Heavy-duty gas turbine and method of using same

Abstract

This application discloses a heavy-duty gas turbine and its method of use, relating to the field of gas turbine technology. The heavy-duty gas turbine includes a combustion chamber; the combustion chamber includes a first and a second diversion pipe disposed within the inner casing. The first and second diversion pipes sequentially divide the interior of the inner casing from the edge to the center, forming a first airflow channel, a second airflow channel, and a third airflow channel. By configuring the first, second, and third airflow channels, this application precisely diverts the air entering the inner casing into three streams. The second airflow channel forms an intermediate air isolation layer, which not only avoids excessively high local temperature gradients caused by direct contact between the central combustion zone and the edge combustion zone, but also gradually dilutes the high-temperature flue gas in the center during the latter half of the combustion reaction, thus inhibiting the formation of nitrogen oxides from the reaction mechanism level.

Description

Technical Field

[0001] This application relates to the field of gas turbine technology, specifically to a heavy-duty gas turbine and its usage method. Background Technology

[0002] Lean premixed combustion is currently the mainstream low-emission combustion technology in the field of heavy-duty gas turbines. Its core principle is to pre-mix fuel and air thoroughly before they enter the combustion chamber, forming a homogeneous mixture with excess air and lean fuel before combustion. This technology can, on the one hand, reduce the overall flame combustion temperature through the dilution effect of excess air, and on the other hand, eliminate localized overheating caused by excessively rich fuel in the combustion chamber through the uniform distribution of the mixture. It is well known that in gas turbines, the higher the combustion temperature (generally exceeding 1800K), the higher the concentration of pollutants formed during combustion (i.e., nitrogen oxides). In other words, lean premixed combustion technology can effectively suppress the formation of nitrogen oxides and other combustion pollutants at the reaction mechanism level.

[0003] Figure 1 This is a schematic diagram of a heavy-duty gas turbine combustor structure based on lean premixed combustion technology in the prior art. Figure 1 As shown, the combustion chamber mainly consists of an outer casing, an inner casing, and nozzles, with an air passage formed between the outer and inner casings. Air from the heavy-duty gas turbine compressor can pass through this air passage along a designed path (i.e., Figure 1 Path A) enters the inner casing to participate in combustion. For example... Figure 1 As shown, the nozzle comprises a premixed combustion nozzle and a diffusion combustion nozzle, wherein the length of the premixed combustion nozzle is significantly shorter than that of the diffusion combustion nozzle.

[0004] During use, because the premixed combustion nozzle is relatively short, the fuel ejected from the premixed combustion nozzle can be fully premixed with the air inside the inner casing to form a mixture before participating in combustion, resulting in a combustion product such as... Figure 1 The edge combustion zone is shown; however, the diffusion combustion nozzle is longer, so the fuel ejected from the diffusion combustion nozzle directly diffuses and burns within the inner casing, forming a combustion zone as shown. Figure 1 The central combustion zone is shown.

[0005] It is important to note that the operating condition of a gas turbine is positively correlated with the amount of fuel injected into the combustion chamber through the nozzles. In other words, to improve the operating condition of the gas turbine, the amount of fuel injected into the combustion chamber through the nozzles needs to be increased. As mentioned earlier, Figure 1The heavy-duty gas turbine shown features diffusion combustion of fuel ejected from its diffusion combustion nozzle within the combustion chamber. This means that to increase the turbine's operating speed to higher levels, the fuel injection rate from the diffusion combustion nozzle must be significantly increased. Diffusion combustion involves the simultaneous mixing and combustion of fuel and air, making it impossible to pre-form a uniform lean mixture. With increased fuel quantity, insufficient air-fuel mixing occurs in the central combustion zone of this heavy-duty gas turbine, resulting in numerous locally rich fuel regions where combustion temperatures exceed 1800K. Even if the temperature in the edge combustion zones can be controlled, the central combustion zone remains the primary source of pollutants, and the higher the turbine's operating speed, the higher the pollutant concentration. Therefore, this heavy-duty gas turbine still suffers from a technical defect resulting in high pollutant concentrations. Summary of the Invention

[0006] The purpose of this application is to provide a heavy-duty gas turbine and its method of use, in order to solve the problem of how to reduce the concentration of pollutants generated by the heavy-duty gas turbine under high operating conditions.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] Firstly, this application proposes a technical solution for a heavy-duty gas turbine. The heavy-duty gas turbine includes a combustion chamber comprising an outer casing, an inner casing, and nozzles. An air passage is formed between the outer casing and the inner casing. The nozzles include a diffusion combustion nozzle and multiple premixed combustion nozzles. Fuel injected from each premixed combustion nozzle burns in the inner casing to form an edge combustion zone, and fuel injected from the premixed combustion nozzles burns in the inner casing to form a central combustion zone. The combustion chamber also includes a first and a second diverter pipe disposed in the inner casing. The first and second diverter pipes sequentially divide the interior of the inner casing from the edge to the center to form a first airflow channel, a second airflow channel, and a third airflow channel. The first, second, and third airflow channels are used to sequentially divert air from the air passages to form a first portion of air, a second portion of air, and a third portion of air. The first portion of air participates in the premixed combustion in the edge combustion zone. The third portion of air participates in the diffusion combustion in the central combustion zone. The second portion of air cools the high-temperature flue gas formed by the diffusion combustion in the central combustion zone, reducing the temperature gradient between the edge combustion zone and the central combustion zone.

[0009] As a specific embodiment of this application, the flow area ratio of the first air channel, the second air channel, and the third air channel is 9.0 to 11.0: 0.9 to 1.1: 1.8 to 2.2.

[0010] As a specific embodiment of this application, a first swirler is provided between the first splitter pipe and the second splitter pipe; a second swirler is provided between the diffusion combustion nozzle and the second splitter pipe.

[0011] As a specific embodiment of this application, the premixed combustion nozzle includes: The first tube body is equipped with a third cyclone separator and multiple first nozzles at its end; A movable cover plate is disposed inside the first pipe body; the movable cover plate is provided with multiple adjustment holes; the minimum flow area of ​​the first pipe body is equal to the sum of the flow areas of each adjustment hole.

[0012] As a specific embodiment of this application, the diffusion combustion nozzle includes: The second tube body has a fourth cyclone separator installed inside; Multiple premixed branch pipes; each premixed branch pipe is disposed on the second pipe body and is connected to the second pipe body; each premixed branch pipe is distributed circumferentially around the second pipe body; each premixed branch pipe is provided with a second nozzle; each second nozzle is used to connect the interior of the second pipe body and the third air flow channel.

