Swirl duty multi-element micro-mixing coupled low-nitrogen combustion device for hydrogen-doped natural gas

Abstract

The present application relates to clean energy combustion technology, aiming at providing a swirl shift multi-element micro-mixing coupled low-nitrogen combustion device for hydrogen-doped natural gas. It comprises air cooling cavity, air bin fixed cavity and gas bin fixed cavity arranged in sequence from top to bottom; shift combustion unit with sleeve structure in the center; micro-mixing combustion unit, independent air bin and independent gas bin arranged uniformly along the circumference; several micro-mixing injection pipes arranged axially inside the air cooling sleeve of the micro-mixing combustion unit, and fuel injection pipes arranged axially on the second fixed disc; the closed end of the fuel injection pipe extends into the corresponding micro-mixing injection pipe; gas inlet is arranged at the bottom of the gas bin fixed cavity. The present application uses the air flow path from top to bottom to introduce external air to cool the burner head, and then mixes the heated air with fuel for combustion, realizing safe, efficient and low emission application of natural gas with large proportion of hydrogen-doped fuel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of clean energy combustion, and particularly relates to a swirl shift multi-element micro-mixing coupled low-nitrogen combustion device for hydrogen-doped natural gas. BACKGROUND

[0002] With the popularization and practice of the green environmental protection concept, the trend of using clean low-carbon fuel to replace traditional fossil energy combustion gradually highlights. Hydrogen has the advantages of wide source, zero carbon emission, high calorific value and the like, and is a very potential carbon-free alternative fuel in gas turbines, industrial boilers and aero-engine equipment. As a new micro-mixing combustion technology for the development of next-generation high-efficiency low-carbon gas turbines, the fuel used by the micro-mixing combustion is mostly hydrogen-rich or pure hydrogen fuel. Micro-mixing combustion replaces traditional large nozzles with a large number of millimeter-level diameter micro-mixing nozzles with simplified structure, and multi-array micro-channels convert large-scale flames into multiple small flames, effectively suppressing the backfire of hydrogen and uniformly distributing the heat load, which is one of the most promising hydrogen combustion technologies and development directions at present. Due to the high cost of hydrogen production, storage and transportation, hydrogen alone cannot be used as fuel in a wider application field. Therefore, hydrogen is mixed with a large proportion of natural gas (such as natural gas with a mixing volume of more than 30% or even more) to be used as fuel, and a corresponding combustion device is provided, which becomes a research direction in the industry.

[0003] However, due to the great difference in physical and chemical properties and combustion characteristics between hydrogen and natural gas, especially the high reactivity and flame propagation speed of hydrogen, which are much higher than those of natural gas, the backfire risk is high, and there are problems of combustion instability and high thermal NOx emission. This makes it difficult for the existing pure hydrogen or hydrogen-rich micro-mixing burner structure and traditional dry lean premixed low-emission combustion technology to be applicable to hydrogen-doped natural gas fuel with a high proportion of natural gas.

[0004] Therefore, the present application proposes a new scheme to solve the above problems. SUMMARY

[0005] The technical problem solved by the present application is to overcome the deficiencies in the prior art and provide a swirl shift multi-element micro-mixing coupled low-nitrogen combustion device for hydrogen-doped natural gas.

[0006] To solve the technical problem, the solution of the present application is:

[0007] The application discloses a low-nitrogen combustion device for hydrogen-doped natural gas, which comprises an air cooling cavity (1), an air bin fixing cavity (2) and a gas bin fixing cavity (3) arranged in sequence from top to bottom; a sleeve structure duty combustion unit is arranged in the center of the main structure and penetrates the cavities; the duty combustion unit comprises a gas pipe (9) and an air sleeve (10) arranged coaxially; a plurality of installation holes are uniformly arranged on the cavity plates of the main structure and surround the duty combustion unit; an annular partition plate is arranged on the edge of each installation hole in the air bin fixing cavity (2) and the gas bin fixing cavity (3) to form independent air bins (5) and independent gas bins (6) corresponding to the installation holes, thereby forming a plurality of embedded installation positions arranged in a ring shape.

