High concentration of aqueous glycerine was decomposed using a direct current （DC） plasma torch at atmospheric pressure. The torch can generate the plasma with water as the plasma-supporting gas in the absence of an...High concentration of aqueous glycerine was decomposed using a direct current （DC） plasma torch at atmospheric pressure. The torch can generate the plasma with water as the plasma-supporting gas in the absence of any additionM gas supply system and cooling devices. The results indicated that 5 mol% glycerine was completely decomposed by water plasmas at arc powers of 0.55~1.05 kW. The major products in the effluent gas were H2 （68.9%~71.1%）, CO2 （18.9%~23.0%）, and CO （0.2%~0.6%）. However, trace levels of formic acid （HCOOH） and formaldehyde （HCHO） were observed in the liquid effluent. The results indicated that the water plasma waste treatment process is capable of being an alternative green technology for organic waste decomposition.展开更多
The multifunctionality and the advantages of thermal plasma for the fast inactivation of viable cells and degradation of organic compounds dissolved in waste water are presented.A complete bacterial inactivation proce...The multifunctionality and the advantages of thermal plasma for the fast inactivation of viable cells and degradation of organic compounds dissolved in waste water are presented.A complete bacterial inactivation process was observed and studied using a thermal plasma treatment source with very short application times,in particular for Staphylococcus aureus bundle spore survival.The survival curves and analyses of the experimental data of the initial and final densities of S.aureus bacteria show a dramatic inhibitory effect of the plasma discharge on the residual bacteria survival ratio.As the exposure time increased,the inactivation process rate increased for direct exposure more than it did for indirect exposure.The evaluation of direct and indirect exposure was based on the analysis of the ultraviolet spectrum from the absorbance spectra of the organic compound dye called benzene sulfonate（C（16）H（11）N2Na O4S）and of viable cells called S.aureus.Organic compounds were degraded and viable cells were killed in a short time by thermal plasma.Moreover,analyses of total carbon,total organic carbon,and total inorganic carbon showed a fast decrease in organically bound carbon,however,this was not as fast as the absorbance spectra revealed by the exposure time increasing more for direct exposure than indirect exposure.After 100 s of exposure to the organic compound dye the removal had a maximun of 40%for samples with indirect exposure to the plasma and a maximum of 90%for samples with the direct exposure.For both samples,where some organic contaminants still remained in treated water,four electrolytes（KCl,Na Cl,Na2SO4,and CH3COONa）were added to be effective for complete sterilization,reaching a purity of 100%.A proposal is made for an optimized thermal plasma water purification system（TPWPS）to improve fast inactivation of microbes and the degradation of organic compounds dissolved in water（especially for direct exposure rather than indirect exposure）using a hybrid plasma torch with an electrical power of 125 kW（500 V–250 A）producing a high-temperature（10 000 K–19 000 K）plasma jet with a maximum gas consumption of 28 mg s^-1.展开更多
Decomposition of carbon tetrachloride was studied theoretically in the most commonly used thermal plasma atmosphere such as H2, N2, O2 and water steam. A code developed by the National Aeronautics and Space Administra...Decomposition of carbon tetrachloride was studied theoretically in the most commonly used thermal plasma atmosphere such as H2, N2, O2 and water steam. A code developed by the National Aeronautics and Space Administration （NASA） was adopted to calculate the chemical equilibrium distribution and energy consumption of the decomposition of CC;4 in the H2, N2, O2 and water steam atmosphere thermal plasma respectively, with a temperature range of 500 K to 5000 K. In the neutral condition （H2, N2, atmosphere） formation of solid carbon was observed and in the oxygen-atmosphere （O2 and water steam） solid carbon formation disappeared through controlling the ratio of C/O. This indicates that the formation of polycyclic aromatic hydrocarbons （PAHs） is impossible theoretically. The energy consumption in the N2 atmosphere was much higher than that in the H2, O2 and water steam atmosphere at 1500 K.展开更多
CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a th...CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is limited.In this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition environment.The decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium calculations.The chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical analysis.The injection position and angle of the CF4 were controlled in order to enhance the decomposition rate.The vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma flame.In addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped reactor.As a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.展开更多
A water plasma was generated by DC arc discharge with a hafnium embedded rodtype cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The...A water plasma was generated by DC arc discharge with a hafnium embedded rodtype cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.展开更多
Plasma technology has some shortcomings, such as higher energy consumption and byproducts produced in the reaction process. However non-thermal plasma associated with catalyst can resolve these problems. So this kind ...Plasma technology has some shortcomings, such as higher energy consumption and byproducts produced in the reaction process. However non-thermal plasma associated with catalyst can resolve these problems. So this kind of technology was paid more and more attention to treat waste gas. In this paper, we make use of this technology to decompose toluene under different electric field and packed materials. At the same time, the mechanism of toluene decomposition using plasma and catalyst is discussed. The experimental results show toluene decomposition increases with electric field strength increasing and flow velocity and initial concentration decreasing. There are four conditions in plasma: without packed materials (1);with packed materials (2);with BaTiO3 in the surfaces of packed materials (3);and with nanometer Ba0.8Sr0.2Zr0.1Ti0.9O3 (4). Toluene decomposition represents a obvious trend, that is, η(4) > η(3) > η(2) > η(1). The best decomposition efficiency of toluene arrives at 95%.展开更多
Laser paint removal in a water environment does not diffuse ablation pollution products into air.Characteristics of water,such as high specific heat and heat flux,generate different effects of the laser paint removal ...Laser paint removal in a water environment does not diffuse ablation pollution products into air.Characteristics of water,such as high specific heat and heat flux,generate different effects of the laser paint removal than in an air environment.In this study,the effects of air and water environments on the mechanism and effect of laser paint removal are analyzed and compared experimentally and theoretically.In air,thermodynamic ablation causes removal of paint,whereas in water,stress coupled with plasma shock waves cause tear and splash removal of paint layers after fracture and damage.Fracture and pressure thresholds of the paint and substrate,respectively,indicate the optimum energy density range for laser paint removal in water,providing a reference for engineering applications.展开更多
基金supported by a Grant-in-Aid for Scientific Research (20310038) from the Ministry of Education, Culture, Sports, Science and Technology of Japan
文摘High concentration of aqueous glycerine was decomposed using a direct current （DC） plasma torch at atmospheric pressure. The torch can generate the plasma with water as the plasma-supporting gas in the absence of any additionM gas supply system and cooling devices. The results indicated that 5 mol% glycerine was completely decomposed by water plasmas at arc powers of 0.55~1.05 kW. The major products in the effluent gas were H2 （68.9%~71.1%）, CO2 （18.9%~23.0%）, and CO （0.2%~0.6%）. However, trace levels of formic acid （HCOOH） and formaldehyde （HCHO） were observed in the liquid effluent. The results indicated that the water plasma waste treatment process is capable of being an alternative green technology for organic waste decomposition.
