Mixer for promoting mixing of natural gas and hydrogen in hydrogen natural gas pipeline

Abstract

The utility model discloses a mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline, the mixer is additionally arranged in a natural gas hydrogen-doped pipeline or a fluctuating pipeline, the mixer is composed of a main body axis structure and a straight thread structure, and a gas inlet is arranged in the main body axis structure. Notches are formed in the two ends of the straight thread structure, so that fluid can enter / flow out easily. Due to the existence of the main body axis structure and the air inlet, the fluid area in front of the main body axis structure is suddenly reduced, the flow speed is increased, and pressure difference is formed before and after the main body axis structure, so that mixing is promoted. Mixed gas can flow along the straight threads around the axis type structure of the main body while flowing through the axis type structure of the main body, and the mixed gas is continuously and intensely mixed and diffused through flow division, radial mixing and reverse rotation, so that mixing is promoted.

Description

Technical Field

[0001] The utility model belongs to the technical field of hydrogen mixing and transportation in natural gas pipelines, and relates to a mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline. Background Art

[0002] At present, an important research direction on how to achieve large-scale transportation and large-scale utilization of hydrogen is to mix hydrogen with natural gas for transportation. After 2000, research on hydrogen blending technology and application of natural gas pipelines has been carried out successively. Many countries have released hydrogen energy development roadmaps and hydrogen energy investment for the hydrogen energy field. This momentum is accelerating the cost reduction of hydrogen production, storage, transportation, distribution, retail and terminal applications in the industrial chain, accelerating its large-scale application, and achieving unprecedented global linkage in history. Many natural gas pipeline hydrogen blending and transportation demonstration projects have been carried out at home and abroad.

[0003] However, due to the large difference in density between hydrogen and natural gas, the density of natural gas at room temperature and pressure is about 8 times that of hydrogen, and hydrogen is easier to diffuse than natural gas. The existing mixing device has a complex structure and uneven mixing. With the addition of hydrogen, the hydrogen-blended natural gas will have an uneven volume fraction distribution under the action of gravity during storage and pipeline shutdown, which will cause the local hydrogen partial pressure and volume fraction of the pipeline to increase, leading to pipe failure and leakage, and will also make it inconvenient for end users to use. Utility Model Content

[0004] The utility model aims to solve the problems of complicated structure and uneven mixing of the mixing device in the prior art, and to provide a mixer for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model proposes a mixer for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline, comprising a main shaft structure and a straight thread structure;

[0007] The straight thread structure is wound around the outer wall surface of the main body axis structure; an air inlet is arranged inside the main body axis structure, and the air inlet runs through the upper and lower surfaces of the main body axis structure; and notches are arranged at both ends of the straight thread structure.

[0008] Preferably, the thread pitch, thread width and thread depth between the threads of the thread structure are the same, and the rotation angle remains unchanged.

[0009] Preferably, there are several air inlets.

[0010] Preferably, the plurality of air inlets are evenly distributed.

[0011] Preferably, the air inlets have equal diameters.

[0012] Preferably, the sum of the areas of the plurality of air inlets is smaller than the cross-sectional area of ​​the straight thread structure.

[0013] Preferably, the air intake pressure of the air intake port is greater than the air intake pressure of the straight thread structure.

[0014] Preferably, the main body axis structure is a columnar structure.

[0015] Preferably, the main body axis structure and the straight thread structure are both made of stainless steel.

[0016] Preferably, the diameter of the air inlet is smaller than the thread depth of the thread structure.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] The utility model proposes a mixer that promotes the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline. Under the premise of simplifying the pipeline structure as much as possible and reducing the dissipation of gas heat energy, the stratification phenomenon of natural gas and hydrogen is suppressed, and high-quality mixing of natural gas and hydrogen is achieved. Specifically, there are two air inlets and one air outlet in the natural gas hydrogen-blended pipeline. The air inlet on the main pipeline is the main air inlet for introducing natural gas, and the air inlet on the branch pipeline is the secondary air inlet for introducing hydrogen. The mixer is installed in the natural gas hydrogen-blended pipeline or in the undulating pipeline. The mixer consists of a main axis structure and a straight thread structure, and an air inlet is provided inside the main axis structure. Notches are provided at both ends of the straight thread structure to facilitate the entry / outflow of fluid. Among them, due to the existence of the main axis structure and the air inlet, the fluid area in front of the main axis structure will suddenly decrease, and the flow rate will increase, resulting in a pressure difference before and after the main axis structure, thereby promoting mixing. While the mixed gas flows through the main axial structure, it also flows along the straight threads around the main axial structure. Through flow segmentation, radial mixing, and reverse rotation, the mixed gas is continuously and intensely mixed and diffused, thereby promoting mixing. The combination of the two structures will improve the gas mixing efficiency and enhance the mixing ability. Therefore, with the cooperation of this mixer, natural gas and hydrogen, two gases of different properties, can achieve better mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a structural diagram of a mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to the utility model.

