A composite temperature measuring system and method suitable for an internal string type graphitization furnace

Abstract

The present application relates to the technical field of furnace temperature measurement, and particularly relates to a composite temperature measurement system and a temperature measurement method suitable for an inner string type graphitization furnace, which mainly solves the technical problems of low reliability, inability to realize long-term stable temperature measurement and inability to comprehensively cover the full temperature range when the existing temperature measurement structure is applied to the inner string type graphitization furnace. The system comprises a graphite base rod, a non-contact colorimetric temperature measurement subsystem, a contact type optical fiber temperature measurement subsystem, a contact type thermocouple temperature measurement subsystem and an upper computer. The non-contact colorimetric temperature measurement subsystem comprises a colorimetric temperature measurement module. The contact type optical fiber temperature measurement subsystem comprises a single crystal optical fiber, an optical fiber coupler, an armored light transmission optical fiber and an optical-electric conversion circuit. The contact type thermocouple temperature measurement subsystem comprises a thermocouple body, a constant temperature tank and a compensation lead. The system can improve the reliability of temperature measurement data, realize long-term stable and continuous temperature measurement of the furnace core area, and cover the full temperature range of the graphitization furnace.

Description

Technical Field

[0001] This invention relates to the field of furnace body temperature measurement technology, and in particular to a composite temperature measurement system and method suitable for internally connected graphitization furnaces. Background Technology

[0002] The internal series graphitization furnace is a core piece of equipment in the production process of lithium-ion battery anode materials. The operating temperature in its core area typically exceeds 2000℃, reaching up to 3000℃. The furnace is filled with highly reducing carbon vapor, accompanied by corrosive media such as sulfur. Under these extreme conditions, accurate and reliable temperature measurement of the core area is a crucial prerequisite for optimizing the process, reducing energy consumption, ensuring the safe and stable operation of the furnace, and guaranteeing consistent product quality.

[0003] Existing temperature measurement structures face several insurmountable technical bottlenecks when applied to this type of internally connected graphitization furnace. Specifically: First, the furnace walls of internally connected graphitization furnaces, designed to ensure heat preservation and operational safety, lack lateral openings, and the furnace roof is covered with a several-meter-thick insulation layer. This structural limitation prevents non-contact temperature measurement structures from directly capturing thermal radiation signals from the furnace core area, resulting in low temperature measurement reliability. Second, the protective sheaths and other auxiliary components of contact temperature measurement structures (such as thermocouples) are highly susceptible to oxidation and carburization reactions in the high-temperature reducing atmosphere inside the furnace, leading to embrittlement and failure, making long-term stable temperature measurement impossible. Third, neither single contact nor non-contact temperature measurement structures can fully cover the entire temperature range (room temperature to 3000℃) of the internally connected graphitization furnace, making it difficult to continuously output reliable temperature data and meet the production process's requirements for full-cycle temperature measurement.

[0004] Therefore, there is an urgent need for a temperature measurement structure that can adapt to the extreme working environment of an internally connected graphitization furnace, and has high reliability, long-term stability and a wide temperature measurement range, in order to solve the long-standing temperature measurement problem in this scenario in the industry. Summary of the Invention

[0005] To overcome the technical shortcomings of existing temperature measurement structures when applied to internally connected graphitization furnaces, such as low reliability, inability to achieve long-term stable temperature measurement, and inability to fully cover the entire temperature range, this invention provides a composite temperature measurement system and method suitable for internally connected graphitization furnaces.

[0006] The present invention provides a composite temperature measurement system and method suitable for internally serial graphitization furnaces, comprising:

[0007] A graphite base rod having a first channel, a second channel and a third channel, all three channels being axial blind holes with openings extending to the same end face of the graphite base rod, the graphite base rod being used to penetrate the top of the graphitization furnace and contact the furnace core area.

