Secondary combustor and axial staged combustion chamber

Abstract

The invention relates to a two-stage combustor and an axial staged combustion chamber. The secondary combustor comprises a fuel main pipe, a fuel branch pipe, an inner cylinder and an outer cylinder; an inner airflow channel is formed between the inner cylinder and the fuel main pipe; an inner jet hole is formed in one end, close to the outlet of the inner cylinder, of the side wall of the fuel main pipe; an outer airflow channel is formed between the outer cylinder and the inner cylinder, and the outer cylinder comprises a main cylinder section and a conical cylinder section; the conical barrel section sleeves the inlet end of the inner barrel, and at least part of the conical barrel section extends into the main barrel section; the inner diameter of the conical barrel section is gradually reduced from the first end to the second end; the axial direction of the fuel branch pipe is arranged along the radial direction of the fuel main pipe, one end of the fuel branch pipe is connected to the side wall of the fuel main pipe, and the other end penetrates through the side wall of the inner cylinder and extends into the conical cylinder section; an outer jet hole is formed in the end, stretching into the conical barrel section, of the side wall of the fuel branch pipe. The secondary combustor can effectively isolate direct coupling of secondary fuel and primary flame, and avoids unstable combustion and over-high temperature caused by combustion superposition in a coupling area.

Description

Technical Field

[0001] This application relates to the field of fuel turbine technology, and in particular to two-stage combustors and axial staged combustion chambers. Background Technology

[0002] Against the backdrop of profound global energy structure transformation and stringent low-carbon policies, fuel turbine combustion technology is facing an urgent need to transition from simple high efficiency to cleaner and more intelligent processes. Compared to the single-stage combustion system used in traditional combustors, the axial staged combustor employs a two-stage combustion system. This two-stage system can construct a multi-stage combustion reaction system through staged fuel supply and dynamic control of combustion zones, achieving synergistic optimization of pollutant control and combustion efficiency. This has become a core technological pillar for the competitiveness of heavy-duty fuel turbines.

[0003] However, compared to single-stage combustion systems, two-stage combustion systems are prone to a coupling zone between the primary and secondary flames. This flame coupling can easily lead to combustion instability, and the temperature in the coupling zone is significantly higher than the average temperature inside the combustion chamber, easily resulting in the formation of large amounts of nitrogen oxides. In addition, a recirculation zone exists downstream of the secondary burner at the root of the transverse jet. The average temperature in this recirculation zone is high, easily causing erosion of the downstream combustion chamber walls, which also produces large amounts of nitrogen oxides. Summary of the Invention

[0004] Therefore, it is necessary to provide a two-stage burner and an axially staged combustion chamber to address at least one of the above-mentioned technical problems.

[0005] This application provides a two-stage burner, which includes: a fuel main pipe, a fuel branch pipe, an inner cylinder sleeved outside the fuel main pipe, and an outer cylinder sleeved outside the inner cylinder;

[0006] An internal airflow channel is formed between the inner cylinder and the fuel main pipe; an internal jet hole is provided on the side wall of the fuel main pipe at one end near the outlet of the inner cylinder.

[0007] An external airflow channel is formed between the outer cylinder and the inner cylinder. The outer cylinder includes a main cylinder section and a conical cylinder section connected to one end of the main cylinder section. The conical cylinder section is fitted onto the inlet end of the inner cylinder and extends at least partially into the interior of the main cylinder section. The conical cylinder section has a first end facing the outside of the main cylinder section and a second end located inside the main cylinder section. The inner diameter of the conical cylinder section gradually decreases from the first end to the second end.

[0008] The axial direction of the fuel branch pipe is arranged along the radial direction of the fuel main pipe. One end of the fuel branch pipe is connected to the side wall of the fuel main pipe, and the other end passes through the side wall of the inner cylinder and extends into the conical section. An external jet hole is opened on the side wall of the fuel branch pipe at the end that extends into the conical section.

[0009] In one embodiment, the secondary burner further includes a first swirler, which is disposed circumferentially around the outer peripheral surface of the sidewall of the fuel main pipe.

[0010] The position of the first cyclone separator in the axial direction of the fuel main pipe overlaps with the position of the inner jet orifice in the axial direction of the fuel main pipe, so that the first cyclone separator surrounds the inner jet orifice.

[0011] In one embodiment, the secondary burner further includes a second swirler, which is disposed circumferentially on the inner circumferential surface of the inner cylinder's sidewall.

[0012] The direction from the inlet end of the inner cylinder to the outlet end is such that the outlet end of the inner cylinder extends beyond the fuel main pipe; the second cyclone is located on the side of the fuel main pipe near the outlet end of the inner cylinder.

[0013] In one embodiment, the secondary burner further includes a third swirler, which is disposed circumferentially on the inner circumferential surface of the side wall of the main cylinder section.

[0014] The third hydrocyclone is located on the side of the conical section near the outlet end of the inner cylinder.

[0015] In one embodiment, the secondary burner further includes a gas regulating structure, which is disposed on the fuel main pipe and is used to regulate the fuel flow rate through the gas regulating structure;

[0016] Along the axial direction of the main fuel pipe, the gas regulating structure is located between the fuel branch pipe and the inner jet orifice, and is used to regulate the gas flow rate through the gas regulating structure.

[0017] In one embodiment, the secondary burner further includes an air conditioning structure, which includes multiple regulating plates, each regulating plate being connected to a conical section and respectively abutting against the inner circumferential surface of the conical section; the multiple regulating plates are arranged sequentially along the circumference of the conical section;

[0018] Each adjusting plate can be adjusted in position along the generatrix of the conical section; the end of the adjusting plate near the inner cylinder outlet extends out to the second end of the conical section.

