A laboratory constant temperature bath device and method for thermometer calibration

Abstract

The present invention belongs to the technical field of temperature sensor calibration equipment, and particularly relates to a laboratory constant temperature bath device and method for thermometer calibration, including a molten salt constant temperature bath, a molten salt heating bath, a molten salt low temperature bath, and a molten salt recovery bath; the molten salt heating bath is used to transport liquid-phase molten salt with a temperature of T min to the molten salt low temperature bath and transport liquid-phase molten salt with a temperature of T max to the molten salt constant temperature bath; the molten salt low temperature bath is used to transport liquid-phase molten salt with a temperature of T min to the molten salt constant temperature bath, and the molten salt recovery bath is used to receive the liquid-phase molten salt transported by the molten salt constant temperature bath; two-way valves are respectively provided in the corresponding liquid-phase molten salt transport pipelines between the molten salt heating bath and the molten salt low temperature bath, between the molten salt heating bath and the molten salt constant temperature bath, between the molten salt low temperature bath and the molten salt constant temperature bath, and between the molten salt constant temperature bath and the molten salt recovery bath. The transport mode of the liquid-phase molten salt is through pressure difference or height potential difference, and this technical solution improves the test efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature sensor calibration equipment, and particularly relates to a laboratory constant temperature bath device and method for thermometer calibration. Background Art

[0002] For the verification and calibration of temperature measuring devices in the range of 180 - 550°C, high-purity molten salt is generally used as the heat conduction medium in the laboratory. Under the environment where the laboratory ambient temperature is 15 - 35°C and the humidity does not exceed 85%RH, after all the solid salt substances in the molten salt constant temperature bath are melted by the heater and temperature control device, the stirrer and temperature control device are used to make the temperature of the liquid molten salt in the working area reach the set value, and the temperature fluctuation in the working area is maintained at 0.05°C / 10min, and the temperature uniformity is 0.10°C. The temperature measuring devices in the range of 180 - 550°C are calibrated and inspected with high-temperature liquid molten salt as the heat conduction medium, in the order of decreasing from the high temperature point.

[0003] The melting point of high-purity molten salt is 142 - 148°C, and the boiling point is 680°C. Molten salt is a melt composed of metal cations and non-metal anions, which is in a solid state under standard temperature and atmospheric pressure, and in a liquid phase when the temperature exceeds the melting point. High-temperature molten salt has an extraordinary dissolving ability for other substances, so molten salt is commonly used as a solvent. Most molten salts have good thermal stability within a certain temperature range.

[0004] Part 4 of the National Metrology Technical Specification JJF 1030 - 2023 Technical Performance Test Specification for Constant Temperature Baths for Temperature Calibration shows the typical structure of the constant temperature baths currently used in the laboratory, as shown in the appendix Figure 1 As shown, the way to heat the heat conduction medium is to use a heater, and the way to cool the heat conduction medium is to use a refrigeration tube for refrigeration.

[0005] For the currently used constant temperature baths in the laboratory with molten salt as the heat conduction medium, the existing problems include:

[0006] (1) The heat conduction process itself required for refrigeration using a cooling device and heating using a heating device takes a relatively long time, which makes the test waiting time long and the test efficiency low. In addition, the stability and volatility of the temperature of the heat conduction medium depend on the heating, cooling, and stirring effects, and the adjustment time required to meet the technical performance requirements of the constant temperature bath is relatively long. In the case where both the temperature adjustment efficiency and effect are not ideal, the current operation method of the laboratory molten salt constant temperature bath can only choose to first heat the high-purity molten salt to 600°C and then gradually cool it by natural cooling.

[0007] (2)If the stirring fins and the stirring shaft are in direct contact with the high-temperature molten salt liquid, the high-temperature heat will be conducted to the stirring motor shaft, and the stirring motor is prone to failure due to heat, especially the stirring motors of the molten salt heating tank and the molten salt constant temperature tank have the highest failure frequency, resulting in poor operating reliability of the molten salt constant temperature tank system. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to make up for the deficiencies of the prior art and provide a laboratory constant temperature tank device and method for thermometer calibration.

[0009] To solve the above technical problems, the technical solution of the present invention is as follows:

[0010] A laboratory constant temperature tank device for thermometer calibration, including a molten salt constant temperature tank, a rotating socket plate is provided on the top of the molten salt constant temperature tank, a fixed thermometer A and several thermometer sockets are provided on the rotating socket plate, the fixed thermometer A is connected to a multi-channel temperature measuring instrument, a liquid level gauge A, a stirring paddle A and a working area are arranged inside the molten salt constant temperature tank, both the multi-channel temperature measuring instrument and the liquid level gauge A are connected to a controller; the stirring paddle A is driven by a motor A, and the operation of the motor A is controlled by the controller; the working area is located directly below the rotating socket plate, and the temperature measuring part of the fixed thermometer A is located in the working area; it also includes a molten salt heating tank, a molten salt low-temperature tank and a molten salt recovery tank; a molten salt heater, a stirring paddle C and a fixed thermometer C are arranged in the molten salt heating tank for storing and heating molten salt, and the stirring paddle C is driven by a motor C; a liquid level gauge B is arranged in the molten salt low-temperature tank, and the liquid level gauge B is connected to the controller; the molten salt heating tank is used to transport liquid-phase molten salt with a temperature of T min to the molten salt low-temperature tank and transport liquid-phase molten salt with a temperature of T max to the molten salt constant temperature tank, 160 °C ≤ T min <T jmin <T jmax <T max ≤ 600 °C, T jmin is the lowest calibration test temperature point of the thermometer to be detected, and T jmax is the highest calibration test temperature point of the thermometer to be detected; the molten salt low-temperature tank is used to transport liquid-phase molten salt with a temperature of T min to the molten salt constant temperature tank, and the molten salt recovery tank is used to receive the liquid-phase molten salt transported by the molten salt constant temperature tank; two-way valves are respectively arranged in the corresponding liquid-phase molten salt delivery pipelines between the molten salt heating tank and the molten salt low-temperature tank, between the molten salt heating tank and the molten salt constant temperature tank, between the molten salt low-temperature tank and the molten salt constant temperature tank, and between the molten salt constant temperature tank and the molten salt recovery tank, and the operations of each two-way valve and the motor C are controlled by the controller; the transportation method of the liquid-phase molten salt is through pressure difference or height potential difference.

