Status of research and development of advanced coal-utilized power generation technologies such as pulverized coal combustion and integrated coal gasification combined cycle (IGCC) power generation systems were reviewed and discussed in this paper. It was confirmed in the pulverized coal combustion system that the advanced low NOx combustion technology with a new type low NOx burner effectively reduced NOx emission and moisture evaporated from low-rank coal significantly affected combustion characteristics of bituminous coal blended with the low-rank coal. It was also revealed in the IGCC system that simultaneous evaluation of gasification efficiency and molten slag behavior was essentially important to maintain stable operation of the system. Throughout the research activities, it is found that a numerical simulation was a key technology to assess and optimize design and operation of major components such as coal combustion boiler and coal gasifier in the systems.
Seafloor Massive Sulfides (SMSs), which were formed by deposition of precipitates from hydrothermal fluids vented from seafloor, are one of unconventional mineral resources beneath deep seafloors in the Exclusive Economic Zone (EEZ) of Japan. The authors have proposed the concept of Seafloor Mineral Processing, where useful minerals contained in SMS ores are separated from feed ores on deep seafloor to be lifted while remaining gangue is disposed on seafloor in appropriate ways. To apply column flotation, which is usually used for mineral processing on land, for seafloor mineral processing, model experiments of column flotation on deep seafloor were carried out at high pressures up to 10MPa using a large-scale high pressure vessel. In the experiments, fine bubbles suitable to flotation were generated in the flotation column at the pressures, and overflow of froth from the flotation column was observed. The content of metallic elements such as copper and zinc in the concentrates obtained from flotation at 1MPa was higher than that in the feed ores while that of silicon and calcium, which are mainly assigned to gangue, was lower than that in the feed ores. These results suggest that column flotation would be applicable for seafloor mineral processing.
When a suitable site has been found and established, tidal power and ocean current power is more predictable than wind and fluctuates less drastically than solar. It's a reliable producer of electricity. Tidal energy and ocean current energy are produced through the use of generators. These large underwater turbines are placed in areas with high tidal movements and ocean current, and are designed to capture the kinetic motion of the ebbing and surging of ocean tides in order to produce electricity. Tidal power and ocean current power have great potential for future power and electricity generation because of the massive size of the oceans. These articles explore the potential energy of tidal and ocean current power technologies.
A variety of technical methods with gas (air or oxygen) release have been used to purify water in eutrophic lakes and reservoirs. They are roughly classified into two types: 1)destratification and circulation by air bullets or bubble plumes, and 2)direct aeration in a bottom layer by micro-bubbles. Their effectiveness has been verified in many dam reservoirs, however, their further improvement and development will be needed. In this paper, a bubble plume system through the use of solar energy was presented according to a previous study, and its development was discussed including the potential for a green technology.
Detailed numerical simulations of Diesel liquid jet sprays have been conducted to elucidate the liquid atomization mechanisms. The obtained flow field is very complicated, but the spray behavior can be understood physically. The jet head formation leads to vortex shedding and subsequent atomization from the head edge. The liquid core surface is also unstable due to gas boundary layer instability and atomization also occurs from here. The final process of droplet generation from a ligament is basically the same as the past research results, and can be explained by the capillary wave destabilization. Such findings can be used for droplet modeling for practical-scale simulations.