Static mixer nozzle structure, natural gas hydrogen conveying system and method for improving gas mixing uniformity

Abstract

The invention discloses a static mixer nozzle structure, a natural gas hydrogen delivery system and a method for improving gas mixing uniformity, the static mixer nozzle structure comprises: a cylinder, the two axial ends of which are respectively provided with a first gas inlet and a mixed gas outlet, and the side wall of the cylinder is provided with a second gas inlet; the nozzle pipeline is mounted on the side wall of the cylinder body, is communicated with the second gas inlet and is used for spraying second gas into the cylinder body; one end of the nozzle pipeline is arranged in the cylinder body, and a plurality of openings are formed in the part, in the cylinder body, of the nozzle pipeline; and the flow guide part is fixedly mounted in the cylinder body, is positioned at the downstream of the nozzle pipeline, and is used for mixing airflow from the first gas inlet and the nozzle pipeline.

Description

Technical Field

[0001] This invention relates to the field of gas mixing technology, specifically to a static mixer nozzle structure, a natural gas hydrogen transport system, and a method for improving gas mixing uniformity. Background Technology

[0002] With the transformation of the energy structure and the development of a low-carbon economy, the importance of hydrogen energy as a clean energy source is becoming increasingly prominent. Blending hydrogen into natural gas pipelines is one effective way to achieve large-scale transportation and utilization of hydrogen energy. However, due to significant differences in the density, viscosity, and other physical properties of hydrogen and natural gas, they are difficult to mix naturally and uniformly.

[0003] The static mixer nozzles currently used in natural gas hydrogen transportation systems mainly suffer from the following problems: 1. Uneven mixing of hydrogen and natural gas can easily create a concentration gradient, affecting combustion efficiency; 2. Existing nozzle structures are simple, mostly straight holes with a single aperture, which cannot achieve uniform hydrogen injection; 3. High-speed hydrogen injection may cause the Venturi effect, resulting in excessively low local pressure and cavitation. Chinese patent CN212690144U discloses a static mixer, including a cylinder, a reducing agent nozzle assembly, and a flow guide, aiming to solve the problem of reducing agent crystallization and blockage. However, this design is mainly aimed at the tail gas treatment field and does not consider the special requirements of hydrogen and natural gas mixing, especially the problem of mixing uniformity. Therefore, there is an urgent need to develop a static mixer nozzle structure specifically for natural gas hydrogen transportation systems to improve the mixing uniformity of hydrogen and natural gas while ensuring the safe and reliable operation of the system. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a static mixer nozzle structure, a natural gas hydrogen transportation system, and a method for improving gas mixing uniformity, in order to overcome at least one related technical problem existing in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A static mixer nozzle structure includes: a cylindrical body, serving as the main container for the mixing reaction and a gas flow channel. To create a continuous, closed mixing space, the cylindrical body is configured with a first gas inlet and a mixed gas outlet at both axial ends, and a second gas inlet is opened on its side wall. A first gas (such as natural gas) enters through the first gas inlet to form the main flow, and the mixed gas eventually flows out from the mixed gas outlet. The cylindrical body is typically cylindrical, but can also be designed as rectangular or other cross-sectional shapes as needed.

[0006] A nozzle pipe is installed on the side wall of the cylinder and communicates with the second gas inlet for injecting a second gas into the cylinder; one end of the nozzle pipe is built into the cylinder, and the portion of the nozzle pipe inside the cylinder has multiple openings; its position is located upstream of the guide member.

[0007] A flow guide, fixedly installed inside the cylinder and located downstream of the nozzle duct, is used to mix the airflow from the first gas inlet and the nozzle duct. As the airflow passes through, the flow guide disrupts the flow field through its structure, generating strong shear and turbulence, thereby breaking up airflow stratification and promoting uniform mixing of the gas at the molecular scale.

[0008] In order to create a complex flow field in the early stages of injection to promote mixing, in some alternative embodiments, the plurality of openings in the nozzle duct include at least a first type of opening and a second type of opening. The opening of the first type of opening faces the first gas inlet; the opening of the second type of opening is located on both sides of the first type of opening.

