Compound gas flow standard device and its calibration method

Abstract

The present application belongs to the technical field of natural gas flow meter real flow verification / calibration, and specifically discloses a composite gas flow standard device and a verification method thereof, which comprises an inlet pipeline, an outlet pipeline, a verification pipeline, a compensation loading pipeline, a pressure regulating system, a standard flow meter group and a flow regulating system; the two ends of the compensation loading pipeline are connected in parallel to the verification pipelines on the two sides of the standard flow meter group and the flow meter to be verified; the two sides of the compensation loading pipeline are respectively communicated with the inlet pipeline and the outlet pipeline through pipelines, and valve E and valve F are respectively installed on the pipelines on the two sides of the compensation loading pipeline; an adjusting pipeline is communicated between the two sides of the compensation loading pipeline; valve A and valve B are installed on the two sides of the verification pipeline, and valve C and valve D are respectively installed on the two ends of the compensation loading pipeline; a driving mechanism is installed on the compensation loading pipeline. The present application can compensate the maximum adjustable flow upper limit value, so that it is not affected by the working condition changes of high and low pressure gas pipelines.

Description

Technical Field

[0001] This invention relates to the field of actual flow verification / calibration technology for natural gas flow meters, specifically to a composite gas flow standard device and its verification method. Background Technology

[0002] In natural gas flow metering, to ensure accuracy, large-diameter (DN50 and above) natural gas flow meters are typically verified / calibrated using actual flow, i.e., verified / calibrated with natural gas (hereinafter referred to as verification). Verification of natural gas flow meters mainly utilizes various forms of gas flow standard devices. Currently, the most mainstream is the direct-discharge standard meter method for gas flow standard devices. For example... Figure 1 Its working principle is to utilize the pressure difference between the high-pressure gas pipeline and the low-pressure gas pipeline to generate flow. Gas flows out from the high-pressure gas pipeline, enters through the inlet pipeline, and after passing through the pressure regulating system, flows to the standard flow meter group (standard meter) and the flow meter under test. After passing through the flow regulating system again, it flows back to the low-pressure gas pipeline through the outlet pipeline. By comparing the gas flow rates through the standard flow meter group and the flow meter under test within the same time period, the indication error of the flow meter under test is obtained, and this indication error is used to determine whether the flow meter under test is qualified.

[0003] In the above-mentioned device, the installation positions of the standard flow meter group and the flow meter under test can be interchanged; the pressure regulating system is used to regulate and stabilize the gas pressure flowing through the standard flow meter group and the flow meter under test to the pressure required for calibration, and the adjustable pressure range is between the pressure of the high-pressure gas transmission pipeline and the low-pressure gas transmission pipeline; the flow regulating system is used to regulate and stabilize the gas flow rate flowing through the standard flow meter group and the flow meter under test to the flow rate required for calibration, and the adjustable flow rate range is determined according to the pressure and flow rate of the high-pressure gas transmission pipeline and the low-pressure gas transmission pipeline.

[0004] In practice, the pressure and flow rate of high-pressure and low-pressure gas pipelines are not constant values. Both are affected by upstream gas supply, downstream user gas consumption, upstream trunk pressure, and downstream user gas pressure. Insufficient upstream gas supply, insufficient downstream user gas consumption, or a small pressure difference between high-pressure and low-pressure pipelines will all lead to a decrease in the maximum adjustable flow rate of the entire calibration pipeline. This decrease prevents the calibration of large-diameter flow meters at high flow points. These flow meters will have to wait and be recalibrated at a later date. If the maximum adjustable flow rate fails to meet requirements for an extended period, these flow meters will remain unused, causing a backlog. This can result in financial losses for customers who urgently need the flow meters. Furthermore, the inability to retrieve the flow meters promptly will reduce customer satisfaction. Therefore, addressing the issue of the decrease in the maximum adjustable flow rate of the calibration pipeline due to changes in the operating conditions of high and low pressure gas pipelines has become an urgent need for improvement in the current calibration system. Summary of the Invention

[0005] This invention provides a composite gas flow standard device and method, which aims to compensate for the maximum adjustable flow rate upper limit, so that it is not affected by changes in the operating conditions of high and low pressure gas pipelines.

