Gas Positive Pressure Dual Standard Comparison Device

Abstract

This invention relates to the field of gas flow detection and calibration technology, and more specifically, to a gas positive pressure dual-standard gauge comparison device, comprising: a closed loop having a standard pass and a test pass; a gas supply system for supplying gas flow into the loop, causing the gas flow to circulate within the loop; a standard gauge module connected in series with the standard pass for collecting the standard gas flow rate value passing through the standard pass; and a test gauge module connected in series with the test pass for calibrating the test gauge module by measuring the gas flow rate passing through the test pass; wherein the standard pass includes two standard gauges of the same specification, which are connected in series with the standard pass and simultaneously collect flow rate data for mutual comparison and verification to calibrate the test gauge module.

Description

Technical Field

[0001] This invention relates to the field of gas flow detection and calibration technology, and more specifically, to a gas positive pressure dual standard meter comparison device. Background Technology

[0002] With the widespread application of clean energy sources such as natural gas and industrial gases in commercial and industrial production and urban gas supply, gas flow meters, as core equipment for trade measurement and process control, directly affect the fairness of interests for both supply and demand sides, as well as the safety and stability of industrial production. Currently, mainstream gas flow meters on the market include turbine flow meters, Roots flow meters, and ultrasonic flow meters, which are widely used in urban gas gate stations, industrial pipelines, and commercial user scenarios with pressure ≤1.2MPa.

[0003] However, most flow meter manufacturers and testing institutions in China still widely use the negative pressure method critical flow sonic nozzle standard device as the testing method for flow meters. While this type of device is simple in structure and low in cost, it suffers from many insurmountable technical defects in practical applications: Firstly, the adaptability to operating conditions is poor. The negative pressure method is used in a negative pressure environment below atmospheric pressure, and the pressure of the instrument under test is not adjustable and the gas density is fixed. This is significantly different from the positive pressure conditions (0.1MPa~1.2MPa) actually used by the flow meter. As a result, key parameters such as gas density and flow rate deviate greatly from the actual field conditions, which can easily lead to the problem of "passing inspection but exceeding the error tolerance in field use", which seriously affects the accuracy of trade measurement. Secondly, the flow regulation is rigid. A single critical flow sonic nozzle corresponds to only one fixed flow point. If it is necessary to cover the full range calibration of the instrument under test, it is necessary to frequently change nozzles of different specifications, which is cumbersome and time-consuming. At the same time, the valve switching process is prone to flow fluctuations, introducing additional measurement errors. Third, the accuracy limit is low. The flow coefficient of the nozzle is easily affected by temperature, humidity and medium impurities and drifts. Moreover, there is a lack of effective benchmark verification mechanism, which results in the measurement uncertainty of the device being ≥0.5%, making it difficult to meet the calibration requirements of high-precision flow meters (such as Class 1.0 and above).

[0004] Although positive pressure testing technology is widely used in developed countries, and it can effectively solve the core defects of negative pressure methods by simulating positive pressure conditions on site, there is still room for improvement in existing positive pressure devices: some positive pressure devices use a single standard meter as a reference, lacking redundant verification, and systematic errors such as wear and calibration drift of the standard meter itself will be directly transmitted to the meter under test, affecting the reliability of calibration results; some devices have a single channel specification, making it difficult to adapt to the testing needs of multi-diameter flow meters such as DN25~DN200; at the same time, the temperature and pressure control accuracy of existing devices is insufficient and the flow regulation response is slow, which further limits the calibration accuracy and testing efficiency.

[0005] Based on the current state of the industry, there is an urgent need for a gas positive pressure comparison device that can achieve multi-caliber adaptation, high-precision benchmark verification, and accurate simulation of operating conditions. Summary of the Invention

[0006] The main objective of this invention is to provide a gas positive pressure dual standard table comparison device to solve at least one of the technical problems mentioned in the background art.

[0007] To address the aforementioned technical problems, this invention proposes a gas positive pressure dual standard table comparison device, comprising: A closed loop with standard access points and test access points; The air supply system is used to deliver airflow into the loop, allowing the airflow to circulate within the loop; The standard meter module, connected in series with the standard through-hole, is used to collect the standard gas flow rate value passing through the standard through-hole; The test module is connected in series with the test gate, and the test module is calibrated by the air flow rate through the test gate. The standard access point includes two standard meters of the same specification. The two standard meters are connected in series on the standard access point and synchronously collect flow data for mutual comparison and verification in order to calibrate the meter module under test.

[0008] In the above technical solution, the standard channel further includes: a first standard channel, a second standard channel and a third standard channel connected in parallel, and two standard tables are provided on each of the first standard channel, the second standard channel and the third standard channel; Among them, the two standard meters on the first standard channel are both DN200 turbine flow meters; the two standard meters on the second standard channel are both DN100 Roots flow meters; and the two standard meters on the third standard channel are both DN50 Roots flow meters.

[0009] In any of the above technical solutions, further, the first standard channel is a DN200 pipe; the second standard channel is a DN100 pipe; and the third standard channel is a DN50 pipe.