[0013] As a specific embodiment of this application, the centerline of each second nozzle is perpendicular to the centerline of the second split pipe; the inner diameter of each second nozzle on each premixed branch pipe increases along a first direction; the first direction is parallel to the centerline of the premixed branch pipe and points from the first end to the last end of the premixed branch pipe.

[0014] As a specific embodiment of this application, each premixed branch pipe is provided with two rows of second nozzles along the first direction, and the ratio of the inner diameters of the two rows of second nozzles along the first direction is 17 to 21: 25 to 31.

[0015] As a specific embodiment of this application, the premixed combustion nozzle further includes: A switching tube is sleeved on the outside of the second tube body; a switching cavity is formed between the switching tube and the second tube body; a plurality of third spray holes are provided at the end of the switching tube; A fluid pipe is disposed in the switching pipe and communicates with the switching chamber; the fluid pipe is connected to the fuel pipe of the compressor purge pipe and the premixed combustion nozzle through a three-way valve.

[0016] As a specific embodiment of this application, the distance between the fourth hydrocyclone and the end of the second tube body is greater than or equal to 5 mm and less than or equal to 15 mm.

[0017] As a specific embodiment of this application, the inner casing is provided with a Venturi tube, and the distance between the smallest inner diameter of the Venturi tube and the end of the first diverter tube is greater than or equal to 20 mm and less than or equal to 30 mm, so that the air velocity in the first air channel is greater than or equal to 50 m / s and less than or equal to 60 m / s.

[0018] As a specific embodiment of this application, the inner casing is provided with multiple rows of air passages along its axial direction, and the inner wall of the inner casing is provided with annular baffles corresponding to each row of air passages. The annular baffles are used to change the airflow direction of the air entering the inner casing through the corresponding air passages, so that the air can flow in contact with the inner wall surface of the inner casing and the inner wall surface of the venturi tube.

[0019] Secondly, this application proposes a technical solution for a method of using a heavy-duty gas turbine. The method is applied to the heavy-duty gas turbine as described in the first aspect; the operating conditions of the heavy-duty gas turbine include low operating condition, medium operating condition, and high operating condition; when the heavy-duty gas turbine is in the low operating condition, its output power is less than or equal to 0.30 times its rated power; when the heavy-duty gas turbine is in the medium operating condition, its output power is greater than 0.30 times its rated power and less than or equal to 0.80 times its rated power; when the heavy-duty gas turbine is in the high operating condition, its output power is greater than 0.80 times its rated power and less than or equal to 1.09 times its rated power; the method of use includes: When the heavy-duty gas turbine is in a low operating condition, the first fuel ratio is equal to 100%; the first fuel ratio is the proportion of the amount of fuel supplied to the edge combustion zone by each premixed combustion nozzle of the heavy-duty gas turbine to the total amount of fuel supplied to the combustion chamber. When the heavy-duty gas turbine is in medium operating condition, the first fuel ratio is greater than or equal to 60% and less than or equal to 65%; the second fuel ratio is greater than or equal to 35% and less than or equal to 40%; the second fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone by the diffusion combustion nozzle to the total amount of fuel supplied to the combustion chamber; and the sum of the first fuel ratio and the second fuel ratio is equal to 100%. When the heavy-duty gas turbine is under high operating conditions, the first fuel ratio is 83% and the second fuel ratio is 17%.

[0020] As a specific embodiment of this application, when the heavy-duty gas turbine switches from medium operating condition to high operating condition, the method includes: The first fuel ratio is gradually reduced until it reaches 0; and while reducing the first fuel ratio, the third fuel ratio is gradually increased, with the decrease in the first fuel ratio being the same as the increase in the third fuel ratio; the third fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone by the switching pipe of the heavy-duty gas turbine to the total amount of fuel supplied to the combustion chamber. After the first fuel ratio is reduced to 0 and the flame between the inner casing and the first splitter is extinguished, the state of the heavy-duty gas turbine is maintained for a preset time. After the heavy-duty gas turbine is maintained in a state for a preset time, the first fuel ratio is gradually increased while the second and third fuel ratios are decreased until the first fuel ratio increases to 83%, the second fuel ratio decreases to 17%, and the third fuel ratio decreases to 0.

[0021] As a specific solution in this application, the method further includes: When the output power of the heavy-duty gas turbine is less than or equal to 0.7 times the rated power, the opening of the compressor inlet guide vanes shall be maintained at 35%. When the output power of the heavy-duty gas turbine is greater than 0.7 times the rated power and less than or equal to 1.0 times the rated power, the opening degree of the compressor inlet guide vanes shall be adjusted according to the following calculation formula:

[0022] in, This indicates the opening degree of the compressor inlet guide vanes when the output power of the heavy-duty gas turbine is equal to t times the rated power; This indicates that the output power of the heavy-duty gas turbine is equal to t times its rated power; When the output power of the heavy-duty gas turbine is greater than 1.0 times the rated power, the opening of the compressor inlet guide vanes is maintained at 100%.

[0023] Compared with the prior art, the beneficial effects of this application are: This application precisely divides the air entering the inner casing into three streams through the design of a first, second, and third air flow channel. The first air flow channel provides sufficient air for lean premixed combustion in the edge combustion zone, effectively reducing the overall combustion temperature. The second air flow channel forms an intermediate air isolation layer, which not only avoids excessively high local temperature gradients caused by direct contact between the central and edge combustion zones, but also gradually dilutes the high-temperature flue gas in the center during the latter half of the combustion reaction. The third air flow channel supplies an appropriate amount of air to the central combustion zone, maintaining the stabilizing core function of the central diffused flame while preventing excessive fuel richness in the central region. This design strictly controls the overall maximum combustion temperature of the combustion chamber to around 1800K, suppressing the formation of nitrogen oxides at the reaction mechanism level, while not interfering with the flame front structure of the core combustion. This solves the contradiction in existing technologies where heavy-duty gas turbines struggle to balance excessive pollutant emissions and combustion stability under high operating conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a heavy-duty gas turbine combustion chamber in the prior art; Figure 2 This is a schematic diagram of the structure of a heavy-duty gas turbine combustion chamber proposed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a nozzle proposed in an embodiment of this application; Figure 4 This is a cross-sectional schematic diagram of a premixed combustion nozzle proposed in an embodiment of this application; Figure 5 This is a cross-sectional schematic diagram of a diffusion combustion nozzle proposed in an embodiment of this application; Figure 6 The heavy-duty gas turbine combustor proposed in this application embodiment is according to Figure 5 A partial cross-sectional view of the NN line; Figure 7 This is a cross-sectional schematic diagram of an inner casing proposed in an embodiment of this application; Figure 8 for Figure 7 Enlarged schematic diagram of section R in the middle; Figure 9 This is a graph showing the variation of pollutant emissions from a heavy-duty gas turbine under operating conditions, as proposed in an embodiment of this application. Figure 10 This is a cross-sectional diagram showing the fuel concentration distribution at the end of the third airflow channel in Comparative Example 1. Figure 11 This is a cross-sectional distribution diagram of fuel concentration at the end of the third airflow channel in Example 1.

