression ratio, intake and exhaust valve timing, charge air pressure and injection timing are optimized, at first step. The engine performance tendency including NOx reduction effect is investigated from a simulation method, and the engine test using the modified engine components. The result is that NOx emission level is improved below IMO Regulation without drastic modification to the engine, and keeping same specific fuel consumption (SFC) and maximum cylinder pressure level as it is. Also, further NOx emission reduction will be necessary, because NOx regulation will become more and more stringent. So, steam addition system, that adds steam to combustion air and to maintain the absolute humidity at a desired level, is developed at second step. NOx emission was decreased through steam addition, and virtually no decline was observed in SFC.
Increase of turbocharger capacity is desired in order to minimize number of turbochargers per engine, especially for large marine diesel engines. Mitsubishi Heavy Industries, Ltd. has been added the largest turbocharger type MET90SE into their METSE series turbochargers. The capacity of the MET90SE was increased in about 30% than MET83SE turbocharger with minimum increase of external dimension. This is to introduce technical features and test results of the MET90SE.
The safety management in marine engineering has long been supported with the help of skilled workers. Meanwhile, the lack of such skilled workers is of growing problem in marine engineering field and related areas. Incidentally, Computational Mechanics has attained remarkable progress in this decade, and it is expected to be effective means to solve the problem stated above. In this paper, the tightening procedure of pipe flange connection is adopted, as an example of its engineering application. The most critical problem concerned is the estimation of scatter in bolt preloads, when tightening bolts one by one. Such complicated problem could now be analyzed by FEM. In addition, a numerical method offering an optimal tightening procedure is presented here, which estimates how much initial bolt preload is needed for each bolt to achieve uniform bolt preloads in the final state. The numerical method proposed here is expected to partly compensate the lack of skilled workers and contribute the safety management in marine engineering.