[0021] Figure 2 The utility model provides a pressure distribution cloud diagram (absolute pressure) of a hydrogen-blended natural gas pipeline when the CH4 intake velocity at the primary intake port is 1.5 m / s and the H2 intake velocity at the secondary intake port is 4 m / s.

[0022] Figure 3 The utility model provides a pressure distribution cloud diagram (total pressure) of a hydrogen-blended natural gas pipeline when the CH4 intake velocity at the primary intake port is 1.5 m / s and the H2 intake velocity at the secondary intake port is 4 m / s.

[0023] Figure 4 The utility model provides a velocity streamline diagram of a hydrogen-blended natural gas pipeline when the CH4 intake velocity at the primary intake port is 1.5 m / s and the H2 intake velocity at the secondary intake port is 4 m / s.

[0024] Figure 5 The utility model is an installation situation of the mixer in the natural gas hydrogen blending pipeline.

[0025] Figure 6 The utility model is installed in the mixer in the undulating pipeline.

[0026] Figure 7 This is the arrangement of air inlets provided by the utility model ((a) is a schematic diagram of the arrangement of air inlets of the first main body axis structure; (b) is a schematic diagram of the arrangement of air inlets of the second main body axis structure; (c) is a schematic diagram of the arrangement of air inlets of the third main body axis structure; (d) is a schematic diagram of the arrangement of air inlets of the fourth main body axis structure; (e) is a schematic diagram of the arrangement of air inlets of the fifth main body axis structure).

[0027] Figure 8 It is a schematic diagram of the straight thread structure provided by the utility model ((a) is a schematic diagram of the structure of the first straight thread structure; (b) is a schematic diagram of the structure of the second straight thread structure; (c) is a schematic diagram of the structure of the third straight thread structure).

[0028] Among them: 1-main axis structure, 2-straight thread structure, 3-air inlet, 4-natural gas hydrogen blending pipeline, 5-undulating pipeline. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the embodiments of the present utility model, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use, it is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of the present utility model, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0035] The utility model is further described in detail below with reference to the accompanying drawings:

[0036] like Figure 1 As shown, the utility model proposes a mixer for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline, comprising a main shaft structure 1 and a straight thread structure 2; the straight thread structure 2 is wound around the outer wall of the main shaft structure 1; an air inlet 3 is provided inside the main shaft structure 1, and the air inlet 3 runs through the upper and lower surfaces of the main shaft structure 1, and notches are provided at both ends of the straight thread structure 2. Among them, the main shaft structure 1 is a columnar structure.

[0037] Under the premise of simplifying the pipeline structure as much as possible and reducing the dissipation of gas heat energy, the stratification phenomenon of natural gas and hydrogen is suppressed to achieve high-quality mixing of natural gas and hydrogen. Specifically, the natural gas hydrogen blending pipeline 4 has two air inlets and one air outlet. The air inlet on the main pipeline is the main air inlet for introducing natural gas, and the air inlet on the branch pipeline is the secondary air inlet for introducing hydrogen. The mixer is installed in the natural gas hydrogen blending pipeline 4 or in the undulating pipeline 5. The mixer consists of a main axis structure 1 and a straight thread structure 2, and an air inlet 3 is provided inside the main axis structure 1. Notches are provided at both ends of the straight thread structure 2 to facilitate fluid entry / outflow. Among them, due to the presence of the main axis structure 1 and the air inlet 3, the fluid area in front of the main axis structure 1 will suddenly decrease, and the flow rate will increase, resulting in a pressure difference before and after the main axis structure 1, thereby promoting mixing. While the mixed gas flows through the main axial structure 1, it also flows along the straight threads around the main axial structure 1. Through flow segmentation, radial mixing, and reverse rotation, the mixed gas is continuously and intensely mixed and diffused, thereby promoting mixing. The combination of the two structures will improve the gas mixing efficiency and enhance the mixing ability. Therefore, with the cooperation of this mixer, natural gas and hydrogen, two gases of different properties, can achieve better mixing.