[0011] Further, it further includes a stepped bracket which, from top to bottom in terms of height, successively includes a first layer, a second layer, a third layer, and a fourth layer. The molten salt heating tank is placed on the first layer, the molten salt low-temperature tank is placed on the second layer, the molten salt constant-temperature tank is placed on the third layer, and the molten salt recovery tank is placed on the fourth layer. The liquid-phase molten salt is transported by means of a height potential difference.

[0012] Further, in the corresponding liquid-phase molten salt transport pipelines between the molten salt heating tank and the molten salt low-temperature tank, between the molten salt heating tank and the molten salt constant-temperature tank, between the molten salt low-temperature tank and the molten salt constant-temperature tank, and between the molten salt constant-temperature tank and the molten salt recovery tank, there are respectively provided a molten salt valve C, a molten salt valve D, a molten salt valve B, and a molten salt valve A. The molten salt valve C, the molten salt valve D, the molten salt valve B, and the molten salt valve A are all two-way valves and their operations are all controlled by a controller.

[0013] Further, the molten salt recovery tank transports liquid-phase molten salt to the molten salt heating tank through a molten salt pump and pipe F, and the operation of the molten salt pump is controlled by a controller.

[0014] Further, a stirring paddle B is provided in the molten salt low-temperature tank. The stirring paddle B includes a stirring shaft B and stirring wings B. The rotation of the stirring shaft B is driven by a motor B, and the operation of the motor B is controlled by a controller.

[0015] Further, a partition is provided between the working area and the stirring paddle A.

[0016] Further, the vent holes on the molten salt constant-temperature tank, the molten salt heating tank, the molten salt low-temperature tank, and the molten salt recovery tank are respectively connected to a two-way solenoid valve A, a two-way solenoid valve C, a two-way solenoid valve B, and a two-way solenoid valve D. The operations of the two-way solenoid valve A, the two-way solenoid valve C, the two-way solenoid valve B, and the two-way solenoid valve D are all controlled by a controller.

[0017] Further, it further includes a shaft connection unit which includes a heat insulation pad and a pair of shaft connection members arranged face to face. The shaft connection members include cylindrical shaft sleeves and flanges welded to the ends of the shaft sleeves. The heat insulation pad is clamped between the flanges of the two shaft connection members arranged face to face, and the flanges of the two shaft connection members are fixedly connected by bolts; the output shaft of the motor A and the stirring paddle A, and the output shaft of the motor C and the stirring paddle C are both fixedly connected through the shaft connection unit.

[0018] A method for calibrating a thermometer, using the laboratory constant-temperature tank device for calibrating a thermometer as described above, includes the following steps:

[0019] S1: Add an appropriate amount of molten salt to the molten salt heating tank, make the molten salt heater work to heat the molten salt, and at the same time, make the stirring paddle C stir the molten salt; when the temperature sent by the fixed thermometer C is T min , make the molten salt heater stop working;

[0020] S2: Transport the molten salt at temperature T from the molten salt heating tank to the molten salt low-temperature tankmin For the liquid-phase molten salt, when the liquid level height sent by the liquid level gauge B reaches the set value, stop transporting the liquid-phase molten salt from the molten salt heating tank to the molten salt low-temperature tank;

[0021] S3: Operate the molten salt heater to heat the molten salt. When the temperature sent by the fixed thermometer C is T max stop operating the molten salt heater;

[0022] S4: Transport the liquid-phase molten salt at temperature T max from the molten salt heating tank to the molten salt constant-temperature tank. When the liquid level height sent by the liquid level gauge A reaches the set value h1, stop transporting the liquid-phase molten salt from the molten salt heating tank to the molten salt constant-temperature tank;

[0023] S5: Operate the stirring paddle A to stir the molten salt; transport the liquid-phase molten salt at temperature T min from the molten salt low-temperature tank to the molten salt constant-temperature tank. When the liquid level height sent by the liquid level gauge A reaches the set value H, stop transporting the liquid-phase molten salt from the molten salt low-temperature tank to the molten salt constant-temperature tank; H = h1 + h2, (H - H max ) / H max ≥20%, H max is the height value corresponding to the maximum capacity of the molten salt constant-temperature tank (19);

[0024]

[0025] where i is the temperature measurement point label of the detected thermometer from high to low, and T i is the temperature value of the i-th measurement point;

[0026] S6: Compare the temperature value T s sent by the current fixed thermometer A with T i ,

[0027] If T s - T i > 0, then intermittently transport the liquid-phase molten salt at temperature T min from the molten salt low-temperature tank to the molten salt constant-temperature tank until Ts = T i and stop transporting the liquid-phase molten salt from the molten salt low-temperature tank to the molten salt constant-temperature tank;

[0028] If T s - T i < 0, then intermittently transport the liquid-phase molten salt at temperature T max from the molten salt heating tank to the molten salt constant-temperature tank until Ts = T i and stop transporting the liquid-phase molten salt from the molten salt heating tank to the molten salt constant-temperature tank;

[0029] S7: Test the temperature fluctuation and uniformity of the molten salt in the molten salt thermostat according to the specification. After the temperature fluctuation and uniformity meet the requirements, the controller issues a reminder of "It is possible to start the calibration inspection at the i-th temperature point".

