Furnace method for reheating billets or slabs

Claim 1

A process for reheating billets or slabs by moving the slabs or billets through a furnace while supported on supporting means, comprising heating the slabs or billets by passing them through a preheating zone heated by a burner having a flame travelling in the same direction as the slabs or billets, then further heating the slabs or billets by passing them through a major soak zone heated by a burner having a flame travelling in the opposite direction to that of the slabs or billets, the preheating zone being greater in length than the major soak zone, supplying a greater quantity of heat to the billets or slabs in the first quarter of the combined length of the preheating zone and major soak zone than in the rest of the furnace, venting the furnace through a waste gas offtake located between the preheating and soak zones, and then discharging the slabs or billets down a discharge ramp and through a door at the bottom of the ramp, the height of the discharge ramp being arranged in relation to the momentum fluxes of the burners at their maximum firing rate so that the pressure in the furnace rises from the entry of the furnace along the length of the preheating zone, decreases along the length of the major soak zone, and further decreases along the length of the discharge ramp and is substantially equal at the bottom of the ramp to the pressure at entry.