[0038] Preferably, the thread pitch, thread width and thread depth between the threads of the thread structure 2 are the same, and the rotation angle remains unchanged. This arrangement has the following advantages: since all thread parameters are consistent, this thread structure can be easily standardized. Standardized threads enhance the interchangeability between different components and reduce production and maintenance costs. Since the thread pitch, width and depth are the same, when the thread is subjected to external force, the load will be evenly distributed on each thread, reducing the risk of stress concentration and local damage. The unchanged rotation angle means that the thread always maintains a stable meshing state during the rotation process, which increases the stability and reliability of the threaded connection. Since all thread parameters are the same, this thread structure is easier to automate and mass-produce during the manufacturing process, improving production efficiency.

[0039] There are a plurality of air inlets 3, and the plurality of air inlets 3 are evenly distributed, and the diameters of the air inlets 3 are equal. When the plurality of air inlets 3 are evenly distributed, the resistance to air flow is reduced, which helps to improve the air intake efficiency.

[0040] The sum of the areas of the plurality of air inlets 3 is smaller than the cross-sectional area of ​​the straight thread structure 2. The air inlet pressure of the air inlet 3 is greater than the air inlet pressure of the straight thread structure 2. The diameter of the air inlet 3 is smaller than the thread depth of the thread structure 2.

[0041] The main shaft structure 1 and the straight thread structure 2 are both made of stainless steel. The stainless steel material itself has high strength and quality stability, which enables the main shaft structure 1 and the straight thread structure 2 to withstand large loads and torques, ensuring the stable operation of the equipment. The high temperature oxidation resistance of stainless steel enables it to maintain high strength in high temperature environments and is suitable for various high temperature working environments. Stainless steel has excellent corrosion resistance and can resist the erosion of a variety of chemical substances, which enables the main shaft structure 1 and the straight thread structure 2 to maintain a long service life in harsh environments.

[0042] like Figure 5 As shown, the installation of the mixer in the natural gas hydrogen blending pipeline 4 is as follows: Figure 6 As shown, the mixer is installed in the undulating pipeline 5, and the length of the mixer is 1000-3000mm. The diameter of the natural gas hydrogen blending pipeline 4 or the undulating pipeline 5 ranges from 400mm to 800mm, and the mixer can be installed at 1 / 3, 2 / 5, or 3 / 5 of the entrance of the natural gas hydrogen blending pipeline 4 or the undulating pipeline 5. The number of air inlets 3 is 3-13, and the arrangement of the air inlets can be as follows: Figure 7 As shown, (a) is a triangular arrangement, (b) is a quadrilateral arrangement, (c) is a pentagonal arrangement, (d) is a hollow hexagonal arrangement, (e) is a solid hexagonal arrangement, and so on. The air inlet diameter is 30-60mm. The pitch range of the straight thread structure 2 is 100mm-200mm, the outer diameter is 400-800mm, the inner diameter is 200-600mm, the number of threads is 10-15, the thread width is 100-200mm, the thread starting angle is 180 degrees, and the shape of the straight thread structure can be Figure 8 As shown, (a) is a schematic diagram of the structure of the first straight thread structure, (b) is a schematic diagram of the structure of the second straight thread structure, and (c) is a schematic diagram of the structure of the third straight thread structure. Among them, the main pipeline length of the natural gas hydrogen blending pipeline 4 is 8000mm or more, and the branch pipeline height is 800-1200mm.

[0043] The assembly and installation process of the utility model of a mixer for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline is as follows:

[0044] Step 1: Install the equal-depth and equal-distance straight thread structure 2 along the outer surface circumference of the main axial structure 1.

[0045] Step 2, install and fix the mixer structure inside the pipeline. The natural gas hydrogen blending pipeline has two air inlets and one air outlet, wherein the air inlet on the main pipeline is the primary air inlet, into which natural gas is introduced, and the air inlet on the branch pipeline is the secondary air inlet, into which hydrogen is introduced; valves are used to control the flow of gas through the pipeline, or to complete the cut-off function to improve the safety of the pipeline, etc.

