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日本語はこちら Takayuki Watanabe Professor Field of study : Plasma Chemistry, Energy Engineering December 4, 2023 Up
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![]() ISPC25 (Kyhoto, Japan) May 21-26, 2023 |
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NEWS
Waste Treatment by Atmospheric Pressure Plasmas can be downloaded from here. |
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1 The subject and aims of research | |||||
Thermal plasmas have simply been used as a high temperature source. This indicates that thermal plasmas may have more capabilities in material processing, especially production of high-quality and high-performance materials, if thermal plasmas are utilized effectively as chemically reactive gases. Therefore we developed the numerical analysis to investigate non-equilibrium characteristics in thermal plasmas. These results can be utilized for the nano-material synthesis as well as waste treatment using thermal plasmas. |
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2 Related recent research topics |
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Modeling of Reactive Plasma Flows The induction thermal plasma approach has been applied for many fields, including treatment of harmful waste materials, recovery of useful material from waste, and production of high-quality and high-performance materials, such as synthesis of nanoparticles, deposition of thin films, and plasma spraying. Induction thermal plasmas offer unique advantages including high enthalpy to enhance reaction kinetics, high chemical reactivity, oxidation and reduction atmospheres in accordance with required chemical reactions, and rapid quenching. These advantages increase the advances and demands in plasma chemistry and plasma processing. |
![]() RF plasma temperature distribution for nanoparticle synthesis. |
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Comparison of temperature distributions obtained from the chemical equilibrium model (CE) and from the chemical non-equilibrium model (CNE) for argon-oxygen induction plasmas. |
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Development of Innovative In-Flight Glass Melting Technology for Energy Conservation We developed innovative in-flight glass melting technology under the support of New Energy and Industrial Technology Development Organization (NEDO) project in Japan from 2005 until 2012. The granulated raw material with small diameter is dispersed in thermal plasmas and the powders contact fully with the plasma and burner flame. The high heat-transfer and temperatures of the plasma will melt the raw material quickly. In addition, the decomposed gas of carbonates is removed during the in-flight treatment to reduce the fining time considerably. Compared with the traditional glass production, the total vitrification time is evaluated only 2-3 h in the same productivity as the fuel-fired melter. A multiphase AC arc was developed for the application of glass melting technology. The large volume discharge produced by a stable multiphase AC arc is preferable to melt the granulated glass materials. The discharge behavior and the high-temperature region of the plasma can be controlled by the electrode configurations. ![]() |
![]() ![]() Multiphase AC arc for material processing. |
![]() Development of new glass melting technology that can rapidly melt atomized and homogenized granular glass materials. ![]() High-quality glass (porosity < 0.01%) were produced from in-flight melted powders. |
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Generation of Water Plasmas under Atmospheric Pressure DC 100%-steam plasma characteristics were investigated for the application of halogenated hydrocarbon decomposition. The developed steam plasma system is a portable light-weight plasma generation system that does not require any gas supply. The system has high energy-efficiency since cooling water is not needed. In addition, a dry process was developed for halogenated hydrocarbon decomposition and simultaneously adsorbing fluorine and bromine with solid alkaline reactants.Water plasma system has been scaled up into a mobile system in a vehicle with direct-current generator. This innovative in-vehicle plasma has great advantage to reduce the risk and cost caused by the transportation of harmful wastes. The developed system has been installed at Helix Co. Ltd., Japan for the waste oil treatment. Applications for the destruction of hazardous and waste materials such as halogenated hydrocarbons by water thermal plasmas were developed. For halogenated hydrocarbon decomposition, key technologies are the stable generation of DC water plasmas and the off-gas treatment after the decomposition of halogenated hydrocarbon. Therefore, DC 100%-steam plasma characteristics were investigated for the application of halogenated hydrocarbon decomposition. The developed water plasma system is a portable light-weight plasma generation system that does not require any gas supply. The system has high energy-efficiency since cooling water is not needed. In addition, a dry process was developed for the off-gas treatment of halogenated hydrocarbon decomposition using solid alkaline reactants. |
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Photographs for water plasma, methanol-water plasma, and ethanol-water
plasma for waste treatments.
![]() In-vehicle water plasma jet. |
![]() ![]() Water plasma torch for waste destruction. |
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Preparation of Functional Nanoparticles by Thermal Plasmas Functional nanoparticles of silicide and boride were prepared by induction
thermal plasmas. Silicide and rare-earth boride are attractive materials
because of their high melting temperature, high electrical conductivity
and low work function. Therefore these nanoparticles would be applied for
electromagnetic shielding, and solar control windows with interaction with
IR and UV light. |
![]() Induction thermal plasma system for nanoparticle synthesis. |
![]() Tetradecahedral Spinel LiMn2O4 were synthesized by RF plasmas for Lithium-ion battery. |
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Waste Treatment by Reactive Thermal Plasmas Attractive thermal plasma processes have been proposed especially for waste
treatment, because engineering advantages such as smaller reactor, lower
capital cost, portability allowing on-site destruction, rapid start-up
and shutdown offer efficient destruction of hazardous and waste materials. |
![]() Thermal plasma jet for waste destruction. ![]() Cobalt doped resins after the plasma treatments. |
![]() Hydrogen generation from waste using thermal plasmas. Water plasma system for CFC destruction. |
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Development of Material Processing by Non-Equilibrium Atmospheric Plasmas Atmospheric pressure plasma has been studied for the application of material
surface cleaning, preparation of surface coating, and modification of polymer
film. In this study, the atmospheric non-thermal plasmas ere applied to
surface cleaning of waste plastic. |
![]() Indium recovery from liquid crystal panel using atmospheric glow discharge. |
![]() Glow discharge of air under atmospheric pressure. ![]() Seed treatment by atmospheric glow discharge. |
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Lunar Resources Utilization Ground-engineering work on experimental missions for lunar resource utilization
has been conducted. The goal of the research program is to conceptually
design an experiment system for unmanned water production on the Moon,
and to define essential technological breakthroughs. |
![]() Oxygen production form lunar regolith. ![]() Experiment of water production from lunar soil simulant. |
![]() Water production system by hydrogen reduction of lunar soil simulant. |
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List of Publications (Plasma Characteristics, Plasma Generations) List of Publications (Plasma Materials Processing) List of Publications (Plasma Waste Treatments, Others) Books, Patents, Projects, Awards |