[0008] The device further comprises a plurality of micro-mixed combustion units corresponding to the embedded installation positions, each of which comprises an air cooling sleeve (4) and a second fixing disc (17); a combustion disc and a first fixing disc (16) are arranged at the top and bottom of the air cooling sleeve (4) respectively, each of which has a plurality of through holes arranged in an array and the through holes are corresponding to each other; a plurality of micro-mixed injection pipes (7) are arranged in an array along the axial direction in the air cooling sleeve (4), and the two ends of the micro-mixed injection pipes (7) are inserted into the through holes in the combustion disc and the first fixing disc (16) respectively; a plurality of through holes are arranged in an array along the axial direction on the second fixing disc (17), and a single-end closed fuel injection pipe (8) is inserted into the upper end of each through hole; a plurality of premixed micro-holes (15) are uniformly arranged on the side wall near the closed end of the fuel injection pipe (8); the closed end of the fuel injection pipe (8) extends into the corresponding micro-mixed injection pipe (7) and the premixed micro-holes (15) are not exposed, and sufficient internal space is reserved in the micro-mixed injection pipe (7) for fuel and air mixing; the plurality of micro-mixed combustion units are inserted into the embedded installation positions respectively, the air cooling sleeve (4), the first fixing disc (16) and the second fixing disc (17) are matched with the corresponding installation holes on the cavity plates, and the independent air bins (5) and the independent gas bins (6) are sealed; a gas inlet (13) connected with the independent gas bins (6) is arranged on the bottom cavity plate of the gas bin fixing cavity (3).

[0009] An air inlet (14) is arranged on the side wall of the air cooling cavity (1), the air bin fixing cavity (2) or the gas bin fixing cavity (3), air through holes are arranged on the cavity plates between the corresponding cavities, a plurality of air injection holes (4-1) are arranged on the side wall of the air cooling sleeve (4), disc through holes (16-1) are arranged on the first fixing disc (16), and a gap is kept between the micro-mixed injection pipe (7) and the fuel injection pipe (8); in this way, an air flow path is formed, external air is introduced to cool the head of the burner, and then the heated air is mixed with fuel for combustion.

[0010] As a preferred scheme of the present application, the main body of the gas bin fixing cavity (3) is in a hollow cylindrical structure, and the edges of the upper and lower cavity plates extend transversely to form annular flanges; the air cooling cavity (1) and the air bin fixing cavity (2) are both in a barrel shape with an open bottom, and the edges of the open bottom extend transversely to form annular flanges; the air cooling cavity (1), the air bin fixing cavity (2) and the gas bin fixing cavity (3) are stacked in sequence, and fastening installation is realized by penetrating the through holes on the flanges with bolts.

[0011] As a preferred scheme of the present application, a plurality of circular openings matching the shapes of the micro-mixed combustion units are respectively arranged on the cavity plates of the air cooling cavity (1) and the air bin fixing cavity (2) and the upper cavity plate of the gas bin fixing cavity (3); the micro-mixed combustion units pass through the openings from top to bottom and are seated on the lower cavity plate of the gas bin fixing cavity (3); the gas inlet (13) is a pipe penetrating the lower cavity plate of the gas bin fixing cavity (3).

[0012] As a preferred scheme of the present application, threads are arranged on the edges of the first fixing disc (16) and the second fixing disc (17) in the micro-mixed combustion unit, and matching threads are arranged on the opening holes of the cavity plates corresponding to the two discs; the micro-mixed combustion unit is inserted into the opening holes of the cavity plates downward and is installed in a sealed manner in a spiral way.

[0013] As a preferred scheme of the present application, a cyclone (11) is arranged in the annular area between the gas passage pipe (9) and the air sleeve pipe (10), which is composed of a central sleeve and 8-12 cyclone blades arranged on the sleeve; the inner wall of the sleeve is provided with threads and is installed on the top of the gas passage pipe (9) in a threaded fitting manner, and the outer end surface is flush with the surface of the combustion disc; the axial angle between the cyclone blades and the sleeve ranges from 30° to 45°, and the air jet velocity is 4-6 times that of the gas by setting the annular flow area of the duty combustion unit and the angle of the cyclone blades.

[0014] As a preferred scheme of the present application, the number of the micro-mixed injection pipes (7) is n, and 7≤n≤25; the micro-mixed injection pipes (7) are fixedly connected to the combustion disc and the first fixing disc (16) in a welded manner, and the open end of the fuel injection pipe (8) is fixedly connected to the second fixing disc (17) in a welded manner; the fuel injection pipe (8) and the micro-mixed injection pipe (7) are fixedly connected in a spaced spot welding manner, and sufficient air passages are reserved.

[0015] As a preferred scheme of the present application, the outer shape of the closed end of the fuel injection pipe (8) is in a conical structure.

[0016] As a preferred scheme of the present application, a uniform orifice plate (12) is arranged in the independent gas bin (6) in a transverse manner.