[0025] In the diagram: 1. Outer casing; 11. Edge combustion zone; 12. Central combustion zone; 2. Inner casing; 21. First branch pipe; 22. Second branch pipe; 23. Second swirler; 24. First swirler; 25. Annular baffle; 26. Air passage; 3. Nozzle; 31. Premixed combustion nozzle; 311. First pipe body; 312. First nozzle; 313. Third swirler; 314. Movable cover plate; 315. Adjustment hole; 32. Diffusion combustion nozzle; 321. Second pipe body; 322. Premixed branch pipe; 323. Second nozzle; 324. Switching pipe; 325. Switching chamber; 326. Fluid pipe; 327. Third nozzle; 328. Fourth swirler; 4. Air passage; 5. Venturi tube; 61. Dividing line; 62. First region; 63. Second region. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] It should be noted that in the description of this application, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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. Therefore, they should not be construed as limitations on this application.

[0028] Furthermore, it should be understood that, for ease of description, the dimensions of the various components shown in the accompanying drawings are not drawn to actual scale; for example, the thickness or width of some layers may be exaggerated relative to other layers.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined or described in one figure, it will not need to be discussed or described in detail in the description of the subsequent figures.

[0030] It should be noted that in this application, components or structures used to guide fluid in a heavy-duty gas turbine (e.g., the first pipe body 311, premixed branch pipe 322, first air flow channel, and air passage 4, etc.) are defined as having a "head end" and a "tail end." The head end refers to the end where fluid (e.g., fuel, air, or a mixture) flows into the component or structure, while the tail end refers to the end where fluid flows out of the component or structure. In other words, in the heavy-duty gas turbine proposed in the embodiments of this application, the flow direction of the fluid during use is always from the head end to the tail end of a certain component or structure.

[0031] It should be noted that the core improvement direction of this application mainly focuses on the combustion chamber section of heavy-duty gas turbines, aiming to solve problems such as... Figure 1 The heavy-duty gas turbine with the combustion chamber structure shown still faces the technical challenge of reducing pollutant concentrations under high operating conditions. Therefore, the embodiments in this application only focus on the combustion chamber-related parts of the heavy-duty gas turbine, without detailing conventional components such as the compressor, turbine, exhaust system, and fuel supply system. The specific structure, assembly method, and basic working principle of these conventional components are mature technologies in the gas turbine field and can be directly referenced from existing technical solutions; therefore, they will not be elaborated upon in this application.

[0032] It should be noted that, having such Figure 1 The advantage of the heavy-duty gas turbine with the combustion chamber structure shown is that, when the heavy-duty gas turbine is under high operating conditions, most of the fuel enters the edge combustion zone 11 for lean premixed combustion, while a small portion of the fuel enters the central combustion zone 12 for diffusion combustion. The lean premixed combustion in the edge combustion zone 11 effectively suppresses the formation of pollutants such as nitrogen oxides by reducing the overall combustion temperature and eliminating localized high-temperature zones. The diffusion combustion in the central combustion zone 12 forms a stable flame core, continuously maintaining the overall combustion stability of the combustion chamber and preventing abnormal operating conditions such as flameout and backfire.

[0033] It should be noted that existing technologies have features such as Figure 1 Many heavy-duty gas turbines employ the combustion chamber structure shown, such as the R0110, SGT5-8000H, and M701F models. Figure 1The combustion chamber is shown. It should be noted that the above list is only a representative model using this type of combustion chamber structure and is not an exhaustive list of all related products. The combustion chamber structure forming the edge combustion zone 11 and the central combustion zone 12 is the mainstream structure of current heavy-duty gas turbine combustion chambers, widely used by major gas turbine R&D and manufacturing companies worldwide in various mature products of different power levels and application scenarios (e.g., combined cycle power generation, industrial drive, and marine power). Due to the differences in the specific structural dimensions, nozzle arrangement, airflow channel design, and fuel supply parameters of different manufacturers' combustion chambers, and the continuous iteration and updates of each manufacturer's gas turbine product series, resulting in a large number of improved and customized models, this application cannot comprehensively and exhaustively list all heavy-duty gas turbine models using this basic combustion chamber structure. Therefore, in order to clearly and completely explain the technical solution, working principle, and beneficial effects of this application, and to facilitate those skilled in the art to fully understand and implement this application, the specific embodiments in the subsequent specific embodiments of this application will use the R0110 heavy-duty gas turbine as an example to provide detailed descriptions of each specific embodiment. However, it should be clarified that the technical improvements proposed in this application are not limited to the R0110 heavy-duty gas turbine. For all heavy-duty gas turbines that adopt the basic combustion chamber structure of "the outer casing and inner casing forming an air passage, the nozzle including a central diffusion combustion nozzle and multiple circumferentially distributed edge premixed combustion nozzles, forming a central combustion zone and an edge combustion zone respectively", the technical solution of this application has the same applicability, can achieve the same technical effect and solve the same technical problem, and will not be explained or elaborated again below.

[0034] It should be noted that in this application, the heavy-duty gas turbine operating under condition x means that the output power of the heavy-duty gas turbine is equal to x times its rated power. For example, condition 0.7 means that the output power of the heavy-duty gas turbine is equal to 0.7 times its rated power; condition 1.0 means that the output power of the heavy-duty gas turbine is equal to 1.0 times its rated power, and so on. Further explanation will not be provided below.

