Tangential branch of hydrogen-doped natural gas pipeline and performance evaluation method

Abstract

The application provides a tangential branch of a hydrogen-doped natural gas pipeline and a performance evaluation method, relates to the hydrogen-doping technical field of a natural gas pipeline, and the tangential branch comprises a main pipe, a branch pipe, a front flange, a rear flange, a main pipe gas inlet, a branch pipe gas inlet, a gas outlet and a flow field monitoring module. The device and the method realize an integrated process from design, simulation to manufacturing and verification of the hydrogen-doped natural gas pipeline, and significantly improve the mixing uniformity and the conveying safety.

Description

Technical Field

[0001] This invention relates to the field of hydrogen blending technology for natural gas pipelines, and more particularly to a tangential branch pipe of a hydrogen-blended natural gas pipeline and a method for evaluating its performance. Background Technology

[0002] Hydrogen, due to its non-carbonizing and renewable properties, possesses inherent advantages and broad application prospects in future energy applications. However, hydrogen transportation efficiency is currently a bottleneck restricting the development of the hydrogen energy industry. Some have proposed transporting hydrogen through existing natural gas pipelines to reduce transportation costs, but the density difference between hydrogen and methane causes stratification of the mixed gas within the pipeline. This uneven distribution leads to excessively high hydrogen partial pressure in localized areas, potentially causing pipeline failure and leakage risks, posing a significant challenge to gas transportation. Summary of the Invention

[0003] Based on the above-mentioned technical problems, traditional hydrogen-blended natural gas pipelines have a simple structure and the natural gas and hydrogen cannot be effectively mixed inside the pipeline, which easily leads to hydrogen embrittlement. Therefore, this paper provides equipment and performance evaluation methods for hydrogen-blended natural gas pipelines.

[0004] The technical means employed in this invention are as follows: A tangential branch pipe for a hydrogen-blended natural gas pipeline, suitable for a natural gas hydrogen-blended transportation pipeline system, comprising: Main pipe, branch pipe, front flange, rear flange, main pipe inlet, branch pipe inlet, outlet, and flow field monitoring module; The main pipe has an air inlet and an air outlet at its two ends, respectively; there is at least one branch pipe; the branch pipe is tangentially connected to the outer diameter of the main pipe and is used for hydrogen injection; the front flange and the rear flange are used for sealing the pipe section; the flow field monitoring module is used to detect the gas velocity and concentration distribution in the mixing area.

[0005] Furthermore, the branch pipe is a single branch pipe, a double branch pipe, or multiple branch pipes that are tangentially arranged to the main pipe.

[0006] Furthermore, the angle between the branch pipe and the main pipe axis is... The angle between the airflow direction in the branch pipe and the direction of gravity is... .

[0007] Furthermore, when the branch pipe is a double branch pipe; if the double branch pipe is a symmetrical double branch pipe tangentially arranged with the main pipe, the two branch pipes are mirror-symmetric about a plane passing through the axis of the main pipe; if the double branch pipe is an asymmetrical double branch pipe tangentially arranged with the main pipe, the two branch pipes are centrally symmetric about the axis of the main pipe.

[0008] Furthermore, the branch pipe is connected to the main pipe via a flange or a threaded connection.

[0009] Furthermore, the gas entering through the main pipe is natural gas; the gas entering through the branch pipe is hydrogen.

[0010] This invention also includes a method for evaluating the performance of tangential branch pipes in a hydrogen-blended natural gas pipeline, comprising the following steps: S1. Establish the geometric model of the main pipe and branch pipes, and define the ratio of the hydrogen gas position to the diameter at the inlet. Angle and included angle ; S2. CFD numerical simulation was used to calculate the flow field distribution of hydrogen and natural gas at different angles; S3. Introduce COV to assess the degree of mixing of the two gases in the pipeline; according to industry standards, when COV < 5%, the mixing is generally considered sufficient. S4. Manufacture the tangential branch pipe assembly according to the optimized parameters and conduct a uniformity test on the experimental platform. S5. Adjust the design parameters based on the experimental feedback results to achieve closed-loop optimization of the method.

[0011] Furthermore, the formula for calculating COV is: ; in, This represents the hydrogen mole fraction at each point on a given cross-section. This represents the arithmetic mean of the hydrogen mole fractions on the selected cross section; This represents the total number of points sampled from the cross section.

