Marine Engineering Progress in 1997
Viscosity： The Dumb-Bell blend using the bright stock is avoided, and the base oil of SAE40 class excellent in thermal stability and oxidation stability is used.
TBN： TBN of the scavenging drain is around 40 (by the perchloric acid method), and is sufficient to neutralize sulfuric acid if the cylinder oil is adhered to the liner surface, but the corrosion wear actually takes place.
The inactive reactivity of the cylinder oil additive under the atmosphere in the cylinder during engine operation may be one of the causes. It is desired in future to develop the product having an excellent acid neutralization reactivity under the actual operating condition.
* System Oil
Recently, the increase in the viscosity of the used system oil in the crosshead engine and increase in TBN are remarkable. These are exclusively attributable to recycling of the stuffing drain. Though these items look effective from the aspect of effective use of the resources and the economy in a short range, they are not necessarily effective or economical from the long-range view point.
Disadvantages of highly viscous used oil (not less than SAE40 level)
1) Deviation from SAE30 recommended from engine manufacturers
2) Reduction of the piston cooling effect/increase in carbon deposit
3) Reduction in mechanical efficiency of engine (increase in fuel consumption)
4) Reduction of efficiency of purifier and increase in heating cost of lubricating oil
5) Increase in power consumption of LO pump and purifier pump
Disadvantages of high TBN used oil
1) Poor water separability
2) Difficulty in removing fine contaminants
To avoid losses or risks of engine damages caused by the above-mentioned disadvantages, the drain quantity should be reduced by improving the function of the stuffing box, and re-use should be avoided. Without correct understanding of the actual conditions (degree of oxidation, oxidation stability, thermal stability etc.), the viscosity adjustment of the system oil with the low viscosity oil should be avoided. [Akira TOMITA]
10. Nuclear Ships
10.1 Research and Development by Japan Atomic Energy Research Institute (JAERI)
10.1.1 Nuclear Powered Ship "Mutsu"
The nuclear powered ship "Mutsu" completed the experiments, and overhauled in Sekinehama Mooring Port based on the "Basic plan on the studies necessary for the research and development of nuclear ship by JAERI" stipulated by the Prime Minister and the Minister of Transport on 31st March, 1985. The hull of "Mutsu" after overhaul was delivered from JAERI to the Ocean Science and Technology Center so as to be reborn as the largest sized oceanographic observation ship in the world. The remodeling works have been performed in about 2 years, and the remodeled ship as the oceanographic research ship "Mirai" was engaged in the fall of 1997. Sekinehama Port which used to be fixed port for "Mutsu" is also used as the mother port of "Mirai", and the service station to perform the servicing of oceanographic observation buoys to be mounted on board "Mirai" and the building for the analysis to process the observed data are under construction.
10.1.2 Studies for improvement of Marine Reactor
JAERI has advanced the research and development to the improved marine reactor aiming at realization of the future marine reactor together with the research and development by "Mutsu". In the case of the marine reactor, the requirements for the output, the load conditions, and the automation of the operation are different depending on the kind of ship to be used, and the research and development of two kinds of improved marine reactors, i.e., a large marine reactor MRX (Marine Reactor X) and a deep-sea reactor DRX (Deep-sea Reactor X) have been advanced for the installation onboard an ice-breaking observation ship and a deep-sea scientific research ship which are expected to be realized soon.
The conceptual design has already been established on MRX and DRX, and the development of the element technology such as the fundamental test or the like on the passive safety technology, and the development of the element equipment such as the reactor containment built-in type control rod driving device are advanced in parallel. Consideration has been given to how to advance the design and studies on the engineering level including demonstration of the establishment of the conception, acquisition of the thermal hydrostatic data necessary for developing the detailed design, demonstration of the reliability of the new concept and the operational and maintenance performance.
The MRX is the marine reactor to simultaneously achieve the high safety, miniaturization and weight reduction of the system by employing the integral type PWR, the reactor built-in type control rod driving device, the water-filled type containment, and the decay heat removing system by the natural circulation.