[0006] This invention is achieved through the following technical solution: a composite gas flow standard device, comprising an inlet pipeline, an outlet pipeline, a calibration pipeline, and a pressure regulating system, a standard flow meter group, and a flow regulating system installed on the calibration pipeline. The flow meter under test is installed on the calibration pipeline and located between the pressure regulating system and the flow regulating system. The two ends of the calibration pipeline are respectively connected to the inlet pipeline and the outlet pipeline. The device also includes a compensation loading pipeline, the two ends of which are connected in parallel to the calibration pipeline on both sides of the standard flow meter group and the flow meter under test. The two sides of the compensation loading pipeline are respectively connected to the inlet pipeline and the outlet pipeline via pipelines, and valves E and F are respectively installed on the pipelines on both sides of the compensation loading pipeline. A regulating pipeline connects the two sides of the compensation loading pipeline. Valves A and B are installed on both sides of the calibration pipeline, and valves C and D are respectively installed at the two ends of the compensation loading pipeline. A drive mechanism for generating compensation flow is installed on the compensation loading pipeline.

[0007] Furthermore, it also includes two connecting pipes, one end of which is connected to the air inlet pipe and the air outlet pipe respectively, and the other end of which is connected to both sides of the compensation loading pipe respectively. The valve E and the valve F are respectively installed on the connecting pipes on both sides of the compensation loading pipe.

[0008] Furthermore, a flow-dividing regulation system is installed on the regulating pipeline, and the flow-dividing regulation system includes one or more regulating valves.

[0009] Furthermore, the regulating pipeline and the connecting pipeline are connected to the compensation loading pipeline, and both connecting pipelines are connected to both sides of the calibration pipeline.

[0010] Furthermore, both valves C and D are located close to the calibration pipeline.

[0011] Furthermore, valve A is located on the calibration pipeline between the pressure regulating system and the compensation loading pipeline, and valve B is located on the calibration pipeline between the flow regulating system and the compensation loading pipeline.

[0012] Furthermore, valves A, B, and C are all on / off valves, while valves D, E, and F are all regulating valves.

[0013] Furthermore, the drive mechanism is a centrifugal compressor.

[0014] Furthermore, a monitoring flow meter is installed on the compensation loading pipeline.

[0015] A calibration method for a composite gas flow standard device, characterized in that the flow meter under test is calibrated using any of the composite gas flow standard devices described above.

[0016] Furthermore, it includes three working modes: direct flow mode, compensation flow loading mode, and loop mode.

[0017] The direct discharge working mode includes the following steps: opening valves A and B, closing valves C, D, E, and F, and the gas input from the inlet pipe passes sequentially through the pressure regulating system, the standard flow meter group, the flow meter under test, and the flow regulating system before being discharged through the outlet pipe;

[0018] The compensation traffic loading mode includes the following steps:

[0019] S1, Pre-adjust compensation flow rate, the regulating pipeline and the compensation loading pipeline form an regulating loop, start the drive mechanism to drive the gas flow in the pipeline to generate compensation flow rate, and adjust the pressure and flow rate to the pressure and compensation flow rate required for the verification in the regulating loop;

[0020] S2, Load compensation flow rate, the compensation flow rate adjusted in the adjustment loop is loaded into the calibration pipeline;

[0021] The loop working mode includes the following steps: close valves A and B, open valves C and D, at which time the compensation loading pipeline and the calibration pipeline form a loop pipeline, and start the drive mechanism to load the compensation flow into the calibration pipeline.

[0022] Furthermore, during the pre-adjustment compensation flow process, valves E and F are normally closed. When it is necessary to increase the pressure in the regulating loop, valve E is opened; when it is necessary to decrease the pressure in the regulating loop, valve F is opened.

