Steelmaking in Induction Furnace May24

Steelmaking in Induction Furnace...

Steelmaking in Induction Furnace Coreless induction furnaces have been used in the ferrous industry for over 50 years and are now one of the most popular means of melting and holding ferrous materials. Induction melting had dramatic growth during the 1960s based on line frequency technology, and later with the large-scale introduction of medium frequency power supply during the 1980s. Making of mild steel in the induction furnace was first experimented during early 1980s and it gained popularity when the production of sponge iron utilizing coal based process of rotary kilns became popular. Induction furnace is a type of electric melting furnace which uses electric current to melt metal. The principle of induction melting is that a high voltage electrical source from a primary coil induces a low voltage, high current in the metal (secondary coil). Induction heating is simply a method of transfer of the heat energy. Two laws which govern induction heating are (i) electromagnetic induction, and (ii) the joule effect. Coreless induction furnace comprises a relatively thin refractory crucible encircled by a water cooled copper coil excited from a single AC supply. When the coil is energized, the fluctuating axial magnetic field causes a current to flow in electrically conducting pieces of charge material within the crucible. The power induced in the charge depends on the physical properties of the material, the flux linking it and its geometric shape. Dependent on the resistivity of the material being melted, the coreless induction furnace converts electrical energy to heat the charge at an efficiency of between 50 % and 85 %, although furnace efficiency is further reduced by thermal losses from radiation from the melt surface and conduction through the furnace lining. Medium frequency induction furnaces which are commonly used for steelmaking use...