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Stove Dome 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 stoves are divided into two sides, the combustion chamber and the brick checker work.  When the stove is “on gas,” fuel is being burned in the combustion chamber, and the heated gasses are flowing through the checker work 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 through a large refractory-lined duct called the hot blast main.

 

Benefits

  • Reliable and continuous measurement of stove dome refractory temperature provides a meaningful process control parameter.
  • Eliminates cost and inconvenience of frequent thermocouple changes.
  • More reliable and faster responding than a thermocouple.
  • Uniquely high signal dilution capability eliminates the need for routine cleaning of the sensor viewport.  Emissivity and Signal Dilution outputs may be used to monitor viewport clarity.
  • Built-in aim light allows for quick and easy fiber cable integrity check.

 

While the stove is “on gas”, extreme temperatures and turbulent air flow combine to threaten the refractory life and efficiency within the stove dome area.  The temperature within the stove dome area is a critical process parameter, indicating temperatures at the entry to the checker brick.  

 

Application Issues

  • Alignment: The dual-wavelength technology self-aligns to the hot checker brick.
  • Dirty Optics: The dual-wavelength sensor is able to tolerate a dirty viewport, as refractory dust can deposit on the window over time.
  • Environment: The NEMA4X sensor is subjected to ambient temperature extremes, attached to hot process flanges and exposed to severe winter temperatures.  The air near a blast furnace is highly acidic.

 

A dual-wavelength fiber optic sensor is recommended for this application to allow the sensor electronics to be mounted away from the hot viewport surface.  .  The dual-wavelength technology is able to compensate for optical contamination as a result of refractory dust that can accumulate on the viewport window.

 

The Williamson dual-wavelength sensors provide the highest signal dilution in the industry, eliminating the need for routine cleaning of the viewport.  Sensor ambient temperature, signal dilution, and measured emissivity values may be monitored locally or remotely to provide additional process feedback and troubleshooting tools.