Double-pipe natural gas flow field testing system and method with adjustable filling pressure

Abstract

The invention discloses a double-pipe natural gas flow field testing system and method with adjustable filling pressure, and belongs to the technical field of natural gas pipeline testing. The system comprises a natural gas pressure regulating system, a particle filling system and a test pipeline which are sequentially connected from natural gas inlet to natural gas outlet, the natural gas pressure regulating system comprises a first-stage pressure regulating system, a second-stage pressure regulating system and a first pressure measuring unit which are connected in series with the test pipeline; the particle filling system comprises a pressure selection device, a particle filling device and a filling pipeline; the test pipeline comprises process pipeline test sections with different calibers and a non-contact test cabin. According to the invention, the filling effect of particle loading devices with different principle structures can be met, the mixed gas can be fully dispersed to all positions in the test pipeline, test experiments are carried out on different process pipelines, and the accuracy of a flow field test result is improved.

Description

Technical Field

[0001] This invention relates to the field of natural gas pipeline testing technology, specifically to a dual-pipe natural gas flow field testing system and method with adjustable injection pressure. Background Technology

[0002] Natural gas is an important clean energy source, and its demand is increasing. The flow of natural gas within pipelines during transportation is of significant research value. Currently, methods for detecting flow fields and velocities include particle imaging velocimetry and laser Doppler velocimetry. Both methods are non-contact tests, requiring illumination of the test area and the presence of tracer particles in the fluid (natural gas) that move with the fluid without interfering with the flow field. During testing, particle imaging velocimetry and laser Doppler velocimetry can obtain flow field information within the pipeline by detecting these tracer particles.

[0003] Numerous researchers both domestically and internationally have conducted extensive experimental studies on natural gas metering using various flow meters. The results show that many factors influence flow meter performance, particularly the different flow regimes created by varying installation conditions. Most flow meter readings are calculated using empirical formulas or mathematical models under ideal flow conditions. However, in practical applications, whether the flow field conditions within the pipe meet the required specifications is crucial for accurate metering. Currently, macroscopic experimental studies cannot intuitively and systematically analyze the impact of natural gas flow regimes within pressurized pipelines. Therefore, more comprehensive and in-depth numerical simulations and visualization experiments are needed to verify and quantitatively analyze the flow patterns and structures generated by typical flow obstructions, identify the influence patterns on the metering performance of typical flow meters, and guide the selection, installation, and use of flow meters in the field, thereby improving the accuracy of natural gas metering in the field.

[0004] Particle imaging velocimetry (LDV / PIV) is an optical measurement technique that integrates flow visualization and quantitative measurement of flow parameters across the entire flow field. The LDV / PIV system combines the advantages of single-point measurement and display measurement techniques, enabling the measurement of transient velocities across a three-dimensional field with minimal flow field interference and high accuracy and resolution. It can measure not only the flow regime within a pipeline but also the flow velocity in different directions. LDV / PIV can be used for testing gas flow regimes within pipelines and for measuring natural gas flow rates. Its primary application is in understanding the flow field distribution of fluids in natural gas pipelines and accurately measuring the flow velocity at various points within the pipeline. Because velocimetry is traceable to time and length, unlike turbine and ultrasonic flow meters which are traceable to time and mass, LDV / PIV technology is essential for in-depth research into the flow field within pipelines and represents a crucial direction for research and development in the field of metrology.

[0005] To improve the accuracy and reliability of flow field analysis technology and measurement of natural gas flow velocity in LDV / PIV natural gas pipelines, experimental research on the flow field in pressurized natural gas pipelines was conducted. The measurement results were combined with actual flow test data to achieve a more accurate and intuitive study of the flow field within natural gas pipelines. The research results can provide guidance for the efficient operation of natural gas pipeline flow field experimental platforms, offer technical ideas for quality control and uncertainty reduction, provide experimental data and theoretical basis for improving the accuracy of natural gas metering, and also provide fundamental data for the formulation / revision of national, industry, and enterprise standards related to natural gas metering. Existing natural gas flow field testing systems first mix natural gas and tracer particles. After the tracer particles and natural gas are fully mixed, the mixed gas is introduced into the natural gas pipeline for testing.