[0023] Furthermore, in the loop operation mode, valve E is opened when it is necessary to increase the pressure in the loop pipeline; valve F is opened when it is necessary to decrease the pressure in the loop pipeline.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] In this invention, the inlet and outlet pipelines are connected to the high-pressure and low-pressure gas transmission pipelines, respectively. By setting up a compensation loading pipeline and a regulating pipeline, the regulating pipeline and the compensation loading pipeline form a regulating loop. When changes in the operating conditions of the high-pressure and low-pressure gas transmission pipelines cause a decrease in the maximum adjustable flow rate of the calibration pipeline, the pressure in the regulating loop formed by the regulating pipeline and the compensation loading pipeline is adjusted to the required calibration pressure through the coordination of various valves. Then, by activating the drive mechanism, flow is generated in the regulating loop, adjusting the flow rate in the regulating loop to the required compensation flow rate of the calibration pipeline. After the pressure and flow rate in the regulating loop stabilize, the compensation flow rate in the regulating loop is applied to the calibration pipeline, thereby achieving the required flow rate for calibrating a large-diameter flowmeter at its maximum flow point. This achieves the goal of compensating for the maximum adjustable flow rate limit, making it unaffected by changes in the operating conditions of the high-pressure and low-pressure gas transmission pipelines.

[0026] This invention has three working modes: direct discharge mode, compensated flow loading mode, and loop mode. During the actual verification process, the three modes can be flexibly switched according to the actual testing requirements of the flowmeter under test and the operating conditions of high and low pressure gas pipelines. It is convenient and flexible to use and can meet a variety of usage requirements.

[0027] The composite gas flow standard device of the present invention can efficiently carry out calibration work in the direct discharge mode under good operating conditions, and can also activate the compensation system to cope with extreme operating conditions, thus having good adaptability. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 A schematic diagram of the process flow of a gas flow standard device using the direct-discharge standard meter method in the prior art;

[0030] Figure 2 This is a schematic diagram of the direct discharge working mode in an embodiment of a composite gas flow standard device of the present invention;

[0031] Figure 3 This is a schematic diagram of the pre-adjustment compensation flow rate in an embodiment of a composite gas flow standard device of the present invention;

[0032] Figure 4 This is a schematic diagram of the process of loading compensation flow in an embodiment of a composite gas flow standard device of the present invention;

[0033] Figure 5 This is a schematic diagram of the loop operation mode in an embodiment of a composite gas flow standard device of the present invention.

[0034] The attached diagram shows the markings and corresponding component names:

[0035] 1. High-pressure gas transmission pipeline; 2. Low-pressure gas transmission pipeline; 101. Inlet gas pipeline; 201. Outlet gas pipeline; 3. Pressure regulation system; 4. Standard flow meter group; 5. Flow meter under test; 6. Flow regulation system; 7. Diversion regulation system; 8. Monitoring flow meter; 9. Centrifugal compressor; 10. Calibration pipeline; 11. Connecting pipeline; 12. Compensation loading pipeline; 13. Regulation pipeline. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0037] like Figure 2 As shown, as one embodiment of this application, a composite gas flow standard device is provided, including an inlet pipe 101, an outlet pipe 201, a calibration pipe 10, and a pressure regulating system 3, a standard flow meter group 4, and a flow regulating system 6 installed on the calibration pipe 10. The flow meter under test 5 is installed on the calibration pipe 10 and is located between the pressure regulating system 3 and the flow regulating system 6. The positions of the flow meter under test 5 and the standard flow meter group 4 can be interchanged. The standard flow meter group 4 (standard meter) is the measurement standard used to calibrate the flow meter. It can be a single standard flow meter or a combination of several standard flow meters.

[0038] The intake pipe 101 is connected to the high-pressure gas transmission line 1, and the outlet pipe 201 is connected to the low-pressure gas transmission line 2.

[0039] The two ends of the calibration pipeline 10 are connected to the inlet pipeline 101 and the outlet pipeline 201 respectively. A composite gas flow standard device also includes a compensation loading pipeline 12. The two ends of the compensation loading pipeline 12 are connected in parallel to the calibration pipeline 10 on both sides of the standard flow meter group 4 and the flow meter under test 5. The compensation loading pipeline 12 and the calibration pipeline 10 form a loop pipeline.