[0010] In any of the above technical solutions, further, the inspection through-pass includes: a first inspection channel, a second inspection channel, a third inspection channel, a fourth inspection channel, and a fifth inspection channel connected in parallel; Among them, the first inspection channel is a pipe with a diameter of DN200; the second inspection channel is a pipe with a diameter of DN150; the third inspection channel is a pipe with a diameter of DN100; the fourth inspection channel is a pipe with a diameter of DN80; the fifth inspection channel is a pipe with a diameter of DN50 and can be replaced with DN40, DN32, or DN25; Among them, the inspected meter module can be set on the first inspection channel, the second inspection channel, the third inspection channel, the fourth inspection channel, or the fifth inspection channel.

[0011] In any of the above technical solutions, further, the air supply system includes: an air compressor; a cold dryer connected to the air compressor, and a pressure stabilizing tank connected to the cold dryer; Among them, the pressure stabilizing tank transports the stabilized air flow into the loop.

[0012] In any of the above technical solutions, further, it further includes: a cooling system for adjusting the temperature of the air flow entering the loop from Ta to T, where Ta < T, so as to keep the air flow temperature in the loop constant.

[0013] In any of the above technical solutions, further, the cooling system includes: a heat exchanger and a coolant delivery system for continuously delivering coolant into the heat exchanger; Among them, the heat exchanger includes: An outer cylinder, with a tube-side inlet section and a tube-side outlet section respectively provided at both ends. An air supplement port leading to the inside of the tube-side inlet section is also provided on the outer wall of the outer cylinder. Liquid inlet and outlet ports are also provided on the outer wall of the outer cylinder near both ends, and both the liquid inlet and outlet ports are connected to the inner cavity of the outer cylinder; Mounting plates, there are two of them, and they are respectively arranged inside the tube-side inlet section and the tube-side outlet section to seal the inner cavity of the outer cylinder; And heat exchange tubes, which are horizontally arranged inside the outer cylinder, and both ends of the heat exchange tubes penetrate through the two mounting plates respectively; there are several heat exchange tubes, and they are spaced apart and distributed inside the outer cylinder. The gaps between the heat exchange tubes form a coolant chamber for the coolant to flow through; Among them, the outer cylinder is connected in series to the loop. One end of the tube-side inlet section forms a circulation inlet for the air flow circulation in the loop, and one end of the tube-side outlet section forms a circulation outlet for the air flow circulation in the loop; an air flow mixing chamber connected to the air supplement port and the circulation inlet is formed inside the tube-side inlet section, and the air flow generated by the air supply system leads to the air supplement port; Among them, the air flow entering from the air supplement port and the air flow entering from the circulation inlet enter the air flow mixing chamber to be mixed and then are discharged from the other end of the tube-side inlet section and enter the heat exchange tubes, and finally are discharged from the circulation outlet.

[0014] In any of the above technical solutions, the pipe inlet section further includes: a first straight pipe section, an enlarged diameter section, and a second straight pipe section connected in sequence; the diameter of the second straight pipe section is larger than the diameter of the first straight pipe section. The inlet section of the tube also includes an annular sleeve fitted on the outer surface of the expansion section. The air inlet is set on the annular sleeve. An air inlet chamber is formed between the inner wall of the annular sleeve and the outer wall of the expansion section. Several through-holes are also opened on the outer wall of the expansion section. The inner cavity of the expansion section forms an airflow mixing chamber.

[0015] In any of the above technical solutions, the cooling system further includes: a temperature sensor and an electromagnetic regulating valve; The temperature sensor collects the airflow temperature in the inlet and outlet sections of the tube in real time and feeds it back to the coolant delivery system. The coolant delivery system controls the amount of coolant entering the heat exchanger by adjusting the opening of the electromagnetic regulating valve according to the received temperature signal, so as to maintain the airflow temperature in the loop at T.

[0016] In any of the above technical solutions, it further includes: a measurement and control system, which includes a pressure sensor, a humidity sensor, a data acquisition unit, and a PC control module; The pressure sensor is used to collect the real-time pressure of the standard and test gauges; the humidity sensor is used to collect the relative humidity of the airflow in the loop; the data acquisition unit transmits data in real time to the standard gauge module, the test gauge module, and various sensors via the CAN bus; the PC control module has built-in data processing software to automatically complete the comparison of the dual standard gauges and the test gauge module, temperature and pressure correction, error calculation, result judgment, and report generation.

[0017] Beneficial effects: Compared with existing technologies, This application employs a dual-standard table series comparison design, and verifies the validity of the benchmark by calculating the relative deviation (Δ≤0.1%), thus offsetting the systematic errors of a single standard table (such as wear and calibration drift). The cooling system ensures that the airflow temperature is stable and controllable within the range of 10℃ to 60℃, with fluctuations of ≤±0.5℃. It is completely consistent with the actual positive pressure conditions of natural gas gate stations and industrial pipelines, avoiding the defect of "passing inspection but exceeding tolerance on site" in the negative pressure method. The calibration results directly reflect the accuracy of the flow meter in the field.

