High-Power Plasma Torches and Transferred Arcs

Abstract

High-power plasma torches and transferred-arc furnaces have been developed over many decades. The first of these megawatt devices goes back to the late 1940s where Chemische Werke Hüls AG, in Germany, developed an 8 MW torch for the synthesis of acetylene from coal in a hydrogen plasma (Gladish 1969). Significant developments followed, driven by the Apollo Aerospace program, in the USA (Aerotherm Division of Accurex), and its equivalent program in the former Soviet Union. Multiple high-power plasma systems were developed and constructed for the testing of materials under reentry conditions, operating at power levels up to 60 or 70 MW. Although most of the high-power plasma torches developed at that time are no longer in use, the know-how acquired during this period was later used for the design and manufacture of a wide range of high-power plasma torches for applications in the metallurgical and chemical process industries as well as for the destruction of toxic waste. In this chapter, the main design features and typical operating conditions of some of the most important plasma torch designs and transferred-arc furnaces are presented. In each of these categories, subgroups are identified according to the type of electrodes used, whether cold or hot electrodes, and the arc stabilization mode. Further information about the integration of these plasma torches in different industrial-scale process technologies are described in Part IV of this book.