[0040] The two sides of the compensation loading pipeline 12 are respectively connected to the inlet pipeline 101 and the outlet pipeline 201 through pipelines, and valves E and F are respectively installed on the pipelines on both sides of the compensation loading pipeline 12; a regulating pipeline 13 is connected between the two sides of the compensation loading pipeline 12, and a regulating loop is formed between the regulating pipeline 13 and the compensation loading pipeline 12. Specifically, a composite gas flow standard device also includes two connecting pipelines 11. One end of the two connecting pipelines 11 is connected to the inlet pipeline 101 and the outlet pipeline 201 respectively, and the other end of the two connecting pipelines 11 is connected to both sides of the compensation loading pipeline 12 respectively. In this embodiment, the regulating pipeline 13 and the connecting pipeline 11 are connected to the compensation loading pipeline 12 through a four-way pipe, and both connecting pipelines 11 are connected to both sides of the calibration pipeline 10 through a three-way pipe. Valves E and F are respectively installed on the connecting pipelines 11 on both sides of the compensation loading pipeline 12.

[0041] Valves A and B are installed on both sides of the calibration pipeline 10, and valves C and D are installed at both ends of the compensation loading pipeline 12. Valve A is located on the calibration pipeline 10 between the pressure regulating system 3 and the compensation loading pipeline 12, and valve B is located on the calibration pipeline 10 between the flow regulating system 6 and the compensation loading pipeline 12. Valves C and D are both located close to the calibration pipeline 10, which can better control the flow in the flow compensation loading pipeline 12 and the calibration pipeline 10 and reduce interference. A drive mechanism for generating compensation flow is installed on the compensation loading pipeline 12. The drive mechanism is a centrifugal compressor 9, which is used to drive the gas flow in the pipeline to generate compensation flow.

[0042] In this invention, valves A, B, and C are all on / off valves, and valves D, E, and F are all regulating valves. The on / off valves are used to switch processes. Different workflows are obtained by combining valves with different on / off states. The detailed working conditions of each process will be described in the embodiments. The regulating valves are used for working conditions that require slow opening, slow closing, or long-term half-opening.

[0043] As one embodiment of this application, a monitoring flow meter 8 is installed on the compensation loading pipeline 12 to monitor the magnitude of the compensation flow when the centrifugal compressor 9 adjusts the compensation flow, so as to facilitate adjustment. After the monitoring flow meter 8 detects the flow magnitude in the pipeline, the centrifugal compressor 9 can be manually operated to adjust the flow magnitude, or the centrifugal compressor 9 can be automatically controlled by a controller and computer program to adjust the flow. This invention does not limit the scope of the invention.

[0044] In another embodiment of this application, a flow diversion control system 7 is installed on the regulating pipeline 13, and the flow diversion control system 7 includes one or more regulating valves.

[0045] The pressure regulating system 3 is used to regulate and stabilize the gas pressure flowing through the standard flow meter group 4 and the flow meter under test 5 to the pressure required for calibration, and consists of one or more regulating valves; the flow regulating system 6 is used to regulate and stabilize the gas flow through the standard flow meter group 4 and the flow meter under test 5 to the flow rate required for calibration, and consists of one or more regulating valves.

[0046] Like pressure regulation system 3 and flow regulation system 6, flow control system 7 consists of one or more parallel opening regulating valves. Their basic principle is that the larger the valve opening, the more gas flows through; the smaller the valve opening, the less gas flows through. These three systems have similar structures, but in this invention, they are named differently based on their different effects on the airflow conditions (pressure and flow rate).

[0047] The composite gas flow standard device of the present invention also includes some auxiliary equipment such as pressure sensors and temperature sensors, but these devices are not related to the innovation of the present invention and belong to the structures that can be used by those skilled in the art according to the actual situation, and will not be described in detail here.

[0048] As another embodiment of this application, a calibration method for a composite gas flow standard device is also disclosed. The composite gas flow standard device described above is used to calibrate the flow meter 5 under test. Specifically, it includes three working modes: direct discharge working mode, compensation flow loading mode, and loop working mode.