[0018] The test port includes 5 parallel channels (DN50~DN200), and the fifth test channel is compatible with small diameter flow meters (DN15~DN40) via a tube-type structure, covering most commonly used specifications; the three channels of the standard port are adapted to 1m... 3 / h~2500m 3 With a wide flow range of / h, it can calibrate various types of flow meters such as turbine, Roots, and ultrasonic, solving the problem of "single channel and poor adaptability" of existing devices. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the connection structure of the present invention; Figure 2 This is a schematic diagram of the heat exchanger of the present invention; Figure 3 This is a schematic diagram of the internal structure of the heat exchanger of the present invention; Figure 4 This is a schematic diagram of the heat exchange tube structure of the heat exchanger of the present invention; Figure 5 yes Figure 3 Enlarged view of point A in the middle; Figure 6 This is a control block diagram of the present invention.

[0021] The annotations in the attached figures are explained as follows: 1. Loop; 2. Standard access point; 21. First standard channel; 22. Second standard channel; 23. Third standard channel; 3. Inspection access point; 31. First inspection channel; 32. Second inspection channel; 33. Third inspection channel; 34. Fourth inspection channel; 35. Fifth inspection channel; 4. Air supply system; 41. Air compressor; 42. Refrigerated dryer; 43. Pressure stabilizing tank; 5. Standard gauge module; 6. Gauge under test module; 71. Heat exchanger; 711. Outer cylinder; 7111. Tube-side inlet section; 71111. First straight pipe Section; 71112, Expanded Diameter Section; 71113, Second Straight Pipe Section; 71114, Annular Sleeve; 71115, Vent; 7112, Pipe-side Outlet Section; 7113, Air Inlet; 7114, Liquid Inlet; 7115, Liquid Outlet; 7116, Airflow Mixing Chamber; 712, Mounting Plate; 713, Heat Exchanger Tube; 72, Coolant Delivery System; 8, Temperature Sensor; 9, Electromagnetic Regulating Valve; 201, Pressure Sensor; 202, Humidity Sensor; 203, Data Acquisition Unit; 204, PC Control Module. Detailed Implementation

[0022] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of this application, and not all of the embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0023] It should be noted that, as shown in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements.

[0024] If the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0025] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] The following examples and experiments will provide a detailed description of the gas positive pressure dual standard table comparison device of this application.

[0028] Example 1: like Figures 1-6 As shown in the figure, this embodiment proposes a gas positive pressure dual standard meter comparison device, including: a closed loop 1, a standard passage 2, a test passage 3, a gas supply system 4, a standard meter module 5, and a meter under test module 6, to realize high-precision calibration of multi-diameter flow meters under positive pressure conditions.

[0029] The system consists of a closed loop 1, a gas supply system 4, a standard meter module 5, and a meter under test module 6. The loop 1 is equipped with a standard access point 2 and a test access point 3. The standard meter module 5 is connected in series with the standard access point 2, and the meter under test module 6 is connected in series with the test access point 3. Two standard meters of the same specification are connected in series with the standard access point 2 to synchronously collect flow data and compare and verify each other.

[0030] By employing a dual-standard meter series comparison design, the shortcomings of traditional single-standard meter verification without redundancy are overcome. The flow data of two standard meters of the same specification can be mutually verified, and the relative deviation is calculated to determine the validity of the benchmark. This effectively offsets the systematic errors caused by wear and calibration drift of the single standard meter itself, minimizing the influence of standard meter errors and significantly improving the accuracy and reliability of the calibration results of the meter under test. In addition, the closed loop realizes the circulation of airflow, simulating the positive pressure circulation conditions actually used by the flow meter. Compared with the negative pressure calibration method, this fundamentally solves the problem of poor adaptability to operating conditions, enabling the calibration results to directly reflect the accuracy of the flow meter in the field.

[0031] Specifically, loop 1 is a closed pipe made of 304 stainless steel. The standard access point 2 and the inspection access point 3 on loop 1 are arranged in series to ensure that the airflow passes through the standard meter module 5 and the meter under test module 6 in sequence, and the flow consistency error can be ≤±0.1%.

[0032] Standard access point 2 includes a first standard channel 21, a second standard channel 22, and a third standard channel 23 connected in parallel. These three channels are connected to the main circuit of loop 1 via a solenoid three-way valve and can automatically switch according to the range of the meter module 6 under test. Wherein: The first standard channel 21 is a DN200 pipe, equipped with two DN200 turbine flow meters (standard meter module 5), with an accuracy class of 0.2 and an applicable flow range of 125m³ / h. 3 / h~2500m 3 / h; The second standard channel 22 is a DN100 pipe, equipped with two DN100 Roots flow meters (standard meter module 5), with parameters identical to the first standard channel 21, and an applicable flow range of 3m³ / h. 3 / h~400m 3 / h; The third standard channel 23 is a DN50 pipe, equipped with two DN50 Roots flow meters (standard meter module 5), with an accuracy class of 0.2 and an applicable flow range of 1m³. 3 / h~40m 3 / h.

[0033] The standard channel 2 is configured with three parallel channels of different specifications, and each channel is adapted to different types and diameters of standard meters. This allows the standard channel 2 to cover a wide range of flow rates and adapt to the calibration requirements of meters under test with different ranges, solving the problem of traditional devices having a single standard channel and a narrow flow coverage. In addition, different channels are equipped with turbine and Roots type standard meters, which can adapt to the calibration requirements of different types of meters under test, improving the device's calibration adaptability to different types of flow meters.

