Temperature field test system and method for thermocouple calibration furnace having temperature uniformity block

Abstract

A temperature field test system for a thermocouple calibration furnace (1) having a temperature uniformity block (8). In the system, two ends of the thermocouple calibration furnace (1) are sealed by means of positioning blocks (9); a standard thermocouple (4) is placed in a quartz tube (2), a reference junction of the standard thermocouple (4) is connected to one end of a wire (3) and is then placed in a glass test tube (5), an opening of the glass test tube (5) is sealed, the glass test tube (5) is placed in a reference junction thermostat (6), and the other end of the wire (3) is connected to an electrical measurement device (7); when empty-furnace temperature field test parameters of the thermocouple calibration furnace (1) are to be acquired, the quartz tube (2) axially passes through the thermocouple calibration furnace (1) and the positioning blocks (9); and when temperature field test parameters of the thermocouple calibration furnace (1) having the temperature uniformity block (8) are to be acquired, the temperature uniformity block (8) is arranged in the thermocouple calibration furnace (1), and an end portion of the quartz tube (2) is inserted into the temperature uniformity block (8). Thus, the placement position of the temperature uniformity block (8) in the thermocouple calibration furnace (1) can be determined, and whether the temperature field of the thermocouple calibration furnace (1) having the temperature uniformity block (8) meets the technical specification requirements is determined. Further disclosed is a temperature field test method for a thermocouple calibration furnace (1) having a temperature uniformity block (8).

Description

A temperature field testing system and method for a thermocouple calibration furnace with a temperature equalizing block

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on March 29, 2024, with application number 2024103785924 and invention name “A testing system and method for the temperature field of a thermocouple calibration furnace with an equalizing block”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of temperature field testing, and relates to a testing system and method, and specifically to a testing system and method for the temperature field of a thermocouple calibration furnace with a temperature-equalizing block. Background Art

[0004] A thermocouple calibration furnace is a constant temperature device used for calibrating low-cost metal thermocouples and armored thermocouples, and is often used for high-temperature measurements. The temperature field performance of a thermocouple calibration furnace plays a crucial role in the calibration of these thermocouples and is a key factor influencing the measurement uncertainty of industrial thermocouple calibration results.

[0005] At present, in the temperature field test of thermocouple calibration furnace, the temperature field test is generally carried out on the empty furnace state, and then the dedicated temperature equalizing block of the thermocouple calibration furnace is directly placed at the geometric center of the thermocouple calibration furnace by default. Then, the PID feedback adjustment of the heating power of the thermocouple calibration furnace is performed according to its temperature control sensor to ensure the stability of temperature control and constant temperature when the load increases after the placement of the temperature equalizing block. However, there is no confirmation of whether the temperature field performance after the placement of the temperature equalizing block can meet the temperature field technical indicators required for carrying out the calibration work of low-cost metal thermocouples and armored thermocouples. In addition, the position of the dedicated temperature equalizing block in the thermocouple calibration furnace is also a key point to ensure that its temperature field can meet the requirements of carrying out the work.

[0006] The location of the dedicated temperature block in the thermocouple calibration furnace and the performance test of the temperature field of the thermocouple calibration furnace with the temperature block are crucial to confirm whether its temperature field can meet the technical index requirements for the calibration of cheap metal thermocouples and armored thermocouples. Therefore, the test of the temperature field of the thermocouple calibration furnace with the temperature block is of great significance for its practical application.

[0007] Summary of the Invention

[0008] The purpose of this application is to overcome the shortcomings of the above-mentioned prior art and provide a testing system and method for the temperature field of a thermocouple calibration furnace with a temperature equalizing block. The system and method can determine the placement position of the temperature equalizing block in the thermocouple calibration furnace and judge whether the temperature field of the thermocouple calibration furnace with the temperature equalizing block meets the technical index requirements.