[0006] Because different particle injection devices have different operating principles and structural requirements, their injection pressure requirements vary. Existing natural gas flow field testing systems all directly inject a mixture of tracer particles and natural gas into the process pipeline via high-pressure gas cylinders. The high-pressure gas cylinders used in various laboratories are primarily nitrogen cylinders, whose small volume limits the injection time. The varying pressure differences result in different injection effects, leading to poor injection efficiency from the particle injection device. This makes it difficult to guarantee that the mixed gas will fully diffuse throughout the natural gas pipeline during injection, resulting in inaccurate flow field test results. Furthermore, the required transparent viewing window differs for flow field analysis of process pipelines with different diameters, and the injection methods of the particle injection devices also vary significantly.

[0007] Therefore, in order to study and analyze the flow field state of different process pipelines and the injection effect of particle injection devices, it is necessary to establish a dual-pipe natural gas flow field testing system and method with adjustable injection pressure. Summary of the Invention

[0008] The technical problem this invention aims to solve is the deteriorating injection effect of particle injection devices in existing natural gas flow field testing systems. This fails to guarantee that the mixed gas can be fully diffused throughout the natural gas pipeline during injection, resulting in poor accuracy of flow field test results. The purpose of this invention is to provide a dual-pipe natural gas flow field testing system and method with adjustable injection pressure. This system can meet the process conditions required by different pipe diameters and particle injection devices, ensuring that the mixed gas can be fully dispersed throughout the test pipeline, thereby improving the accuracy of flow field test results.

[0009] This invention is achieved through the following technical solution:

[0010] In a first aspect, the present invention provides a dual-pipe natural gas flow field testing system with adjustable injection pressure. The system includes a natural gas pressure regulating system, a particle injection system, and a testing pipeline connected sequentially from the natural gas inlet to the outlet direction.

[0011] The natural gas pressure regulating system includes a primary pressure regulating system, a secondary pressure regulating system, and a primary pressure measurement unit, which are connected in series with the test pipeline;

[0012] The particle injection system includes a pressure selection device, a particle injection device, and an injection pipeline. The pressure selection device is used to select a test pipeline with different pressures according to the natural gas pressure regulating system. The particle injection device includes two sets of injection devices with different technical parameters, and the appropriate injection device is selected according to different test pipeline pressures and different test pipeline sizes. The injection pipeline is the connection between the particle injection device and the test pipeline. The injection pipeline is a retractable pipe. Both the pressure selection device and the injection pipeline are equipped with control valves.

[0013] The test pipeline includes process pipeline test sections of different diameters and a non-contact test chamber. The test sections are light-transmitting sections, and the transparent viewing window on the non-contact test chamber is opposite to the test section.

[0014] This invention can meet the filling effect of particle loading devices with different principles and structures, and the mixed gas can be fully dispersed to all parts of the test pipeline. It can be used to conduct test experiments on different process pipelines and improve the accuracy of flow field test results.

[0015] Furthermore, the primary pressure regulating system includes a first pre-control valve, a first pressure regulating valve, and a first post-control valve connected in sequence.

[0016] The input end of the first upstream control valve is connected to upstream natural gas, and the output end of the first downstream control valve is equipped with a first pressure measuring unit; the first pressure measuring unit is used to test the pressure in the pipeline and can be a pressure transmitter for measuring pressure.

[0017] The primary pressure regulating system connects to the secondary pressure regulating system, and the secondary pressure regulating system connects to test pipelines of different diameters;

[0018] The two-stage pressure regulating system includes a second front control valve, a second pressure regulating valve, and a second rear control valve connected in sequence.

[0019] Furthermore, the first front control valve and the first rear control valve are electric valves or pneumatic valves;

[0020] The second front control valve and the second rear control valve are electric valves or pneumatic valves.