[0034] Inspection channel 3 includes five parallel inspection channels: a first inspection channel 31, a second inspection channel 32, a third inspection channel 33, a fourth inspection channel 34, and a fifth inspection channel 35. Each channel is equipped with an independent flange interface and a sealing gasket. Among them: The first inspection channel 31 (DN200), the second inspection channel 32 (DN150), the third inspection channel 33 (DN100), and the fourth inspection channel 34 (DN80) are directly adapted to the corresponding diameter inspection form module 6; The fifth inspection channel 35 (DN50) adopts a tube-type structure and can be equipped with tubes of three specifications: DN25, DN32, and DN40. It achieves airtight connection through sealing gaskets and is compatible with small-diameter flow meter calibration.

[0035] For all inspection channels, the installation position of the inspected module 6 must have a straight pipe section of ≥10 times the pipe diameter reserved before and after it (e.g., a 2m straight pipe section reserved for the DN200 channel) to eliminate flow interference.

[0036] The inspection channel 3 features multiple parallel inspection channels, covering most commonly used flowmeter specifications from large to small diameters. This allows a single device to calibrate multiple diameter flowmeters without requiring dedicated calibration devices for different diameters, significantly reducing equipment costs for flowmeter calibration. Furthermore, the flowmeter module 6 can be flexibly switched to different inspection channels, offering convenient operation and reducing equipment adjustment time when changing flowmeters, thus improving calibration efficiency. The multi-specification design of the fifth inspection channel 35 enables the calibration of small-diameter flowmeters, further expanding the device's applicability.

[0037] The air supply system 4 consists of an air compressor 41, a refrigerated dryer 42, and a pressure stabilizing tank 43 connected in series. The parameters of the air compressor 41 are: output pressure range of 0.1MPa~1.5MPa, and exhaust volume ≥50m³. 3 / min; refrigerated dryer with a dew point temperature ≤-20℃ to ensure compressed air moisture content ≤10mg / m³ 3 The pressure stabilizing tank 43 is equipped with a self-regulating pressure regulating valve, with an output pressure fluctuation ≤ ±0.01MPa. Dry, clean compressed air is continuously supplied to the loop 1 via the air supply system 4. After being cooled to the set temperature by the cooling system, it flows sequentially to the standard gauge module 5 and the gauge under test module 6. Finally, it mixes with the airflow replenished into the loop 1 by the air supply system 4 and flows back to the cooling system, completing the cycle. During the airflow circulation within the loop, because the air supply system 4 continuously replenishes the airflow, excess gas in the loop 1 is discharged through its pre-set exhaust structure to maintain a positive pressure environment, thereby balancing the pressure.

[0038] Air compressor 41 provides a continuous airflow source for the device, ensuring positive pressure conditions within loop 1; refrigerated dryer dries the airflow, removing moisture to prevent condensation within loop 1 or corrosion and damage to the flow meter, while also preventing moisture from affecting airflow density and flow pattern, ensuring calibration accuracy; pressure stabilizing tank regulates the airflow pressure, stabilizing the airflow pressure delivered to the loop and avoiding flow measurement errors caused by pressure fluctuations, thus ensuring smooth calibration.

[0039] Example 2: This embodiment is an improvement based on Embodiment 1.

[0040] like Figure 1 As shown, in this embodiment, the comparison device further includes a cooling system, which adjusts the temperature of the airflow entering the loop 1 from the initial temperature Ta to the set temperature T and maintains it at a constant temperature.

[0041] The cooling system includes a heat exchanger 71 and a coolant delivery system 72 for continuously supplying coolant to the heat exchanger 71.

[0042] like Figures 2-4 As shown, the heat exchanger 71 includes an outer cylinder 711, a mounting plate 712, and heat exchange tubes 713. The outer cylinder 711 has a tube-side inlet section 7111 and a tube-side outlet section 7112 at both ends. The outer wall of the outer cylinder 711 has a gas inlet 7113 leading to the tube-side inlet section 7111, and also has a liquid inlet 7114 and a liquid outlet 7115 near both ends. The liquid inlet 7114 and the liquid outlet 7115 are both connected to the inner cavity of the outer cylinder 711. There are two mounting plates 712, which are respectively located in the tube-side inlet section 7111 and the tube-side outlet section 7112 to seal the inner cavity of the outer cylinder 711. The heat exchange tubes 713 are horizontally arranged in the inner cavity of the outer cylinder 711, and their two ends pass through the two mounting plates 712 respectively. There are several heat exchange tubes 713, which are distributed at intervals. The gaps between the heat exchange tubes 713 form a coolant chamber.

[0043] The outer cylinder 711 is connected in series with the ring channel. One end of the tube-side inlet section 7111 forms the circulation inlet for airflow circulation within the ring channel, and one end of the tube-side outlet section 7112 forms the circulation outlet. An airflow mixing chamber 7116 is formed in the tube-side inlet section 7111, which is connected to the air supply port 7113 and the circulation inlet. The airflow generated by the air supply system flows to the air supply port 7113. The airflow entering from the air supply port 7113 and the airflow entering from the circulation inlet are mixed in the airflow mixing chamber 7116, and then discharged from the other end of the tube-side inlet section 7111 and enter the heat exchange tube 713, and finally discharged from the circulation outlet.

