Multi-point temperature measuring thermocouple sensor and electromagnetic induction smelting furnace

Abstract

The application discloses a multi-point temperature measuring thermocouple sensor and an electromagnetic induction smelting furnace. The sensor comprises ceramic filling material, a metal shielding sleeve and two or more thermocouples. The thermocouples extend along the axial direction of the metal shielding sleeve and are arranged side by side in the interior of the metal shielding sleeve. Each thermocouple comprises a thermocouple wire, a metal shielding layer and an insulating layer. The insulating layer wraps the thermocouple wire, and the metal shielding layer wraps the insulating layer. The ceramic filling material fills the interior of the metal shielding sleeve and wraps the thermocouples. The measuring points on different thermocouples are located at different axial positions of the metal shielding sleeve. The measuring points can sequentially contact the ceramic filling material through the insulating layer and the metal shielding layer. The application can be applied to extreme industrial temperature measuring scenes with high temperature and strong electromagnetic coupling.

Description

Technical Field

[0001] This invention relates to the technical fields of electromagnetic induction melting, temperature control in metallurgical preparation, and testing of the corrosion resistance of high-melting-point materials. Specifically, it relates to a multi-point temperature-measuring thermocouple sensor and an electromagnetic induction melting furnace. Background Technology

[0002] Thermocouples, as temperature sensors based on the Seebeck effect, are widely used in industries such as petrochemicals, power energy, and metallurgical manufacturing due to their simple structure, wide temperature range, and fast response. However, the output signal of a thermocouple is typically in the microvolt range, making it highly susceptible to external electromagnetic interference, which can lead to a decrease in measurement accuracy. Currently, electromagnetic shielding is mainly used in engineering to improve anti-interference capabilities. Based on the shielding mechanism, it can be divided into electrostatic shielding, electromagnetic shielding, and magnetic shielding. In thermocouple systems, a metal shielding layer is typically used to cover the compensating wires to reduce the coupling effect of external electromagnetic fields. In addition, different shielding and insulating materials are used to adapt to different temperature environments, such as stainless steel, high-temperature alloys, and ceramic fibers, to meet the requirements of high-temperature operating conditions. In industrial scenarios such as induction heating, radio frequency power supplies, and high-frequency welding, the 100kHz–150kHz high-frequency electromagnetic environment is becoming increasingly common. This frequency band also covers the noise of power electronic switches and the operating frequency range of industrial radio frequency equipment, resulting in high electromagnetic interference intensity and a complex spectrum. Compared with traditional power frequency interference, high-frequency electromagnetic interference has a more significant impact on thermocouple measurement systems, easily leading to increased measurement errors. Studies have shown that in such environments, the measurement error of thermocouples without effective protective measures can reach more than ±10℃.

[0003] Existing anti-interference technologies are mainly designed for low-frequency or narrowband interference, and their adaptability in the kHz to MHz frequency band is insufficient. Specifically, in existing technologies, the shielding effectiveness of metal shielding layers is significantly reduced under high-frequency conditions due to the skin effect; conventional RC filter circuits experience performance degradation at high frequencies; and ferrite devices also have limited suppression effects in specific frequency ranges. Furthermore, different types of thermocouples (such as K-type and C-type) have significantly different applicable temperature ranges and installation environments, making it difficult for existing general-purpose anti-interference solutions to meet the precise measurement requirements in high-temperature, multi-point, and complex electromagnetic environments. To address this, existing technology CN205593666U proposes a thermocouple sensor with electromagnetic interference protection, comprising: a metal protective tube, a shielding layer, a thermocouple wire, an insulating sleeve, a heat shrink tubing, a metal shielding mesh, and an Ω connector. One end of the thermocouple wire is plastic-sealed by the insulating sleeve, and the plastic-sealed thermocouple wire is fitted inside the metal protective tube. The shielding layer is disposed between the insulating sleeve and the metal protective tube. The metal shielding mesh is fitted onto the lead portion of the thermocouple wire, and the heat shrink tubing is disposed between the lead portion and the metal protective tube. The end of the lead portion is connected to the Ω connector.

