METHOD FOR CONTROLLING OPENING SPEED OF LARGE BELL AT BLAST FURNACE TOP

PURPOSE:To control the opening speed of the large bell with high precision and easily by comparing the opening degree at each time of a large bell opening degree-time characteristic curve with the attained opening degree of the large bell, controlling the opening speed of the large bell and allowing the speed to approach the curve. CONSTITUTION:At the blast furnace top, the charge materials supplied through a small bell 1 is charged into the blast furnace by opening and closing a large bell 2 through a segment 4 operated by a hydraulic cylinder 6. In this process, a large bell 2 opening degree-time characteristic curve for the optimum charge of the materials in accordance with the composition distribution or the temp. distribution of the gas in the blast furnace is divided along the time axis and a constant-speed pattern approximating the curve is inputted to a large bell opening degree controller 12 from a setting device 14. Furthermore, the position and time of the large bell 2 are detected by a pulse oscillator 13 and a timer count circuit 18, the attained opening degree of the large bell 2 at the time corresponding to the sectional point is successively detected and compared with the opening degree on the curve. Consequently, a valve 11 of the hydraulic cylinder 6 in the hydraulic system is operated by the controller 12 and the opening speed of the large bell 2 is controlled.