[0044] The structural design of the outer cylinder 711, mounting plate 712, and heat exchange tube 713 of the heat exchanger 71 forms an independent coolant chamber and airflow channel, enabling efficient heat exchange between the coolant and the airflow. This high heat exchange efficiency allows for rapid adjustment of the airflow temperature to the set value. The design of the air inlet 7113 and the airflow mixing chamber 7116 ensures that the new airflow supplied by the air supply system is fully mixed with the circulating airflow in the loop before entering the heat exchange tube 713. This guarantees uniform temperature and pressure of the mixed airflow and avoids local flow and temperature fluctuations caused by uneven airflow mixing. The mixed airflow is then subjected to constant temperature treatment through the heat exchange tube 713, which makes the temperature of the airflow entering the loop more uniform and stable, improving the temperature control accuracy of the entire loop.

[0045] like Figure 3 , Figure 5 As shown, in this embodiment, the optimized pipe inlet section 7111 includes a first straight pipe section 71111, an expansion section 71112, and a second straight pipe section 71113 connected in sequence. The diameter of the second straight pipe section 71113 is larger than the diameter of the first straight pipe section 71111. The pipe inlet section 7111 also includes an annular sleeve 71114 sleeved on the outer surface of the expansion section 71112. The air inlet 7113 is disposed on the annular sleeve 71114. An air inlet chamber is formed between the inner wall of the annular sleeve 71114 and the outer wall of the expansion section 71112. Several through-holes 71115 are opened on the outer wall of the expansion section 71112. An airflow mixing chamber 7116 is formed in the inner cavity of the expansion section 71112.

[0046] The expansion section 71112 of the inlet section 7111 provides sufficient space for airflow mixing, allowing the new airflow to fully mix with the circulating airflow. The annular sleeve 71114 and the air supply chamber ensure that the new airflow from the air supply system enters the expansion section 71112 evenly through multiple air holes 71115, avoiding airflow impact caused by single-point air supply and ensuring the uniformity of airflow mixing. In addition, the gradual diameter design of the first straight pipe section 71111 and the second straight pipe section 71113 allows for a smooth transition of airflow velocity within the inlet section 7111, reducing disturbances caused by abrupt changes in flow pattern and further improving the stability of the airflow pattern.

[0047] It should be noted that the taper of the expansion section 71112 is 10°-30°. This taper range allows the airflow to contract smoothly within the airflow mixing chamber 7116, avoiding sudden changes in local flow velocity caused by an excessively large taper, or poor mixing effect caused by an excessively small taper.

[0048] It should be noted that the air vent 71115 on the expanded diameter section 71112 is an inclined hole with an inclination angle of 45°-60°.

[0049] The opening direction of the inclined holes is consistent, and they are all inclined along the flow direction of the airflow. When the air flows out through the inclined holes, it can flow along the mainstream flow direction and merge into the mainstream inside the expansion section 71112, rather than rushing in vertically.

[0050] In addition, this setting can significantly reduce the airflow disturbance caused by the collision between the supplementary airflow and the circulating airflow, avoid problems such as eddies and backflow caused by vertical convergence, and enable the two airflows to merge smoothly, further improving the uniformity of the mixed airflow; at the same time, the downstream convergence method ensures the overall flow stability of the airflow and effectively reduces the turbulence of the incoming flow.

[0051] In this embodiment, the optimized cooling system further includes a temperature sensor and an electromagnetic regulating valve; wherein, the temperature sensor collects the airflow temperature in the tube inlet section 7111 and the tube outlet section 7112 in real time and feeds it back to the coolant delivery system 72; the coolant delivery system 72 controls the amount of coolant entering the heat exchanger 71 by adjusting the opening of the electromagnetic regulating valve according to the received temperature signal, so as to maintain the airflow temperature in the loop at T.

[0052] The temperature sensor collects the airflow temperature at the inlet and outlet of the heat exchanger 71 in real time, so that the coolant delivery system 72 can adjust the opening of the electromagnetic regulating valve according to the temperature signal to achieve precise control of the coolant flow rate. This allows the heat exchange efficiency to be dynamically adjusted according to the actual temperature of the airflow, so that the airflow temperature in the loop can be quickly stabilized at the set value, thereby achieving the goal of small temperature fluctuation range.

[0053] It should be noted that the coolant delivery system 72 uses a relatively conventional water-cooled cooling device, which will not be described in detail. It is sufficient that it can continuously supply coolant (water) to the heat exchanger 71.

[0054] Example 3: This embodiment is an improvement based on Embodiment 1 or 2.

[0055] In this embodiment, the comparison device further includes a measurement and control system. The measurement and control system consists of a pressure sensor 201, a humidity sensor 202, a data acquisition unit 203, and a PC control module 204. The pressure sensor 201 has at least two sets, installed at the outlet of the standard access point 2 and the inlet of the inspection access point 3, respectively, to simultaneously collect pressure values ​​at both locations. The humidity sensor 202 collects the relative humidity of the airflow within the loop 1. The data acquisition unit 203 is connected to the standard meter module 5, the meter under test module 6, the temperature sensor 8, and the pressure sensor 201 via a CAN bus to achieve real-time data transmission. The PC control module 204 has a built-in data processing unit, realizing integrated functions for dual-meter comparison, temperature and pressure correction, error calculation, result judgment, and report generation.

