| 摘要 |
PROBLEM TO BE SOLVED: To prevent the contamination caused by overflow of molten iron and skull stuck to a furnace wall by controlling bottom-blown gas flow rate and/or vacuum degree so that rising-up height of molten iron surface becomes lower than the height of a free board in a vessel. SOLUTION: The rising-up height(h) (mm) of the molten iron surface is calculated by equation I. In equation I, C: proportional constant (=1.5×105), Qg: bottom-blown gas flow rate (Nl/min), T1: molten iron temp. (K), P: vacuum degree (torr),ρ1: molten iron density (kg/m3) and H: bath depth (mm). Further, He: exclusive bath depth (mm) obtd. by equation II. In equation II, d: gas bubble diameter (mm) at the initial stage (=13 mm). Further, A: plume area (mm2), calculated by equation III. In this method, since the precise rising-up height of the molten metal surface can be estimated, the bottom-blown gas flow rate and/or the vacuum degree can be controlled and the operation can be stabilized.
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