[0004] However, none of the existing technologies mentioned above can completely solve the aforementioned technical problems. Therefore, developing anti-interference technologies suitable for high-temperature multi-point thermocouple measurements in kHz to MHz high-frequency electromagnetic environments has significant engineering application value and is a practical necessity. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the first aspect of this invention provides a multi-point temperature-measuring thermocouple sensor, comprising a ceramic filling material, a metal shielding sleeve, and two or more thermocouples, all of which extend along the axial direction of the metal shielding sleeve and are arranged side-by-side inside the metal shielding sleeve; each thermocouple includes a thermocouple wire, a metal shielding layer, an insulating layer, and a measuring point, wherein the insulating layer wraps the thermocouple wire, and the metal shielding layer wraps the insulating layer; the ceramic filling material fills the interior of the metal shielding sleeve, and the measuring points located on different thermocouples are located at different axial positions on the metal shielding sleeve, and the measuring points can directly contact the ceramic filling material through the insulating layer and the metal shielding layer in sequence.

[0007] Furthermore, the thickness of the metal shielding sleeve is at least three times the skin depth of the electromagnetic signal in the operating frequency band.

[0008] Furthermore, the metal shielding sleeve is made of a high-melting-point metal material with a thermal conductivity of not less than 50 W / (m·K).

[0009] Furthermore, the metal shielding layer comprises two or more layers of metal mesh, and the thickness of the metal shielding layer is greater than 0.2 mm.

[0010] Furthermore, the metal mesh adopts a dense weave structure, and the mesh density of the metal mesh is not less than 200 meshes.

[0011] Furthermore, the insulating layer is made of rubber.

[0012] Furthermore, the ceramic filler material is a metal oxide with a melting point above 2800°C.

[0013] Furthermore, the metal oxide is a particulate material, and the particle size distribution range of the metal oxide particles is 5-100 μm.

[0014] Furthermore, it also includes an inert gas, which is filled inside the metal shielding sleeve.

[0015] Furthermore, it also includes two or more insulating sleeves, which are located inside the metal shielding sleeve and enclose the thermocouple.

[0016] Furthermore, the heat insulation sleeve is made of chromium oxide, and the wall thickness of the heat insulation sleeve 2 is 0.3mm-0.7mm.

[0017] Furthermore, the thermocouple is a type C tungsten-rhenium thermocouple.

[0018] To achieve the above objectives, a second aspect of the present invention provides an electromagnetic induction melting furnace, including the aforementioned multi-point temperature measuring thermocouple sensor, wherein the metal shielding sleeve portion of the thermocouple sensor is located inside the melting furnace, and the thermocouple of the thermocouple sensor is connected to an external information acquisition device.

[0019] By applying the above-described technical solution of the present invention, at least the following technical effects are achieved: 1. The thermocouple sensor proposed in this invention can operate stably in electromagnetic interference environments in the kHz to MHz frequency band, and its temperature measurement range covers room temperature to 2300℃. It is suitable for extreme industrial temperature measurement scenarios with high temperature and strong electromagnetic coupling, thereby significantly improving the environmental adaptability and signal reliability of the thermocouple measurement system.

[0020] 2. The thermocouple sensor proposed in this invention sets up a ceramic filling material between the thermocouple and the metal shielding sleeve to form an insulating and thermally conductive layer. While achieving electrical insulation and electromagnetic isolation, it effectively optimizes the heat conduction path, reduces the temperature response time, and suppresses the temperature stratification convergence phenomenon caused by internal inert gas convective heat transfer, thereby improving the authenticity and stability of the measurement data.

[0021] 3. The thermocouple sensor proposed in this invention is equipped with multiple thermocouples, enabling multi-point synchronous temperature measurement. When multiple thermocouples are set inside the metal shielding sleeve and arranged in a reasonable manner, a high-density spatial temperature measurement network can be formed, thereby realizing the fine spatial distribution measurement of the temperature field and improving the temperature field reconstruction capability and engineering application adaptability.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of a multi-point temperature-measuring thermocouple sensor in one embodiment is shown; Figure 2 A schematic diagram of the structure of an electromagnetic induction melting furnace in one embodiment is shown.

