Vasily N. Shiryaev

Possibilities of application of plasma technologies to recycle organic-containing substances: Particularities of the processes in the arc chambers of plasma torches

The processes in the arc chambers of AC plasma torches, of 1–2 MW power, with rod electrodes, designed to run on nitrogen, hydrogen, and argon, as well as with rail electrodes to work on oxidizing media, are considered. The possibility (the efficiency) of application of such plasma torches for gasification and pyrolysis of organic-containing substances in plasmochemical reactors is analyzed. A comparison of this application with the free burning arcs directly in the plasmochemical reactors is made. The advantage of the plasma torch application for these purposes is shown.

Possibilities of applying plasma technologies for processing organics-containing substances: The effect of the shape of the voltage curve on the working mode of the plasma torch

The features of alternating current plasma torches with rod electrodes and the phenomena and regularities observed during their work in a wide power range of 0.1–7 MW are considered. The mechanism of the reignition of the arc in the single-phase and three-phase working modes of a plasma torch is studied. The characteristic differences of these processes, the existence of which is explained by the conservation of the concentration of current carriers in the interelectrode gap in the three-phase mode, are given. It is shown that the reignition voltage varies in accordance with the variation of the temperature of the electrode surface, and the electrode temperature saturated with the increase in the current and the reignition voltage is constant. Particular attention is paid to analysis of the external characteristics of plasma torches in different working modes when using nitrogen, hydrogen, or argon as the working gas. The effect of the physical parameters of plasma on the shape of the voltage curves and current–voltage characteristic of arcs is considered, and the dependence of the energy parameters of plasma torches on them is described.

Plasma technologies of solid and liquid toxic waste disinfection

There is waste (hazardous and toxic waste), which should not be mixed with industrial waste and garbage. Its formed in small proportion and should be processed or disposed according to special technologies. It includes radioactive waste, war waste (WTA, missile fuel, etc.) toxic and supertoxic industrial waste, hazardous and toxic medical waste. A number of experimental treatment technologies of some kinds of waste with application of low temperature air plasma generators on AC three-phase current of commercial frequency have been developed. They have some advantages. Ionized plasma particles are chemically active that makes the process more intensive. Use of air (heated in the plasma generator up to high temperature) as an oxidizing agent decreases flue gases quantity. High temperature provides high quenching rate, which allows creating methastable and non-equilibrium states Application of plasma generators of commercial frequency essentially decreases their cost due to a great number of standard equipment. Use of electric energy instead of fuel in a number of cases is more profitable on cost indexes. The process of temperature mode control in the furnace is more simple at the expense of possibility to change thermal capacity of the plasma jet.

Multi-phase AC plasma generators

Design, principle of operation, technical data, physical parameters and volt-ampere characteristics of multi-phase systems applied in the installations on destruction of hazardous waste, including medical ones, are shown by the example of three-phase AC plasma generator. It is described: operation peculiarities of the electrode system of multiphase AC plasma generators; properties of various materials, including composite materials on the basis of silicon carbide, used for production of plasma generator electrodes.

Use of Alternating-Current Plasma Torch for Processing Potentially Hazardous Substances

The decomposition of tetrachloromethane and tetrafluoromethane by air plasma in the presence of methane has been studied using an ac plasma torch of up to 500 kW power with rail electrodes. Methane reacts with air in the partial oxidation mode to form hydrogen, which reacts with a halogen to produce the hydrogen halide.

Analysis of high-frequency processes in an electric-discharge chamber of a three-phase plasma torch at high working gas pressure

The paper deals with electrophysical processes in an electric-discharge chamber of a three-phase AC plasma torch with nitrogen as working gas. The frequency characteristics of voltage pulsations depending on current, gas mass flow rate, power, and pressure are obtained. Photos of arc burning processes in the plasma torch discharge chamber at different parameters are presented. It is shown that two arcs burn simultaneously in the plasma torch chamber and the third one either extinguishes or arises. These investigations might be useful when creating various technological processes by applying three-phase AC plasma torches operating on inert gases.

Research of operation features of electrode units of high-voltage plasma generators of alternating current, definition of the criteria influencing the electrode lifetime at plasma generator operation on steam

At a modern level of industrial development the problem of waste processing has assumed a new significance. New laws and more strict standards are imposed every year in the majority of countries. Large industrial companies and municipal structures in this situation are forced to invest significant founds in waste destruction. Each year the creation of environmentally friendly technologies of waste treatment gets the increasing investment appeal. Plasmachemical technology is the most perspective technology of waste recycling. It is based on high-temperature plasmachemical action and complete decomposition of utilized products by means of arc plasma with useful product (synthesis-gas) production, which is a mixture of hydrogen and carbon oxide and is a valuable power raw material. One of the requirements to electric arc plasma generators working in plasmachemical installations is a long lifetime of continuous operation. First of all time of continuous operation of the plasma generator is determined by lifetime of its electrode unit. Now it is perspective to use steam as a plasmaforming environment. The idea of steam use as a working body is often put forward as one of alternatives to air plasma. Water has high heat of steam formation successfully combining properties of plasmaforming substance and cooling heat-carrier. Steam is an ideal plasmaforming environment. It is ecological, explosion-proof and available working substance favorably influencing on the ecological conditions in examined gasification processes.The paper depicts the investigation results carried out at development of plasma generators using steam as a plasmaforming environment. Modern methods of manufacturing of electrode materials allow creation of composite materials of complex composition by introduction of more refractory material in a copper matrix. The noticeable increase in life time and decrease in the specific flow rate (wear) of electrode material gives prospect in the further researches and development of new kinds of materials, that at steam application as a working body creates a wide spectrum of use of these high-voltage plasma generators at gasification and pyrolysis plants.