[0021] Furthermore, the first pressure measurement unit employs a pressure transmitter.

[0022] Furthermore, the test piping includes a process piping selection unit, test process piping of different diameters, and control valves;

[0023] The process piping selection unit is used to select the process piping required for the experiment based on the experimental needs of different transparent windows.

[0024] The test process pipelines of different diameters include test sections of process pipelines of different diameters and a non-contact test chamber. The test section consists of two different diameter process pipelines and a light-transmitting section. The transparent window on the non-contact test chamber is opposite to the test section. The non-contact test chamber is used to perform particle imaging velocimetry and laser Doppler velocimetry on the test section.

[0025] The control valve can be an electric valve or a pneumatic valve.

[0026] Furthermore, the air intake pipe of the particle injection device is located after the pressure regulation of the primary pressure regulation system and before the pressure regulation of the secondary pressure regulation system to supply air to the particle injection device;

[0027] The intake pipe is buried underground to the test pipeline area, and an interface is reserved near the filling area of ​​the particle filling system, and a local pressure gauge is installed to meet the requirement of simultaneously filling different diameter pipelines with particles.

[0028] The particle injection device does not have high requirements for the stability of the gas source pressure. As long as it can provide a pressure difference range ΔP, it is sufficient and no special pressure stabilization measures are required.

[0029] A suitable diameter pipe section can be used to open a hole and connect a new process pipeline between the primary pressure regulating system and the secondary pressure regulating system to supply gas to the particle injection unit. The inlet of the gas inlet of the particle injection unit is equipped with a control valve to adjust the required natural gas flow according to the particle injection needs, and to facilitate the later maintenance, repair, disassembly and other work of the particle injection unit. A venting pipeline is set on the new pipeline and connected to the existing venting pipeline nearby.

[0030] The above technical solution primarily utilizes a PIV / LDV optical method for natural gas flow testing when conducting natural gas flow field experiments. The effectiveness of particle injection directly impacts the experimental conclusions. During the testing process, tracer particles with a diameter of (5-10) μm or other particle sizes are injected into the natural gas pipeline using a tracer particle injection system. The distribution of tracer particles within the test section of the plexiglass pipeline is then measured using PIV / LDV equipment to reflect the flow field distribution within the pipeline and to conduct related experimental research.

[0031] Based on existing experience with particle injection systems, when conducting flow field tests inside natural gas pipelines, it is necessary to ensure that the pressure difference ΔP between the particle injection device and the natural gas pipeline meets the requirements. Generally, the pressure is approximately 0.2MPa≤ΔP≤2.0MPa. Therefore, it is necessary to calculate the number of particles after screening based on the image processing unit to determine whether the injection effect of the particle injection device meets the technical requirements.

[0032] Secondly, the present invention provides a method for testing the flow field of a dual-pipe natural gas with adjustable injection pressure. This method is based on the aforementioned dual-pipe natural gas flow field testing system with adjustable injection pressure; the method includes:

[0033] Based on the size of different transparent window pipes, select appropriate process pipes and determine the process flow of the test section system;

[0034] Based on the requirements of the natural gas flow field test experiment, the test pressure P0 is determined;

[0035] Based on the injection technology parameters of the particle injection device, determine the pressure difference ΔP of the injection device; after the natural gas flow stabilizes, open the tracer particle injection valve, and obtain the effective particle sampling number N through the image acquisition unit and image processing unit; under optimal conditions, the effective tracer particle sampling number N should be greater than or equal to the preset value (the preset value is 900);

[0036] Based on the test pressure P0, adjust and determine the first pressure P1 and the first valve opening K1 of the first-stage pressure regulating system, and the second pressure P2 and the second valve opening K2 of the second-stage pressure regulating system.

[0037] Based on the pressure difference ΔP of the injection device and the test pressure P0, the pressure control parameters of the natural gas pressure regulating system are determined.

