A flowmeter calibration device and calibration method

Abstract

This invention relates to a flow meter calibration device and method, belonging to the field of flow metering technology. It includes a medium storage tank, a booster pump, a pressure stabilizing tank, a constant-volume water tank, an air conditioner, a metering pump, a chiller / heater unit, a sampler, a vacuum pump, a flow meter, an orifice plate, a PLC controller, and a hot air drying device. The PLC controller performs detection, alarm, analysis, and interlock control on the device, and receives data such as temperature, pressure, and liquid level. The sampler is used for weighing and measurement to calibrate the density of the tested medium at different temperatures and pressures. Simultaneously, the metering pump measures the CO2 circulation volume per unit time to obtain the volumetric flow rate, which is used to correct the mass flow rate of the tested flow meter. At the same time, all data is uploaded to the PLC controller database in real time to establish isochoric and isodense curves, providing a basis for subsequent calibration of similar flow meters.

Description

Technical Field

[0001] This invention relates to a flow meter calibration device and calibration method, belonging to the field of flow measurement technology. Background Technology

[0002] In the pilot test blocks of the Jilin Oilfield region in my country's oilfield industry, such as Hei 59, Hei 79 South, and Hei 125, the initial verification of CO2 flooding effects required precise measurement of the mass flow rate of CO2 injected into each well. The flow meters used in the field were volumetric flow meters, calculating the mass flow rate by measuring the volumetric flow rate and corresponding density. However, the CO2 medium being measured experiences significant temperature and pressure variations during injection, meaning its density is a variable. The flow meters were calibrated using water as the calibration medium, and water is an incompressible fluid with a relatively constant density under different ambient temperatures and pressures. Furthermore, the viscosity, density, and other physical properties of water differ considerably from those of CO2 measured in production. Therefore, using water-calibrated flow meters to measure CO2 flow rate introduces a certain error. This means that flow meters calibrated with water cannot meet the production requirements for measuring the mass flow rate of multivariable media, and the magnitude of the error is uncertain, ultimately affecting the evaluation of CO2 flooding effectiveness. Summary of the Invention

[0003] To address the aforementioned problems in the existing technology, this application provides a flow meter calibration device and calibration method. The device uses a PLC system to interlock and control each component, calculates relevant parameters such as the mass and density of gases and liquids, and generates a library of flow curves for different flow meters measuring different media, thereby meeting the calibration requirements of flow metering instruments under different temperatures, pressures, and volumetric flow rates.

[0004] To achieve the above objectives, the technical solution of this application is a flow meter calibration device, comprising:

[0005] Media storage tank, used for storing media;

[0006] The first heating and cooling unit is used to ensure the gas phase balance of the medium storage tank. It cools the tank when the pressure is too high and heats it to vaporize when the pressure is too low.

[0007] Booster pumps are used to increase the pressure of media within pipelines;

[0008] Pressure stabilizing tanks are used to maintain the pressure of media inside pipelines;

[0009] A constant-volume water tank is a container used to provide a medium of constant volume.

[0010] Air conditioning is used to maintain a constant temperature of the medium in a constant-volume water tank under standard atmospheric pressure.

[0011] Metering pumps are used to transport, measure, and regulate the flow rate and velocity of media.

[0012] A sampler is used to measure the mass of a medium.

[0013] The second heating and cooling unit is used to heat or cool the medium in the pipeline to keep the medium at a constant temperature.

[0014] A vacuum pump is used to evacuate the air from the pipeline to ensure a vacuum in the system and prevent residual gas in the pipeline from affecting the measurement results during measurement.

[0015] A flow meter is used to measure the medium flowing through it;

[0016] Orifice plates are used to create a pressure differential in pipelines to ensure that the medium enters the sampler;

[0017] PLC controllers are used to achieve automated control and data storage.

[0018] Furthermore, the calibration device also includes a hot air drying device, which is used to purge the pipeline with hot air after the metering pump has been calibrated with water, so as to avoid water containing impurities from affecting the accuracy of the calibration.

