After it goes into service of the first domestically “SENSHO” of the Chemical tanker, various kinds of electrical propulsion ship is constructed by an environmental aspect and movement of an economic aspect. Therefore, for development of those new ships, it is a report summary from a shipowner and a building engineer.
Recently several main engine bearing damage incidents have been reported. They are generally said to be related to improper shafting alignments that fail to absorb bearing offset changes between different operating conditions. These damages tend to occur on ships with large draft variations from ballast to fully loaded conditions, such as VLCCs. In this paper, the authors propose a new scientific approach to propulsion shafting alignment taking into account variation in bearing offsets while in service, after conducting onboard ship measurements and FE analysis to determine the hull deflection between different conditions. The results show that static hull deflection arising from draft change can be predicted by FEM with satisfactory accuracy, but a significant dynamic deflection component that is considered to be related to ship motions in waves, and difficult to predict by analysis is also present. The new scientific approach includes a high accuracy alignment calculation model, an optimization procedure for longitudinal placement of intermediate bearing to minimize the sensitivity of shafting to bearing offset variations between different operating conditions, and the measurement and numerical estimation of hull deflection induced bearing offset changes as well as a way of taking into account these bearing offsets changes.
We evaluated the acute toxicity values (96-h LC50) of the antifoulants copper pyrithione (CuPT) and zinc pyrithione (ZnPT) on a teleost, red sea bream, and a crustacean, toy shrimp. The 96-h LC50s were ranging from 2.5 μg/L to 120 μg/L. The joint toxicity tests of the pyrithiones with Cu using toy shrimp revealed that, in the ZnPT and Cu mixture, conversion of ZnPT to the more toxic CuPT occurred. The early life-stage toxicity test was also conducted for CUPT using a teleost, mummichog, and the result showed that the no observed effect concentration and the lowest observed effect concentration were 0.06 μg/L and 0.22 μg/L, respectively. Additionally, morphological abnormality such as vertebral deformity and tumor formation in lateral muscle were found to be induced by the long-term exposure to CuPT.
The handling liquid for tankers varies widely from low viscosity to high viscosity liquid. Recently, even VLCC starts handling high viscosity liquid. Since the heating device is not equipped to the cargo tank of VLCC, it is quite important to examine whether it is possible to discharge at the unloading port even though the viscosity at loading port was not high by heating. And cargo oil pump and ballast pump require a lot of valve manipulation during unloading and de-ballasting and there is a case of water hammer due to wrong manipulation and pump becomes inoperative. As a recent trend, it is occurring on ballast pump. There is a case of abnormal temperature rise of pump bearing occurs depending on the unloading condition. This is introducing cautions for these matters.
Ships have many advantages in loading capacities compared with vehicles. If the amount of NOx can be reduced by some way, ships can be equipped with oxygen permeable membranes as an oxygen generator that has recently shown a remarkable improvement in the performance of producing more oxygen for the purpose of PM (Particulate Matter) reduction. Therefore, the objective of this study is to examine the effect of oxygen addition on exhaust gas emissions for marine diesel engines. In the experiment oxygen was added to the air suction pipe of a pre-combustion chamber type diesel engine. Then oxygen was added to the exhaust gas pipe before DPF (Diesel Particulate Filter) . The results were as follows: (1) Oxygen addition to the air suction pipe of a pre-combustion chamber type diesel engine decreases both ISF (Insoluble Organic Fraction) and SOF (Soluble Organic Fraction) . Oxygen addition works very well especially at all loads for reduction of ISF with an increase of 2% in oxygen concentration. (2) Although oxygen addition to the air suction pipe of a pre-combustion chamber type diesel engine increases NOx emission. The NOx emission of a pre-combustion chamber type diesel engine is not so much as that of a direct injection type engine. The increase of NOx emission is saturated with further increasing engine load. (3) DPF was effective even in an ordinary type engine that has mechanical fuel injection system and no supercharger. The reduction rate was superior in ISF compared to SOF. (4) Oxygen addition before DPF has almost no effect on PM reduction.
The efficient management of Marine diesel oil on board stands to gain from knowing the properties of the fungi which have an ability to grow in there. A fungus, which was isolated from the sludge trapped on the element in a strainer for Marine diesel oil, was able to grow in Marine diesel oil alone as well as in the chemically defined medium (CDM), pH 5.6 - 5.8, containing 0.1% glucose, 0.1% ammonium sulfate, and 0.1% potassium dihydrogenphosphate. When the isolate was grown in low oxygen concentrations of 0.5 -1.0% (vol/vol), the growth was repressed strongly in the eutrophic growth medium. In Marine diesel oil, however, the growth repression was not observed in the same oxygen concentrations described above in comparison with that in the aerobic condition. The growth in low oxygen condition seems to be limited by the quantity of the isolate in the medium. The isolate utilized n-tridecane and n-tetradecane as carbon and energy sources in CDM when glucose was replaced by these compounds. The reduction of n-tridecane and n-tetradecane in the CDM was found to be 98.8% and 92.3%, respectively, after 40 days of aerobic incubation, indicating that the isolate can utilize n-paraffms in Marine diesel oils.
Fuel injection pressure of diesel engines has been increased to improve engine performance and to reduce emission year by year. The higher injection pressure causes a cavitation and leads to erosion in the nozzle hole. Deformation of nozzle hole may result deterioration in engine performance, especially when using heavy fuel oil. It is noted that rounding-offof nozzle hole inlet proves to be effective to maintain the nozzle hole shape and the injection characteristics. In the present paper, from a fundamental viewpoint, measurement of ignition delays of diesel sprays from single hole injection nozzles with and without rounding-off hole inlet were conducted in a high-pressure combustion chamber. Further, fuel flow patterns in the nozzle hole were numerically simulated by three dimensional highly precision nozzle flow model. When ambient pressure and fuel injection quantity are relatively low, sprays from nozzle without rounding-off hole inlet do not ignite at low ambient temperature. On the other hand, there is no difference in ignition delay under high ambient temperature. In cases where an ambient pressure is high enough and a large amount of fuel is injected, ignition delays of nozzle with rounding-off and without rounding-off show almost the same values even at low ambient temperature. The computed results of numerical simulations show that cavitation level decreases significantly for all cases of rounding-off nozzles.
Higher output and compactness is becoming the norm for low speed diesel engines. The gripping torque of shrink-fit on semi-build up crankshaft can be raised by taking advantage of its high yield point in new cast steel “Throw Grade 5”. Instead, large oversized shrink-fit might induce higher residual stress in the pin fillet or overheating might cause decrease in the cold rolling effect in the pin fillet for short stroke crankshaft. In this paper, a shrink-fit test of the actual crankthrow was carried out for a large oversized shrink-fit. It was accomplished without any decrease of the cold rolling effect in pin fillet. Finally, in order to confirm to safety stress analysis on the crankshaft of a large engine with Throw Grade 5 was made taking the residual stress due to shrink-fit and cold rolling into account.
The high stress into the rolling bearing are locally generated because of the high oil pressure concentrating on a small area under EHL condition. As the result, the failure of rolling bearing might happen if the generated stress is beyond the strength of the material. Therefore it is important to take the stress distribution of rolling bearing into consideration for the efficient design of rolling bearing. Furthermore, it is also important to estimate the oil film thickness as well as stress as the metal-metal contact between the sliding pairs is directly related to the failure of the rolling bearing. In this paper, stress distribution of rolling bearing and oil film thickness are numerically analyzed in a point contact under EHL condition, and the optimum design for rolling bearing was obtained from the result. As a result, it is preferable to give the smaller value of equivalent radius of curvature and the larger value of rotating speed of ball.