As you know, in evaluating the service lifetime of a blast furnace, accurate monitoring of the erosion profile of the hearth bottom surface is a critical factor. Of the various methods available, thermocouple measurements are known to provide the best estimate of the erosion profile and the two point method, because of the high accuracy it allows, is most common employed.
In order to cool the hearth bottom refractory in a blast furnace, a stave cooler is installed in between hearth bottom refractory and iron shell, and in order to have a higher cooling efficiency, ramming material is filled in between stave cooler and heath bottom refractory, and in between stave cooler and iron shell. As a result of the cycle of expansion and contraction due to variation of temperature, some clearance gap is made in between stave cooler and ramming material. In order to bridge this clearance gap, some heavy oil paste is filled. However, if this heavy oil paste comes into the sensor, spring capability of the sensor becomes unable to function.
- This thermocouple makes a solution to the surface contact problem which keeps the thermocouple tip pressed solidly against the carbon brick even under the cycle of expansion and contraction due to variation of temperature.