[0030] S8: The inspector inserts the thermometer specimen to be tested into the thermometer jack and extends it into the working area for calibration inspection.

[0031] S9: After the inspection is completed, control the transfer of the liquid-phase molten salt from the molten salt thermostat to the molten salt recovery tank. When the liquid level height sent by the liquid level gauge A reaches the set value h1, stop the transfer of the liquid-phase molten salt from the molten salt thermostat to the molten salt recovery tank.

[0032] S10: Let i = i + 1, conduct the calibration inspection at the next temperature point, and repeat steps S5 - S9.

[0033] Further, T min = 160 °C, T max = 600 °C.

[0034] The beneficial effects that the present invention can achieve are as follows:

[0035] (1) Abandon the direct cooling and heating methods of the molten salt in the thermostat, and adopt the method of neutralizing hot and cold molten salts in the liquid phase, which greatly shortens the waiting time for the molten salt thermostat to cool down and meet the requirements of temperature fluctuation and uniformity, and improves the test efficiency.

[0036] (2) Increase the distance between the stirring shaft and the motor shaft. The stirring shaft and the motor shaft are rigidly connected face to face through two shaft connectors respectively. A high-temperature heat insulation pad is provided at the face-to-face position of the two shaft connectors to prevent heat from being conducted from the stirring shaft to the motor shaft. At the same time, heat dissipation holes are provided on the outer periphery of the shaft connector. When the stirring shaft and the motor shaft rotate synchronously, the heat on the stirring shaft cannot be effectively conducted to the motor shaft due to the centrifugal force generated by the two rows of rotating heat dissipation holes above it. Through these heat insulation and air cooling measures, it is ensured that the stirring motor will not malfunction due to heat and affect the normal operation of the system. Description of the Drawings

[0037] Figure 1 is the typical structure of the thermostat in the technical performance test specification of the thermostat for temperature calibration.

[0038] Figure 2 is the top view of the embodiment of the present invention.

[0039] Figure 3 is Figure 2 the A - A cross-sectional view of

[0040] Figure 4 is the left view of the embodiment of the present invention.

[0041] Figure 5 It is the main sectional view of the molten salt constant temperature tank in the embodiment of the present invention.

[0042] Figure 6 It is the main sectional view of the molten salt heating tank in the embodiment of the present invention.

[0043] Figure 7 It is the main sectional view of the molten salt low temperature tank in the embodiment of the present invention.

[0044] Figure 8 It is the main sectional view of the molten salt recovery tank in the embodiment of the present invention.

[0045] Figure 9 It is the three-dimensional view of the shaft connecting piece in the embodiment of the present invention.

[0046] Figure 10 It is the main sectional view of the shaft connecting piece in the embodiment of the present invention.

[0047] In the figure: 1 - ground, 2 - step support, 3 - pipe A, 4 - molten salt valve A, 5 - pipe B, 6 - sealing material, 7 - stirring shaft A, 8 - partition board, 9 - heat insulation and thermal insulation material, 10 - slope bottom surface A, 11 - workbench, 12 - controller, 13 - multi-channel temperature measuring instrument, 14 - working area, 15 - lower measuring point horizontal plane, 16 - middle measuring point horizontal plane, 17 - upper measuring point horizontal plane, 18 - molten salt liquid level A, 19 - molten salt constant temperature tank, 20 - cover A, 21 - plug, 22 - rotating jack plate, 23 - fixed thermometer A, 24 - movable thermometer A, 25 - liquid level gauge A, 26 - two-way solenoid valve A, 27 - stirring fin A, 28 - bracket A, 29 - motor A, 30 - pipe C, 31 - pipe D, 32 - molten salt valve B, 33 - pipe E, 34 - slope bottom surface B, 35 - stirring fin B, 36 - molten salt liquid level B, 37 - molten salt low temperature tank, 38 - fixed thermometer B, 39 - cover B, 40 - liquid level gauge B, 41 - stirring shaft B, 42 - bracket B, 43 - motor B, 44 - two-way solenoid valve B, 45 - pipe J, 46 - molten salt valve C, 47 - molten salt heater, 48 - stirring fin C, 49 - molten salt liquid level C, 50 - molten salt heating tank, 51 - cover C, 52 - fixed thermometer C, 53 - liquid level gauge C, 54 - stirring shaft C, 55 - substrate, 56 - pressing ring, 57 - sealing ring, 58 - key, 59 - shaft connecting piece, 591 - shaft sleeve, 5911 - heat dissipation hole, 5912 - keyway, 592 - flange; 60 - heat insulation pad, 61 - bracket C, 62 - horizontal top plate, 63 - motor C, 64 - shaft C, 65 - two-way solenoid valve C, 66 - pipe F, 67 - recessed hole, 68 - suction port, 69 - slope surface C, 70 - molten salt liquid level D, 71 - molten salt recovery tank, 72 - molten salt pump, 73 - liquid level gauge D, 74 - two-way solenoid valve D, 75 - cover D, 76 - molten salt valve D, 77 - pipe G, 78 - pipe H;

[0048] 93 - Stirring paddle, 94 - Refrigeration pipe, 95 - Heater, 96 - Temperature controller, 97 - Thermometer jack, 98 - Temperature - controlling platinum resistance, 99 - Stirring motor. Detailed implementation mode

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings and the detailed implementation mode.