[0019] Furthermore, the calibration device also includes a pressure sensor, a temperature sensor, and a filter. The filter is used to filter impurities in the medium inside the pipeline. The pressure sensor is used to detect the pressure of the medium inside the pipeline and transmit a signal. The temperature sensor is used to detect the temperature of the medium inside the pipeline and transmit a signal. The PLC controller is electrically connected to the pressure sensor and the temperature sensor. The PLC controller receives the pressure and temperature signals, compares them with the set values, and controls the control valves of the chiller / heater unit, booster pump, and pressure tank to stabilize the system parameters.

[0020] Furthermore, the first heating and cooling unit is connected to the medium storage tank, the output end of the medium storage tank is connected to the booster pump, and the other end of the booster pump is connected to the pressure stabilizing tank, the metering pump, and the second heating and cooling unit respectively.

[0021] The first branch of the constant volume water tank is connected to the air conditioner, and the second branch of the constant volume water tank is connected to the metering pump. The output end of the metering pump is connected to the sampler and the orifice plate, respectively. The second heating and cooling unit is connected to the flow meter and the vacuum pump, respectively. The other end of the pressure stabilizing tank is also connected to the input end of the medium storage tank. A gas phase control valve is installed on the pipeline of the input end of the medium storage tank. A pressure stabilizing tank control valve is installed between the gas phase control valve and the pressure stabilizing tank. The PLC controller is electrically connected to the first heating and cooling unit, the booster pump, the air conditioner, the metering pump, the pressure stabilizing tank control valve, and the second heating and cooling unit, respectively.

[0022] Furthermore, a filter is provided between the second heating and cooling unit and the flow meter and vacuum pump, and the filter is connected to the flow meter and vacuum pump respectively.

[0023] Furthermore, the booster pump input end is equipped with a booster pump control valve, and the booster pump output end is equipped with a check valve; a control valve and a metering pump control valve are sequentially installed between the check valve and the metering pump; a metering pump check valve is also installed at the metering pump output end; a constant volume water tank electric valve is also installed on the connection pipeline between the control valve and the constant volume water tank; a flat gate valve is also installed between the metering pump check valve and the external pipeline; an electric valve is also installed between the check valve and the chiller / heater unit; and a sampler input control valve is also installed between the metering pump check valve and the sampler; the PLC controller is electrically connected to the constant volume water tank electric valve and the electric valve respectively.

[0024] The sampler input control valve is designed to prevent water from entering the sampler during the calibration of the metering pump.

[0025] Furthermore, the hot air drying device is installed between the constant volume water tank and the metering pump, and an output control valve is also installed on the output pipeline of the hot air drying device.

[0026] Furthermore, cryogenic flat gate valve A and cryogenic flat gate valve B are respectively installed at both ends of the flow meter; pressure sensor and temperature sensor are installed between the orifice plate and cryogenic flat gate valve A; sampler control valve A and sampler control valve B are respectively installed at both ends of the sampler, and a vent valve is installed at the output end of the vacuum pump.

[0027] Furthermore, a gas-phase cryogenic flat gate valve is also installed between the gas phase control valve and the sampler input control valve.

[0028] The calibration method of the present invention comprises the following specific steps:

[0029] Step 1: Open the electric valve and flat gate valve of the constant volume water tank, start the air conditioner and metering pump, and water at standard atmospheric pressure and 20°C will be transported from the constant volume water tank to the metering pump. The water flowing through the metering pump will be transported to the designated location. The standard volumetric displacement of the metering pump will be calibrated by calculating the number of revolutions of the metering pump.

[0030] Step 2: After the metering pump is calibrated, open the output control valve and the hot air drying device to dry the medium in the pipeline.

[0031] Step 3: Close the output control valve, the electric valve of the constant volume water tank, the gas phase control valve, the booster pump control valve and the flat gate valve, and open the other valves. Use the PLC to automatically control the vacuum pump to extract air from the pipeline to avoid too many impurities that could lead to the formation of a two-phase region, resulting in phenomena such as slug flow, bubbly flow, and half-pipe flow.