[0019] In one embodiment, the adjusting plate is provided with a first connecting hole, and the side wall of the tapered cylindrical section is provided with a second connecting hole. The first connecting hole and the second connecting hole correspond one-to-one, and the first connecting hole and the second connecting hole are used for the connecting parts to pass through.

[0020] Among them, one of the first connecting hole and the second connecting hole is a strip hole and the other is a round hole, with the length direction of the strip hole along the generatrix direction of the tapered cylinder section.

[0021] In one embodiment, the outer cylinder further includes a gradually expanding section connected to the end of the main cylinder section away from the conical cylinder section.

[0022] In one embodiment, the outlet end of the outer cylinder extends beyond the outlet end of the inner cylinder in the direction from the inlet end to the outlet end.

[0023] In one embodiment, the outlet end of the inner cylinder has a tapered outlet structure.

[0024] This application provides an axially staged combustion chamber, including a combustion chamber body, a primary burner, and any of the secondary burners described in the above embodiments. The primary burner is installed at one end of the combustion chamber body along the axial direction, and the secondary burner is installed on one side of the combustion chamber body along the radial direction.

[0025] In the aforementioned two-stage burner and axial staged combustion chamber, a portion of the fuel in the main fuel pipe is injected into the inner airflow channel through the inner jet orifice, premixing with the air in the inner cylinder to form an inner premixed gas layer, which is then ejected from the inner cylinder outlet. Another portion of the fuel in the main fuel pipe flows to the fuel branch pipe, where the fuel ejected through the outer jet orifice enters the outer airflow channel and is located within the conical section. Because the inner diameter of the conical section gradually narrows from the first end to the second end, the air in the outer airflow channel, as it flows through the conical section, is guided by the conical section to accelerate obliquely along its sidewall, impacting the fuel ejected through the outer jet orifice and pushing it against the outer wall of the inner cylinder. This causes the fuel to flow close to the outer wall of the inner cylinder and be entrained by the high-speed outer air, forming an outer premixed gas layer where the fuel adheres to the wall and is enveloped by air. When the inner premixed gas and the outer premixed gas (i.e., the mixture of air and fuel) are jointly injected from the secondary burner, the outer premixed gas is located outside the inner premixed gas. The outer high-speed air surrounding the fuel in the outer premixed gas forms a physical barrier, which can effectively isolate the direct coupling between the secondary fuel and the primary flame, and avoid combustion instability and excessive temperature caused by the combustion superposition in the coupling zone.

[0026] Secondly, because the fuel is encased in the air of the outer premixed gas, the recirculation zone is mainly based on air circulation. As the fuel is carried by the air and flows along the direction close to the outer wall of the inner cylinder, it is difficult for it to enter the core area of ​​the recirculation zone. This can avoid the fuel concentration in the recirculation zone being too high, thereby reducing the local temperature of the recirculation zone and reducing the generation of nitrogen oxides and wall erosion. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an axially staged combustion chamber in related technologies.

[0028] Figure 2 This is a schematic diagram of the structure of a two-stage burner in one embodiment.

[0029] Figure 3 for Figure 2 A sectional view.

[0030] Figure 4 for Figure 1A schematic diagram of the secondary burner from another perspective.

[0031] Figure 5 This is a cross-sectional view of a secondary burner according to another embodiment.

[0032] Explanation of icon numbers:

[0033] 10. Combustion chamber body; 20. Primary burner; 30. Secondary burner;

[0034] 100. Fuel main pipe; 101. Internal jet orifice;

[0035] 200. Fuel branch pipe; 201. External jet orifice;

[0036] 300, Inner cylinder; 301, Inner airflow channel; 310, Outlet end of inner cylinder 310;

[0037] 400, Outer cylinder; 401, External airflow channel; 410, Main cylinder section; 420, Conical cylinder section; 420a, First end; 420b, Second end; 430, Gradually expanding cylinder section;

[0038] 500. First hydrocyclone;

[0039] 600. Second hydrocyclone;

[0040] 700. Third hydrocyclone;

[0041] 800. Gas regulation structure;

[0042] 910. Adjustment plate. Detailed Implementation

[0043] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0044] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, 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, and therefore should not be construed as a limitation of this application.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0047] 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.

[0048] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0049] refer to Figure 1 The axially staged combustion chamber in the related technology includes a combustion chamber body 10, a primary burner 20, and a secondary burner 30. The primary burner 20 is arranged at one end of the combustion chamber body 10 along the axial direction ZZ'. Along the flow direction of the mainstream airflow (including air, fuel, and combustion products) within the combustion chamber body 10 (… Figure 1 (roughly in the OZ' direction), the secondary burner 30 is arranged downstream of the combustion chamber body 10, and the secondary burner 30 is located on one side of the combustion chamber body 10 along the radial XX' direction.

[0050] There is also a transverse jet within the combustion chamber body 10, with the flow direction roughly along the radial direction XX' of the combustion chamber body 10. The mainstream airflow mainly originates from the products formed after the combustion of fuel and air injected by the first-stage burner 20, as well as the unreacted mixture, while the transverse jet mainly originates from the mixture of fuel and air injected by the second-stage burner 30.

[0051] like Figure 1 As shown, a flame coupling zone exists near the primary and secondary flame regions. This coupling can easily lead to combustion instability, and the temperature in the coupling zone is significantly higher than the average temperature within the combustion chamber, making it prone to generating large amounts of nitrogen oxides. Downstream of the transverse jet along the direction of the mainstream airflow, a recirculation zone also exists. The airflow in this recirculation zone is slow, and the average temperature is high, which can easily cause erosion of the downstream combustion chamber walls and also generate large amounts of nitrogen oxides.