[0009] To achieve the above-mentioned purpose, the present application discloses a temperature field testing system of a thermocouple calibration furnace with a temperature equalizing block, comprising a thermocouple calibration furnace, a standard thermocouple, a quartz tube, a wire, a glass test tube, a reference end thermostat, and an electrical measuring device;

[0010] Both ends of the thermocouple calibration furnace are sealed by positioning blocks, a standard thermocouple is placed in the quartz tube, a reference end of the standard thermocouple is connected to one end of a wire and then placed in a glass test tube, the tube mouth of the glass test tube is sealed, the glass test tube is placed in a reference end thermostat, and the other end of the wire is connected to an electrical measuring device;

[0011] When used to obtain the empty furnace temperature field test parameters of the thermocouple calibration furnace, the quartz tube passes through the thermocouple calibration furnace and the positioning block in the axial direction;

[0012] When used to obtain temperature field test parameters of a thermocouple calibration furnace with a temperature-averaging block, the thermocouple calibration furnace is provided with a temperature-averaging block, and the end of the quartz tube is inserted into the temperature-averaging block.

[0013] The geometric center of the internal cavity of the temperature-averaging block coincides with the position of the highest temperature point of the hollow furnace temperature field in the thermocouple calibration furnace.

[0014] The number of the standard thermocouples is two.

[0015] The temperature-equalizing block is an annular or socket-type structure.

[0016] The end of the quartz tube is located at the bottom of the inner cavity of the temperature-isolating block.

[0017] The reference end thermostat is an ice-water mixture insulation device for providing a 0°C temperature field.

[0018] Anhydrous ethanol is filled into the glass test tube, and the tube mouth of the glass test tube is blocked by absorbent cotton.

[0019] The length of the glass test tube is greater than 210 mm and less than 250 mm, and the inner diameter is (4-6) mm.

[0020] The electrical measuring device is a dual-channel nanovoltmeter.

[0021] The present application discloses a method for testing the temperature field of a thermocouple calibration furnace with a temperature equalizing block, comprising the following steps:

[0022] 1) Perform temperature field tests in the axial and radial directions in the thermocouple calibration furnace at a constant temperature;

[0023] 2) Use standard thermocouples to test the actual temperature of the temperature field in the furnace;

[0024] 3) Compensate the reference end temperature of the standard thermocouple through the reference end thermostat;

[0025] 4) Collecting the thermoelectromotive force value measured by the standard thermocouple through electrical measuring equipment;

[0026] 5) By measuring various points in the axial direction of the thermocouple calibration furnace, find the position of the highest point of the temperature field, calculate the temperature difference between other points and the highest point, and use this to determine the axial effective working area;

[0027] 6) By measuring each position point in the radial direction of the thermocouple calibration furnace, determine the maximum and minimum values ​​of each position point, and calculate the temperature difference between the maximum and minimum values;

[0028] 7) Based on the empty furnace temperature field test of the thermocouple calibration furnace, find the highest temperature point in the axial direction. Place the temperature block at a position so that the geometric center of the cavity coincides with the highest temperature point. The thermocouple calibration furnace with the temperature block is tested at a constant temperature of 1000°C in the axial and radial directions.

[0029] 8) Compare the measured temperature difference with the technical indicators to determine whether the temperature field of the thermocouple calibration furnace with a temperature equalizing block meets the corresponding technical indicator requirements.

[0030] This application has the following beneficial effects:

[0031] During specific operation of the temperature field testing system and method of the thermocouple calibration furnace with an equalizing temperature block described in the present application, the temperature field test is performed on an empty thermocouple calibration furnace to confirm the position of the highest temperature point in the temperature field; an equalizing temperature block is placed in the thermocouple calibration furnace; when testing the temperature field of the thermocouple calibration furnace with an equalizing temperature block, the temperature difference of each position point in the axial direction and the radial direction is calculated respectively; the measurement results are compared with the technical indicators to determine whether the temperature field of the thermocouple calibration furnace with the equalizing temperature block meets the technical indicator requirements, so as to ensure that the temperature field of the thermocouple calibration furnace with the equalizing temperature block meets the requirements and ensure the accuracy and reliability of the calibration results of low-cost metal thermocouples and armored thermocouples. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a flow chart of Example 3;

[0033] FIG2 is a structural diagram of embodiment 1;

[0034] FIG3 is a structural diagram of the second embodiment.