[0038] Further, based on the test pressure P0, the first pressure P1 and the first valve opening K1 of the primary pressure regulating system, and the second pressure P2 and the second valve opening K2 of the secondary pressure regulating system are adjusted and determined, including:

[0039] (1) When ΔP≤P1-P2, the system state remains unchanged, and the states of the first-stage voltage regulation system and the second-stage voltage regulation system remain unchanged;

[0040] (2) When ΔP>P1-P2, after the image processing unit calculates and filters, the effective number of samples N is less than 900, which does not meet the experimental requirements. The first pressure P1 and the first valve opening K1 of the first-stage pressure regulating system are increased, while the second pressure P2 and the second valve opening K2 of the second-stage pressure regulating system are decreased, so that P1-P2≥ΔP.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] This invention discloses a dual-pipe natural gas flow field testing system and method with adjustable injection pressure. The system includes a natural gas pressure regulating system, a particle injection system, and a test pipeline connected sequentially from the natural gas inlet to the outlet. The natural gas pressure regulating system includes a primary pressure regulating system, a secondary pressure regulating system, and a first pressure measurement unit, connected in series with the test pipeline. The particle injection system includes a pressure selection device, a particle injection device, and an injection pipeline. The pressure selection device is used to select test pipelines with different pressures based on the natural gas pressure regulating system. The particle injection device includes two sets of injection devices with different technical parameters, selecting the appropriate injection device based on different test pipeline pressures and sizes. The test pipeline includes a process pipeline selection unit, test process pipelines of different diameters, and control valves. This invention can meet the injection effect requirements of particle injection devices with different principle structures, ensuring that the mixed gas is fully dispersed throughout the test pipeline, allowing for testing experiments on different process pipelines, and improving the accuracy of flow field test results. Attached Figure Description

[0043] 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:

[0044] Figure 1 This is a structural block diagram of a dual-pipe natural gas flow field testing system with adjustable injection pressure according to the present invention;

[0045] Figure 2 This is a schematic diagram of a dual-pipe natural gas flow field testing system with adjustable injection pressure according to the present invention.

[0046] Figure 3 This is a process flow diagram of a dual-pipe natural gas flow field testing system with adjustable injection pressure according to the present invention.

[0047] Figure 4 This is a flowchart of a dual-pipe natural gas flow field testing method with adjustable injection pressure according to the present invention.

[0048] Figure reference numerals and corresponding component names:

[0049] 1-First front control valve, 2-First pressure regulating valve, 3-First rear control valve, 4-First pressure measuring unit, 5-First valve, 6-Second valve, 7-First particle injection device, 8-Second particle injection device, 9-Second front control valve, 10-Second pressure regulating valve, 11-Second rear control valve, 12-First control valve, 13-Second control valve, 14-Second pressure testing unit, 15-Third pressure testing unit. Detailed Implementation

[0050] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of an inventive function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0051] In various embodiments of the invention, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0052] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

[0053] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.

[0054] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0055] 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.

[0056] The extraction, gathering, transportation, and application of natural gas all require flow measurement. Accurate, reliable, fair, and scientific measurement directly affects the legitimate economic interests of both natural gas suppliers and consumers. In recent years, with the implementation and construction of important inter-regional and transnational natural gas transmission pipeline projects, the natural gas market has continued to expand, and trade volume has increased year by year. Only by ensuring accurate natural gas measurement can we provide a scientific basis for the rational use of natural gas and energy conservation and emission reduction, thereby maximizing the economic benefits of natural gas resources.

[0057] Numerous researchers both domestically and internationally have conducted extensive experimental studies on natural gas metering using various flow meters. The results show that many factors influence flow meter performance, particularly the different flow regimes created by varying installation conditions. Most flow meter calculations rely on empirical formulas or mathematical models under ideal flow conditions. However, in practical applications, whether the flow field conditions within the pipe meet the required specifications is crucial for accurate metering.