[0050] A laboratory constant - temperature bath device for thermometer calibration, including a stepped support 2, a molten - salt constant - temperature bath 19, a molten - salt heating bath 50, a molten - salt low - temperature bath 37, a molten - salt recovery bath 71, a workbench 11, a controller 12 and a multi - channel temperature measuring instrument 13. The controller 12 is a display PLC controller. Heat - insulating and heat - preserving materials 9 are provided outside the molten - salt constant - temperature bath 19, the molten - salt heating bath 50, the molten - salt low - temperature bath 37 and the molten - salt recovery bath 71. The stepped support 2 is used to be placed on the ground 1. The workbench 11 is fixedly connected to the stepped support 2. The controller 12 and the multi - channel temperature measuring instrument 13 are placed on the workbench 11.

[0051] As Figure 3 shown, the stepped support 2 successively includes a first layer, a second layer, a third layer and a fourth layer from top to bottom in height. The molten - salt heating bath 50 is placed on the first layer, the molten - salt low - temperature bath 37 is placed on the second layer, the molten - salt constant - temperature bath 19 is placed on the third layer, and the molten - salt recovery bath 71 is placed on the fourth layer.

[0052] As Figure 5 shown, a cover A20, a liquid - level gauge A25 and a rotating jack plate 22 are installed on the top of the molten - salt constant - temperature bath 19. The liquid - level gauge A25 is used to detect the height of the molten - salt liquid level A18. An air - vent hole A is also provided on the top of the molten - salt constant - temperature bath 19. A two - way solenoid valve A26 is installed on the air - vent hole A. The action of the two - way solenoid valve A26 is controlled by the controller 12. The rotating jack plate 22 is provided with a fixed thermometer A23 and 8 thermometer jacks. Each thermometer jack is equipped with a plug - and - unplug - convenient plug 21. The thermometer jacks are used to plug in a movable thermometer A24 and the thermometer to be detected. The fixed thermometer A23 is connected to the multi - channel temperature measuring instrument 13. Both the multi - channel temperature measuring instrument 13 and the liquid - level gauge A25 are connected to the controller 12. Inside the molten - salt constant - temperature bath 19, there are a stirring paddle A and a working area 14. A partition 8 is provided between the working area 14 and the stirring paddle A. The working area 14 is located directly below the rotating jack plate 22. The temperature - measuring part of the fixed thermometer A23 is located in the working area 14. The stirring paddle A includes a stirring shaft A7 and several stirring vanes A27. The stirring shaft A7 is coaxially and fixedly connected to the output shaft of a motor A29 through a shaft - connecting unit. The shaft - connecting unit is located outside the molten - salt constant - temperature bath 19. The motor A29 is fixedly installed on a bracket A28. The action of the motor A29 is controlled by the controller 12.

[0053] The shaft connection unit includes a heat insulation pad 60 and a pair of shaft connectors 59 arranged face to face. The shaft connector 59 includes a cylindrical shaft sleeve 591 and a flange 592 welded to the end of the shaft sleeve 591. The heat insulation pad 60 is clamped between the flanges 592 of the two shaft connectors 59 arranged face to face. The flanges 592 of the two shaft connectors 59 are fixedly connected by bolts. A keyway 5912 is provided on the shaft sleeve 591. The keyway 5912 of the upper shaft connector 59 in the shaft connection unit is connected to the stirring shaft A7 through a key 58, and the keyway 5912 of the lower shaft connector 59 is connected to the output shaft of the motor A29 through a key. In order to further improve the heat dissipation effect, 4 heat dissipation holes 5911 are circumferentially arrayed on the outer periphery of the shaft sleeve 591.

[0054] A molten salt heater 47 is provided at the bottom of the molten salt heating tank 50, and a cover C51, a fixed thermometer C52 and a liquid level gauge C53 are installed at the top. The liquid level gauge C53 is used to detect the height of the molten salt liquid level C49. Both the fixed thermometer C52 and the liquid level gauge C53 are connected to the controller 12. An air vent C is also provided at the top of the molten salt heating tank 50, and a two-way solenoid valve C65 is installed on the air vent C. The action of the two-way solenoid valve C65 is controlled by the controller 12. A stirring paddle C is further provided in the molten salt heating tank 50. The stirring paddle C is used to stir the molten salt. The stirring paddle C includes a stirring shaft C54 and a plurality of stirring fins C48. The stirring fins C48 are coaxially and fixedly connected to the output shaft C64 of the motor C63 through a shaft connection unit (the connection method is the same as that of "the stirring shaft A7 is coaxially and fixedly connected to the output shaft of the motor A29 through a shaft connection unit"). The shaft connection unit is located outside the molten salt heating tank 50. The motor C63 is fixedly installed on the horizontal top plate 62 of the bracket C61. The base plate 55 of the bracket C61 is fixedly connected to the molten salt heating tank 50. A sealing ring 57 is provided at the rotating connection of the stirring shaft C54 and the molten salt heating tank 50. The retaining ring 56 and the base plate 55 jointly clamp and fix the sealing ring 57. The retaining ring 56 and the base plate 55 are fixedly connected by screws. The action of the motor C63 is controlled by the controller 12.