[0024] Reference numerals: 1. Thermocouple; 2. Insulating sleeve; 3. Ceramic filler material; 4. Metal shielding sleeve; 5. Insulating heat insulation ring; 6. Mounting connection thread; 7. Tightening head; 8. Compensating wire; 9. Sealing plug; 10. Multi-point temperature measuring thermocouple sensor; 11. Power supply; 12. Transformer; 13. Melting furnace shell; 14. Lifting servo rod; 15. Induction coil; 16. Copper cold crucible; 17. High-temperature molten material; 18. Material to be melted. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] The present invention will be further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0027] Example

[0028] According to one aspect of the present invention, a multi-point temperature-measuring thermocouple sensor is provided, such as... Figure 1 As shown, the device includes a ceramic filler material 3, a metal shielding sleeve 4, and two or more thermocouples 1. Each thermocouple 1 extends axially along the metal shielding sleeve 4 and is arranged side-by-side inside the metal shielding sleeve 4. Each thermocouple 1 includes a thermocouple wire, a metal shielding layer, an insulating layer, and measuring points. The insulating layer wraps around the thermocouple wire, and the metal shielding layer wraps around the insulating layer. The ceramic filler material 3 fills the interior of the metal shielding sleeve 4. The measuring points located on different thermocouples 1 are located at different axial positions within the metal shielding sleeve 4, and the measuring points can directly contact the ceramic filler material 3 through the insulating layer and the metal shielding layer in sequence.

[0029] Specifically, in this embodiment, the thermocouple 1 is a type C tungsten-rhenium thermocouple. An insulating and thermally conductive layer is formed between the measuring point of the thermocouple 1 and the metal shielding sleeve 4 by a ceramic filler material 3. This reduces the temperature response time and prevents the temperature convergence problem caused by internal gas convection heat transfer, improving the spatial temperature resolution of the thermocouple 1 and the accuracy of the measurement data. The measuring point of the thermocouple 1 is only exposed within the ceramic filler material 3, which significantly reduces electromagnetic interference and ensures accurate response to temperature changes. The measuring point of the thermocouple 1 does not contact the inner wall of the metal shielding sleeve 4; otherwise, the shielding function would fail, and accurate temperature data could not be obtained.

[0030] Preferred, such as Figure 1As shown, in this embodiment, the multi-point temperature measuring thermocouple sensor is provided with 3 thermocouples 1, the distance between the measuring points on each thermocouple 1 is 5 cm, and the diameter of the thermocouple wire is 0.3 mm.

[0031] The thickness of the metal shielding sleeve 4 is at least three times the skin depth of the electromagnetic signal in the operating frequency band. The metal shielding sleeve 4 is made of a high-melting-point metal material with a thermal conductivity of not less than 50 W / (m·K).

[0032] Specifically, in this embodiment, the metal shielding sleeve 4 is made of tungsten, which can provide high-temperature protection above 2300℃ and outer electromagnetic shielding function. In other embodiments, the metal shielding sleeve 4 is also made of high-melting-point metal materials such as molybdenum, tantalum, tungsten alloy, molybdenum alloy, or tungsten-copper composite material to further improve its high-temperature resistance, thermal conductivity, and electromagnetic shielding performance.

[0033] It should be noted here that the metal shielding sleeve withstands the electromagnetic signal frequency range during actual operation. Specifically, in this embodiment, the operating frequency band is kHz-MHz, and the skin depth of tungsten metal in this operating frequency band is 0.2mm~3mm. Preferably, the thickness of the metal shielding sleeve 4d is 3mm.

[0034] Furthermore, the metal shielding layer comprises two or more layers of metal mesh, and the thickness of the metal shielding layer is greater than 0.2 mm. The metal mesh adopts a dense woven structure, and the mesh density of the metal mesh is not less than 200 meshes. The insulating layer is made of rubber.

[0035] Preferably, in this embodiment, the metal shielding layer is made of copper, with an overall outer diameter of 1-2 mm. The metal shielding layer and the metal shielding sleeve 4 form a composite shielding structure, achieving a double shielding effect and improving the signal-to-noise ratio.

[0036] In other embodiments, the metal shielding layer may also be made of metal materials with good conductivity, such as silver, aluminum, copper alloy, or silver-plated copper, to improve its electromagnetic shielding performance.

[0037] It should be noted that the dense weave structure refers to a mesh structure formed by interlacing warp and weft threads of metal wires, wherein the warp and weft threads form a mesh structure in an interlacing manner, and the mesh density is not less than 200 meshes.

