High-pressure and multi-steel-grade natural gas pipeline multi-stage hydrogen doping device and method

Abstract

The invention discloses a multi-stage hydrogen doping device and method for a high-pressure and multi-steel-stage natural gas pipeline. The multi-stage hydrogen doping device comprises a hydrogen source system, a natural gas source system, a static mixer and a test pipeline system, the natural gas source system is connected with the hydrogen source system, the hydrogen source system is connected with an inlet of the static mixer, the natural gas source system is connected with the static mixer and the test pipeline system in parallel, the natural gas source system is connected with the inlet of the static mixer, the test pipeline system is connected with an outlet of the static mixer, and the static mixer is connected with the test pipeline system. And a hydrogen compressor is arranged on a hydrogen pipeline between the hydrogen source system and the inlet of the static mixer. The high-pressure, large-flow and multi-hydrogen-doping-ratio in-service natural gas pipeline hydrogen doping test can be achieved, meanwhile, a high-hydrogen-doping-ratio in-station experiment and low-hydrogen-doping-ratio industrial output are conducted, hydrogen is doped into a natural gas pipeline network on a large scale, and various industrial and civil requirements are met.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen blending technology for natural gas pipelines, and in particular, it relates to a multi-stage hydrogen blending device and method for high-pressure, multi-grade natural gas pipelines. Background Technology

[0002] Hydrogen energy is a green, low-carbon, and widely applicable secondary energy source, playing a crucial role in building a clean, low-carbon, safe, and efficient energy system. Blending hydrogen into natural gas pipelines for transportation is currently recognized as one of the main pathways for hydrogen energy utilization. This blending enables large-scale, low-cost, and long-distance hydrogen transportation, while also addressing issues such as the instability of photovoltaic and wind power, the difficulty of hydrogen storage and transportation, and the waste of natural gas infrastructure, thus contributing to the efficient utilization of new energy sources. Research on hydrogen-blended natural gas pipelines is still in its early stages. The adaptability of natural gas pipeline networks after blending, the impact of hydrogen embrittlement on pipe materials, and the optimal blending ratio remain inconclusive. There is an urgent need to establish an industrial platform to verify the feasibility of blending hydrogen into in-service pipelines.

[0003] The invention patent, "A Multi-Stage Pressure Natural Gas Pipeline Hydrogen Blending Experimental System for Medium and Low Pressure," can complete hydrogen blending under medium and low pressure conditions and conduct hydrogen blending experiments under different pressure conditions through pressure regulation. However, it is difficult to conduct hydrogen blending experiments under high pressure and is limited to variable pressure tests. Its single function does not meet the needs of industrial hydrogen blending experiments.

[0004] The invention patent "A Natural Gas Hydrogen Blending Experimental System and Its Control Method" achieves simultaneous hydrogen blending experiments with two blending ratios by starting and stopping two blending devices. This method essentially achieves two streams of hydrogen through two hydrogen blending devices in parallel, with each stage being independent of the others, making it difficult to perform unified verification.

[0005] The invention patent "A Comprehensive Experimental System for Hydrogen Blending in Natural Gas Pipelines" enables simultaneous hydrogen blending experiments in natural gas pipelines under multiple pressure conditions by setting up five pipeline branches with different pressure levels. This method achieves pressure regulation through the pre-set five pipeline branches, but the pressure regulation range is limited and the process is complex.

[0006] In summary, existing hydrogen blending systems for natural gas pipelines are mostly in the laboratory and pilot-scale stages, with low pressure ratings and limited pressure regulation ranges, making it difficult to meet the high-pressure hydrogen blending requirements of in-service pipelines. Existing test equipment has low throughput, small pipe diameters, and uses a single type of steel, making it difficult to support hydrogen blending transportation in large-diameter, high-throughput in-service pipelines based on test results. Furthermore, there are currently no industrial application examples for existing equipment, and the adaptability of small-scale tests to industrial hydrogen blending cannot be guaranteed. In verifying the hydrogen blending adaptability of pipe materials and pipeline fittings, it remains unclear whether newly built equipment can be benchmarked against in-service pipe materials and pipeline fittings. Summary of the Invention

[0007] The purpose of this invention is to provide a high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device and method to solve the problems of low pressure and small throughput in existing hydrogen blending test systems.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device includes a hydrogen source system, a natural gas source system, a static mixer, and a test pipeline system;

[0010] The natural gas source system is connected to the hydrogen source system, the hydrogen source system is connected to the inlet of the static mixer, the natural gas source system is connected in parallel with the static mixer and the test pipeline system, the natural gas source system is connected to the inlet of the static mixer, the test pipeline system is connected to the outlet of the static mixer, and a hydrogen compressor is installed on the hydrogen pipeline between the hydrogen source system and the inlet of the static mixer.

