Thermocouple verification furnace tube

Abstract

The utility model discloses a thermocouple verification furnace tube, which relates to the technical field of thermocouple calibration, and comprises an outer furnace tube, a temperature equalizing block, a measuring end positioning block, a measuring section temperature adjusting block, a temperature control end positioning block and a temperature control section temperature adjusting block, the temperature equalizing block is arranged in the outer furnace tube, the temperature equalizing block is provided with a temperature control couple hole, the temperature control couple hole is used for inserting a temperature control couple, and the temperature control couple is arranged in the outer furnace tube. A measuring end furnace mouth and a temperature control end furnace mouth are respectively arranged at the two ends of the outer furnace tube, and a measuring end positioning block and a temperature control end positioning block are respectively arranged at the two ends of the outer furnace tube; after the thermocouple verification furnace runs for a long time, according to the axial temperature field of the thermocouple verification furnace, the number of the measuring section temperature adjusting blocks and the number of the temperature control section temperature adjusting blocks can be flexibly configured, heat transfer between the outer furnace tube and the outside is adjusted, the temperature field in the temperature equalizing block is improved, and the uncertainty of the thermocouple calibration result is reduced; the service cycle of the verification furnace is prolonged, and the influence of maintenance on calibration work is reduced; asbestos is not used, so that the working environment of verification personnel is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of thermocouple calibration, and particularly relates to a thermocouple verification furnace tube. Background Art

[0002] A thermocouple is a thermometer made of two conductors of different materials based on the Seebeck effect. A thermocouple verification furnace (hereinafter referred to as the verification furnace) is an electric heating device that provides a heat source for thermocouple calibration. It mainly consists of a furnace tube, heating elements, a heat-insulating layer, a shell, etc. The heating elements are wound outside the furnace tube, a temperature control thermocouple is arranged inside the furnace tube, and the temperature of the furnace tube is adjusted by the temperature controller according to the deviation between the temperature measured by the temperature control thermocouple and the set value by adjusting the power of the heating elements.

[0003] Thermocouple verification furnaces are divided into base metal thermocouple verification furnaces (hereinafter referred to as base metal couple furnaces) and sheathed thermocouple verification furnaces (hereinafter referred to as sheathed couple furnaces) according to the form of the thermocouples to be verified, and the configured temperature equalizing blocks are in cup shape and porous form respectively.

[0004] The temperature field performance of the verification furnace is an important factor affecting the calibration error and uncertainty of thermocouples. In the national metrological technical specification "JJF 1262-2010 Calibration Specification for Sheathed Thermocouples" and "JJF 1637-2017 Calibration Specification for Base Metal Thermocouples", it is required that the verification furnace be equipped with a temperature equalizing block, and within the axial 30 mm of the effective working area, the absolute value of the temperature difference between any two points shall not be greater than 0.5 °C.

[0005] Due to factors such as furnace chamber wear, aging of heating elements and heat-insulating layer during the use of the verification furnace, the temperature field of the verification furnace cannot meet the requirements of the calibration specification, and it needs to be returned to the factory for repair, replacing the worn and aged components. The repair cycle is long, delaying the normal thermocouple calibration work.

[0006] The prior art (such as Chinese Patent Publication No. CN 212871554 U A Thermocouple Verification Furnace and Chinese Patent Publication No. CN 212871554 U A Thermocouple Calibration Device) mainly makes the temperature field of the thermocouple verification furnace more uniform through structural, technological and material innovations when manufacturing the thermocouple verification furnace, without involving the temperature field improvement and life extension technology during the use of the verification furnace. Therefore, we propose a thermocouple verification furnace tube to extend the service life of the verification furnace. Summary of the Invention

[0007] The purpose of the utility model is to solve the defects existing in the prior art, and a thermocouple verification furnace tube is proposed.