[0008] A non-contact colorimetric temperature measurement subsystem is arranged based on the first channel. The inner wall of the first channel is coated with an emission coating to form an isothermal blackbody cavity. An optical window is sealed at the opening of the first channel. The non-contact colorimetric temperature measurement subsystem includes a colorimetric temperature measurement module, which is configured to receive radiation from the isothermal blackbody cavity corresponding to the optical window.

[0009] A contact-type fiber optic temperature measurement subsystem is configured based on a second channel. An optical fiber sealing plug is provided at the opening of the second channel. The contact-type fiber optic temperature measurement subsystem includes a single-crystal optical fiber, an optical fiber coupler, an armored optical fiber, and a photoelectric conversion circuit. The single-crystal optical fiber is placed inside the second channel. One end of the single-crystal optical fiber forms a single-crystal blackbody cavity and contacts the bottom of the second channel. The other end of the single-crystal optical fiber is connected to the armored optical fiber through the optical fiber coupler. The armored optical fiber seals through the optical fiber sealing plug and is connected to the photoelectric conversion circuit.

[0010] A contact thermocouple temperature measurement subsystem is provided based on the third channel. A thermocouple sealing plug is provided at the opening of the third channel. The contact thermocouple temperature measurement subsystem includes a thermocouple body, a constant temperature bath, and a compensating wire. The thermocouple body passes through the thermocouple sealing plug. The high-temperature end of the thermocouple body contacts the bottom of the third channel. The low-temperature end of the thermocouple body is placed in the constant temperature bath and led out through the compensating wire.

[0011] The host computer is communicatively connected to the colorimetric temperature measurement module, photoelectric conversion circuit, and compensation wires to calculate the real-time acquired temperature of each temperature measurement subsystem.

[0012] Furthermore, the outer wall of the graphite-based rod is provided with an anti-oxidation and anti-carburization protective layer.

[0013] Furthermore, the antioxidant and carburizing protective layer is a silicon carbide layer or a composite coating composed of a pyrolytic carbon transition layer and a silicon carbide layer.

[0014] Furthermore, the emission coating is a yttrium-stabilized zirconium oxide coating or a silicon carbide coating.

[0015] Furthermore, the optical window is a sapphire window.

[0016] Furthermore, the single-crystal optical fiber is a sapphire single-crystal optical fiber, and the single-crystal blackbody cavity is a single-crystal magnesium oxide blackbody cavity.

[0017] Furthermore, the depth of the first channel and the depth of the second channel are equal and both are greater than the depth of the third channel.

[0018] Furthermore, the thermocouple body is a tungsten-rhenium thermocouple, and the surface of the tungsten-rhenium thermocouple wire is coated with an anti-oxidation coating.

[0019] Furthermore, the composite temperature measurement system also includes an inert gas filling component. The first channel is connected to the third channel. The side wall of the first channel has a first air inlet that connects to the outside. The side wall of the second channel has a second air inlet that connects to the outside. The inert gas filling component is connected to both the first air inlet and the second air inlet and is used to fill the three channels with inert gas.

[0020] The temperature measurement method for internally connected graphitization furnaces provided by this invention uses the aforementioned composite temperature measurement system for internally connected graphitization furnaces for temperature measurement:

[0021] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 0℃<T≤1500℃, the temperature value measured by the contact thermocouple temperature measurement subsystem shall be taken as the furnace core temperature.

[0022] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 1500℃<T≤2300℃, the temperature value measured by the contact fiber optic temperature measurement subsystem shall be taken as the furnace core temperature.

[0023] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 2300℃<T≤3000℃, the temperature value measured by the non-contact colorimetric temperature measurement subsystem shall be taken as the furnace core temperature.

[0024] When the temperatures measured by the three temperature measurement subsystems are in different temperature ranges, the temperature value measured by the contact fiber optic temperature measurement subsystem is taken as the furnace core temperature.

