| 摘要 |
PROBLEM TO BE SOLVED: To attain the continuous operation of a heating furnace with a low air ratio, even in the case that a heating furnace with a high air ratio is not operated. SOLUTION: In an operating method of direct-firing heating furnaces provided with combustion burners, with which the combustion treatment is performed by supplying unburnt exhaust gas from the heating furnace with the low air ratio into the heating furnace with the high air ratio and thus, the unburnt exhaust gas is utilized as the heat source in the heating furnace with the high air ratio, two sets of the heating furnaces 6A, 6B with the high air ratio, are set. Then, in the case of carrying out steel material 13B from the one side of the heating furnace 6A with the high air ratio, the supply of the unburnt exhaust gas from the heating furnace 5 with the low air ratio, is changed over into the other side of the heating furnace 6B with the high air ratio. |