[0008] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0009] A thermocouple calibration furnace tube, comprising an outer furnace tube, a temperature equalizing block, a measuring end positioning block, a measuring section temperature adjusting block, a control end positioning block, and a control section temperature adjusting block. The temperature equalizing block is placed inside the outer furnace tube. A control thermocouple hole is provided on the temperature equalizing block for inserting a control thermocouple. Measuring end furnace openings and control end furnace openings are respectively arranged at both ends of the outer furnace tube, and a measuring end positioning block and a control end positioning block are respectively arranged. The measuring section temperature adjusting block is arranged between the temperature equalizing block and the measuring end positioning block and is close to the temperature equalizing block. The control section temperature adjusting block is arranged between the temperature equalizing block and the control end positioning block and is close to the temperature equalizing block. The numbers of the measuring section temperature adjusting block and the control section temperature adjusting block are set according to the axial temperature field inside the temperature equalizing block;

[0010] A groove is formed on the outer wall of the outer furnace tube, and a heating wire is wound in the groove. The power of the heating wire is adjusted by a temperature controller according to the difference between the temperature measured by the control thermocouple and the set temperature, so that the temperature inside the furnace tube is stabilized at the set value.

[0011] The temperature equalizing block is in the form of a cup or a porous shape and is made of a high-temperature resistant alloy; the measuring section temperature adjusting block is in the form of a ring or a porous shape, the measuring end positioning block is in the form of a ring or a porous shape, the control section temperature adjusting block and the control end positioning block are both in the form of a single hole, and the measuring end positioning block, the measuring section temperature adjusting block, the control end positioning block, and the control section temperature adjusting block are all made of high-aluminum clay, corundum, or mullite materials.

[0012] Through holes are formed on the measuring section temperature adjusting block, and the center lines of the through holes coincide with the center lines of the holes formed on the temperature equalizing block. The number of the through holes is not more than that of the holes formed on the temperature equalizing block, and the diameters of the through holes are not larger than those of the holes formed on the temperature equalizing block;

[0013] The number, position, and diameter of the through holes formed on the measuring end positioning block are the same as those on the measuring section temperature adjusting block.

[0014] One through hole is formed on the control section temperature adjusting block. Among them, the center line of the through hole coincides with the center line of the control thermocouple hole, and the diameter of the through hole is not less than the diameter of the control thermocouple and not larger than the diameter of the control thermocouple hole;

[0015] The number, position, and diameter of the through holes formed on the control end positioning block are the same as those on the control section temperature adjusting block.

[0016] A using method of a thermocouple calibration furnace tube, the method comprising the following steps:

[0017] Installed inside the furnace during the manufacture of the thermocouple calibration furnace, including an outer furnace tube, a temperature equalizing block, a measuring end positioning block, and a control end positioning block;

[0018] During the use process, adjust the configured numbers of the measuring section temperature adjusting block and the control section temperature adjusting block according to the temperature field change inside the temperature equalizing block, so that the temperature field meets the requirements of the metrological technical specifications;

[0019] When the temperature in the isothermal block decreases monotonically towards the bottom of the hole, a temperature control section temperature regulating block should be set; when the temperature in the isothermal block increases monotonically towards the bottom of the hole, a measurement section temperature regulating block should be set; when the temperature in the isothermal block decreases towards both the furnace mouth of the measurement end and the furnace mouth of the temperature control end, a measurement section temperature regulating block and a temperature control section temperature regulating block should be set simultaneously;

[0020] After adding each measurement section temperature regulating block or temperature control section temperature regulating block, the temperature field inside the isothermal block should be re-measured until the temperature field inside the isothermal block meets the requirements of the metrological technical specifications.

[0021] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0022] The present utility model can flexibly configure the number of measurement section temperature regulating blocks and temperature control section temperature regulating blocks according to the axial temperature field after the long-term operation of the thermocouple verification furnace, adjust the heat transfer between the outer furnace tube and the outside world, improve the temperature field inside the isothermal block, reduce the uncertainty of the thermocouple calibration result; extend the service life of the verification furnace and reduce the impact of maintenance on the calibration work; do not use asbestos and improve the working environment of the verification personnel. Description of the Drawings

[0023] The drawings are used to provide a further understanding of the present utility model, and constitute a part of the specification. Together with the embodiments of the present utility model, they are used to explain the present utility model and do not constitute a limitation to the present utility model.

