| 摘要 |
PURPOSE:To maintain a minimum of total gas flow at switching time, by a method wherein gas is switched from the preceding gas to the following, using a valve opening that provides a minimum flow to prevent molten steel from entering the tuyere, and under a virtual condition that there is no mushroom at each end of the tuyere. CONSTITUTION:The preceding gas A is maintained at a constant flow rate up to time e; and in order to switch it to the following gas B, the valve of the preceding gas A is reduced, at time f, to the specified opening at which molten metal does not enter the tuyere, if mushroom drops. At time g, the valve of the following gas B is made to the specified opening, then, at time h, each gas flow becomes nearly the same, and total flow reaches a peak. Then, a time g, the valve of the preceding gas A is closed and, at time j, the flow rate of the preceding gas A is made to 0. At this time, the valve of the following gas B is maintained at the specified opening, so that following gas B also corresponds. At time k, the bollowing gas B is controlled to the flow that meets the requirement of flowing operation after switching gas, and gas switching is completed. |
