Molten steel level is difficult to measure as a result of high-temperature medium and the covering flux. The characteristic of the steelmaking process is that a strong stratification of the temperature gradients is formed between different layers. Thus, temperature gradient is proposed as the principle for measuring the molten steel level. According to the new principle, a refractory material sensor is inserted into the tundish to sense the temperature distribution of the different layers. After adequate heat transfer, the sensor is lifted, and an area charge-coupled device camera is used to capture the temperature distribution of the sensor through radiation thermometry. Then temperature gradients for the different layers are extracted from the sensor and utilized to identify the molten steel level. However, there is a problem that lifting of the sensor destroys the original temperature distribution and gradients before lifting. For this issue, finite element method software ANSYS is adopted to theoretically analyze the temperature decline of the sensor during the lifting process. Due to radiation, the decay rate of the temperature on the sensor surface is the fastest, disabling the acquirement of the original temperature gradients for the different layers from the sensor. A temperature field restoration method is proposed by extracting the highest temperatures of all the thermal images during the lifting process. Based on the restored temperature gradients, sequential clustering is utilized to identify the molten steel level. Verifications with numerical data and thermal images from the actual on-site applications demonstrate the effectiveness of the new principle and measuring method.

A Novel Principle for Molten Steel Level Measurement in Tundish by Using Temperature Gradient

A specially designed air-cooled compact antenna is proposed for non-contact real-time radio detection and ranging (RADAR)-level measurement in furnace. 3-D modeling is used to optimize the surface profile of the RADAR antenna for beam symmetry and low sidelobe level over 20–24 GHz. The fabricated RADAR sensor deployed in mono-static mode has 0.19-mm measurement error for a static target. Measurements in a closed furnace at 1100 °C demonstrate the feasibility of non-contact in-situ monitoring of the level of molten metal for long duration (11 hours) without degradation in the sensor performance.

Design and Demonstration of a RADAR Gauge for In-Situ Level Measurement in Furnace

New approach for dielectric constant detection using a microstrip sensor

Step-frequency continuous-wave (SFCW) modulation can have a role in the detection of small unmanned aerial vehicles (UAV) at short range (less than 1–2 km). In this paper, the theory of SFCW range detection is reviewed, and a specific method for correcting the possible range shift due to the Doppler effect is devised. The proposed method was tested in a controlled experimental set-up, where a free-falling target (i.e., a corner reflector) was correctly detected by an SFCW radar. This method was finally applied in field for short-range detection of a small UAV.

A Doppler Range Compensation for Step-Frequency Continuous-Wave Radar for Detecting Small UAV.

Since the number of flying small unmanned aerial vehicles (UAV) is expected to increase dramatically in the next years, their radar detection has become a priority. In this paper Continuous Wave Step Frequency (CWSF) is evaluated as possible modulation for radar sensors aimed to detect small quadcopters at short range.

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CWSF radar for detecting small UAVs

Measurement of molten glass level in glass furnaces is a key issue for the control of the production process. Nowadays several different technologies shall be used for this purpose, with their advantages and drawbacks. In this paper a novel level sensor is proposed, it is based on radar interferometry technique, and it is designed to provide high accuracy measurements, high reliability and a very low maintenance.

F. Puccioni

Papers

Microwave sensor for molten glass level measurement