[0058] Currently, macroscopic experimental studies cannot intuitively and systematically analyze the impact of natural gas flow patterns within pressurized pipelines. Therefore, it is necessary to conduct more comprehensive and in-depth numerical simulations and visualization experiments to verify and quantitatively analyze the flow patterns and structures generated by typical flow obstructions, identify the influence laws on the metering performance of typical flowmeters, and use this information to guide the selection, installation, and use of flowmeters in the field, thereby improving the accuracy of natural gas metering in the field.

[0059] Particle imaging velocimetry (LDV / PIV) is an optical measurement technique that integrates flow visualization and quantitative measurement of flow parameters across the entire flow field. The LDV / PIV system combines the advantages of single-point measurement and display measurement techniques, enabling the measurement of transient velocities across a three-dimensional field with minimal flow field interference and high accuracy and resolution. It can measure not only the flow regime within a pipeline but also the flow velocity in different directions. LDV / PIV can be used for testing gas flow regimes within pipelines and for measuring natural gas flow rates. Its primary application is in understanding the flow field distribution of fluids in natural gas pipelines and accurately measuring the flow velocity at various points within the pipeline. Because velocimetry is traceable to time and length, unlike turbine and ultrasonic flow meters which are traceable to time and mass, LDV / PIV technology is essential for in-depth research into the flow field within pipelines and represents a crucial direction for research and development in the field of metrology.

[0060] To improve the accuracy and reliability of flow field analysis technology and measurement of natural gas flow velocity within LDV / PIV natural gas pipelines, experimental research on the flow field within pressurized natural gas pipelines was conducted. The measurement results were combined with actual flow test data to achieve a more accurate and intuitive study of the flow field within natural gas pipelines. The research findings can provide guidance for the efficient operation of natural gas pipeline flow field experimental platforms, offer technical insights for quality control and uncertainty reduction, provide experimental data and theoretical basis for improving the accuracy of natural gas metering, and also provide fundamental data for the formulation / revision of national, industry, and enterprise standards related to natural gas metering.

[0061] To address the aforementioned issues, this specification provides a structural block diagram and a schematic diagram of the testing method steps for a dual-pipe natural gas flow field testing system with adjustable injection pressure, thereby improving the accuracy of flow field test results.

[0062] This invention can quickly and accurately adjust the tracer particle injection effect according to the technical requirements of different particle injection devices, which is of great significance for improving the technical level of optical measurement of the flow field inside natural gas pipelines.

[0063] Example 1

[0064] like Figure 1 and Figure 2 As shown, the present invention discloses a dual-pipe natural gas flow field testing system with adjustable injection pressure. The system includes a natural gas pressure regulating system, a particle injection system, and a test pipeline connected sequentially from the natural gas inlet to the outlet direction. The natural gas pressure regulating system is also connected to the test pipeline; further see Figure 3.

[0065] The natural gas pressure regulating system includes a primary pressure regulating system, a secondary pressure regulating system, and a first pressure measurement unit 4, which are connected in series with the test pipeline;

[0066] The particle injection system includes a pressure selection device, a particle injection device, and an injection pipeline. The pressure selection device is used to select a test pipeline with different pressures according to the natural gas pressure regulating system. The particle injection device includes two sets of injection devices with different technical parameters, and the appropriate injection device is selected according to the test pipeline with different pressures and different test pipeline sizes. The injection pipeline is the connection between the particle injection device and the test pipeline. The injection pipeline is a retractable pipe. Both the pressure selection device and the injection pipeline are equipped with control valves.

[0067] The test pipeline includes process pipeline test sections of different diameters and a non-contact test chamber. The test sections consist of two different diameter process pipelines and a light-transmitting section. The transparent window on the test chamber is opposite to the test section. The non-contact test chamber is used to perform particle imaging velocimetry and laser Doppler velocimetry on the test sections.

[0068] In this embodiment, the first-stage pressure regulating system includes a first front control valve 1, a first pressure regulating valve 2, and a first rear control valve 3 connected in sequence. The input end of the first front control valve 1 is connected to upstream natural gas, and the output end of the first rear control valve 3 is provided with a first pressure measuring unit 4. The first pressure measuring unit 4 is used to test the pressure in the pipeline and can be a pressure transmitter for measuring pressure. The first front control valve 1 and the first rear control valve 3 can be electric valves or pneumatic valves.