[0011] Furthermore, the test pipeline system includes a crude hydrogen test pipeline and several high-pressure hydrogen doping test pipelines, wherein the crude hydrogen test pipeline includes a low-pressure crude hydrogen test pipeline and a high-pressure crude hydrogen test pipeline.

[0012] Furthermore, the low-pressure crude hydrogen test pipeline is installed on the hydrogen pipeline between the hydrogen source system and the hydrogen compressor, and the high-pressure crude hydrogen test pipeline is installed on the hydrogen pipeline between the hydrogen compressor and the inlet of the static mixer.

[0013] Furthermore, a hydrogen flow regulating valve and a mass flow meter are sequentially installed on the hydrogen pipeline between the hydrogen source system and the low-pressure crude hydrogen test pipeline.

[0014] Furthermore, the high-pressure hydrogen-blending test pipeline is installed between the outlet of the static mixer and the mixed gas pipeline.

[0015] Furthermore, the high-pressure hydrogen-doping test pipeline includes a high-steel-grade test pipeline, a low-steel-grade test pipeline, and pipeline fittings.

[0016] Furthermore, the pipeline fittings include flanges, valves, and flow meters.

[0017] Furthermore, the natural gas source system includes several natural gas pipelines, and a natural gas flow regulating valve and a mass flow meter are sequentially installed between the natural gas pipelines and the inlet of the static mixer.

[0018] Furthermore, several of the aforementioned natural gas pipelines are connected to hydrogen pipelines.

[0019] A method for multi-stage hydrogen blending in a high-pressure, multi-grade natural gas pipeline using the aforementioned apparatus, comprising:

[0020] Determine the required hydrogen source flow rate, external hydrogen blending pressure, and external hydrogen blending ratio for the hydrogen blending test;

[0021] The hydrogen doping ratio for each stage of the hydrogen doping test is determined based on the hydrogen source output, the external hydrogen doping pressure, and the external hydrogen doping ratio requirements.

[0022] Control the pipeline fittings on each natural gas pipeline and hydrogen pipeline, and adjust the static mixer to mix each gas at a determined hydrogen blending ratio at each stage;

[0023] Each stage of the blended gas undergoes an adaptability test through a high-pressure hydrogen blending test pipeline, and the final stage of blended gas is transported out through a mixed gas pipeline.

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

[0025] This invention provides a high-pressure, multi-grade, multi-stage hydrogen blending device for natural gas pipelines. By connecting the natural gas source system to a hydrogen source system, and the hydrogen source system to the inlet of a static mixer, and installing a hydrogen compressor on the hydrogen pipeline, the natural gas source system, static mixer, and test pipeline system are connected in parallel to achieve multi-stage blending of natural gas and hydrogen. This invention proposes a high-pressure, multi-grade, high-flow-rate multi-stage hydrogen blending process experimental device based on in-service natural gas pipelines. It can realize hydrogen blending tests on in-service natural gas pipelines with high pressure, high flow rate, and multiple hydrogen blending ratios, and study the hydrogen blending adaptability of pipe materials and pipeline fittings. Simultaneously, it conducts high-hydrogen-ratio in-station experiments and low-hydrogen-ratio industrial external transmission, realizing large-scale hydrogen blending into the natural gas pipeline network. Through precise control, different hydrogen blending ratios can be achieved. By accurately controlling the hydrogen blending ratio and transmission performance, this device can meet the needs of different industries and users, satisfying various industrial and civil requirements. It provides strong support for the promotion and application of natural gas hydrogen blending technology.

[0026] Furthermore, this invention includes a hydrogen compressor installed on the hydrogen pipeline between the hydrogen source system and the inlet of the static mixer. This compressor pressurizes the hydrogen output from the hydrogen source system to the required pressure. The hydrogen compressor has high compression efficiency and stability, and can meet the requirements of different mixing pressures and flow rates. Simultaneously, the pressurization range of the hydrogen compressor can be adjusted according to user and experimental needs.

[0027] Furthermore, the present invention sets up multiple monitoring points and control instruments between the hydrogen source system, the natural gas source system, the hydrogen compressor, the static mixer, and the test pipeline system. These monitoring points and control instruments can monitor and record the operating status of the device in real time, such as parameters like pressure, flow rate, and temperature, and make precise adjustments through the automatic control system to meet the requirements of blending and transportation. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device of the present invention.