[0017] As a preferred embodiment of the present invention, the center distance between the duty combustion unit and each micro-mixing combustion unit is 65-80mm; the diameter of the premixed micro-mixing nozzle (7) is 3-8mm, and the spacing between adjacent nozzles is 2-3.5 times the nozzle diameter; the diameter of the premixed micro-orifice (15) is 0.5mm, which is smaller than the quenching diameter of the gas; sufficient internal space is reserved in the micro-mixing nozzle (7), specifically, the distance between the closed end of the fuel nozzle (8) and the outlet end of the micro-mixing nozzle (7) is 25-45mm.

[0018] As a preferred embodiment of the present invention, at least one ring of micro-mixed combustion units is uniformly arranged around the circumference of the duty combustion unit; when there are multiple rings, the radial distance between the rings of two adjacent micro-mixed combustion units is 65-80 mm.

[0019] Description of the invention principle:

[0020] When using existing technologies to blend high-hydrogen natural gas fuels, current combustion devices suffer from unstable combustion and NO emissions. x To address the issue of high emissions, this invention adopts an innovative approach, proposing a combustion device that combines central-shift stable combustion technology with micro-mixing interaction. Through the stable combustion effect of the central-shift swirling diffusion flame, a stable high-temperature heat source is provided for the peripheral micro-mixing small flames. By leveraging the interaction between flames, the safe, efficient, and low-emission application of natural gas with a high proportion of hydrogen blended fuel can be achieved.

[0021] 1. The micro-hybrid combustion unit includes components such as a coaxially arranged air cooling sleeve, an independent air chamber with an air inlet, and an independent gas chamber with a gas inlet. The micro-hybrid combustion unit can be independently controlled by supplying fuel / air separately, avoiding the problem of poor uniformity caused by different processing precision and flow resistance.

[0022] 2. The micro-hybrid combustion unit adopts a multi-stage radial arrangement structure. Based on the system's thermal power requirements, the combustion power can be precisely adjusted by changing the number of micro-hybrid combustion units in each ring. Alternatively, multiple rings of micro-hybrid combustion units can be arranged in a ring around the main combustion unit, with each ring maintaining a predetermined distance from the center, forming a multi-ring distribution pattern. These two arrangements can be flexibly configured separately or simultaneously, thereby achieving graded adjustment of the combustion system's thermal power output to meet operational needs under different conditions.

[0023] 3. In the micro-mixing combustion unit, the multi-array micro-mixing nozzles and fuel nozzles are uniformly welded to a fixed disk in a honeycomb pattern, and after installation, a sufficiently long gas / air premixing section is left in the nozzles. The gas is ejected at high speed through uniformly arranged single / multi-row circumferential premixing micro-holes on the sidewall of the fuel nozzle in a cross-jet collision manner; then, it is fully mixed with the surrounding air in the premixing section through a downstream conical structure, forming an ideally uniform micro-mixed premixed jet gas at the outlet of the micro-mixing nozzle. Each independent gas chamber is equipped with a uniform perforated plate to ensure that the hydrogen-rich blended gas is fully and uniformly mixed before entering the fuel nozzle, meeting the requirement of uniform blending of the set proportion of gas.

[0024] 4. The air cooling chamber, air cooling sleeve, and independent air chamber together constitute the oxidant air chamber and flow channel of the micro-mixing premixing unit. Air first enters through the air inlet on the side wall of the independent air chamber, flowing upwards through the air cooling chamber to cool the external structure of the burner. Then, it enters the interior of each micro-mixing combustion unit through multiple rows of evenly arranged air injection holes on the side wall of the air cooling sleeve to cool the micro-mixing nozzles, preventing damage to the internal structure of the burner from the high-temperature flame. Finally, air enters the independent air chamber from top to bottom through the disc through-holes of the first fixed disc, completing an axial circulation process before entering the multi-array micro-mixing nozzles for further uniform mixing with the combustion gas. During this process, the air, acting as a combustion aid, is heated, further improving the combustion efficiency of the combustion gas.

[0025] 5. The diameter of the premixing micro-orifices on the fuel nozzle is selected to be smaller than the quenching diameter of the fuel gas (when the equivalence ratio is 1, the quenching diameters of H2 and CH4 are 0.64 mm and 2.5 mm, respectively). The diameter of the micro-mixing nozzle is calculated based on the required thermal power and considering the high reactivity of hydrogen, and is selected to be a diameter corresponding to a flow velocity much greater than the hydrogen combustion velocity (the laminar flame velocity of H2 / air under normal temperature and pressure conditions is 2.8 m / s), i.e., 3–8 mm, to ensure the burner's anti-backfire performance. Furthermore, the premixing section length is set to 25–45 mm to achieve high-intensity mixing of fuel gas and oxidant at a small scale and appropriate mixing distance.