[0069] The primary pressure regulating system is connected to the secondary pressure regulating system through the first manifold, and the secondary pressure regulating system is connected to test pipelines of different diameters through the second manifold. The main function of the first and second manifolds is to buffer the natural gas and ensure the accuracy and stability of pressure regulation.

[0070] The two-stage pressure regulating system includes a second front control valve 9, a second pressure regulating valve 10, and a second rear control valve 11 connected in sequence, wherein the second front control valve 9 and the second rear control valve 11 are electric valves or pneumatic valves.

[0071] In this embodiment, a first valve 5 and a second valve 6 are provided in front of the particle injection device. The first valve 5 is connected to the first particle injection device 7 through a corresponding pressure selection device, and the second valve 6 is connected to the second particle injection device 8 through a corresponding pressure selection device.

[0072] In this embodiment, the test pipeline includes a process pipeline selection unit, test process pipelines of different diameters, and control valves;

[0073] The process piping selection unit is used to select the process piping required for the experiment according to the experimental requirements of different transparent windows. The process piping selection unit includes control valves (first control valve 12 and second control valve 13), wherein the control valves can be electric valves or pneumatic valves, and the process piping required for the experiment can be selected.

[0074] The test process pipelines of different diameters include test sections of process pipelines of different diameters and a non-contact test chamber. The test section consists of two different diameter process pipelines and a light-transmitting section. The transparent window on the non-contact test chamber is opposite to the test section. The non-contact test chamber is used to perform particle imaging velocimetry and laser Doppler velocimetry on the test section.

[0075] The control valves can be electric or pneumatic, and the process piping required for the experiment can be selected.

[0076] In this embodiment, one end of the first control valve 12 is connected to the first particle injection device 7, and the other end is connected to the first pipe in the test pipeline; one end of the first control valve 13 is connected to the second particle injection device 8, and the other end is connected to the second pipe in the test pipeline. Pressure testing units are also respectively installed on different test pipelines to measure the pressure inside the test pipeline. The pressure testing units use pressure transmitters; for example, a second pressure testing unit 14 is installed on the first pipe, and a third pressure testing unit 15 is installed on the second pipe.

[0077] In this embodiment, the required pressure difference ΔP for the stability of natural gas pressure in the particle injection system is: 0.2MPa≤ΔP≤2.0MPa.

[0078] In this embodiment, the air inlet pipe of the particle injection device is located after the pressure regulation of the primary pressure regulation system and before the pressure regulation of the secondary pressure regulation system, so as to supply air to the particle injection device.

[0079] The intake pipe is buried underground to the test pipeline area, and an interface is reserved near the filling area of ​​the particle filling system, and a local pressure gauge is installed to meet the requirement of simultaneously filling different diameter pipelines with particles.

[0080] In this embodiment, a control valve is installed at the inlet of the gas inlet pipe of the particle refueling device to adjust the required natural gas flow rate according to the particle refueling demand, and to facilitate the maintenance, repair, disassembly and other work of the particle refueling device in the future. A venting pipeline is installed on the newly built pipeline and connected to the existing venting pipeline nearby.

[0081] Valves are installed at the connection points between the particle injection device and the natural gas pipeline, except... Figure 3 In addition to the valves already in place, the particle filling device also has valves inside. Control valves are installed on the air inlet pipe connected to the air inlet, the injection pipe connected to the injection port, the air outlet pipe connected to the air outlet and the filling pipe, the air inlet pipe, the injection pipe and the air outlet pipe.

[0082] This invention can meet the filling effect of particle loading devices with different principles and structures, and the mixed gas can be fully dispersed to all parts of the test pipeline. It can be used to conduct test experiments on different process pipelines and improve the accuracy of flow field test results.