[0035] In order to solve the problems mentioned in the background art, such as Figure 1This application addresses the technical problem of high pollutant concentrations in heavy-duty gas turbines with the combustion chamber structure shown in the previous application, and proposes an embodiment of such a gas turbine. Specifically, the heavy-duty gas turbine includes a combustion chamber comprising an outer casing 1, an inner casing 2, and nozzles 3. An air passage 4 is formed between the outer casing 1 and the inner casing 2. The nozzles 3 include a diffusion combustion nozzle 32 and multiple premixed combustion nozzles 31. Fuel ejected from each premixed combustion nozzle 31 burns in the inner casing 2 to form an edge combustion zone 11, and fuel ejected from the premixed combustion nozzles 31 burns in the inner casing 2 to form a central combustion zone 12. In this embodiment, the combustion chamber also includes a first branch pipe 21 and a second branch pipe 22 disposed in the inner casing 2. Figure 2 As shown, the first diversion pipe 21 and the second diversion pipe 22 divide the interior of the inner casing 2 from the edge to the center to form a first air flow channel, a second air flow channel and a third air flow channel.

[0036] During use, air from air channel 4 (i.e., as...) Figure 2 The air flowing along path A (as shown) can be divided into three parts, one of which (hereinafter referred to as the first part of the air) is as follows: Figure 2 As shown in path B, the air enters the first airflow channel (that is, the channel formed between the inner casing 2 and the first split pipe 21); another portion of air (hereinafter referred to as the second portion of air) as... Figure 2 As shown in path C, the air enters the second airflow channel (that is, the channel formed between the first split pipe 21 and the second split pipe 22); the last portion of air (hereinafter referred to as the third portion of air) is as follows: Figure 2 The path D in the diagram indicates that the air enters the third airflow channel (that is, the channel formed between the second split pipe 22 and the diffusion combustion nozzle 32).

[0037] Specifically, the first portion of air subsequently enters the edge combustion zone 11 to participate in premixed combustion; the third portion of air subsequently enters the central combustion zone 12 to participate in diffusion combustion. The second portion of air is located between the first and third portions, smoothly advancing downstream along the combustion chamber axis, without directly penetrating into the core combustion areas of the edge combustion zone 11 and the central combustion zone 12, thus avoiding interference with the flame front structure and combustion stability of the two combustion zones. The second portion of air is gradually released and participates in the combustion process mainly in the latter half of the combustion reaction (i.e., the high-temperature flue gas area downstream of the core flame front). In other words, the second portion of air first comes into full contact and mixes with the high-temperature flue gas generated by diffusion combustion in the central combustion zone 12, directly reducing the flue gas temperature downstream of the central combustion zone 12 through the dilution and heat exchange effect of the low-temperature air; at the same time, it can fill the transition area between the central combustion zone 12 and the edge combustion zone 11, eliminating the excessively high local temperature gradient caused by the large temperature difference at the boundary between the two zones, and strictly controlling the overall maximum combustion temperature of the combustion chamber to around 1800K. This design avoids problems such as flame instability and backfire caused by additional air intervention in the core combustion process, and specifically solves the problem of local overheating in the central combustion zone 12 under high operating conditions due to increased fuel injection and insufficient air mixing. It suppresses the large-scale generation of pollutants such as nitrogen oxides from the reaction mechanism level, and achieves a balance between low emissions and combustion stability under high operating conditions.

[0038] It is important to note that precise airflow distribution is crucial for balancing low pollutant emissions and combustion stability in heavy-duty gas turbines. To avoid uneven fuel-air mixing in the combustion chamber due to an improper air ratio in the first, second, and third air channels (especially for the R0110 heavy-duty gas turbine), which could lead to problems such as excessively high localized temperatures, excessive pollutant emissions, high flame tube wall temperatures, and a high risk of backfire, this application specifies that the flow area ratio of the first, second, and third air channels can be 9.0 to 11.0:0.9 to 1.1:1.8 to 2.2.

[0039] In one embodiment of this application, the flow area ratio of the first air channel, the second air channel, and the third air channel can be 9.0:0.9:1.8; or it can be 11.0:1.1:2.2.

[0040] In another embodiment of this application, the flow area ratio of the first air channel, the second air channel and the third air channel can be 10:1:2.

[0041] It is important to note that setting the flow area ratio of the first, second, and third air channels to 10:1:2 aims to ensure that the proportion of air supplied to each air channel is close to 10:1:2. This allocation ratio precisely matches the combustion air requirements of the edge combustion zone 11 and the central combustion zone 12 in this application. The first air channel, with the largest air volume, provides sufficient air for the lean premixed combustion in the edge combustion zone 11, effectively reducing the overall combustion temperature. The intermediate air isolation layer formed by the second air channel avoids excessively high local temperature gradients caused by direct contact between the central combustion zone 12 and the edge combustion zone 11, and gradually participates in mixing and diluting the high-temperature flue gas in the latter half of the combustion reaction. The third air channel supplies an appropriate amount of air to the central combustion zone 12, maintaining the stability of the central diffusion flame while preventing excessive fuel richness and localized overheating in the central combustion zone 12 due to insufficient air. This precise area ratio design, when applied to the R0110 heavy-duty gas turbine, successfully controlled the flame temperature in the combustion chamber of the R0110 heavy-duty gas turbine to around 1803K. This not only suppressed the formation of nitrogen oxides from the reaction mechanism, but also... Figure 9 It can be seen that the improved heavy-duty gas turbine emits only 8.3 ppm of nitrogen oxides under operating condition 1.0, which meets the environmental protection requirement of ≤25 ppm of nitrogen oxides. It also ensures combustion stability across the entire operating range, fundamentally solving the core contradiction between high pollutant emissions and insufficient combustion reliability under high operating conditions in the prototype combustion chamber.

[0042] It should be noted that, as mentioned above, the combustion in the edge combustion zone 11 is lean premixed combustion. In this combustion mode, the fuel mixture is thin, the flame propagation speed is slow, and the edge combustion zone 11 is far from the stable flame core of the central diffused flame. Therefore, the edge combustion zone 11 itself is difficult to form stable and self-sustaining combustion, especially in the downstream region of the edge combustion zone 11, where the flame front is extremely prone to breakage due to airflow disturbances, fuel concentration fluctuations, or sudden changes in local temperature gradients, leading to overall combustion instability in the combustion chamber. This is one of the core causes of frequent flame interruption and blow-out phenomena during operating condition switching in existing heavy-duty gas turbines. To further improve the combustion stability of the combustion chamber across the entire operating range and avoid abnormal operating conditions such as flame interruption, blow-out, or backfire during operating condition switching, in one embodiment of this application, such as... Figure 2As shown, a first swirler 24 can be installed between the first splitter 21 and the second splitter 22. Specifically, the first swirler 24 can apply a tangential force to the axial airflow in the second airflow channel, causing it to form a rotating airflow. This rotating airflow can actively agitate the contact interface between the downstream combustion gases of the central combustion zone 12 and the edge combustion zone 11, ensuring that the central diffused flame can continuously propagate the flame to the edge combustion zone, thereby forming a stable flame bridging structure between the central diffused flame and the edge lean premixed flame. This bridging structure not only fully utilizes the flame-stabilizing core role of the central diffused flame, but also effectively ensures the continuity and stability of the edge lean premixed combustion, fundamentally solving the technical problem of edge flame instability in the lean premixed combustion mode.