[0046] In order to explore the flow characteristics of the fluid in the perforated screw pipe structure, the non-flow-through parts of the model and some features that do not affect the overall performance are simplified in the three-dimensional mechanical design software SolidWorks (the coordinate origin is at the center of the air inlet on the left surface of the spiral orifice plate pipe structure). The model is imported into the Geometry module in the finite element analysis software ANSYS to extract the flow channel and obtain the internal flow channel geometry model of the structure. After extracting the fluid domain, tetrahedral meshes are used for meshing, with a mesh number of 250,000. When the CH4 velocity at the main air inlet is set to 1.5m / s and the H2 velocity at the secondary air inlet is set to 4m / s, the pressure distribution cloud map and velocity vector cloud map are obtained.

[0047] The mixer of the utility model is simulated by using the software Ansys2022R1. In the pre-processing process, the minimum size of the surface mesh is 0.01m, and the maximum size of the surface mesh is 0.06m. In the solution process, the Realizable k-epsilon model and the standard wall function (SWF) are used. The energy equation is turned on, the component option uses the component transfer model, and the gravity acceleration is set to -9.81m / s 2， The CH4 velocity at the primary air inlet is set to 1.5 m / s, and the secondary air inlet velocity is set to 4 m / s. The simulation results are shown in the attached figure. Figures 2 to 4 shown.

[0048] In order to explore the mixing effect of the screw-type pipe structure with holes, four groups of experiments were designed, including no internal components installed in the hydrogen-blended natural gas pipeline, only the main axial structure installed in the hydrogen-blended natural gas pipeline, only equal-depth and equidistant straight thread structures installed in the hydrogen-blended natural gas pipeline, and the screw-type pipe structure installed in the hydrogen-blended natural gas pipeline. They are called Group 1, Group 2, Group 3, and Group 4 respectively. The experimental results of each group were compared and analyzed, and it was concluded from the analysis results that the installation of the screw-type pipe structure with holes in the hydrogen-blended natural gas pipeline can significantly promote the mixing of hydrogen and natural gas in the pipeline, and can well inhibit the occurrence of stratification.

[0049] Therefore, the utility model proposes a mixer structure for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline. After being installed in the pipeline and under the pipeline transportation conditions, the specific mixing process is as follows:

[0050] The fluid in the pipeline will be divided into two parts, one part passes through the main axial structure, and the other part passes through the equal-depth and equal-distance straight thread structure. No matter which part is mixed, turbulence will be formed in the perforated screw pipeline structure, thereby achieving the mixing of natural gas and hydrogen.

[0051] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mixer for promoting the mixing of natural gas and hydrogen in a hydrogen natural gas pipeline, characterized in that: It comprises a main body axis structure (1) and a straight thread structure (2); The straight thread structure (2) is wound around the outer wall surface of the main body axis structure (1); an air inlet (3) is provided inside the main body axis structure (1), and the air inlet (3) passes through the upper and lower surfaces of the main body axis structure (1); and notches are provided at both ends of the straight thread structure (2).

2. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 1, characterized in that: The thread pitch, thread width and thread depth of the thread structure (2) are the same, and the rotation angle remains unchanged.

3. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 1, characterized in that: There are a plurality of air inlets (3).

4. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 3, characterized in that: A plurality of air inlets (3) are evenly distributed.

5. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 3, characterized in that: The diameters of the air inlets (3) are equal.

6. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 3, characterized in that: The sum of the areas of the plurality of air inlets (3) is smaller than the cross-sectional area of ​​the straight thread structure (2).

7. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 3, characterized in that: The air intake pressure of the air intake port (3) is greater than the air intake pressure of the straight thread structure (2).

8. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 1, characterized in that: The main body axis structure (1) is a columnar structure.

9. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 1, characterized in that: The main body shaft structure (1) and the straight thread structure (2) are both made of stainless steel.

10. The mixer for promoting mixing of natural gas and hydrogen in a hydrogen natural gas pipeline according to claim 1, characterized in that: The diameter of the air inlet (3) is smaller than the thread depth of the thread structure (2).

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