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2021 №02 (02) DOI of Article
10.37434/sem2021.02.03
2021 №02 (04)

Electrometallurgy Today 2021 #02
SEM, 2021, #2, 19-25 pages

Problems and their solution at application of higher power steam-water plasmatrons

Authors
S.V. Petrov
Institute of Gas of the NAS of Ukraine 39 Dehtiarivska Str., 03113, Kyiv, Ukraine. E-mail: vizana.sp@gmail.com

Abstract
Implementation of new technologies of multiton plasma chemistry requires development of reliable higher-power longlife plasmatrons. During plasmatron operation, the cathode undergoes the most intensive wear, the anode life being approximately two times longer. Ingenious designs of steam-water transferred-arc plasmatrons were developed with application of two types of cathode assemblies: tungsten (PLR-3P) and copper tubular one (PLR-4P). In the latter the low level of tubular cathode erosion is ensured by distribution of the heat flow from the arc support point to a large area as a result of its fast movement (~ 100 m/s) due to gas-dynamic and magnetic forces that act on the arc radial region. Here, the arc spot scans the electrode working surface, while being between the aerodynamic and magnetic planes. At operation of PLR-4P plasmatron at 300 A current the cathode erosion was 9∙10–7 g/C for air, and for water steam it was 3∙10–7 g/C. More over, when water steam is used, the cathode surface remains clean and erosion level does not depend on operation time, whereas at operation in air the surface is covered by a black film of copper oxide (CuO). It is found that self-extinction of the electric arc can occur in the blind electrode, because of fluctuations of current and voltage and gas-dynamic instability of the vortex flow. In order to avoid self-extinction of the electric arc, 12-phase rectification circuits should be used for supplying power to steam-water plasmatrons of higher power (100…500 kW). Ref. 27, Fig. 6.
Keywords: steam-water plasmatron; tubular cathode; erosion; magnetic vortex stabilization of arc; self-extinguishing of arc

Received 25.03.2021

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