[0049] 1. When the operating conditions of high-pressure gas pipeline 1 and low-pressure gas pipeline 2 are good and the maximum adjustable flow rate is high, the direct discharge working mode can be used directly. Specifically, the direct discharge working mode includes the following steps: Figure 2As shown, valves A and B are opened, and valves C, D, E, and F are closed. The gas flow direction is: high-pressure gas pipeline 1 → inlet pipeline 101 → pressure regulating system 3 → standard flow meter group 4 (standard meter) → flow meter under test 5 → flow regulating system 6 → outlet pipeline 201 → low-pressure gas pipeline 2. The calibration work is completed by the direct discharge process of the gas input from high-pressure gas pipeline 1 through inlet pipeline 101, passing through pressure regulating system 3, standard flow meter group 4, flow meter under test 5, flow regulating system 6, and then through outlet pipeline 201 into low-pressure gas pipeline 2. This process is highly efficient and energy-saving.

[0050] In the straight-line working mode of this invention:

[0051] When the pressure regulating system 3 (equivalent to an opening control valve) increases its opening, the amount of gas flowing through it increases, resulting in higher downstream gas flow rate and pressure; conversely, when its opening decreases, the amount of gas flowing through it decreases, resulting in lower downstream gas flow rate and pressure. The pressure regulating system 3 primarily affects the operating conditions of the gas flow in the calibration pipeline 10 through pressure.

[0052] The flow regulation system 6 (equivalent to an opening control valve) increases the amount of gas flowing through when its opening increases, resulting in increased gas flow and decreased pressure upstream; conversely, it decreases the amount of gas flowing through when its opening decreases, resulting in decreased gas flow and increased pressure upstream. The flow regulation system 6 primarily affects the operating conditions of the gas flow in the calibration pipeline 10 by its flow rate.

[0053] The pressure regulation system 3 and the flow regulation system 6 must be used together to ensure that the airflow in the calibration pipeline 10 reaches the required pressure and flow rate.

[0054] 2. When changes in the operating conditions of high-pressure gas pipeline 1 and low-pressure gas pipeline 2 cause a decrease in the maximum adjustable flow rate of calibration pipeline 10, centrifugal compressor 9 can be turned on to obtain the required compensation flow rate. This compensation flow rate is then applied to calibration pipeline 10 to achieve the required calibration flow rate. This method can also complete the calibration of large-diameter flow meters. Specifically:

[0055] The compensated traffic loading mode includes the following steps:

[0056] S1, pre-adjusted compensation flow rate, such as Figure 3 As shown, the regulating pipeline 13 and the compensating loading pipeline 12 form a regulating loop. Figure 3 (The purple dotted line in the middle) Start the centrifugal compressor 9 to drive the gas flow in the pipeline, generating a compensating flow rate. Adjust the pressure and flow rate in the regulating loop to the pressure and compensating flow rate required for the calibration. Specifically:

[0057] exist Figure 2Based on the direct discharge working mode, the regulating valve in the diversion regulating system 7 is fully opened to connect the compensation flow with the regulating loop. During the pre-regulation of the compensation flow, valves E and F are normally closed and are only opened when pressure needs to be regulated. When it is necessary to increase the pressure in the regulating loop, valve E is opened; when it is necessary to decrease the pressure in the regulating loop, valve F is opened and the centrifugal compressor 9 is started to generate the compensation flow in the regulating loop.

[0058] In this process, the pressure in the regulating loop is adjusted to the pressure required for the test by valves E and F, and the flow rate is adjusted to the compensation flow rate required for the test by centrifugal compressor 9. After the flow meter 8 detects the flow rate in the regulating loop, the flow rate can be adjusted manually by operating centrifugal compressor 9 or automatically by controlling centrifugal compressor 9 through computer controller.

[0059] Valve E and valve F can be adjusted manually or intelligently via a computer controller; this invention does not impose any limitations on these adjustments.

