• Title, Summary, Keyword: thermal plasma

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THERMAL PLASMA DECOMPOSITION OF FLUORINATED GREENHOUSE GASES

  • Choi, Soo-Seok;Park, Dong-Wha;Watanabe, Takyuki
    • Nuclear Engineering and Technology
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    • v.44 no.1
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    • pp.21-32
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    • 2012
  • Fluorinated compounds mainly used in the semiconductor industry are potent greenhouse gases. Recently, thermal plasma gas scrubbers have been gradually replacing conventional burn-wet type gas scrubbers which are based on the combustion of fossil fuels because high conversion efficiency and control of byproduct generation are achievable in chemically reactive high temperature thermal plasma. Chemical equilibrium composition at high temperature and numerical analysis on a complex thermal flow in the thermal plasma decomposition system are used to predict the process of thermal decomposition of fluorinated gas. In order to increase economic feasibility of the thermal plasma decomposition process, increase of thermal efficiency of the plasma torch and enhancement of gas mixing between the thermal plasma jet and waste gas are discussed. In addition, noble thermal plasma systems to be applied in the thermal plasma gas treatment are introduced in the present paper.

Investigation on The Role of Arc-jet Plasma in Methane Reforming (메탄개질에서의 아크젯 플라즈마의 역할)

  • Hwang, Na-Kyung;Lee, Dae-Hoon;Song, Young-Hoon
    • Journal of the Korean Society of Combustion
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    • v.11 no.3
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    • pp.1-7
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    • 2006
  • A reaction mechanism of methane partial oxidation, which consists of thermal and plasma chemistry reaction pathways, has been investigated using with an arc-jet reactor. The reaction zone of the arc-jet reactor is spatially separated into thermal and non-thermal plasma zone. Methane conversion rates, selectivity of $H_2$ and $C_2$ chemicals in each zone are obtained, which reveals clearly different characteristics of reaction pathways depending on the temperature conditions. The conversion rates obtained in thermal plasma zone is higher than those in non-thermal plasma zone. The selectivity, however, obtained in non-thermal plasma zone is significantly higher than those in thermal plasma zone. Further parametric study on $O_2/C$ ratio, arc length and SED shows that the present process is mainly governed by thermal chemistry pathways.

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Large Scale Treatment of Perfluorocompounds Using a Thermal Plasma Scrubber

  • Han, Sung-Han;Park, Hyun-Woo;Kim, Tae-Hee;Park, Dong-Wha
    • Clean Technology
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    • v.17 no.3
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    • pp.250-258
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    • 2011
  • Thermal plasma has been presented for the decomposition of perfluorocompounds (PFCs) which are extensively used in the semiconductor manufacturing and display industry. We developed pilot-scale equipment to investigate the large scale treatment of PFCs and called it a "thermal plasma scrubber". PFCs such as $CF_4$, $C_2F_6$, $SF_6$, and $NF_3$ used in experiments were diluted with $N_2$. There were two different types of experiment setup related to the water spray direction inside the thermal plasma scrubber. The first type was that the water was sprayed directly into the gas outlet located at the exit of the reaction section. The second type was that the water was sprayed on the wall of the quenching section. More effective decomposition took place when the water was sprayed on the quenching section wall. For $C_2F_6$, $SF_6$, and $NF_3$ the maximum destruction and removal efficiency was nearly 100%, and for $CF_4$ was up to 93%.

Formation of YSZ Coatings Deposited by Suspension Vacuum Plasma Spraying (서스펜션 진공 플라즈마 용사법을 통한 YSZ 코팅의 형성)

  • Yoo, Yeon Woo;Byon, Eungsun
    • Journal of the Korean institute of surface engineering
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    • v.50 no.6
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    • pp.460-464
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    • 2017
  • As increasing thermal efficiency of the gas turbine, the performance improvement of thermal barrier coatings is also becoming important. Ytrria stabilized zirconia(YSZ) is the most popular materials for ceramic top coating because of its low thermal conductivity. In order to enhance the performance of thermal barrier coatings for hot sections in the gas turbine, suspension plasma spraying was developed in order to feed nano-sized powders. YSZ coatings formed by suspension plasma spraying showed better performance than YSZ coatings due to its exclusive microstructure. In this research, two YSZ coatings were deposited by suspension vacuum plasma spraying at 400 mbar and 250 mbar. Microstructures of YSZ coatings were analyzed by scanning electron image(SEM) on each spraying conditions, respectively. Crystalline structure transformation was not detected by X-ray diffraction. Thermal conductivity of suspension vacuum plasma sprayed YSZ coatings were measured by laser flash analysis. Thermal conductivity of suspension vacuum plasma sprayed YSZ coatings containing horizontally oriented nano-sized pores and vertical cracks showed $0.6-1.0W/m{\cdot}K$, similar to thermal conductivity of YSZ coatings formed by atmospheric plasma spraying.

