The dominant factors that control the performances of thermally sprayed coatings are usually physical, chemical, mechanical, and electrical and so on. However, the actual performances of thermally sprayed coatings in industrial fields have not been always determined by these fundamental factors. The reason why the difference occurs is the existence of interaction between sprayed coating and the environment where the coatings are exposed and contacted. The performance of sprayed coatings tends to be influenced by the environment. Thermal spraying modification and its interaction with the environment are reviewed, and the supporting component technology employed is discussed.
IHI has developed the revolutionary coating and cladding technology, named MSCoating®, which can stably built up the functional coating and cladding, and is expected to replace for the plating, welding and plasma spraying. Fundamental tests for application to aero-engines were carried out and MSCoating® has shown the better performance than the existing methods. Many functional capabilities to increase the efficiency of the aero-engines were developed: the anti-wear coating, abrasive coating, and the overlay coating. Further applications not only for aero-engine field but also for a wide variety of fields such as the automobile, the medical field are expected.
To develop thermal spray coatings with corrosion protection and anti-fouling properties, aluminum-copper alloy powders, aluminum-copper blend powders, aluminum-zinc blend powders and a zinc powder are flame sprayed onto a steel substrate and the coatings are immersed in the sea and regularly monitored. Some of the substrates are treated with an aluminum under-coat prior to the spraying of the above-mentioned coatings. The aluminum-copper alloy coatings have poor anti-fouling properties, and the substrate starts to rust after a few months’ immersion in the sea. Although the anti-fouling properties of the aluminum-copper blend coating is improved with increasing copper content, rusting of the steel substrate occurs on the coating with high copper content. The zinc coatings and the aluminum-zinc blend coatings with high zinc content possess both corrosion protection and anti-fouling properties. It was found that the zinc phase in the aluminum-zinc blend coatings preferentially react with the sea water and the content of the metallic zinc phase in the coatings decreases with the immersion time of the coatings in the sea. The aluminum under-coat has little influence on the anti-fouling properties of the aluminum-copper blend coatings and the aluminum-zinc blend coatings, while the formation of the white rust on the coatings is enhanced.
Tokyo Keiki BNWAS WAS-1000 satisfies BNWAS performance standards of IMO Resolution MSC.128(75). The functions are watch-monitoring, providing emergency call and transferring alarms of the external equipment such as TCS (track control system) and INS (integrated navigation system). The system informs VDR (voyage data recorder) and INS of the transition state of watch-monitoring indication and alarm, and outputs BNWAS failure information to VDR and BAMS (bridge alert management system). In summary, this system keeps on watching providing officer on watch with attention step by step, and emergency call and transferring external system’s alarms are available to contribute to the safe navigation.
The environmental preservation and energy conservation measures of marine engines are urgent concerns that need to be addressed. NABTESCO contributes to address these concerns by applying fluid control technology which it has developed in recent years to the electric control of marine diesel engines. ★ This technical paper describes the development of an intelligent hydraulic control valve intended for the fuel injection control of the unit pump system. The development concept was to create a high value product with the superior reliability of NABTESCO’s hydraulic control valves using simulation technology with particular emphasis at the early stages of development.
From the viewpoints of limited fuel oil resources and the problem of global warming, possible alternatives to fossil oil have been widely studied in recent years. Jatropha curcas oil is one of the vegetable oils considered as possible alternatives to fossil fuel. It is effective in reducing CO2 emissions with its carbon-neutral characteristic, and it does not contribute to the problem of increasing food prices because its seeds are poisonous and are thus inedible. This study aims to clarify whether water emulsification can improve the combustion characteristics of Jatropha curcas oil. The experiments were conducted with water-to-Jatropha curcas oil ratios of 5%, 10%, 15%, and 20% by weight, and combustion analysis was carried out. The test engine used was a 4-stroke pre-combustion chamber type diesel engine which can generally run on poor quality fuels. Combustion pressure and fuel injection pressure as well as exhaust gas emissions were measured. It was shown that water emulsification resulted in the improvement of thermal efficiency and the reduction of NOx emissions and carbon deposits.
A new type of lube oil cleaning system was successfully developed for semi-permanent use of oil by always keeping oil clean with no oil change and no waste oil. This system has been put into practical use in many marine diesel engines and in some other fields. Also, the possibility of semi-permanent use of engines themselves was expected based on the field data. A ship test for 7 years has verified the expected semi-permanent use of engines with almost no wear and constant thermal efficiency during the test. In this paper, the characteristics of the oil cleaning system and the results of the test are presented.
The cyclone separator has been used for the separation of particles or dust in a gas or liquid stream. Generally, high separation efficiency can be obtained at the high centrifugal region with a high nozzle velocity when the density of separated material is much larger than that of the working fluid. By using a special eddy breaker in the separation cone described in a previous study, high separation efficiency could be obtained even when the centrifugal force was low and the separated particle density was nearly equal to that of the working fluid. In the present study, the effectiveness of the eddy breaker was investigated for different liquid cyclone separator sizes.
Collection of low resistive particulate matter (PM) generated from marine engines or from diesel generators with conventional electrostatic precipitators (ESP) has been known to be difficult. Therefore, a double cylinder type ESP is suggested to remove diesel exhaust particles. The present major focus regarding double cylinder type ESPs is to study the numerical simulation for the aerodynamics behavior and the re-entrained particle motion. The ESP consists of three electrodes, which are the high voltage saw electrode, grounded hole punched electrode and grounded electrode. Numerical simulation results show that re-entrainment of diesel particles can be suppressed with this double cylinder ESP configuration.
Selective catalytic reduction (SCR) is an effective technique to reduce nitrogen oxides (NOx) from diesel engine emissions. The droplet lifetime of the injected urea water is important for the control of DeNOx performance. In this study, the influence of gas temperature and droplet diameter on the evaporation of droplet urea water and the effect of reducing agent were investigated using a simple reaction model for predicting the deactivation of DeNOx performance. This numerical model gives the following predictions: To promote droplet evaporation and to minimize the dependence on temperature, it is necessary to make the liquid drop diameter smaller. Moreover, urea and NH3 as reducing agents produced similar NO conversion efficiencies and similar deactivation characteristics.
Selective catalytic reduction (SCR) is an effective technique to reduce nitrogen oxides (NOx) from diesel engine emissions. In this study, the influence of DeNOx performance, deactivation characteristics and the ammonium bisulfate deposition on the catalyst surface by the homogeneity of the reducing agent were investigated. The results indicate that the low NOx conversion due to homogeneity deterioration is improved not by the high temperature and long reaction time but by the small NH3/NO ratio. The degradation of homogeneity inhibits the deactivation of DeNOx performance. On the other hand, it increases the NH3 slip. The ammonium bisulfate deposition depends on the local NH3/NO ratio, and it reaches a maximum value at the NH3/NO ratio of 1.0∼1.2 under a catalyst temperature condition of 250°C.