[0052] Please combine Figure 2 and Figure 3 One embodiment of this application provides a two-stage burner. The two-stage burner includes: a fuel main pipe 100, a fuel branch pipe 200, an inner cylinder 300 sleeved outside the fuel main pipe 100, and an outer cylinder 400 sleeved outside the inner cylinder 300.

[0053] An internal airflow channel 301 is formed between the inner cylinder 300 and the fuel main pipe 100. An internal jet hole 101 is provided on the side wall of the fuel main pipe 100 at the end near the outlet of the inner cylinder 300.

[0054] Optionally, there may be multiple internal jet holes 101, which are evenly spaced along the circumference of the fuel main pipe 100, for example, 8 to 116, and the diameter of the internal jet holes 101 is 3 mm to 106 mm.

[0055] An external airflow channel 401 is formed between the outer cylinder 400 and the inner cylinder 300. The outer cylinder 400 includes a main cylinder section 410 and a tapered cylinder section 420 connected to one end of the main cylinder section 410. The tapered cylinder section 420 is fitted onto the inlet end of the inner cylinder 300 and extends at least partially into the interior of the main cylinder section 410. The tapered cylinder section 420 has a first end 420a facing outward from the main cylinder section 410 and a second end 420b located inside the main cylinder section 410. The inner diameter of the tapered cylinder section 420 gradually decreases from the first end 420a to the second end 420b. The first end 420a of the tapered cylinder section 420 may be located outside the main cylinder section 410.

[0056] Optionally, there can be multiple fuel branch pipes 200, which are evenly spaced along the axial direction of the fuel main pipe 100, for example, 6, 7 or 8.

[0057] The fuel branch pipe 200 is arranged axially along the radial direction of the fuel main pipe 100. One end of the fuel branch pipe 200 is connected to the side wall of the fuel main pipe 100, and the other end passes through the side wall of the inner cylinder 300 and extends into the conical section 420. The side wall of the fuel branch pipe 200 has an external jet hole 201 at the end that extends into the conical section 420.

[0058] Optionally, there may be multiple external jet holes 201, with the same number of external jet holes 201 on each fuel branch pipe 200. The total number of external jet holes 201 may be, for example, 10 to 40, and the diameter of the external jet holes 201 may be 1.5 mm to 6 mm.

[0059] When in use, the secondary burner is connected to the air supply system and the fuel supply system. The air supply system simultaneously supplies combustion air to the inner airflow passage 301 and the outer airflow passage 401, and the fuel supply system supplies fuel to the fuel main pipe 100.

[0060] Since an internal airflow channel 301 is formed between the inner cylinder 300 and the fuel main pipe 100, and an internal jet hole 101 is provided on the side wall of the fuel main pipe 100 at one end near the outlet of the inner cylinder 300, a portion of the fuel in the fuel main pipe 100 is ejected through the internal jet hole 101 and enters the internal airflow channel 301, where it is premixed with the air in the internal airflow channel 301 to form an inner premixed gas, which is then ejected from the outlet of the inner cylinder 300.

[0061] One end of the fuel branch pipe 200 is connected to the side wall of the fuel main pipe 100, and the other end of the fuel branch pipe 200 is connected to the interior of the fuel main pipe 100. In this way, another part of the fuel in the fuel main pipe 100 can flow to the fuel branch pipe 200 and be ejected through the external jet hole 201 on the fuel branch pipe 200.

[0062] Since the external jet orifice 201 is located at one end of the side wall of the fuel branch pipe 200 that extends into the conical section 420, that is, the external jet orifice 201 is located between the side wall of the conical section 420 and the side wall of the inner cylinder 300, that is, within the external airflow channel 401, the fuel ejected through the external jet orifice 201 on the fuel branch pipe 200 enters the external airflow channel 401.

[0063] Since the inner diameter of the conical section 420 gradually narrows from the first end 420a to the second end 420b, when the air in the outer airflow channel 401 flows through the conical section 420, the conical section 420 can guide the air to flow obliquely and accelerate along the side wall of the conical section 420 and impact the fuel ejected from the outer jet hole 201, pushing the fuel towards the outer wall of the inner cylinder 300. This causes the fuel to flow close to the outer wall of the inner cylinder 300 and be entrained by the high-speed air in the outer layer, thus forming an outer premixed gas layer in which the fuel adheres to the wall and the air envelops the fuel.

[0064] When the aforementioned two-stage burner is applied in an axially staged combustion chamber, a portion of the fuel in the fuel main pipe 100 can be injected into the inner airflow channel 301 through the inner jet orifice 101, premixed with the air in the inner cylinder 300 to form an inner premixed gas, which is then ejected from the outlet of the inner cylinder 300. Another portion of the fuel in the fuel main pipe 100 can flow to the fuel branch pipe 200, and the fuel ejected through the outer jet orifice 201 on the fuel branch pipe 200 enters the outer airflow channel 401 and is located in the conical section 420. Because the inner diameter of the conical section 420 gradually narrows from the first end 420a to the second end 420b, when the air in the outer airflow channel 401 flows through the conical section 420, the conical section 420 guides the air to accelerate obliquely along the side wall of the conical section 420 and impact the fuel ejected from the outer jet hole 201, pushing the fuel towards the outer wall of the inner cylinder 300. This causes the fuel to flow close to the outer wall of the inner cylinder 300 and be entrained by the high-speed air in the outer layer, forming an outer premixed gas layer where the fuel adheres to the wall and the air envelops the fuel. When the inner and outer premixed gases (i.e., the mixture of air and fuel) are ejected together from the secondary burner, the outer premixed gas layer is located outside the inner premixed gas layer. The high-speed air in the outer premixed gas layer enveloping the fuel forms a physical barrier, which can effectively isolate the direct coupling between the secondary fuel and the primary flame, avoiding combustion instability and excessively high temperature caused by the combustion superposition in the coupling zone.