[0083] Example 2

[0084] like Figure 4 As shown, the difference between this embodiment and Embodiment 1 is that this embodiment provides a dual-pipe natural gas flow field testing method with adjustable injection pressure. This method is based on the aforementioned dual-pipe natural gas flow field testing system with adjustable injection pressure; the method includes:

[0085] Based on the size of different transparent window pipes, select appropriate process pipes and determine the process flow of the test section system;

[0086] Based on the requirements of the natural gas flow field test experiment, the test pressure P0 is determined;

[0087] Based on the injection technology parameters of the particle injection device, determine the pressure difference ΔP of the injection device; after the natural gas flow stabilizes, open the tracer particle injection valve, and obtain the effective particle sampling number N through the image acquisition unit and image processing unit; under optimal conditions, the effective tracer particle sampling number N should be greater than or equal to 900.

[0088] Based on the test pressure P0, adjust and determine the first pressure P1 and the first valve opening K1 of the first-stage pressure regulating system, and the second pressure P2 and the second valve opening K2 of the second-stage pressure regulating system.

[0089] Based on the pressure difference ΔP of the injection device and the test pressure P0, the pressure control parameters of the natural gas pressure regulating system are determined.

[0090] As a further implementation, based on the test pressure P0, the first pressure P1 and the first valve opening K1 of the primary pressure regulating system, and the second pressure P2 and the second valve opening K2 of the secondary pressure regulating system are adjusted and determined, including:

[0091] (1) When ΔP≤P1-P2, the system state remains unchanged, and the states of the first-stage voltage regulation system and the second-stage voltage regulation system remain unchanged;

[0092] (2) When ΔP>P1-P2, after the image processing unit calculates and filters, the effective number of samples N is less than 900, which does not meet the experimental requirements. The first pressure P1 and the first valve opening K1 of the first-stage pressure regulating system are increased, while the second pressure P2 and the second valve opening K2 of the second-stage pressure regulating system are decreased, so that P1-P2≥ΔP.

[0093] This invention, based on the above-described method for testing the flow field of dual-pipe natural gas with adjustable injection pressure, determines pressure control parameters to achieve dual-pipe natural gas flow field testing. This invention can meet the injection effect requirements of particle loading devices with different principle structures, ensuring the mixed gas is fully dispersed throughout the test pipeline. It allows for testing experiments on different process pipelines, improving the accuracy of flow field test results.

[0094] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual pipe natural gas flow field test system with adjustable fill pressure, characterized in that, The system comprises, in sequence from the natural gas inlet to the outlet, a natural gas pressure regulating system, a particle injection system and a test pipeline; The natural gas pressure regulating system comprises a first-stage pressure regulating system, a second-stage pressure regulating system and a first pressure measuring unit, which are connected in series with the test pipeline; The particle injection system comprises a pressure selection device, a particle injection device and an injection pipeline, wherein the pressure selection device is used to select the test pipeline with different pressures according to the natural gas pressure regulating system; the particle injection device comprises two sets of injection devices with different technical parameters, and the corresponding injection device is selected according to the pressure and size of the test pipeline; and the injection pipeline is a connecting piece of the particle injection device and the test pipeline. The test pipeline comprises test pipeline sections with different diameters and a non-contact test cabin, the test section is a light-transmitting section, and a transparent window on the non-contact test cabin is opposite to the test section.

2. The dual pipe natural gas flow field test system with adjustable filling pressure according to claim 1, characterized in that, The first-stage pressure regulating system comprises a first front control valve, a first pressure regulating valve and a first rear control valve connected in sequence, the input end of the first front control valve is connected to the upstream natural gas, and the output end of the first rear control valve is provided with a first pressure measuring unit; and the first pressure measuring unit is used to test the pressure in the test pipeline. The first-stage pressure regulating system is connected to the second-stage pressure regulating system, and the second-stage pressure regulating system is connected to the test pipeline with different diameters. The second-stage pressure regulating system comprises a second front control valve, a second pressure regulating valve and a second rear control valve connected in sequence.