[0009] In some alternative embodiments, the first type of opening is shaped like an inverted isosceles trapezoid; the second type of opening is shaped like a right trapezoid, with the right-angled side vertically positioned on the centerline of the side nozzle pipe and facing the first gas inlet. The first and second types of openings can also adopt other shapes that achieve similar gas diffusion or guiding functions, such as a trumpet shape, a venturi shape, or a rectangle with rounded corners, but the effect is not as good as that of the inverted isosceles trapezoid and the right trapezoid.

[0010] In some optional embodiments, the trapezoidal lower base of the first type of opening has a length of 5-15 mm, the upper base has a length of 1.2-8 times the length of the lower base, and the height has a length of 50-150 mm; and / or, the trapezoidal lower base of the second type of opening has a length of 4-20 mm, the upper base has a length of 0.1-0.8 times the length of the lower base, and the height has a length of 50-150 mm.

[0011] In some alternative embodiments, the flow guide includes multiple blade groups arranged along the axial direction of the cylinder, each blade group consisting of multiple circumferentially distributed blades, with flow channels formed between adjacent blades.

[0012] In some alternative embodiments, the axial distance between the starting end of the guide and the nozzle pipe is 0.2-1.5 times the diameter of the cylinder.

[0013] In some optional embodiments, a monitoring unit disposed on the cylinder wall is also included, the monitoring unit being used to monitor the gas state parameters inside the cylinder.

[0014] In some alternative implementations, the monitoring unit includes at least one of a hydrogen concentration sensor and a temperature sensor.

[0015] This embodiment also provides a natural gas hydrogen transportation system, including any of the static mixer nozzle structures described in the previous embodiment, wherein the first gas inlet is used to introduce natural gas, and the second gas inlet is used to introduce hydrogen.

[0016] This embodiment also provides a method for improving the uniformity of gas mixing, which adopts any of the static mixer nozzle structures described above, so that the first gas flows in from the first gas inlet, the second gas is injected into the cylinder through the nozzle pipe, and the mixed gas flow out from the mixed gas outlet after passing through the guide member.

[0017] The beneficial effects that the static mixer nozzle structure, natural gas hydrogen transportation system, and method for improving gas mixing uniformity disclosed in this application may bring include, but are not limited to: 1. Extremely high mixing uniformity: Through unique nozzle pipe design and blade guide structure, the mixing uniformity of hydrogen and natural gas is significantly improved, reaching over 95%.

[0018] 2. Reduced system pressure: Optimized nozzle shape and size, reasonable component spacing, and efficient flow guiding structure work together to reduce unnecessary flow resistance and significantly reduce system energy consumption.

[0019] 3. High safety and reliability: The integrated real-time status monitoring unit (such as concentration and temperature sensors) enables online monitoring and safety early warning of the mixing process, greatly improving the reliability and safety of the system operation.

[0020] 4. Wide range of adaptability: The structural design parameters have been optimized to adapt to different hydrogen blending ratios (such as 5%-30%) and a wide range of flow rate changes, and it has good robustness.

[0021] 5. Modular and easy to maintain: The structure is clear, the functions of the components are well-defined, and it is easy to produce, install, and clean and maintain in a modular manner. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the static mixer nozzle structure according to an embodiment of this application.

[0023] Figure 2 This is a front view of the nozzle pipe according to an embodiment of this application.

[0024] Figure 3 This is a left view of the nozzle pipe according to an embodiment of this application.

[0025] Figure 4 This is a right view of the nozzle pipe according to an embodiment of this application.

[0026] Figure 5 This is a cloud map of the mixture of natural gas and hydrogen according to an embodiment of this application.

[0027] The labels in the diagram are as follows: 1-Cylinder body, 2-Nozzle pipe, 3-Type I opening, 4-Type II opening, 5-Monitoring unit, 6-Flow guide. Detailed Implementation

[0028] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0030] like Figure 1-4 As shown, this invention first proposes a basic architecture for a static mixer nozzle structure. This structure creatively employs a synergistic mechanism combining "upstream premixing" and "downstream forced mixing." Specifically, it includes a cylindrical body serving as a mixing reaction chamber, with a first gas inlet and a mixed gas outlet at its axial ends, and a second gas inlet on its side wall to create a continuous airflow channel. To efficiently and dispersedly introduce the second gas into the main stream of the first gas, a nozzle pipe is installed on the side wall of the cylindrical body and communicates with the second gas inlet; this component has multiple openings distributed along the axial direction of the cylindrical body.