[0060] For example, when a maximum flow rate of 6000 m3 / h is required during calibration, but the current operating conditions of high-pressure gas pipeline 1 and low-pressure gas pipeline 2 can only provide a maximum flow rate of 5000 m3 / h, a compensation flow rate of 1000 m3 / h is required. This compensation flow rate of 1000 m3 / h is pre-adjusted to a stable state in the compensation flow pre-adjustment loop to prepare for the final completion of compensation.

[0061] S2, load compensation traffic, such as Figure 4 As shown, the compensation flow rate adjusted within the regulating loop will be applied to the calibration pipeline 10. Specifically:

[0062] Based on step S1, open valve C, slowly open valve D, and slowly close the flow diversion control system 7. Gradually load the flow in the compensation flow pre-adjustment loop into the calibration pipeline 10. The flow diversion control system 7 may not be completely closed, allowing for fine-tuning of the flow in the calibration pipeline 10. Specifically, the flow diversion control system 7 consists of one or more parallel opening control valves, with three states: fully open, fully closed, and open according to the opening degree. Under the current operating condition, valves A, B, C, and D are open, while valves E and D are closed. When valve F is closed, if the flow rate through the test pipeline 10 is too high, one or more regulating valves in the diversion system 7 can be opened appropriately to allow a portion of the upstream airflow to flow downstream through the diversion system 7 pipeline, thereby reducing the flow rate through the test pipeline 10. For example, if the flow rate through the test pipeline 10 is 6100 m3 / h, the diversion system 7 can be opened appropriately to allow 100 m3 / h of airflow to flow through the diversion system 7 pipeline, at which point the flow rate through the test pipeline 10 will be reduced to 6000 m3 / h.

[0063] Before the diversion and regulation system 7 is closed, only a portion of the compensation flow flows into the calibration pipeline 10; only when the diversion and regulation system 7 is completely closed does the compensation flow flow into the calibration pipeline 10.

[0064] In this embodiment, slowly opening valve D and slowly closing the flow control system 7 are to prevent the air flow through the flow meter from increasing too rapidly in a short period of time, causing airflow impact and damaging the flow meter. "Slow" is an operation to protect the flow meter.

[0065] 3. When high-pressure gas pipeline 1 and low-pressure gas pipeline 2 cannot supply gas due to special circumstances such as maintenance or pigging, this device can activate the loop operation mode. The loop operation mode includes the following steps: Figure 5 As shown, valves A and B are closed, and valves C and D are opened. At this time, the compensation loading pipeline 12 and the calibration pipeline 10 form a loop pipeline. Figure 5 (The purple dotted line in the middle) Activate the drive mechanism to load the compensation flow into the calibration pipeline 10;

[0066] Gas flow path: centrifugal compressor 9 → monitoring flow meter 8 → standard flow meter group 4 (standard meter) → flow meter under test 5 → centrifugal compressor 9. This can also complete the calibration of some flow meters.

[0067] In the loop operation mode, valves E and F are normally closed. When it is necessary to increase the pressure in the loop pipeline, valve E is opened; when it is necessary to decrease the pressure in the loop pipeline, valve F is opened. Specifically: when the loop is closed, the pressure in the loop pipeline is constant. When it is necessary to increase the pressure, regulating valve E is opened, and gas enters from the upstream high-pressure gas pipeline 1, increasing the pressure in the loop pipeline. When it is necessary to decrease the pressure, regulating valve F is opened, and some gas in the loop pipeline flows into the downstream low-pressure gas pipeline 2, decreasing the pressure in the loop pipeline.

[0068] The flow rate in the loop pipeline is regulated by the centrifugal compressor 9. The higher the speed of the centrifugal compressor 9, the faster the flow rate.

[0069] When the high and low pressure gas transmission pipeline 2 cannot provide flow, the loop operation mode can be used for calibration. At this time, the flow in the calibration pipeline 10 is entirely provided by the centrifugal compressor 9, and the flow control system 7 can make fine adjustments to the flow.