[0056] Among them, pressure sensor 201 and humidity sensor 202 collect pressure and humidity data in loop 1 in real time, providing parameters for temperature and pressure correction of flow data, enabling flow data to be converted to standard operating conditions and ensuring the comparability of calibration results under different environments; data acquisition unit 203 realizes real-time and high-speed transmission of various types of data through CAN bus, with high transmission efficiency and strong anti-interference ability, avoiding loss or distortion during data transmission; the automated data processing function of PC control module 204 realizes full automation of dual standard table comparison, temperature and pressure correction, error calculation, and result judgment, eliminating the need for manual calculation, greatly improving the efficiency of calibration work, and avoiding errors caused by manual calculation; the function of automatically generating calibration reports makes the recording and archiving of calibration results more standardized and convenient, meeting the standardization requirements of metrology and testing.

[0057] The gas positive pressure dual standard meter comparison device in this embodiment operates under positive pressure cyclic conditions. The specific workflow is as follows: Air supply preparation: Start the air supply system. The airflow generated by the air compressor is dried and dehydrated by the refrigerated dryer and then enters the pressure stabilizing tank for pressure stabilization. The pressure stabilizing tank delivers the airflow that meets the pressure requirements to the air supply port of the heat exchanger of the cooling system. Airflow mixing and temperature control: The air inlet of the heat exchanger delivers fresh airflow to the airflow mixing chamber, where it is fully mixed with the circulating airflow entering from the loop circulation inlet. The mixed airflow then enters the heat exchange tubes of the heat exchanger. The coolant delivery system of the cooling system controls the coolant flow rate through an electromagnetic regulating valve, and exchanges heat with the airflow in the heat exchange tubes to adjust the airflow temperature to the set constant temperature value. Standard flow rate acquisition and verification: After being kept at constant temperature, the airflow enters the standard access point of the loop. Two standard gauges of the same specification on the standard access point simultaneously acquire the flow rate data of the airflow. The data is transmitted to the measurement and control system. The measurement and control system compares and verifies the two sets of data, calculates the relative deviation, and determines the validity of the benchmark before taking the standard flow rate value. Calibration of the tested instrument: The airflow through the standard through-hole enters the test through-hole of the loop, and the airflow flows through the tested instrument module on the test channel. The tested instrument module collects the flow data and transmits it to the measurement and control system. Airflow circulation: The airflow that has passed the inspection returns to the heat exchanger circulation inlet of the cooling system and mixes with the new airflow supplied by the air supply system to complete one cycle. The continuous airflow circulation in the loop ensures the stability of the positive pressure condition. Excess airflow is discharged through the exhaust structure of the loop to maintain the pressure balance in the loop. Data processing and result determination: The pressure and humidity sensors of the measurement and control system collect pressure and humidity data in the loop at the standard and test ports in real time. The data acquisition unit transmits the standard meter data, the test meter data, and the temperature, pressure, and humidity data to the PC control module. After correcting the data for temperature and pressure, the PC control module calculates the flow error between the test meter and the standard meter, determines whether the test meter is qualified based on the error value, and automatically generates a calibration report containing all data and determination results.

[0058] Test 1: Taking the calibration of a DN100, 1.0 class turbine flow meter as an example.

[0059] Step 1: Equipment Debugging and Parameter Setting. Fix the test module 6 (DN100 turbine flow meter) to the third inspection channel 33 via the flange. Replace the matching sealing gasket, tighten the bolts, and then perform an airtightness test. Introduce 0.6MPa compressed air into loop 1 and maintain for 30 minutes. If the pressure drop is ≤0.005MPa, the airtightness is confirmed to be qualified. Set the calibration parameters in the PC control module 204: pressure 0.6MPa, temperature 25℃, and 3 calibration flow points (100m³ / h). 3 / h, 300m 3 / h, 650m 3 / h).

[0060] Step 2: Start the air supply system 4. The compressed air generated by the air compressor 41 is dried by the refrigerated dryer 42 and then enters the pressure stabilizing tank 43 to stabilize the pressure before being delivered to the loop 1. Start the cooling system. The temperature control module 10 stabilizes the airflow temperature in the loop 1 at 25℃±0.5℃ based on the feedback from the temperature sensor 8, and adjusts the opening of the electromagnetic regulating valve 9. After the temperature and pressure have stabilized for 3 minutes, start the measurement and control system.

[0061] Step 3: Dual standard meter comparison and benchmark establishment. The PC control module 204 controls the opening of the solenoid valve of the second standard channel 22, and the two DN100 turbine flow meters (standard meter module 5) synchronously collect flow data. At 300m... 3 After the flow rate stabilizes for 2 minutes, collect 3 sets of data continuously: Q 1-1 =299.8m 3 / h、Q1-2 =300.1m 3 / h、Q 1-3 =299.9m 3 / h, mean Q 1均 =299.93m 3 / h;Q 2-1 =300.0m 3 / h、Q 2-2 =300.2m 3 / h、Q 2-3 =299.9m 3 / h, mean Q 2均 =300.03m 3 / h. Calculate the relative deviation between the two tables. Δ = |299.93 - 300.03| / [(299.93 + 300.03) / 2] × 100% = 0.033% ≤ 0.1%, the criterion is deemed valid, and Q is taken. 标均 =(299.93+300.03) / 2=299.98m 3 / h serves as the standard reference for this flow rate point.