[0025] The technical solution provided by this invention has the following advantages compared with the prior art:

[0026] The composite temperature measurement system provided by this invention utilizes a specialized carrier—a graphite-based rod with three channels. This rod penetrates the top of the graphitization furnace and directly contacts the furnace core area. The channels serve as high-temperature resistant, sealed, and safe measurement channels for each temperature measurement subsystem, enabling direct, interference-free, in-situ detection of the core high-temperature zone of the furnace core. This effectively avoids measurement deviations caused by heat loss and environmental interference in traditional external temperature measurement methods, significantly improving the reliability of the temperature data. Simultaneously, the graphite-based rod itself has high material compatibility with the furnace core area and can withstand the graphitization high-temperature environment above 2300℃ inside the furnace, achieving long-term stable and continuous temperature measurement of the furnace core area, thus solving the problems of conventional temperature measurement methods. This system addresses the technical pain points of components being prone to burnout and having short lifespans. Furthermore, it integrates three different temperature measurement subsystems based on various principles: non-contact colorimetric temperature measurement, contact fiber optic temperature measurement, and contact thermocouple temperature measurement. These subsystems form a complementary, three-in-one detection structure. The non-contact colorimetric temperature measurement subsystem is suitable for rapid detection in the ultra-high temperature range of the furnace core area; the contact fiber optic temperature measurement subsystem ensures accurate detection in the medium- and high-temperature ranges; and the contact thermocouple temperature measurement subsystem enables stable monitoring in the low-temperature range. The fusion of these three measurement modes not only covers the entire temperature range of the graphitization furnace but also further improves temperature measurement accuracy across the entire temperature range through mutual calibration and verification using multi-source data.

[0027] The temperature measurement method provided by this invention, through the structural design of the aforementioned composite temperature measurement system and the synergistic effect of multi-principle temperature measurement, can accurately match the high-temperature operating conditions of the internal series graphitization furnace, providing reliable data support for the control of graphitization process parameters of carbon products such as graphite electrodes and lithium battery anode materials, and helping to improve the graphitization uniformity and finished product qualification rate of the products. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the composite temperature measurement system in an embodiment of the present invention;

[0031] Figure 2 express Figure 1 A magnified view of a section at point A in the middle;

[0032] Figure 3 This diagram illustrates the distribution of the three channels in an embodiment of the present invention.

[0033] Figure 4 This diagram illustrates the usage status of the composite temperature measurement system in this embodiment of the invention.

[0034] Figure 5 This is a logical diagram illustrating the temperature measurement method in an embodiment of the present invention.

[0035] In the picture:

[0036] 1. Graphite-based rod; 11. First channel; 12. Second channel; 13. Third channel; 14. Anti-oxidation and anti-carburization protective layer; 15. First air inlet; 16. Second air inlet; 2. Non-contact colorimetric temperature measurement subsystem; 21. Isothermal blackbody cavity; 22. Optical window; 23. Colorimetric temperature measurement module; 3. Contact fiber optic temperature measurement subsystem; 31. Fiber optic sealing plug; 32. Single-crystal fiber; 33. Fiber optic coupler; 34. Armored optical fiber; 35. Photoelectric conversion circuit; 36. Single-crystal blackbody cavity; 4. Contact thermocouple temperature measurement subsystem; 41. Thermocouple sealing plug; 42. Thermocouple body; 43. Constant temperature bath; 44. Compensating wire; 5. Host computer;

[0037] 100, Furnace wall; 200, River sand layer; 300, Carbon black layer; 400, Insulation layer; 500, Furnace core area. Detailed Implementation

[0038] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0039] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of the invention.

[0040] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] Example 1

[0042] Reference Figures 1 to 4 This embodiment provides a composite temperature measurement system suitable for an internally connected graphitization furnace, including a graphite rod 1, a non-contact colorimetric temperature measurement subsystem 2, a contact fiber optic temperature measurement subsystem 3, a contact thermocouple temperature measurement subsystem 4, and a host computer 5.

[0043] The graphite rod 1 has a first channel 11, a second channel 12 and a third channel 13. All three channels are axial blind holes and their openings extend to the same end face of the graphite rod 1. The graphite rod 1 is used to penetrate the top of the graphitization furnace and contact the furnace core area 500.

