A device and method for uniformly blending hydrogen into natural gas

Abstract

This invention proposes a device and method for uniformly blending hydrogen into natural gas. The blending device includes a premixing system, a final mixing system, and a flow distribution control system. The premixing system connects the natural gas and hydrogen main pipelines and has m premixing units. The w-th group of natural gas and hydrogen branch pipelines are connected to the w-th premixing unit. Each premixing unit has n corresponding natural gas and hydrogen branch pipelines. Each hydrogen branch pipeline is equipped with an ejector, and the mixed gas output end is connected to the hydrogen blending pipeline to the final mixing system. The final mixing system is connected to the natural gas main pipeline to achieve two-stage mixing. The flow distribution control system adjusts the hydrogen supply according to operating parameters to stabilize the hydrogen blending concentration. This invention adopts a two-stage mixing structure. Preliminary mixing is achieved through the pressure difference between hydrogen and natural gas using the ejector, followed by final mixing via the natural gas main pipeline to create artificial turbulence. This results in high mixing efficiency, short mixing length, suitability for large-diameter pipelines, and convenient installation and maintenance.

Description

Technical Field

[0001] This invention belongs to the field of natural gas hydrogen blending, and specifically relates to a device and method for uniformly blending natural gas with hydrogen. Background Technology

[0002] Blending natural gas with hydrogen is an important transitional path to achieve a low-carbon energy transition. Compared with directly building a large-scale pure hydrogen supply system, blending with hydrogen can rely on existing natural gas pipelines, storage and distribution facilities, and end-use facilities, resulting in lower retrofitting costs and faster deployment. By blending green hydrogen produced from renewable energy into natural gas, carbon dioxide emissions from end-use combustion can be effectively reduced, and the absorption capacity of fluctuating power sources such as wind and solar power can be improved, forming a flexible energy system with "electricity-hydrogen-gas" synergy. At the same time, it can also improve the diversification of gas sources, enhance energy security and supply resilience. Under the background of "dual carbon" goals and energy structure optimization, blending natural gas with hydrogen has emission reduction benefits, economic feasibility, and engineering feasibility, making it a clear practical necessity.

[0003] Currently, the mainstream technical solutions for blending hydrogen into natural gas mainly include two methods: T-tube mixing and pipeline-embedded static mixers. The relevant technologies have been disclosed in existing patents.

[0004] CN202320876541.1 discloses a natural gas hydrogen blending device, which is a natural gas hydrogen blending structure based on T-tube mixing. It connects a hydrogen pipeline to a main natural gas pipeline via a T-type interface, utilizing the flow of natural gas within the pipeline to achieve mixing of hydrogen and natural gas. However, its mixing effect is heavily dependent on the natural gas flow rate. When the flow rate is low, effective turbulence cannot be formed, leading to uneven mixing of hydrogen and natural gas. To achieve the desired mixing effect, an excessively long mixing length is required, increasing the project's footprint and construction costs. Furthermore, the mixing uniformity deteriorates further under fluctuating operating conditions (flow rate changes).

[0005] CN202210987654.3 discloses a static mixing device for hydrogen blending in large-diameter natural gas pipelines. This device incorporates a built-in static mixer within the main natural gas pipeline, using a mechanical structure to agitate the fluid and create turbulence, thus achieving the mixing of hydrogen and natural gas. While this device can actively generate turbulence through its mechanical structure, improving mixing uniformity, this technology is only suitable for scenarios with small-diameter main natural gas pipelines and low transport volumes. When applied to large-diameter, high-capacity long-distance natural gas pipelines, the mechanical manufacturing cost of the static mixer increases significantly, and the installation, disassembly, and subsequent maintenance become extremely difficult, making it unsuitable for large-scale industrial applications.

[0006] In addition, when the natural gas supply fluctuates significantly, the two existing technologies mentioned above cannot accurately control the concentration of hydrogen blending, making it difficult to stably achieve the preset hydrogen blending concentration.

[0007] In summary, existing natural gas hydrogen blending technologies suffer from problems such as poor mixing uniformity, narrow range of applicable operating conditions, inconvenient installation and maintenance, and low precision in controlling hydrogen blending concentration. There is an urgent need to develop a natural gas hydrogen blending device and method that can balance ease of installation and maintenance, adaptability to operating conditions, and mixing uniformity, while also accurately controlling the hydrogen blending concentration, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0008] To address the technical problems existing in the prior art, the first aspect of the present invention is to provide a natural gas uniform hydrogen blending device. The second aspect, based on the same inventive concept, also provides a hydrogen blending method based on the aforementioned natural gas uniform hydrogen blending device.