[0030] Figure 2 This is a schematic diagram of the multi-stage hydrogen blending device for high-pressure, multi-steel-grade natural gas pipelines according to Embodiment 1 of the present invention.

[0031] Figure 3 This is a flowchart of the multi-stage hydrogen blending method for high-pressure, multi-grade natural gas pipelines according to the present invention.

[0032] Among them: 1-low-pressure crude hydrogen test pipeline, 2-hydrogen compressor, 3-high-pressure crude hydrogen test pipeline, 4-static mixer, 5-high-pressure hydrogen blending test pipeline. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] See Figure 1This invention provides a high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device, including a hydrogen source system, a natural gas source system, a hydrogen compressor 2, a static mixer 4, and a test pipeline system. The hydrogen source system is one of the core components of this device, providing a stable hydrogen source, which can be either test hydrogen or industrial-grade high-flow-rate crude hydrogen. The pressurization range of the hydrogen compressor 2 can be determined according to user and test requirements. The hydrogen source system is connected to the inlet of the static mixer 4. The hydrogen compressor 2 is installed on the hydrogen pipeline between the hydrogen source system and the inlet of the static mixer 4. The hydrogen compressor 2 pressurizes the hydrogen from the hydrogen source system to the required pressure to meet the requirements of subsequent blending and transportation. Simultaneously, the pressurization range of the hydrogen compressor 2 can be adjusted according to user and test requirements. The natural gas source system provides a stable natural gas source, forming the basis for blending together with the hydrogen source system. A natural gas source system, static blender 4, and test pipeline system are connected in parallel with multiple branches to achieve multi-stage hydrogen blending. The natural gas source system is connected to the inlet of static blender 4, and the test pipeline system is connected to the outlet of static blender 4. Static blender 4 is a key component for achieving hydrogen-natural gas blending. It employs advanced static mixing technology, enabling thorough mixing of hydrogen and natural gas in a short time, allowing the blended gas to enter subsequent processing stages through the test pipeline system. The natural gas source system includes several natural gas pipelines, all of which are connected to hydrogen pipelines. A natural gas flow regulating valve and a mass flow meter are sequentially installed between the natural gas pipelines and the inlet of static blender 4. The test pipeline system includes a crude hydrogen test pipeline and several high-pressure hydrogen blending test pipelines 5. The crude hydrogen test pipelines include a low-pressure crude hydrogen test pipeline 1 and a high-pressure crude hydrogen test pipeline 3. The low-pressure crude hydrogen test pipeline 1 is installed on the hydrogen pipeline between the hydrogen source system and the hydrogen compressor 2. A hydrogen flow regulating valve and a mass flow meter are sequentially installed on the hydrogen pipeline between the hydrogen source system and the low-pressure crude hydrogen test pipeline 1. The high-pressure crude hydrogen test pipeline 3 is installed on the hydrogen pipeline between the hydrogen compressor 2 and the inlet of the static mixer 4. The high-pressure hydrogen blending test pipeline 5 is installed between the outlet of the static mixer 4 and the mixed gas pipeline. The high-pressure hydrogen blending test pipeline 5 includes high-grade steel test pipelines, low-grade steel test pipelines, and pipeline fittings, including flanges, valves, and flow meters. The materials, specifications, and service life of these pipelines and fittings are selected and adjusted according to actual needs. After passing through the test pipeline system and the device test system, natural gas and hydrogen, after passing through the static mixer 4, are connected to the end-user system as a product via the mixed gas pipeline. The hydrogen blending ratio of the multi-stage blended gas can be adjusted according to the needs of the user system to meet the conditions for input into the user system, and is then connected to the end-user system as an external product.

[0041] Both high-grade and low-grade test pipelines include pipes of different service times, steel grades, and sizes, including but not limited to L245N, L245NS, X80, X65, and X50 steel grades. Pipeline fittings for the test pipeline system include fittings of different service times, types, and sizes, including but not limited to flanges, valves of different specifications, and flow meters of different specifications. Multiple ball valves, flanges, shut-off valves, and supporting monitoring instruments are installed between the hydrogen source system, natural gas source system, hydrogen compressor 2, static mixer 4, and the test pipeline system. These monitoring points and control instruments can monitor and record the operating status of the device in real time, such as pressure, flow rate, and temperature parameters, and through automatic control, precisely control the flow rate and blending ratio of natural gas and hydrogen to ensure the safe and stable operation of the device.