[0026] 6. The duty combustion unit adopts diffusion combustion. Air enters through the air jacket, flows through the cyclone separator, and ignites with the gas passing through the gas pipe at the burner outlet, forming a central swirling diffusion combustion flame. This maintains a stable high-temperature environment and provides a stable ignition heat source for the surrounding multi-element micro-mixed hydrogen-rich gas units. The stable ignition and combustion of the high hydrogen-doped gas in the micro-mixed combustion unit is achieved through the interaction between the swirling entrainment and the flame.

[0027] 7. The inner wall of the central annular sleeve of the hydrocyclone has a threaded structure, facilitating the replacement of hydrocyclones with different numbers of blades and blade angles. The spacing between the multi-array nozzles is 2 to 3.5 times the nozzle diameter to ensure good interaction between the central swirling diffusion flame and the multi-array micro-mixing flame cluster under different hydrogen doping ratios. By rationally setting the annular flow area of ​​the central air and the hydrocyclone blade angle, the air jet velocity is made 4 to 6 times that of the combustion gas, producing a significant shearing effect accompanied by an enhanced vortex structure, which is beneficial for the central control flame to swirl and entrain the surrounding smaller flames.

[0028] 8. In the micro-mixing combustion unit, the first and second fixed discs have a threaded outer wall structure while ensuring structural sealing. This allows for vertical adjustment of the distance between the premixing micro-holes and the burner outlet, and also facilitates the replacement of micro-mixing nozzles of different numbers and diameters to adapt to various operating conditions under different loads and hydrogen doping ratios.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The micro-mixed combustion units can be arranged radially and uniformly around the duty combustion unit. The combustion stabilization effect of the swirl duty flame solves the combustion oscillation and instability problems that often occur in large-proportion hydrogen-infused flames, achieving the dual composite effect of micro-mixed combustion technology and traditional diffusion swirl combustion. The fuel adaptability and combustion stability of the combustion device are improved.

[0031] 2. Millimeter-scale multi-array micro-mixing nozzles are arranged circumferentially on the burner outlet plane. A large number of small flames replace the traditional large flames, shortening the flame length and improving the temperature uniformity during the combustion reaction. The millimeter-scale diameter increases the jet velocity of the fuel / oxidant mixture, reducing the residence time of reactants in the high-temperature flame zone. At the same time, the premixing micropores uniformly arranged on the side wall of the nozzle allow the fuel gas and oxidant to be premixed in the micro-scale pipe. Therefore, a high-speed jet with strong mixing uniformity is formed at the burner outlet, which can effectively suppress NOx generation and reduce the risk of backfire.

[0032] 3. Each micro-hybrid combustion unit is equipped with an independent combustion chamber and air chamber; on the one hand, it realizes independent control of uniform gas distribution, thereby producing a spatially symmetrical and temperature-uniform array of micro-hybrid flame clusters; on the other hand, it improves the flexibility of gas / oxidizer air supply and avoids the impact of local component failure on the thermal power distribution of the combustion device.

[0033] 4. Make reasonable use of the structural characteristics of the combustion device and cleverly design the air cooling channel and oxidizer supply channel. After entering through the air inlet, the air flows through the air cooling chamber and then flows through multiple rows of injection holes on the side wall of the sleeve to flush the multi-array micro-mixing nozzle, which not only cools the burner head and prevents it from burning out due to high temperature, but also preheats the oxidizer.

[0034] 5. The sleeve of the cyclone is internally provided with threads, so that cyclones with different numbers of blades and blade angles can be conveniently replaced; the connection part of the honeycomb fixed disc is also designed as a threaded structure, so that the distance between the micro-mixing nozzle and the outlet of the combustor can be adjusted up and down, and different numbers and diameters of multi-array nozzles can be conveniently replaced to adapt to different thermal loads and hydrogen mixing ratios in different working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a longitudinal sectional view of the device of the present application.

[0036] Figure 2 is a schematic view of the on-duty combustion unit and the micro-mixing combustion unit during installation.

[0037] Figure 3 is a schematic view of the gas / oxidant gas supply structure.

[0038] Figure 4 is a partial schematic view of the micro-mixing combustion unit.

[0039] Figure 5 is a partial sectional schematic view of the micro-mixing combustion unit.

[0040] Figure 6 is Figure 4 is an enlarged view of the fuel nozzle in the selected area of the middle frame.