[0009] In this embodiment of the invention, a natural gas uniform hydrogen blending device includes a premixing system and a final mixing system. The premixing system is connected to a main natural gas pipeline and a hydrogen pipeline, respectively, and is used to achieve preliminary mixing of natural gas and hydrogen to form a premixed gas. The premixing system includes m premixing units, with m sets of branch pipelines branched from the main natural gas pipeline and m sets of branch pipelines branched from the hydrogen pipeline. The w-th set of natural gas branch pipelines and the w-th set of hydrogen branch pipelines participating in the premixing are connected to the w-th premixing unit in a one-to-one correspondence, where 1≤w≤m, and m is a positive integer. The w-th premixing unit is equipped with... Root natural gas branch pipe and Each hydrogen gas branch pipe has an ejector installed. The inlet end of the natural gas branch pipe is connected to the natural gas branch pipe corresponding to the premixing unit. The inlet end of each hydrogen branch pipe is connected to the hydrogen branch pipe corresponding to the premixing unit, and each hydrogen branch pipe is matched with a natural gas branch pipe. The value is a positive integer; the outlet end of the hydrogen branch pipe and the outlet end of the corresponding natural gas branch pipe are connected to the main inlet and ejector end of the corresponding ejector, respectively. The mixed gas output end of the ejector is connected to the hydrogen reference pipeline, which is used to output the premixed gas after mixing by the ejector to the final mixing system; the input end of the final mixing system is connected to the output end of the premixing system and connected to the main natural gas pipeline, which is used to perform secondary mixing of the premixed gas and the natural gas in the main natural gas pipeline to form a uniform hydrogen-infused natural gas flow.

[0010] The hydrogen blending method of this invention, based on the above-mentioned natural gas uniform hydrogen blending device, includes the following steps:

[0011] S1. Obtain the radius of the main natural gas pipeline. Natural gas processing capacity Premixed hydrogen concentration And set the target hydrogen concentration after blending natural gas with hydrogen. ;

[0012] Calculate the premix ratio coefficient Hydrogen target concentration ratio coefficient and hydrogen-doped pipelines Flow coefficient ;

[0013] Based on the parameters obtained above, based on the hydrogen-doped pipeline The design flow rate determines the flow control setpoint for the nth hydrogen branch in group w. and the selected ejector The gravitation coefficient n=1,2,……, ;

[0014] S2. Natural gas and hydrogen are initially mixed in a preset ratio using a premixing system. Utilizing the pressure difference between hydrogen and natural gas, natural gas is drawn in through an ejector. The flow rate of the nth hydrogen branch in group w is controlled to the set value by adjusting the regulating valve. Premixing is completed, forming a premixed gas;

[0015] S3. The premixed gas output from the premixing system is sent into the natural gas main pipeline through the final mixing system. The pipeline layout of the final mixing system creates artificial turbulence to achieve uniform mixing of the premixed gas and the natural gas in the natural gas main pipeline.

[0016] S4. In steps S2 and S3, the flow parameters of each hydrogen branch are monitored in real time by the flow distribution control system. The regulating valves on the hydrogen branch of the premixing system are adjusted to control the hydrogen flow rate at the set value, ensuring that the target hydrogen concentration after natural gas blending is stable. .

[0017] Compared with the prior art, the advantages of the preferred technical solution of the present invention include:

[0018] 1. This invention adopts a two-stage mixing structure of "premixing + final mixing". The premixing system uses the pressure difference between hydrogen and natural gas through an ejector to achieve preliminary mixing, ensuring that hydrogen and natural gas first form a premixed gas with high uniformity. The final mixing system creates artificial turbulence through a reasonable pipeline layout, without relying on the flow rate of the main natural gas pipeline. Even at low flow rates, it can achieve sufficient mixing, and the mixing length is greatly shortened (the mixing length in the embodiment is only 4.8 meters). Compared with the existing T-tube mixing technology, the mixing efficiency is significantly improved, while avoiding the structural complexity of built-in static mixers.