[0065] Secondly, because the fuel is encased in the air of the outer premixed gas, the recirculation zone is mainly based on air circulation. As the fuel is carried by the air and flows along the direction close to the outer wall of the inner cylinder 300, it is difficult for it to enter the core area of ​​the recirculation zone. This can avoid the fuel concentration in the recirculation zone being too high, thereby reducing the local temperature of the recirculation zone and reducing the generation of nitrogen oxides and wall erosion.

[0066] The inner premixed gas and the outer premixed gas (i.e., the mixture of air and fuel) are jointly injected from the secondary burner. The inner premixed gas is located in the center of the secondary combustion zone compared to the outer premixed gas, which is used to ensure the stability and combustion efficiency of the secondary flame.

[0067] Specifically, by adjusting the fuel ratio entering the inner airflow channel 301 and the outer airflow channel 401, more fuel enters the inner airflow channel 301, resulting in a fuel-rich inner premixed gas and less fuel entering the outer airflow channel 401. The fuel-rich inner premixed gas, located in the center of the secondary combustion zone, provides a stable energy core and ignition basis for the secondary flame, ensuring combustion stability and efficiency. The lower fuel ratio and higher air ratio in the outer airflow channel 401 not only facilitate the formation of an outer airflow pattern where fuel adheres to the wall and is enveloped by air, but also create a concentration gradient between the inner and outer premixed gases from the inside out. This allows the combustion of the inner premixed gas to orderly ignite the fuel in the outer premixed gas, promoting efficient combustion of the fuel in the outer premixed gas.

[0068] Please combine Figures 2 to 4 In some embodiments, the secondary burner further includes a first swirler 500, which is disposed circumferentially around the outer peripheral surface of the sidewall of the fuel main pipe 100.

[0069] The position of the first swirler 500 in the axial direction of the fuel main pipe 100 overlaps with the position of the inner jet orifice 101 in the axial direction of the fuel main pipe 100, so that the first swirler 500 surrounds the inner jet orifice 101.

[0070] In this embodiment, since the first swirler 500 surrounds the inner jet orifice 101, after the fuel is injected into the inner airflow channel 301 through the inner jet orifice 101, the swirling action generated by the first swirler 500 allows the fuel ejected from the inner jet orifice 101 to be fully mixed with the air, rapidly improving the uniformity of fuel-air mixing in the inner premixed gas. By improving the uniformity of fuel-air mixing in the inner premixed gas, on the one hand, it can avoid the high temperature caused by local combustion enrichment, thereby helping to reduce the secondary flame temperature and reduce nitrogen oxide generation; on the other hand, the uniform mixing of fuel and air can also improve the stability of secondary flame combustion.

[0071] Optionally, the first hydrocyclone 500 includes a plurality of blades arranged at circumferential intervals, for example, 6 to 12. The swirling angle of the blades of the first hydrocyclone 500 is 30° to 45°.

[0072] Please combine Figures 2 to 4 In some embodiments, the secondary burner further includes a second swirler 600, which is disposed circumferentially on the inner circumferential surface of the side wall of the inner cylinder 300.

[0073] From the inlet end of the inner cylinder 300 to the outlet end, the outlet end 310 of the inner cylinder 300 extends beyond the fuel main pipe 100. The second cyclone 600 is located on the side of the first cyclone 500 near the outlet end 310 of the inner cylinder 300, that is, along the axial direction of the inner cylinder 300, and there is a gap between the second cyclone 600 and the first cyclone 500.

[0074] In this embodiment, the fuel ejected from the inner jet orifice 101 on the fuel main pipe 100 is initially mixed with air under the action of the first swirler 500. Since the outlet end 310 of the inner cylinder 300 extends beyond the fuel main pipe 100, and the second swirler 600 is located on the side of the first swirler 500 near the outlet end 310 of the inner cylinder 300, the fuel and air are initially mixed by the first swirler 500 before flowing through the second swirler 600. The second swirler 600 promotes further and more thorough mixing of fuel and air through swirling action, thereby further improving the uniformity of fuel-air mixing in the inner premixed gas, which in turn further reduces the secondary flame temperature to reduce nitrogen oxide generation and improves the stability of secondary flame combustion.

[0075] Furthermore, the first swirler 500 and the inner circumferential surface of the side wall of the inner cylinder 300 are spaced apart, forming an annular space between them. The second swirler 600 is also positioned circumferentially on the inner circumferential surface of the side wall of the inner cylinder 300, and is located on the side of the first swirler 500 near the outlet end 310 of the inner cylinder 300. In other words, the second swirler 600 is located downstream of this annular space. Therefore, the second swirler 600 not only swirls the air flowing through this annular space, promoting thorough mixing of this air with fuel to improve uniformity, but more importantly, driven by the swirling motion of the second swirler 600, the inner premixed gas flowing out from the outlet end 310 of the inner cylinder 300 will generate a certain rotational flow direction. This effectively prevents the inner premixed gas in the transverse jet from directly impacting the wall of the combustion chamber body opposite the secondary burner, allowing it to more easily integrate into the mainstream airflow and flow axially along the combustion chamber body 10 with the mainstream airflow.