[0041] Reference signs in the figure: air cooling cavity 1; air bin fixing cavity 2; gas bin fixing cavity 3; air cooling sleeve 4; air shot hole 4-1; independent air bin 5; independent gas bin 6; micro-mixing nozzle 7; fuel nozzle 8; gas through pipe 9; air sleeve 10; cyclone 11; uniform hole plate 12; gas inlet 13; air inlet 14; premixing micro-hole 15; first fixed disc 16; disc through hole 16-1; second fixed disc 17. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application will be described in detail below in combination with the drawings and examples.

[0043] The serial numbers assigned to components in this application, such as "first" and "second," are merely for distinguishing the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this application and for simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0044] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0045] Part 1: Overview of the Implementation Schemes of the Invention

[0046] The swirl-operated multi-element micro-mixing coupled low-NOx combustion device for hydrogen-blended natural gas in this invention is specifically as follows: Figures 1-6 As shown. The main structure of the device includes an air cooling chamber 1, an air chamber fixing chamber 2, and a gas chamber fixing chamber 3 arranged sequentially from top to bottom. Specifically, the main body of the gas chamber fixing chamber 3 is a hollow cylindrical structure, and the edges of its upper and lower chamber plates extend laterally to form annular flanges; the air cooling chamber 1 and the air chamber fixing chamber 2 are both cylindrical structures with bottom openings, and the edges of the bottom openings extend laterally to form annular flanges; the air cooling chamber 1, the air chamber fixing chamber 2, and the gas chamber fixing chamber 3 are stacked sequentially, and are fastened by bolts passing through the through holes on the flanges.

[0047] In the center of the main structure, a shift combustion unit is arranged in the form of a sleeve structure penetrating through each chamber; specifically, it includes a gas passage tube 9 and an air sleeve 10 arranged coaxially, and a swirler 11 arranged in the annular region between the two, which is composed of a central sleeve and 8-12 swirler vanes arranged on the sleeve; the inner wall of the sleeve is provided with threads and is installed on the top of the gas passage tube 9 in a threaded manner, and the outer end surface is flush with the surface of the combustion disc; the axial angle between the swirler vanes and the sleeve is in the range of 30°-45°, and the air jet velocity is 4-6 times that of the gas by setting the annular flow area of the shift combustion unit and the angle of the swirler vanes.

[0048] Around the shift combustion unit, mounting holes are uniformly arranged on the chamber plates in the main structure, except for the bottom chamber plate of the gas bin fixing chamber 3; specifically, a plurality of circular openings matching the shape of the micro-mixed combustion unit are arranged on the chamber plates of the air cooling chamber 1, the air bin fixing chamber 2, and the upper chamber plate of the gas bin fixing chamber 3, respectively. In the air bin fixing chamber 2 and the gas bin fixing chamber 3, annular partitions are arranged along the edges of the mounting holes, forming independent air bins 5 and independent gas bins 6 that correspond one-to-one and are connected, thereby forming a plurality of embedded mounting positions arranged in a ring shape, for installing micro-mixed combustion units. The number of micro-mixed combustion units is the same as the number of embedded mounting positions, and after being inserted into the embedded mounting positions from top to bottom, they are seated on the lower chamber plate of the gas bin fixing chamber 3.

[0049] The micro-mixed combustion unit includes an air cooling sleeve 4, a micro-mixed nozzle 7, a fuel nozzle 8, and a second fixed disc 17. A combustion disc and a first fixed disc 16 are arranged at the top and bottom of the air cooling sleeve 4, respectively, each having a plurality of through holes arranged in an array and the through hole positions corresponding to each other. A plurality of micro-mixed nozzles 7 are arranged in an array along the axis inside the air cooling sleeve 4, with their two ends inserted into the through holes on the combustion disc and the first fixed disc 16, respectively. As an example, the number of micro-mixed nozzles 7 is n, 7≤n≤25. The micro-mixed nozzles 7 are fixedly connected to the combustion disc and the first fixed disc 16 by welding. A plurality of through holes are arranged in an array along the axis on the second fixed disc 17, with a single-end closed fuel nozzle 8 inserted into the upper end of each through hole; a plurality of premixed micro-holes 15 are uniformly arranged in a ring shape on the side wall near the closed end of the fuel nozzle 8; the closed end of the fuel nozzle 8 extends into the corresponding micro-mixed nozzle 7 and the premixed micro-holes 15 do not protrude, leaving enough internal space in the micro-mixed nozzle 7 for fuel and air mixing; the closed end of the fuel nozzle 8 has a conical structure. The open end of the fuel nozzle 8 is fixedly connected to the second fixed disc 17 by welding; the fuel nozzle 8 and the micro-mixed nozzle 7 are fixedly connected by spot welding at intervals, leaving sufficient air passages.

