A. A. Safronov

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 application of plasma technologies to recycle organic-containing substances: Particularities of high current free burning arcs

Studies of the free burning high current arcs fanned by weak nitrogen or argon flow, with parameters typical for plasmochemical reactors and currents of about 10 kA, are performed. The electrodes were made of carbon and metals. In this case we show that, under the arc stabilization by nitrogen or argon, a significant number of charge carriers enter the arc due to ionization of carbon and metal atoms. When the high current arc is switched by a melt the main part of the arc energy is imparted into the melt and not more than 35% of the energy is transferred into the bulk of the reactor.

The Use of AC Plasma Generators for Operation as a Part of Plasma Reactor: Special Features

Various operating modes are described of an electric-arc generator of low-temperature plasma as a part of a plasmochemical facility, depending on the manner in which the power supply is connected.

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.

Electric arc plasma generator of alternating current on steam-air mixtures for plasmachemical applications

This paper is dedicated to characteristic features of operation of the high-voltage plasma generator of alternating current with rod electrodes working on a steam-air mixture. Current-voltage and volt-consumption characteristics, characteristic oscillograms of work, and results of research of influence of relationship of steam and air on electric arc parameters are represented. Researches were carried out by means of a specially developed hardware-software complex.

Investigation of power are plasma generators of alternating current for plasma chemical applications

The paper describes the results of spectral and optical measurements of power arc plasma generators of alternating current using air as a working gas. The dependence of temperature in the plasma generator flame on gas flow rate is investigated. The qualitative picture of behavior of an arc and plasma generator flame at different stages of the discharge received by means of high-speed shooting is studied. Now the significant attention is given to development of devices for generation of nonequilibrium air plasma of atmospheric pressure with electron concentration more than 1012 cm-3 and gas temperature less than 2000 K. There are a lot of applications of this type of plasma, and every year their amount increases. For example there are systems of sterilization, air-plasma hardening of materials and modification of polymer surface. Besides organic waste processing technologies are actively developed in the last decade. It is known that calorific value of many kinds of solid organic containing waste is enough for the organization of processes of their combustion with the purpose of destruction with the subsequent recuperation of part of energy. A great amount of combustion plants is created all over the world. However it rather more efficient to subject organic waste to gasification because in this case the organic component of waste will be transformed to combustible gas having a wide spectrum of opportunities on further application, the main of which is energy generation. According to the preliminary estimations and calculations the low temperature plasma application in these processes will allow essentially increasing in their efficiency, and use of plasma generators of the examined type looks very promising.