Quick startup of a fully electrical soaking furnace for long products led to full operations in four weeks at Fagersta Stainless, Sweden.
The Danieli Centro Combustion design maintains and equalizes billet temperature between induction heater reheating furnace and rolling mill.
To achieve the process requirement, and at the same time pursue the ambitious target of decarbonization, the furnace is fully powered by electrical resistance. The resistance coils developed and tested in Danieli Research Center are installed along the entire length of the furnace roof and walls maintain the furnace chamber at temperatures up to 1250 °C, which was never reached before with this heating system.
Despite the high temperatures dry rolls are installed, and this further reduces energy consumption by the soaking furnace.
Temperature control is performed through a silicon-controlled rectifier that allows very accurate zone-temperature tuning. In addition, the insulation system mainly composed by fiber, guarantees low inertia and high reactivity of the furnace, capable to heat up and cool down quickly with 200°C/hour gradients, and maintain constantly the desired temperature with great accuracy (±2,5°C), resulting in high flexibility.
The furnace was engineered, manufactured and assembled on site in 7 months following order signature, to meet customer requirement to make it operational at Summer stoppage.
This installation represents a new benchmark for soaking furnaces for quality and carbon-free operation.
This kind of furnace find its best application in mills with differentiated rolling temperature demands due to material characteristics. In combination with Induction heating it maximizes yield by minimizing temperature setting stops in the reheating furnace –still providing a fully equalized temperature profile of billet.
It may also be applied in layouts that foresee long distances between reheating furnace and stands, or in plants operating with hot charge, for zero emissions.