| 摘要 |
PCT No. PCT/JP89/01189 Sec. 371 Date Jul. 22, 1991 Sec. 102(e) Date Jul. 22, 1991 PCT Filed Nov. 22, 1989 PCT Pub. No. WO91/07643 PCT Pub. Date May 30, 1991.A thermocouple temperature sensor employs a protecting tube made of metal-boride-based ceramics, and a platinum -rhodium-based thermocouple. To prevent a deterioration of the thermocouple due to a reducing gas generated in the protecting when used at a high service temperature, the thermocouple is placed in an insulation tube, which is placed inside the protecting tube. In addition, a front end portion of the insulation tube is covered with a noble-metal cap mainly composed of platinum group metal, to prevent the reducing gas generated in the protecting tube from reaching a connection point of the thermocouple. The top end of the protecting tube is open, and a terminal box with a ventilation means to smoothly discharge the reducing gas in provided. This arrangement remarkably prolongs the service life of the thermocouple, and thus it is able to continuously measure the temperature of molten pig iron and molten steel for a long interval. |