[0019] 2. The premixing system of this invention adopts a combination structure of multiple branch pipelines and premixing units, and the final mixing system adopts multiple small hydrogen-blending pipelines arranged around the main natural gas pipeline. All pipelines and equipment are small in size, eliminating the need for complex mechanical structures inside the main natural gas pipeline. Installation, disassembly and subsequent maintenance are convenient. It is not only suitable for small-diameter natural gas pipelines, but also adaptable to large-diameter long-distance natural gas pipelines, reducing the engineering cost and maintenance difficulty of hydrogen blending in large-diameter natural gas pipelines.

[0020] 3. This invention incorporates a flow distribution control system. By setting premixing ratio coefficients, hydrogen target concentration ratio coefficients, and flow coefficients, it establishes a correlation between the design flow rate of the hydrogen-blended pipeline and the parameters of the main natural gas pipeline. Combined with closed-loop control of the flow meter and regulating valve, it adjusts the hydrogen supply in real time, even when the natural gas processing volume fluctuates significantly (200,000 cubic meters per second). Up to 2 million Even under these conditions, it can ensure that the hydrogen concentration remains stable within the target range with minimal fluctuations, thus meeting the requirements for final combustion and emissions.

[0021] 4. This invention utilizes the characteristic that hydrogen pressure is much higher than natural gas pressure to actively draw in natural gas through an ejector, eliminating the need for additional power equipment and reducing energy consumption. At the same time, by calculating the ejector coefficient and matching the ejector and flow control parameters, the premixing ratio is ensured to be accurate, laying the foundation for uniform mixing in the subsequent final mixing stage and further improving the overall hydrogen doping uniformity. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a natural gas uniform hydrogen blending device according to Example 1.

[0023] Figure 2 This is a schematic diagram of the internal structure of the w-th premixed unit in Embodiment 1.

[0024] Figure 3 This is a schematic diagram of the final mixing system in Example 1.

[0025] Figure 4 This is a schematic diagram of the premixed system in Example 3.

[0026] Figure 5 This is a schematic diagram of the final mixing system in Example 3.

[0027] Figure 6 This is a schematic diagram of a hydrogen concentration monitoring unit installed on a natural gas main pipeline.

[0028] Figure 7 This is a statistical table (%) of the expected hydrogen co-doping concentration of 15% under various natural gas processing volumes.

[0029] Figure 8This is a statistical table (%) of the analytical concentration of 10% hydrogen co-doping at various natural gas processing volumes.

[0030] Figure 9 This is a statistical table (%) of the expected hydrogen co-doping concentration of 20% under various natural gas processing volumes. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] Example 1

[0033] This embodiment provides a natural gas uniform hydrogen blending device (hereinafter referred to as a hydrogen blending device), such as Figures 1-3 As shown, in a preferred embodiment, the hydrogen blending device includes a premixing system, a final mixing system, and a flow distribution control system, which work together to achieve uniform hydrogen blending of natural gas and hydrogen and precise concentration control.

[0034] The premixing system is connected to both the main natural gas pipeline and the hydrogen pipeline to achieve preliminary mixing of natural gas and hydrogen, forming a premixed gas. The premixing system comprises m premixing units, with m branch pipelines branching off from the main natural gas pipeline and m branch pipelines branching off from the hydrogen pipeline. The w-th branch pipeline of the natural gas and the w-th branch pipeline of the hydrogen participating in the premixing are connected one-to-one to the w-th premixing unit, where 1 ≤ w ≤ m, and m is a positive integer. This ensures a one-to-one premixing match and guarantees a consistent mixing ratio in each premixing unit.

[0035] The w-th premixing unit is equipped with Root natural gas branch pipe and root hydrogen branch pipe, The number of natural gas branch pipes in different premixing units may be the same, not exactly the same, or completely different. Preferably, the number is the same, so the number of natural gas branch pipes in each premixing unit is uniformly set to n. Each hydrogen branch pipe is equipped with an ejector (Jw1, Jw2…Jwn). The inlet end of the natural gas branch pipe is connected to the natural gas branch pipe corresponding to the premixing unit. The inlet end of each hydrogen branch pipe is connected to the corresponding hydrogen branch pipe of the premixing unit, and each hydrogen branch pipe is paired with a natural gas branch pipe to achieve precise premixing. The outlet ends of the hydrogen branch pipes and the corresponding natural gas branch pipes are connected to the main inlet and ejector end of the corresponding ejector, respectively. The mixed gas output end of the ejector is connected to the reference hydrogen pipe to output the premixed gas after mixing by the ejector to the final mixing system. Since the hydrogen pressure is much higher than the pressure of the natural gas participating in the premixing, each hydrogen branch pipe can eject the natural gas from each natural gas branch pipe into the ejector, thereby completing the premixing and forming a premixed gas. No additional power equipment is required, reducing energy consumption while improving the uniformity of premixing.