[0043] In this embodiment, there are no restrictions on the shape and structure of the nozzle 3, as long as it has a premixed combustion nozzle 31 and a diffusion combustion nozzle 32. For example, the nozzle 3 can be directly adopted from the nozzles of a heavy-duty gas turbine of model R0110, a heavy-duty gas turbine of model SGT5-8000H, or a heavy-duty gas turbine of model M701F.

[0044] In order to enhance the mixing uniformity of the fuel (hereinafter referred to as the first part of fuel) sprayed from the premixed combustion nozzle 31 with the first part of air, so as to reduce the risk of local fuel over-enrichment in the edge combustion zone 11, further suppress the generation of pollutants such as nitrogen oxides, and improve the combustion stability of the edge lean premixed flame, in one embodiment of this application, the premixed combustion nozzle 31 includes a first tube body 311, and the end of the first tube body 311 is provided with a third swirler 313 and a plurality of first nozzle holes 312.

[0045] When in use, the airflow path of the first part is as follows: Figure 4 As shown in path F, the first portion of air forms a high-speed rotating airflow through the third swirler 313. This swirling airflow generates strong shear turbulence and a central low-pressure recirculation zone, which not only prolongs the contact mixing time between fuel and air but also continuously ignites the downstream mixture through the recirculating high-temperature flue gas, providing auxiliary flame stabilization for the edge flame. The flow path of the first portion of fuel is as follows: Figure 4 As shown in path E, the first part of the fuel is injected into the swirling air field in the form of multiple atomized jets through the first nozzle 312. Under the action of turbulent shear force, it is rapidly broken up and atomized, and undergoes high-intensity momentum and mass exchange with the swirling air, completing the initial uniform mixing within a very short distance.

[0046] To address the problem of uneven fuel concentration distribution in the edge combustion zones 11 of different gas turbines due to machining tolerances and assembly deviations in actual manufacturing, which leads to abnormal local combustion temperatures and fluctuations in pollutant emissions, in one embodiment of this application, the premixed combustion nozzle 31 may further include a movable cover plate 314. For example... Figure 4 As shown, the movable cover plate 314 is disposed inside the first tube body 311, and the movable cover plate 314 is provided with multiple adjustment holes 315. During the manufacturing process, if it is necessary to adjust the fuel concentration of the edge combustion zone 11, it is only necessary to replace the movable cover plate 314 with different hole diameters for the adjustment holes 315, without the need for secondary processing or complete replacement of the premixed combustion nozzle 31, thereby improving the debugging efficiency and adaptability of the combustion chamber fuel distribution and significantly reducing the adjustment cost.

[0047] In this embodiment, the movable cover plate 314 can be connected to the first tube body 311 in any reasonable manner. For example, the movable cover plate 314 can form an interference fit with the first tube body 311 (that is, the outer diameter of the movable cover plate 314 is larger than the inner diameter of the first tube body 311); or, the movable cover plate 314 can form a threaded connection with the first tube body 311 (that is, the movable cover plate 314 is provided with an external thread, and the first tube body 311 is provided with an internal thread that matches the external thread).

[0048] In this embodiment, the diffusion combustion nozzle 32 can be a straight pipe. To improve the flame sustaining stability of the diffusion combustion in the central combustion zone 12, and to enhance the mixing uniformity of the central diffusion fuel and the air supplied by the third air channel, thus preventing localized excessive fuel richness and excessive combustion temperature in the central region due to the characteristic of simultaneous mixing and combustion of fuel and air, thereby suppressing the large-scale generation of pollutants such as nitrogen oxides in the central combustion zone 12 from the source, in one embodiment of this application, the diffusion combustion nozzle 32 includes a second pipe body 321. And as... Figure 5 As shown, a fourth cyclone separator 328 is provided inside the second tube body 321.

[0049] In use, the fourth cyclone separator 328 can circulate the fuel gas flow entering the second tube body 321 (i.e., as... Figure 5 The fuel flow path H is subjected to a continuous tangential force, which causes the fuel participating in diffusion combustion to form a stable high-speed swirling flow. After the swirling fuel is ejected from the end of the second tube body 321, it will generate strong shear turbulence and entrainment effect with the axial flow of the third air channel, which shortens the mixing time of fuel and air and improves the mixing uniformity. At the same time, a low-pressure high-temperature recirculation zone is formed in the core position of the central combustion zone 12. The recirculated high-temperature flue gas can continuously ignite the downstream fresh mixture, which not only solves the problem that the flame of the straight tube diffusion nozzle is easily blown out and has weak flame stabilization ability, but also effectively reduces the local peak temperature of the central combustion zone 12, further taking into account the combustion stability and low emission requirements under high operating conditions.

[0050] It should be noted that the end of the second tube body 321 is close to the central combustion zone 12, where the combustion temperature is relatively high. To prevent the fourth swirler 328 from being burned, the distance between the fourth swirler 328 and the end of the second tube body 321 can be limited (i.e., as shown in the figure). Figure 5 The distance S1 in the middle). In one embodiment of this application, the distance S1 is greater than or equal to 5 mm and less than or equal to 15 mm. If the distance S1 is less than 5 mm, the fourth cyclone separator 328 will be too close to the high-temperature flame front of the central combustion zone 12, and will be easily ablated, which will cause thermal deformation or even breakage of the cyclone separator blades, seriously affecting the operational reliability of the combustion chamber; if the distance S1 is greater than 15 mm, the swirling fuel generated by the fourth cyclone separator 328 may have its swirling intensity significantly reduced due to pipe wall friction and airflow diffusion before it reaches the end of the second tube body 321 and is ejected, making it difficult to form a sufficiently strong shear turbulence and entrainment effect with the third part of the air, which will lead to a decrease in the uniformity of fuel-air mixing and insufficient strength of the central low-pressure high-temperature recirculation zone. This may cause local fuel over-enrichment in the central combustion zone 12, leading to an increase in nitrogen oxide emissions, and may also weaken the self-sustaining flame stabilization capability of the central diffused flame, increasing the risk of flame blowout under low operating conditions.