[0055] At the top of the low-temperature molten salt tank 37, a cover B39 and a liquid level gauge B40 are installed. The liquid level gauge B40 is used to detect the height of the molten salt liquid level B, and the liquid level gauge B40 is connected to the controller 12. An air vent B is also provided at the top of the low-temperature molten salt tank 37. A two-way solenoid valve B44 is installed on the air vent B, and the operation of the two-way solenoid valve B44 is controlled by the controller 12. A stirring paddle B is also provided inside the low-temperature molten salt tank 37. The stirring paddle B is used to stir the molten salt. The stirring paddle B includes a stirring shaft B41 and stirring vanes B35. The stirring shaft B41 is coaxially and fixedly connected to the output shaft of the motor B43 through a shaft connection unit (the connection method is the same as that of "the stirring shaft A7 is coaxially and fixedly connected to the output shaft of the motor A29 through a shaft connection unit"), and the shaft connection unit is located outside the low-temperature molten salt tank 37. The motor B43 is fixedly installed on the top of the bracket B42, and the bracket B42 is fixedly connected to the low-temperature molten salt tank 37. A fixed thermometer B38 is also fixedly provided at the top of the low-temperature molten salt tank 37. The fixed thermometer B38 is used to measure the temperature of the molten salt in the low-temperature molten salt tank 37, and the fixed thermometer B38 is connected to the controller 12. The operation of the motor B43 is controlled by the controller.

[0056] At the top of the molten salt recovery tank 71, a cover D75 and a liquid level gauge D73 are installed. The liquid level gauge D73 is used to detect the height of the molten salt liquid level D70, and the liquid level gauge D73 is connected to the controller 12. An air vent D is also provided at the top of the molten salt recovery tank 71. A two-way solenoid valve D74 is installed on the air vent D, and the operation of the two-way solenoid valve D74 is controlled by the controller 12. A ramp surface C69 is provided at the bottom of the inner cavity of the molten salt recovery tank 71, and the ramp surface C69 extends to the recessed hole 67.

[0057] The suction port 68 of the molten salt pump 72 extends into the recessed hole 67. The liquid outlet of the molten salt pump 72 is connected to the inner cavity of the molten salt heating tank 50 through a pipe F66. The molten salt heating tank 50 is connected to the inner cavity of the low-temperature molten salt tank 37 through a pipe H78, a molten salt valve C46, and a pipe J45 to transport the molten salt using the height potential difference. The molten salt heating tank 50 is connected to the inner cavity of the molten salt constant temperature tank 19 through a pipe G77, a molten salt valve D76, and a pipe C30 to transport the molten salt using the height potential difference. The low-temperature molten salt tank 37 is connected to the inner cavity of the molten salt constant temperature tank 19 through a pipe E33, a molten salt valve B32, and a pipe D31 to transport the molten salt using the height potential difference. The molten salt constant temperature tank 19 is connected to the inner cavity of the molten salt recovery tank 71 through a pipe B5, a molten salt valve A4, and a pipe A3 to transport the molten salt using the height potential difference. The molten salt valve C46, the molten salt valve D76, the molten salt valve B32, and the molten salt valve A4 are all two-way valves, and their operations are all controlled by the controller 12. The molten salt heating tank 50 is used to transport liquid-phase molten salt with a temperature of T min = 160 °C to the low-temperature molten salt tank 37 and transport liquid-phase molten salt with a temperature of T max = 600 °C to the molten salt constant temperature tank 19 (160 °C ≤ T min <T jmin <Tjmax <T max ≤600 °C, where T jmin is the lowest calibration test temperature point of the thermometer to be detected, and T jmax is the highest calibration test temperature point of the thermometer to be detected); the molten salt low-temperature tank 37 is used to convey the liquid-phase molten salt with a temperature of T min = 160 °C to the molten salt constant-temperature tank 19, and the molten salt recovery tank 71 is used to receive the liquid-phase molten salt conveyed by the molten salt constant-temperature tank 19.

[0058] The bottom of the inner cavity of the molten salt constant-temperature tank 19 is provided with a sloping bottom surface A10, and the liquid inlet of the pipe B5 is arranged at the lowest point of the sloping bottom surface A10. The bottom of the inner cavity of the molten salt low-temperature tank 37 is provided with a sloping bottom surface B34, and the liquid inlet of the pipe E33 is arranged at the lowest point of the sloping bottom surface B34.

[0059] Sealing materials 6 are provided at the joints of the above-mentioned pipes and the corresponding tanks.

[0060] The liquid level gauges A25, B40, C53 and D73 are all radar liquid level gauges.

[0061] The fixed thermometer A23, the movable thermometer A24, the fixed thermometer B38 and the fixed thermometer C52 are all quartz sleeve standard platinum resistance thermometers.

[0062] The molten salt valves C46, D76, B32 and A4 and the two-way joints used at the joints are all arranged obliquely downward to avoid the retention of molten salt in each pipeline as much as possible after the test.