[0036] The final mixing system is connected to the output of the premixing system and then to the main natural gas pipeline. It is used to perform secondary mixing of the premixed gas with the natural gas in the main pipeline, forming a uniform hydrogen-infused natural gas flow. Each of the m premixing units in the premixing system outputs a set of premixed gas pipelines. All premixed gas pipelines are connected to the final mixing system. Each set of premixed gas pipelines contains n hydrogen-infused pipelines, meaning the premixing system outputs m × n hydrogen-infused pipelines. These hydrogen-infused pipelines are arranged around the center of the main natural gas pipeline, and the pipelines at the same location and their installation arrangement are equivalent between sets of premixed gas pipelines. The final mixing system, by arranging the m sets of premixed gas pipelines circumferentially along the main natural gas pipeline, with the outlet direction of the hydrogen-infused pipeline in each set perpendicular to the axis of the main natural gas pipeline, injects the premixed gas into the main natural gas flow in the pipeline in the form of a high-speed jet. This creates localized shear flow and turbulent mixing effects (i.e., artificial turbulence), achieving secondary uniform mixing.

[0037] Specifically, the outlet ends of m sets of premixed gas pipelines output from m premixing units are circumferentially evenly distributed outside the main natural gas pipeline, and the outlet ends of each set of premixed gas pipelines are... The hydrogen-blending pipelines are arranged in parallel and at equal intervals, with the outlet end of the first hydrogen-blending pipeline in each group of premixed gas pipelines tangent to the outer wall of the main natural gas pipeline. For example... Figure 3 As shown, for example, when m is 4, there are 4 groups of premixed gas pipelines. The w-th group contains n hydrogen-doped pipelines, denoted as Pw1, Pw2, ..., Pwn, surrounding the center of the main natural gas pipeline. This layout can create artificial turbulence without adding a static mixer inside the pipeline, ensuring thorough mixing of the premixed gas and natural gas even when changes in operating conditions lead to lower flow velocities within the main natural gas pipeline.

[0038] The flow distribution control system is connected to the premixing system and is used to adjust and control the hydrogen supply to the hydrogen branch pipes according to the operating parameters of the main natural gas pipeline, so as to stabilize the hydrogen blending concentration in the main natural gas pipeline within a preset target range. Specifically, the flow distribution control system includes a flow meter and a regulating valve installed upstream of the ejector on each hydrogen branch pipe. Each hydrogen branch pipe is sequentially equipped with a flow meter (FIw01, FIw02...FIw0n), a regulating valve (Vw1, Vw2...Vwn), and an ejector (Jw1, Jw2...Jwn). The flow meter is used to monitor the hydrogen flow rate in the hydrogen branch pipe in real time and transmit the flow signal to the controller. The regulating valve is used to receive the adjustment command from the controller and change the flow cross-sectional area of ​​the hydrogen branch pipe by adjusting the opening of the regulating valve, so as to adjust the hydrogen supply and control the hydrogen flow rate within the set value. This enables closed-loop control of hydrogen doping concentration.

[0039] like Figure 6 As shown, in another preferred embodiment, a hydrogen concentration monitoring unit is also provided on the natural gas main pipeline downstream of the final mixing system. For example, the hydrogen concentration monitoring unit is located 4.8 meters downstream of the final mixing system. The hydrogen concentration monitoring unit includes several hydrogen concentration analyzers (A1, A2...A9) with their probes inserted into the natural gas main pipeline, which are used to detect whether the hydrogen concentration of the natural gas after hydrogen blending reaches the expected concentration.

[0040] Example 2

[0041] This embodiment provides a method for uniformly blending hydrogen into natural gas, based on the natural gas uniform hydrogen blending device of Embodiment 1, and includes the following steps:

[0042] S1, Parameter Settings

[0043] Obtain the radius of the main natural gas pipeline Natural gas processing capacity Preset premixed hydrogen concentration and the target hydrogen concentration after blending natural gas with hydrogen ; Calculate the premixing ratio coefficient Hydrogen target concentration ratio coefficient and hydrogen-doped pipelines Flow coefficient , specifically:

[0044] Premixing ratio coefficient The following formula is used to obtain it:

[0045]

[0046] in, The preferred value is the premixed hydrogen concentration. The value is 50%.

