Induction Plasma Torch Research Articles

Plasmolysis of methane using a high-frequency plasma torch

The possibility of converting methane into hydrogen using a high-frequency induction plasma torch at the atmospheric pressure has been experimentally studied. The dependencies of the degree of methane conversion and the rate of hydrogen production were studied depending on the process conditions. It has been demonstrated that the degree of the methane-to-hydrogen conversion can reach values close to 100%. Keywords: methane plasmolysis, HF plasma torch, hydrogen.

Плазмолиз метана при помощи высокочастотного плазмотрона

The possibility of converting methane into hydrogen using a high-frequency induction plasma torch at atmospheric pressure has been experimentally studied. The dependencies of the degree of methane conversion and the rate of hydrogen production were studied depending on the process conditions. It has been demonstrated that the degree of conversion of methane to hydrogen can reach values close to 100%.

О выборе параметров высокочастотного индукционного плазмотрона и дисперсного потока испаряемых кварцевых частиц

Numerical simulation of the heating and evaporation processes of quartz particles in a technical induction plasma torch of argon plasma was performed in the framework of a two-phase collisionless monodisperse model. The particle supply conditions within a full and partial penetration through the frontal ring-type vortex into discharge zone were determined. The dependences of the evaporation degree and specific energy cost for evaporation on the main operation parameters of the particle processes, primarily the coupled power of plasma torch, as well as the particle size, feed rate and entry angle into the discharge zone were established. The recommendations on the choice of the optimal operation parameters of the plasma torch and the flow parameters of quartz particles were given. It was shown that the technical induction plasma torch with a coupled power of about 5 kW can provide a complete evaporation of the quartz particles with sizes up to 50 – 70 μm and mass flow rate of up to (8 – 10) ‧10-5 kg/s under a specific energy cost at 50 MJ/kg

Effect of Gas Dynamic Conditions in Plasma Reactor on Efficiency of Boron and Silicon Synthesis in Inductively Coupled Argon–Hydrogen Plasma

A thermal/gas dynamic model of the plasma-assisted method for producing boron and silicon carbides is proposed. The turbulent flow of a mixture of ideal viscous compressible gases is considered taking into account inductive heating and the influence of the electromagnetic field strength on the plasma motion. The composition of the conversion products is determined in accordance with the results of thermodynamic calculations, while taking into account the influence of the main synthesis products on the temperature field and gas dynamic flow in the reactor. The distribution of powder particles of the desired synthesis products in the stream is described by the diffusion mechanism. The possibilities of synthesis of boron and silicon carbides from their fluorides in a radiofrequency induction plasma torch with vortex flow stabilization have been explored.

Reduction of Boron Trichloride in Atmospheric-Pressure Argon–Hydrogen Radiofrequency Induction Plasma

The main operating modes of a radiofrequency induction plasma torch with a vortex stabilization of the atmospheric-pressure gas discharge at have been studied in an argon-hydrogen mixture in the range of Ar/H2 = 12–4. The dependences of the electron temperature Te and number density ne on the Ar/H2 ratio have been experimentally studied. It has been found that the electron temperature and concentration in pure argon plasma are 0.88 eV and 7.6 × 1014 cm−3, respectively. When the Ar/H2 ratio decreases, the electron temperature decreases to 0.42 eV, and the electron number density is 8 × 1012 cm−3. The calorimetric method used to estimate the gas temperature Tg, has given a value of 2500 K. The process of BCl3 reduction with hydrogen has been studied at the implemented operating modes of the induction plasma torch. The main products of the reduction of boron trichloride are a polycrystalline boron powder and dichloroborane. The morphology of boron and its phase composition and impurities have been studied. The average particle size of the boron powder is 200 nm.