[0044] Specifically, the graphite rod 1 in this embodiment is made of high-purity isostatic graphite with a purity of ≥99.99% and a density of ≥1.85g / cm3, and is obtained by precision machining.

[0045] It is easy to understand that when the graphite rod 1 is inserted into the top of the graphitization furnace, the openings of the three channels extend to the top surface of the graphite rod 1 to connect to the external temperature measurement subsystem.

[0046] In this embodiment, an anti-oxidation and anti-carburization protective layer 14 is also provided on the outer wall of the graphite rod 1.

[0047] Specifically, the type of the antioxidant and carburizing-resistant protective layer 14 is not limited. For example, in this embodiment, the antioxidant and carburizing-resistant protective layer 14 is a silicon carbide layer, which is prepared by chemical vapor deposition and has a thickness of 100 μm to 200 μm. In other embodiments, a pyrolytic carbon transition layer may be deposited on the graphite rod 1 first, followed by a silicon carbide layer, and the composite coating consisting of the pyrolytic carbon transition layer and the silicon carbide layer may be used as the antioxidant and carburizing-resistant protective layer 14 to enhance adhesion and thermal shock resistance.

[0048] The non-contact colorimetric temperature measurement subsystem 2 is arranged based on the first channel 11. The inner wall of the first channel 11 is coated with an emission coating to form an isothermal blackbody cavity 21. An optical window 22 is sealed at the opening of the first channel 11. The non-contact colorimetric temperature measurement subsystem 2 includes a colorimetric temperature measurement module 23. The colorimetric temperature measurement module 23 is set to correspond to the optical window 22 so as to receive the radiation from the isothermal blackbody cavity 21.

[0049] Specifically, the type of emission coating is not limited. For example, in this embodiment, the emission coating is a yttrium-stabilized zirconia coating. The yttrium-stabilized zirconia coating is applied to the inner wall of the first channel 11 by plasma spraying, with a thickness of 50 μm to 100 μm. After high-temperature sintering, its effective emissivity is stabilized at above 0.95. In other embodiments, the emission coating may also be a silicon carbide coating.

[0050] Specifically, in this embodiment, the optical window 22 is a sapphire window. The sapphire window is fixed to the opening of the first channel 11 by a high-temperature sealant and a metal pressure ring. The diameter of the sapphire window is 20mm and the thickness is 3mm.

[0051] Specifically, the colorimetric temperature measurement module 23 in this embodiment uses a near-infrared band with a wavelength range of 1.0μm to 1.1μm when it is working.

[0052] The temperature measurement principle of the non-contact colorimetric thermometry subsystem 2 is as follows:

[0053] Heat from the furnace core region 500 is conducted through the graphite-based rod 1 to the isothermal blackbody cavity 21 of the first channel 11, causing the isothermal blackbody cavity 21 to heat up and generate thermal radiation light. The thermal radiation light passes through the optical window 22 and is received by the colorimetric temperature measurement module 23. The colorimetric temperature measurement module 23 has a built-in dual-channel detector. By measuring the ratio of the radiation intensity of the two channels, the temperature of the isothermal blackbody cavity 21 is directly calculated, which is the furnace core temperature. This temperature signal is transmitted to the host computer 5 through a signal line. The non-contact colorimetric temperature measurement subsystem 2 is mainly used to achieve accurate measurement of the furnace core temperature in the range of 2300℃ to 3000℃.

[0054] The contact fiber optic temperature measurement subsystem 3 is based on the second channel 12. The opening of the second channel 12 is provided with a fiber optic sealing plug 31. The contact fiber optic temperature measurement subsystem 3 includes a single crystal fiber 32, a fiber optic coupler 33, an armored optical fiber 34, and a photoelectric conversion circuit 35. The single crystal fiber 32 is placed in the second channel 12. One end of the single crystal fiber 32 forms a single crystal blackbody cavity 36 and contacts the bottom of the second channel 12. The other end of the single crystal fiber 32 is connected to the armored optical fiber 34 through the fiber optic coupler 33. The armored optical fiber 34 is sealed through the fiber optic sealing plug 31 and connected to the photoelectric conversion circuit 35.

