Rotational flow on-duty multi-element micro-mixing coupling type low-nitrogen combustion device for hydrogen-doped natural gas

Abstract

The invention relates to a clean energy combustion technology, and aims to provide a rotational flow on-duty multi-element micro-mixing coupling type low-nitrogen combustion device for hydrogen-doped natural gas. Comprising an air cooling cavity, an air bin fixing cavity and a gas bin fixing cavity which are sequentially stacked from top to bottom. An on-duty combustion unit of a sleeve structure is arranged in the center of the burner in a penetrating mode, and micro-mixing combustion units, independent air bins and independent fuel gas bins are evenly arranged in the circumferential direction in a surrounding mode. A plurality of micro-mixing spray pipes are arranged in an air cooling sleeve of the micro-mixing combustion unit in the axial direction in an array mode, and fuel spray pipes are arranged on a second fixed disc in the axial direction in an array mode. The closed end of the fuel spray pipe extends into the micro-mixing spray pipe corresponding to the fuel spray pipe, and a fuel gas inlet is formed in the bottom of the fuel gas bin fixing cavity. After external air is introduced through an air circulation path from top to bottom to cool the head of the combustor, the heated air is mixed with fuel for combustion, and safe, efficient and low-emission application of natural gas large-proportion hydrogen-doped fuel is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of clean energy combustion, and particularly relates to a swirling pilot multi-element micro-mixing coupling type low-nitrogen combustion device for hydrogen-enriched natural gas. Background Art

[0002] With the popularization and practice of the concept of green environmental protection, the trend of using clean and low-carbon fuels to replace traditional fossil energy combustion has gradually emerged. Hydrogen has the advantages of wide sources, zero carbon emissions, high calorific value, etc., and is exactly a carbon-free alternative fuel with great potential in gas turbines, industrial boilers and aero-engine equipment. As a new micro-mixing combustion technology developed for the next-generation high-efficiency and low-carbon gas turbines, the fuels used are mostly hydrogen-rich or even pure hydrogen fuels. Micro-mixing combustion replaces traditional large nozzles with numerous millimeter-diameter micro-mixing nozzles with simplified structures. Multiple arrays of micro-channels convert large-scale flames into multiple tiny flames, effectively suppressing the flashback of hydrogen and evenly distributing the heat load. It is one of the most promising hydrogen combustion technologies and development directions at present. Due to the excessively high costs of hydrogen production, storage and transportation, using hydrogen alone as a fuel cannot be promoted in a wider range of application fields. Therefore, mixing hydrogen with a large proportion of natural gas (such as the volume of natural gas blending being greater than 30% or even more) and using it as a fuel, and providing corresponding combustion devices therefor, have become research directions concerned in the industry.

[0003] However, due to the large differences in the physical and chemical properties and combustion characteristics of hydrogen and natural gas, especially the reaction activity and flame propagation speed of hydrogen being much higher than those of natural gas, the risk of flashback is relatively high, and there are also problems of unstable combustion and relatively high thermal NOx emissions. This makes the existing pure hydrogen or hydrogen-rich micro-mixing burner structures, as well as traditional dry low-emission premixed combustion technologies, difficult to be applicable to hydrogen-enriched natural gas fuels with a relatively high proportion of natural gas.

[0004] Therefore, the present invention intends to propose a new solution to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a swirling pilot multi-element micro-mixing coupling type low-nitrogen combustion device for hydrogen-enriched natural gas.

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

[0007] Provided is a swirl duty multi - micro - mixing coupled low - nitrogen combustion device for hydrogen - doped natural gas. The main structure of the device includes an air cooling chamber (1), an air storage fixed chamber (2), and a gas storage fixed chamber (3) which are arranged in layers from top to bottom in sequence; in the center of the main structure, there is a duty combustion unit with a sleeve structure that penetrates through each chamber, including a gas - passing pipe (9) and an air sleeve (10) arranged coaxially; centered on the duty combustion unit, mounting holes are evenly arranged circumferentially on the chamber plates of each chamber in the main structure, except for the bottom chamber plate of the gas storage fixed chamber (3); annular partitions are provided along the edges of each mounting hole in the air storage fixed chamber (2) and the gas storage fixed chamber (3), respectively forming independent air storage chambers (5) and independent gas storage chambers (6) that correspond one - to - one and are connected, thus constituting a plurality of embedded mounting positions arranged alternately in the circumferential direction;