INFLUENCE OF MODE AND GEOMETRIC CHRATERISTICS ON HIGHT-FREQUENCY INDUCTIVE PLASMA TORCH WITH REVERSE VORTEX FLOW

The analysis of aerodynamic and heat structure of flow in high-frequency inductive plasma torch has been carried out. The range of plasma torch power is measured in dozens of kilowatts. The numerical simulation methods of the turbulent flow in the plasma torch affected by high frequency electromagnetic field without considering the chemical kinetics are used during the research. The data of temperature field and induced current density in the plasma torch depending on current amperage and frequency are obtained. Also, these data are obtained depending on the flow scheme in the operated on argon and air plasma torches. The inductive plasma torches can be applied to solve a wide range of tasks such as activation of coal-dust mixture with its further gasification, coating process for the stabilization of combustion processes as well as for the recycling processes at the mobile seaport recycling complexes. The calculations demonstrated convincingly the advantage of the operation of plasma torches with reverse vortex flow over plasma torches with “direct” vortex flow. Moreover the obtained data allow executing the assessment of thermal efficiency of inductive plasma jet and obtaining its optimal operational modes.

Simulation of Gas-Dynamic and Thermal Processes in Vortex-Stabilized, Inductively Coupled Argon–Hydrogen Plasma

The flow of vortex-stabilized argon–hydrogen plasma in a radiofrequency induction (RFI) plasma torch has been investigated using modern methods of computational fluid dynamics. Optimal values of the torch power and energy release in plasma have been found at various argon to hydrogen ratios in the plasma gas mixture. The heat and kinetic fields determined by calculation for a plasma-chemical reactor can be of use in designing an RFI plasma torch in part concerning the determination of the optimum zone for feeding the reactants to the reactor.

Mathematical Simulation of Processes in ICP/RF Plasma Torch for Plasma Chemical Reactions

This paper presents the results of mathematical simulation of processes in argon–hydrogen inductively coupled plasma/radio frequency induction plasma torch for plasma chemical reactions. This first part starts a series of papers for simulation and study of plasma properties for a variety of gases and mixtures, which could be used for a number of prospective technologies. The results of mathematical simulation allow further research on the mechanisms of chemical reactions in argon–hydrogen plasma to increase effectiveness of obtaining the target product.

Gas-dynamic and thermal processes in a high-frequency induction plasma torch with tangential stabilization of the gas flow

The gas-dynamic and heat-exchange processes in a coaxial type plasma torch with tangential stabilization of the gas flow and a central inlet for feeding the raw material into the high-temperature region of plasma at atmospheric pressure were studied. The temperature range in the high-temperature zone (3500–4000 K) and near the plasma torch walls (930–1400 K) and the residence time of the reaction mixture in the high-temperature zone were estimated. The peculiarities of the gas flow motion using a feed probe were considered. The results, in comparison with the experimental operating modes of the plasma torch, make it possible to proceed to the construction of a plasma torch of higher productivity.

Analysis of influence of mode and geometric char-acteristics on processes of high-frequency inductive plasma torch with reverse vortex flow

Analysis of influence of mode and geometric char-acteristics on processes of high-frequency inductive plasma torch with reverse vortex flow

Efficiency of inductively torch plasma operating at atmospheric pressure on destruction of chlorinated liquid wastes- A path to the treatment of radioactive organic halogen liquid wastes

The performance of a plasma reactor for the degradation of chlorinated hydrocarbon waste is reported. Chloroform was used as a target for a recently patented destruction process based using an inductive plasma torch. Liquid waste was directly injected axially into the argon plasma with a supplied power of ∼4 kW in the presence of oxygen as oxidant and carrier gas. Decomposition was performed at CHCl3 feed rates up to 400 g·h−1 with different oxygen/waste molar ratios, chloroform destruction was obtained with at least 99% efficiency and the energy efficiency reached 100 g·kWh−1. The conversion end products were identified and assayed by online FTIR spectroscopy (CO2, HCl and H2O) and redox titration (Cl2). Considering phosgene as representative of toxic compounds, only very small quantities of toxics were released (< 1 g·h−1) even with high waste feed rates. The experimental results were very close to the equilibrium composition predicted by thermodynamic calculations. At the bottom of the reactor, the chlorinated acids were successfully trapped in a scrubber and transformed into mineral salts, hence, only CO2 and H2O have been found in the final off-gases composition.