[0032] Step 4: Then, turn on the booster pump, pressure stabilizing tank, and second heating / cooling unit to fill the device with liquid test medium for closed-loop pre-cooling. Return the gaseous medium to the medium storage tank through the gas phase cryogenic flat gate valve and gas phase control valve. After the system cools down, close the gas phase cryogenic flat gate valve. By continuously adjusting the second heating / cooling unit and booster pump, the pressure inside the device will continuously change as the temperature rises or falls. The signal transmitted by the pressure sensor is fed back to the PLC controller, which automatically controls the pressure. When pressure replenishment is needed, the booster pump is used to increase the pressure; when pressure relief is needed, the pressure stabilizing tank control valve is used to relieve pressure, ensuring that the system pressure and temperature reach the target set values.

[0033] Step 5: After the temperature and pressure stabilize, the mass is measured by tare and weighing using a sampler, and the corresponding density is calculated. At the same time, the medium circulation volume per unit time is measured by a metering pump to determine the volumetric flow rate. The mass flow rate is calculated according to the formula and compared with the actual value of the flow meter being tested to determine the accuracy of the flow meter.

[0034] The present invention, employing the above technical solution, achieves the following technical effects: The PLC controller performs detection, alarm, analysis, and interlock control on the device, and receives data such as temperature, pressure, and liquid level. It uses a sampler for weighing and measurement, calibrating the density of the tested medium under different temperatures and pressures. Simultaneously, it measures the CO2 circulation volume per unit time using a metering pump to obtain the volumetric flow rate, thereby correcting the mass flow rate of the measured flowmeter. At the same time, all data is uploaded to the PLC controller database in real time to establish isochoric and isodense curves, providing a basis for subsequent calibration of similar flowmeters. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the present invention.

[0036] Explanation of the numbers in the diagram: 1. Medium storage tank; 2. First heating / cooling unit; 3. Pressure stabilizing tank; 4. Booster pump; 5. Constant volume water tank; 6. Metering pump; 7. Pressure stabilizing tank control valve; 10. Second heating / cooling unit; 11. Filter; 12. Sampler; 13. Vacuum pump; 14. Orifice plate; 15. Air conditioner; 16. Hot air drying device; 17. Flow meter; 19. Gas phase control valve; 20. Output control valve; 21. Constant volume water tank electric valve; 22. Metering pump control valve. 25. Flat gate valve; 26. Electric valve; 31. Booster pump control valve; 36. Vent valve; 40. Cryogenic flat gate valve A; 41. Cryogenic flat gate valve B; 44. Sampler control valve A; 45. Sampler control valve B; 47. Gas phase cryogenic flat gate valve; 49. Control valve; 53. Sampler input control valve; 60. PLC controller; 65. Temperature sensor; 66. Pressure sensor; 71. Check valve; 73. Metering pump check valve. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments: the present application will be further described and illustrated using these examples. Example

[0038] In this embodiment, the medium in the medium storage tank 1 is CO2.

[0039] like Figure 1 As shown, this embodiment provides a flow meter calibration device, including a medium storage tank 1, for storing CO2 and providing a medium for calibrating the entire device;

[0040] The first heating and cooling unit 2 is used to ensure the gas phase balance of the medium storage tank 1. It cools when the pressure inside the tank is too high and heats and vaporizes when the pressure is too low.

[0041] Pressure stabilizing tank 3 is used to maintain the pressure of the medium inside the pipeline;

[0042] Booster pump 4 is used to increase the pressure of the medium inside the pipeline;

[0043] Constant volume water tank 5 is a container used to provide a medium with a constant volume.

[0044] Metering pump 6 is used for conveying, metering, and regulating the flow rate and velocity of the medium.

[0045] The second heating and cooling unit 10 is used to heat or cool the medium in the pipeline to keep the medium at a constant temperature.

