Patent ID: 6923573

Claim:
An apparatus for measuring a temperature of a molten metal, comprising: a nozzle which is configured to penetrate through a wall of a vessel accommodating a molten metal, the nozzle having a double pipe structure; inner and outer pipes; an image fiber guiding a thermal radiation light of the molten metal facing a distal end of the nozzle, the thermal radiation light of the molten metal is observed while a purge gas is passed through the inner pipe, and while a protective cooling gas for protecting a melting loss of the nozzle is passed through an annular gap space between an outer pipe and an inner pipe of nozzle, wherein a fitting portion is provided between the nozzle and the image fiber, the fitting portion including four connectable portions of the nozzle portion, a purge/cooling gas introduction portion, an image fiber fitting portion with a window glass and an image fiber protection tube; at least one joint portion disposed on the purge/cooling gas introduction portion so that an optical axis is centered for connecting the thermal radiation light of the molten metal to the image fiber; an imaging device configured to measure a two-dimensional distribution of a thermal radiation intensity, the imaging device is connected to a rear end of the image fiber, wherein the imaging device is accommodated in a sealed box having a cooling structure, and is disposed in a proximity of an outer wall of a vessel for accommodating the molten metal; and an arrangement configured to measure the temperature of the molten metal from the thermal radiation light guided by the image fiber.