[0076] Furthermore, the second cyclone separator 600 can be set at the outlet end 310 of the inner cylinder 300, that is, when the inner premixed gas flows out from the outlet end 310 of the inner cylinder 300, it can generate a certain rotational flow direction under the cyclone drive of the second cyclone separator 600.

[0077] Furthermore, along the axial direction of the inner cylinder 300, the outlet end of the second cyclone separator 600 does not extend beyond the outlet end 310 of the inner cylinder 300, so as to avoid the second cyclone separator 600 causing additional disturbance to the airflow pattern of the outer layer premixed gas outside the inner cylinder 300.

[0078] Optionally, the second cyclone 600 includes a plurality of blades arranged at circumferential intervals, for example, 8 to 16 blades. The swirl angle of the blades of the second cyclone 600 is 10° to 35°.

[0079] It should be noted that the swirl angle of the blades of the first swirler 500 is greater than that of the blades of the second swirler 600. The main function of the first swirler 500 is to uniformly mix the fuel and air within the inner airflow channel 301; a larger swirl angle facilitates rapid and uniform mixing of the fuel and air. The second swirler 600 is used to create a slight swirling flow of the inner premixed gas flowing out from the outlet end 310 of the inner cylinder 300. This prevents the inner premixed gas in the transverse jet from directly impacting the wall of the combustion chamber body opposite the secondary burner, allowing it to more easily integrate into the mainstream airflow and flow axially along the combustion chamber body 10 with the mainstream airflow. Therefore, the swirl angle of the blades of the second swirler 600 does not need to be too large.

[0080] Please combine Figures 2 to 4 In some embodiments, the secondary burner further includes a third swirler 700, which is disposed circumferentially on the inner circumferential surface of the side wall of the main cylinder section 410.

[0081] The third hydrocyclone 700 is located on the side of the conical section 420 near the outlet end 310 of the inner cylinder 300. Specifically, there is a gap between the third hydrocyclone 700 and the conical section 420 along the axial direction of the outer cylinder 400.

[0082] Since the external jet orifice 201 is located on the side wall of the fuel branch pipe 200, it penetrates the side wall of the fuel branch pipe 200 radially. When fuel is ejected through the external jet orifice 201, it is also ejected radially through the fuel branch pipe 200. When the conical section 420 guides the air to accelerate obliquely along its side wall, the flow direction intersects with the flow direction of the fuel ejected through the external jet orifice 201. Therefore, the high-speed air can impact the fuel ejected through the external jet orifice 201, thereby achieving premixing of air and fuel and forming an outer premixed gas layer where "fuel flows along the wall and air envelops the fuel."

[0083] Since the third cyclone separator 700 is located on the side of the conical section 420 near the outlet end 310 of the inner cylinder 300, that is, the third cyclone separator 700 is located in the downstream region of the conical section 420, the third cyclone separator 700 can, through swirling action, promote further appropriate mixing of fuel and air in the outer premixed gas layer where "fuel flows along the wall and air envelops fuel," allowing the fuel to diffuse appropriately outward, optimizing the fuel concentration distribution gradient, and avoiding excessive fuel accumulation on the outer wall of the inner cylinder 300, which would lead to localized high temperatures.

[0084] Meanwhile, since the third swirler 700 is arranged circumferentially along the inner circumferential surface of the side wall of the main cylinder section 410, the swirling effect of the third swirler 700 can guide the outer premixed gas to expand appropriately outward along the radial direction of the outer cylinder 400, thereby increasing the area of ​​the secondary flame to reduce the local temperature.

[0085] Furthermore, the third swirler 700 can guide the outer premixed gas to generate a certain rotational flow direction, so that the flow direction of the outer premixed gas when it flows out of the outer cylinder 400 has a certain rotation. This can effectively prevent the outer premixed gas in the transverse jet from directly impacting the wall surface of the combustion chamber body opposite to the secondary burner. Instead, it is easier to integrate into the mainstream airflow and flow along the axial direction of the combustion chamber body 10 with the mainstream airflow.

[0086] Furthermore, along the axial direction of the inner cylinder 300, the outlet end of the third cyclone separator 700 does not exceed the outlet end 310 of the inner cylinder 300, and the location of the third cyclone separator 700 surrounds the second cyclone separator 600. In this way, when the outer layer premixed gas flows out from the outlet end of the third cyclone separator 700, it has not yet merged with the inner layer premixed gas, thereby ensuring that the outer layer premixed gas completes the cyclone regulation driven by the third cyclone separator 700 before merging with the inner layer premixed gas. This allows the outer layer premixed gas and the inner layer premixed gas to undergo natural diffusion and be properly mixed after completing the cyclone regulation.

[0087] Optionally, the third cyclone 700 includes a plurality of blades arranged circumferentially at intervals, for example, 8 to 16. The swirl angle of the blades of the second cyclone 600 is 10° to 35°.

[0088] It should be noted that the swirl angle of the blades of the first swirler 500 is greater than that of the blades of the third swirler 700. The main function of the first swirler 500 is to uniformly mix the fuel and air within the inner airflow channel 301; a larger swirl angle facilitates rapid and uniform mixing of fuel and air. The third swirler 700 is used to appropriately diffuse the fuel in the outer premixed gas, optimizing the fuel concentration distribution gradient, and to create a slight rotating flow in the outer premixed gas, preventing the outer premixed gas in the transverse jet from directly impacting the wall of the combustion chamber body opposite the secondary burner. Therefore, based on the function of the third swirler 700, the swirl angle of its blades does not need to be excessively large.