[0042] This embodiment enables the implementation of hydrogen blending processes with high flow rates and multiple hydrogen blending ratios under high pressure operation. While conducting research on the adaptability of pipe materials and pipeline accessories for hydrogen blending, it also meets the needs of industrial mixed gas export, realizing the research on high hydrogen blending ratios for primary and secondary stages and the export of low hydrogen blending ratios for tertiary stages.

[0043] This invention also provides a multi-stage hydrogen blending method for high-pressure, multi-grade natural gas pipelines, specifically including the following steps:

[0044] S1: Based on the actual application scenario or user needs, specify the specific parameters for the hydrogen coagulation test. These parameters include the hydrogen source output, external hydrogen coagulation pressure, and external hydrogen coagulation ratio requirements corresponding to the hydrogen coagulation test.

[0045] S2: After determining the specific parameters of the hydrogen blending test, the hydrogen blending ratio of natural gas at each stage is further calculated and determined based on the hydrogen source flow rate, external hydrogen blending pressure, and external hydrogen blending ratio requirements. Due to the differences in the physical and chemical properties of natural gas and hydrogen, precise blending is required under different pressure and flow conditions. Through precise calculations and simulations, the optimal ratio of natural gas to hydrogen in each blending stage can be determined to ensure the quality and stability of the mixed gas.

[0046] S3: Based on the calculated hydrogen blending ratios at each stage, the static mixer 4 is adjusted by precisely controlling the pipeline fittings on each natural gas pipeline and hydrogen pipeline to blend the gases at the determined hydrogen blending ratios at each stage.

[0047] S4: After blending, the gases at each stage of blending undergo adaptability tests through high-pressure hydrogen-blending test pipelines. These test pipelines include pipes and fittings of different steel grades and sizes, simulating the gas transport process in a real pipeline environment. Through these adaptability tests, the transport performance and stability of the blended gases can be evaluated, ensuring that the mixed gas meets the requirements of the user's system. The final stage of blended gas is then transported out through the mixed gas pipeline to the user's system for use.

[0048] Example 1:

[0049] like Figure 2 As shown, the high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device provided in this embodiment includes a hydrogen source system, a natural gas source system, a hydrogen compressor 2, a static mixer 4, and a test pipeline system. The hydrogen source system provides experimental hydrogen. The test pipeline system includes: a crude hydrogen test pipeline, a first hydrogen blending ratio test pipeline, a second hydrogen blending ratio test pipeline, a third hydrogen blending ratio test pipeline, and corresponding flow meters, valves, and related fittings of various types. The hydrogen source system is pressurized by the hydrogen compressor 2 after passing through the crude hydrogen test pipeline and connected to the inlet of the static mixer 4. The natural gas source system includes: a first natural gas source, a second natural gas source, and a third natural gas source, along with corresponding flow meters and valves. The three natural gas sources are connected in parallel with the static mixer 4 and the test pipeline system to achieve multi-stage hydrogen blending. The first natural gas source in the natural gas supply system is connected to a hydrogen source after being pressurized by hydrogen compressor 2, achieving primary hydrogen blending. The mixed gas after primary blending is connected to the first hydrogen blending ratio test pipeline to conduct adaptability tests on high-grade and low-grade test pipelines and pipeline fittings with different service times under the primary hydrogen blending ratio. The second natural gas source in the natural gas supply system is directly connected to the inlet of static mixer 4, achieving secondary hydrogen blending with the mixed gas after primary blending. The mixed gas after secondary blending is connected to the second hydrogen blending ratio test pipeline to conduct adaptability tests on high-grade and low-grade test pipelines and pipeline fittings with different service times under the secondary hydrogen blending ratio. The first and second hydrogen blending ratio test pipelines in the test pipeline system are respectively connected to the outlet of static mixer 4. After passing through the static mixer 4, the natural gas and hydrogen pass through the test pipeline system and are connected to the third natural gas source in the natural gas supply system to achieve tertiary hydrogen blending. The mixed gas after tertiary blending meets the conditions for input into the user system and is connected to the end-user system as an external output product.

[0050] Example 2:

[0051] The difference from Example 1 is that the hydrogen source system is industrial-grade crude hydrogen with a large flow rate.

[0052] Example 3:

[0053] like Figure 3 As shown, this embodiment illustrates the hydrogen doping method of Examples 1 and 2, specifically including the following steps:

[0054] S1: First, it is necessary to determine the hydrogen source output, i.e., the amount of hydrogen supplied per hour or per minute. Simultaneously, based on the user system's requirements and the actual application scenario, determine the required external hydrogen blending pressure and blending ratio.