APPLICATION OF RADIO-FREQUENCY (RF) THERMAL PLASMA TO FILM FORMATION

  • Terashima, Kazuo;Yoshida, Toyonobu
    • Journal of the Korean institute of surface engineering
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    • v.29 no.5
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    • pp.357-362
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    • 1996
  • Several applications of radio-frequency (RF) thermal plasma to film formation are reviewed. Three types of injection plasma processing (IPP) technique are first introduced for the deposition of materials. Those are thermal plasma chemical vapor deposition (CVD), plasma flash evaporation, and plasma spraying. Radio-frequency (RF) plasma and hybrid (combination of RF and direct current(DC)) plasma are next introduced as promising thermal plasma sources in the IPP technique. Experimental data for three kinds of processing are demonstrated mainly based on our recent researches of depositions of functional materials, such as high temperature semiconductor SiC and diamond, ionic conductor $ZrO_2-Y_2O_3$ and high critical temperature superconductor $YBa_2Cu_3O_7-x$. Special emphasis is given to thermal plasma flash evaporation, in which nanometer-scaled clusters generated in plasma flame play important roles as nanometer-scaled clusters as deposition species. A novel epitaxial growth mechanism from the "hot" clusters namely "hot cluster epitaxy (HCE)" is proposed.)" is proposed.osed.

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Numerical Analysis on RF (Radio-frequency) Thermal Plasma Synthesis of Nano-sized Ni Metal (고주파 열플라즈마 토치를 이용한 Ni 금속 입자의 나노화 공정에 대한 전산해석 연구)

  • Nam, Jun Seok;Hong, Bong-Guen;Seo, Jun-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.5
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    • pp.401-409
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    • 2013
  • Numerical analysis on RF (Radio-Frequency) thermal plasma treatment of micro-sized Ni metal was carried out to understand the synthesis mechanism of nano-sized Ni powder by RF thermal plasma. For this purpose, the behaviors of Ni metal particles injected into RF plasma torch were investigated according to their diameters ($1{\sim}100{\mu}m$), RF input power (6 ~ 12 kW) and the flow rates of carrier gases (2 and 5 slpm). From the numerical results, it is predicted firstly that the velocities of carrier gases need to be minimized because the strong injection of carrier gas can cool down the central column of RF thermal plasma significantly, which is used as a main path for RF thermal plasma treatment of micro-sized Ni metal. In addition, the residence time of the injected particles in the high temperature region of RF thermal plasma is found to be also reduced in proportion to the flow rate of the carrier gas In spite of these effects of carrier gas velocities, however, calculation results show that a Ni metal particle even with the diameter of $100{\mu}m$ can be completely evaporated at relatively low power level of 10 kW during its flight of RF thermal plasma torch (< 10 ms) due to the relatively low melting point and high thermal conductivity. Based on these observations, nano-sized Ni metal powders are expected to be produced efficiently by a simple treatment of micro-sized Ni metal using RF thermal plasmas.

Study on Corrosion Resistance Performance of Zn Coating Applied by Arc Thermal and Plasma Arc Spray Process in Artificial Ocean Water (인공해양환경에서 Arc Thermal and Plasma Arc Spray 공법이 적용된 Zn 코팅 강재의 내식성능 평가에 관한 연구)

  • Jannat, Adnin Raihana;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.83-84
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    • 2020
  • In present study, we have deposited the Zinc coating using arc thermal spray and plasma arc spray processes onto the steel substrate and durability of the deposited coating was evaluated. The bond adhesion result shows that plasma arc sprayed Zn coating exhibited higher in its value compared to arc thermal spray. SEM shows that Zn coating deposited by plasma arc process is more compact, less porous and adherent compare to arc spray process. The corrosion resistance properties are evaluated in artificial ocean water solution with exposure periods. EIS results show that total impedance at 0.01 Hz of plasma arc sprayed coating is higher than arc thermal spray owing to the compact and less porous morphology. It is concluded that plasma arc sprayed Zn coating is better than arc thermal spray process.

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Non-Thermal Atmospheric-Pressure Plasma Possible Application in Wound Healing

  • Haertel, Beate;von Woedtke, Thomas;Weltmann, Klaus-Dieter;Lindequist, Ulrike
    • Biomolecules & Therapeutics
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    • v.22 no.6
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    • pp.477-490
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    • 2014
  • Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out.

Hydroxyl Radical Species Generated by Non-thermal Direct Plasma Jet and Their Qualitative Evaluation

  • Ghimire, B.;Hong, S.I.;Hong, Y.J.;Choi, E.H.
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.198.2-198.2
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    • 2016
  • Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.

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Non-thermal plasma technology for abatement of pollutant emission from marine diesel engine

  • Panomsuwan, Gasidit;Rujiravanit, Ratana;Ueno, Tomonaga;Saito, Nagahiro
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.10
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    • pp.929-934
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    • 2016
  • Plasma technology has long been regarded as a key essential tool in many industrial and technological sectors. However, the advancement of plasma technology in marine applications has not been fully realized yet. Herein, we present a short overview on the recent trends in utilization of plasma technology for air-pollution treatment in marine diesel exhaust. Four non-thermal plasma system, including electron beam dry scrubber (EBDS), dielectric barrier discharge (DBD), electron beam-microwave (EB-MW) plasma hybrid system, and plasma-catalytic hybrid system, are described with emphasis on their efficiency in removals of $NO_x$ and $SO_x$ gases. Non-thermal plasma has the great potential to be an efficient and environmentally compatible technique in simultaneous removals of $NO_x$ and $SO_x$ gases from the exhaust of marine diesel engine in the future.