[0035] Among them, 1 is the thermocouple calibration furnace, 2 is the quartz tube, 3 is the wire, 4 is the standard thermocouple, 5 is the glass test tube, 6 is the reference end thermostat, 7 is the electrical measuring equipment, 8 is the temperature equalizing block, and 9 is the positioning block. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments, and are not intended to limit the scope of disclosure of the present application. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0037] The accompanying drawings illustrate schematic diagrams of the structures of the embodiments disclosed herein. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] Example 1

[0039] 2 , this embodiment is used to obtain the test parameters of the empty furnace temperature field of a thermocouple calibration furnace. The temperature field test system of the thermocouple calibration furnace with a temperature equalizing block described in this application includes a thermocouple calibration furnace 1, a standard thermocouple 4, a quartz tube 2, a wire 3, a glass test tube 5, a reference end thermostat 6, and an electrical measuring device 7;

[0040] Both ends of the thermocouple calibration furnace 1 are blocked by positioning blocks 9, the quartz tube 2 passes through the thermocouple calibration furnace 1 and the positioning block 9 axially, the standard thermocouple 4 is placed in the quartz tube 2, the reference end of the standard thermocouple 4 is connected to one end of the wire 3 and then placed in a glass test tube 5, the tube mouth of the glass test tube 5 is blocked, the glass test tube 5 is placed in a reference end thermostat 6, and the other end of the wire 3 is connected to an electrical measuring device 7. During the test, the thermocouple calibration furnace 1 is in an empty furnace state, and the thermocouple calibration furnace 1 performs a temperature field test to obtain the highest temperature point position of the empty furnace temperature field in the thermocouple calibration furnace 1.

[0041] Example 2

[0042] 3 , this embodiment is used to obtain temperature field test parameters of a thermocouple calibration furnace 1 with a temperature equalizing block 8 ; the temperature field test system of a thermocouple calibration furnace with a temperature equalizing block described in this application includes a thermocouple calibration furnace 1 , a standard thermocouple 4 , a quartz tube 2 , a wire 3 , a glass test tube 5 , a reference end thermostat 6 , and an electrical measuring device 7 ;

[0043] Both ends of the thermocouple calibration furnace 1 are blocked by positioning blocks 9. A temperature-equalizing block 8 is provided in the thermocouple calibration furnace 1. The end of the quartz tube 2 is inserted into the temperature-equalizing block 8. The standard thermocouple 4 is placed in the quartz tube 2. The reference end of the standard thermocouple 4 is connected to one end of the wire 3 and then placed in a glass test tube 5. The opening of the glass test tube 5 is closed. The glass test tube 5 is located in the reference end thermostat 6. The other end of the wire 3 is connected to the electrical measuring device 7.

[0044] In this embodiment, the geometric center of the internal cavity of the temperature-averaging block 8 coincides with the position of the highest temperature point of the hollow furnace temperature field of the thermocouple calibration furnace 1 .

[0045] In this embodiment, the outer diameter of the quartz tube 2 is (6-8) mm, and the inner diameter is (4-6) mm. The end of the quartz tube 2 is located at the bottom of the inner cavity of the temperature-equalizing block 8 .

[0046] In this embodiment, the measuring end of the standard thermocouple 4 is located inside the quartz tube 2 .

[0047] In this embodiment, the number of the standard thermocouples 4 is two, and the standard thermocouples 4 are standard platinum-rhodium 10-platinum thermocouples.

[0048] In this embodiment, the temperature-balancing block 8 is an annular or socket-type structure, and is placed in two ways: at the furnace mouth or at the furnace tail.

[0049] In this embodiment, the electrical measuring device 7 is a dual-channel nanovoltmeter.

[0050] In this embodiment, the reference end thermostat 6 is an ice-water mixture insulation device for providing a temperature field of 0°C.

[0051] In this embodiment, the length of the glass test tube 5 is greater than 210 mm and less than 250 mm, and the inner diameter is (4-6) mm. When in use, the glass test tube 5 is filled with anhydrous ethanol, and the tube mouth of the glass test tube 5 is sealed with absorbent cotton.

[0052] In this embodiment, the temperature field test furnace temperature of the thermocouple calibration furnace 1 is set to 1000°C.