[0024] Figure 1 is a schematic structural diagram of the sheathed thermocouple verification furnace tube in the prior art;

[0025] Figure 2 is a schematic structural diagram of the sheathed thermocouple verification furnace tube according to an embodiment of the present utility model;

[0026] Figure 3 In (a) is a schematic front sectional structure diagram of the measurement section temperature regulating block in the form of multiple holes of the present utility model;

[0027] Figure 3 In (b) is a schematic left sectional structure diagram of the measurement section temperature regulating block in the form of multiple holes of the present utility model;

[0028] Figure 4 In (a) is a schematic front sectional structure diagram of the single-hole temperature control section temperature regulating block of the present utility model;

[0029] Figure 4 In (b) is a schematic left sectional structure diagram of the single-hole temperature control section temperature regulating block of the present utility model;

[0030] Figure 5 is a schematic structural diagram of the base metal thermocouple verification furnace tube in the prior art;

[0031] Figure 6Schematic diagram of the structure of the base metal thermocouple calibration furnace tube according to another embodiment of the present utility model;

[0032] Figure 7 In (a), it is a schematic diagram of the main view cross-section structure of the annular measurement end positioning block of the present utility model;

[0033] Figure 7 In (b), it is a schematic diagram of the right view cross-section structure of the annular measurement end positioning block of the present utility model;

[0034] Figure 8 In (a), it is a schematic diagram of the main view cross-section structure of the annular measurement section temperature control block of the present utility model;

[0035] Figure 8 In (b), it is a schematic diagram of the left view cross-section structure of the annular measurement section temperature control block of the present utility model;

[0036] Figure 9 It is a flow chart of the usage method of the thermocouple calibration furnace tube.

[0037] In the figure: 1. Outer furnace tube; 2. Temperature equalizing block; 3. Temperature control thermocouple hole; 4. Measurement end furnace opening; 5. Temperature control end furnace opening; 6. Temperature control end positioning block; 7. Measurement end positioning block; 8. Measurement section temperature control block; 9. Temperature control section temperature control block. Specific implementation manners

[0038] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model;

[0039] Embodiment 1

[0040] Please refer to Figure 1-4 , a thermocouple calibration furnace tube, including an outer furnace tube 1, a temperature equalizing block 2, a measurement end positioning block 7, a measurement section temperature control block 8, a temperature control end positioning block 6, and a temperature control section temperature control block 9. The temperature equalizing block 2 is placed inside the outer furnace tube 1. The temperature equalizing block 2 is provided with a temperature control thermocouple hole 3 for inserting a temperature control thermocouple. The two ends of the outer furnace tube 1 are respectively provided with a measurement end furnace opening 4 and a temperature control end furnace opening 5 and are respectively provided with a measurement end positioning block 7 and a temperature control end positioning block 6. The measurement section temperature control block 8 is arranged between the temperature equalizing block 2 and the measurement end positioning block 7 and is close to the temperature equalizing block 2. The temperature control section temperature control block 9 is arranged between the temperature equalizing block 2 and the temperature control end positioning block 6 and is close to the temperature equalizing block 2. The numbers of the measurement section temperature control block 8 and the temperature control section temperature control block 9 are set according to the axial temperature field inside the temperature equalizing block 2.

[0041] A groove is formed on the outer wall of the outer furnace tube 1, and a heating wire is wound in the groove. The power of the heating wire is adjusted by the temperature controller according to the difference between the temperature measured by the temperature control thermocouple and the set temperature, so as to keep the temperature inside the furnace tube stable at the set value.

[0042] The isothermal block 2 is in the form of a cup or a porous structure and is made of a high-temperature resistant alloy; the temperature-adjusting block 8 of the measuring section is in the form of a ring or a porous structure, the positioning block 7 of the measuring end is in the form of a ring or a porous structure, the temperature-adjusting block 9 of the temperature-control section and the positioning block 6 of the temperature-control end are both in the form of a single hole, and the positioning block 7 of the measuring end, the temperature-adjusting block 8 of the measuring section, the positioning block 6 of the temperature-control end and the temperature-adjusting block 9 of the temperature-control section are all made of high-aluminum clay, corundum or mullite materials.