[0012] Compared with the prior art, the present invention has the following advantages: The device and method of this invention realize an integrated process from design, simulation to manufacturing and verification of hydrogen-blended natural gas pipelines, which significantly improves the mixing uniformity and transportation safety. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the single tangential branch rotating flange of the present invention.

[0015] Figure 2 This is a schematic diagram of a single tangential branch pipe according to the present invention.

[0016] Figure 3This is a schematic diagram of the tangential pipe structure of the present invention.

[0017] Figure 4 The angle between the airflow direction of the branch pipe and the direction of gravity in this invention is given.

[0018] Figure 5 The present invention is a symmetrical double-branch pipe .

[0019] Figure 6 It is a special angle branch pipe for conventional hydrogen doping.

[0020] Figure 7 This is a schematic diagram of the asymmetric tangential double-branch structure of the present invention.

[0021] Figure 8 This is a left view of the asymmetric tangential double-branch pipe of the present invention.

[0022] In the diagram, 1 is the main pipe; 2 is the branch pipe; 3 is the front flange; 4 is the rear flange; 5 is the main pipe inlet; 6 is the branch pipe inlet; 7 is the outlet; and 8 is the flow field detection module. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] like Figure 1-8As shown, this invention provides a tangential branch pipe for a hydrogen-blended natural gas pipeline, comprising: a main pipe, a branch pipe, a methane inlet, a hydrogen inlet, an outlet, a front flange, and a rear flange. The branch pipe of this invention differs from a conventional T-type hydrogen-blended pipeline in that, in a conventional T-type hydrogen-blended pipeline, the axis of the branch pipe section is perpendicular to the axis of the main pipe section and is inserted into the main pipe section from bottom to top. In this invention, the outer diameter of the branch pipe section is tangential to the outer diameter of the main pipe section and is inserted into the main pipe section at a special angle (e.g., ...). Figure 2 To better understand this angle, the following explanation is provided: Figure 2 This is a schematic diagram of a single tangential branch pipe, where the main pipe inlet is a methane inlet, the branch pipe inlet is a hydrogen inlet, and the outlet is a mixed gas outlet. The angle between the axes of the main pipe and the branch pipe is [angle missing]. The angle between the airflow direction in the branch pipe and the direction of gravity is... .like Figure 3 A schematic diagram showing the angle between the branch pipe and the main pipe axis is provided, such as... Figure 4 A schematic diagram showing the angle between the airflow direction in the branch pipe and the direction of gravity is displayed.

[0026] like Figure 1 As shown, a tangential branch pipe of a hydrogen-blended natural gas pipeline, suitable for a natural gas hydrogen-blended transportation pipeline system, includes: a main pipe 1, a branch pipe 2, a front flange 3, a rear flange 4, a main pipe inlet 5, a branch pipe inlet 6, an outlet 7, and a flow field monitoring module 8. The two ends of the main pipe 1 are the main pipe inlet 5 and the outlet 7, respectively; there is at least one branch pipe 2; the branch pipe 2 is tangentially connected to the outer diameter of the main pipe 1 and used for hydrogen injection; the front flange 3 and the rear flange 4 are used for sealing the pipe section; the flow field monitoring module 8 is used to detect the gas velocity and concentration distribution in the mixing area.

[0027] In a preferred embodiment, in this application, the branch pipe 2 is a single branch pipe, a double branch pipe, or multiple branch pipes that are tangential to the main pipe 1.

[0028] The angle between the branch pipe 2 and the main pipe axis is: The angle between the airflow direction in the branch pipe and the direction of gravity is... When the branch pipe 2 is a double branch pipe; if the double branch pipe is a symmetrical double branch pipe tangentially arranged with the main pipe, the two branch pipes are mirror-symmetrical about a plane passing through the axis of the main pipe; if the double branch pipe is an asymmetrical double branch pipe tangentially arranged with the main pipe, the two branch pipes are centrally symmetrical about the axis of the main pipe. The branch pipe 2 is connected to the main pipe 1 by a flange or a threaded connection.

[0029] In this application, the gas entering the main pipe 1 is natural gas; the gas entering the branch pipe 2 is hydrogen.