[0038] The multi-point temperature-measuring thermocouple sensor also contains an inert gas, which fills the interior of the metal shielding sleeve 4. The ceramic filler material 3 is a metal oxide with a melting point above 2800℃. The metal oxide is a particulate material with a particle size distribution range of 5-100μm. Specifically, in this embodiment, the ceramic filler material 3 is magnesium oxide powder. Before filling the ceramic filler material 3, the metal shielding sleeve 4 is evacuated and then injected with inert gas to prevent oxygen from oxidizing and damaging the tungsten-rhenium thermocouple wire at high temperatures; during the filling process, the powder porosity is reduced to below 40% by means of vibration and pressing. In other embodiments, the ceramic filler material 3 can also be a single metal oxide such as zirconium oxide and hafnium oxide, or a composite material formed by mixing two or more metal oxides in any proportion.

[0039] Preferably, the inert gas is argon.

[0040] The multi-point temperature-measuring thermocouple sensor further includes two or more insulating sleeves 2, which are located inside the metal shielding sleeve 4 and enclose the thermocouple 1. The insulating sleeves 2 are made of chromium oxide, and their wall thickness is 0.3mm-0.7mm. Preferably, in this embodiment, the thickness of the insulating sleeve 2 is 5mm. The hafnium oxide insulating sleeve has a thermal conductivity of 1-2 W / m·K and possesses a certain structural strength, effectively blocking the influence of external high temperatures on the thermocouple insulation layer and the copper mesh shielding layer.

[0041] Furthermore, such as Figure 1 As shown, the multi-point temperature measuring thermocouple sensor also includes an insulating heat insulation ring 5, a mounting connection thread 6, a screw head 7, a compensating wire 8, and a sealing plug 9. One end of the insulating heat insulation ring 5 is connected to the metal shielding sleeve 4, and the other end of the insulating heat insulation ring 5 is connected to the screw head 7. The mounting connection thread 6 wraps around the insulating heat insulation ring 5. The mounting connection thread 6 is used to realize the installation connection of the thermocouple sensor with the external structure. The insulating heat insulation ring 5 can block the transmission of electromagnetic signals with the contact surface of the external copper crucible, metal wall, etc.

[0042] The compensating wire 8 is wrapped with a metal shielding layer. One end of the compensating wire 8 is connected to the thermocouple 1, passes through the screw head 7, and connects to the sealing plug 9 to achieve flexible extension and transmission of the thermocouple signal. The positive and negative terminals and the grounding terminal of the compensating wire 8 are connected to the sealing plug 9, thereby providing external signal shielding. The sealing plug 9 is used to achieve sealed output of the thermocouple signal. The number of positive and negative terminals inside matches the number of thermocouples 1, and they are connected to the metal shielding layer in all the compensating wires 8. It shares a common ground with the external metal wall such as the furnace body through the metal shell, thereby achieving stable signal transmission while meeting the sealing requirements of the negative pressure or vacuum structure.

[0043] Specifically, the screw head is made of epoxy resin, the screw head 7 has a diameter of 20-30mm, and the side of the screw head 7 is provided with an anti-slip surface to enhance assembly reliability and achieve tail end structure sealing.

[0044] According to a second aspect of the present invention, an electromagnetic induction melting furnace is provided, including the aforementioned multi-point temperature measuring thermocouple sensor 10, wherein the metal shielding sleeve 4 portion of the thermocouple sensor 10 is located inside the melting furnace, and the thermocouple 1 of the thermocouple sensor 10 is connected to an external information acquisition device.

[0045] Specifically, such as Figure 2 As shown, the electromagnetic induction melting furnace also includes a power supply 11, a transformer 12, a melting furnace shell 13, a lifting servo rod 14, an induction coil 15, a copper cold crucible 16, a high-temperature molten material 17, and a material to be melted 18. Three multi-point temperature-measuring thermocouple sensors are arranged in the electromagnetic induction melting furnace, extending from the flange at the bottom of the furnace body through a sealed plug 9, and grounding the furnace body. This allows the thermocouple signals to be transmitted to an external acquisition system while meeting the sealing requirements of a 0.1Pa negative pressure or vacuum structure.