[0043] Further, through holes are formed in the temperature-adjusting block 8 of the measuring section, the center line of the through holes coincides with the center line of the holes formed in the isothermal block 2, the number of the through holes is not more than that of the holes formed in the isothermal block 2, and the diameter of the through holes is not larger than that of the holes formed in the isothermal block 2.

[0044] Further, the number, positions and diameters of the through holes formed in the positioning block 7 of the measuring end are the same as those of the through holes formed in the temperature-adjusting block 8 of the measuring section.

[0045] Further, one through hole is formed in the temperature-adjusting block 9 of the temperature-control section, wherein the center line of the through hole coincides with the center line of the thermocouple hole 3, and the diameter of the through hole is not less than the diameter of the thermocouple and not larger than the diameter of the thermocouple hole 3.

[0046] Further, the number, positions and diameters of the through holes formed in the positioning block 6 of the temperature-control end are the same as those of the through holes formed in the temperature-adjusting block 9 of the temperature-control section.

[0047] A using method of a thermocouple verification furnace tube, the method comprising the following steps: being installed in a furnace during the manufacture of the thermocouple verification furnace, and comprising an outer furnace tube 1, an isothermal block 2, a positioning block 7 of a measuring end and a positioning block 6 of a temperature-control end;

[0048] During use, adjusting the configured numbers of the temperature-adjusting block 8 of the measuring section and the temperature-adjusting block 9 of the temperature-control section according to the temperature field change in the isothermal block 2 so that the temperature field meets the requirements of the metrological technical specifications;

[0049] When the temperature in the isothermal block 2 monotonically decreases towards the bottom of the hole, the temperature-adjusting block 9 of the temperature-control section should be provided; when the temperature in the isothermal block 2 monotonically increases towards the bottom of the hole, the temperature-adjusting block 8 of the measuring section should be provided; when the temperature in the isothermal block 2 decreases towards both the measuring-end furnace mouth 4 and the temperature-control-end furnace mouth 5, the temperature-adjusting block 8 of the measuring section and the temperature-adjusting block 9 of the temperature-control section should be provided simultaneously;

[0050] After adding one temperature-adjusting block 8 of the measuring section or one temperature-adjusting block 9 of the temperature-control section, the temperature field in the isothermal block 2 should be re-measured until the temperature field in the isothermal block 2 meets the requirements of the metrological technical specifications.

[0051] Specifically: Figure 1The figure shows a schematic diagram of the structure of the sheathed thermocouple verification furnace tube in the prior art. The length of the outer furnace tube 1 is 600 mm, and the inner diameter is 40 mm. The total length of the porous temperature equalizing block 2 placed inside the outer furnace tube 1 is 100 mm. The inner diameter of the central hole opened on the porous temperature equalizing block 2 is 8 mm, and 8 holes with an inner diameter of 6 mm are evenly distributed on the circumference with a diameter of 24 mm on the same side. The depth of the holes opened on this side is 80 mm. On the other side of the porous temperature equalizing block 2, there is an eccentric temperature control thermocouple hole 3 with an inner diameter of 8 mm and a depth of 15 mm. The central axis is 9 mm away from the outer wall. Inside the temperature control end furnace mouth 5, asbestos is tightly stuffed or a temperature control end positioning block 6 is provided to reduce heat dissipation to the outside.

[0052] The method of stuffing asbestos inside the temperature control end furnace mouth 5 has great drawbacks. The asbestos is baked by the high temperature inside the furnace tube for a long time, which will become loose, the heat preservation performance will decline, a large amount of dust will be generated, and irreversible damage will be caused to the human lungs.

