E O Serba

Investigation of parameters of the three phase high-voltage alternating current plasma generator with power up to 100 kW working on steam

The paper presents the results of experimental investigation of parameters of the three-phase high voltage alternating current plasma generator with power up to 100 kW operating on steam with gas protection of the electrodes. Researches were carried out over a range of arc current from 25 to 50 A and range of steam consumption of 3–5 g/s. Current-voltage and volt consumable characteristics, operation oscillograms and dependence of power versus the flow rate of steam and protective gas are presented.

Production of synthesis gas by conversion of methane in a steam-carbon dioxide plasma

Experimental setup and results of methane conversion in a steam-carbon dioxide plasma are briefly described. Mass-flow rate of CH4 was varied from 2.5 to 3.7 g/s while mass-flow rates of H2O of ∼3 g/s and CO2 of ∼3 g/s were maintained constant. The energy consumption was 29–42 MJ per 1 kg of CH4. The H2/CO ratio in the produced synthesis gas was 2.2–2.4. The conversion rate of CH4 was 90.8–99.8%. The content of H2 and CO in the synthesis gas was ∼95%.

Study of electric arcs in an air-steam mixture in AC plasma torches

A review of existing plasma torches designed for steam plasma is presented in this paper. Together, they cover the following ranges of key technical parameters: efficiency from 51 to 95%, enthalpy of the plasma from 12 to 84 MJ/kg, and the fraction of the steam in the plasma forming gas from 17 to 100%. The advantages of alternating current to produce plasma is grounded. The problems of creating of a steam plasma torch are described. The description of the experiments carried out on the AC plasma torch, during which the total flow of the plasma forming steam-air mixture and the effective value of the current remained constant ∼ 6.7 g/s and ∼ 28.4 A, respectively, and the steam content ranged from 54 to 85%, is given. With an increasing proportion of steam, the voltage increased from 1.03 to 1.59 kV, while the estimated temperature of the arc decreased from 11600 to 10200 K, which is caused by intensification of heat transfer. In all modes, there was a high efficiency of 94.3–95.3% with a significant change in the specific energy input from 8.3 to 12.4 MJ per 1 kg of plasma-forming gas.

Spectral measurements of the gas and electron temperatures in the flame of a single-phase ac plasma generator

High-power electric-arc ac plasma generators find extensive application which is primarily associated with the problem of processing of organic waste and production of synthesis gas. The structure of a high-power single-chamber multiphase ac plasma generator with rail-type electrodes includes an injector of primary charge carriers which is a single-phase high-voltage plasma generator with a power of 10 kW or lower. This latter plasma generator may be further employed for solving other problems. Results are given of spectroscopic measurements of gas temperature fields at the nozzle exit section of a high-voltage plasma generator with rod electrodes located in a cylindrical channel. The pattern of variation of the temperature fields as a function of working gas flow rate is investigated.

AC plasma torch with a H2O/CO2/CH4 mix as the working gas for methane reforming

This paper presents results of investigations implemented during construction of the three-phase ac plasma torch working on a mixture of steam with carbon dioxide and methane (H2O/CO2/CH4) with power upto 120 kW. Such thermal plasma generators are needed in industrial technologies for methane reforming with the aim of producing the syngas comprising of the hydrogen and carbon mono-oxide (H2/CO). It was shown that during plasma torch work there are two character parts of the high-voltage arc. In these parts, the arc column has a different diameter and temperature about (8.5 − 8.3) 103 K and (10.5 − 10.0) 103 K, respectively. The plasma torch output characteristics have been obtained for working regimes with various flow rates of the methane (0.0–0.8 g s−1) in the plasma-forming mix and constant flow rates of the carbon dioxide and water steam (each of 3.0 g s−1). For the mentioned mix of gases, the unit generates plasma with the mass-average temperature ~(3.2–3.3) 103K and the thermal efficiency ~94–96%. This provides effective reforming of methane.