[0062] Step 4: Calibration and Error Calculation of the Test Module. Keeping the operating conditions unchanged, collect three sets of flow data from the test module 6: Q 被-1 =300.5m 3 / h、Q 被-2 =300.3m 3 / h、Q 被-3 =300.4m 3 / h, mean Q 被均 =300.4m 3 / h. The PC control module 204, combining data from pressure sensor 201 (measured pressure 0.598 MPa) and temperature sensor 8 (measured temperature 24.8℃), performs temperature and pressure correction according to the ideal gas law, resulting in the corrected standard flow rate Q. 标修 =300.05m 3 / h. The relative error δ = |300.4 - 300.05| / 300.05 × 100% = 0.117% ≤ 1.0%, so the flow rate point is calibrated successfully.

[0063] Step 5: Complete 100m following the above procedure. 3 / h, 650m 3 The calibration of the / h flow rate point yielded relative errors of 0.09% and 0.13%, respectively, both meeting the requirements of the Class 1.0 gauge under test. The PC control module 204 automatically generates a calibration report, including equipment parameters, operating data, dual gauge comparison results, errors at each flow rate point, and judgment conclusions, and supports printing and archiving.

[0064] Example 4: This embodiment expands upon embodiments one, two, and three by extending the gas supply system 4 and the standard meter module 5 to achieve flow meter calibration for three common industrial gases: air, natural gas, and nitrogen. The specific extensions are as follows: The gas supply system 4 also includes a media switching module: comprising a natural gas storage tank, a nitrogen storage tank, and a dedicated media purification module, which switches between the system and the existing compressed air system via an electromagnetic three-way valve. The natural gas purification module is equipped with a desulfurization filter (desulfurization efficiency ≥99.5%) and a dehydration device (dew point ≤-30℃); the nitrogen purification module is equipped with an oil removal filter (filtration accuracy ≤0.01μm) to ensure that the purity of different media meets calibration requirements.

[0065] The standard meter module 5 adds a fourth standard channel, which is for DN150 pipelines and is equipped with two DN150 ultrasonic flow meters (accuracy class 0.2). It is not affected by the density and viscosity of the medium and is suitable for calibration of media with large differences in viscosity, such as natural gas and air.

[0066] Test 2 Taking the calibration of a DN200 ultrasonic flow meter for natural gas as an example.

[0067] Step 1: Medium Switching and System Debugging. In PC control module 204, select "Natural Gas" as the medium. The electromagnetic three-way valve will automatically switch to the natural gas storage tank. Start the natural gas purification module. Wait until the medium purity meets the standard (sulfur content ≤ 10 mg / m³). 3 Moisture content ≤ 5 mg / m³ 3 After that, set the calibration pressure to 0.8 MPa and the temperature to 20°C.

[0068] Step 2: Standard Channel Selection and Benchmark Determination. Select the first standard channel 21 (two DN200 turbine flow meters), and determine the 800m... 3 The standard benchmark Q for the / h flow point 标均 =799.85m 3 / h, the relative deviation between the two meters Δ=0.04%≤0.1%.

[0069] Step 3: Calibration and Result Determination of the Test Instrument. Install the DN200 ultrasonic test instrument module 6 on the first inspection channel 31 and complete the 800m... 3 / h, 1500m 3 / h, 2500m 3 The calibration of the three flow points at / h showed relative errors of 0.15%, 0.12%, and 0.18%, respectively, all of which met the allowable error requirement of level 1.0, and the calibration was deemed qualified.

[0070] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A gas positive pressure dual standard meter comparison device, characterized in that, Comprising: A closed loop (1) with a standard through position (2) and an inspection through position (3) thereon; An air supply system (4) for conveying air flow into the loop (1) to make the air flow circulate in the loop (1); A standard meter module (5) connected in series to the standard through position (2) for collecting the standard air flow rate value passing through the standard through position (2); And a meter under test module (6) connected in series to the inspection through position (3), and the meter under test module (6) is calibrated by the air flow rate passing through the inspection through position (3); Wherein, the standard through position (2) includes two standard meters of the same specification, and the two standard meters are connected in series to the standard through position (2), and synchronously collect flow data for mutual comparison and verification to calibrate the meter under test module (6).

2. The gas positive pressure dual standard meter comparison device as described in claim 1, characterized in that, The standard through position (2) includes: a first standard channel (21), a second standard channel (22) and a third standard channel (23) connected in parallel with each other, and two of the said standard meters are provided on each of the first standard channel (21), the second standard channel (22) and the third standard channel (23); Wherein, the two standard meters on the first standard channel (21) are both DN200 turbine flow meters; the two standard meters on the second standard channel (22) are both DN100 roots flow meters; the two standard meters on the third standard channel (23) are both DN50 roots flow meters.

3. The gas positive pressure dual standard meter comparison device as described in claim 2, characterized in that, The first standard channel (21) is a DN200 pipeline; the second standard channel (22) is a DN100 pipeline; the third standard channel (23) is a DN50 pipeline.