[0053] Figure 1 During the operation of the sheathed thermocouple verification furnace in the laboratory, every year, according to the national metrological technical specification JJF 1184-2007 "Technical Specification for Temperature Field Testing of Thermocouple Verification Furnaces", the temperature field inside its furnace tube is tested at 1000 °C. After 3 years of operation, the axial temperature field results are shown in the following table:

[0054] Position / 10mm 5 4 3 2 1 0 -1 -2 -3 Temperature difference / °C -1.9 -1.2 -0.8 -0.5 -0.2 0.0 0.3 0.6 0.1

[0055] In the table, the central position of the outer furnace tube 1 is 0, the position close to the measuring end furnace mouth 4 is positive, and the position close to the temperature control end furnace mouth 5 is negative. The deviation between the temperature at each position point and the temperature at the 0 position is the temperature difference at each position point. If the temperature at the position point is higher than the temperature at the 0 position, the temperature difference is positive; otherwise, it is negative.

[0056] As can be seen from the table, the maximum temperature difference within 30 mm axially from the bottom of the hole in the axial temperature field of the sheathed thermocouple verification furnace is 0.6 °C, which no longer meets the requirement of not being greater than 0.5 °C. The axial temperature gradually decreases from position -2 to the measuring end furnace mouth 4, and the axial temperature significantly decreases from position -2 to the bottom of the porous temperature equalizing block 2. In the embodiment of the present invention, a measuring end positioning block 7, a measuring section temperature regulating block 8, and a temperature control section temperature regulating block 9 are arranged to reduce heat dissipation and improve the temperature field.

[0057] The temperature fields at different holes at position -2 are measured as shown in the following table:

[0058] Position / hole 1 2 3 4 5 6 7 8 0 Temperature difference / °C 0.12 0.10 0.04 0.08 -0.03 -0.10 -0.07 -0.11 0.00

[0059] In the table, the positions of the holes are numbered clockwise (left view), and the 0 position represents the central hole.

[0060] As can be seen from the table, the maximum temperature difference between the holes is 0.23 °C, which meets the requirement of not being greater than 0.25 °C in the calibration specification.

[0061] Figure 2-4 The figure shows a structural schematic diagram of the armored thermocouple verification furnace tube, the temperature adjustment block in the measurement section in a porous form, and the temperature adjustment block in the single-hole temperature control section of the present utility model; the length of the measurement end positioning block 7 is 55 mm, the length of the temperature adjustment block 8 in the measurement section is 50 mm, and the diameters, positions, and numbers of the through holes provided on the measurement end positioning block 7 and the temperature adjustment block 8 in the measurement section are the same as those on the porous uniform temperature block 2; the length of the temperature adjustment block 9 in the temperature control section is 50 mm, and the diameters and positions of the through holes provided on the temperature adjustment block 9 in the temperature control section are the same as those on the temperature control thermocouple hole 3; the temperature control end positioning block 6, the measurement end positioning block 7, the temperature adjustment block 8 in the measurement section, and the temperature adjustment block 9 in the temperature control section are all made of mullite fiber.

[0062] According to Figure 9 A method for using a thermocouple verification furnace tube of the present utility model finally sets 1 piece each of the measurement end positioning block 7, the temperature adjustment block 8 in the measurement section in a porous form, and the temperature adjustment block 9 in the single-hole form of the temperature control section. At 1000 °C, the temperature field of the verification furnace in the embodiment Figure 2 is tested, and the measured axial temperature field is as shown in the following table:

[0063] Position / 10mm 5 4 3 2 1 0 -1 -2 -3 Temperature difference / °C -1.3 -0.8 -0.5 -0.3 -0.1 0.0 0.1 0.4 0.2

[0064] The temperature field at position -2 of different holes is measured as shown in the following table:

[0065] Position / hole 1 2 3 4 5 6 7 8 0 Temperature difference / °C 0.10 0.09 0.04 0.06 0.01 -0.07 -0.05 -0.09 0.00

[0066] It can be seen from the measurement results that the maximum temperature difference within 30 mm axially from the bottom of the hole is 0.4 °C, and the maximum temperature difference between holes is 0.19 °C, meeting the requirements of the national metrological technical specification, and the temperature field of the armored thermocouple verification furnace is significantly improved.