3. The dual-tube natural gas flow field test system with adjustable filling pressure according to claim 2, characterized in that, The first front control valve and the first rear control valve are electric valves or pneumatic valves. The second front control valve and the second rear control valve are electric valves or pneumatic valves.

4. The dual-tube natural gas flow field test system with adjustable filling pressure according to claim 2, characterized in that, The first pressure measuring unit adopts a pressure transmitter.

5. The dual pipe natural gas flow field test system with adjustable filling pressure according to claim 1, characterized in that, The test pipeline comprises a process pipeline selection unit, test process pipelines with different diameters and control valves. The process pipeline selection unit is used to select the required process pipeline according to the experimental requirements of different transparent windows. The test process pipelines with different diameters comprise test pipeline sections with different diameters and a non-contact test cabin, the test section is composed of two process pipelines with different diameters and a light-transmitting section; and the transparent window on the non-contact test cabin is opposite to the test section, and the non-contact test cabin is used to perform particle imaging velocimetry and laser Doppler velocimetry on the test section.

6. The dual pipe natural gas flow field test system with adjustable filling pressure according to claim 1, characterized in that, The pressure difference ΔP required by the particle injection system for the stability of the natural gas pressure is 0.2 MPa≤ΔP≤2.0 MPa.

7. The dual-tube natural gas flow field test system with adjustable filling pressure according to claim 1, characterized in that, The gas inlet pipeline of the particle injection device is arranged after the pressure regulation of the first-stage pressure regulating system and before the pressure regulation of the second-stage pressure regulating system, and supplies gas to the particle injection device. The gas inlet pipeline is buried and laid to the test pipeline area, an interface is reserved near the injection area of the particle injection system, an in-situ pressure gauge is arranged, and the requirements of simultaneously injecting particles into pipelines with different diameters are met.

8. The dual-tube natural gas flow field test system with adjustable filling pressure according to claim 7, characterized in that, A control valve is arranged at the inlet of the gas inlet pipeline of the particle injection device, which is used to adjust the required natural gas flow according to the particle injection requirements, and is also used for the maintenance, repair and disassembly of the particle injection device in the later stage.

9. A method of testing a dual pipe natural gas flow field with adjustable fill pressure, the method comprising: The method is based on a double-pipeline natural gas flow field test system with adjustable injection pressure as claimed in any one of claims 1 to 8; and the method comprises: According to the size of different transparent window pipes, corresponding process pipes are selected to determine the process flow of the test section system; According to the natural gas flow field test experiment requirements, the test experiment pressure P0 is determined; According to the injection technical parameters of the particle injection device, the pressure difference ΔP of the injection device is determined; when the natural gas flow state is stable, the tracer particle injection valve is opened, the effective particle sampling number N is obtained through the image acquisition unit and the image processing unit; the effective particle sampling number N under the optimal state is greater than or equal to the preset value; According to the test experiment pressure P0, the first pressure P1 and the first valve opening K1 of the primary pressure regulating system, and the second pressure P2 and the second valve opening K2 of the secondary pressure regulating system are adjusted and determined; According to the pressure difference ΔP of the injection device and the test experiment pressure P0, the pressure control index of the natural gas pressure regulating system is determined.

10. The method of claim 9, wherein the method is a dual-tube natural gas flow field test method with adjustable filling pressure, characterized in that, According to the test experiment pressure P0, the first pressure P1 and the first valve opening K1 of the primary pressure regulating system, and the second pressure P2 and the second valve opening K2 of the secondary pressure regulating system are adjusted and determined, including: When ΔP≤P1-P2, the system state is kept unchanged, and the primary pressure regulating system and the secondary pressure regulating system are kept unchanged; When ΔP>P1-P2, after calculation and screening through the image processing unit, the effective sampling number N is less than the preset value, which does not meet the experimental requirements, the first pressure P1 and the first valve opening K1 of the primary pressure regulating system are increased, and the second pressure P2 and the second valve opening K2 of the secondary pressure regulating system are decreased, so that P1-P2≥ΔP.

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