[0008] The device also includes micro - mixing combustion units with the same number as the number of embedded mounting positions, including an air cooling sleeve (4) and a second fixed disk (17); at the top and bottom ends of the air cooling sleeve (4), a combustion disk and a first fixed disk (16) are respectively arranged, each having a number of through - holes arranged in an array and the through - hole positions corresponding to each other; a number of micro - mixing nozzles (7) are arranged axially in an array inside the air cooling sleeve (4), and both ends of which are respectively inserted into the through - holes on the combustion disk and the first fixed disk (16); on the second fixed disk (17), a number of through - holes are arranged axially in an array, and a fuel nozzle (8) with one end closed is inserted into the upper end of each through - hole; on the side wall near the closed end of the fuel nozzle (8), a number of premixing micro - holes (15) are arranged circumferentially and evenly; the closed end of the fuel nozzle (8) extends into the corresponding micro - mixing nozzle (7) and the premixing micro - holes (15) are not exposed, and enough internal space is reserved in the micro - mixing nozzle (7) for fuel - air mixing; a plurality of micro - mixing combustion units are respectively inserted into the embedded mounting positions, and the air cooling sleeve (4), the first fixed disk (16), and the second fixed disk (17) are adapted to the corresponding mounting holes on each chamber plate to seal the independent air storage chamber (5) and the independent gas storage chamber (6); a gas inlet (13) connecting the independent gas storage chamber (6) is provided on the bottom chamber plate of the gas storage fixed chamber (3);

[0009] An air inlet (14) is provided on the side wall of the air cooling chamber (1), the air storage fixed chamber (2), or the gas storage fixed chamber (3), air through - holes are provided on the chamber plates between the corresponding chambers, a number of air injection holes (4 - 1) are provided on the side wall of the air cooling sleeve (4), disk - through holes (16 - 1) are provided on the first fixed disk (16), and a gap is maintained between the micro - mixing nozzle (7) and the fuel nozzle (8); in this way, an air flow path is formed. After introducing external air to cool the burner head, the heated air is then mixed with fuel for combustion.

[0010] As a preferred embodiment of the present invention, the main body of the gas storage chamber fixing cavity (3) is of a hollow cylindrical structure, and the edges of the upper and lower chamber plates thereof extend horizontally to form an annular flange; the air cooling cavity (1) and the air storage chamber fixing cavity (2) are both of a cylindrical structure with an open bottom, and the edges of the open bottom extend horizontally to form an annular flange; the air cooling cavity (1), the air storage chamber fixing cavity (2) and the gas storage chamber fixing cavity (3) are superposed in sequence, and are firmly installed by bolts passing through the through holes on the flange.

[0011] As a preferred embodiment of the present invention, on the chamber plates of the air cooling cavity (1) and the air storage chamber fixing cavity (2) and the upper chamber plate of the gas storage chamber fixing cavity (3), a plurality of circular openings matching the outer shapes of the respective micro-mixing combustion units are respectively provided; after passing through the respective openings from top to bottom, the micro-mixing combustion units are seated on the lower chamber plate of the gas storage chamber fixing cavity (3); the gas inlet (13) is a pipe fitting passing through the lower chamber plate of the gas storage chamber fixing cavity (3).

[0012] As a preferred embodiment of the present invention, in the micro-mixing combustion unit, threads are respectively provided at the edges of the first fixing disk (16) and the second fixing disk (17), and matching threads are respectively provided at the openings of the chamber plates corresponding to the two disks; the micro-mixing combustion unit is inserted downward into the openings of the respective chamber plates and is hermetically installed in a spiral manner.

[0013] As a preferred embodiment of the present invention, a swirler (11) is provided in the annular region between the gas pipe (9) and the air sleeve (10), which is composed of a central sleeve and 8 to 12 swirler vanes provided on the sleeve; threads are provided on the inner wall of the sleeve and the sleeve is installed on the top of the gas pipe (9) in a threaded fit manner, and its outer end face is flush with the surface of the combustion disk; the axial angle range of the swirler vanes and the sleeve is 30° to 45°, and the air jet velocity is 4 to 6 times that of the gas by setting the annular flow area of the pilot combustion unit and the angle of the swirler vanes.

[0014] As a preferred embodiment of the present invention, the number of the micro-mixing nozzles (7) is n, where 7 ≤ n ≤ 25; the micro-mixing nozzles (7) are fixedly connected to the combustion disk and the first fixing disk (16) by welding, and the open end of the fuel nozzle (8) is fixedly connected to the second fixing disk (17) by welding; the fuel nozzle (8) and the micro-mixing nozzle (7) are fixedly connected by spot welding at intervals, leaving sufficient air channels.