[0067] Embodiment 2

[0068] Please refer to Figure 5-8 , another embodiment provided by the present utility model, which is similar to Embodiment 1, but specifically: Figure 5 The figure shows a structural schematic diagram of a base metal thermocouple verification furnace tube of the prior art. The length of the outer furnace tube 1 is 600 mm, the inner diameter is 40 mm, and there are grooves on the outer wall of the outer furnace tube 1, and heating wires are wound in the grooves; the total length of the cup-shaped uniform temperature block 2 placed in the outer furnace tube 1 is 100 mm, the inner diameter of the hole provided on one side of the cup-shaped uniform temperature block 2 is 30 mm, and the depth is 80 mm; the inner diameter of the temperature control thermocouple hole 3 on the other side of the cup-shaped uniform temperature block 2 is 8 mm, and the depth is 15 mm, and the central axis of the hole coincides with the central axis of the cup-shaped uniform temperature block 2; asbestos is tightly stuffed in the temperature control end furnace mouth 5, or a temperature control end positioning block 6 is provided to reduce the heat dissipation to the outside.

[0069] According to the national metrological technical specification JJF 1184-2007 "Technical Specification for Temperature Field Test of Thermocouple Verification Furnaces" for the operating Figure 5The axial temperature field of the base metal thermocouple calibration furnace shown is tested at 1000°C, and the measured results are as follows in the table:

[0070]

[0071] In the table, the center position of the furnace tube is 0, the position closer to the measuring end furnace mouth 4 side is positive, and the position closer to the temperature control end furnace mouth 5 side is negative. The deviation of the temperature at each position point from the temperature at the 0 position is the temperature difference at each position point. If the temperature at the position point is higher than the temperature at the 0 position, the temperature difference is positive; otherwise, it is negative.

[0072] As can be seen from the table, the highest temperature point of the base metal thermocouple calibration furnace is at position -2. The minimum temperature difference within the axial 30 mm of the effective working area is 0.6°C, located at positions (1 to -2), not meeting the requirement of not being greater than 0.5°C.

[0073] The longitudinal section temperature field measured at position -2 is as follows in the table:

[0074] Position / - Up Right Down Left 0 Temperature difference / °C 0.13 0.03 -0.10 -0.08 0.00

[0075] In the table, the 0 position represents the geometric center of the longitudinal section.

[0076] As can be seen from the table, the maximum radial temperature difference is 0.23°C, meeting the requirement of not being greater than 0.25°C.

[0077] Figure 6-8 Shown is a schematic structural diagram of the base metal thermocouple calibration furnace tube according to another embodiment of the present invention; the length of the annular measurement section temperature regulating block 8 is 50 mm; the length of the single-hole temperature control section temperature regulating block 9 is 50 mm; the lengths of the measurement end positioning block 7 and the temperature control end positioning block 6 are both 55 mm; the diameters of the through holes opened on the annular measurement section temperature regulating block 8 and the measurement end positioning block 7 are the same as those on the cup-shaped temperature equalizing block 2, and the diameters and radial positions of the holes opened on the single-hole temperature control section temperature regulating block 9 and the temperature control end positioning block 6 are the same as those of the temperature control thermocouple hole 3. The temperature control end positioning block 6, the measurement end positioning block 7, the measurement section temperature regulating block 8, and the temperature control section temperature regulating block 9 are all made of corundum.

[0078] According to Figure 9 A method for using a thermocouple calibration furnace tube of the present invention, successively adding the measurement section positioning block 7, successively and alternately adding the measurement section temperature regulating block 8 and the temperature control section temperature regulating block 9, and measuring the temperature field inside the temperature equalizing block 2 of the calibration furnace after each addition until the temperature field meets the requirements of the metrological technical specifications. Finally, 4 annular measurement section temperature regulating blocks 8, 4 single-hole temperature control section temperature regulating blocks 9, and 1 measurement end positioning block 7 are added. At 1000°C, Figure 6 The axial temperature field of the base metal thermocouple calibration furnace shown is tested, and the measured axial temperature field is as follows in the table:

[0079]

[0080]

[0081] The temperature field at the bottom of the hole measured is shown in the following table:

[0082] Position / - Up Right Down Left 0 Temperature difference / °C 0.11 0.03 -0.07 -0.05 0.00

[0083] From the measurement results, it can be seen that the temperature field of the base metal thermocouple calibration furnace has been significantly improved. The minimum temperature difference within 30 mm axially in the effective working area is 0.3 °C, located at positions (0 to -3), and the maximum temperature difference radially is 0.18 °C, meeting the requirements of the national metrological technical specifications.