[0050] The plurality of micro-combustion units are respectively inserted into the embedded installation positions, and the air cooling sleeve 4, the first fixed disc 16 and the second fixed disc 17 are matched with the corresponding installation holes on the chamber plate to seal the independent air chamber 5 and the independent gas chamber 6. Specifically, threads are arranged on the edges of the first fixed disc 16 and the second fixed disc 17, and corresponding threads are arranged on the chamber plate opening holes corresponding to the two discs. The micro-combustion units are downwardly inserted into the opening holes of the chamber plates and are sealingly installed in a spiral manner. The bottom chamber plate of the gas chamber fixing cavity 3 is provided with a gas inlet (13) connected to the independent gas chamber 6, and the gas inlet (13) is exemplified as a through pipe. The independent gas chamber 6 is provided with a transversely arranged uniform hole plate 12, and the radial dimension of the hole plate 12 is matched with the inner diameter of the independent gas chamber 6.

[0051] The air inlet 14 is arranged on the side wall of the air cooling cavity 1, the air chamber fixing cavity 2 or the gas chamber fixing cavity 3, air through holes are arranged on the chamber plates between the corresponding cavities, a plurality of air injection holes 4-1 are arranged on the side wall of the air cooling sleeve 4, disc through holes 16-1 are arranged on the first fixed disc 16, and a gap is maintained between the micro-mixing injection pipe 7 and the fuel injection pipe 8; in this way, an air flow path is formed, and after the external air is introduced to cool the burner head, the heated air is mixed with fuel for combustion. As an example, the air inlet 14 is arranged on the side wall of the air chamber fixing cavity 2, and through holes are arranged on the chamber plates of the air cooling cavity 1 and the air chamber fixing cavity 2 to communicate the air flow path.

[0052] As an example, the center distance between the standby combustion unit and each micro-combustion unit is 65-80 mm, the distance between each micro-mixing injection pipe 7 in the micro-combustion unit is 2-3.5 times the diameter of the injection pipe, the diameter of the premixed micro-hole 15 is 3-8 mm, which is smaller than the quenching diameter of the gas, and sufficient internal space is reserved in the micro-mixing injection pipe 7, specifically, the distance between the closed end of the fuel injection pipe 8 and the outlet end of the micro-mixing injection pipe 7 is 25-45 mm. Taking the standby combustion unit as the center, at least one or more rings of micro-combustion units can be uniformly arranged circumferentially; when there are multiple rings, the radial distance of the annular space where the adjacent two rings of micro-combustion units are located is 65-80 mm.

[0053] A specific example of the second part

[0054] This example is a 100kW laboratory / industrial transition scale natural gas hydrogen blending burner, the center distance between the standby combustion unit and each micro-combustion unit is 80mm, the array injection pipe in the micro-combustion unit is 19 holes, and the swirler is composed of 8 pieces of 45° spiral blades. In this burner, the swirl diffusion flame bears 10% of the heat load demand, and the six micro-combustion units together bear 90kW of heat load (each with an average of 15kW of heat power). The equivalence ratio in the example is 0.8, and the volume blending ratio of hydrogen reaches more than 85%.

[0055] The combustion device comprises air cooling cavity, air warehouse fixed cavity and gas warehouse fixed cavity arranged in sequence from top to bottom. The 19-hole multi-array micro-mixing nozzle and fuel nozzle are arranged in a honeycomb distribution between the first fixed disc and the second fixed disc, and the cooperation of the two is adjusted during installation to leave a 40-45mm gas / air premixing section in the micro-mixing nozzle. Each micro-mixing combustion unit is coaxially installed in the installation position formed by the independent air warehouse and the independent gas warehouse, and the swirl generator is located at the outlet end face of the burner by adjusting the thread rotation depth of the fixed disc.