[0015] As a preferred embodiment of the present invention, the outer shape of the closed end of the fuel nozzle (8) is of a conical structure.

[0016] As a preferred embodiment of the present invention, in the independent gas storage chamber (6), a uniformly distributed orifice plate (12) is provided horizontally.

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

[0018] As a preferred embodiment of the present invention, at least one circle of micro-mixing combustion units is evenly arranged circumferentially around the duty combustion unit; when there are multiple circles, the radial distance between the circumferences where adjacent two circles of micro-mixing combustion units are located is 65-80 mm.

[0019] Description of the invention principle:

[0020] Aiming at the problems of unstable combustion and high NO x emissions in the existing combustion devices when using high-hydrogen-doped natural gas fuel, the present invention adopts an innovative idea and proposes a combustion device that combines the central duty flame stabilization technology and the interaction of micro-mixing. Through the flame stabilization effect of the central duty swirling diffusion flame, a stable high-temperature heat source is provided for the peripheral micro-mixed small flames. With the help of the interaction between the flames, the safe, efficient, and low-emission application of natural gas fuel with a large proportion of hydrogen is realized.

[0021] 1. The micro-mixing combustion unit includes components such as an air-cooling sleeve arranged coaxially, an independent air chamber equipped with an air inlet, and an independent fuel gas chamber equipped with a fuel gas inlet. The independent control of the micro-mixing combustion unit is realized through separate supply of fuel / air, avoiding the problem of poor uniformity caused by different processing precisions and flow resistances.

[0022] 2. The micro-mixing combustion unit adopts a multi-stage radial arrangement structure. According to the system heat power demand, the combustion power can be precisely adjusted by adjusting the circumferential number of the micro-mixing combustion units. Alternatively, further, multiple circles of micro-mixing combustion units are arranged in a ring around the duty combustion unit, and each circle of micro-mixing combustion units maintains a predetermined distance from the center, forming a multi-ring distribution pattern. The two arrangement methods can be flexibly configured separately or simultaneously, so as to realize the hierarchical adjustment of the heat power output of the combustion system and meet the operation requirements under different working conditions.

[0023] 3. The multi-array micro-mixing nozzles and fuel nozzles in the micro-mixing combustion unit are evenly welded to the fixed disk in a honeycomb distribution. After they are assembled, there is a sufficient length of gas / air premixed section in the nozzles. The gas is ejected at high speed in the form of cross-jet impingement through the single-row / multi-row circumferential premixing micro-holes evenly arranged on the side wall of the fuel nozzle. Then, it is fully mixed with the surrounding air in the premixed section through the downstream conical structure, and an ideal and uniform micro-mixed premixed jet gas is formed at the outlet of the micro-mixing nozzle. Uniform orifice plates are provided in each independent gas chamber to ensure that the hydrogen-rich blended gas is fully and evenly mixed before entering the fuel nozzle, meeting the requirement of uniformly blending the gas at a set ratio.

[0024] 4. The air cooling cavity, air cooling sleeve, and independent air chamber together form the oxidant air chamber and flow channel of the micro-mixed premixing unit. Air first enters from the air inlet on the side wall of the independent air chamber and flows upward through the air cooling cavity to cool the external structure of the burner. Subsequently, it enters the interior of each micro-mixing combustion unit through the multi-row air injection holes evenly arranged on the side wall of the air cooling sleeve to cool the micro-mixing nozzles, preventing the high-temperature flame from damaging the internal structure of the burner. Finally, the air enters the independent air chamber from top to bottom through the disk through-holes of the first fixed disk. After completing the axial circulation process, it enters the multi-array micro-mixing nozzles to be further evenly mixed with the gas. During this process, the air as the combustion-supporting agent is heated up, further improving the combustion efficiency of the gas.

[0025] 5. The diameter of the premixing micro-holes on the fuel nozzle is selected to be smaller than the quenching diameter of the 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 and selected to be much larger than the flow velocity corresponding diameter of the hydrogen combustion speed (the laminar flame speed of H2 / air under normal temperature and pressure is 2.8 m / s) according to the requirement of the thermal power, that is, 3 - 8 mm, in order to ensure the anti-flashback performance of the burner. Moreover, the length of the premixed section is set to be 25 - 45 mm to achieve high-intensity mixing of the gas and the oxidant at a small scale and an appropriate mixing distance.