[0084] In summary, the utility model can flexibly configure the number of temperature adjustment blocks 8 in the measurement section and temperature control blocks 9 according to the temperature field of the thermocouple calibration furnace, reduce the heat transfer between the furnace tube and the outside world, improve the temperature field in the temperature equalizing block 2, and reduce the uncertainty of the thermocouple calibration result; extend the service life of the calibration furnace and reduce the impact of maintenance on the calibration work; without using asbestos, it improves the working environment of the calibration personnel.

Claims

1. A thermocouple calibration furnace tube, comprising an outer furnace tube (1), a temperature equalizing block (2), a measuring end positioning block (7), a measuring section temperature regulating block (8), a temperature control end positioning block (6) and a temperature control section temperature regulating block (9), characterized in that: The temperature-averaging block (2) is placed in the outer furnace tube (1); the temperature-averaging block (2) is provided with a temperature-controlling couple hole (3); the temperature-controlling couple hole (3) is used to insert a temperature-controlling couple; the two ends of the outer furnace tube (1) are respectively provided with a measuring end furnace opening (4) and a temperature-controlling end furnace opening (5); and are respectively provided with a measuring end positioning block (7) and a temperature-controlling end positioning block (6); the measuring section temperature-adjusting block (8) is arranged between the temperature-averaging block (2) and the measuring end positioning block (7) and is close to the temperature-averaging block (2); the temperature-controlling section temperature-adjusting block (9) is arranged between the temperature-averaging block (2) and the temperature-controlling end positioning block (6) and is close to the temperature-averaging block (2); and the number of the measuring section temperature-adjusting blocks (8) and the temperature-controlling section temperature-adjusting blocks (9) is arranged according to the axial temperature field in the temperature-averaging block (2); A groove is formed on the outer wall of the outer furnace tube (1), and a heating wire is wound in the groove. The power of the heating wire is adjusted by a temperature controller according to the difference between the temperature measured by the temperature control couple and the set temperature, so that the temperature in the furnace tube is stabilized at the set value.

2. A thermocouple calibration furnace tube according to claim 1, characterized in that: The temperature-averaging block (2) is cup-shaped or porous and is made of a high-temperature resistant alloy; the measuring section temperature-adjusting block (8) is annular or porous, the measuring end positioning block (7) is annular or porous, the temperature-control section temperature-adjusting block (9) and the temperature-control end positioning block (6) are both single-hole, and the measuring end positioning block (7), the measuring section temperature-adjusting block (8), the temperature-control end positioning block (6) and the temperature-control section temperature-adjusting block (9) are all made of high-alumina clay, corundum or mullite.

3. A thermocouple calibration furnace tube according to claim 2, characterized in that: The measuring section temperature regulating block (8) is provided with a through hole, the center line of the through hole coincides with the center line of the hole provided on the temperature equalizing block (2), the number of the through holes is not more than the number of holes provided on the temperature equalizing block (2), and the diameter of the through hole is not greater than the diameter of the hole provided on the temperature equalizing block (2); The number, position and diameter of the through holes on the measuring end positioning block (7) are consistent with those on the measuring section temperature regulating block (8).

4. A thermocouple calibration furnace tube according to claim 3, characterized in that: A through hole is provided on the temperature control section temperature regulating block (9), wherein the center line of the through hole coincides with the center line of the temperature control couple hole (3), and the diameter of the through hole is not less than the diameter of the temperature control couple and not greater than the diameter of the temperature control couple hole (3); The number, position and diameter of the through holes on the temperature control end positioning block (6) are consistent with those on the temperature control section temperature regulating block (9).

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