Although a long time has passed since alarm bells first sounded a warning of a tendency toward low quality of marine fuel oil, there have been no signs at all of improvement. The low quality of marine fuel oil and mixing with foreign substances leads to serious problems with marine engines. We therefore decided to report our experience on the issue of marine fuel oil quality from the point of view of a ship operating company. Moreover, we report on the correspondence of recent regulations concerning prevention of air pollution by ships and low sulphur fuel oil.
Environmental protection is a global issue: every port, especially those on the west coast of the U.S.A., is required to satisfy stringent environmental regulations. As the ultimate environmental protection solution, the AMP system is increasingly selected by many seaports and ships. This article provides an overview of the background leading to AMP and the current situation of seaports, and the AMP system of NYK ATLAS and some future ideas for AMP are also introduced.
Globe valves are usually used in constant direction. However, globe valves are sometimes used for the reverse flow recently, and then we investigated the loss pressure coefficient on reverse flow and direct flow. As a result, we got the techniques to reduce the pressure loss. And we evaluated the performance of globe valves with designed valve delivery by numerical analyses. The conclusions can be summarized as follows: (1) Loss coefficient of globe valve is remarkably reduced from 6.02 to 4.90 by redesigning the valve delivery. (2) However, the redesigned valve suction does not have such effects.
A bolt heater is frequently used to tighten large bolts that cannot be clamped by any other method. Although the tightening process inherently requires a fair amount of working hours, a bolt heater is less expensive than other tightening tools and can be applied to a tightening operation in a narrow space. This paper proposes a basic method to evaluate the tightening process with a bolt heater, aiming at broader use for middle-sized bolts. A one-dimensional finite difference method was applied to analyze the heating process by which bolt elongation was calculated for a specified heating period. An equation relating bolt elongation to axial bolt force is also proposed; the effects of contact stiffness due to surface roughness are incorporated for better estimation of the axial bolt force. The effectiveness of the basic method proposed here was demonstrated by experiments.
The combustion characteristics (ignition delay, combustion period, and rate of maximum heat release position) of marine heavy fuel oil are affected by many factors, including density, carbon residue, asphaltene content, aromaticity, carbon/hydrogen (C/H) ratio, paraffinic carbon, and others. In investigating the causes on operational problems of marine diesel engines, it is very important to consider what properties we should examine to determine whether the main causes of the problems are related to the fuel oil in use. There might be a threshold of poor fuel oil quality that is related to ignition delay, combustion period, and position of maximum heat release rate. We studied these topics using a constant-volume combustion test apparatus (called FIA 100), and reached the following conclusions: 1. Percentage of paraffinic carbon (%CP) and C/H mass ratio are closely correlated with the combustion characteristics of marine fuel oil. 2. Density has some correlation with combustion characteristics. 3. Carbon residue and asphaltene content in fuel oil show no correlation with ignition delay, but have some correlation with combustion period. 4. There is practically no correlation between sulfur content and combustion characteristics. 5. There is no correlation between oil viscosity and combustion characteristics. 6. Tentative threshold values of C/H mass ratio=8.3 minimum and paraffinic carbon=51 % m/m maximum in marine heavy fuel oil combustion characteristics can be set for fuel oils of poor quality.