A helical structure hydrogen blending combustion system

Abstract

This invention relates to a spiral-structured hydrogen blending combustion system, comprising a burner, a fuel passage, and an air passage. A vertical pipe is used for hydrogen input, and a horizontal pipe is used for hydrogen output, allowing hydrogen to be blended with natural gas. The horizontal pipe extends in the direction of natural gas flow, and rotating turbulence-inducing blades are arranged on the outer wall of the horizontal pipe. Hydrogen outlet holes are provided between the rotating turbulence-inducing blades. In this invention, hydrogen enters from the front with the blade structure, flowing perpendicular to the natural gas to initially turbulently mix it. After the hydrogen is drawn out at the inlet of the blade passage and mixed with the natural gas, the rotating blade structure causes the mixed gas to change its flow direction as it flows within, forming vortices to enhance turbulence and mixing. Natural gas is then allowed to enter the flow channel formed by the blades, further enhancing the turbulence effect and strengthening the hydrogen blending.

Description

Technical Field

[0001] This invention relates to the field of combustion technology, and more specifically to a combustion system for a mixture of hydrogen and gas fuel. Background Technology

[0002] Hydrogen is a relatively popular green renewable energy source with advantages such as high calorific value per unit mass and easy and complete combustion. However, there are certain drawbacks when hydrogen is directly used in industrial fuel combustion, such as high cost, high local combustion temperature, easy generation of large amounts of H2O, and low safety performance.

[0003] To address global climate change and achieve carbon emission reduction goals, renewable energy sources such as wind, solar, and hydropower have developed rapidly. The main problem with renewable energy is its volatility, and its rapid growth poses a serious threat to grid security. To ensure grid security, surplus electricity cannot be connected to the grid, leading to severe curtailment of wind, solar, and hydropower. Meanwhile, hydrogen is an excellent energy carrier, so we can convert and store fluctuating renewable energy sources. However, due to the high cost of large-scale hydrogen storage, the immaturity of hydrogen fuel cell technology, and the lack of adequate hydrogen infrastructure, the utilization of pure hydrogen will take a considerable amount of time. Therefore, blending a certain proportion of hydrogen with natural gas for combustion in gas turbines is a better solution for the transition from fossil fuels to hydrogen energy. However, because hydrogen has an extremely high flame propagation speed, it is highly susceptible to backfire, and existing natural gas burners cannot achieve a high proportion of hydrogen blending with natural gas.

[0004] The prior art CN111911961A discloses a natural gas high-proportion hydrogen co-firing burner, including a combustion chamber equipped with a fan. The combustion chamber contains a primary burner located at the center and a secondary burner located around the periphery of the primary burner. The primary burner includes a primary burner nozzle located at the center and double swirl blades arranged around the periphery of the primary burner nozzle. The secondary burner includes several secondary burner nozzles arranged in a ring around the periphery of the double swirl blades. Each secondary burner nozzle has a Venturi converging nozzle at its nozzle opening. The primary burner nozzles are connected to a primary fuel line, and each secondary burner nozzle is connected to a secondary fuel line, achieving a two-stage combustion organization of primary combustion at the center and secondary combustion around the periphery. This invention achieves high-proportion hydrogen co-firing of natural gas through the combination of two-stage combustion and rational combustion organization, effectively preventing backfire and flameout. Furthermore, it enables rapid mixing of fuel gas and air, ensuring complete combustion, improving efficiency, and reducing emissions.

[0005] CN115479272A discloses a hydrogen-natural gas co-firing burner, including a burner body, a natural gas pipe, and a hydrogen pipe. A combustion-supporting gas is introduced into the burner body. A cyclone vane is provided at the end of the burner body, with combustion-supporting air holes communicating with the inner cavity of the burner body. A boss is provided at the center of the cyclone vane, which is hollow and has a hydrogen nozzle. The height of the hydrogen nozzle is less than the height of the boss. Natural gas nozzles are provided on the top, outer, and inner sides of the boss. The natural gas pipe is located inside the burner body and its end is connected to the natural gas nozzle. The hydrogen pipe is sleeved inside the natural gas pipe and its end is connected to the hydrogen nozzle. This burner co-fires hydrogen and natural gas as fuel, effectively utilizing the advantages of hydrogen while overcoming its disadvantages when burned alone.