基金financial support from MEPhI in the framework of the Russian Academic Excellence Project
文摘The multifunctionality and the advantages of thermal plasma for the fast inactivation of viable cells and degradation of organic compounds dissolved in waste water are presented.A complete bacterial inactivation process was observed and studied using a thermal plasma treatment source with very short application times,in particular for Staphylococcus aureus bundle spore survival.The survival curves and analyses of the experimental data of the initial and final densities of S.aureus bacteria show a dramatic inhibitory effect of the plasma discharge on the residual bacteria survival ratio.As the exposure time increased,the inactivation process rate increased for direct exposure more than it did for indirect exposure.The evaluation of direct and indirect exposure was based on the analysis of the ultraviolet spectrum from the absorbance spectra of the organic compound dye called benzene sulfonate（C（16）H（11）N2Na O4S）and of viable cells called S.aureus.Organic compounds were degraded and viable cells were killed in a short time by thermal plasma.Moreover,analyses of total carbon,total organic carbon,and total inorganic carbon showed a fast decrease in organically bound carbon,however,this was not as fast as the absorbance spectra revealed by the exposure time increasing more for direct exposure than indirect exposure.After 100 s of exposure to the organic compound dye the removal had a maximun of 40%for samples with indirect exposure to the plasma and a maximum of 90%for samples with the direct exposure.For both samples,where some organic contaminants still remained in treated water,four electrolytes（KCl,Na Cl,Na2SO4,and CH3COONa）were added to be effective for complete sterilization,reaching a purity of 100%.A proposal is made for an optimized thermal plasma water purification system（TPWPS）to improve fast inactivation of microbes and the degradation of organic compounds dissolved in water（especially for direct exposure rather than indirect exposure）using a hybrid plasma torch with an electrical power of 125 kW（500 V–250 A）producing a high-temperature（10 000 K–19 000 K）plasma jet with a maximum gas consumption of 28 mg s^-1.
文摘Decomposition of carbon tetrachloride was studied theoretically in the most commonly used thermal plasma atmosphere such as H2, N2, O2 and water steam. A code developed by the National Aeronautics and Space Administration （NASA） was adopted to calculate the chemical equilibrium distribution and energy consumption of the decomposition of CC;4 in the H2, N2, O2 and water steam atmosphere thermal plasma respectively, with a temperature range of 500 K to 5000 K. In the neutral condition （H2, N2, atmosphere） formation of solid carbon was observed and in the oxygen-atmosphere （O2 and water steam） solid carbon formation disappeared through controlling the ratio of C/O. This indicates that the formation of polycyclic aromatic hydrocarbons （PAHs） is impossible theoretically. The energy consumption in the N2 atmosphere was much higher than that in the H2, O2 and water steam atmosphere at 1500 K.
文摘CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is limited.In this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition environment.The decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium calculations.The chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical analysis.The injection position and angle of the CF4 were controlled in order to enhance the decomposition rate.The vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma flame.In addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped reactor.As a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.
文摘A water plasma was generated by DC arc discharge with a hafnium embedded rodtype cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.
文摘Plasma technology has some shortcomings, such as higher energy consumption and byproducts produced in the reaction process. However non-thermal plasma associated with catalyst can resolve these problems. So this kind of technology was paid more and more attention to treat waste gas. In this paper, we make use of this technology to decompose toluene under different electric field and packed materials. At the same time, the mechanism of toluene decomposition using plasma and catalyst is discussed. The experimental results show toluene decomposition increases with electric field strength increasing and flow velocity and initial concentration decreasing. There are four conditions in plasma: without packed materials (1);with packed materials (2);with BaTiO3 in the surfaces of packed materials (3);and with nanometer Ba0.8Sr0.2Zr0.1Ti0.9O3 (4). Toluene decomposition represents a obvious trend, that is, η(4) > η(3) > η(2) > η(1). The best decomposition efficiency of toluene arrives at 95%.
基金supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics NSAF(No.U2030108)Sichuan Science and Technology Program(No.2021YFSY0027)the National Natural Science Foundation of China(No.U2004162)。
文摘Laser paint removal in a water environment does not diffuse ablation pollution products into air.Characteristics of water,such as high specific heat and heat flux,generate different effects of the laser paint removal than in an air environment.In this study,the effects of air and water environments on the mechanism and effect of laser paint removal are analyzed and compared experimentally and theoretically.In air,thermodynamic ablation causes removal of paint,whereas in water,stress coupled with plasma shock waves cause tear and splash removal of paint layers after fracture and damage.Fracture and pressure thresholds of the paint and substrate,respectively,indicate the optimum energy density range for laser paint removal in water,providing a reference for engineering applications.
