In order to cope with stricter environmental restriction, the electronic management of engines used in marine applications, is one of the most effective solution to decrease the antinomy between NOx and CO2 emissions.Electronically-managed two-stroke engines have already been launched in the market. However, a low speed 4-stroke engine of such kind has not yet been introduced because of its cost-performance relationship.The development of this project has been aimed at improving combustion efficiency, reducing NOx , and minimizing cylinder lubricant dosage rate in a wider operating range not only at the rated power zone but also at the partial load zone, by managing electronically the characteristics of fuel injection, intake and exhaust valve timing and cylinder lubricator control, threrby utilizing the inherent advantages of the 4-stroke engine.
The aim of protecting the marine environment, this paper proposed the application of the system combined photovoltaic(PV) power generation with fuel cell(FC) that did not release air pollution gases to the vessel that stayed at the berth. The author considered the operation method of the system. The author designed the new system and carried out the simulation of the operation by using real training vessel. The author calculated the reduction quantity of the fuel consumption, NOx, and SOx emission from the diesel engine generator of the vessel, and discussed some problems that the system was operated.
Ocean-going vessels use oil lubrication in the tunnel thrusters. Offshore vessels also use oil lubrication in the azimuth thrusters. Oil leakage from the thrusters is a serious environmental issue in these vessels. In this paper, a water-soluble, environmentally preferable lubricant newly developed for such thrusters is outlined. Properties required for a thruster lubricant and a suitable base fluid are discussed. Environmental compatibility (biodegradability, low toxicity and no sheen or sludge formation), viscosity, lubricity and seal compatibility of the new lubricant are described. These properties show that for tunnel and azimuth thrusters the new lubricant can improve not only their environmental compatibility but also their seawater tolerance. Field experience of the thruster lubricant is also presented.
Risk-Based Maintenance, hereinafter referred to as RBM, which has previously been adopted for power generating plants and oil refinery plants, is now being expanded to offshore plants, as well. Qualitative RBM has also been introduced as an element of classification surveys for engines and auxiliary machinery of ships as a type of Reliability Centered Maintenance, hereinafter referred to as RCM. However, it has been difficult to apply RBM to rotating machinery because almost all RBM systems are based upon API581 or ASME CRTD standards which are designed for pressure vessel leakage through holes generated by mechanical damage. Nippon Kaiji Kyokai has developed the world's first RBM system for rotating machinery including the main engines and auxiliary machinery of ships. Utilizing past maintenance data, this RBM system provides risk matrixes and can predict future changes to risk levels for different maintenance methods. One study has been conducted using this RBM system on machinery in a tanker. The results of this study show that RBM evaluation provides a practical and transparent method for developing maintenance plans by determining numerical risk which is calculated by the multiplication of failure probability and the consequences of failures.
In 21st century, ship energy system has to be updated not to consider only less fuel consumption but also emission control of NOx, SOx, and CO2 from marine diesel engine. For domestic ship, we proposed new concept of exhaust heat recovery system, consisting of circulating fluidized bed (CFB), and hi-speed radial steam turbine generator. This CFB is smaller than commercial CFB plant and has two-function: heat recovery from exhaust gas and desulfurization by choosing suitable particle. In this report, parameter survey about the CFB and the steam turbine-generator, which are main components of the system, was executed. Supposing water tubes located along riser of the CFB, specification of the CFB like particle diameter and exhaust gas velocity inside the riser, was evaluated to equilibrate the two-functions and gas-particle fluidization. The system was required to add external heat exchanger at upstream of exhaust gas flow, to produce higher superheated steam, in purpose of generating more power output by the radial turbine, based on the evaluation. Furthermore, steam temperature and pressure at inlet of 1st steam turbine-generator, and expansion ratio of all turbines were adjusted to gain more electrical power by increasing degree of superheat. As a result, maximum power became 9.48% of main engine power, in 75% loading factor of 1400kW-class marine diesel engines.
In order to understand the combustion phenomenon in a spark ignition engine fueled with the homogeneous mixture of LPG (main component : Propane) and DME (Dimethyl Ether), the authors previously developed a chemical kinetic model (Propane-DME reduced elementary reaction model and turbulent combustion model) for three-dimensional numerical analysis of the combustion process in the engine. The authors' GTT-CHEM code with that chemical kinetic model was able to reproduce an auto-ignition phenomenon at the last period of combustion in the engine. In this study, the authors have investigated the effects of Propane and DME heterogeneous spatial distributions on combustion in the LPG-DME spark ignition engine by three-dimensional numerical analysis using the GTT-CHEM code with the previously developed chemical kinetic model, for better understanding about the contributions of Propane and DME to the auto-ignition phenomenon. The unburned zone DME fraction and its homogeneity were employed to discuss and explain the results. It is found that a well mixed and highly DME contented propane gas locating at end gas region is in the most danger of strong auto-ignition.
A test hammer is used to detect faulty components or slack bolts during impact inspection of marine diesel engine cranks. Since a prolonged work experience is necessary to acquire this technique, technology transfer is therefore difficult. Moreover, because this technology depends on the individual senses, the inspection accuracy is prone to vary among people. The authors have developed a system that can perform the above-described inspections and execute diagnostic procedures and thereby be more useful than human acoustic sense. We constructed an algorithm that estimates the fastening force of a crank-pin bolt at a connecting-rod large-end from sound, with which diagnostic tests were conducted. However, this algorithm is for a specific bolt only and is inapplicable to bolted joints of various types. This study conducted impact experiments using test pieces with varied component size and bolt tightening torque. First, the test piece size was estimated from impact sound data using discriminant analysis. That result was subjected to multiple regression analysis, a technique of multivariate analyses, from which the bolt tightening torque was estimated. The introduction of this two-step analytical method has provided us with a new tightening torque estimation algorithm for application to various bolted joints.
The authors had proposed a linear motor driven container crane system which could realize a high speed, compact, and low maintenance crane system. In this system, the linear motor is used to control swaying motion of the spreader with the container in addition to drive trolley chassis. We proposed a novel detection method for the swaying angle of the suspended spreader with the container using an acceleration sensor attached to the linear motor driven trolley chassis.In this paper, the fundamental characteristics of the proposed swaying angle detecting method were investigated. Simulated results and experimental data showed the validity of the proposed swaying angle detection method.