[0047] Hydrogen target concentration ratio coefficient The following formula is used to obtain it:

[0048]

[0049] in, The preferred value is the benchmark value for the target hydrogen concentration. The value is 10%.

[0050] Flow coefficient It is a hydrogen-doped pipeline radius and hydrogen-doped pipelines Distance to the center of the main natural gas pipeline The bivariate function is obtained based on fluid dynamics simulation fitting. Specific flow coefficients... It is expressed by the following formula:

[0051] Specifically:

[0052]

[0053] in, For group w The serial number of the hydrogen-doped pipeline. For hydrogen-doped pipelines The flow coefficient, For hydrogen-doped pipelines radius, For hydrogen-doped pipelines The distance to the center of the main natural gas pipeline, w=1,2,……,m; n=1,2,……, In a preferred embodiment, since the pipes and their installation arrangement at the same location between premixed gas pipe groups are equivalent, they can also be used. Indicates hydrogen-doped pipeline Distance to the center of the main natural gas pipeline.

[0054] The coefficient of the first-order term of the radius, The coefficient of the first-order distance term. The coefficient of the quadratic term of the radius, The coefficient of the quadratic distance term. S and S are the cross-coupling coefficients. The base offset is a constant term.

[0055] , , , , and These are the undetermined coefficients of the polynomial indexed by w and n, which can be obtained through experimental fitting. Specifically, they are determined first based on the values ​​of w and n. The shape of the function was determined, and then a hydrogen-doped pipeline experimental platform was built to change the radius. and distance The actual flow rate of the hydrogen-doped pipeline was measured, and the values ​​of a, b, c, d, e, and f that best fit the experimental data were calculated using the least squares method or regression analysis.

[0056] Based on the parameters obtained above, based on the hydrogen-doped pipeline The design flow rate determines the flow control setpoint for the nth hydrogen branch in group w. and the selected ejector The gravitation coefficient n=1,2,……, The specific method is as follows:

[0057] Determine the hydrogen-doped pipeline Design flow :

[0058]

[0059] Determine the flow control setpoint for the nth hydrogen branch in group w. :

[0060]

[0061] Determine the ejector to be used for the nth hydrogen branch in group w. The gravitation coefficient :

[0062]

[0063] in, Let n be the sequence number of the nth hydrogen-doped pipe in group w. For natural gas processing volume, For hydrogen-doped pipelines The flow coefficient, Where is the radius of the main natural gas pipeline. For hydrogen-doped pipelines radius, For hydrogen-doped pipelines Distance to the center of the main natural gas pipeline This is the proportionality coefficient for the target hydrogen concentration. This is the premixing ratio coefficient. The preset premixed hydrogen concentration.

[0064] The ejector coefficient = ejector flow rate / mainstream flow rate, where the ejector flow rate is the premixed natural gas flow rate, and the mainstream flow rate is the hydrogen flow rate. The appropriate ejector for the nth hydrogen branch in group w is determined through calculation. The gravitation coefficient When selecting an ejector, it is necessary to choose an ejector with an ejection coefficient close to this.

[0065] S2, Premixing Stage

[0066] Connect m groups of branch pipes from the main natural gas pipeline to m premixing units of the premixing system, and connect m groups of branch pipes from the hydrogen pipeline to their respective premixing units. Start the flow distribution control system to initially mix natural gas and hydrogen according to a preset ratio (i.e., premixed hydrogen concentration) using the premixing system. Utilize the pressure difference between hydrogen and natural gas to draw in natural gas through an ejector. Adjust the regulating valve of the nth hydrogen branch pipe in the wth group to control the flow rate of the nth hydrogen branch pipe to the set value. The premixing process is completed to form a premixed gas, and the concentration of premixed hydrogen in the premixed gas is stabilized at [value missing]. ;

[0067] At the same time, according to the gravitational coefficient Select ejector This ensures that the ejection effect matches the flow rate and guarantees premixing uniformity.

[0068] S3, Final Mixing Stage

[0069] The premixed gas output from the premixing system is passed through the final mixing system. Specifically, the premixed gas pipelines output from m premixing units (i.e., m×n hydrogen-doped pipelines) are connected to the main natural gas pipeline. The pipeline layout of the final mixing system creates artificial turbulence, causing the premixed gas to mix violently with the natural gas in the main natural gas pipeline, achieving secondary uniform mixing and ultimately completing the uniform hydrogen doping of the natural gas.

