We developed the method of approximate calculation of the percentage of paraffinic carbon (%CP), the percentage of naphthenic carbon (%CN), the percentage of aromatic carbon (%CA) and the average number of naphthene ring per molecule (RN), the average number of aromatic ring per molecule (RA) from density g/cm3 @15°C, kinematic viscosity mm2/s @50°C and mass % sulfur content of marine C heavy fuel oils. It be possible to distinct the property (straight series, visbreake series, FCC series) using this method and as the results, it will be possible to guess from enginetroubles before the fact, and the countermeasure of prevention will be accepted properly. The method for calculation distribution and structural group analysis of petroleum oils from density, refractive index, average molecular weight and sulfur contents is defined by ASTM D3238. On this method, the inconvenience appears that it couldn't apply to residual heavy fuel oils having high sulfur contents. In that place, we developed the method applicable to petrolume less than sulfur content 5.0wt%.
Two types of improved new cylinder lubrication systems, Alpha lubrication and SIP lubrication, are intro-duced. According to the author's simulation results, conventional lubricating system supplies oil mainly under the piston rings and the oil is easily wiped down by the rings. Alpha lubricator supplies the oil mainly between piston rings and oil is retained during more strokes than conventional lubrication. Tests on actual engines with Alpha lubricator proved reduction capability of oil consumption without deteriorating cylinder condition. SIP (Swirl Injection Principle) lubricator sprays the oil onto periphery of upper cylinder liner and forms thin spread oil film. The tests on board proved reduction capability of oil consumption with excellent wear results. This special edition also carries an article on SIP lubrication.
The authors have succeeded in developing a new technology which makes it possible to use lubricating oil (LO) semi-permanently without oil renewal and without waste oil. The technology was developed based on the authors' belief that LO oxidation is negligible and that LO may be used semi-permanently if sludge removal is speedy enough and LO is always kept clean. The technology is called kidney system and it has been working well in more than 1000 units of marine and cogeneration diesel engines, in many hydraulic machine com-panies and in many machine work-shops Kidney system has been working better than expected in cleaning performance of LO, no waste oil, decrease of LO consumption, increasing load capacity of LO, remarkable reduction of machine troubles, longer life of engines and so on. This paper explains and considers why kidney system is so effective. The paper also shows some new fields where kidney system can be applied. Application to automobiles already started in Tokyo Metropolitan Transportation Agency and the authors hope that kidney system will be widely used in automobiles in the near future.
An actual survey on the performance of stuffing box and rings in marine diesel engines has been made on 7 ships selected from numbers of ships subjected to Mitsui O.S.K. Lines and NYK Line. Samples of the stuffing leak oil (SLO) were obtained from each cylinder of engines in every month from 1999 to 2001 years. Volumetric and chemical changes were observed on all samples. The results obtained are as follows: (1) The most suitable volume of SLO varies from 3 to 7 ml/Day/kW. (2) The most suitable volume of SLO differs with different types of engines. (3) The best performance of stuffing box and rings required are: (1) the contact between rings and the moving piston rod keeps the best condition at all times, (2) every cylinder keeps the most suitable volume of SLO through the long time service, (3) stuffing box and rings prevent completely the leakage of the dirty scavenging drain from cylinder to crank case.
For improving the reliability of main bearing in large 2-stroke marine diesel engine, it is indispensable to grasp the journal movement behavior in main bearing with high accuracy. We have studied to disclose the journal movement behavior. Firstly, the journal movements of actual engines were measured. The journal center locus and the journal tilting angle were clarified. Secondly, a theoretical calculation model has been developed in order to simulate the journal movement behavior under uneven alignment between two adjacent main bearings. For confirming the validity of the model, calculated results were compared with measured results. The model was proved effective to simulate the journal movement in high accuracy. At last, by indicating an actual bedplate deflection owing to the loading of a vessel, the calculated journal movement results under the uneven alignment is compared with measured results. As the results, the developed model is able to simulate the journal movement under the uneven alignment. Considering the circumstances mentioned above, the model is proved effective to simulate the journal movement with high accuracy. The developed simulation technique of journal movement behavior has been applied in practical machinery design for high reliability.