[0031] To achieve deep and forced mixing of the initially converging gas streams, a guide vane is fixedly installed inside the cylinder, precisely downstream of the nozzle duct. During operation, a first gas (such as natural gas) flows in axially, while a second gas (such as hydrogen) is injected through multiple openings in the nozzle duct, initially merging with it. Subsequently, the mixed gas stream passes through the guide vane, whose internal structure generates intense shearing and turbulence, completely breaking down gas stratification and achieving uniform mixing at the molecular scale. This fundamental structure optimizes the mixing path, providing a fundamental physical solution to the problem of inhomogeneous mixing.

[0032] To create a more complex flow field in the initial injection stage, further enhance the initial mixing effect, and create conditions for downstream deep mixing, this invention optimizes the design of the nozzle pipe. Its multiple openings are specifically divided into a first type of opening and a second type of opening. The opening direction of the first type of opening faces the first gas inlet; the opening directions of the second type of opening are located on both sides of the first type of opening. Specifically, the opening direction of the first type of opening is set to form an angle of approximately 90 degrees with the mainstream gas flow direction, so that a portion of the natural gas entering from the first gas inlet enters the nozzle pipe through the first type of opening, undergoes initial mixing with the hydrogen therein, and then exits from the second type of opening on both sides. The injected natural gas jet and hydrogen jet meet within the nozzle pipe, generating intense momentum exchange and shearing. Simultaneously, the opening direction of the second type of opening is set to be approximately perpendicular to the mainstream gas flow direction, allowing the initially mixed gas and hydrogen jet to cut into the mainstream natural gas from the side, forming effective lateral impact and entrainment. This composite jetting mode, combining "forward shearing" and "lateral impact," can disturb the mainstream and break the boundary layer in multiple dimensions from the very beginning of mixing, generating multi-scale eddies. This significantly enhances the intensity and uniformity of the initial mixing. (See details...) Figure 5 , Figure 5 In the diagram, the blue part represents natural gas, the red part represents hydrogen, and the yellow-green part represents a mixture of natural gas and hydrogen.

[0033] Furthermore, to optimize the flow field characteristics of the airflow entering from the first type of opening and exiting from the second type of opening, making it more conducive to mixing, this invention specifically designs the shapes of the two types of openings. The first type of opening is shaped like an inverted isosceles trapezoid; the second type of opening is shaped like a right-angled trapezoid, with the right-angled side vertically positioned and located on the centerline of the side nozzle duct, facing the first gas inlet. It should be noted that the right-angled side of the right-angled trapezoid referred to here is its height. See also... Figure 2 The fact that the right-angled side is located on the center line of the side nozzle pipe means that, when viewed from the front view of the nozzle pipe, there is no gap in the outer contour of the nozzle pipe.

[0034] The first type of opening narrows at the bottom and widens at the top of the two side openings. This is designed to reduce the amount of natural gas flowing to the rear end of the hydrogen pipeline, prompting the natural gas flow to mix with hydrogen along the pipeline and flow out promptly, thereby preventing natural gas from migrating to the end and accumulating. Preferably, it is an inverted isosceles trapezoid. The second type of openings on both sides adopts a right-angled trapezoidal structure with an expanded lower base, and the right-angled side is located on the centerline of the side nozzle pipeline. By increasing the lateral flow cross-sectional area, the gas diffusion capacity is enhanced, the growth of the natural gas flow is suppressed, and the natural gas and hydrogen are fully premixed and flow out uniformly from the second type of openings on both sides.

[0035] Given that the nozzle pipe is a circular pipe structure, when natural gas flows inside the cylinder after injection, the pipe wall obstructs the flow, creating a positive pressure zone perpendicular to the nozzle pipe axis on the windward side and a negative pressure zone on the anterowind side. This design specifically utilizes these pressure distribution characteristics: the shape of the second type of openings on both sides is preferably a right-angled trapezoid. The right-angled sides of the trapezoidal openings are aligned with the centerline of the nozzle pipe, which avoids the inhibitory effect of the positive pressure zone on the outflow of the mixed gas, and also enhances the outflow momentum of the mixed gas by utilizing the negative pressure on the anterowind side, further improving mixing uniformity and outflow efficiency.

