Abstract
Summarizing the results of previous investigations on ESR furnaces with ingot diameter from 2 to 60 cm. the empirical equations to express the relations between ingot diameter (D: cm) and various melting parameters have been derived. According to these findings ingot diameter. electrode diameter. slag depth and melting rate are selected as basic parameters. and the dependencies of all other melting parameters on ingot diameter are determined by the former four.
The thermal balance between the cooling capacity and the heat release on solidification being taken into account. it is shown that the limiting condition D·u<1.9 cm2/sec (u: solidification rate cm/ sec) must be satisfied for larger ESR ingots. This means that the solidification rate should be in inverse proportion to ingot diameter when it exceeds 100 cm. while the rate is constant (=0.01 cm/sec) for smaller ingots.
Accordingly, the melting rate will increase with ingot diameter linearly rather with its square as expected. At the same time the energy consumption (kWh/kg) will begin to increase beyond the optimum ingot diameter. which suggests that the excessive scale-up of an ESR furnace might not be favorable from the viewpoint of thermal economy.