[0030] This invention also provides a method for evaluating the performance of tangential branch pipes in hydrogen-blended natural gas pipelines, comprising the following steps: S1. Establish the geometric model of the main pipe and branch pipes, and define the ratio of the hydrogen gas position to the diameter at the inlet. Angle and included angle ; S2. CFD numerical simulation was used to calculate the flow field distribution of hydrogen and natural gas at different angles; S3. COV (Coefficient of Mixture) is introduced to assess the mixing degree of the two gases in the pipeline. According to industry standards, a COV < 5% is generally considered sufficient mixing. This study demonstrates a direct correlation between COV and the mixing of hydrogen and methane; a lower COV corresponds to a higher level of sufficient mixing. Using the variance of the mixed gas concentration (COV) as the objective function, the optimal injection angle and branch pipe layout are determined. The formula for calculating COV is: ; in, This represents the hydrogen mole fraction at each point on a given cross-section. This represents the arithmetic mean of the hydrogen mole fractions on the selected cross section; This represents the total number of points sampled from the cross section.

[0031] S4. Manufacture the tangential branch pipe assembly according to the optimized parameters and conduct a uniformity test on the experimental platform. S5. Adjust the design parameters based on the experimental feedback results to achieve closed-loop optimization of the method.

[0032] Example 1 This invention provides a tangential branch pipe design structure for a hydrogen-blended natural gas pipeline. This example illustrates a single tangential branch pipe (e.g., in the design method for a hydrogen-blended natural gas pipeline) in this context. Figure 2 Embodiment 1 of the present invention provides: a main pipe 1, a branch pipe 2, a front flange 3, a rear flange 4, a main pipe air inlet 5, a branch pipe air inlet 6, an air outlet 7, and a flow field detection module 8.

[0033] A single tangential branch pipe is connected tangentially to the outer diameter of the main pipe 1 via the outer diameter of branch pipe 2, forming a fixed assembly structure. The front flange 3 connects to the main pipe inlet 5 of the main pipe 1, and the rear flange 4 connects to the outlet 7. Main pipe 1 diameter... The diameter d of branch pipe 2 is 0.4m, and the distance between the main air inlet 5 and branch pipe 2 is 0.8m. The distance between branch pipe 2 and air outlet 7 is The angle between branch pipe 2 and main pipe 1 The angle between the hydrogen inlet direction of branch pipe 2 and the direction of gravity is 90°. The angle is 90°. The main pipe 1 receives natural gas, while the branch pipe 2 receives hydrogen. Flow field monitoring module 8 is used to detect the gas velocity and concentration distribution in the mixing area. The fluid inside the pipeline is a natural gas-hydrogen blend; this device and its design method are suitable for natural gas-hydrogen blending transportation pipeline systems. The tangential pipe injects hydrogen from the side of the pipeline rather than from the bottom, making it more suitable for the complex conditions of the seabed environment.

[0034] When hydrogen enters the main pipe, it mixes with methane gas and, under the inertial force of the main pipe, undergoes a clockwise spiral motion inside the pipe, thus forming a vortex structure, which promotes the mixing of the two gases.

[0035] Example 2 This invention provides a tangential branch pipe design structure for a hydrogen-blended natural gas pipeline. This example illustrates a symmetrical tangential double branch pipe design for a hydrogen-blended natural gas pipeline (e.g.,...). Figure 5 Embodiment 2 of the present invention provides: a main pipe 1, a branch pipe 2, a front flange 3, a rear flange 4, a main pipe air inlet 5, a branch pipe air inlet 6, an air outlet 7, and a flow field detection module 8.

[0036] The branch pipe 2 of the symmetrical tangential dual-hydrogen branch pipe is symmetrical about the plane passing through the axis of the main pipe 1. The outer diameter of the branch pipe 2 is tangential to the outer diameter of the main pipe 1 and is connected in a fixed assembly structure. The front flange 3 is connected to the main pipe inlet 5 of the main pipe 1, and the rear flange 4 is connected to the outlet 7. Main pipe 1 diameter... The diameter of branch pipe 2 is 0.8m. The distance is 0.4m, and the distance between the main air inlet 5 and the branch pipe 2 is... The distance between branch pipe 2 and air outlet 7 is The angle between branch pipe 2 and main pipe 1 The angle is 45°, the angle between the hydrogen inlet direction of branch pipe 2 and the direction of gravity. The angle is 90°. The main pipe 1 receives natural gas, while the branch pipe 2 receives hydrogen. Flow field monitoring module 8 is used to detect the gas velocity and concentration distribution in the mixing area. The fluid inside the pipeline is a natural gas-hydrogen blend; this device and its design method are suitable for natural gas-hydrogen blending transportation pipeline systems. The tangential pipe injects hydrogen from the side of the pipeline rather than from the bottom, making it more suitable for the complex conditions of the seabed environment.