[0036] To ensure the stable and efficient operation of both the first and second type of openings under a wide range of working conditions, this invention determined the key structural dimension ranges through fluid dynamics simulation and experimental verification. For the isosceles trapezoidal first type of opening, the preferred length of the lower base is 5-15 mm, the length of the upper base is 1.2-8 times that of the lower base, and the height is 50-150 mm. For the right-angled trapezoidal second type of opening, the preferred length of the lower base is 4-20 mm, the length of the upper base is 0.1-0.8 times that of the lower base, and the height is also 50-150 mm. These dimension ranges ensure that the nozzle provides sufficient gas flow and jet power while avoiding momentum dispersion due to an excessively large opening or local pressure drop surges and whistling risks caused by an excessively small opening. The nozzle has a certain axial extension height, making its jet "band-shaped" rather than "point-shaped," increasing the contact area and time with the mainstream, which is a key structural parameter for achieving high mixing uniformity and low pressure drop.

[0037] Regarding the flow guide, its internal structure is designed to generate continuous and intense three-dimensional turbulence. Specifically, it comprises multiple blade groups arranged along the axial direction of the cylinder, each blade group consisting of multiple circumferentially distributed blades, forming complex flow channels between adjacent blade groups. When the initially mixed airflow passes through, each blade group divides and guides the airflow, forcing it to continuously change its speed and direction. The cascading action of multiple blade groups allows turbulence to be repeatedly generated, developed, and reorganized, thereby greatly extending the effective disturbance path and mixing time of the airflow within the mixing unit, achieving deep and refined mixing of the gas, with an efficiency far exceeding that of a single-stage flow guide structure.

[0038] The flow guide is existing technology and will not be discussed in detail here. For example, it can be implemented using an SMX mixing unit or an SMX mixer.

[0039] To ensure a seamless transition and optimal synergistic effect between the "preliminary mixing" and "deep mixing" stages, this invention optimizes the axial layout between the nozzle duct and the guide vane. The axial distance between the starting end of the guide vane and the nozzle duct is limited to 0.2-1.5 times the cylinder diameter. This is a critical, optimized spacing. If the distance is too short, the injected gas will be disturbed before it has fully diffused, resulting in poor mixing efficiency and potentially increased pressure drop; if the distance is too long, the airflow after preliminary mixing may stabilize again, wasting cylinder length. This preferred distance ensures that the airflow has undergone adequate penetration and convergence before entering the guide vane, placing it in an ideal state most conducive to deep disturbance, thus achieving an optimal balance between overall mixing effect and energy consumption.

[0040] To improve system safety and reliability and achieve intelligent monitoring, this invention incorporates a monitoring unit on the cylinder wall. This unit monitors key gas state parameters (such as concentration, temperature, and pressure) within the cylinder in real time, addressing safety hazards arising from the invisibility and unknowability of the mixing process (e.g., excessively high hydrogen concentration due to uneven local mixing). The monitoring data can be used to determine the mixing uniformity and equipment operating status in real time, providing a foundation for closed-loop control and fault early warning.

[0041] For the specific and important application scenario of natural gas-hydrogen transportation, the monitoring unit is specifically configured as a hydrogen concentration sensor and / or a temperature sensor. The hydrogen concentration sensor directly monitors the hydrogen concentration at the outlet or downstream critical cross-section, serving as the most direct indicator for assessing mixing uniformity; abnormal concentrations trigger immediate alarms. The temperature sensor monitors temperature fluctuations caused by gas throttling and expansion, abnormal equipment friction, or environmental changes, providing another important early warning indicator for safe system operation. The use of these two sensors enables precise and targeted monitoring of core risk parameters.

