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How to detect the lining thickness of a high-temperature electric furnace?

How to detect the lining thickness of a high-temperature electric furnace?

1. Capacitance method

The capacitance method is similar to the resistance method. A coaxial circular capacitor sensor is embedded inside the furnace lining, and the capacitance value corresponds to its length. The thickness of the blast furnace masonry can be determined by measuring the capacitance value.

2. Stress wave method

The stress wave signal is very sensitive to structural defects. When the stress wave propagates in the medium, such as holes, cracks and other interface discontinuities, reflection, refraction, scattering and mode conversion will occur. The thickness of the stave material can be determined.

3. Resistance method

The resistance element is embedded inside the furnace lining, the front of the sensor is aligned with the inner surface of the furnace lining, and it is connected to the measurement system through a lead wire. The resistance value of the resistance element is related to its length. As the resistance element and the furnace lining lose synchronously, the resistance will change. Use the corresponding measurement The meter measures the electrical signal output by the component, and then the remaining thickness of the furnace lining can be measured online.

4. Heat flow detection method

According to thermodynamics, temperature difference, thermal conductivity and furnace wall thickness determine the heat flow intensity. For blast furnace lining, the thermal conductivity is fixed, and the furnace wall thickness can be obtained from the temperature difference and heat flow intensity.

The heat flow detection sensor is installed in the lower temperature part of the furnace lining. The heat flow intensity is calculated by the water temperature difference of the cooling wall of the hearth, and the temperature value measured by the thermocouple in the brick lining is combined to calculate the thickness of the furnace wall.

5. Ultrasonic method

The thickness measurement is carried out at the point where the ultrasound propagates in the solid medium. At a constant temperature, the ultrasound is incident on the furnace lining and enters the furnace. The propagation time of the incident and reflection of the ultrasound in the furnace lining is used to obtain the residual thickness of the furnace lining.

6. Multi-head thermocouple method

Several thermocouples of different lengths are installed in a protective sleeve, and then they are installed in the brick lining that needs to be inspected, and the erosion of the masonry can be inferred by measuring the temperature change of each thermocouple. When the temperature of each point and the temperature gradient between each point are basically stable, when the brick lining is gradually eroded to a certain part, the galvanic couple in that part will be destroyed, and the temperature signal will be abnormal.

7. Model inference method

It uses thermocouples as detection elements, applies thermodynamics and other theories to establish a mathematical model of the hearth and furnace bottom temperature site, and calculates the approximate positions of the molten iron solidification line and carbon brick erosion line through software programming and numerical analysis.