[0055] Specifically, in this embodiment, the single-crystal fiber 32 is a sapphire single-crystal fiber 32, and the single-crystal blackbody cavity 36 is a single-crystal magnesium oxide blackbody cavity; the diameter of the sapphire single-crystal fiber 32 ranges from 0.5mm to 1.0mm, and the length ranges from 1m to 2m.

[0056] Specifically, in this embodiment, the armored optical fiber 34 is a quartz armored optical fiber.

[0057] Specifically, the method of forming the single-crystal blackbody cavity 36 is not limited. For example, in this embodiment, the single-crystal magnesium oxide blackbody cavity is formed at the end of the sapphire single-crystal optical fiber 32 by sintering. In other embodiments, the single-crystal blackbody cavity 36 can also be formed at the end of the single-crystal optical fiber 32 by welding.

[0058] It should be noted that, in order to ensure the thermal conductivity between the single-crystal blackbody cavity 36 and the bottom of the second channel 12, a high-temperature thermally conductive adhesive can be applied between the single-crystal blackbody cavity 36 and the bottom of the second channel 12 to ensure that the single-crystal blackbody cavity 36 and the bottom of the second channel 12 are in close contact.

[0059] The temperature measurement principle of the contact fiber optic temperature measurement subsystem 3 is as follows:

[0060] Heat from the furnace core region 500 is conducted through the graphite-based rod 1 to the single-crystal blackbody cavity 36 at the bottom of the second channel 12, causing the single-crystal blackbody cavity 36 to heat up and generate thermal radiation light. This thermal radiation light is collected by the single-crystal optical fiber 32, and conducted through the optical fiber coupler 33 and the armored optical fiber 34 to the photoelectric conversion circuit 35. The photoelectric conversion circuit 35 converts the thermal radiation light into an electrical signal and calculates the temperature of the single-crystal blackbody cavity 36, i.e., the furnace core temperature. This temperature signal is transmitted to the host computer 5 through a signal line. The contact fiber optic temperature measurement subsystem 3 is mainly used to achieve accurate measurement of the furnace core temperature within the range of 1500℃ to 2300℃.

[0061] The contact thermocouple temperature measurement subsystem 4 is based on the third channel 13. The opening of the third channel 13 is provided with a thermocouple sealing plug 41. The contact thermocouple temperature measurement subsystem 4 includes a thermocouple body 42, a constant temperature bath 43 and a compensating wire 44. The thermocouple body 42 passes through the thermocouple sealing plug 41. The high temperature end of the thermocouple body 42 contacts the bottom of the third channel 13. The low temperature end of the thermocouple body 42 is placed in the constant temperature bath 43 and led out through the compensating wire 44.

[0062] Specifically, in this embodiment, the depth of the first channel 11 and the depth of the second channel 12 are equal and both greater than the depth of the third channel 13. Since the third channel 13 is used to install the thermocouple body 42, and the thermocouple body 42 has the weakness of short lifespan under extreme high temperatures, this embodiment reduces the depth of the third channel 13, so that the bottom temperature of the third channel 13 is in a relatively low temperature gradient region, thereby reducing the operating temperature of the high-temperature end of the thermocouple body 42 and delaying aging failure.

[0063] It is important to note that this design results in the temperature measured by the thermocouple body 42 not being the actual temperature of the furnace core region 500. Therefore, it must be used in conjunction with a heat transfer inverse model. The heat transfer inverse model is used to inversely deduce the actual temperature of the furnace core region 500 based on the temperature measured by the thermocouple body 42. Since there is a fixed correspondence between the actual temperature of the furnace core region 500 and the temperature at the bottom of the third channel 13, this correspondence is related to factors such as the specific depth of the third channel 13, which can be derived by those skilled in the art through a limited number of experiments. The shallower depth design of the third channel 13, combined with the heat transfer inverse model, can meet the dual requirements of long sensor life and high measurement fidelity.