[0042] This invention also applies the aforementioned efficient and safe static mixer nozzle structure to a complete natural gas-hydrogen transmission system. In this system, the first gas inlet is connected to a natural gas source, and the second gas inlet is connected to a hydrogen source. The mixer functions as the core unit. Natural gas continuously flows in axially, while hydrogen, after precise metering and pressure regulation, is injected through an optimized nozzle pipeline. The two undergo efficient preliminary and deep mixing within the cylinder, forming a uniform and stable hydrogen-blended natural gas, which is ultimately transported to downstream pipelines or users. This system provides a comprehensive solution for hydrogen pipeline transportation that offers high mixing efficiency and reliable operation.

[0043] This invention provides a method for improving gas mixing uniformity using any of the above-mentioned static mixer nozzle structures. First, a first gas (such as natural gas) flows axially into the cylinder to form the mainstream. Then, a second gas (such as hydrogen) is introduced through a nozzle pipe on the side wall. Through a first-type opening, the natural gas and hydrogen are pre-mixed within the nozzle pipe, and then injected into the mainstream from the second-type openings on both sides in a shape-optimized pattern, completing preliminary momentum exchange and shear mixing. Finally, the mixed gas flow passes through a downstream guide component, where its multi-stage blade structure generates intense three-dimensional turbulence, achieving final deep homogenization of the gas before output. This method organically combines macroscopic momentum exchange with microscopic turbulent diffusion, forming a highly efficient and reliable mixing process.

[0044] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A static mixer nozzle structure, characterized in that, include: The cylinder has a first gas inlet and a mixed gas outlet at its two axial ends, and a second gas inlet on its side wall. A nozzle pipe is installed on the side wall of the cylinder and communicates with the second gas inlet for injecting a second gas into the cylinder; one end of the nozzle pipe is built into the cylinder, and the portion of the nozzle pipe inside the cylinder has multiple openings. A flow guide is fixedly installed inside the cylinder and located downstream of the nozzle pipe, for mixing the airflow from the first gas inlet and the nozzle pipe.

2. The static mixer nozzle structure according to claim 1, characterized in that: The plurality of openings in the nozzle duct include at least a first type of opening and a second type of opening; The opening of the first type of opening faces the first gas inlet; the opening of the second type of opening is located on both sides of the first type of opening.

3. The static mixer nozzle structure according to claim 2, characterized in that: The first type of opening is shaped like an inverted isosceles trapezoid; the second type of opening is shaped like a right trapezoid with the right-angled side vertically positioned, the right-angled side located on the centerline of the side nozzle pipe, and the right-angled side facing the first gas inlet.

4. The static mixer nozzle structure according to claim 3, characterized in that: The trapezoidal lower base of the first type of opening has a length of 5-15mm, the upper base has a length of 1.2-8 times the length of the lower base, and the height has a length of 50-150mm; and / or, the trapezoidal lower base of the second type of opening has a length of 4-20mm, the upper base has a length of 0.1-0.8 times the length of the lower base, and the height has a length of 50-150mm.

5. The static mixer nozzle structure according to claim 1, characterized in that: The flow guide includes multiple blade groups arranged along the axial direction of the cylinder. Each blade group consists of multiple blades distributed circumferentially, and flow channels are formed between adjacent blades.

6. The static mixer nozzle structure according to claim 5, characterized in that: The axial distance between the starting end of the guide and the nozzle pipe is 0.2-1.5 times the diameter of the cylinder.

7. The static mixer nozzle structure according to claim 1, characterized in that: It also includes a monitoring unit installed on the cylinder wall, which is used to monitor the gas state parameters inside the cylinder.

8. The static mixer nozzle structure according to claim 7, characterized in that: The monitoring unit includes at least one of a hydrogen concentration sensor and a temperature sensor.

9. A natural gas hydrogen transportation system, characterized in that: The static mixer nozzle structure includes any one of claims 1 to 8, wherein the first gas inlet is for introducing natural gas and the second gas inlet is for introducing hydrogen.

10. A method for improving the uniformity of gas mixing, characterized in that: The static mixer nozzle structure as described in any one of claims 1 to 8 is adopted, in which a first gas flows in from the first gas inlet, a second gas is injected into the cylinder through the nozzle pipe, and the mixed gas flow out from the mixed gas outlet after passing through the guide member.

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