[0056] The combustion device comprises the center air (oxidant) inlet and gas inlet of the duty combustion unit, and the mixed gas inlet and air inlet of the plurality of independently controlled micro-mixing combustion units. The center air and gas are ignited at the burner outlet through the center sleeve structure to form a swirl diffusion combustion flame, which provides a high-temperature environment and a stable ignition source for the micro-mixing array small flame cluster. The air of each micro-mixing combustion unit first enters the system through the air inlet arranged on the side wall of the independent air warehouse, then flows through the air cooling cavity, and then passes through the multiple rows of air injection holes uniformly distributed on the side wall of the air cooling sleeve to implement the flush cooling of the multi-array micro-mixing nozzle, so as to realize the effective cooling of the burner head and prevent the burning caused by high-temperature flame. Thereafter, the air is refluxed to the independent air warehouse through the disc passage, and the top-down circulation flow process is completed. Further, the hydrogen-rich gas is high-speed injected in the form of cross-jet through the premixing micro-holes arranged on the side wall of the fuel nozzle, collides with the air entering the multi-array micro-mixing nozzle, realizes small-scale high-intensity mixing in the premixing section, and the component mixing uniformity reaches 0.99. Finally, an ideal premixed fully developed high-speed jet is formed at the downstream burner outlet, and the mixed gas flow rate reaches 25-35m / s. At this time, the premixed gas is ignited by the flame of the duty combustion unit, and the obvious entrainment effect and the tendency of the flame to move to the center are observed, and finally a spatially symmetric, uniform and stable micro-mixing multi-array small flame cluster is formed, and the outlet NOx<30mg / Nm 3 . The method significantly improves the combustion efficiency and stability by optimizing the flow path and mixing mode of air and gas.

[0057] The structure size, unit quantity, power distribution, and working condition calculation can be adjusted according to actual needs through a large number of experiments of the inventor team. For example, the equivalence ratio range of the combustion device based on the design concept of the application includes gas blowout lean limit to 1.2, the gas of the standby combustion unit can use natural gas or mixed with a certain proportion of hydrogen-rich gas, the hydrogen mixing ratio of the mixed combustion unit includes the range of 20% to 100%. The number of the surrounding micro-mixed combustion units can be different numbers or different rings, the number of the micro-mixed array holes can be adjusted according to the actual situation, the length of the premixing section is adjusted according to the aperture and spacing of the premixing micro-hole, and the center distance of the standby / micro-mixed combustion unit can be expanded / reduced.

[0058] The above examples are only used to illustrate the technical solutions of the application and the beneficial effects, and cannot be used as the basis for limiting the scope of patent protection. Any improvement and optimization based on the application should be included in the scope of patent protection on the premise of meeting the core principles and design concepts of the application. The parameter values provided in the embodiments of the application are only for reference, and the structure size and combustion load can be appropriately adjusted within the allowable error range according to the specific working conditions and scenes in actual application, and the specific implementation method and performance index are optimized. The setting of these parameters considers the reasonable deviation in engineering practice, and necessary adjustment is allowed under the premise of meeting the design requirements.

Claims

1. A swirl duty multi-element micro-mixing coupled low-NOx combustion device for hydrogen-doped natural gas, characterized by, The main structure of the device comprises air cooling cavity (1), air warehouse fixed cavity (2) and gas warehouse fixed cavity (3) arranged in sequence from top to bottom; a sleeve structure duty combustion unit is arranged in the center of the main structure in a way of penetrating each cavity, comprising coaxially arranged gas pipe (9) and air sleeve (10); along the circumference, installation holes are uniformly arranged on the cavity plate of the main structure around the duty combustion unit as the center, except the bottom cavity plate of the gas warehouse fixed cavity (3); annular partition plates are arranged along the edge of each installation hole in the air warehouse fixed cavity (2) and the gas warehouse fixed cavity (3), forming one-to-one corresponding and communicating independent air warehouse (5) and independent gas warehouse (6), thereby forming a plurality of embedded installation positions arranged in a ring shape. The device also comprises a plurality of micro-mixed combustion units equal to the number of embedded installation positions, comprising air cooling sleeve (4) and second fixed disc (17); at the top and bottom of the air cooling sleeve (4), combustion disc and first fixed disc (16) are arranged respectively, each having a plurality of through holes arranged in an array and the through hole positions corresponding to each other; a plurality of micro-mixed injection pipes (7) are arranged in an array along the axis in the inside of the air cooling sleeve (4), and the two ends of each micro-mixed injection pipe (7) are inserted into the through holes on the combustion disc and the first fixed disc (16) respectively; a plurality of through holes are arranged in an array along the axis on the second fixed disc (17), and a single-end closed fuel injection pipe (8) is inserted into the upper end of each through hole; a plurality of premixed micro-holes (15) are uniformly arranged in a ring shape on the side wall close to the closed end of the fuel injection pipe (8); the closed end of the fuel injection pipe (8) extends into the corresponding micro-mixed injection pipe (7) and the premixed micro-hole (15) does not protrude, leaving enough internal space in the micro-mixed injection pipe (7) for fuel and air mixing; a plurality of micro-mixed combustion units are inserted into the embedded installation positions respectively, and the air cooling sleeve (4), the first fixed disc (16) and the second fixed disc (17) are matched with the corresponding installation holes on the cavity plate, thereby sealing the independent air warehouse (5) and the independent gas warehouse (6); the gas inlet (13) connected with the independent gas warehouse (6) is arranged on the bottom cavity plate of the gas warehouse fixed cavity (3); The air inlet (14) is arranged on the side wall of the air cooling cavity (1), the air warehouse fixed cavity (2) or the gas warehouse fixed cavity (3), the air through hole is arranged on the cavity plate between the corresponding cavities, the air shooting hole (4-1) is arranged on the side wall of the air cooling sleeve (4), the disc through hole (16-1) is arranged on the first fixed disc (16), and the gap is maintained between the micro-mixed injection pipe (7) and the fuel injection pipe (8); in this way, the air flow path is formed, after the external air is introduced to cool the head of the burner, the heated air is mixed with the fuel for combustion.