[0089] Please combine Figures 2 to 4 In some embodiments, the outlet end 310 of the inner cylinder 300 has a tapered outlet structure. This tapered outlet structure allows the inner premixed gas to be moderately accelerated when it is ejected from the outlet end 310 of the inner cylinder 300, so that the inner premixed gas and the outer premixed gas will not mix too early. This ensures that the inner premixed gas can still maintain a fully mixed state in the early stage when it is ejected from the outlet end 310 of the inner cylinder 300, while the outer premixed gas can maintain the state of "air-encased fuel". This avoids the destruction of the layered structure due to premature mixing and ensures efficient combustion in the later stage.

[0090] Please combine Figures 2 to 4 In some embodiments, the outlet end of the outer cylinder 400 extends beyond the outlet end 310 of the inner cylinder 300 in the direction from the inlet end to the outlet end of the outer cylinder 400.

[0091] Thus, after the inner premixed gas is ejected from the outlet end 310 of the inner cylinder 300, it still needs to travel a certain distance before it can be ejected from the outlet end of the outer cylinder 400. During the process of the inner premixed gas flowing from the outlet end 310 of the inner cylinder 300 to the outlet end of the outer cylinder 400, the inner and outer premixed gases can naturally diffuse and mix appropriately at their interface, achieving a continuous gradient change in fuel concentration in the interface region. This avoids combustion instability caused by abrupt changes in fuel concentration at the interface region, and also maintains the isolation effect of the "air-encased fuel" structure of the outer premixed gas through gradual mixing.

[0092] Please combine Figures 2 to 4 In some embodiments, the outer cylinder 400 further includes a gradually expanding cylinder section 430, which is connected to the end of the main cylinder section 410 away from the conical cylinder section 420.

[0093] From the inlet end of the outer cylinder 400 towards the outlet end, the inner diameter of the diffuser section 430 gradually increases. Therefore, the velocity of the outer premixed gas as it exits the diffuser section 430 is reduced to a certain extent. This prevents the outer premixed gas in the transverse jet ejected from the secondary burner from directly impacting the wall of the combustion chamber body opposite the secondary burner, allowing it to flow more easily along the axial direction of the combustion chamber body 10 with the mainstream airflow. Furthermore, the gradually increasing inner diameter of the diffuser section 430 guides the outer premixed gas to expand appropriately outward, thereby increasing the area of ​​the secondary flame and reducing localized temperatures.

[0094] In addition, the smooth transition design of the diffuser section 430 ensures that the outer premixed gas maintains the basic structure of "air-encased fuel" during expansion and deceleration, which not only maintains the isolation barrier function for the primary flame, but also provides a stable flow field for the gradual mixing with the inner premixed gas.

[0095] Please refer to Figure 5 In another embodiment, the secondary burner further includes a gas regulating structure 800 disposed on the fuel main pipe 100.

[0096] Along the axial direction of the fuel main pipe 100, the gas regulating structure 800 is located between the fuel branch pipe 200 and the inner jet hole 101, and is used to regulate the gas flow rate through the gas regulating structure 800.

[0097] The function of the gas regulating structure 800 is to optimize the adaptability of the "air-enclosed fuel" structure by adjusting the fuel distribution ratio between the inner and outer airflow channels. Specifically, the gas regulating structure 800 is located between the fuel branch pipe 200 and the inner jet orifice 101. When fuel flows in from the upstream of the fuel main pipe 100, with the total fuel flow rate into the fuel main pipe 100 remaining constant, the flow rate of the fuel flowing through the gas regulating structure 800 can be adjusted to regulate the fuel ratio flowing to the inner jet orifice 101 and the fuel branch pipe 200 (i.e., flowing to the outer jet orifice 201). In this way, on the one hand, it can ensure that more fuel enters the inner airflow channel 301, maintaining a reasonable fuel concentration in the inner premixed gas to ensure the combustion stability and efficiency of the inner premixed gas; on the other hand, it can limit the amount of fuel flowing to the fuel branch pipe 200 (ultimately entering the outer airflow channel 401 through the outer jet orifice 201), avoiding excessive outer fuel from damaging the air-enclosed effect.

[0098] Furthermore, by dynamically adjusting the fuel ratio, it is possible to accurately and flexibly adapt to the requirements of different combustion conditions regarding flame shape, coupling zone isolation, and recirculation zone temperature.

[0099] In some embodiments, the gas regulating structure 800 can be a butterfly valve disposed on the fuel main pipe 100. The opening degree of the butterfly valve can be precisely controlled by a servo motor, thereby regulating the flow rate of fuel flowing through the butterfly valve, that is, regulating the fuel distribution ratio of the inner and outer airflow channels. Specifically, if the butterfly valve opening degree is increased, the flow rate of fuel flowing through the butterfly valve increases. Since the butterfly valve is located between the fuel branch pipe 200 and the inner jet orifice 101, more fuel will preferentially flow to the inner jet orifice 101 and enter the inner airflow channel 301, thereby increasing the fuel proportion of the inner premixed gas accordingly. Conversely, if the butterfly valve opening degree is decreased, the flow rate of fuel flowing through the butterfly valve decreases, the fuel proportion flowing to the inner jet orifice 101 decreases, and more fuel will flow through the fuel branch pipe 200 to the outer jet orifice 201 and enter the outer airflow channel 401. This butterfly valve regulation method controlled by a servo motor can respond precisely, flexibly, and in real time to changes in combustion conditions.

[0100] Specifically, a butterfly valve includes a valve body, a valve stem, and a valve plate. The valve plate is located inside the valve body, while the valve stem is located entirely outside the valve body, with one end of the valve stem connected to the valve plate.