[0070] S4. Concentration Control and Detection

[0071] During the premixing and final mixing stages, the flow parameters of each hydrogen branch are monitored in real time by the flow meter of the flow distribution control system, and the flow data is transmitted to the controller. The controller compares the actual flow with the set value. The opening of the regulating valve on the hydrogen branch pipe of the premixing system is adjusted in real time to control the hydrogen flow rate within the set value. This ensures a stable hydrogen concentration, thereby guaranteeing that the target hydrogen concentration after blending natural gas remains stable at [specific level]. ;

[0072] By arranging hydrogen concentration monitoring units at a certain distance downstream of the final mixing system, specifically by uniformly arranging multiple hydrogen concentration analyzers, the hydrogen concentration of the natural gas after hydrogen blending is detected in real time, forming a closed-loop control.

[0073] Example 3

[0074] like Figure 4 As shown, this embodiment uses a premixed system with two sets of hydrogen pipelines, each set having one hydrogen branch pipe, i.e., m=2, n=1, for illustration. Correspondingly, as... Figure 5 As shown, the final mixing system has two sets of premixed gas pipelines, each with one hydrogen-blending pipeline, namely hydrogen-blending pipelines P11 and P21, which are located at the upper and lower parts of the main natural gas pipeline, respectively, and are tangent to the pipe wall of the main natural gas pipeline.

[0075] radius of the main natural gas pipeline It is 0.6 meters. Natural gas processing capacity. 2,000,000 That is, 2 million .

[0076] The distance L11 from hydrogen-blended pipeline P11 to the center of the main natural gas pipeline is 0.6 meters, and the distance L21 from hydrogen-blended pipeline P21 to the center of the main natural gas pipeline is also 0.6 meters. The radius R11 of hydrogen-blended pipeline P11 is 0.125 meters, and the radius R21 of hydrogen-blended pipeline P21 is also 0.125 meters. Since the pipelines at the same location and their installation arrangement are equivalent between premixed gas pipeline groups, the distances from hydrogen-blended pipelines P11 and P21 to the center of the main natural gas pipeline are both represented by L1.

[0077] The premixed hydrogen concentration Cyu is 40%, and the target hydrogen concentration Ch after blending natural gas is 15% (i.e., the hydrogen blending concentration is 15%).

[0078] The premixing ratio coefficient Kyu = Cyu / 0.5 = 0.8, and the hydrogen target concentration ratio coefficient after natural gas blending with hydrogen Kh = Ch / 0.1 = 1.5.

[0079] When m=2 and n=1, the relationship between the flow coefficients K11 and K21 of the hydrogen-infused pipeline and the radii R11 / R21 of the hydrogen-infused pipelines P11 and P21 and their distance from the center of the main natural gas pipeline L1 is designed as follows:

[0080] K11=0.0047×R11+0.0001×L1-0.0193× +0× +0.1875×R11×L1-0.0002;

[0081] K21=0.0047×R21+0.0001×L1-0.0193× +0× +0.1875×R21×L1-0.0002;

[0082] K11=K21=0.014208.

[0083] The design flow rates of hydrogen-doped pipelines P11 and P21 are F11 or F21 = 2000000 × 0.014208 × 0.6 / 0.125 / 0.6 × 1.5 / 0.8 = 426253 .

[0084] In the premixed system, the flow control setpoint on the first hydrogen branch of the first group is SP11. SP11 = F11 × Cyu = 426253 × 0.4 = 170501 .

[0085] In the premixed system, the flow control setpoint on the first hydrogen branch of the second group is SP21. SP21 = F21 × Cyu = 426253 × 0.4 = 170501 .

[0086] In the premixing system, the ejector J11 selected on the first hydrogen branch of the first group has an ejection coefficient of... =[F11×(1-Cyu)] / SP11=426253×(1-0.4) / 170501≈1.5.

[0087] In the premixing system, the ejector J21 selected on the first hydrogen branch of the second group has an ejection coefficient of... =[F21×(1-Cyu)] / SP21=426253×(1-0.4) / 170501≈1.5.

[0088] In the premixing system, on the first hydrogen branch of the first group, a regulating valve V11 is used to control the flow meter FI101 to the set value of 170501. .

[0089] In the premixing system, on the first hydrogen branch of the second group, a regulating valve V21 is used to control the flow meter FI201 to the set value of 170501. .