[0063] The method for calibrating a thermometer using this embodiment:

[0064] Includes the following steps:

[0065] S1: Add an appropriate amount of molten salt to the molten salt heating tank 50, make the molten salt heater 47 work to heat the molten salt, and at the same time, make the stirring paddle C stir the molten salt; when the temperature sent by the fixed thermometer C52 is T min = 160 °C, make the molten salt heater 47 stop working;

[0066] S2: Convey the liquid-phase molten salt with a temperature of T min = 160 °C from the molten salt heating tank 50 to the molten salt low-temperature tank 37, and stop conveying the liquid-phase molten salt from the molten salt heating tank 50 to the molten salt low-temperature tank 37 when the liquid level height sent by the liquid level gauge B40 reaches the set value;

[0067] S3: Make the molten salt heater 47 work to heat the molten salt, and when the temperature sent by the fixed thermometer C52 is T max = 600 °C, make the molten salt heater 47 stop working;

[0068] S4: Transfer the molten salt in liquid phase with a temperature of T max = 600 °C from the molten salt heating tank 50 to the molten salt thermostat 19. When the liquid level height sent by the liquid level gauge A25 reaches the set value h1, stop transferring the molten salt in liquid phase from the molten salt heating tank 50 to the molten salt thermostat 19;

[0069] S5: Make the stirring paddle A stir the molten salt; transfer the molten salt in liquid phase with a temperature of T min from the molten salt low-temperature tank 37 to the molten salt thermostat 19. When the liquid level height sent by the liquid level gauge A25 reaches the set value H, stop transferring the molten salt in liquid phase from the molten salt low-temperature tank 37 to the molten salt thermostat 19; H = h1 + h2, (H - H max ) / H max ≥ 20%, H max is the height value corresponding to the maximum capacity of the molten salt thermostat 19;

[0070]

[0071] where i is the temperature measurement point label of the detected thermometer from high to low, and T i is the temperature value of the i-th measurement point;

[0072] S6: Compare the temperature value T s sent by the current fixed thermometer A23 with T i ,

[0073] if T s - T i > 0, then intermittently transfer the molten salt in liquid phase with a temperature of T min from the molten salt low-temperature tank 37 to the molten salt thermostat 19 until Ts = T i and then stop transferring the molten salt in liquid phase from the molten salt low-temperature tank 37 to the molten salt thermostat 19;

[0074] if T s - T i < 0, then intermittently transfer the molten salt in liquid phase with a temperature of T max from the molten salt heating tank 50 to the molten salt thermostat 19 until Ts = T i and then stop transferring the molten salt in liquid phase from the molten salt heating tank 50 to the molten salt thermostat 19;

[0075] S7: Test the temperature volatility and uniformity of the molten salt in the molten salt thermostat 19 according to the specification. When the temperature volatility and uniformity meet the requirements, the controller issues a reminder of "Calibration inspection of the i-th temperature point can start";

[0076] Test of temperature volatility: Read the value at 10s intervals and record 61 data in total. The temperature volatility is the difference between the maximum temperature value and the minimum temperature value.

[0077] Test of temperature uniformity:

[0078] First, insert the fixed thermometer A23 to a depth of 1 / 2 in the working area 14, fix its temperature measuring part at the reference position o on the middle measuring point horizontal plane 16. Then insert the movable thermometer A24 into the working area 14, fix its temperature measuring part at the position a on the upper measuring point horizontal plane 17. Subtract the average value of the readings of the fixed thermometer A23 from the average value of the readings of the movable thermometer A24 to obtain the temperature difference Δt of point a relative to point o. a-0 . Similarly, obtain the temperature differences Δt of points b, c, and d on the upper measuring point horizontal plane 17 relative to point o. b-0 、Δt c-0 、Δt d-0 . Then, calculate the arithmetic mean of the temperature differences of points a, b, c, and d on the upper measuring point horizontal plane 17 relative to point o to obtain the temperature difference Δt of the upper measuring point horizontal plane. u =max(Δt a-0 ,Δt b-0 ,Δt c-0 ,Δt d-0 ) - min(Δt a-0 ,Δt b-0 ,Δt c-0 ,Δt d-0 ).

[0079] Similarly, first measure the temperature differences Δt of points e, f, g, and h on the lower measuring point horizontal plane 15 relative to point o. e-0 、Δt f-0 、Δt g-0 、Δt h-0 , and then calculate the arithmetic mean of the temperature differences of points e, f, g, and h on the lower measuring point horizontal plane 15 relative to point o to obtain the temperature difference Δt of the lower measuring point horizontal plane. l =max(Δt e-0 ,Δt f-0 ,Δt g-0 ,Δt h-0 ) - min(Δt e-0 ,Δt f-0 ,Δt g-0 ,Δt h-0 ).

[0080] The horizontal temperature difference is: Δt = max(Δt u ,Δt l ).

[0081] The maximum temperature difference is:

[0082] δ t = max(Δt a-0 ,Δt b-0 ,Δt c-0 ,Δtd-0 , Δt e-0 , Δt f-0 , Δt g-0 , Δt h-0 ) - min(Δt a-0 , Δt b-0 , Δt c-0 , Δt d-0 , Δt e-0 , Δt f-0 , Δt g-0 , Δt h-0 )。

[0083] S8: The inspector inserts the thermometer specimen to be tested into the thermometer jack and extends it into the working area 14 for calibration inspection;

[0084] S9: After the inspection is completed, control the molten salt constant temperature bath 19 to transport the liquid-phase molten salt into the molten salt recovery tank 71. When the liquid level height sent by the liquid level gauge A25 reaches the set value h1, stop transporting the liquid-phase molten salt from the molten salt constant temperature bath 19 to the molten salt recovery tank 71;

[0085] S10: Let i = i + 1, conduct the calibration inspection at the next temperature point, and repeat steps S5 - S9.