[0053] Example 3

[0054] 1 , the method for testing the temperature field of a thermocouple calibration furnace 1 with a temperature equalizing block 8 described in the present application includes the following steps:

[0055] 1) Thermocouple calibration furnace 1 performs temperature field tests in the axial and radial directions at a constant temperature of 1000°C;

[0056] 2) The standard thermocouple 4 tests the actual temperature of the temperature field in the thermocouple calibration furnace 1;

[0057] 3) The reference end thermostat 6 performs reference end temperature compensation on the standard thermocouple 4;

[0058] 4) The electrical measuring device 7 collects the thermoelectromotive force value measured by the standard thermocouple 4;

[0059] 5) By measuring various points in the axial direction of the thermocouple calibration furnace 1, the highest point of the temperature field is found, and the temperature difference between other points and the highest point is calculated to determine the effective axial working area;

[0060] 6) By measuring each position point in the radial direction of the thermocouple calibration furnace 1, the maximum and minimum values ​​of each position point are determined, and the temperature difference between the maximum and minimum values ​​is calculated;

[0061] 7) Based on the empty furnace temperature field test of the thermocouple calibration furnace 1, the highest temperature point in the axial direction is found. The temperature-averaging block 8 is placed at a position such that the geometric center of the cavity coincides with the highest temperature point. The thermocouple calibration furnace 1 with the temperature-averaging block 8 is subjected to temperature field tests in the axial and radial directions at a constant temperature of 1000°C.

[0062] 8) Compare the measured temperature difference with the technical indicators to determine whether the temperature field of the thermocouple calibration furnace 1 with the temperature equalizing block 8 meets the corresponding technical indicator requirements.

[0063] The specific steps include:

[0064] 1) Measure the furnace length of the thermocouple calibration furnace 1 and calculate the geometric center position of the thermocouple calibration furnace 1.

[0065] 2) Set the operating temperature of thermocouple calibration furnace 1 to 1000°C and start heating.

[0066] 3) Measure the length of the limiting part of the positioning block 9.

[0067] 4) Measure and mark the length from the geometric center position of the measuring end inserted into the thermocouple calibration furnace 1 to the outer limit end of the positioning block 9 on the two standard thermocouples 4 as a reference mark for the length position of the standard thermocouple 4 inserted into the thermocouple calibration furnace 1.

[0068] 5) Make a fixed zero-starting mark on the outer porcelain tubes of the two standard thermocouples 4 at a position with the same length close to the reference end, which is used as a reference mark for axial temperature field measurement. Make a mark every 5 mm from the zero-starting mark to the measuring end and the reference end, marking the coordinate position from -50 mm to 50 mm.

[0069] 6) Install the positioning block 9 into the furnace mouth and the furnace tail end of the thermocouple calibration furnace 1 so that the positioning block 9 is close to the thermocouple calibration furnace 1. The two quartz tubes 2 pass through the two positioning blocks 9 and remain in an axially horizontal state in the thermocouple calibration furnace 1.

[0070] 7) Insert one of the standard thermocouples 4 as a fixed couple into the quartz tube 2 at the center of the thermocouple calibration furnace 1, and insert the other standard thermocouple 4 as a movable couple into the quartz tube 2 at the same horizontal position and parallel to it. Adjust the insertion depth of the two standard thermocouples 4 to the calculated and marked length.

[0071] 8) Restore the reference end thermostat 6 to a temperature of 0°C, add 1 / 4 of the length of anhydrous ethanol to the glass test tube 5, and then insert it into the reference end thermostat 6 through the jack at the upper end of the reference end thermostat 6. The insertion depth is greater than or equal to 150 mm.

[0072] 9) The positive and negative poles of the standard thermocouple 4 are respectively connected to the positive and negative ends of a pair of corresponding wires 3 through a plastic hose. Ensure that the positive and negative poles of the standard thermocouple 4 are in close contact with the positive and negative ends of the wires 3, respectively, without any loose connections or poor contact. Then, the positive and negative ends are respectively inserted into the glass test tube 5 in the reference end thermostat 6. The tube mouth of the glass test tube 5 is blocked with absorbent cotton. The other end of the wire 3 is connected to the electrical measuring device 7, and the ground terminal of the electrical measuring device 7 is grounded.

[0073] 10) After heating the thermocouple calibration furnace 1 to the set temperature point, start timing for 60 minutes, which is the thermal equilibrium waiting time. After the time is up, observe the display value of the electrical measuring device 7. After confirming that the temperature field is stable, start the temperature field test.

[0074] 11) The temperature field test in the thermocouple calibration furnace 1 starts from the geometric center of the axial direction as the 0 o'clock position. The standard thermocouple 4 at the center is a fixed couple. During the test, it is always kept at the 0 o'clock position. Another standard thermocouple 4 at the same horizontal position and parallel is a movable couple. Starting from the 0 o'clock position, according to the marked interval and the moving order of 0mm→50mm→0mm→-50mm→0mm, the temperature field test of each position point is carried out at the interval point. Each position point is stabilized for 3 minutes. The thermoelectromotive force values ​​of the fixed couple and the movable couple are read respectively by the electrical measuring device 7, and the readings are not less than 4 times.

