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Stove Zonal Temperature

Blast furnace combustion air is preheated in refractory furnaces called stoves.  The blast air is preheated in order to achieve the extreme process temperatures required for efficient production of iron.  The refractory stoves are divided into two sides, the combustion chamber and the brick checkerwork.  When the stove is “on gas” fuel is being burned in the combustion chamber, and the heated gasses are flowing through the checkerwork to heat the bricks.  When the stove is “on blast”, the checker bricks are being used as a heat exchanger to preheat the blast air.  The hot blast air is delivered to the blast furnace within a large refractory-lined duct called the hot blast main.

 

 

Benefits

  • Reliable, instantaneous, and continuous measure of stove refractory temperature allows for optimal process efficiency.
  • Eliminates cost and inconvenience of frequent thermocouple changes.
  • More reliable and faster responding than a thermocouple.

 

The measurement at the stove dome is used in concert with measurements along the height of the stove.  When “on gas” the measurement is used to optimize the transfer of heat, and to identify when the stove is fully soaked.  When “on blast” the measurement is used to identify when the heat within the checkerwork has been fully consumed.  By monitoring the temperature profile within the stove, thermal management may be optimized for greatest efficiency and for protection of the refractory.

 

Thermocouples may be used for these temperature measurements, but because they are in direct contact with the flowing hot blast air, they are prone to failure.  By using infrared thermometers, an immediate and direct measure of refractory temperature may be obtained, and troublesome maintenance issues may be eliminated.

 

 

Application Issues

  • Environment: The NEMA4X sensor is robust enough for the severe environmental demands associated with an exterior application in the hot and acidic blast furnace area.
  • Alignment/ Optics: The sensor provides precision optics and mounting accessories to view through the process viewport and to compensate for any optical contamination.

 

Dual-wavelength sensors are recommended for this application when optical contamination of the viewport is a concern, however, single-wavelength sensors may be used when the viewport window is kept clean.  The fiber optic sensor configuration is recommended to remove the sensor electronics from the hot process flange, and to eliminate the need for active cooling.