[0046] Sampler 12 is used to measure the mass of the medium;

[0047] Vacuum pump 13 is used to evacuate the air in the pipeline to ensure a vacuum in the system and avoid residual gas in the pipeline during measurement, which would affect the measurement results.

[0048] The orifice plate 14 is used to create a pressure differential in the pipeline to ensure that the medium enters the sampler 12;

[0049] Air conditioner 15 is used to maintain a constant temperature of the medium in constant volume water tank 5 under standard atmospheric pressure;

[0050] Flow meter 17 is used to measure the medium flowing through it;

[0051] The PLC controller 60 is used to realize automated control and data storage.

[0052] Furthermore, the calibration device also includes a hot air drying device 16, which is used to blow hot air through the pipeline after the metering pump 6 has completed the calibration of the water, so as to avoid water containing impurities from affecting the accuracy of the calibration.

[0053] Furthermore, the calibration device also includes a pressure sensor 66, a temperature sensor 65, and a filter 11. The filter 11 is used to filter impurities in the medium inside the pipeline. The PLC controller 60 is electrically connected to the pressure sensor 66 and the temperature sensor 65. The pressure sensor 66 is used to detect the pressure of the medium inside the pipeline and transmit a signal, and the temperature sensor 65 is used to detect the temperature of the medium inside the pipeline and transmit a signal.

[0054] The PLC controller 60 receives pressure and temperature signals, compares them with set values, and controls the second heating / cooling unit 10, booster pump 4, and pressure stabilizing tank control valve 7 to stabilize system parameters.

[0055] Furthermore, the first heating and cooling unit 2 is connected to the medium storage tank 1, the output end of the medium storage tank 1 is connected to the booster pump 4, and the other end of the booster pump 4 is connected to the pressure stabilizing tank 3, the metering pump 6, and the second heating and cooling unit 10 respectively.

[0056] The first branch of the constant volume water tank 5 is connected to the air conditioner 15, and the second branch of the constant volume water tank 5 is connected to the metering pump 6. The output end of the metering pump 6 is connected to the sampler 12 and the orifice plate 14 respectively. The second heating and cooling unit 10 is connected to the flow meter 17 and the vacuum pump 13 respectively. The other end of the pressure stabilizing tank 3 is also connected to the input end of the medium storage tank 1. A gas phase control valve 19 is installed on the pipeline of the input end of the medium storage tank 1. A pressure stabilizing tank control valve 7 is installed between the gas phase control valve 19 and the pressure stabilizing tank 3. The PLC controller 60 is electrically connected to the first heating and cooling unit 2, the booster pump 4, the air conditioner 15, the metering pump 6, the pressure stabilizing tank control valve 7, and the second heating and cooling unit 10 respectively.

[0057] Furthermore, a filter 11 is provided between the second heating and cooling unit 10 and the flow meter 17 and vacuum pump 13, and the filter 11 is connected to the flow meter 17 and vacuum pump 13 respectively.

[0058] Furthermore, the booster pump 4 is equipped with a booster pump control valve 31 at its input end and a check valve 71 at its output end. A control valve 49 and a metering pump control valve 22 are sequentially installed between the check valve 71 and the metering pump 6. A metering pump check valve 73 is also installed at the output end of the metering pump 6. A volumetric water tank electric valve 21 is installed on the pipeline connecting the control valve 49 and the volumetric water tank 5. A flat gate valve 25 is installed between the metering pump check valve 73 and the external pipeline. An electric valve 26 is installed between the check valve 71 and the second cooling and heating unit 10. A sampler input control valve 53 is installed between the metering pump check valve 73 and the sampler 12. The PLC controller 60 is electrically connected to the volumetric water tank electric valve 21 and the electric valve 26, respectively.

[0059] The sampler input control valve 53 is used to prevent water from entering the sampler 12 when calibrating the metering pump 6.