[0006] Before utilizing both, hydrogen and natural gas need to be blended. However, the extremely low density of hydrogen compared to natural gas makes uniform mixing difficult, and the required pipeline distance for uniform mixing is long, which can lead to hydrogen embrittlement of metal materials and other safety issues. If blending occurs before gas equipment, it also needs to be done as quickly as possible before entering the equipment to ensure safe utilization. Therefore, whether using hydrogen for natural gas pipeline transportation or for the combined use of both, it is necessary to adopt technical means to achieve uniform blending of hydrogen and natural gas within the shortest possible pipeline distance. Furthermore, because hydrogen and natural gas cannot be fully mixed, combustion efficiency is low, combustion is incomplete, and excessive local hydrogen can lead to deflagration.

[0007] Therefore, based on the above problems, a new combustion system is needed that can improve combustion efficiency, reduce carbon monoxide emissions, and avoid danger by fully mixing hydrogen and natural gas. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a combustion system for a mixture of hydrogen and gas fuel, thereby improving combustion efficiency.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A spiral-structured hydrogen blending combustion system includes a burner, a fuel passage, and an air passage. Air is introduced through an air inlet and distributed to the burner via the air passage. A blended fuel of natural gas and hydrogen is introduced through the fuel passage, fully mixed with the air, and then enters the burner for combustion. The fuel passage includes a natural gas pipeline and a hydrogen pipeline. The hydrogen pipeline is inserted into the natural gas pipeline. The hydrogen pipeline includes a vertical section perpendicular to the natural gas pipeline and a horizontal pipe parallel to the natural gas pipeline. The horizontal pipe connects to the vertical section. The vertical pipe is used for hydrogen input, and the horizontal pipe is used for hydrogen output, thus mixing hydrogen with natural gas. The horizontal pipe extends in the direction of natural gas flow. Rotating baffles are provided on the outer wall of the horizontal pipe, and hydrogen outlet holes are provided between the rotating baffles.

[0011] As an improvement, the front end of the horizontal pipe is equipped with a semi-ellipsoidal structure facing the direction of natural gas flow.

[0012] As an improvement, the height of the turbulence blades extending outward from the outer wall of the horizontal pipe is continuously increased along the flow direction of natural gas.

[0013] As an improvement, the height and amplitude of the turbulence blades extending outward from the outer wall of the horizontal pipe are continuously increased along the flow direction of natural gas.

[0014] As an improvement, the number of hydrogen outlet holes is continuously reduced along the flow direction of natural gas.

[0015] As an improvement, the number of hydrogen outlet holes is continuously increased and the rate of increase is continuously decreased along the direction of natural gas flow.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] In this structure, hydrogen enters from the front with blades, flowing perpendicular to the natural gas to initially turbulent and mix it. After mixing with the natural gas at the inlet of the blade channel, the rotating blades cause the mixed gas to change its flow direction, forming vortices and enhancing turbulence and mixing. Natural gas is then allowed to enter the flow channel formed by the blades, further enhancing the turbulence and hydrogen mixing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0019] Figure 2 This is a three-dimensional view of the rotating blade mixing and turbulence structure of the present invention;

[0020] Figure 3 This is a schematic diagram of an assembly of a natural gas-hydrogen blending device with rotating blades of the present invention placed inside a pipeline.

[0021] Figure 4 This is an internal cross-sectional view of a natural gas-hydrogen blending device with rotating blades of the present invention placed inside a pipeline.

[0022] Figure 5 This is a perspective view of the rotating blade natural gas-hydrogen blending device of the present invention placed inside a pipeline;

[0023] Figure 6 This is a dimensional diagram of the rotating blade mixing and turbulence structure of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1-5 The hybrid combustion system of the present invention is demonstrated. For example... Figure 1 As shown, a combustion system is provided in which air is introduced through an air inlet and distributed to the inside of the burner through an air passage 3. A blend of natural gas and hydrogen fuel is introduced through a fuel passage 4, and after being fully mixed with the air, it enters the burner for combustion.

[0026] like Figure 3 As shown, the fuel channel includes a natural gas pipeline 1 and a hydrogen pipeline 2. The hydrogen pipeline 2 is inserted into the natural gas pipeline 1. The hydrogen pipeline 2 includes a vertical pipe 21 perpendicular to the natural gas pipeline and a horizontal pipe 22 disposed in the natural gas pipeline parallel to the natural gas pipeline. The horizontal pipe 22 is connected to the vertical pipe 21. The vertical pipe 21 is used to input hydrogen, and the horizontal pipe is used to output hydrogen, so that hydrogen is mixed in the natural gas. The horizontal pipe 22 extends in the direction of natural gas flow. Rotating baffles 23 are provided on the outer wall of the horizontal pipe. Hydrogen outlet holes 24 are provided between the rotating baffles in the horizontal pipe.