Inductively coupled plasma torch efficiency at atmospheric pressure for organo-chlorine liquid waste removal: Chloroform destruction in oxidative conditions

The performance of a plasma reactor for the degradation of chlorinated hydrocarbon waste is reported. Chloroform was used as a target for a recently patented destruction process based using an inductive plasma torch. Liquid waste was directly injected axially into the argon plasma with a supplied power of ∼4kW in the presence of oxygen as oxidant and carrier gas. Decomposition was performed at CHCl3 feed rates up to 400gh−1 with different oxygen/waste molar ratios, chloroform destruction was obtained with at least 99% efficiency and the energy efficiency reached 100gkWh−1. The conversion end products were identified and assayed by online FTIR spectroscopy (CO2, HCl and H2O) and redox titration (Cl2). Considering phosgene as representative of toxic compounds, only very small quantities of toxics were released (<1gh−1) even with high waste feed rates. The experimental results were very close to the equilibrium composition predicted by thermodynamic calculations. At the bottom of the reactor, the chlorinated acids were successfully trapped in a scrubber and transformed into mineral salts, hence, only CO2 and H2O have been found in the final off-gases composition.

Purification of silicon for photovoltaic applications

Solar grade silicon, as a starting material for crystallization to produce solar cells, is discussed here in terms of impurities whose maximum content is estimated from recent literature and conferences. A review of the production routes for each category of solar-grade silicon (undoped, compensated or heavily compensated) is proposed with emphasis on the metallurgical route.Some recent results are proposed concerning segregation, showing that directional solidification systems can be used for solidification even at high solidification rate (15cm/h). Results on inductive plasma purification, where boron is evacuated as HBO in a gas phase blown from an inductive plasma torch, are shown to apply as well to arc plasmas and purification by moist gas.Special attention is paid to the history of impurities in the purification processes, showing that impure auxiliary phases (silicon tetrachloride, slag, aluminum, etc.) often need their own purification process to enable their recycling, which has to be considered to evaluate the cost (financial, energetic and environmental) of the purification route.

A review on nano-TiO2 sol–gel type syntheses and its applications

Nanomaterials, defined as particles ranging from 1 to 100 nm diameter, have become widely utilized because of their unique physicochemical properties. Among those nanoparticles, titanium dioxide (TiO2) is frequently used in the production of paints, paper, plastics, welding rod-coating material, cosmetics, etc. TiO2 is the most commonly used semiconductor photocatalyst. Among the different nanomaterials, it is the most studied. Activated by UV-A irradiation, its photocatalytic properties have been utilized in various applications. A wealth of information on TiO2 photocatalytic in activation of bacteria has been acquired over the last 20 years. Hence, in this review article we have described synthesis methods mainly sol–gel type method like sol–gel method, ultrasonic-assisted sol–gel method, microemulsion method, colloidal synthesis, and also other method are discussed like solvo-thermal method, thermal plasma process, supersonically expanded plasma jet method, induction plasma torch, reactive plasma processing, plasma electrolytic oxidation, hydrolysis method, thermohydrolysis method, coprecipitation method, citrate–nitrate autocombustion method, etc. Also applications of TiO2 like medical applications, environmental application, sensor application, photocatalytic applications, and also its health impact for long-term exposure are discussed.

Observations of oxidation mechanisms and kinetics in faceted FeCo magnetic nanoparticles

( Fe 50 Co 50 ) 97 V 2 Nb 1 nanoparticles were synthesized in an induction plasma torch and oxidized isochronally at temperatures between room temperature (RT) and 900 °C. The particles exhibited three stages of oxidation present at different temperatures. The initial oxide layer was nearly Co-free, beginning at 3 nm at RT, and Co appeared to oxidize separately from the iron. Iron cations were determined to be the mobile species during oxidation, yielding a progressively more Co-rich core as oxidation progressed, decreasing from an average diameter of 42 to 25 nm, while the oxide tripled in size. At 350 °C, the particles exhibited a less dense core, and at 900 °C the particles were observed to have changed morphology completely with some sintering, forming completely oxidized particles with an average diameter three times the as received size.

