| 摘要 |
PROBLEM TO BE SOLVED: To unify the product quality by minimizing the temperature gradient in a molten metal feed nozzle, and to improve the efficiency of the energy by heating the molten metal feed nozzle at an appropriate temperature. SOLUTION: A nozzle covering cylindrical body 14 with a gas inlet 20 and a plurality of gas outlets 21 cut in a circumferential wall portion, and a gas feed pipe 15 with one end fixed to the gas inlet 20 are provided. A substantially entire outer circumferential surface of the molten metal feed nozzle 12 is covered by the nozzle covering cylindrical body 14 with a predetermined space therebetween, and the combustion gas is allowed to flow inside the nozzle covering cylindrical body 14 from the gas feed pipe 15 via the gas inlet 20.
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