| 摘要 |
PURPOSE:To prevent excessive oxidation of a steel strip under preheating by conducting the high-temp. waste combustion gas after heating the steel strip in the direct firing heating zone in a heating furnace into a separately provided combustion chamber, supplying air thereto and conducting the combustion gas having a low O2 concn. to the preheating chamber. CONSTITUTION:The waste combustion gas discharged from a direct firing heating zone 12 is conducted to a combustion chamber 10 and the unburned component contd. in said gas is burned by the air supplied to the chamber 10. The quantity of the air is so set that the concn. of O2 in the waste combustion gas after combustion of the unburned component attains, for example, about 1.0-1.5%. The quantity of the air is set on the basis of the measured value of the concn. of O2 in the preheating gas for the above- mentioned purpose. The waste combustion gas from the chamber 10 is conducted partly or wholly as a preheating gas from the outlet side of the steel strip to a preheating zone 13 to preheat the strip 14 passing in the zone 13 to a prescribed temp. The remaining preheating gas is conducted from the chamber 10 to a recuperator 16 and the preheating gas after preheating the strip 14 is discharged from the inlet side for the steel strip of the zone 13 to the recuperator 16. The air supplied to the zone 12 and the chamber 10 is released 19 into the atm. after heating. |