[0075] 12) The temperature field test of the thermocouple calibration furnace 1 in the radial direction is carried out with its geometric center as the 0-point position. The two standard thermocouples 4 are both positioned at the 0-point position by rotating the positioning block 9 in the order of left → up → right → down → right → up → left. The temperature field test of the radial points is carried out in turn. Each radial point is stabilized for 3 minutes. The thermoelectromotive force values ​​of the fixed couple and the movable couple are read respectively by the electrical measuring device 7, and the readings are not less than 4 times.

[0076] 13) Calculate the actual potential value of the positive stroke measurement at each position point in the axial direction as follows:

[0077] Among them, e i is the actual potential value of the standard thermocouple 4 at each position point in the axial direction, is the measured average value of the positive stroke of the moving couple at each position in the axial direction, In order to fix the measured average value of the positive stroke corresponding to each position point during the axial temperature field test, the standard thermocouple 4 is an S-type graduation number, and its nominal potential value at 1000°C is 9.587mV.

[0078] 14) Calculate the actual potential value of the reverse stroke measurement at each position point in the axial direction:

[0079] Among them, e j is the actual potential value of the standard thermocouple 4 at each position point in the axial direction, is the measured average value of the reverse stroke of the moving couple at each position in the axial direction, In order to fix the measured average value of the reverse stroke corresponding to each position point during the axial temperature field test, the standard thermocouple 4 is an S-type graduation number, and its nominal thermoelectric potential value at 1000℃ is 9.587mV.

[0080] 15) Calculate the actual potential value of each position point in the axial direction as follows:

[0081] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction.

[0082] 16) Calculate the highest temperature point of the temperature field at each position in the axial direction: e max =max(e ij )

[0083] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction, e max It is the highest temperature point of the temperature field of the standard thermocouple 4 in the axial direction.

[0084] 17) Calculate the temperature difference between the temperature field at each position point in the axial direction and the highest temperature point:

[0085] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction, e max is the highest temperature point of the temperature field of the standard thermocouple 4 in the axial direction, Δt ij is the temperature difference between the temperature field temperature at each position and the highest point temperature. The standard thermocouple 4 is S-type, and its nominal differential thermoelectric potential value at 1000℃ is 0.01154mV / ℃.

[0086] 18) Determine the effective working temperature field area that meets the requirement of effective uniform temperature field 60mm, and the deviation between the center of the uniform temperature field and the geometric center of the furnace is ≤10mm, that is, the absolute value of the maximum and minimum difference of the temperature difference at each position in the axial direction does not exceed 1℃. The formula is as follows: |max(Δt ij )-min(Δt ij )|≤1℃

[0087] 19) Calculate the difference between the actual potential value of each position point in the radial positive stroke and the center position point:

[0088] Where Δe n is the actual potential difference of the standard thermocouple 4 at each position in the radial positive stroke, is the average value of the measurement of each position point of the moving couple in the radial direction, It is the average value of the measurements of each position point corresponding to the positive stroke of the fixed couple in the radial direction.

[0089] 20) Calculate the difference between the actual potential value of each position point in the radial direction and the center position point:

[0090] Where Δe m is the actual potential difference of each position point of the standard thermocouple 4 in the radial direction of the reverse stroke, is the average value of the measurement of each position point of the moving couple in the radial direction of the reverse stroke, It is the average value of the measurements at each position point corresponding to the radial reverse stroke of the fixed couple.

[0091] 21) Calculate the average value of the actual potential difference at each position point in the radial direction:

[0092] Where Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction, Δe nΔe is the actual potential difference of the standard thermocouple 4 at each position in the radial direction of the positive stroke, m It is the actual potential difference of each position point of the standard thermocouple 4 in the radial reverse stroke.

[0093] 22) Calculate the actual potential difference between the temperature field at each point in the radial direction and the center point as follows:

[0094] Where Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction, Δe n Δe is the actual potential difference of the standard thermocouple 4 at each position in the radial direction of the positive stroke, m It is the actual potential difference of each position point of the standard thermocouple 4 in the radial reverse stroke.