[0051] To further reduce the concentration of nitrogen oxides generated in the central combustion zone 12 under high operating conditions, in one embodiment of this application, the diffusion combustion nozzle 32 may further include multiple premixed branch pipes 322. Each premixed branch pipe 322 is disposed on the second pipe body 321, and the premixed branch pipes 322 are distributed circumferentially around the second pipe body 321. Each premixed branch pipe 322 is provided with a second nozzle 323.

[0052] In this embodiment, the purpose of providing the second nozzle 323 is to connect the interior of the second pipe body 321 and the third air flow channel through each second nozzle 323.

[0053] During use, the fuel (referred to as the second part fuel) injected by multiple premixed branch pipes 322 is as follows: Figure 5As shown in path G, before entering the core flame region of the central combustion zone 12, it can undergo sufficient turbulent mixing with the axially flowing air (i.e., the third part of the air) in the third air channel to form a lean mixture with uniform fuel concentration (the fuel concentration in this mixture is higher than that in the mixture in the edge combustion zone 11). Subsequently, this mixture enters the central combustion zone 12 and forms premixed combustion, which together with the diffusion combustion flame ejected from the end of the second tube body 321 constitutes the central composite combustion zone. This design transforms part of the pure diffusion combustion in the central combustion zone 12 into low-NOx premixed combustion, which can reduce the local fuel-rich area caused by the mixing and combustion characteristics, further compress the reaction range for the generation of high-temperature NOx, while retaining the role of the central diffusion flame as a flame stabilizing core, and will not have a significant negative impact on the combustion stability of the combustion chamber under all operating conditions.

[0054] To further improve the uniformity of mixing between the second portion of fuel and the third portion of air, in one embodiment of this application, such as Figure 2 As shown, a second swirler 23 is also provided between the diffusion combustion nozzle 32 and the second splitter pipe 22.

[0055] Specifically, the second swirler 23 can apply a continuous tangential force to the mixture formed by the third portion of air and the second portion of fuel flowing axially in the third air channel, thereby creating a rotating flow field with stable swirling intensity. This rotating flow field can break the laminar state between the second portion of fuel and the third portion of air, prolong the contact mixing time between the fuel and air, and allow the second portion of fuel and the third portion of air to form a lean mixture with higher homogeneity before entering the core flame region of the central combustion zone 12. This further eliminates the local over-rich fuel region in the central combustion zone 12, compressing the high-temperature nitrogen oxide generation range from the reaction source.

[0056] To further improve the mixing uniformity of the second portion of fuel and the third portion of air, in one embodiment of this application, the axis of each second nozzle 323 is perpendicular to the axis of the second splitter pipe 22. It should be noted that if the axis of the second nozzle 323 is perpendicular to the axis of the second splitter pipe 22, the direction of the fuel ejected from the second nozzle 323 is necessarily perpendicular to the flow direction of the third portion of air. That is, if the second portion of fuel is injected at a 90° orthogonal angle into the third portion of air flowing axially along the second splitter pipe 22, the fuel jet and the axial airflow will generate the maximum turbulent shear force, which can directly penetrate the laminar boundary layer of the airflow, forming a large-scale turbulent mixing zone downstream of the jet, significantly enhancing the momentum exchange and mass diffusion process between the second portion of fuel and the third portion of air. In other words, compared to oblique injection or axial injection, vertical injection can avoid the problems of prolonged mixing distance and insufficient mixing intensity caused by the fuel jet having a velocity component in the same direction as the air flow. At the same time, it can prevent fuel from concentrating in one side of the third air flow channel and ensure that the fuel is evenly distributed across the entire circumferential cross section of the third air flow channel.

[0057] To further improve the uniformity of mixing between the second portion of fuel and the third portion of air, in one embodiment of this application, such as Figure 5 As shown, the inner diameters of the second nozzles 323 arranged along a first direction on each premixed branch pipe 322 increase progressively. The first direction is parallel to the axis of the premixed branch pipe 322 and points from the beginning to the end of the premixed branch pipe 322. It should be noted that... Figure 6 The heavy-duty gas turbine combustor proposed in this application embodiment is according to Figure 5 A partial cross-sectional view of the NN line. (See diagram.) Figure 6As shown, a third airflow channel is formed between the diffusion combustion nozzle 32 and the second splitter pipe 22. The third airflow channel is divided into a first region 62 (near the second splitter pipe 22) and a second region 63 (near the diffusion combustion nozzle 32) by a dividing line 61. The widths of the first region 62 and the second region 63 along the radial direction of the diffusion combustion nozzle 32 (i.e., the radial direction of the third airflow channel) are equal. Clearly, the cross-sectional area of ​​the first region 62 is larger than that of the second region 63. Since the air volume in a certain region is proportional to its cross-sectional area within the same flow channel, the air volume in the first region 62 will always be greater than that in the second region 63 during gas turbine operation. If the inner diameters of all the second nozzles 323 are the same, then, neglecting fuel friction resistance, the fuel volume in the first region 62 and the second region 63 will be essentially the same. In other words, if the inner diameters of all the second nozzles 323 are the same, it will inevitably cause uneven fuel concentration in the radial direction of the third airflow channel. It should be noted that in this application, the frictional resistance of the fuel is relatively large and cannot be ignored. When the fuel flows along the first direction inside the premixed branch pipe 322, the static pressure will continuously decrease due to frictional resistance losses. If all the second nozzles 323 adopt a uniform inner diameter design, the injection pressure difference of the second nozzles 323 at different positions will gradually decrease along the first direction, resulting in a significant decrease in fuel injection flow rate along the flow path. This leads to a higher fuel concentration in the area closer to the diffusion combustion nozzle 32 in the third air channel and a lower fuel concentration in the area closer to the second split pipe 22, ultimately forming a significant fuel concentration gradient along the radial direction of the third air channel.

