| 摘要 |
PURPOSE:To permit easy exchanging of an immersion pipe and to extend considerably the life of a lower tank by using more than once the immersion pipe of an RH vacuum degassing device preliminarily to use for rising a molten steel thereby removing the solidified layer in the pipe. CONSTITUTION:The same immersion pipe 14 is first used as a riser up to about half its life and gaseous Ar is blown through a gas blowing pipe 16 to obtain stable reflux of molten steel. Said pipe is used as a downcomer for the remaining half of the life and during this time the gaseous Ar is not blown into the pipe and therefore the molten steel intrudes and solidifies in the pipe 16 thereby cloggint the pipe. The pipe 14 as a downcomer is used temporarily as a riser by blowing the gaseous Ar from an Ar brick 30 in the stage of RH treatment of a non-high grade steel just prior to exchanging of the pipe 14 when the pipe 14 is used to the limit and the other immersion pipe for the riser attains about half of its limit. The base metal slag, etc. sticking the inside surface of a reflux pipe 12 and the pipe 14 are therefore removed, by which the removal of the pipe 14 is made easy and the damage in the brick of the pipe 12 is thoroughly eliminated. The life of a lower tank 6 is thus considerably extended. |