[0070] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite gas flow standard device, comprising an inlet pipe, an outlet pipe, a calibration pipe, and a pressure regulating system, a standard flow meter assembly, and a flow regulating system installed on the calibration pipe, wherein the flow meter under test is installed on the calibration pipe and located between the pressure regulating system and the flow regulating system, and both ends of the calibration pipe are respectively connected to the inlet pipe and the outlet pipe, characterized in that, It also includes a compensation loading pipeline, the two ends of which are connected in parallel to the calibration pipelines on both sides of the standard flow meter group and the flow meter under test; the two sides of the compensation loading pipeline are respectively connected to the inlet pipeline and the outlet pipeline through pipelines, and valves E and F are respectively installed on the pipelines on both sides of the compensation loading pipeline; a regulating pipeline connects the two sides of the compensation loading pipeline; valves A and B are installed on both sides of the calibration pipeline, and valves C and D are respectively installed at the two ends of the compensation loading pipeline; a drive mechanism for generating compensation flow is installed on the compensation loading pipeline.

2. The composite gas flow standard device according to claim 1, characterized in that, It also includes two connecting pipes, one end of which is connected to the air inlet pipe and the air outlet pipe respectively, and the other end of which is connected to both sides of the compensation loading pipe respectively. Valve E and valve F are respectively installed on the connecting pipes on both sides of the compensation loading pipe.

3. The composite gas flow standard device according to claim 1, characterized in that, A flow-dividing regulation system is installed on the regulating pipeline, and the flow-dividing regulation system includes one or more regulating valves.

4. A composite gas flow rate standard device according to claim 2, characterized in that, The regulating pipeline and the connecting pipeline are connected to the compensation loading pipeline, and both connecting pipelines are connected to both sides of the calibration pipeline.

5. A composite gas flow standard device according to claim 1, characterized in that, Both valves C and D are located close to the calibration pipeline.

6. A composite gas flow standard device according to claim 1, characterized in that, Valve A is located on the calibration pipeline between the pressure regulating system and the compensation loading pipeline, and valve B is located on the calibration pipeline between the flow regulating system and the compensation loading pipeline.

7. A composite gas flow standard device according to any one of claims 1-6, characterized in that, Valves A, B, and C are all on / off valves, while valves D, E, and F are all regulating valves.

8. A composite gas flow standard device according to any one of claims 1-6, characterized in that, The drive mechanism is a centrifugal compressor.

9. A composite gas flow standard device according to any one of claims 1-6, characterized in that, A flow meter is installed on the compensation loading pipeline.

10. A calibration method for a composite gas flow standard device, characterized in that, The flowmeter under test is calibrated using a composite gas flow standard device as described in any one of claims 1-9.

11. The calibration method for a composite gas flow standard device according to claim 10, characterized in that, It includes three working modes: direct flow mode, compensation flow loading mode, and loop mode. The direct discharge working mode includes the following steps: opening valves A and B, closing valves C, D, E, and F, and the gas input from the inlet pipe passes sequentially through the pressure regulating system, the standard flow meter group, the flow meter under test, and the flow regulating system before being discharged through the outlet pipe; The compensation traffic loading mode includes the following steps: S1, Pre-adjust compensation flow rate, the regulating pipeline and the compensation loading pipeline form an regulating loop, start the drive mechanism to drive the gas flow in the pipeline to generate compensation flow rate, and adjust the pressure and flow rate to the pressure and compensation flow rate required for the verification in the regulating loop; S2, Load compensation flow rate, the compensation flow rate adjusted in the adjustment loop is loaded into the calibration pipeline; The loop working mode includes the following steps: close valves A and B, open valves C and D, at which time the compensation loading pipeline and the calibration pipeline form a loop pipeline, and start the drive mechanism to load the compensation flow into the calibration pipeline.

12. The calibration method for a composite gas flow standard device according to claim 11, characterized in that, During the pre-adjustment compensation flow process, valves E and F are normally closed. When it is necessary to increase the pressure in the regulating loop, valve E is opened; when it is necessary to decrease the pressure in the regulating loop, valve F is opened.

13. The calibration method for a composite gas flow standard device according to claim 11, characterized in that, In the loop operation mode, valve E is opened when it is necessary to increase the pressure in the loop pipeline; valve F is opened when it is necessary to decrease the pressure in the loop pipeline.

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