[0027] In this structure, hydrogen enters from the front with blades, flowing perpendicular to the natural gas to initially turbulent and mix it. After mixing with the natural gas at the inlet of the blade channel, the rotating blades cause the mixed gas to change its flow direction, forming vortices and enhancing turbulence and mixing. Natural gas is then allowed to enter the flow channel formed by the blades, further enhancing the turbulence and hydrogen mixing.

[0028] The main feature of this invention is that it consists of a cylindrical structure parallel to the natural gas flow direction plus rotating turbulence blades. Hydrogen enters the rear end of the cylinder through a hydrogen inlet pipe perpendicular to the natural gas pipeline, and hydrogen is drawn out through a hole on the surface of the cylinder at the inlet of the blade flow channel.

[0029] As an improvement, the cylinder diameter and the shape and size of the blades can be changed according to the flow rates of natural gas and hydrogen. When the flow rate is fixed, as the natural gas flow rate increases, the diameter of the natural gas transmission pipe will increase. While maintaining the hydrogen transmission ratio, the hydrogen gas flow rate will also increase, thus requiring a larger hydrogen transmission pipe. To maintain a good mixing effect and make the natural gas and hydrogen mix more uniformly, the cylinder diameter will be increased. To maintain a good turbulence effect, the blade pitch S and blade height will be increased, so that the blade height and cylinder diameter, and the pitch and cylinder diameter, are consistent. Therefore, h / d1 = 1 / 3 and s / d1 = 5 / 1 are preferred to maintain good turbulence and good mixing effects.

[0030] As an improvement, a semi-ellipsoidal structure 25 is positioned at the front end of the horizontal pipe, facing the direction of the natural gas flow. When the gas flow encounters the semi-ellipsoidal structure, the sharp edges can generate strong shear stress in the fluid, making it easier to induce local eddies and turbulence. These turbulences disrupt the laminar flow stability, increase flow instability, and promote gas mixing. This effectively converts the fluid's kinetic energy into turbulent energy. Turbulence has a higher kinetic energy dispersion and mixing effect, thus helping to improve the mixing efficiency of the entire flow field. The semi-ellipsoidal structure can also effectively reduce dead zones and flow separation in the fluid. Flow separation can lead to slow or stagnant local flow, affecting the uniformity of mixing. The sharp edges maintain flow continuity and avoid these adverse phenomena. Preferably, the ratio of major axis a: minor axis b: focal point c is 85:36:77. This selection achieves the best flow effect.

[0031] As an improvement, the height of the turbulence blades extending outward from the outer wall of the horizontal pipe increases continuously along the natural gas flow direction. This configuration allows for thorough mixing of natural gas and hydrogen upstream of the natural gas flow due to the smaller blade height. As the blade height increases, the fully mixed natural gas and hydrogen enter the spiral flow channel, where the rotational force increases, resulting in a greater rotational force in the output gas flow. This, in turn, allows for more thorough swirling mixing of the mixed natural gas and hydrogen with the unmixed natural gas in the secondary mixing zone downstream of the vertical pipe, further improving the uniformity of the mixture.

[0032] As an improvement, the height and amplitude of the turbulence blades extending outward from the outer wall of the horizontal pipe are continuously increased along the flow direction of natural gas. This continuous increase in amplitude further enhances the uniformity of the mixing.

[0033] As an improvement, the number of hydrogen outlet holes decreases continuously along the natural gas flow direction. This variation in the number of hydrogen outlet holes results in a decreasing output of hydrogen along the natural gas flow direction. This design allows hydrogen to be distributed as much as possible at the front end, ensuring thorough mixing with the natural gas. This is especially true when combined with the increasing height of the front-end baffles, which minimize obstruction between the baffles and flow channels, thus guaranteeing sufficient mixing of hydrogen and natural gas at the front. After thorough mixing, the gas enters the higher baffle channels. At this point, the flow rate in the baffle channels is relatively fixed, and the channels are separated, resulting in less mixing. The height of the baffles also ensures sufficient subsequent turbulence force.

[0034] As an improvement, the number of hydrogen outlet holes is continuously reduced and the amplitude is continuously increased along the flow direction of natural gas. This amplitude setting ensures further improvement in mixing efficiency.

