PURPOSE: To economically heat a degassing bath with good heating efficiency by moving a burner tip from a lower position to upper in the degassing bath and controlling a temp. of burner's burning flame, when a burner heats an inner part of the vacuum degassing bath.
CONSTITUTION: The inner part of the bath is preheated prior to the start of degassing refining with the immersion tube 8 only made open, in order to prevent molten steel from adhering to the inner wall of the vacuum degassing bath for molten steel due to splash and temp. down. On this occasion, many of the pure oxygen burners 2, which are arranged annularly in cross section, and the heating burner 1, which has the air hole 3 for secondary burning in the center, are inserted from the storing part of the degassing bath 4. A temp. of the lower part of bath is heated over 1500°C by controlling fuel supply quantity. Next, the burner 1 is pulled up upward, so as to heat the upper part of the bath inner part over 1100°C with the gradient for heating temp. The part, to which a molten steel easily adheres in the vacuum degassing bath by splash, etc., is heated with good heating efficiency and low cost, it prevents to deteriorate the vacuum degassing refining function due to the cause that a molten steel adheres to the inner wall of the vacuum degassing bath.
TAKAGI NOBUHIRO
YAMAUCHI HIDEKI
KUNITAKE OKITOMO