2. The apparatus of claim 1, wherein, The main body of the gas bin fixing cavity (3) is in a hollow cylindrical structure, and the edges of the upper and lower cavity plates extend transversely to form annular flange rings; the air cooling cavity (1) and the air bin fixing cavity (2) are both in a barrel shape with an open bottom, and the edges of the open bottom extend transversely to form annular flange rings; the air cooling cavity (1), the air bin fixing cavity (2) and the gas bin fixing cavity (3) are stacked in sequence, and fastening installation is realized by means of bolts penetrating through the through holes in the flange rings.

3. The apparatus of claim 1, wherein, A plurality of circular openings matching the shapes of the micro-mixed combustion units are respectively arranged on the cavity plates of the air cooling cavity (1), the air bin fixing cavity (2) and the upper cavity plate of the gas bin fixing cavity (3); the micro-mixed combustion units pass through the openings from top to bottom and are seated on the lower cavity plate of the gas bin fixing cavity (3); the gas inlet (13) is a pipe penetrating through the lower cavity plate of the gas bin fixing cavity (3).

4. The apparatus of claim 1, wherein, In the micro-mixed combustion unit, threads are arranged on the edges of the first fixing disc (16) and the second fixing disc (17), and matching threads are arranged on the opening holes of the cavity plates corresponding to the two discs; the micro-mixed combustion unit is inserted into the opening holes of the cavity plates in a downward direction and is installed in a sealed manner in a spiral way.

5. The apparatus of claim 1, wherein, An air cyclone (11) is arranged in the annular area between the gas passage pipe (9) and the air sleeve pipe (10) and is composed of a central sleeve and 8-12 cyclone blades arranged on the sleeve; the inner wall of the sleeve is provided with threads and is installed on the top of the gas passage pipe (9) in a threaded fitting manner, and the outer end surface is flush with the surface of the combustion disc; the axial angle between the cyclone blades and the sleeve is in the range of 30°-45°, and the air jet velocity is 4-6 times that of the gas by setting the annular flow area of the on-duty combustion unit and the angle of the cyclone blades.

6. The apparatus of claim 1, wherein, The number of the micro-mixed injection pipes (7) is n, and 7≤n≤25; the micro-mixed injection pipes (7) are fixedly connected to the combustion disc and the first fixing disc (16) in a welded manner, and the open end of the fuel injection pipe (8) is fixedly connected to the second fixing disc (17) in a welded manner; the fuel injection pipe (8) and the micro-mixed injection pipe (7) are fixedly connected in a spaced spot welding manner, and sufficient air passages are reserved.

7. The apparatus of claim 1, wherein, The outer shape of the closed end of the fuel injection pipe (8) is in a conical structure.

8. The apparatus of claim 1, wherein, In the independent gas bin (6), a transversely arranged uniform orifice plate (12) is arranged.

9. The apparatus of claim 1, wherein, The center distance between the on-duty combustion unit and each micro-mixed combustion unit is 65-80 mm; the diameter of the premixed micro-mixed injection pipe (7) is 3-8 mm, and the distance between adjacent injection pipes is 2-3.5 times the diameter of the injection pipe; the diameter of the premixed micro-hole (15) is 0.5 mm, which is smaller than the quenching diameter of the gas; sufficient internal space is reserved in the micro-mixed injection pipe (7), specifically, the distance between the closed end of the fuel injection pipe (8) and the outlet end of the micro-mixed injection pipe (7) is 25-45 mm.

10. The apparatus of claim 1, wherein, At least one circle of micro-mixed combustion units is arranged uniformly around the on-duty combustion unit in a circumferential direction; when there are multiple circles, the radial distance of the annular area where the adjacent two circles of micro-mixed combustion units are located is 65-80 mm.

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