[0086] After the test is completed, turn the molten salt valve C46 and the molten salt valve D76 to the closed state, turn the molten salt valve B32 and the molten salt valve A4 to the open state, start the molten salt pump 72, so that all the molten salt in the molten salt low-temperature tank 37 flows out into the molten salt constant temperature bath 19, all the molten salt in the molten salt constant temperature bath 19 flows out into the molten salt recovery tank 71, and all the molten salt in the molten salt recovery tank 71 is pumped into the molten salt heating tank 50.

[0087] The slope surface C69 at the bottom of the inner cavity of the molten salt recovery tank 71, the slope bottom surface A10 at the bottom of the inner cavity of the molten salt constant temperature bath 19, and the slope bottom surface B34 at the bottom of the inner cavity of the molten salt low-temperature tank 37. The existence of the slope surfaces in these three tanks and the depression hole 67 at the bottom of the molten salt recovery tank 71 enables the liquid-phase molten salt to be recovered more thoroughly.

[0088] Table 1 Material Table of this Embodiment

[0089]

Claims

1. A laboratory constant temperature bath device for thermometer calibration, comprising a molten salt constant temperature bath (19). A rotating socket plate (22) is provided on the top of the molten salt constant temperature bath (19). A fixed thermometer A (23) and a number of thermometer sockets are provided on the rotating socket plate (22). The fixed thermometer A (23) is connected to a multi-channel temperature measuring instrument (13). A liquid level gauge A (25), a stirring paddle A and a working area (14) are provided inside the molten salt constant temperature bath (19). Both the multi-channel temperature measuring instrument (13) and the liquid level gauge A (25) are connected to a controller; the stirring paddle A is driven by a motor A (29), and the operation of the motor A (29) is controlled by the controller; the working area (14) is located directly below the rotating socket plate (22), and the temperature measuring part of the fixed thermometer A (23) is located in the working area (14); The characteristics are: It also includes a molten salt heating tank (50), a molten salt low-temperature tank (37) and a molten salt recovery tank (71); a molten salt heater (47), a stirring paddle C and a fixed thermometer C (52) are provided in the molten salt heating tank (50) for storing and heating molten salt, and the stirring paddle C is driven by a motor C (63); a liquid level gauge B (40) is provided in the molten salt low-temperature tank (37), and the liquid level gauge B (40) is connected to the controller; the molten salt heating tank (50) is used to transport liquid-phase molten salt with a temperature of T min to the molten salt low-temperature tank (37) and transport liquid-phase molten salt with a temperature of T max to the molten salt constant-temperature tank (19), where 160°C ≤ T min <T jmin <T jmax <T max ≤ 600°C, T jmin is the lowest calibration inspection temperature point of the thermometer to be detected, and T jmax is the highest calibration inspection temperature point of the thermometer to be detected; the molten salt low-temperature tank (37) is used to transport liquid-phase molten salt with a temperature of T min to the molten salt constant-temperature tank (19), and the molten salt recovery tank (71) is used to receive the liquid-phase molten salt transported by the molten salt constant-temperature tank (19); two-way valves are respectively provided in the corresponding liquid-phase molten salt transport pipelines between the molten salt heating tank (50) and the molten salt low-temperature tank (37), between the molten salt heating tank (50) and the molten salt constant-temperature tank (19), between the molten salt low-temperature tank (37) and the molten salt constant-temperature tank (19), and between the molten salt constant-temperature tank (19) and the molten salt recovery tank (71), and the actions of each two-way valve and the motor C (63) are controlled by the controller; the transport mode of the liquid-phase molten salt is through pressure difference or height potential difference; In the corresponding liquid-phase molten salt delivery pipelines between the molten salt heating tank (50) and the molten salt low-temperature tank (37), between the molten salt heating tank (50) and the molten salt constant temperature bath (19), between the molten salt low-temperature tank (37) and the molten salt constant temperature bath (19), and between the molten salt constant temperature bath (19) and the molten salt recovery tank (71), molten salt valves C (46), molten salt valves D (76), molten salt valves B (32) and molten salt valves A (4) are respectively provided. The molten salt valves C (46), molten salt valves D (76), molten salt valves B (32) and molten salt valves A (4) are all two-way valves and their operations are all controlled by the controller; The vent holes on the molten salt constant temperature bath (19), the molten salt heating tank (50), the molten salt low-temperature tank (37) and the molten salt recovery tank (71) are respectively connected to two-way solenoid valves A (26), two-way solenoid valves C (65), two-way solenoid valves B (44) and two-way solenoid valves D (74). The operations of the two-way solenoid valves A (26), two-way solenoid valves C (65), two-way solenoid valves B (44) and two-way solenoid valves D (74) are all controlled by the controller; It also includes a shaft connection unit. The shaft connection unit includes a heat insulation pad (60) and a pair of shaft connectors (59) arranged face to face. The shaft connectors (59) include a cylindrical shaft sleeve (591) and a flange (592) welded to the end of the shaft sleeve (591). The heat insulation pad (60) is clamped between the flanges (592) of the two shaft connectors (59) arranged face to face. The flanges (592) of the two shaft connectors (59) are fixedly connected by bolts. The output shaft of the motor A (29) and the stirring paddle A, and the output shaft of the motor C (63) and the stirring paddle C are all fixedly connected through the shaft connection unit.