[0101] The fuel main pipe is divided into two parts at the installation position of the butterfly valve. The butterfly valve is located between these two parts, and the two axial ends of the butterfly valve body are respectively sealed to these two parts of the fuel main pipe, so that the butterfly valve is connected in series in the fuel main pipe and becomes part of the fuel main pipe.

[0102] A servo motor is rigidly mounted on the butterfly valve body via a bracket. The output of the servo motor can be connected to the valve stem of the butterfly valve via a coupling and / or a reducer. Driven by the servo motor, the transmission component rotates the valve stem, which in turn rotates the valve plate within the valve body, achieving precise control of fuel flow. The rotation angle (opening degree) of the valve plate determines the fuel flow rate through the butterfly valve body.

[0103] refer to Figure 5 In some embodiments, the secondary burner further includes an air conditioning structure comprising multiple adjusting plates 910, each adjusting plate 910 being connected to and abutting the inner circumferential surface of the conical section 420. The multiple adjusting plates 910 are arranged sequentially along the circumference of the conical section 420. Each adjusting plate 910 is adjustable in position along the generatrix of the conical section 420. One end of the adjusting plate 910 near the outlet of the inner cylinder 300 extends beyond the second end 420b of the conical section 420.

[0104] Since the adjusting plates 910 are arranged circumferentially along the conical section 420 and fit against its inner circumferential surface, each adjusting plate 910 can move along the generatrix direction of the conical section 420 (i.e., the inclined direction from the first end 420a to the second end 420b), and the end of each adjusting plate 910 near the outlet of the inner cylinder 300 always extends beyond the second end 420b of the conical section. In this way, when the position of each adjusting plate 910 is adjusted along the generatrix direction of the conical section 420, the effective flow area of ​​the airflow in the external airflow channel 401 when flowing through the multiple adjusting plates 910 can be changed. For example, when each regulating plate 910 moves towards the side closer to the outlet of the inner cylinder 300 along the generatrix of the conical section 420, the regulating plates 910 move closer to each other radially within the inner cylinder 300. This reduces the flow area of ​​the channel formed by the multiple regulating plates 910, increases the airflow velocity due to the throttling effect, and enhances the impact mixing capacity of the air on the fuel in the outer airflow channel 401, thus pressing the fuel more tightly against the outer wall of the inner cylinder 300. Conversely, when each regulating plate 910 moves away from the outlet of the inner cylinder 300 along the generatrix of the conical section 420, the regulating plates 910 expand towards each other radially within the inner cylinder 300. This increases the flow area of ​​the channel formed by the multiple regulating plates 910, relatively reduces the airflow velocity, weakens the impact force of the air on the fuel in the outer airflow channel 401, reduces the mixing capacity of the air and fuel, loosens the air's envelopment of the fuel, and makes the fuel less tightly adhered to the wall during flow.

[0105] In this embodiment, the air velocity in the external airflow channel 401 is controlled by the radial contraction or expansion of each adjustment plate 910, thereby more accurately and flexibly adjusting the degree of air envelopment and mixing with the fuel. This enables the secondary burner to precisely match the degree of air envelopment and mixing with the fuel according to different operating conditions, ensuring the stability of the "air-enveloped fuel" structure and optimizing the overall combustion efficiency.

[0106] It should be noted that the inner circumferential surface of the conical cylindrical section 420 is a conical surface with an inner diameter that gradually decreases from the first end 420a to the second end 420b. The generatrix of the conical surface refers to the inclined straight line from the cone apex (located on the extension line of the second end 420b) to the cone bottom (the first end 420a). Different circumferential positions of the conical surface correspond to different generatrixes. These generatrixes are distributed radially with the central axis of the conical cylindrical section 420 as the center. Therefore, the extension directions of these generatrixes are different from each other.

[0107] Understandably, when each adjusting plate 910 is installed on the inner circumferential surface of the conical cylindrical section 420, the length direction of each adjusting plate 910 is basically consistent with the generatrix direction corresponding to its installation position on the inner circumferential surface of the conical cylindrical section 420. When each adjusting plate 910 adjusts its position along the generatrix direction of the conical cylindrical section 420, the direction of movement of the adjusting plate 910 is also basically consistent with the generatrix direction corresponding to its installation position on the inner circumferential surface of the conical cylindrical section 420. In this way, it can be ensured that when each adjusting plate 910 adjusts its position along its corresponding generatrix direction, each adjusting plate 910 can move closer to the center of the conical cylindrical section 420 or expand away from the center of the conical cylindrical section 420, thereby changing the flow area of ​​the annular channel formed by the multiple adjusting plates 910.

[0108] In one embodiment, the adjusting plate 910 is provided with a first connecting hole, and the side wall of the tapered cylindrical section 420 is provided with a second connecting hole, with the first connecting hole and the second connecting hole corresponding to each other. The first connecting hole and the second connecting hole are used for corresponding connecting parts to pass through, so as to fix the adjusting plate 910 and the side wall of the tapered cylindrical section 420.

[0109] Among them, one of the first connecting hole and the second connecting hole is a strip hole and the other is a round hole. The length direction of the strip hole is along the generatrix direction of the tapered cylinder section 420.

[0110] Specifically, the first connecting hole can be a strip-shaped hole and the second connecting hole can be a round hole; alternatively, the first connecting hole can be a round hole and the second connecting hole can be a strip-shaped hole. Understandably, the length direction of the strip-shaped hole is consistent with the length direction of the corresponding adjusting plate 910, and also consistent with the direction of movement of the corresponding adjusting plate 910 when in the adjusted position.