[0026] 6. The duty combustion unit adopts the diffusion combustion method. Air enters from the air sleeve, flows through the swirler and is ignited at the outlet of the burner with the gas passing through the gas pipe, forming a central swirling diffusion combustion flame to maintain a stable high-temperature environment, providing a stable ignition heat source for the surrounding circumferentially arranged multi-element micro-mixed hydrogen-rich gas units, and realizing the stable ignition and combustion of the high-hydrogen-content gas in the micro-mixing combustion unit through swirl entrainment and the interaction between flames.

[0027] 7. The inner wall of the central annular sleeve of the cyclone is threaded, which facilitates the replacement of cyclones with different numbers of blades and blade angle profiles. The spacing of 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 clusters at different hydrogen addition ratios. By reasonably setting the annular flow area of the central air and the cyclone blade angle, the jet velocity of the air is 4 to 6 times that of the fuel gas, generating an obvious shear effect and accompanied by an enhanced vortex structure, which is conducive to the swirling entrainment of the central pilot flame on the surrounding small flames.

[0028] 8. On the premise of ensuring the structural sealing performance, the outer walls of the first fixed disk and the second fixed disk in the micro-mixing combustion unit are threaded. This not only allows for the vertical adjustment of the distance between the premixing micro-holes and the burner outlet but also facilitates the replacement of micro-mixing nozzles with different numbers and diameters to adapt to various operating conditions at different loads and hydrogen addition ratios.

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

[0030] 1. The micro-mixing combustion units can be arranged in a multi-stage radial circumferential and uniform manner around the pilot combustion unit. By stabilizing the combustion of the swirling pilot flame, the combustion oscillation and instability problems often occurring in high-hydrogen-content flames are solved, achieving the double composite effect of integrating the micro-mixing combustion technology with the traditional diffusion swirling combustion, and improving the fuel adaptability and combustion stability of the combustion device.

[0031] 2. The millimeter-scale multi-array micro-mixing nozzles are circumferentially arranged on the burner outlet plane. A large number of small flames are used to replace the traditional large flame, shortening the flame length and improving the temperature uniformity during the combustion reaction process. The millimeter-scale diameter increases the jet velocity of the fuel / oxidant mixture, reduces the residence time of the reactants in the high-temperature flame zone. At the same time, the premixing micro-holes uniformly arranged on the side walls of the nozzles enable the pre-mixing of the fuel gas and the oxidant in the micro-scale pipelines. Therefore, a high-speed jet with strong mixing uniformity is formed at the burner outlet, which can effectively inhibit the generation of NOx and reduce the risk of flashback.

[0032] 3. Each micro-mixing combustion unit is equipped with an independent combustion chamber and air chamber. On the one hand, it realizes the independent control of uniform gas distribution, thus generating an array of micro-mixing flame clusters with spatial symmetry and uniform temperature. On the other hand, it improves the flexibility of the fuel gas / oxidant air supply and avoids the influence of local component failures on the thermal power distribution of the combustion device.

[0033] 4. By reasonably utilizing the structural characteristics of the combustion device, the air cooling channel and the oxidant supply channel are ingeniously designed. The air enters from the air inlet and flows through the air cooling cavity, and then flushes the multi-array micro-mixing nozzles through multiple rows of injection holes on the side wall of the sleeve, which not only cools the burner head to avoid high-temperature thermal burnout but also preheats the oxidant.

[0034] 5. The inside of the sleeve of the cyclone is provided with threads, which can realize the convenient replacement of cyclones with different numbers of blades and vane angle types; the connection part of the honeycomb fixed disc is also designed as a threaded structure, which can adjust the distance between the micro-mixing nozzle and the burner outlet up and down, and at the same time facilitate the replacement of multi-array nozzles with different numbers and diameters to meet the requirements of different heat loads and hydrogen addition ratios under multiple working conditions. Brief Description of the Drawings

[0035] Figure 1 It is a schematic longitudinal sectional view of the device of the present invention patent.