[0090] like Figure 6 As shown, several hydrogen concentration analyzers (A1, A2...A9) are inserted into the main natural gas pipeline 4.8 meters downstream of the final mixing system to detect whether the expected concentration is uniformly achieved.

[0091] The foregoing describes the natural gas processing capacity using this invention. For 2 million An example with a hydrogen blending concentration of 15% is given. Using the same method, the natural gas processing volume and hydrogen blending concentration are varied, and the hydrogen concentration of the blended natural gas is monitored in real time using hydrogen concentration analyzers (A1, A2…A9). The detection results are as follows: Figure 7-9 As shown.

[0092] The test results show that, after adopting this invention, when the natural gas processing capacity is 200,000 cubic meters per second... Up to 2 million When the concentration fluctuates between 10%, 15%, and 20%, the actual detected concentration fluctuates slightly around the expected concentration, with small fluctuation amplitude and good mixing uniformity. Furthermore, the mixing length of the natural gas hydrogen blending example of this invention is only 4.8 meters, significantly shorter than existing technologies. Compared to a DN1200 (0.6-meter radius) natural gas main pipeline, the mixing length is small, fully meeting the mixing distance requirements for industrial hydrogen blending. Moreover, the pipelines and equipment configured in this invention are relatively small in size, facilitating installation and maintenance.

[0093] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A device for uniformly blending hydrogen into natural gas, characterized in that, Including premixing systems and final mixing systems; The premixing system is connected to the main natural gas pipeline and the hydrogen pipeline respectively, and is used to achieve the initial mixing of natural gas and hydrogen to form premixed gas. The premixing system includes m premixing units, m sets of branch pipelines from the main natural gas pipeline and m sets of branch pipelines from the hydrogen pipeline. The w-th branch pipeline of natural gas and the w-th branch pipeline of hydrogen participating in the premixing are connected to the w-th premixing unit in a one-to-one correspondence, where 1≤w≤m and m is a positive integer. The w-th premixing unit is equipped with Root natural gas branch pipe and Each hydrogen gas branch pipe has an ejector installed. The inlet end of the natural gas branch pipe is connected to the natural gas branch pipe corresponding to the premixing unit. The inlet end of each hydrogen branch pipe is connected to the hydrogen branch pipe corresponding to the premixing unit, and each hydrogen branch pipe is matched with a natural gas branch pipe. The value is a positive integer; the outlet end of the hydrogen branch pipe and the outlet end of the corresponding natural gas branch pipe are respectively connected to the main inlet and the ejector end of the corresponding ejector; the mixed gas output end of the ejector is connected to the hydrogen mixing pipeline, which is used to output the premixed gas after being mixed by the ejector to the final mixing system. The input end of the final mixing system is connected to the output end of the premixing system, and the output end of the final mixing system is connected to the main natural gas pipeline. It is used to perform secondary mixing of the premixed gas and the natural gas in the main natural gas pipeline to form a uniform hydrogen-doped natural gas flow.

2. The natural gas uniform hydrogen blending device according to claim 1, characterized in that, The premixing system has m premixing units, each outputting a set of premixed gas pipelines. All premixed gas pipelines are connected to the final mixing system. Each set of premixed gas pipelines is equipped with... The hydrogen-blending pipeline is arranged around the center of the main natural gas pipeline, and the pipelines at the same position and the installation arrangement between the premixed gas pipeline groups are equivalent.

3. A natural gas uniform hydrogen blending device according to claim 2, characterized in that, The outlet ends of the m premixed gas pipelines output by the m premixed units are evenly distributed circumferentially outside the main natural gas pipeline, and the outlet ends of each premixed gas pipeline are... The hydrogen-blending pipelines are arranged in parallel and at equal intervals, and the outlet end of the first hydrogen-blending pipeline in each group of premixed gas pipelines is tangent to the outer wall of the main natural gas pipeline.

4. A natural gas uniform hydrogen blending device according to claim 1, characterized in that, A hydrogen concentration monitoring unit is also installed on the main natural gas pipeline downstream of the final mixing system. The hydrogen concentration monitoring unit includes several hydrogen concentration analyzers with their probes inserted into the main natural gas pipeline.

5. A natural gas uniform hydrogen blending device according to claim 1, characterized in that, The number of natural gas branch pipes installed in different premixed units may be the same, not exactly the same, or completely different.