[0058] This embodiment, by progressively increasing the inner diameter of each second nozzle 323 along the first direction, can precisely match the static pressure decay pattern within the premixed branch pipe. A smaller inner diameter nozzle is used at the beginning of the premixed branch pipe (i.e., the region with higher static pressure) to limit excessive fuel injection; a larger inner diameter nozzle is used at the end of the premixed branch pipe (i.e., the region with lower static pressure) to compensate for the flow rate decrease caused by static pressure loss. This design allows the fuel in the third airflow channel to be evenly distributed radially, reducing localized rich and lean fuel zones caused by mismatches in the amount of fuel injected from each second nozzle 323 on each premixed branch pipe 322.

[0059] In one specific embodiment of this application, each premixed branch pipe 322 is provided with two rows of second nozzles 323 along the first direction, and the ratio of the inner diameters of the two rows of second nozzles 323 along the first direction can be 17 to 21:25 to 31. That is, the ratio of the inner diameters of the two rows of second nozzles 323 along the first direction is greater than or equal to 17:31 and less than or equal to 21:25.

[0060] To verify the effectiveness of setting the inner diameter of each second nozzle 323 to increase along the first direction, Example 1 and Comparative Example 1 are presented below.

[0061] Example 1 In this embodiment, four premixed branch pipes 322 are arranged circumferentially along the second pipe body 321. Each premixed branch pipe 322 is provided with two rows of second nozzles 323 along the first direction. The inner diameter ratio of these two rows of second nozzles 323 along the first direction is 19:28, and the axis of each second nozzle 323 is perpendicular to the axis of the second branch pipe 22.

[0062] Comparative Example 1 In this comparative example, except that the inner diameter ratio of the two rows of second nozzles 323 along the first direction is 1:1, all other parameters are the same as in Example 1. This concludes the introduction of Comparative Example 1.

[0063] Specifically, Figure 10 This is a diagram showing the fuel concentration distribution at the end section of the third airflow channel in Comparative Example 1. Figure 11 This is a fuel concentration distribution diagram at the end section of the third airflow channel in Example 1. Clearly, compared to Comparative Example 1, the mixing uniformity of the second portion of fuel and the third portion of air in Example 1 is better. For example, Figure 10 The fuel concentration at the center of the swirl is close to 0.15, while the fuel concentration at the edge of the swirl is close to 0.0675. Figure 11 The fuel concentration at both the center and edge of the swirl is close to 0.0600.

[0064] Specifically, Figure 10 and Figure 11 The fuel concentration in the figure is expressed as a molar percentage. Figure 10 and Figure 11 Scientific notation is used in all of them, for example: Figure 10 In this context, 1.50e-01 equals 0.15; Figure 11 The 6.75e-02 in the equation equals 0.0675, which will not be elaborated on here.

[0065] To further reduce the generation of pollutants during combustion and improve combustion stability, in one embodiment of this application, a Venturi tube 5 may be provided inside the inner casing 2. It is important to understand that the Venturi tube 5 can generate the Venturi effect through its gradually narrowing and widening flow channel structure, creating a local negative pressure through airflow acceleration. This induces a stable high-temperature flue gas recirculation zone along the axial direction of the Venturi tube 5 downstream of its throat (i.e., the point of minimum inner diameter). This recirculation zone can continuously entrain the high-temperature flue gas from the combustion zone to the mixed gas outlet of the edge combustion zone 11, providing continuous and stable ignition energy for the lean premixed mixture, improving the flame stabilization performance of the edge lean premixed flame, and reducing the probability of flame interruption or blow-out during operating condition switching. Simultaneously, the forced acceleration process of the airflow in the narrowing section of the Venturi tube 5 can effectively increase the axial velocity of the mixed gas in the first airflow channel, thereby blocking the flame from propagating backwards into the premixed combustion nozzle 31. Furthermore, after the mixed gas enters the expansion section of the Venturi tube 5, as the cross-sectional area of ​​the flow channel gradually expands along the axial direction, the axial velocity of the mixed gas gradually decreases, the static pressure continues to rise, and the radial diffusion capacity of the mixed gas is greatly enhanced, which can drive the unevenly mixed air and fuel in the mixed gas to undergo sufficient secondary turbulent mixing in the radial and circumferential directions of the flow channel.

[0066] It is important to understand that in conventional designs, in order to avoid the throat of the Venturi tube 5 (i.e., the part with the smallest inner diameter) being burned, the throat of the Venturi tube 5 should be as close as possible to the end of the diffusion combustion nozzle 32, which means that the throat of the Venturi tube 5 should be as far away as possible from the combustion zone (i.e., the edge combustion zone 11 and the center combustion zone 12).

[0067] In order to ensure that the throat of the venturi tube 5 is sufficiently close to the end of the diffusion combustion nozzle 32, in one embodiment of this application, the distance between the minimum inner diameter of the venturi tube 5 and the end of the first diverter 21 (i.e., as shown in the figure) is... Figure 7The distance S2 shown can be 5mm. It should be noted that if the distance S2 is 5mm, the velocity of the mixed gas at the end of the first air channel is approximately 70.42m / s. After extensive verification by the inventors, it was found that if the velocity of the mixed gas at the end of the first air channel exceeds 60m / s, at least two technical problems are likely to occur: First, the mixed gas flowing out of the first air channel participates in lean premixed combustion in the edge combustion zone 11. If the velocity of the mixed gas is too high, the flame in the edge combustion zone 11 is easily extinguished. Second, as mentioned above, the ratio of air supplied to the first, second, and third air channels should be approximately 10:1:2 to ensure that less pollutant is produced during combustion. Excessive velocity will cause a sudden drop in static pressure inside the first air channel, disrupting the flow distribution balance of the three channels. The air intake of the first air channel will increase abnormally, crowding out the air share of the second and third air channels, causing the actual ratio to deviate from the optimal value. Insufficient air in the second airflow channel prevents the formation of an effective intermediate isolation layer, resulting in a severe temperature gradient at the boundary between the two zones. Reduced air volume in the third airflow channel leads to uneven fuel mixing in the central combustion zone, resulting in large areas of over-rich fuel and an exponential increase in nitrogen oxide production. Therefore, in one embodiment of this application, the distance between the smallest inner diameter of the venturi tube 5 and the end of the first branch pipe 21 can be greater than or equal to 20 mm and less than or equal to 30 mm, so that the airflow velocity in the first airflow channel is greater than or equal to 50 m / s and less than or equal to 60 m / s.