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

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

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

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

[0040] Figure 6 It is Figure 4 an enlarged view of the fuel nozzle in the framed area in

[0041] Reference numerals in the drawings: air cooling cavity 1; air storage fixed cavity 2; gas storage fixed cavity 3; air cooling sleeve 4; air injection hole 4-1; independent air storage 5; independent gas storage 6; micro-mixing nozzle 7; fuel nozzle 8; gas pipe 9; air sleeve 10; cyclone 11; uniform orifice plate 12; gas inlet 13; air inlet 14; premixed micropores 15; first fixed disc 16; disc through hole 16-1; second fixed disc 17. Detailed Description of the Preferred Embodiments

[0042] The following will describe in detail the specific embodiments of the present invention with reference to the drawings and examples.

[0043] In this application, the serial numbers assigned to components themselves, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meaning. The terms "connection" and "coupling" as used in this application, unless otherwise specifically stated, both include direct and indirect connection (coupling). In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application.

[0044] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0045] Part I Summary of the implementation solution of the present invention

[0046] The swirl duty multi - micro - mixing coupling type low - nitrogen combustion device for hydrogen - doped natural gas in the present invention is specifically as Figures 1-6 shown. The main structure of this device includes an air cooling chamber 1, an air storage fixed chamber 2, and a gas storage fixed chamber 3 that are stacked in sequence from top to bottom. Specifically, the main body of the gas storage fixed chamber 3 has a hollow cylindrical structure, and the edges of its upper and lower chamber plates extend horizontally to form an annular flange; both the air cooling chamber 1 and the air storage fixed chamber 2 have a barrel - shaped structure with an open bottom, and the edges of the open bottom extend horizontally to form an annular flange; the air cooling chamber 1, the air storage fixed chamber 2, and the gas storage fixed chamber 3 are stacked in sequence, and are firmly installed by bolts passing through the through - holes on the flange.

[0047] At the center of the main structure and in a way that penetrates through each chamber, there is a duty combustion unit with a sleeve structure; specifically, it includes a gas conduit 9 and an air sleeve 10 arranged coaxially. A swirler 11 is provided in the annular region between the two. The swirler 11 is composed of a central sleeve and 8 to 12 swirl vanes arranged on the sleeve. The inner wall of the sleeve is provided with threads and is installed at the top of the gas conduit 9 in a threaded fit manner, and its outer end surface is flush with the surface of the combustion disk. The axial angle range of the swirl vanes with respect to the sleeve is 30° to 45°. By setting the annular flow area of the duty combustion unit and the angle of the swirl vanes, the air jet velocity is 4 to 6 times that of the gas.

[0048] Centered on the duty combustion unit, mounting holes are evenly arranged circumferentially on the chamber plates of the main structure, except for the bottom chamber plate of the gas storage fixed chamber 3; specifically, on the chamber plates of the air cooling chamber 1, the air storage fixed chamber 2, and the upper chamber plate of the gas storage fixed chamber 3, there are respectively a plurality of circular openings that match the outer shape of the micro-mixing combustion unit. Annular partitions are provided along the edges of the mounting holes in the air storage fixed chamber 2 and the gas storage fixed chamber 3, respectively forming independent air storage chambers 5 and independent gas storage chambers 6 that correspond to each other and are connected, thereby constituting a plurality of embedded mounting positions arranged alternately in the circumferential direction for installing the micro-mixing combustion units. The number of micro-mixing combustion units is the same as the number of embedded mounting positions. After being inserted into the embedded mounting positions from top to bottom, they are seated on the lower chamber plate of the gas storage fixed chamber 3.

[0049] The micro-mixing combustion unit includes an air cooling sleeve 4, a micro-mixing nozzle 7, a fuel nozzle 8, and a second fixed disk 17. At the top and bottom ends of the air cooling sleeve 4, a combustion disk and a first fixed disk 16 are respectively provided, each having a plurality of through holes arranged in an array and the through hole positions corresponding to each other. A plurality of micro-mixing nozzles 7 are arranged axially in an array inside the air cooling sleeve 4, and both ends thereof are respectively inserted into the through holes on the combustion disk and the first fixed disk 16. As an example, the number of micro-mixing nozzles 7 is n, where 7 ≤ n ≤ 25. The micro-mixing nozzles 7 are fixedly connected to the combustion disk and the first fixed disk 16 by welding. On the second fixed disk 17, a plurality of through holes are arranged axially in an array, and a single-end closed fuel nozzle 8 is inserted into the upper end of each through hole; on the side wall near the closed end of the fuel nozzle 8, a plurality of premixing micro-holes 15 are arranged circumferentially and evenly; the closed end of the fuel nozzle 8 extends into the corresponding micro-mixing nozzle 7 and the premixing micro-holes 15 are not exposed, leaving enough internal space in the micro-mixing nozzle 7 for fuel and air mixing; the outer shape of the closed end of the fuel nozzle 8 is a conical structure. The open end of the fuel nozzle 8 is fixedly connected to the second fixed disk 17 by welding; the fuel nozzle 8 and the micro-mixing nozzle 7 are fixedly connected by spot welding at intervals, leaving sufficient air channels.