[0060] Furthermore, the hot air drying device 16 is installed between the constant volume water tank 5 and the metering pump 6, and an output control valve 20 is also installed on the output pipe of the hot air drying device 16.

[0061] Furthermore, a cryogenic flat gate valve A40 and a cryogenic flat gate valve B41 are respectively installed at both ends of the flow meter 17; a pressure sensor 66 and a temperature sensor 65 are installed between the orifice plate 14 and the cryogenic flat gate valve A40; a sampler control valve A44 and a sampler control valve B45 are respectively installed at both ends of the sampler 12; and a vent valve 36 is installed at the output end of the vacuum pump 13.

[0062] Furthermore, a gas phase cryogenic flat gate valve 47 is also installed between the gas phase control valve 19 and the sampler input control valve 53.

[0063] The calibration method of the present invention comprises the following specific steps:

[0064] Step 1: Open the electric valve 21 and the flat gate valve 25 of the constant volume water tank, start the air conditioner 15 and the metering pump 6, and transport water at standard atmospheric pressure and 20°C from the constant volume water tank 5 to the metering pump 6. The water flowing through the metering pump 6 is transported to the designated location; the standard volume displacement of the metering pump 6 is calibrated by calculating the rotation speed of the metering pump 6.

[0065] Step 2: After the metering pump 6 is calibrated, open the output control valve 20 and the hot air drying device 16 to dry the medium in the pipeline.

[0066] Step 3: Close the output control valve 20, the constant volume water tank electric valve 21, the gas phase control valve 19, the booster pump control valve 31, and the flat gate valve 25. Open the other valves and use the PLC to automatically control the vacuum pump 13 to extract air from the pipeline to avoid too many impurities that could lead to the formation of a two-phase region, resulting in slug flow, bubbly flow, or half-pipe flow.

[0067] Step 4: Then, turn on the booster pump 4, the pressure stabilizing tank 3, and the second heating and cooling unit 10 to fill the device with liquid CO2, the test medium, for closed-loop precooling. The vaporized CO2 is then returned to the medium storage tank 1 through the gas phase cryogenic flat gate valve 47 and the gas phase control valve 19. After the system cools down, the gas phase cryogenic flat gate valve 47 is closed. By continuously adjusting the second heating and cooling unit 10 and the booster pump 4, the pressure inside the device will continuously change as the temperature rises or falls. The signal transmitted by the pressure sensor 66 is fed back to the PLC controller 60. The PLC controller 60 automatically controls the pressure. When pressure replenishment is needed, the booster pump 4 is used to increase the pressure; when pressure relief is needed, the pressure stabilizing tank control valve 7 is used to relieve pressure, so that the pressure and temperature inside the system reach the target set values.

[0068] Step 5: After the temperature and pressure stabilize, the mass is measured by tare weighing using sampler 12, and the corresponding density is calculated; at the same time, the CO2 circulation volume per unit time is measured by metering pump 6, the volumetric flow rate is measured, the mass flow rate is calculated according to the formula, and the result is compared with the actual value of the flow meter 17 to determine the accuracy of the flow meter 17.

[0069] When it is necessary to calibrate different mass flow meters 17, close the cryogenic flat gate valve A40 and cryogenic flat gate valve B41, replace other flow meters 17, and repeat the above steps 2-5 to calibrate the mass flow of other measured flow meters 17.

[0070] In addition, to facilitate the simplified calibration of similar flow meters 17 in the later stages, the temperature is changed by the second heating and cooling unit 10 or the pressure is changed by the booster pump 4. The medium data under different pressures and temperatures is measured, the sampler 12 is used for weighing, and the CO2 circulation volume per unit time is measured by the metering pump 6 to obtain the volumetric flow rate. The mass flow rate is calculated according to the formula. During the process, all data is uploaded to the PLC controller 60 database in real time to establish the isochoric curve, which provides a basis for the calibration of similar flow meters 17 in the later stages. It is not necessary to repeat the calibration of similar flow meters 17. It is only necessary to find the isochoric curve. When the pressure is constant, the temperature is changed by the second heating and cooling unit 10. For every 5° or other degree increase, the real-time phase state of CO2 is measured and parameters such as density and mass flow rate are recorded. Similarly, when the temperature is constant, the pressure is changed by the booster pump 4, and the real-time phase state of CO2 is measured and parameters such as density and mass flow rate are recorded. The medium data at different pressures and temperatures are measured, and the sampler 12 is used for weighing. The CO2 circulation volume per unit time is measured by the metering pump 6 to measure the volumetric flow rate. The mass flow rate is calculated according to the formula, providing a basis for the subsequent calibration of the same type of flow meter 17.

