skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Plasma torch with liquid metal electrodes

Abstract

In order to eliminate the negative effect of erosion processes on electrodes in arc plasma generators, a new scheme of arc discharge was proposed in which the surface of a molten metal acts as electrodes. A plasma reactor was designed on the basis of this concept. The electrophysical characteristics of such a discharge in steam and air as plasma gases were studied. Experiments on destruction of toxic polychlorinated biphenyls and steam coal gasification were performed.

Authors:
;  [1]
  1. Russian Academy of Science, Novosibirsk (Russian Federation)
Publication Date:
OSTI Identifier:
20741175
Resource Type:
Journal Article
Resource Relation:
Journal Name: High Energy Chemistry (English Translation); Journal Volume: 40; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; COAL GASIFICATION; STEAM; PLASMA; ELECTRODES; LIQUID METALS; POLYCHLORINATED BIPHENYLS

Citation Formats

Predtechenskii, M.R., and Tukhto, O.M.. Plasma torch with liquid metal electrodes. United States: N. p., 2006. Web. doi:10.1134/S0018143906020093.
Predtechenskii, M.R., & Tukhto, O.M.. Plasma torch with liquid metal electrodes. United States. doi:10.1134/S0018143906020093.
Predtechenskii, M.R., and Tukhto, O.M.. Wed . "Plasma torch with liquid metal electrodes". United States. doi:10.1134/S0018143906020093.
@article{osti_20741175,
title = {Plasma torch with liquid metal electrodes},
author = {Predtechenskii, M.R. and Tukhto, O.M.},
abstractNote = {In order to eliminate the negative effect of erosion processes on electrodes in arc plasma generators, a new scheme of arc discharge was proposed in which the surface of a molten metal acts as electrodes. A plasma reactor was designed on the basis of this concept. The electrophysical characteristics of such a discharge in steam and air as plasma gases were studied. Experiments on destruction of toxic polychlorinated biphenyls and steam coal gasification were performed.},
doi = {10.1134/S0018143906020093},
journal = {High Energy Chemistry (English Translation)},
number = 2,
volume = 40,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has been developed by taking account of 3D arc current distribution and arc root rotation. The 3D simulation results apparently reveal that the 3D arc root attachment brings about the inherent 3D and turbulence nature of plasma fields inside the torch.more » It is also found that the constricted arc column near the vortex chamber plays an important role in heating and acceleration of injected arc gases by concentrating arc currents on the axis of the hollow electrodes. The inherent 3D nature of arc discharge is well preserved inside the cathode region, while these 3D features slowly diminish behind the vortex chamber where the turbulent flow begins to be developed in the anode region. Based on the present simulation results, it is noted that the mixing effects of the strong turbulent flow on the heat and mass transfer are mainly responsible for the gradual relaxation of the 3D structures of plasma fields into the 2D axisymmetric ones that eventually appear in the anode region near the torch exit. From a detailed comparison of the 3D results with the 2D ones, the arc root configuration seems to have a significant effect on the heat transfer to the electrode surfaces interacting with the turbulent plasma flow. That is, in the 2D simulation based on an axisymmetric stationary model, the turbulence phenomena are fairly underestimated and the amount of heat transferred to the cold anode wall is calculated to be smaller than that obtained in the 3D simulation. For the validation of the numerical simulations, calculated plasma temperatures and axial velocities are compared with experimentally measured ones, and the 3D simulation turns out to be more accurate than the 2D simulation as a result of a relatively precise description of the turbulent phenomena inside the torch using a more realistic model of arc root attachment. Finally, it is suggested that the 3D transient formulation is indeed required for describing the real arc discharge phenomena inside the torch, while the 2D stationary approach is sometimes useful for getting practical information about the time-averaged plasma characteristics outside the torch because of its simplicity and rapidness in computation.« less
  • Desolvated solution aerosols are injected into the axial channel of an inductively coupled plasma through a graphite tube inserted directly into the plasma. This hot injector constricts the stream of analyte and prevents it from widening excessively as it travels through the plasma. Thus, the sampling orifice for the mass spectrometer can be positioned several millimeters downstream from the tip of the initial radiation zone without substantial loss of analyte ion signal. The signal ratio for LaO{sup +}/La{sup +} can be reduced to 0.05% with conventional desolvation or 0.01% with crogenic desolvation under operating conditions that yield maximum metal ionmore » signal. These values are greatly superior to those obtained with conventional torch injectors. The graphite injector also improves sensitivity for atomic ions by factors of 1.5-15, with the best improvements seen for elements such as As and Zn that have high ionization energies. This modification to the plasma does not compromise other analytical figures of merit such as rinse-out time or the suitability of a single set of operating conditions for multielement analysis. 50 refs., 7 figs., 2 tabs.« less
  • Designing high performance liquid-metal sliding electrical contacts for homopolar machinery requires a precise knowledge of the magnitudes of the viscous and Joulean losses under various operating conditions. The liquid metal, which is confined to a channel between a rotor and stator, is subjected to a large external magnetic induction while transporting current. Significant power losses can occur in these devices. The geometry and electrical conductivity of the channel walls have a significant effect on these losses. In past theoretical work, copper electrodes were generally treated as perfect electrical conductors as compared to the liquid metals. Calculations based on this perfectlymore » conducting electrode approximation predicted unrealistically high power losses. In the present study, the effects of electrodes with finite conductivity on both the viscous dissipation and Joulean heating will be explored. Numerical results are presented for both radial and axial magnetic inductions. It is found that the magnetic induction orientation has a significant impact on the losses. The results of this type of analysis can be used to minimize the power losses in the design of liquid-metal sliding electrical contacts.« less