[0050] Multiple micro-mixing combustion units are respectively inserted into the embedded installation positions. The air cooling sleeve 4, the first fixing disc 16 and the second fixing disc 17 are adapted to the corresponding mounting holes on each chamber plate to seal the independent air chamber 5 and the independent gas chamber 6. Specifically, threads are respectively provided at the edges of the first fixing disc 16 and the second fixing disc 17, and mating threads are respectively provided at the openings of the chamber plates corresponding to the two discs. The micro-mixing combustion units are inserted downward into the openings of each chamber plate and are hermetically installed in a spiral manner. At the bottom chamber plate of the gas chamber fixing cavity 3, a gas inlet (13) connecting the independent gas chamber 6 is provided. The gas inlet (13) is exemplified by a pipe fitting arranged through. In the independent gas chamber 6, a uniformly arranged orifice plate 12 is provided horizontally, and its radial dimension is adapted to the inner diameter of the independent gas chamber 6.

[0051] An air inlet 14 is provided on the side wall of the air cooling chamber 1, the air chamber fixing cavity 2 or the gas chamber fixing cavity 3. An air through hole is provided on the chamber plate between the corresponding chambers. A number of air injection holes 4-1 are provided on the side wall of the air cooling sleeve 4. A disc through hole 16-1 is provided on the first fixing disc 16. A gap is maintained between the micro-mixing nozzle 7 and the fuel nozzle 8. In this way, an air flow path is formed. After introducing external air to cool the burner head, the heated air is mixed with the fuel for combustion. As an example, the air inlet 14 is provided on the side wall of the air chamber fixing cavity 2, and a through hole is provided on the chamber plate between the air cooling chamber 1 and the air chamber fixing cavity 2 to connect the air flow path.

[0052] As an example, the center distance between the pilot combustion unit and each micro-mixing combustion unit is 65-80 mm. The spacing between the micro-mixing nozzles 7 in the micro-mixing combustion unit is 2-3.5 times the diameter of the nozzle. The diameter of the premixing micro-holes 15 is 3-8 mm, 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 25-45 mm. Centered on the pilot combustion unit, at least one or more circles of micro-mixing combustion units can be arranged evenly in the circumferential direction. When there are multiple circles, the radial distance between the adjacent two circles of micro-mixing combustion units is 65-80 mm.

[0053] The second part: A specific example

[0054] This example is a 100 kW laboratory / industrial transition-scale natural gas hydrogen-doped burner. The center distance between the pilot combustion unit and each micro-mixing combustion unit is 80 mm. The array nozzles in the micro-mixing combustion unit have 19 holes, and the swirler is composed of 8 45° helical blades. In this burner, the swirling diffusion flame undertakes 10% of the heat load demand, and 6 micro-mixing combustion units are responsible for a total heat load of 90 kW (an average of 15 kW of thermal power per unit). The equivalence ratio in the example is 0.8, and the volume mixing ratio of hydrogen reaches more than 85%.

[0055] The combustion device includes an air cooling chamber, an air storage fixing chamber, and a gas storage fixing chamber arranged successively from top to bottom. Among them, the multi-array micro-mixing nozzles with 19 holes and the fuel nozzles are uniformly arranged in a honeycomb distribution between the first fixing disk and the second fixing disk. During installation, the cooperation between the two is adjusted so that there is a gas / air premixed section of 40 - 45 mm in the micro-mixing nozzles. Each micro-mixing combustion unit is coaxially installed in the installation position formed by an independent air storage and an independent gas storage. The swirler is located at the outlet end face of the burner by adjusting the threaded rotation depth of the fixing disk.