4. The gas positive pressure dual standard meter comparison device as described in claim 3, characterized in that, The inspection through position (3) includes: a first inspection channel (31), a second inspection channel (32), a third inspection channel (33), a fourth inspection channel (34) and a fifth inspection channel (35) connected in parallel with each other; Wherein, the first inspection channel (31) is a DN200 pipeline; the second inspection channel (32) is a DN150 pipeline; the third inspection channel (33) is a DN100 pipeline; the fourth inspection channel (34) is a DN80 pipeline; the fifth inspection channel (35) is one of the pipelines of DN50, DN40, DN32, DN25, DN20, DN15; Wherein, the meter under test module (6) can be arranged on the first inspection channel (31), the second inspection channel (32), the third inspection channel (33), the fourth inspection channel (34) or the fifth inspection channel (35).

5. The gas positive pressure dual standard meter comparison device as described in claim 1, characterized in that, The air supply system (4) includes: an air compressor (41); a refrigeration dryer (42) connected to the air compressor (41) and a pressure stabilizing tank (43) connected to the refrigeration dryer (42); Wherein, the pressure stabilizing tank (43) conveys the air flow with stabilized pressure into the loop (1).

6. The gas positive pressure dual standard meter comparison device as described in claim 1, characterized in that, Further comprising: A cooling system for adjusting the temperature of the air flow entering the loop (1) from Ta to T, Ta < T, so as to keep the air flow temperature in the loop (1) constant.

7. The gas positive pressure dual standard meter comparison device as described in claim 6, characterized in that, The cooling system includes a heat exchanger (71) and a coolant delivery system (72) for continuously delivering coolant into the heat exchanger (71). The heat exchanger (71) includes: The outer cylinder (711) has a tube-side inlet section (7111) and a tube-side outlet section (7112) at its two ends respectively. The outer wall of the outer cylinder (711) is also provided with a gas supply port (7113) leading to the tube-side inlet section (7111). The outer wall of the outer cylinder (711) is also provided with a liquid inlet (7114) and a liquid outlet (7115) near both ends. The liquid inlet (7114) and the liquid outlet (7115) are both connected to the inner cavity of the outer cylinder (711). The mounting plate (712) has two pieces, which are respectively set in the inlet section (7111) and the outlet section (7112) of the tube, to seal the inner cavity of the outer cylinder (711); And heat exchange tubes (713) are horizontally arranged in the inner cavity of the outer cylinder (711), and their two ends pass through the two mounting plates (712) respectively; there are a plurality of heat exchange tubes (713), which are distributed at intervals in the inner cavity of the outer cylinder (711), and the gap between each heat exchange tube (713) forms a coolant chamber for coolant flow; The outer cylinder (711) is connected in series with the annular channel. One end of the tube inlet section (7111) forms the circulation inlet of the airflow in the annular channel, and one end of the tube outlet section (7112) forms the circulation outlet of the airflow in the annular channel. An airflow mixing chamber (7116) is formed in the tube inlet section (7111) and is connected to the air supply port (7113) and the circulation inlet. The airflow generated by the air supply system flows to the air supply port (7113). The airflow entering from the air inlet (7113) and the airflow entering from the circulation inlet enter the airflow mixing chamber (7116) and mix before being discharged from the other end of the tube inlet section (7111) and entering the heat exchange tube (713), and finally being discharged from the circulation outlet.

8. The gas positive pressure dual standard meter comparison device as described in claim 7, characterized in that, The inlet section (7111) includes: a first straight pipe section (71111), an enlarged diameter section (71112), and a second straight pipe section (71113) connected in sequence; the diameter of the second straight pipe section (71113) is larger than the diameter of the first straight pipe section (71111); The inlet section (7111) of the tube also includes an annular sleeve (71114) sleeved on the outer surface of the expansion section (71112), the air inlet (7113) is disposed on the annular sleeve (71114), an air inlet chamber is formed between the inner wall of the annular sleeve (71114) and the outer wall of the expansion section (71112), and a number of through air holes (71115) are also provided on the outer wall of the expansion section (71112), and the inner cavity of the expansion section (71112) forms the airflow mixing chamber (7116).

9. The gas positive pressure dual standard meter comparison device as described in claim 7, characterized in that, The cooling system also includes: a temperature sensor (8) and an electromagnetic regulating valve (9); The temperature sensor (8) collects the airflow temperature in the inlet section and outlet section of the tube in real time and feeds it back to the coolant delivery system. The coolant delivery system controls the amount of coolant entering the heat exchanger by adjusting the opening of the electromagnetic regulating valve (9) according to the received temperature signal, so that the airflow temperature in the loop (1) is maintained at T.

10. The gas positive pressure dual standard meter comparison device as described in claim 1, characterized in that, Also includes: The measurement and control system includes a pressure sensor (201), a humidity sensor (202), a data acquisition unit (203), and a PC control module (204). The pressure sensor (201) is used to collect the real-time pressure of the standard pass (2) and the test pass (3); the humidity sensor (202) is used to collect the relative humidity of the airflow in the loop (1); the data acquisition unit (203) transmits data in real time with the standard meter module (5), the meter under test module (6), and various sensors via the CAN bus; the PC control module (204) has built-in data processing software to automatically complete the comparison of the dual standard meters and the meter under test module (6), temperature and pressure correction, error calculation, result judgment, and report generation.

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