[0046] By applying the above-described technical solution of the present invention, at least the following technical effects are achieved: 1. The thermocouple sensor proposed in this invention can operate stably in electromagnetic interference environments in the kHz to MHz frequency band, and its temperature measurement range covers room temperature to 2300℃. It is suitable for extreme industrial temperature measurement scenarios with high temperature and strong electromagnetic coupling, thereby significantly improving the environmental adaptability and signal reliability of the thermocouple measurement system.

[0047] 2. The thermocouple sensor proposed in this invention sets up a ceramic filling material between the thermocouple and the metal shielding sleeve to form an insulating and thermally conductive layer. While achieving electrical insulation and electromagnetic isolation, it effectively optimizes the heat conduction path, reduces the temperature response time, and suppresses the temperature stratification convergence phenomenon caused by internal inert gas convective heat transfer, thereby improving the authenticity and stability of the measurement data.

[0048] 3. The thermocouple sensor proposed in this invention is equipped with multiple thermocouples, enabling multi-point synchronous temperature measurement. When multiple thermocouples are set inside the metal shielding sleeve and arranged in a reasonable manner, a high-density spatial temperature measurement network can be formed, thereby realizing the fine spatial distribution measurement of the temperature field and improving the temperature field reconstruction capability and engineering application adaptability.

[0049] The above are merely several specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0051] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A multi-point temperature measurement thermocouple sensor, characterized in that, It includes ceramic filling material (3), metal shielding sleeve (4) and two or more thermocouples (1), all of which extend along the axial direction of the metal shielding sleeve (4) and are arranged side by side inside the metal shielding sleeve (4); The thermocouple (1) includes a thermocouple wire, a metal shielding layer, an insulating layer, and a measuring point. The insulating layer wraps the thermocouple wire, the metal shielding layer wraps the insulating layer, and the ceramic filling material (3) fills the interior of the metal shielding sleeve (4). The measuring points located on different thermocouples (1) are located at different axial positions on the metal shielding sleeve (4). The measuring points can directly contact the ceramic filling material (3) through the insulating layer and the metal shielding layer in sequence.

2. The multi-point temperature measurement thermocouple sensor according to claim 1, characterized in that, The thickness of the metal shielding sleeve (4) is at least three times the skin depth of the electromagnetic signal in the working frequency band.

3. The multi-point temperature measurement thermocouple sensor according to claim 2, characterized in that, The metal shielding sleeve (4) is made of a high melting point metal material with a thermal conductivity of not less than 50 W / (m·K).

4. The multi-point temperature measurement thermocouple sensor according to claim 1, characterized in that, The metal shielding layer comprises two or more layers of metal mesh, and the thickness of the metal shielding layer is greater than 0.2 mm.

5. The multi-point temperature measurement thermocouple sensor according to claim 4, characterized in that, The metal mesh adopts a dense weave structure, and the mesh density of the metal mesh is not less than 200 meshes.

6. The multi-point temperature measurement thermocouple sensor according to claim 4, characterized in that, The insulating layer is made of rubber.

7. The multi-point temperature measurement thermocouple sensor according to claim 1, characterized in that, The ceramic filler material (3) is a metal oxide with a melting point above 2800℃.

8. The multi-point temperature measurement thermocouple sensor according to claim 7, characterized in that, The metal oxide is a particulate material, and the particle size distribution range of the metal oxide particles is 5-100 μm.

9. The multi-point temperature measurement thermocouple sensor according to claim 8, characterized in that, It also includes an inert gas, which is filled inside the metal shielding sleeve (4).

10. The multi-point temperature measurement thermocouple sensor according to claim 1, characterized in that, It also includes two or more heat insulation sleeves (2), which are located inside the metal shielding sleeve (4) and enclose the thermocouple (1).

11. The multi-point temperature measurement thermocouple sensor according to claim 10, characterized in that, The heat insulation sleeve (2) is made of chromium oxide material, and the wall thickness of the heat insulation sleeve (2) is 0.3mm-0.7mm.

12. The multi-point temperature-measuring thermocouple sensor according to any one of claims 1-11, characterized in that, The thermocouple (1) is a type C tungsten-rhenium thermocouple.

13. An electromagnetic induction melting furnace, characterized in that, The thermocouple sensor (10) includes any one of claims 1-12, wherein the metal shielding sleeve (4) of the thermocouple sensor (10) is located inside the smelting furnace, and the thermocouple (1) of the thermocouple sensor (10) is connected to an external information acquisition device.

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