The investigation of an electric arc in the long cylindrical channel of the powerful high-voltage AC plasma torch

The comparison of conductivity obtained in experiments with calculated values is made in this paper. Powerful stationary plasma torches with prolonged period of continuous work are popular for modern plasmachemical applications. The maximum electrode lifetime with the minimum erosion can be reached while working on rather low currents. Meanwhile it is required to provide voltage arc drop for the high power achievement. Electric field strength in the arc column of the high-voltage plasma torch, using air as a plasma-forming gas, does not exceed 15 V/cm. It is possible to obtain the high voltage drop in the long arc stabilized in the channel by the intensive gas flow under given conditions. Models of high voltage plasma torches with rod electrodes with power up to 50 kW have been developed and investigated. The plasma torch arcs are burning in cylindrical channels. Present investigations are directed at studying the possibility of developing long arc plasma torches with higher power. The advantage of AC power supplies usage is the possibility of the loss minimization due to the reactive power compensation. The theoretical maximum of voltage arc drop for power supplies with inductive current limitations is about 50 % of the no-load voltage for a single-phase circuit and about 30 % for the three-phase circuit. Burning of intensively blown arcs in the long cylindrical channel using the AC power supply with 10 kV no-load voltage is experimentally investigated in the work. Voltage drops close to the maximum possible had been reached in the examined arcs in single-phase and three-phase modes. Operating parameters for single-phase mode were: current −30 A, voltage drop −5 kV, air flow rate 35 g/s; for three-phase mode: current (40–85) A, voltage drop (2.5–3.2) kV, air flow rate (60–100) g/s. Arc length in the installations exceeded 2 m.

The investigation of movement dynamics of an AC electric arc attachment along the working surface of a hollow cylindrical electrode under the action of gas-dynamic and electromagnetic forces

Stationary electric arc alternating current plasma torches are used today for realization of plasma chemical technologies requiring relatively high energy input. Waste treatment is one these directions. The paper reports on experiment results directed towards the increase in the lifetime characteristics of electrode units of the powerful high-voltage electric-arc AC plasma torches. The solution to the problem of obtainment the uniform wear of a copper hollow cylindrical electrode achieved by the controlled movement of the arc attachment along the working surface was offered. Organization of gas supply in the near electrode area and application of alternating magnetic field ensured movement of arc attachment along the surface with average speed from 2 to 14 m/s. Arc current was about 47 A and 84 A, gas flow rate in near electrode area was about 5 and 4.5 g/s. Due to researches on the experimental prototype of a hollow cylindrical electrode, the erosion of its material reached only 3 μg/C, that enables production of the electrode assembly with life time above 1000 hours at currents in the arc up to 100–200 A.

High voltage AC plasma torches with long electric arcs for plasma-chemical applications

Powerful AC plasma torches are in demand for a number of advanced plasma chemical applications, they can provide high enthalpy of the working gas. IEE RAS specialists have developed a number of models of stationary thermal plasma torches for continuous operation on air with the power from 5 to 500 kW, and on mixture of H2O, CO2 and CH4 up to 150 kW. AC plasma torches were tested on the pilot plasmachemical installations. Powerful AC plasma torch with hollow electrodes and the gas vortex stabilization of arc in cylindrical channels and its operation characteristics are presented. Lifetime of its continuous operation on air is 2000 hours and thermal efficiency is about 92%, the electric arc length between two electrodes of the plasma torch exceeds 2 m.

Investigation of steam-air plasma generator of alternating current

This paper presents the results of spectral and optical measurements of the experimental model of the plasma generator of alternating current working on steam-air mixture. Spectra of emission radiation of steam-air plasma describing its composition are shown. Temperature dependence in the plasma generator flame of the gas flow rate and air/steam relationship is investigated. The qualitative picture of behavior of an arc and plasma generator flame at different stages of the discharge received by high-speed shooting is studied.

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.