[0071] It should be noted that the media in the media storage tank of this invention includes, but is not limited to, carbon dioxide, nitrogen, and oxygen.

[0072] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A flow meter calibration device, characterized in that, include A media storage tank (1) is used for storing media and providing media for the calibration of the entire device; The first heating and cooling unit (2) is used to ensure the gas phase balance of the medium storage tank (1). When the pressure inside the tank is too high, it is cooled; when the pressure is too low, it is heated and vaporized. Pressure stabilizing tank (3) is used to maintain the pressure of the medium in the pipeline; Booster pump (4) is used to increase the pressure of the medium in the pipeline; A constant-volume water tank (5) is a container used to provide a medium with a constant volume. Metering pump (6) is used to transport, measure and regulate the flow rate and velocity of the medium; The second heating and cooling unit (10) is used to heat or cool the medium in the pipeline to keep the medium at a constant temperature. Sampler (12) is used to measure the mass of the medium; Vacuum pump (13) is used to evacuate the pipe to ensure the vacuum in the system and avoid residual gas in the pipe during measurement, which would affect the measurement results. An orifice plate (14) is used to create a pressure differential in the pipeline to ensure that the medium enters the sampler (12); Air conditioning (15) is used to ensure that the temperature of the medium in the constant volume water tank (5) is constant under standard atmospheric pressure; A flow meter (17) is used to measure the medium flowing through it; The PLC controller (60) is used to realize automated control and data storage; the first heating and cooling unit (2) is connected to the medium storage tank (1), the output end of the medium storage tank (1) is connected to the booster pump (4), and the other end of the booster pump (4) is connected to the pressure stabilizing tank (3), the metering pump (6), and the second heating and cooling unit (10) respectively. The first branch of the constant volume water tank (5) is connected to the air conditioner (15), and the second branch of the constant volume water tank (5) is connected to the metering pump (6); the output end of the metering pump (6) is connected to the sampler (12) and the orifice plate (14) respectively; the second heating and cooling unit (10) is connected to the flow meter (17) and the vacuum pump (13) respectively; the other end of the pressure stabilizing tank (3) is also connected to the input end of the medium storage tank (1); a gas phase control valve (19) is installed on the pipeline of the input end of the medium storage tank (1); a pressure stabilizing tank control valve (7) is installed between the gas phase control valve (19) and the pressure stabilizing tank (3); the PLC controller (60) is electrically connected to the first heating and cooling unit (2), the booster pump (4), the air conditioner (15), the metering pump (6), the pressure stabilizing tank control valve (7), and the second heating and cooling unit (10) respectively; Pressure sensor (66) is used to detect the pressure of the medium in the pipeline and transmit the signal; Temperature sensor (65) is used to detect the temperature of the medium in the pipeline and transmit the signal.

2. The flow meter calibration device according to claim 1, characterized in that, Also includes Hot air drying device (16) is used to purge the pipeline with hot air after the metering pump (6) has calibrated the water. Filter (11) is used to filter impurities in the medium inside the pipeline; The hot air drying device (16) is installed between the constant volume water tank (5) and the metering pump (6). An output control valve (20) is also installed on the output pipeline of the hot air drying device (16). The filter (11) is connected to the flow meter (17) and the vacuum pump (13) respectively. The PLC controller (60) is electrically connected to the pressure sensor (66) and the temperature sensor (65).