6. A natural gas uniform hydrogen blending device according to any one of claims 1-5, characterized in that, It also includes a flow distribution control system connected to the premixing system, which is used to adjust and control the hydrogen supply of the hydrogen branch pipe according to the operating parameters of the natural gas main pipeline, so as to keep the hydrogen concentration in the natural gas main pipeline stable within a preset target range. The flow distribution control system includes a flow meter and a regulating valve installed on each of the hydrogen branch pipes upstream of the ejector. The flow meter is used to monitor the hydrogen flow rate in the hydrogen branch pipe in real time and transmit the flow signal to the controller; The regulating valve is used to receive the regulating command from the controller and change the flow cross-sectional area of ​​the hydrogen branch pipe to regulate the hydrogen supply.

7. A method for uniformly blending hydrogen into natural gas, characterized in that, The method based on the natural gas uniform hydrogen blending device according to any one of claims 1-6 includes the following steps: S1. Obtain the radius of the main natural gas pipeline. Natural gas processing capacity Premixed hydrogen concentration And set the target hydrogen concentration after blending natural gas with hydrogen. ; Calculate the premix ratio coefficient Hydrogen target concentration ratio coefficient and hydrogen-doped pipelines Flow coefficient ; Based on the parameters obtained above, based on the hydrogen-doped pipeline The design flow rate determines the flow control setpoint for the nth hydrogen branch in group w. and the selected ejector The gravitation coefficient n=1,2,……, ; S2. Natural gas and hydrogen are initially mixed in a preset ratio using a premixing system. Utilizing the pressure difference between hydrogen and natural gas, natural gas is drawn in through an ejector. The flow rate of the nth hydrogen branch in group w is controlled to the set value by adjusting the regulating valve. Premixing is completed, forming a premixed gas; S3. The premixed gas output from the premixing system is sent into the natural gas main pipeline through the final mixing system. The pipeline layout of the final mixing system creates artificial turbulence to achieve uniform mixing of the premixed gas and the natural gas in the natural gas main pipeline. S4. In steps S2 and S3, the flow parameters of each hydrogen branch are monitored in real time by the flow distribution control system, and the regulating valves on the hydrogen branch of the premixing system are adjusted to control the hydrogen flow rate within the set value. To ensure that the target hydrogen concentration remains stable after blending natural gas with hydrogen. .

8. The hydrogen doping method according to claim 7, characterized in that, In step S1, Premixing ratio coefficient The following formula is used to obtain it: in, This serves as a baseline value for the premixed hydrogen concentration; Hydrogen target concentration ratio coefficient The following formula is used to obtain it: in, This serves as a baseline value for the target hydrogen concentration. Flow coefficient It is a hydrogen-doped pipeline radius and hydrogen-doped pipelines Distance to the center of the main natural gas pipeline A bivariate function, flow coefficient It is expressed by the following formula: in, For group w The serial number of the hydrogen-doped pipeline. For hydrogen-doped pipelines The flow coefficient, For hydrogen-doped pipelines radius, For hydrogen-doped pipelines Distance to the center of the main natural gas pipeline, w=1,2,……,m; n=1,2,……, ; The coefficient of the first-order term of the radius, The coefficient of the first-order distance term. The coefficient of the quadratic term of the radius, The coefficient of the quadratic distance term. S and S are the cross-coupling coefficients. The base offset is a constant term.

9. The hydrogen doping method according to claim 7, characterized in that, Based on the parameters obtained in step S1, determine the w-th group and the first... Flow control setpoint for the root hydrogen branch and the selected ejector The gravitation coefficient The specific method is as follows: Determine the hydrogen-doped pipeline Design flow : Determine the flow control setpoint for the nth hydrogen branch in group w. : Determine the ejector to be used for the nth hydrogen branch in group w. The gravitation coefficient : in, For group w The serial number of the hydrogen-doped pipeline. For natural gas processing volume, For hydrogen-doped pipelines The flow coefficient, Where is the radius of the main natural gas pipeline. For hydrogen-doped pipelines radius, For hydrogen-doped pipelines Distance to the center of the main natural gas pipeline This is the proportionality coefficient for the target hydrogen concentration. This is the premixing ratio coefficient. The preset premixed hydrogen concentration.

10. The hydrogen doping method according to claim 7, characterized in that, In step S2, the concentration of premixed hydrogen in the premixed gas is stabilized at... In step S4, a hydrogen concentration monitoring unit is installed downstream of the final mixing system to detect the hydrogen concentration of the natural gas after hydrogen blending in real time, thus forming a closed-loop control.

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