Sound power evaluation methods are investigated numerically and experimentally. Sound measurement in ship's engine room is under very inferior condition because the engine is installed in such a small place. There are two methods to evaluate sound power; sound pressure based method and sound intensity method. The investigation shows that the former method has a inferiority in the precision, especially in the decision of environment correction factor, and the latter method is not practical for a large marine engine. As a result, the hybrid method which has both precision and practicality is proposed.

View full abstract

Safe operation and labor - saving in merchant ships are eternal themes, which have given impetus to the development of automation. In recent years, according to the complexity in ship's plants, the technique of higher advanced automation has been required.
The conventional centralized type monitoring and control system, however, has been limited in performance depending on the processing capacity of CPU, and insufficient in expandability. Therefore, the Distributed Control System (DCS) which has been applied to land use plants but not developed for marine application, is going into use on the ships where highly advanced automation is required.
Under these circumstances, we have developed MHI - DCS which is superior in flexibility and expandability, and suitable for marine use. The system consists of operator station, control station, input/output station, and network.
In the application of MHI - DCS, individual control system onboard can be standardized resulting in better operability and simple maintainability. In addition, since it is superior in expandability, the most optimum system can be composed for every plant. We are confident that this system will considerably contribute to the ship's safe operation and labor-saving in the future.

View full abstract

We aimed to develop a system for treating emulsified oil discharged from ship engine rooms. The efficiency of the system aimed at reducing the oil content of the drain to 15ppm or less so that the drain might be discharged into the sea. We have succeeded in developing a biological treatment system using the fluidized bed in which the drain and sludge are efficiently mixed by aeration and stirring. The specific sludge with enhanced oil decomposing ability is used in the system. We performed on-shipboard tests using a pilot test system, whose capacity of the reaction chamber is 0.5m³ and oil volume load, 0.4kg-oil/m³/d, and have confirmed future possible applications to the treatment system for ships. This would bring great reduction in loads on the existing oil separator, saving its maintenance cost in general.

View full abstract

Recently, it is concerned with the problem of environmental pollution in the world, and the prevention of exhaust emission is enforcing day by day.
The air pollution from vessel is also no exception. The regulation for pollution materials in the exhaust emission from the marine diesel engine will be enforced a few years after. This draft of regulation is now examining, but measurement data have been short and the measuring method itself seems to be unclear.
The purpose of this study is to make an objective technique that measures pollution materials in the exhaust emission from vessel. There are many unknown factors in the measuring method at present yet. But we restrict only the oxide of nitrogen ( common name: NOx ) in this report.
When the exhaust gas measurement is carried out on board, following items must be taken into account with the field condition:
•Practicality, especially portability
•Reliability of measured results
Investigations about following items are described in this report:
•Difference of measured data due to the difference of the measurement principle
•Difference depending whether the sampling tube is heated or not
•Response of the measuring system

View full abstract