[0095] 23) Calculate the temperature difference between each position point in the radial direction and the temperature field of the center point as follows:

[0096] Where Δt nm is the temperature difference between the temperature field of each position point and the center point of the standard thermocouple 4 in the radial direction, Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction. The standard thermocouple 4 is S-type, and its nominal differential thermoelectric potential value at 1000℃ is 0.01154mV / ℃.

[0097] 25) The absolute value of the maximum and minimum temperature difference at each position in the radial direction does not exceed 1°C. The formula is as follows: |max(Δt nm )-min(Δt nm )|≤1℃

[0098] 26) Confirm whether the empty furnace temperature field test of the thermocouple calibration furnace 1 meets the requirements through the test results of the temperature field in the axial direction and the radial direction. If it meets the requirements, configure the temperature block 8 to perform the temperature field test of the thermocouple calibration furnace 1 with the temperature block 8.

[0099] 27) Adjust the length of the temperature-averaging block 8 placed in the thermocouple calibration furnace 1 so that the geometric center point of its internal cavity coincides with the position of the highest temperature point in the empty furnace temperature field of the thermocouple calibration furnace 1. When the thermocouple calibration furnace 1 is at room temperature, place the temperature-averaging block 8 in the thermocouple calibration furnace 1.

[0100] 28) Measure and mark the length on the two standard thermocouples 4 from the geometric center position inside the cavity where the measuring end is inserted into the temperature-equalizing block 8 to the outer end of the limit block of the temperature-equalizing block 8, which serves as a reference mark for the length position of the standard thermocouple 4 inserted into the thermocouple calibration furnace 1 with the temperature-equalizing block 8.

[0101] 29) According to the position of the furnace mouth limit plug of the temperature equalizing block 8, when the limit plug is at the furnace mouth position, the two quartz tubes 2 pass through the holes of the limit plug of the temperature equalizing block 8 and are inserted into the bottom of the cavity of the temperature equalizing block 8. When the limit plug is at the furnace tail position, the two quartz tubes 2 pass through the holes of the positioning block 9 and are inserted into the bottom of the cavity of the temperature equalizing block 8.

[0102] 30) Insert two standard thermocouples 4 into the quartz tube 2 to a depth equal to the reference mark. Connect the positive and negative poles of the reference end of the standard thermocouple 4 to one end of the wire 3 in sequence. Then insert them into the glass test tube 5 in the reference end thermostat 6. Block the mouth of the glass test tube 5 with absorbent cotton. Connect the other end of the wire 3 to the positive and negative terminals of the potential value of the electrical measuring device 7. The ground terminal of the electrical measuring device 7 is grounded.

[0103] 31) After heating the thermocouple calibration furnace 1 with the temperature-averaging block 8 to the set temperature point 1000, start timing for 60 minutes, which is the thermal equilibrium waiting time. After the time is up, observe the display value of the electrical measuring device 77. After confirming that the temperature field is stable, start the temperature field test.

[0104] 32) The temperature field test of the thermocouple calibration furnace 1 with the temperature-averaging block 8 starts from the highest temperature point of the empty furnace temperature field in the axial direction as the 0-point position. The standard thermocouple 4 at the center is a fixed couple and is always kept at the 0-point position during the test. Another standard thermocouple 4 at the same horizontal position and parallel to it is a movable couple. Starting from the 0-point position, the temperature field test of each position point is carried out at the interval point according to the moving sequence of 0mm→30mm→0mm→-30mm→0mm according to the marked interval. Each point is stabilized for 3 minutes. The thermoelectromotive force values ​​of the fixed couple and the movable couple are read respectively by the electrical measuring device 7, and the readings are not less than 4 times.

[0105] 33) The temperature field test of the thermocouple calibration furnace 1 with the temperature equalizing block 8 is carried out in the radial direction with its geometric center as the 0-point position. The two standard thermocouples 4 are both at the 0-point position and the radial position of the movable couple is rotated in the order of left → up → right → down → right → up → left. The temperature field test of the radial direction points is carried out in sequence. Each radial direction point is stabilized for 3 minutes. The thermoelectromotive force values ​​of the fixed couple and the movable couple are read by the electrical measuring device 7 respectively, and the readings are not less than 4 times.