[0056] The combustion device includes the central air (oxidant) inlet and the gas inlet of the pilot combustion unit, as well as the mixed gas inlet and the air inlet of multiple independently controlled micro-mixing combustion units. The central air and gas are ignited at the burner outlet through the central sleeve structure to form a swirling diffusion combustion flame, providing a high-temperature environment and a stable ignition source for the micro-mixing array small flame clusters. 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 storage, then flows through the air cooling chamber, and through multiple rows of air injection holes uniformly distributed on the side wall of the air cooling sleeve, flushes and cools the multi-array micro-mixing nozzles, thereby effectively cooling the burner head and preventing damage caused by high-temperature flames. After that, the air flows back to the independent air storage through the through holes in the disk, completing the top-down circular flow process. Further, the hydrogen-rich gas is ejected at a high speed in a cross-jet form through several premixing micro-holes arranged on the side wall of the fuel nozzle, collides with the air entering the multi-array micro-mixing nozzles, realizes small-scale high-intensity mixing in the premixed section, and the component mixing uniformity reaches 0.99. Finally, an ideally premixed fully developed high-speed jet is formed at the downstream burner outlet, and the mixed gas flow rate reaches 25 - 35 m / s. At this time, the premixed gas is ignited by the flame of the pilot combustion unit, and obvious entrainment effect and the trend of the flame approaching the center are observed. Finally, a spatially symmetric, uniformly stable micro-mixing multi-array small flame cluster is formed, and the outlet NOx < 30 mg / Nm 3 . This method significantly improves the combustion efficiency and stability by optimizing the flow path and mixing method of air and gas.

[0057] Verified by a large number of sufficient experiments by the inventor team, the above structural dimensions, unit quantity, power distribution, and operating condition calculation can all be adjusted according to actual needs. For example, the range of equivalence ratios applicable to the combustion device based on the design concept of the present invention includes the lean blowout limit of gas combustion to 1.2. The gas for the pilot combustion unit can be natural gas or a hydrogen-rich gas mixed with a certain proportion. The hydrogen addition ratio of the mixed gas in the micro-mixing combustion unit ranges from 20% to 100%. The number of circumferential micro-mixing combustion units can be different quantities or different numbers of rings. The number of micro-mixing array holes can be adjusted according to the actual situation. The length of the premixing section is adjusted according to the pore diameter and spacing of the premixing micropores. The center distance between the pilot / micro-mixing combustion units can be enlarged / reduced, etc.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention and their beneficial effects, and are not used as the basis for defining the scope of patent protection. On the premise of conforming to the core principle and design concept of the present invention, any improvement and optimization based on the present invention should be included in the scope of patent protection. The parameter values provided in the embodiments of the present invention are for reference only. In actual applications, the structural dimensions and combustion load can be appropriately adjusted within the allowable error range according to specific operating conditions and scenarios to optimize the specific implementation methods and performance indicators. The setting of these parameters takes into account the reasonable deviations in engineering practice and allows necessary adjustments on the premise of meeting the design requirements.

Claims

1. A swirl duty multi-element micro-mixed coupling low-nitrogen combustion device for hydrogen-blended natural gas, characterized in that: The main structure of the device comprises an air cooling chamber (1), an air bin fixing chamber (2) and a gas bin fixing chamber (3) which are arranged in a stacked manner from top to bottom; a duty combustion unit having a sleeve structure is arranged in the center of the main structure in a manner of penetrating through each chamber, comprising a coaxially arranged gas passage pipe (9) and an air sleeve (10); with the duty combustion unit as the center, mounting holes are evenly arranged circumferentially on each chamber plate in the main structure, except for the bottom chamber plate of the gas bin fixing chamber (3); annular partitions are arranged along the edges of each mounting hole in the air bin fixing chamber (2) and the gas bin fixing chamber (3), respectively forming one-to-one corresponding and connected independent air bins (5) and independent gas bins (6), thereby forming a plurality of embedded mounting positions arranged alternately in the circumferential direction; The device also includes a micro-mixing combustion unit having the same number as the embedded installation position, including an air cooling sleeve (4) and a second fixed disc (17); a combustion disc and a first fixed disc (16) are respectively arranged at the top and bottom ends of the air cooling sleeve (4), each having a plurality of through holes arranged in an array and the positions of the through holes correspond to each other; a plurality of micro-mixing nozzles (7) are arranged in an axial array inside the air cooling sleeve (4), and the two ends of the micro-mixing nozzles are respectively inserted into the through holes on the combustion disc and the first fixed disc (16); on the second fixed disc (17), a plurality of through holes are arranged in an axial array, and a single-ended closed fuel nozzle (8) is inserted into the upper end of each through hole; near the fuel nozzle On the side wall of the closed end of the tube (8), a plurality of premixing microholes (15) are evenly arranged in a circumferential direction; the closed end of the fuel nozzle (8) extends into the corresponding micromixing nozzle (7) so that the premixing microholes (15) are not exposed, and sufficient internal space is reserved in the micromixing nozzle (7) for mixing fuel and air; a plurality of micromixing 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 adapted to the corresponding installation holes on each chamber plate to achieve sealing of the independent air chamber (5) and the independent gas chamber (6); a gas inlet (13) connected to the independent gas chamber (6) is provided on the bottom chamber plate of the gas chamber fixed chamber (3); An air inlet (14) is provided on the side wall of the air cooling chamber (1), the air chamber fixed chamber (2) or the gas chamber fixed chamber (3), an air through hole is provided on the chamber plate between the corresponding chambers, a plurality of air perforations (4-1) are provided on the side wall of the air cooling sleeve (4), a disc through hole (16-1) is provided on the first fixed disc (16), and a gap is maintained between the micro-mixing nozzle (7) and the fuel nozzle (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 the fuel for combustion.

