DE-102024003677-A1 - Control method for controlling at least one process in an industrial furnace as well as an industrial furnace

Abstract

The invention relates to a control method for controlling at least one process in an industrial furnace. The temperature within a particle-laden gas is determined by measuring the radiant power of the particles at a specific wavelength and then directly and unambiguously determining the temperature using formula (I) and taking into account two empirical parameters. The empirical parameters are wavelength-dependent and should therefore be determined separately for each wavelength range. Advantageously, the temperature measurement in the industrial furnace can be performed without contact, and it is sufficient to evaluate only a narrow wavelength range. The control method, and in particular the temperature determination, proves advantageously robust against cross-influences occurring during the process. The invention further relates to an industrial furnace.

Inventors

• Matthias Mäde

Assignees

• CTH Conrads Technologie und Holding AG

Dates

Publication Date

20260513

Application Date

20241108

Claims (13)

1. Control method for controlling at least one process in an industrial furnace as a function of a temperature of a particle-laden gas measured in the industrial furnace, characterized in that the measurement of the temperature of the particle-laden gas comprises the following steps: i. Detection of a first radiant power P of the electromagnetic radiation emitted by the particle-laden gas in a measurement wavelength range with a width of at most 2.0 µm around a measurement wavelength λ by means of a photoelectric sensor unit; ii. Determination of the temperature T of the particle-laden gas from the radiant power P using formula (I). T = ( P − a ) / b 4 where a and b are empirical parameters.
2. Control procedures according to Claim 1 , where the measurement wavelength range has a maximum width of 0.5 µm.
3. Control procedures according to Claim 1 or 2 , whereby detection according to step i. is carried out without contact.
4. Control procedure according to one of the Claims 1 until 3 , wherein, prior to step ii., the empirical parameters a and b are determined by means of a reference measurement using an alternative temperature measurement, or wherein the empirical parameters a and b are known.
5. Control procedure according to one of the Claims 1 until 4 , where the measurement wavelength range is between 0.78 µm and 20 µm.
6. Control procedure according to one of the Claims 1 until 5 , wherein the gas contains first infrared-active molecules and wherein, prior to detection according to step i., the measurement wavelength λ is determined in a radiation minimum of the first infrared-active molecules.
7. Control procedure according to one of the Claims 1 until 6 , wherein, prior to detection according to step ii., the particle-laden gas is passed through an exhaust gas discharge device and cool air is subsequently supplied to the exhaust gas stream.
8. Control procedure according to one of the Claims 1 until 7 , wherein the process which depends on the temperature of the particle-laden gas is the supply of fuel and/or the supply of an oxidizing agent.
9. Industrial furnace comprising: a furnace vessel, an adjoining exhaust gas discharge device, a measuring port, a photoelectric sensor unit for detecting the radiant power emitted through the measuring port, and an evaluation arrangement which is electrically and/or electronically connected to the photoelectric sensor unit, and which is used for the automated determination of the temperature according to one of the Claims 1 until 8 is trained.
10. industrial furnace according to Claim 9 , wherein an air supply device is arranged on the exhaust gas discharge device and the measuring opening is arranged on the exhaust gas discharge device in the direction of exhaust gas flow (R) after the air supply device.
11. industrial furnace according to Claim 9 or 10 , wherein the photoelectric sensor unit comprises a photoelectric sensor, wherein the photoelectric sensor is configured to measure in a range between 0.78 µm and 20 µm.
12. industrial oven according to one of the Claims 9 until 11 , wherein a spectral filter is arranged between the photoelectric sensor and the measuring aperture, the spectral filter having a maximum transmission width of 0.2 µm.
13. industrial oven according to one of the Claims 9 until 12 , wherein the industrial furnace is designed as a metallurgical melting furnace, comprising a heating device for melting metal in the molten bath, wherein the heating device comprises several electrically operated electrodes for generating an electric arc.

Description

The invention relates to a control method for controlling at least one process depending on the measurement of the temperature of a particle-laden gas in an industrial furnace, and to an industrial furnace that can carry out this control method automatically. For the efficient operation and precise control of industrial furnaces, knowledge of the exact temperature is essential, as the chemical reactions taking place in industrial furnaces are very temperature-sensitive. Knowing the exhaust gas temperature in industrial furnaces is crucial for several important reasons. For example, the exhaust gas temperature can provide insights into the furnace's efficiency. A significant temperature increase, for instance, can indicate that the furnace is not operating optimally and is wasting energy. Furthermore, high exhaust gas temperatures can point to overheating or a malfunction in the furnace, which can lead to safety hazards such as fires or explosions. Monitoring helps to identify and address such risks early on. Continuous monitoring of the exhaust gas temperature can even reveal signs of wear or defects in the furnace. Early detection of problems is essential to avoid costly repairs and downtime. In summary, knowledge of the exhaust gas temperature is important to optimize the operation of the furnace, minimize safety risks, comply with environmental regulations, and control operating costs. However, a disadvantage of industrial furnaces is the generation of hot, particle-laden gases due to the necessary processes involved. Measuring the temperature of these gases is technically very complex, as the high temperatures pose a significant challenge for measuring instruments. A further problem is that flowing gases are generally abrasive, while typical materials have an abrasive resistance that decreases with increasing temperature. Therefore, measuring the temperature of hot, particle-laden gases using tactile methods is either very complex or the measuring devices are subject to high wear. In industrial furnaces, for example, thermocouples are used in state-of-the-art technology to determine the temperature within the hot exhaust gases. A disadvantage of these thermocouples is that they can only withstand the high temperatures in industrial furnaces for a short time, causing them to wear out quickly. This high wear leads to high costs, and the high material consumption also has a particularly negative impact on the environment. A method for determining the temperature of a gas containing a heteromolecular gas is described. DE 10 2021 004 593 A1 A proposed method allows the determination of temperature from the emission spectra of a gas, using two photodiodes to simultaneously measure radiation intensities in two wavelength ranges. To determine the temperature, these radiation intensities are then compared with known temperature-dependent characteristic curves. A problem here is that it is usually unclear which molecules contribute to the measured radiation. Furthermore, the emissions from dust particles have a significant influence on the measured values. Another way to determine temperature using a pyrometer is in EP1647791A1 This document describes a device for non-contact temperature measurement in a melting furnace. A disadvantage is that measurements must be taken in at least two wavelength ranges. Typically, in an industrial furnace, especially an electric arc furnace (EAF), where particle-laden gases from a furnace vessel exit into an exhaust duct, the temperature is measured in areas further away from the furnace outlet. These areas further downstream in the exhaust duct have lower temperatures than those directly at and inside the furnace vessel. To determine the temperatures in the areas immediately adjacent to the furnace outlet, estimated values based on process experience were used. Precise measurements are generally not possible in these areas, resulting in detrimental inaccuracies in process control. The invention is therefore based on the objective of providing a method and a device that overcomes the disadvantages of the prior art, in particular providing a measuring method that is suitable for reliably determining the temperature in an industrial furnace. The problem is solved by a method and a device with the features of the independent claims. Further developments are specified in the dependent claims. A first aspect of the invention relates to a control method for controlling at least one process in an industrial furnace as a function of a temperature of a particle-laden gas measured in the industrial furnace. The temperature measurement comprises the following steps: i. Detection of a first radiant power P of the electromagnetic radiation emitted by the gas in a measurement wavelength range with a width of at most 2.0 µm around a measurement wavelength λ by means of a photoelectric sensor unit ii. Determining the temperature T of the particle-laden gas from the radiative power P using formu