[0106] 34) Calculate the actual potential value of the positive stroke measurement at each position point in the axial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8:

[0107] Among them, e i is the actual potential value of the standard thermocouple 4 at each position point in the axial direction, is the measured average value of the positive stroke of the moving couple at each position in the axial direction, In order to fix the measured average value of the positive stroke corresponding to each position point during the axial temperature field test, the standard thermocouple 4 is an S-type graduation number, and its nominal potential value at 1000°C is 9.587mV.

[0108] 35) Calculate the actual potential value of the reverse stroke measurement at each position point in the axial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8:

[0109] Among them, e j is the actual potential value of the standard thermocouple 4 at each position point in the axial direction, is the measured average value of the reverse stroke of the moving couple at each position in the axial direction, In order to fix the measured average value of the reverse stroke corresponding to each position point during the axial temperature field test, the standard thermocouple 4 is an S-type graduation number, and its nominal thermoelectric potential value at 1000℃ is 9.587mV.

[0110] 36) Calculate the actual potential value of each position point in the axial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8 as follows:

[0111] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction.

[0112] 37) Calculate the highest temperature point of the temperature field at each position in the axial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8: max =max(e ij )

[0113] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction, e max It is the highest temperature point of the temperature field of the standard thermocouple 4 in the axial direction.

[0114] 38) Calculate the temperature difference between the temperature field at each position in the axial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8 and the highest temperature point:

[0115] Among them, e ij is the actual potential value of the standard thermocouple 4 at each position in the axial direction, e max is the highest temperature point of the temperature field of the standard thermocouple 4 in the axial direction, Δt ij is the temperature difference between the temperature field temperature at each position and the highest point temperature. The standard thermocouple 4 is S-type, and its nominal differential thermoelectric potential value at 1000℃ is 0.01154mV / ℃.

[0116] 39) The thermocouple calibration furnace 1 with the temperature equalizing block 8 is provided with an effective uniform temperature field of 30 mm in the axial direction, that is, an effective working temperature field region where the absolute value of the maximum and minimum temperature differences at each position in the axial direction does not exceed ±0.5°C. The formula is as follows: |max(Δt ij )-min(Δt ij )|≤0.5℃

[0117] 40) Calculate the difference between the actual potential value of each position point in the radial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8 and the center position point:

[0118] Where Δe n is the actual potential difference of the standard thermocouple 4 at each position in the radial positive stroke, is the average value of the measurement of each position point of the moving couple in the radial direction, It is the average value of the measurements of each position point corresponding to the positive stroke of the fixed couple in the radial direction.

[0119] 41) Calculate the difference between the actual potential value of each position point in the radial direction of the reverse stroke of the thermocouple calibration furnace 1 with the temperature equalizing block 8 and the center position point:

[0120] Where Δe m is the actual potential difference of each position point of the standard thermocouple 4 in the radial direction of the reverse stroke, is the average value of the measurement of each position point of the moving couple in the radial direction of the reverse stroke, It is the average value of the measurements at each position point corresponding to the radial reverse stroke of the fixed couple.

[0121] 42) Calculate the average value of the difference in actual potential value at each position point in the radial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8:

[0122] Where Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction, Δe n Δe is the actual potential difference of the standard thermocouple 4 at each position in the radial direction of the positive stroke, m It is the actual potential difference of each position point of the standard thermocouple 4 in the radial reverse stroke.

[0123] 43) Calculate the actual potential difference between the temperature field at each radial position point and the center point of the thermocouple calibration furnace 1 with the temperature equalizing block 8:

[0124] Where Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction, Δen Δe is the actual potential difference of the standard thermocouple 4 at each position in the radial direction of the positive stroke, m It is the actual potential difference of each position point of the standard thermocouple 4 in the radial reverse stroke.

[0125] 44) Calculate the temperature difference between each radial position point and the center point of the thermocouple calibration furnace 1 with the temperature equalizing block 8:

[0126] Where Δt nm is the temperature difference between the temperature field of each position point and the center point of the standard thermocouple 4 in the radial direction, Δe nm is the average value of the actual potential difference of the standard thermocouple 4 at each position in the radial direction. The standard thermocouple 4 is S-type, and its nominal differential thermoelectric potential value at 1000℃ is 0.01154mV / ℃.

