14-02-2019 дата публикации
Номер: US20190048431A1
A molten steel refining method includes throwing a powder to molten steel while heating the powder with a flame formed by combustion of a hydrocarbon gas at the leading end of a top blowing lance. The lance height of the top blowing lance (the distance between the static bath surface of the molten steel and the leading end of the lance) is controlled to 1.0 to 7.0 m, and the dynamic pressure P of a jet flow ejected from the top blowing lance calculated from equation (1) below is controlled to 20.0 kPa or more and 100.0 kPa or less. P=ρ× U/2 . . . (1) wherein P is the dynamic pressure (kPa) of the jet flow at an exit of the top blowing lance, ρthe density (kg/Nm) of the jet flow, and U the velocity (m/sec) of the jet flow at the exit of the top blowing lance. 1. A method for refining molten steel in vacuum degassing equipment , the method comprising:throwing a powder and a carrier gas toward a bath surface of molten steel in a vacuum vessel of the vacuum degassing equipment through a central hole, the central hole being disposed at a central portion of a top blowing lance that is vertically movable in the vacuum vessel; andsupplying a hydrocarbon gas from a fuel ejection hole disposed on a periphery of the central hole and supplying an oxygen-containing gas from an oxygen-containing gas ejection hole disposed on the periphery of the central hole, such that the powder falls on the molten steel while being heated with a flame formed by combustion of the hydrocarbon gas at a leading end of the top blowing lance, a lance height of the top blowing lance is 1.0 to 7.0 m, the lance height being a distance between a static surface of the bath surface and the leading end during the throwing of the powder,', [{'br': None, 'i': P=ρ', '×U, 'sub': 'g', 'sup': '2', '/2\u2003\u2003(1)'}, {'br': None, 'sub': g', 'A', 'A', 'T', 'B', 'B', 'T', 'C', 'C', 'T', 'P', 'T, 'i': ×F', '/F', '×F', '/F', '×F', '/F', '+V', 'F, 'β=ρ+ρ+ρ/(/60)\u2003\u2003(2)'}, {'br': None, 'i': U', 'F', '/S, 'sub ...
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