2. The laboratory constant temperature bath device for thermometer calibration according to claim 1, characterized in that: It also includes a stepped bracket (2). The stepped bracket (2) includes a first layer, a second layer, a third layer and a fourth layer in descending order of height. The molten salt heating tank (50) is placed on the first layer, the molten salt low-temperature tank (37) is placed on the second layer, the molten salt constant temperature bath (19) is placed on the third layer, and the molten salt recovery tank (71) is placed on the fourth layer. The liquid-phase molten salt is transported by the height potential difference.

3. The laboratory constant temperature bath device for thermometer calibration according to claim 1, characterized in that: The molten salt recovery tank (71) transports the liquid-phase molten salt to the molten salt heating tank (50) through a molten salt pump (72) and a pipe F (66), and the operation of the molten salt pump (72) is controlled by the controller.

4. The laboratory constant temperature bath device for thermometer calibration according to claim 1, characterized in that: A stirring paddle B is provided in the molten salt low-temperature tank (37). The stirring paddle B includes a stirring shaft B (41) and stirring vanes B (35). The rotation of the stirring shaft B (41) is driven by a motor B (43), and the operation of the motor B (43) is controlled by a controller.

5. The laboratory constant temperature bath device for thermometer calibration according to claim 1, characterized in that: A partition plate (8) is provided between the working area (14) and the stirring paddle A.

6. A method for calibrating a thermometer, characterized in that: Using the laboratory constant temperature tank device for thermometer calibration as described in any one of claims 1-5, the following steps are included: S1: Add an appropriate amount of molten salt into the molten salt heating tank (50), operate the molten salt heater (47) to heat the molten salt, and at the same time, make the stirring paddle C stir the molten salt; when the temperature sent by the fixed thermometer C (52) is T min stop the operation of the molten salt heater (47). S2: Transfer the liquid-phase molten salt with a temperature of T from the molten salt heating tank (50) to the low-temperature molten salt tank (37). When the liquid level height sent by the liquid level gauge B (40) reaches the set value, stop transferring the liquid-phase molten salt from the molten salt heating tank (50) to the low-temperature molten salt tank (37); min ​ S3: Operate the molten salt heater (47) to heat the molten salt. When the temperature sent by the fixed thermometer C (52) is T max stop operating the molten salt heater (47); S4: Transfer liquid-phase molten salt with a temperature of T from the molten salt heating tank (50) to the molten salt thermostat (19). When the liquid level height sent by the liquid level gauge A (25) reaches the set value h1, stop transferring the liquid-phase molten salt from the molten salt heating tank (50) to the molten salt thermostat (19); max When the liquid level height sent by the liquid level gauge A (25) reaches the set value h1, stop transferring the liquid-phase molten salt from the molten salt heating tank (50) to the molten salt thermostat (19); S5: Rotate the stirring paddle A to stir the molten salt; transfer the liquid-phase molten salt with a temperature of T from the low-temperature molten salt tank (37) to the constant-temperature molten salt tank (19). When the liquid level height sent by the liquid level gauge A (25) reaches the set value H, stop transferring the liquid-phase molten salt from the low-temperature molten salt tank (37) to the constant-temperature molten salt tank (19); H = h1 + h2, (H - H min ) / H max ≥ 20%, where H max is the height value corresponding to the maximum capacity of the constant-temperature molten salt tank (19); max ​ ； where i is the label of the temperature measurement point of the thermometer to be detected from high to low, and T i is the temperature value at the i-th measurement point; S6: Compare the temperature value T sent by the current fixed thermometer A (23) s with T i , If T s -T i >0, the molten salt low temperature tank (37) intermittently transports the molten salt with a temperature of T to the molten salt constant temperature tank (19). min Liquid molten salt, to Ts = T i When the temperature of the molten salt is high, the liquid phase molten salt is stopped from being transported from the molten salt low temperature tank (37) to the molten salt constant temperature tank (19); If T s -T i <0, the molten salt heating tank (50) intermittently conveys liquid-phase molten salt at a temperature of T max into the molten salt thermostat (19) until Ts = T i At this time, the conveyance of liquid-phase molten salt from the molten salt heating tank (50) to the molten salt thermostat (19) is stopped; S7: Test the temperature volatility and uniformity of the molten salt in the molten salt constant temperature tank (19) according to the specifications. When the temperature volatility and uniformity meet the requirements, the controller issues a reminder of "the calibration inspection of the i-th temperature point can start". S8: The inspector inserts the thermometer specimen to be tested into the thermometer jack and extends it into the working area (14) for calibration inspection. S9: After the inspection is completed, control the transfer of the liquid-phase molten salt from the molten salt constant temperature tank (19) to the molten salt recovery tank (71). Stop transferring the liquid-phase molten salt from the molten salt constant temperature tank (19) to the molten salt recovery tank (71) when the liquid level height sent by the liquid level gauge A (25) reaches the set value h1. S10: Let i = i + 1, perform the calibration inspection of the next temperature point, and repeat steps S5-S9.

7. The method for calibrating a thermometer according to claim 6, characterized in that: T min = 160 °C, T max = 600 °C.

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