[0037] If the angle of the branch pipe in a conventional hydrogen-blended natural gas pipeline is set to , ( Figure 6 If this structure can reduce outlet COV by at least 88.3%, then the symmetrical dual-hydrogen branch pipe with dual hydrogen inlets in the tangential pipe can also reduce COV by at least 88.3%. It is 45°. Compared to the former, the 90° structure reduced the outlet COV by an additional 20.5%, indicating that the symmetrical tangential dual hydrogen branch structure is more effective.

[0038] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. It should be understood that the disclosed technical content in the several embodiments provided in this application can be implemented in other ways.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tangential branch pipe for a hydrogen-blended natural gas pipeline, suitable for a natural gas hydrogen-blended transportation pipeline system, characterized in that, include: Main pipe (1), branch pipe (2), front flange (3), rear flange (4), main pipe inlet (5), branch pipe inlet (6), outlet (7) and flow field monitoring module (8); The two ends of the main pipe (1) are the main pipe inlet (5) and the outlet (7), respectively; there is at least one branch pipe (2); the branch pipe (2) is tangentially connected to the outer diameter of the main pipe (1) and used for hydrogen injection; the front flange (3) and the rear flange (4) are used for sealing connection of the pipe section; the flow field monitoring module (8) is used to detect the gas flow rate and concentration distribution in the mixing area.

2. A tangential branch pipe of a hydrogen-blended natural gas pipeline according to claim 1, characterized in that, The branch pipe (2) is a single branch pipe, a double branch pipe, or a multi-branch pipe that is tangential to the main pipe (1).

3. A tangential branch pipe of a hydrogen-blended natural gas pipeline according to claim 1, characterized in that, The angle between the branch pipe (2) and the main pipe axis is: The angle between the airflow direction in the branch pipe and the direction of gravity is... .

4. A tangential branch pipe of a hydrogen-blended natural gas pipeline according to claim 1, characterized in that, When the branch pipe (2) is a double branch pipe; if the double branch pipe is a symmetrical double branch pipe and the main pipe is tangent to each other, the two branch pipes are mirror symmetrical about a plane passing through the axis of the main pipe; if the double branch pipe is an asymmetrical double branch pipe and the main pipe is tangent to each other, the two branch pipes are centrally symmetrical about the axis of the main pipe.

5. A tangential branch pipe of a hydrogen-blended natural gas pipeline according to claim 1, characterized in that, The branch pipe (2) is connected to the main pipe (1) by a flange or a threaded connection.

6. A tangential branch pipe of a hydrogen-blended natural gas pipeline according to claim 1, characterized in that, The gas entering the main pipe (1) is natural gas; the gas entering the branch pipe (2) is hydrogen.

7. A method for evaluating the performance of tangential branch pipes in a hydrogen-blended natural gas pipeline, using the tangential branch pipe described in any one of claims 1-6, characterized in that... Includes the following steps: S1. Establish the geometric model of the main pipe and branch pipes, and define the ratio of the hydrogen gas position to the diameter at the inlet. Angle and included angle ; S2. CFD numerical simulation was used to calculate the flow field distribution of hydrogen and natural gas at different angles; S3. Introduce COV to assess the degree of mixing of the two gases in the pipeline; according to industry standards, when COV < 5%, the mixing is generally considered sufficient. S4. Manufacture the tangential branch pipe assembly according to the optimized parameters and conduct a uniformity test on the experimental platform. S5. Adjust the design parameters based on the experimental feedback results to achieve closed-loop optimization of the method.

8. The method for evaluating the performance of tangential branch pipes in a hydrogen-blended natural gas pipeline according to claim 7, characterized in that, The formula for calculating COV is: ； in, This represents the hydrogen mole fraction at each point on a given cross-section. This represents the arithmetic mean of the hydrogen mole fractions on the selected cross section; This represents the total number of points sampled from the cross section.

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