DC electric arc furnace May15

DC electric arc furnace...

DC electric arc furnace DC (direct current) arc furnace is a furnace for steel making which represents a different concept in the designs of arc furnaces. Generally DC arc furnaces have single graphite electrode (cathode) and the current flows down from this graphite electrode to an anode which is mounted in the bottom of the furnace.  Single graphite electrode exploits the highly efficient heat transfer of the arc generated between the graphite top electrode and the anode provided by the charge of the furnace. History It is generally believed that steel making by DC arc furnace is a very recent development. But this is only partially true. In 1878, Sir William Siemens used a DC arc furnace with a vertical graphite cathode, with the arc transferred to the melt in contact with a water cooled bottom anode.  Hence the concept of operating an electric arc furnace (EAF) is more than 130 years old but only in early 1970s did the costs for rectification units have drop due to the development of high power solid state rectifiers and only after it DC arc furnaces became economical. This period was the starting point for the development work for DC arc furnaces for steel making in a real sense. Significant commercialization of DC furnace technology has taken place in 1990s when around 80 numbers DC arc furnaces were built in the northern hemisphere. Basic design features In DC furnaces the electrical energy is converted into thermal energy mainly by the arc, which is established between the top electrode tip and the slag bath. The top of the electrode is connected as the cathode, and the conductive bottom system is connected as the anode. Typical DC arc furnace configuration is shown in Fig 1. Fig 1 Typical DC...