Power calculation of induction heating furnace

How to calculate the power required for an induksjonsvarmeovn to heat a diameter of 40 and a length of 6 meters? How to calculate the speed?

Calculation: Heat a kilogram of steel from 25 degrees to 1250 degrees in 60 seconds. Assuming the efficiency of the heater is 0.5, the required power is: 0.168×＜1250-25＞×1÷0.24÷0.5÷60=23.8kW .