[0064] Specifically, in this embodiment, the thermocouple body 42 is a tungsten-rhenium thermocouple, and the surface of the tungsten-rhenium thermocouple wire is coated with an anti-oxidation coating.

[0065] More specifically, the type of tungsten-rhenium thermocouple is not limited. For example, in this embodiment, the tungsten-rhenium thermocouple is a type C tungsten-rhenium thermocouple with a wire diameter of 0.5 mm and a protective tube outer diameter of 3 mm. In other embodiments, the tungsten-rhenium thermocouple may also be a type D tungsten-rhenium thermocouple.

[0066] More specifically, the antioxidant coating in this embodiment is a molybdenum silicide antioxidant coating.

[0067] It should be noted that, in order to ensure the thermal conductivity between the high-temperature end of the thermocouple body 42 and the bottom of the third channel 13, a high-temperature thermally conductive adhesive can be applied between the high-temperature end of the thermocouple body 42 and the bottom of the third channel 13 to ensure close contact between the high-temperature end of the thermocouple body 42 and the bottom of the third channel 13.

[0068] It is easy to understand that, although the connecting cable of the thermocouple body 42 is... Figure 1 Although only a single cable is used to represent it, as is known to those skilled in the art, the thermocouple body 42 should have two connecting cables, one for the positive pole and one for the negative pole, and the compensating wire 44 should also have two cables, one for the positive pole and one for the negative pole.

[0069] Specifically, the thermostatic bath 43 is used to ensure the measurement accuracy of the thermocouple body 42, and the type of thermostatic bath 43 is not limited. For example, in this embodiment, the thermostatic bath 43 is an ice-point device capable of maintaining 0°C. In other embodiments, the thermostatic bath 43 may also be a semiconductor zero-degree thermostat.

[0070] The working principle of the contact thermocouple temperature measurement subsystem 4 is as follows:

[0071] Heat from the furnace core region 500 is conducted to the bottom of the third channel 13 via the graphite-based rod 1. Because the third channel 13 is relatively shallow, the temperature at the bottom of the third channel 13 is lower than the furnace core temperature. The high-temperature end of the thermocouple body 42 senses the temperature at the bottom of the third channel 13 and generates a corresponding thermoelectric potential. This thermoelectric potential is transmitted to the host computer 5 via the compensating wire 44, and the furnace core temperature is calculated using the heat transfer inverse model integrated within the host computer 5. The contact thermocouple temperature measurement subsystem 4 is mainly used to achieve accurate measurement of the furnace core temperature within the range of 0℃ to 1500℃.

[0072] The host computer 5 is connected to the colorimetric temperature measurement module 23, the photoelectric conversion circuit 35, and the compensation wire 44 to calculate the real-time temperature of each temperature measurement subsystem.

[0073] It is easy to understand that the host computer 5 integrates a data acquisition module and a processing module. The data acquisition module is used to synchronously receive temperature signals from the three temperature measurement subsystems, and the processing module is used to compare the three temperature signals and obtain the actual temperature value of the furnace core area 500 according to the preset judgment logic.

[0074] Furthermore, the composite temperature measurement system of this embodiment also includes an inert gas filling assembly. The first channel 11 is connected to the third channel 13. The side wall of the first channel 11 has a first air inlet 15 that connects to the outside, and the side wall of the second channel 12 has a second air inlet 16 that connects to the outside. The inert gas filling assembly is connected to both the first air inlet 15 and the second air inlet 16 and is used to fill the three channels with inert gas. Before use, the fiber optic sealing plug 31 and the thermocouple sealing plug 41 are opened first, and then a slightly positive pressure inert gas is filled into the three channels through the first air inlet 15 and the second air inlet 16. Finally, the fiber optic sealing plug 31 and the thermocouple sealing plug 41 are closed. This can effectively isolate the intrusion of carbon vapor and dust in the furnace, prevent the optical window 22 from being contaminated, and prevent the carbonization of the single crystal fiber 32, the armored optical fiber 34, and the thermocouple body 42.