[0111] The first connecting hole on the adjusting plate 910 corresponds one-to-one with the second connecting hole on the side wall of the conical section 420. During assembly, corresponding connectors (e.g., bolts) are also required. Each connector passes through the corresponding first and second connecting holes to fix the corresponding adjusting plate 910 to the side wall of the conical section 420. When it is necessary to adjust the airflow rate, the connectors are loosened, and each adjusting plate 910 can move along the generatrix of the conical section 420. After adjustment, the adjusting plate 910 is fixed to the conical section 420 by the connectors passing through the corresponding positions of the round holes and the strip holes, thus locking the adjusting plate 910 in the adjusted position.

[0112] In this embodiment, the air velocity in the external airflow channel 401 is controlled by the combination of the strip hole and the round hole between the regulating plate 910 and the conical cylinder section 420. This design allows the regulating plate 910 to move flexibly along the generatrix direction, precisely and flexibly adjusting the degree of air envelopment and mixing with the fuel, while also reliably fixing the position of the regulating plate 910 to ensure that the air conditioning structure is firmly positioned under different operating conditions.

[0113] An embodiment of this application also provides an axially staged combustion chamber, which includes a combustion chamber body, a primary burner, and a secondary burner as described in any of the above embodiments. The primary burner is installed at one end of the combustion chamber body along the axial direction, and the secondary burner is installed on one side of the combustion chamber body along the radial direction.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A two-stage burner, characterized in that, The secondary burner includes: a fuel main pipe, a fuel branch pipe, an inner cylinder sleeved outside the fuel main pipe, and an outer cylinder sleeved outside the inner cylinder; An internal airflow channel is formed between the inner cylinder and the fuel main pipe; an internal jet hole is provided on the side wall of the fuel main pipe at one end near the outlet of the inner cylinder. An external airflow channel is formed between the outer cylinder and the inner cylinder. The outer cylinder includes a main cylinder section and a conical cylinder section connected to one end of the main cylinder section. The conical cylinder section is sleeved on the inlet end of the inner cylinder and extends at least partially into the interior of the main cylinder section. The conical cylinder section has a first end facing the outside of the main cylinder section and a second end located inside the main cylinder section. The inner diameter of the conical cylinder section gradually decreases from the first end to the second end. The axial direction of the fuel branch pipe is arranged along the radial direction of the fuel main pipe. One end of the fuel branch pipe is connected to the side wall of the fuel main pipe, and the other end passes through the side wall of the inner cylinder and extends into the conical section. An external jet hole is provided on the side wall of the fuel branch pipe at the end that extends into the conical section.

2. The secondary burner according to claim 1, characterized in that, The secondary burner also includes a first swirler, which is arranged circumferentially around the outer peripheral surface of the sidewall of the fuel main pipe. The first swirler is positioned axially on the fuel main pipe and the inner jet orifice is positioned axially on the fuel main pipe, such that the first swirler surrounds the inner jet orifice.

3. The secondary burner according to claim 2, characterized in that, The secondary burner also includes a second swirler, which is disposed circumferentially on the inner circumferential surface of the side wall of the inner cylinder. The outlet end of the inner cylinder extends beyond the fuel main pipe in the direction from the inlet end to the outlet end; the second cyclone separator is located on the side of the fuel main pipe near the outlet end of the inner cylinder.

4. The secondary burner according to claim 2, characterized in that, The secondary burner also includes a third swirler, which is arranged circumferentially on the inner circumferential surface of the side wall of the main cylinder section. The third cyclone separator is located on the side of the conical section near the outlet end of the inner cylinder.

5. The secondary burner according to claim 1, characterized in that, The secondary burner also includes a gas regulating structure, which is disposed on the fuel main pipe and is used to regulate the fuel flow rate through the gas regulating structure; Along the axial direction of the main fuel pipe, the gas regulating structure is located between the fuel branch pipe and the inner jet orifice, and is used to regulate the gas flow rate through the gas regulating structure.

6. The secondary burner according to claim 1, characterized in that, The secondary burner also includes an air conditioning structure, which includes multiple regulating plates. Each regulating plate is connected to the conical section and is in contact with the inner circumferential surface of the conical section. The multiple regulating plates are arranged sequentially along the circumference of the conical section. Each of the adjusting plates can be adjusted in position along the generatrix of the conical cylinder section; one end of the adjusting plate near the inner cylinder outlet extends out of the second end of the conical cylinder section.

7. The secondary burner according to claim 6, characterized in that, The adjusting plate is provided with a first connecting hole, and the side wall of the tapered cylindrical section is provided with a second connecting hole. The first connecting hole and the second connecting hole correspond one-to-one, and the first connecting hole and the second connecting hole are used for the connecting parts to pass through. Among them, one of the first connecting hole and the second connecting hole is a strip hole and the other is a round hole, and the length direction of the strip hole is along the generatrix direction of the tapered cylinder section.

8. The secondary burner according to claim 1, characterized in that, The outer cylinder further includes a gradually expanding section, which is connected to the end of the main cylinder section away from the conical cylinder section; and / or The outlet end of the inner cylinder has a tapered outlet structure.

9. The secondary burner according to claim 1, characterized in that, From the inlet end of the outer cylinder to the outlet end, the outlet end of the outer cylinder extends beyond the outlet end of the inner cylinder.

10. An axially staged combustion chamber, characterized in that, It includes a combustion chamber body, a primary burner, and a secondary burner as described in any one of claims 1-9, wherein the primary burner is installed at one end of the combustion chamber body along the axial direction, and the secondary burner is installed on one side of the combustion chamber body along the radial direction.

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