2. The device according to claim 1, characterized in that The main body of the gas storage tank fixing chamber (3) is a hollow cylindrical structure, and the edges of the upper and lower chamber plates thereof extend transversely to form an annular flange ring; the air cooling chamber (1) and the air storage tank fixing chamber (2) are both cylindrical structures with bottom openings, and the edges of the bottom opening extend transversely to form an annular flange ring; the air cooling chamber (1), the air storage tank fixing chamber (2) and the gas storage tank fixing chamber (3) are stacked in sequence, and are fastened and installed by means of bolts penetrating through the through holes on the flange rings.

3. The device according to claim 1, characterized in that A plurality of circular openings matching the shapes of the micro-mixing combustion units are respectively provided on the air cooling chamber (1), the chamber plate of the air chamber fixed chamber (2) and the upper chamber plate of the gas chamber fixed chamber (3); the micro-mixing combustion units pass through the openings from top to bottom and are seated on the lower chamber plate of the gas chamber fixed chamber (3); the gas inlet (13) is a pipe fitting passing through the lower chamber plate of the gas chamber fixed chamber (3).

4. The device according to claim 1, characterized in that In the micro-mixing combustion unit, threads are respectively arranged on the edges of the first fixed disc (16) and the second fixed disc (17), and matching threads are respectively arranged at the openings of the chamber plates corresponding to the two discs; the micro-mixing combustion unit is inserted downward into the openings of each chamber plate and is sealed and installed in a spiral manner.

5. The device according to claim 1, characterized in that An air swirler (11) is provided in the annular region between the gas duct (9) and the air sleeve (10), and is composed of a central sleeve and 8 to 12 swirl blades provided on the sleeve; the inner wall of the sleeve is provided with threads and is installed on the top of the gas duct (9) in a threaded manner, and its outer end surface is kept flush with the surface of the combustion disk; the axial angle between the swirl blade and the sleeve is in the range of 30° to 45°, and the air jet velocity is made 4 to 6 times that of the gas by setting the annular flow area of ​​the duty combustion unit and the swirl blade angle.

6. The device according to claim 1, characterized in that The number of the micro-mixing nozzles (7) is n, 7≤n≤25; the micro-mixing nozzles (7) are fixedly connected to the combustion disk and the first fixed disk (16) by welding, and the open end of the fuel nozzle (8) is fixedly connected to the second fixed disk (17) by welding; the fuel nozzle (8) and the micro-mixing nozzle (7) are fixedly connected by spaced spot welding, and sufficient air passages are reserved.

7. The device according to claim 1, characterized in that The closed end of the fuel nozzle (8) has a conical structure.

8. The device according to claim 1, characterized in that In the independent gas storehouse (6), a uniform perforated plate (12) arranged transversely is provided.

9. The device according to claim 1, characterized in that The center distance between the on-duty combustion unit and each micro-mixing combustion unit is 65 to 80 mm; the diameter of the premixing micro-mixing nozzle (7) is 3 to 8 mm, and the spacing between adjacent nozzles is 2 to 3.5 times the nozzle diameter; the diameter of the premixing micro-hole (15) is 0.5 mm, which is smaller than the quenching diameter of the fuel 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 to 45 mm.

10. The device according to claim 1, characterized in that With the on-duty combustion unit as the center, at least one circle of micro-mixed combustion units is evenly arranged circumferentially; when there are multiple circles, the radial distance between two adjacent circles of micro-mixed combustion units is 65 to 80 mm.

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