[0075] Specifically, in this embodiment, the inert gas filling assembly is used to fill the three channels with argon gas. The flow rate of a single channel is controlled between 0.5 L / min and 2 L / min, and the pressure is controlled between 1.05 and 1.1 times the gas pressure inside the furnace.

[0076] Reference Figure 4 The graphitization furnace includes a furnace wall 100, a sand layer 200, a carbon black layer 300, and an insulation layer 400 arranged sequentially from bottom to top within the furnace wall 100, with the furnace core area 500 embedded in the insulation layer 400. In this embodiment, the composite temperature measurement system is used by inserting a graphite rod 1 obliquely from the top of the graphitization furnace, penetrating the insulation layer 400 and contacting the furnace core area 500.

[0077] Example 2

[0078] Reference Figure 5 This invention provides a temperature measurement method suitable for internally connected graphitization furnaces, using the composite temperature measurement system for internally connected graphitization furnaces described in Example 1:

[0079] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 0℃<T≤1500℃, the temperature value measured by the contact thermocouple temperature measurement subsystem 4 shall be taken as the furnace core temperature.

[0080] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 1500℃<T≤2300℃, the temperature value measured by the contact fiber optic temperature measurement subsystem 3 shall be taken as the furnace core temperature.

[0081] When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 2300℃<T≤3000℃, the temperature value measured by the non-contact colorimetric temperature measurement subsystem 2 shall be taken as the furnace core temperature.

[0082] When the temperatures measured by the three temperature measurement subsystems are in different temperature ranges, the temperature value measured by the contact fiber optic temperature measurement subsystem 3 is taken as the furnace core temperature.

[0083] It should be noted that although the three temperature measurement subsystems have high measurement accuracy within their respective temperature ranges, they can also measure temperature values ​​in other temperature ranges, albeit with lower accuracy. Therefore, when the furnace core temperature is far from the boundary of the temperature range, the temperature values ​​measured by the three temperature measurement subsystems will be in the same temperature range. However, when the furnace core temperature is close to the boundary of the temperature range, the temperatures measured by the three temperature measurement subsystems may be in different temperature ranges. In this case, the temperature value measured by the contact fiber optic temperature measurement subsystem 3 is taken as the furnace core temperature, as it has higher accuracy.

[0084] It should be noted that since the contact thermocouple temperature measurement subsystem 4 and the contact fiber optic temperature measurement subsystem 3 cannot be exposed to extreme high-temperature environments for extended periods, if the graphitization furnace needs to be kept at temperatures above 2300℃ for a long time, the contact fiber optic temperature measurement subsystem 3 and the contact thermocouple temperature measurement subsystem 4 can be removed to avoid structural damage, as the furnace core temperature is based on the temperature measured by the non-contact colorimetric temperature measurement subsystem 2.