[0127] 45) Calculate the absolute value of the maximum and minimum temperature difference of each position in the radial direction of the thermocouple calibration furnace 1 with the temperature equalizing block 8, which does not exceed 0.25°C. The formula is as follows: |max(Δt nm )-min(Δt nm )|≤0.25℃

[0128] 46) Through the test results of the axial and radial temperature fields of the thermocouple calibration furnace 1 with the temperature equalizing block 8, confirm whether the temperature field of the thermocouple calibration furnace 1 with the temperature equalizing block 8 meets the technical index requirements for the development of low-cost metal thermocouples and armored thermocouples, and whether the absolute value of the temperature difference between any two points within 30mm axially in the effective working area is not greater than 0.5℃, and the absolute value of the temperature difference between any two points in the same radial section is not greater than 0.25℃.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A temperature field testing system for thermocouple calibration furnace with a temperature equalizing block, characterized in that: It includes a thermocouple calibration furnace (1), a standard thermocouple (4), a quartz tube (2), a wire (3), a glass test tube (5), a reference end thermostat (6) and an electrical measuring device (7); Both ends of the thermocouple calibration furnace (1) are sealed by positioning blocks (9), a standard thermocouple (4) is placed in the quartz tube (2), a reference end of the standard thermocouple (4) is connected to one end of a wire (3) and then placed in a glass test tube (5), the tube mouth of the glass test tube (5) is sealed, the glass test tube (5) is placed in a reference end thermostat (6), and the other end of the wire (3) is connected to an electrical measuring device (7); When used to obtain the empty furnace temperature field test parameters of the thermocouple calibration furnace, the quartz tube (2) passes through the thermocouple calibration furnace (1) and the positioning block (9) in the axial direction; When used to obtain temperature field test parameters of a thermocouple calibration furnace (1) with a temperature-equalizing block (8), the thermocouple calibration furnace (1) is provided with a temperature-equalizing block (8), and the end of the quartz tube (2) is inserted into the temperature-equalizing block (8).

2. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The geometric center of the internal cavity of the temperature-averaging block (8) coincides with the position of the highest temperature point in the hollow furnace temperature field of the thermocouple calibration furnace (1).

3. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The number of the standard thermocouples (4) is two.

4. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The temperature-equalizing block (8) is an annular or socket-type structure.

5. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The end of the quartz tube (2) is located at the bottom of the internal cavity of the temperature-isolating block (8).

6. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The reference end thermostat (6) is an ice-water mixture insulation device for providing a 0°C temperature field.

7. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: Anhydrous ethanol is filled into the glass test tube (5), and the tube mouth of the glass test tube (5) is blocked by absorbent cotton.

8. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The length of the glass test tube (5) is greater than 210 mm and less than 250 mm, and the inner diameter is (4-6) mm.

9. The temperature field testing system of the thermocouple calibration furnace with a temperature equalizing block according to claim 1, characterized in that: The electrical measuring device (7) is a dual-channel nanovoltmeter.

10. A method for testing the temperature field of a thermocouple calibration furnace with a temperature equalizing block, characterized in that: The following steps are involved: 1) performing temperature field tests in the axial direction and the radial direction on the thermocouple calibration furnace (1) at a constant temperature; 2) testing the actual temperature of the temperature field in the thermocouple calibration furnace (1) by using a standard thermocouple (4); 3) performing reference end temperature compensation on the standard thermocouple (4) through the reference end thermostat (6); 4) collecting the thermoelectromotive force value measured by the standard thermocouple (4) through the electrical measuring device (7); 5) by measuring various positions in the axial direction of the thermocouple calibration furnace (1), finding the position of the highest point of the temperature field, calculating the temperature difference between other positions and the highest point, and thereby determining the axial effective working area; 6) measuring each position point in the radial direction of the thermocouple calibration furnace (1), determining the maximum value and the minimum value of each position point, and calculating the temperature difference between the maximum value and the minimum value; 7) According to the empty furnace temperature field test of the thermocouple calibration furnace (1), the highest temperature point in the axial direction is found, and the temperature-averaging block (8) is placed at a position such that the geometric center of the cavity coincides with the highest temperature point. The thermocouple calibration furnace (1) with the temperature-averaging block (8) is subjected to temperature field tests in the axial direction and the radial direction at a constant temperature of 1000° C.; 8) Comparing the measured temperature difference with the technical index to determine whether the temperature field of the thermocouple calibration furnace (1) with the temperature-averaging block (8) meets the corresponding technical index requirements.

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