| 摘要 |
PROBLEM TO BE SOLVED: To heat glass at high heat efficiency by an indirect heater, prevent degradation problem of the indirect heater and wholly miniaturize a melting furnace body. SOLUTION: This indirect heating device is provided with a heater insertion opening 13 penetrating a melting furnace body 2 in up and down directions at the upper position of a melting space 1, an opening and closing lid 15 placed in the upper part of the melting furnace body 2 and capable of opening and closing the heater insertion opening 13, an indirect heater 17 capable of inserting in the melting space 1 through the heater insertion opening 13, and a negative pressure maintaining casing 18 provided around the melting furnace body 2 around the opening and closing lid 15 and the indirect heater 17 from the outside.
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