[0085] The above are merely specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A composite temperature measurement system suitable for internally serial graphitization furnaces, characterized in that, include: A graphite rod (1) has a first channel (11), a second channel (12) and a third channel (13). All three channels are axial blind holes and their openings extend to the same end face of the graphite rod (1). The graphite rod (1) is used to penetrate the top of the graphitization furnace and contact the furnace core area (500). The depth of the first channel (11) is equal to the depth of the second channel (12) and is greater than the depth of the third channel (13). The first channel (11) is connected to the third channel (13). The side wall of the first channel (11) has a first air inlet (15) that connects to the outside, and the side wall of the second channel (12) has a second air inlet (16) that connects to the outside. A non-contact colorimetric temperature measurement subsystem (2) is arranged based on the first channel (11), the inner wall of the first channel (11) is coated with an emission coating to form an isothermal blackbody cavity (21), and an optical window (22) is sealed at the opening of the first channel (11). The non-contact colorimetric temperature measurement subsystem (2) includes a colorimetric temperature measurement module (23), which is configured to receive radiation from the isothermal blackbody cavity (21) corresponding to the optical window (22). A contact fiber optic temperature measurement subsystem (3) is provided based on the second channel (12). The opening of the second channel (12) is provided with a fiber optic sealing plug (31). The contact fiber optic temperature measurement subsystem (3) includes a single crystal fiber (32), a fiber optic coupler (33), an armored optical fiber (34), and a photoelectric conversion circuit (35). The single crystal fiber (32) is placed in the second channel (12). One end of the single crystal fiber (32) forms a single crystal blackbody cavity (36) and contacts the bottom of the second channel (12). The other end of the single crystal fiber (32) is connected to the armored optical fiber (34) through the fiber optic coupler (33). The armored optical fiber (34) is sealed through the fiber optic sealing plug (31) and connected to the photoelectric conversion circuit (35). A contact thermocouple temperature measurement subsystem (4) is provided based on the third channel (13). A thermocouple sealing plug (41) is provided at the opening of the third channel (13). The contact thermocouple temperature measurement subsystem (4) includes a thermocouple body (42), a constant temperature bath (43), and a compensating wire (44). The thermocouple body (42) passes through the thermocouple sealing plug (41). The high-temperature end of the thermocouple body (42) contacts the bottom of the third channel (13). The low-temperature end of the thermocouple body (42) is placed in the constant temperature bath (43) and led out through the compensating wire (44). The host computer (5) is connected to the colorimetric temperature measurement module (23), photoelectric conversion circuit (35) and compensation wire (44) to calculate the real-time temperature of each temperature measurement subsystem. An inert gas filling assembly is connected to both the first air inlet (15) and the second air inlet (16) and is used to fill the three channels with inert gas.

2. The composite temperature measurement system for an internally serial graphitization furnace according to claim 1, characterized in that, The outer wall of the graphite rod (1) is provided with an anti-oxidation and anti-carburization protective layer (14).

3. The composite temperature measurement system for an internally serial graphitization furnace according to claim 2, characterized in that, The antioxidant and anti-carburization protective layer (14) is a silicon carbide layer or a composite coating consisting of a pyrolytic carbon transition layer and a silicon carbide layer.

4. The composite temperature measurement system for an internally serial graphitization furnace according to claim 1, characterized in that, The emission coating is a yttrium-stabilized zirconia coating or a silicon carbide coating.

5. The composite temperature measurement system for an internally serial graphitization furnace according to claim 1, characterized in that, The optical window (22) is a sapphire window.

6. The composite temperature measurement system for an internally serial graphitization furnace according to claim 1, characterized in that, The single-crystal optical fiber (32) is a sapphire single-crystal optical fiber (32), and the single-crystal blackbody cavity (36) is a single-crystal magnesium oxide blackbody cavity.

7. The composite temperature measurement system for an internally serial graphitization furnace according to claim 1, characterized in that, The thermocouple body (42) is a tungsten-rhenium thermocouple, and the surface of the tungsten-rhenium thermocouple wire is coated with an anti-oxidation coating.

8. A temperature measurement method suitable for an internally connected graphitization furnace, characterized in that, Temperature measurement is performed using the composite temperature measurement system for internally serial graphitization furnaces as described in any one of claims 1 to 7: When the temperature values ​​measured by the three temperature measurement subsystems are all in the temperature range of 0℃<T≤1500℃, the temperature value measured by the contact thermocouple temperature measurement subsystem (4) shall be taken as the furnace core temperature. When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 1500℃<T≤2300℃, the temperature value measured by the contact fiber optic temperature measurement subsystem (3) shall be taken as the furnace core temperature. When the temperature values ​​measured by the three temperature measurement subsystems are all within the temperature range of 2300℃<T≤3000℃, the temperature value measured by the non-contact colorimetric temperature measurement subsystem (2) shall be taken as the furnace core temperature. When the temperatures measured by the three temperature measurement subsystems are in different temperature ranges, the temperature value measured by the contact fiber optic temperature measurement subsystem (3) is taken as the furnace core temperature.

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