Senichi Sasaki

ClassNK Requirements and Tendency of Damages on Shafting and Diesel Engine

Over the years, ClassNK has made extensive failure investigations and incorporated the results into the classification rules, and presented the information on failures to other concerned parties. The objective of the presenting this information is to share the knowledge between related parties in order to avoid the future failures, and this paper was prepared towards this aim. In this paper, case studies on propellers, crankshafts, main engine bearings and coupling bolts have been selected as a failure in marine propulsion systems. The case studies together with detailed information including the results of investigations and the cause of failure will be of interest to marine engineers and other concerned parties.

Combustion Tests of Marine Fuel Oils

The combustion characteristics (ignition delay and combustion period) of heavy fuel oil (HFO) for marine diesel engines may be affected by many factors such as density, carbon residue, asphaltene content, aromaticity, carbon/hydrogen (C/H) ratio, and so on. Investigation of the causes of operational problems in marine diesel engines should include examination of the fuel oil in service. The present study investigated the most important properties of HFO for such examination, using combustion tests and oil analysis. Marine HFOs with and without problems were analyzed using the same oil analyses and combustion tests. This study also tried to identify any threshold value of a fuel oil property related to poor ignition delay and combustion period. The constant volume combustion test apparatus (FIA 100), which has the same fuel injection mechanism as a diesel engine, was used in all the tests. This study reached the following conclusions: (1) Percentage of paraffinic carbon (%Cp) and C/H mass ratio of marine HFO have a good correlation with the combustion characteristics. (2) Density has a higher correlation with the combustion characteristics than viscosity. (3) Carbon residue and asphaltene in fuel oil have lower correlations with ignition delay, but some correlation with combustion period. (4) Sulfur content has a low correlation with the combustion characteristics. (5) Threshold values of C/H mass ratio = 8.3 may indicate ignition delay and prolonged combustion period in fuel oils of poor quality.

Study of Combustion Characteristics of Marine Fuel Oil Containing Used Lubricating Oil

of Journal of the JIME Vol.39. No.5 ©JIME 2004 Study of Combustion Characteristics of Marine Fuel Oil Containing Used Lubricating Oil Takaaki Hashimoto; Senichi Sasaki *1: Nippon Kaiji Kyokai (ClassNK) Research Institute, 1-8-3 Ohnodai Midori-Ku Chiba, 267-0056, JAPAN E-mail: t.hashimoto@classnk.or.jp *2: Nippon Kaiji Kyokai (ClassNK) Research Institute, 1-8-3 Ohnodai Midori-Ku Chiba, 267-0056, JAPAN E-mail: sen.sasaki@classnk.or.jp Marine fuel oil is generally supposed to be free of used lubricating oil, but bunker oil sometimes contains used oil. Treatment of waste oil generated on board ships is very important. Although waste oil is usually burned up in an incinerator, such waste oil as used lubricating oil is sometimes mixed into fuel oil and reused as energy. This paper reports a study of the combustion characteristics of fuel oil mixed with engine oil used in-house. We found that harmless combustion of fuel oil containing 5 % or less used engine oil is possible.

Study on the Relationship Between Combustion Characteristics and Properties of Marine Heavy Fuel Oil

The combustion characteristics (ignition delay and combustion period in this paper) of marine heavy fuel oil are affected by many factors such as density, carbon residue, asphaltene, aromaticity and carbon/hydrogen (C/H) ratio. When investigating the causes of operational problems in diesel engines, what properties should we check to find whether the main causes of the problems are related to fuel oil or not? What is the threshold of ignition delay and combustion period of fuel oil? The authors studied these topics using a combustion test apparatus called FIA 100, and arrived at the following conclusions: 1. The aromaticity index (CCAI) and the C/H ratio have good correlation with the combustion characteristics of marine fuel oil. These factors cannot be ignored during troubleshooting. 2. The carbon residue and asphaltene in fuel oil have no correlation with ignition delay, but have some correlation with the combustion period. 3. There is practically no correlation between the average molecular weight of fuel oil, and both ignition delay and combustion period. 4. Tentative threshold values of ignition delay and combustion period can be set for fuel oils of poor quality (flame retardation).Copyright

Study on Arrangement of Fire Detectors in Engine Room of Ships (1 st Report)

In ships engine room, many fire detectors are positioned for rapid detection of the onset of fire, and most of them are smoke detectors. The purpose of this study is to present a guidance for the arrangement of smoke detectors under the actual ventilating condition in engine room. As the 1st report, this paper shows the performance results of smoke detectors in some fire tests based on the combustion of marine fuel oils. In the tests, the effects of height of detectors above fire source and the speed of ventilation air were investigated.In addition, considering fire alarm tests on board, we proposed the method of fire test using smoke signals for automobiles which is equivalent to fire test using marine fuel oils.