Roller Hearth Furnace for Thin Slabs

In a new mill layout for strip production, the Roller Hearth Furnaces are the most used solution in which a thin slab caster and finishing mill are connected by an inline tunnel furnace thus achieving the highest production and the best energy efficiency.

The tunnel furnace serves three key purposes.  First, the furnace provides a means to convey the thin slabs from the continuous caster to the rolling mill.  To accomplish this, the furnace enclosure incorporates in-furnace rolls that are designed to withstand the hot furnace temperatures of 1150 °C to 1220 °C.

Second, the tunnel furnace heats the hot charged slabs to the desired hot rolling temperature. Having just been cast, the thin slabs are generally charged into the furnace at temperatures between 850 °C and 1050 °C and are discharged to the rolling mill at 1150 °C to 1200 °C. Compared to Hot Strip Mill with re-heating furnace, the combination of a hotter charge temperature and a cooler discharge temperature make this layout particularly energy efficient.  The hotter charge temperature is due to the close coupling with the caster. 

Finally, the furnace is used to provide a buffer between the continuous caster and the rolling mill, so that the caster can continue to cast new steel even while the mill is unavailable due to scheduled or unscheduled delays.  For this reason, the furnace is designed with sufficient length that it can store slabs along its length in an oscillating mode, until the rolling mill can once again start processing the slabs.

Combustion systems and burners are specifically designed for a wide variety of fuels, including those ones having a poor Net Heating Value (such as BFG, PG, MG). The use of those fuels optimizes the usage of available utilities and resources at customer’s plant, minimizing the operating costs and improving the overall sustainability.