[0055] S2: Based on the hydrogen source output, external hydrogen blending pressure, and external hydrogen blending ratio requirements, calculate and determine the three-stage hydrogen blending ratio of natural gas in the hydrogen blending test, clarify the test time and test plan information, and ensure the orderly conduct of the test process.

[0056] S3: During the blending process, it is necessary to precisely control the pipeline fittings on each natural gas pipeline and hydrogen pipeline, and adjust the static blender 4 to blend each gas at a determined three-stage hydrogen blending ratio. By adjusting the state of the pipeline fittings, the flow rate and pressure of natural gas and hydrogen are controlled to achieve the blending of the two gases at a determined three-stage hydrogen blending ratio.

[0057] S4: After blending, the three-stage blended gases undergo adaptability tests through a three-stage high-pressure hydrogen blending ratio test pipeline. These test pipelines simulate the gas transport process under real pipeline conditions to evaluate the transport performance and stability of the blended gases, ensuring that the mixed gas meets the user's system requirements. Finally, the third-stage blended gas, after metering, is transported out through the mixed gas pipeline to the user's system.

[0058] This invention achieves highly efficient blending of natural gas and hydrogen through precise control and multi-stage hydrogen blending ratio settings. This method not only ensures the quality and stability of the mixed gas but also meets the specific needs of user systems. Furthermore, through adaptability testing and metering control, the delivery performance and safety of the mixed gas are further improved.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 high-pressure, multi-grade, multi-stage hydrogen blending device for natural gas pipelines, characterized in that, This includes a hydrogen source system, a natural gas source system, a static mixer, and a test pipeline system; The natural gas source system is connected to the hydrogen source system, the hydrogen source system is connected to the inlet of the static mixer, the natural gas source system is connected in parallel with the static mixer and the test pipeline system, the natural gas source system is connected to the inlet of the static mixer, the test pipeline system is connected to the outlet of the static mixer, and a hydrogen compressor is installed on the hydrogen pipeline between the hydrogen source system and the inlet of the static mixer.

2. The high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 1, characterized in that, The test pipeline system includes a crude hydrogen test pipeline and several high-pressure hydrogen doping test pipelines. The crude hydrogen test pipeline includes a low-pressure crude hydrogen test pipeline and a high-pressure crude hydrogen test pipeline.

3. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 2, characterized in that, The low-pressure crude hydrogen test pipeline is installed on the hydrogen pipeline between the hydrogen source system and the hydrogen compressor, and the high-pressure crude hydrogen test pipeline is installed on the hydrogen pipeline between the hydrogen compressor and the inlet of the static mixer.

4. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 3, characterized in that, A hydrogen flow regulating valve and a mass flow meter are sequentially installed on the hydrogen pipeline between the hydrogen source system and the low-pressure crude hydrogen test pipeline.

5. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 2, characterized in that, The high-pressure hydrogen-blending test pipeline is installed between the outlet of the static mixer and the mixed gas pipeline.

6. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 2 or 5, characterized in that, The high-pressure hydrogen-doping test pipeline includes high-grade steel test pipeline, low-grade steel test pipeline, and pipeline fittings.

7. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 6, characterized in that, The pipeline fittings include flanges, valves, and flow meters.

8. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 1, characterized in that, The natural gas source system includes several natural gas pipelines, and a natural gas flow regulating valve and a mass flow meter are sequentially installed between the natural gas pipelines and the inlet of the static mixer.

9. A high-pressure, multi-grade natural gas pipeline multi-stage hydrogen blending device according to claim 8, characterized in that, Several of the natural gas pipelines are connected to hydrogen pipelines.

10. A method for multi-stage hydrogen blending in high-pressure, multi-grade natural gas pipelines using the apparatus described in any one of claims 1 to 9, characterized in that, include: Determine the required hydrogen source flow rate, external hydrogen blending pressure, and external hydrogen blending ratio for the hydrogen blending test; The hydrogen doping ratio for each stage of the hydrogen doping test is determined based on the hydrogen source output, the external hydrogen doping pressure, and the external hydrogen doping ratio requirements. Control the pipeline fittings on each natural gas pipeline and hydrogen pipeline, and adjust the static mixer to mix each gas at a determined hydrogen blending ratio at each stage; Each stage of the blended gas undergoes an adaptability test through a high-pressure hydrogen blending test pipeline, and the final stage of blended gas is transported out through a mixed gas pipeline.

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