In relation to recent tendency of crew's small number, various type of remote and automatic control valves are applied, which are effective in their labor reduction and reliability improvement of system. In this paper, investigation and research about air operated valve shall be reported.
Underwater welding techniques have been of growing importance as a number of new projects for offshore structures are underconsideration and some of them are being put into practice. Underwater“wet type”welding is especially useful for the repair and maintenance of those structures. In the previous paper, fundamental characteristics of wet welding such as heat transfer from plate to surrounding water have been evaluated using mixed gas shield welding, and the extent of heat transfer was quantitatively estimated in terms of coefficients of heat transfer. In addition, three dimensional Finite Difference Analysis was attempted to obtain temperature distributions within the plate. In this paper, cooling process for underwater welding is compared with that for welding in air, where the effects of welding conditions such as welding speed and plate thickness are discussed. It is also shown that the cooling rates for underwater welding could be analyzed within acceptable engineering accuracy using three dimensional FDM.
The flame-spreading phenomenon of combustible soot deposited on the flat plate is one of the basic problems in fire research. The study of the mechanism of burning of the soot deposited on the flat plate and glass wool was done. Therefore, in order to elucidate the soot fire mechanism, it is very important to measure the dissipation rate and luminous intensities profiles of soots. The experimental samples were taken out of the soot formed from various fuel oils and the soot emitted from various combustors. The value of chemical analysis of all the samples was checked quantitively, in advance of the experiments. The main results obtained are as follows: (1) The values of C/H and C/O in the soot formed decrease as the quality of fuel oil deteriorates. (2) The C/H value of soots after washing by water (Exhaust gas economizer) is relatively smaller compared with that before washing in water. The chemical reaction rate increases in accordance with the decrease of C/H value. (3) The cumbustion rate and Surface 1st damköhler number of the soot deposited increase as C/H value decreases. (4) The burning period of the soot becomes shorter as the thickness of attaching plate for soot becomes smaller. (5) The combustion rate rises the more acceleratedly because of the catalyzing reaction as the content of alkali or alkaline earth metals is higher.
The Boiler Study Subcommittee of the Marine Engineering Society in Japan (MESJ) has surveyed the actual situation of production statistics and design practice of Japanese marine auxiliary boilers manufactured around 1990. This paper describes the results of the survey mentioned above and analyzes the recent characteristics of structure, performance and combustion techniques, especially comparing with those of marine auxiliary boilers manufactured in 1970's. The results of the analysis present the progress of space-saving, boiler performance of recent marine auxiliary boilers.
This paper reviews about the vaporization and combusiton characteristics of ethanol-blended diesel oil droplets. Ethanol is soluble in diesel oil at a suitable temperature, so this blended fuel keeps uniform and stable. Analyzing by using a high speed camera, the expansion rate of a droplet increases with increasing ethanol content. Since ethanol has a low boiling point and high latent heat of vaporization, the periods of the droplets vaporization and combustion become longer with increasing ethanol content. However, when we compare the combustion period of 10% blended fuel with the one of 20% blended fuel, we found that difference could be ignored. The reason of this result can be explained as follows. As combustion photographs show, the reduction of the combustion period of 20% blended fuel results from the microexplosion. The vaporization rate of ethanol in a deroplet increase with increasing ethanol content, so we found that this condition is favorable for the microexplosion.