Production of Nanopowders with an Inductive Atmospheric Plasma Torch

The production of different nanomaterials from oxides to nitrides and carbides is investigated through the control of the process parameters of an inductive atmospheric plasma torch.

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications

We report the oxidation products and qualitative rates for polydisperse FeCo magnetic nanoparticles (MNPs) synthesized using an induction plasma torch. X-ray diffraction (XRD) and TEM showed MNPs to have a thin ferrite shell. Nanopowders were isochronally annealed to promote oxidation and XRD was used to follow the evolution of the FeCo core and the Fe3O4 and FeO oxide shells. Isothermal anneals were used to follow oxidation kinetics at 350 and 500°C. High resolution transmission electron microscopy (HRTEM) revealed faceted morphologies terminated at (100) and (110) FeCo faces with (110)FeCo∥(111)oxide and (100)FeCo∥(100)oxide, and [010]FeCo∥[011]oxide orientation relationships between the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples of aqueous ferrofluids similarly loaded with as synthesized and oxidized MNPs.

Induction heating of FeCo nanoparticles for rapid rf curing of epoxy composites

FeCo magnetic nanoparticles (MNPs) have been investigated for curing polymer epoxy composites through radio-frequency (rf) heating. The rf response of functionalized FeCo MNPs is shown to uniformly cure the epoxy without parasitic heating for potential applications in electronic packaging. The FeCo/(Co,Fe)3O4 MNPs were synthesized using a rf induction plasma torch and were ultrasonicated in diglycidyl ether of bisphenol F epoxy to form stable ferrofluids. Transmission electron microscopy studies reveal as-synthesized MNPs to have a mean diameter of 17.6 nm with a 5.2 nm standard deviation. The mean MNP diameter is reduced to 9 nm after cryomilling and causes particles to form ∼200 nm agglomerates. Ferrofluids of varying MNP concentrations, sizes, and shapes were rf heated using a precision rf coil operated at 20.0 kA/m and 267 kHz frequency. Using a 1.36 vol % ferrofluid, the epoxy composite was effectively rf cured, reaching temperatures &amp;gt;100 °C in ∼70 s. The results suggest that rf heating of FeCo MNPs may provide an effective method to curing epoxy composites.

Rapid crystallization of amorphous silicon utilizing a radio-frequency thermal plasma torch

The rapid crystallization of amorphous silicon utilizing the radio-frequency (rf) inductive coupling thermal plasma torch of argon is demonstrated. Highly-crystallized Si films were fabricated on thermally grown (th-)SiO2 and textured a-Si:H:B/SnO2/glass by adjusting a distance between the tip of the silica tube and the substrate stage and the translational velocity of the substrate stage. The crystallization was promoted efficiently from the bottom to front surface during the solidification and crystallization of liquid Si.

Numerical simulation for the characterization of operating conditions of RF-RF hybrid plasma torches

A two-dimensional (r, z) numerical code has been developed to investigate the prominent features of RF-RF hybrid plasma torches with two stages of different diameter. Flow and temperature fields have been calculated within the assumptions of laminar flow and local thermodynamic equilibrium for the optically thin argon plasma operated at atmospheric pressure, taking into full account the electromagnetic interaction between the primary and the secondary stage of the hybrid device. Results from a detailed parametric study for various geometric, gas flow and electric configurations aim at putting into evidence the wide range of operating conditions that can characterize the use of RF-RF hybrid plasma torches for industrial applications, showing also their possibility to give high enthalpy plasma jets with high torch efficiencies. The magnetofluidynamic modelling described in this work can be an effective tool for providing the theoretical framework for a deep understanding of RF-RF hybrid plasma torches and for designing them as suitable sources for chemical processing of materials, when utilized within an integrated approach that would match the induction plasma torch simulation with the RF generator operating conditions to evaluate the total source efficiency for each particular hybrid configuration.