[0035] As an improvement, the spoiler blades are elastic structures. They can vibrate elastically during the natural gas flushing process, thereby further increasing the mixing of natural gas and hydrogen.

[0036] As an improvement, the elasticity of the same baffle blade varies at different positions, gradually increasing along the flow direction of natural gas. This is mainly achieved through this setup, combined with the variation in blade height. As natural gas flows between the baffle blades, the flow rates of natural gas and hydrogen remain relatively constant. Natural gas and hydrogen need to be thoroughly mixed, and by continuously increasing the elasticity, the natural gas and hydrogen within the flow channel are ensured to mix completely. This design achieves thorough mixing while also saving costs.

[0037] Preferably, the elasticity of the baffle blades gradually increases along the flow direction of the natural gas. This variation in elasticity is a conclusion drawn from numerous numerical simulations and experiments. This configuration further enhances the thorough mixing of hydrogen and natural gas, achieving a fully mixed effect.

[0038] As an improvement, the horizontal pipes of the natural gas and hydrogen pipelines are arranged coaxially. On the one hand, this arrangement makes the device easier to install and operate, allowing for rapid integration into existing systems and reducing installation time and labor costs. On the other hand, the coaxial arrangement improves the uniformity of the device's spatial distribution within the pipeline, preventing gas from escaping through gaps due to uneven distribution, thus preventing uneven mixing. The coaxial layout ensures that the two gases can fully contact and mix uniformly, achieving a more consistent and efficient mixing effect.

[0039] As an improvement, the hydrogen outlet holes have different distribution densities at their upper and lower positions. Along the horizontal tube, the density decreases from the bottom to the top, resulting in a smaller air output. This is mainly because hydrogen has a low density and therefore flows upwards easily. This design ensures a relatively uniform distribution of hydrogen across the entire circumference of the horizontal hydrogen tube, guaranteeing more thorough and even mixing.

[0040] As an improvement, the rate at which the distribution density decreases gradually increases from the bottom to the top of the horizontal pipe. This setting further ensures more thorough and uniform mixing.

[0041] As an improvement, the diameter of the natural gas inlet pipe is D, the diameter of the hydrogen inlet pipe is d1, and the diameter of the spiral hydrogen outlet pipe is d2. The natural gas flow rate is Q1, and the hydrogen gas flow rate is Q2. The blade height is h, and the blade length is S, where h / d1≈1 / 3 and S / d1≈5 / 1. The flow ratio of hydrogen to fuel gas is 1:9, and d1:D is 1:3. By selecting the blade diameter, height, and length, the fuel gas and hydrogen pipe diameters, and the hydrogen-fuel gas flow ratio, the hydrogen and fuel gas can be fully mixed, achieving the optimal mixing effect.

[0042] When the blade height varies, the average blade height h is taken.

[0043] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A spiral structure hydrogen blending combustion system, comprising a burner, a fuel channel and an air channel, air is introduced by an air inlet, distributed to the inside of the burner through the air channel, and the blending fuel of natural gas and hydrogen is introduced by the fuel channel, fully mixed with air, and then burned in the burner; characterized in that, The fuel passage includes a natural gas pipeline and a hydrogen pipeline. The hydrogen pipeline is inserted into the natural gas pipeline. The hydrogen pipeline includes a vertical pipe perpendicular to the natural gas pipeline and a horizontal pipe arranged in the natural gas pipeline parallel to the natural gas pipeline. The horizontal pipe is connected to the vertical pipe. The vertical pipe is used to input hydrogen, and the horizontal pipe is used to output hydrogen, so that the hydrogen is mixed in the natural gas. The horizontal pipe extends in the direction of natural gas flow. Rotating baffles are provided on the outer wall of the horizontal pipe. Hydrogen outlet holes are provided between the rotating baffles in the horizontal pipe. The front end of the horizontal pipe is equipped with a semi-ellipsoidal structure facing the direction of natural gas flow; along the flow direction of natural gas, the height of the turbulence blades extending outward from the outer wall of the horizontal pipe continuously increases.

2. The combustion system of claim 1, wherein, Along the direction of natural gas flow, the height and amplitude of the turbulence blades extending outward from the outer wall of the horizontal pipe continuously increase.

3. The combustion system of claim 1, wherein, The number of hydrogen outlet holes increases continuously along the direction of natural gas flow.

4. The combustion system of claim 3, wherein, Along the direction of natural gas flow, the number and magnitude of hydrogen extraction holes continuously increase.

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