Electrical arc furnaces are composed of split able upper and lower shells. Lower Shell is refractory lined inside and is used to hold molten steel inside which is heated above 1600 0C. The upper Shell is formed of a main structural frame and pipe to pipe designed water cooled wall panels closed on top with a water cooled panel type movable (up/down and swiveling). Upper shell is used as a housing to hold the charge materials.
There are two types of arc furnaces namely AC (alternating current) and DC (Direct Current) arc furnaces. In AC arc furnaces one graphite electrode column is used for each phase (total 3), in DC furnaces only one electrode column is used.
Arc furnaces are essentially sole melting equipment and only limited metallurgical processes takes place in melting stage. Refining and alloying of steel is done in the secondary metallurgical unit called ladle furnace. VD/VOD units are steel cleaning and refining units used for producing various high quality steels.
The primary power source for EAF melting is electrical power. The EAF transformer capacities are about 0,8 -1,5 MVA/t. tapping capacity.
The second melting power source in EAF’s is wall mounted oxy/fuel combined burner-injectors. Burner power for an arc furnace can be 20- 40 % of the transformer power depending on the furnace size. Consumable lance manipulators for oxygen and carbon injection through slag door are also used in some applications.
In addition to oxy/fuel combined burner-injectors, wall mounted carbon injectors, and different type of lime injection systems are also used in arc furnaces for slag foaming purpose which enables long arc operation leading to increasing productivity and reducing consumptions. There are different tapping systems of arc furnaces and the most common and preferred one is EBT (eccentric bottom tapping).