| 摘要 |
PURPOSE:To obtain a steel strip having good surface characteristic by estimating reducing force from component concns. in composition gas and controlling a mixed ratio of the fuel gas and the air so as to become a prescribed reducing force. CONSTITUTION:Burners 2 faced to both surfaces of the steel strip S are arranged in a directly firing reduction heating zone 1. An optical gas component analyzer 3 for analyzing the gas components in the combustion flame F (or combustion gas) is arranged at the position faced to the width direction of the steel strip S. The gas component concns. of CO, CO2 and H2O near the steel S are measured with this analyzer 3. The reducing force of the combustion flame F or the combustion gas is estimated by the gas component concns. and the mixed ratio of the fuel gas and the air is controlled so as to become the prescribed reducing force by using a gas component concn. arithmetic unit 8, reducing force arithmetic unit 9 and valve control device 10. By this method, the reduction heating operation can stably be executed. |