3. The flow meter calibration device according to claim 2, characterized in that, The booster pump (4) is also equipped with a booster pump control valve (31) at the input end and a check valve (71) at the output end. A control valve (49) and a metering pump control valve (22) are installed between the check valve (71) and the metering pump (6) in sequence. A metering pump check valve (73) is installed at the output end of the metering pump (6). A metering tank electric valve (21) is installed on the connection pipeline between the control valve (49) and the constant volume water tank (5). A flat gate valve (25) is installed between the metering pump check valve (73) and the external pipeline. An electric valve (26) is installed between the check valve (71) and the second cooling and heating unit (10). A sampler input control valve (53) is installed between the metering pump check valve (73) and the sampler (12). The PLC controller (60) is electrically connected to the constant volume water tank electric valve (21) and the electric valve (26) respectively. The flow meter (17) is equipped with a low-temperature flat gate valve A (40) and a low-temperature flat gate valve B (41) at its two ends.

4. The flow meter calibration device according to claim 3, characterized in that, The sampler (12) is equipped with sampler control valve A (44) and sampler control valve B (45) at both ends, and a vent valve (36) is installed at the output end of the vacuum pump (13).

5. A flowmeter calibration device according to claim 3, characterized in that, The pressure sensor (66) and temperature sensor (65) are installed between the orifice plate (14) and the cryogenic flat gate valve A (40).

6. A flowmeter calibration device according to claim 3, characterized in that, A gas phase cryogenic flat gate valve (47) is also installed between the gas phase control valve (19) and the sampler input control valve (53).

7. A method for calibration using the flowmeter calibration device as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Open the electric valve (21) and the flat gate valve (25) of the constant volume water tank, start the air conditioner (15) and the metering pump (6), and deliver water at standard atmospheric pressure and 20°C from the constant volume water tank (5) to the metering pump (6). The water flowing through the metering pump (6) is delivered to the designated location. The standard volume displacement of the metering pump (6) is calibrated by calculating the rotation speed of the metering pump (6). Step 2: After the metering pump (6) is calibrated, open the output control valve (20) and the hot air drying device (16) to dry the medium in the pipeline; Step 3: Close the output control valve (20), the constant volume water tank electric valve (21), the gas phase control valve (19), the booster pump control valve (31) and the flat gate valve (25), open the other valves, and automatically control the vacuum pump (13) through the PLC to extract air from the pipeline; Step 4: Then turn on the booster pump (4), pressure stabilizing tank (3), and second heating and cooling unit (10) to fill the device with liquid test medium for closed-loop pre-cooling. The vaporized medium is returned to the medium storage tank (1) through the gas phase low temperature flat gate valve (47) and gas phase control valve (19). After the system cools down, the gas phase low temperature flat gate valve (47) is closed. By continuously adjusting the second heating and cooling unit (10) and booster pump (4), the pressure in the device will change continuously as the temperature rises or falls. The signal transmitted by the pressure sensor (66) is fed back to the PLC controller (60). The PLC controller (60) automatically controls the pressure. When pressure needs to be replenished, the booster pump (4) is used to increase the pressure; when pressure needs to be released, the pressure stabilizing tank control valve (7) is used to release the pressure, so that the pressure and temperature in the system reach the target set value. Step 5: After the temperature and pressure stabilize, the mass is measured by tare and weighing using the sampler (12), and the corresponding density is calculated. At the same time, the medium circulation volume per unit time is measured by the metering pump (6), the volumetric flow rate is measured, the mass flow rate is calculated according to the formula, and the actual value is compared with that of the flow meter (17) being tested to determine the accuracy of the flow meter (17).

8. The calibration method according to claim 7, characterized in that, When it is necessary to calibrate different mass flow meters (17), close the low temperature flat gate valve A (40) and the low temperature flat gate valve B (41), replace other flow meters (17), and repeat the above steps 2-5 to calibrate the mass flow of other measured flow meters (17).

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