METHOD FOR FIRING FURNACE WITH CHAMBERS FOR PRELIMINARY AND FINAL HEATING OF METAL AND FURNACE FOR PERFORMING THE SAME Russian patent published in 1999 - IPC

FIELD: metallurgy, namely processes and furnaces for low-oxidation and non-oxidation heating of steel products such a wire, possibly in metallurgical and machine engineering plants. SUBSTANCE: method comprises steps of non-complete burning of 10-100% of total consumption quantity of used fuel in final heating chamber over intermediate hearth; completely burning under intermediate hearth remained fuel and afterburning by means of excess air non-complete combustion products supplied from over-hearth space at summed relation of fuel and air consumptions close to stoichiometric values (αΣ= 1.05-1.10); while heating elongated products with diameter up to 1.2 mm in final heating chamber over intermediate hearth, providing non-complete burning of 10-30% of totally consumed fuel, heating primary air in under-hearth space up to 550-650 C, filling the whole over-hearth space of final heating chamber and soaking in homogeneous low-oxidation atmosphere. When elongated products with diameter more than 1.2 mm are heated in final heating chamber over intermediate hearth, at recrystallization annealing 60-100% of fuel is non-completely burned, at patenting - 40-60%, at heating before quenching -30-50%. Necessary temperature ranges such as 700-750 C, 900-950 C, 1050-1150 C are provided for heating and soaking metal respectively. At non-complete combustion over intermediate hearth of 60-100% of fuel, in under-hearth space of chamber for final heating and soaking in heating zone only secondary air is supplied to several burners. In remaining burners fuel is burned with factor α=1.05-1.1. In soaking zone all burners are cut off. At non-complete combustion over intermediate hearth of 10-60% of fuel in under-hearth space of soaking zone fuel is completely burned with air consumption factors close to stoichiometric values and in heating zone - at substantial excess of air (α=1.1-2.00) while using excess air as secondary one for afterburning products of non-complete combustion. In working space of final heating chamber over intermediate hearth there are burners for non-complete combustion of fuel and under that space - burners for complete combustion of fuel and afterburning non-complete combustion products supplied from over-hearth space. Intermediate hearth is assembled of heat conductive sections arranged with gap along furnace except its charging end, zone of mounting recuperator for heating primary air and soaking zone of final heating chamber. EFFECT: high speed low-oxidation heating and soaking of large assortment of metal at small delay and high efficiency of furnace. 5 cl, 4 dwg, 1 exp, 1 tbl