| 摘要 |
PURPOSE:To prevent the ejection of an excess amt. of gas and to smooth the change over of gases to a refining furnace by changing over the control of the opening degree of a flow rate control valve of a succeeding gas supply line to a feedback control in such a manner that the flow rate of the succeeding gas attains a set flow rate in the transition period when the change over of different kinds of the gases or lines is executed. CONSTITUTION:On signals are inputted from control contact Sig 1, 8 to the mode terminals of respective PID controllers 26A, 26B prior the change over of the bottom bowing gases is controlled. The PID control is started with the reference set value SVO inputted to voltage controllers 20A, 20B as a gas flow rate set value SV. The contacts Sig 1, 2 are closed at the time of controlling the gas flow rate of the line A by controlling the respective contacts Sig 1-8 based on the chart shown in the figure in the above-mentioned control mode. The reference set value SVO of the gas flow rate is inputted at the same time and the gas A is blown to a bottom blown converter 10 only from the line A. The contacts Sig 2 are opened and the contacts Sig 3 and 8 are closed in the transition period and the value obtd. by calculating 22 the difference between the set value SVO and the gas flow rate of the B line is inputted to the controller 26A.
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