[0068] Specifically, in the embodiments of this application, the distance between the smallest inner diameter of the Venturi tube 5 and the end of the first shunt tube 21 can be any one of 20.0mm, 21.0mm, 22.0mm, 23.0mm, 24.0mm, 25.0mm, 25.5mm, 26.0mm, 27.0mm, 28.0mm, 29.0mm and 30.0mm, or any distance between two adjacent distances mentioned above.

[0069] As mentioned above, if the distance between the throat of the venturi tube 5 and the end of the first shunt tube 21 (i.e., as...) Figure 7 The larger the distance S2 shown, the easier it is for the throat of the venturi tube 5 to be burned. To avoid burning of the throat of the venturi tube 5, in one embodiment of this application, the inner casing 2 is provided with multiple rows of air passages 26 along its axial direction. Figure 8 As shown, the inner wall of the inner casing 2 is provided with annular baffles 25 corresponding to each row of air passages 26. The annular baffles 25 are used to change the airflow direction of the air entering the inner casing 2 through the corresponding air passages 26, so that the air can flow in contact with the inner wall surface of the inner casing 2 and the inner wall surface of the venturi tube 5.

[0070] In use, cooling air from the air passage 4 between the outer casing 1 and the inner casing 2 is injected radially into the inner casing 2 through multiple rows of axially arranged air holes 26. When the high-speed injected cooling air impacts the frontal surface of the corresponding annular baffle 25, its radial flow direction is forcibly deflected, turning into axial wall-following flow along the inner wall of the inner casing 2 and the outer wall of the venturi tube 5 (i.e., as shown in the image). Figure 8 As shown in the middle path L), a continuous and uniform cryogenic gas protective layer is eventually formed on the surface of both walls to prevent the throat of the Venturi tube 5 from being ablated.

[0071] As will be discussed below, the differences between the first fuel ratio (the proportion of fuel supplied to the edge combustion zone 11 by the various premixed combustion nozzles 31 to the total fuel supplied to the combustion chamber) and the second fuel ratio (the proportion of fuel supplied to the central combustion zone 12 by the diffusion combustion nozzles 32 to the total fuel supplied to the combustion chamber) are significant when the heavy-duty gas turbine is operating at medium and high conditions. If the first and second fuel ratios are directly adjusted when the heavy-duty gas turbine switches from medium to high operating conditions, it will cause drastic and unsteady abrupt changes in the fuel concentration field, flow field, and temperature field inside the combustion chamber. That is, the fuel supply to the edge combustion zone 11 will increase significantly in a short period of time, while the fuel supply to the central combustion zone 12 will decrease sharply. This will completely disrupt the original balance of flame energy transfer and thermal radiation between the two combustion zones. The role of the central diffuse flame as a flame stabilizing core will be drastically weakened, and the edge lean premixed flame will lose a continuous and stable ignition energy source, easily leading to severe operational accidents such as flame front breakage, local blowout, or even complete combustion chamber flameout. Based on this, in one embodiment of this application, such as Figure 5 As shown, the premixed combustion nozzle 31 may further include a switching pipe 324 and a fluid pipe 326. The switching pipe 324 is sleeved outside the second pipe body 321, and a switching cavity 325 is formed between the switching pipe 324 and the second pipe body 321. Multiple third nozzles 327 are provided at the end of the switching pipe 324. The fluid pipe 326 is disposed within the switching pipe 324 and communicates with the switching cavity 325. The fluid pipe 326 is connected to the compressor purge pipe and the fuel pipe of the premixed combustion nozzle 31 via a three-way valve.

[0072] In this embodiment, the third nozzle 327 is used to connect the central combustion zone 12 of the combustion chamber and the interior of the switching pipe 324, so that when the gas turbine switches from medium operating condition to high operating condition, the fuel in the switching pipe 324 can be smoothly injected into the central combustion zone 12 to participate in combustion.

[0073] When switching a heavy-duty gas turbine from medium to high operating conditions, the three-way valve can be adjusted first to connect the fluid pipe 326 to the fuel pipe of the premixed combustion nozzle 31. This transfers the fuel input from the premixed combustion nozzle 31 to the combustion chamber via the switching pipe 324, gradually reducing the first fuel ratio of the premixed combustion nozzle 31 until it reaches 0. Finally, the first and second fuel ratios are gradually adjusted to the target values ​​(for detailed steps, refer to the embodiment of the heavy-duty gas turbine usage method below). In other words, this embodiment, through the setting of the switching pipe 324 and the fluid pipe 326, achieves a smooth transition of fuel supply from medium to high operating conditions in the heavy-duty gas turbine. This avoids drastic changes in the combustion chamber flow field and temperature field caused by directly adjusting the fuel ratio between the edge and center combustion zones, eliminating the malignant operational risks of a sudden reduction in the central flame stabilizing core's role and the loss of continuous ignition energy in the lean premixed flame at the edges, leading to flame front breakage, partial blow-out, or even overall flameout.

[0074] After the heavy-duty gas turbine switches to high operating conditions, the three-way valve can be adjusted to connect the fluid pipe 326 to the compressor purging pipe. If the fluid pipe 326 is connected to the compressor purging pipe, the purging gas from the compressor can continuously purge and cool the end of the switching pipe 324, preventing it from being burned. In other words, in this embodiment, it can effectively prevent the switching pipe 324 from being eroded and deformed due to prolonged exposure to high-temperature flue gas, thus extending its service life.

[0075] The embodiment of the heavy-duty gas turbine proposed in this application precisely divides the air entering the inner casing into three streams through the arrangement of a first air channel, a second air channel, and a third air channel. The first air channel provides sufficient air for lean premixed combustion in the edge combustion zone, effectively reducing the overall combustion temperature. The second air channel forms an intermediate air isolation layer, which not only avoids excessively high local temperature gradients caused by direct contact between the central combustion zone and the edge combustion zone, but also gradually dilutes the high-temperature flue gas in the center during the latter half of the combustion reaction. The third air channel supplies an appropriate amount of air to the central combustion zone, maintaining the core role of the central diffuse flame while preventing excessive fuel richness in the central region. This design strictly controls the overall maximum combustion temperature of the combustion chamber to around 1800K, suppressing the formation of nitrogen oxides at the reaction mechanism level, while not interfering with the flame front structure of the core combustion. This solves the core contradiction in existing heavy-duty gas turbines where excessive pollutant emissions and combustion stability are difficult to balance under high operating conditions.

[0076] Having introduced the heavy-duty gas turbine proposed in the embodiments of this application, the following describes an embodiment of the method for using the heavy-duty gas turbine proposed in this application. Specifically, the method for using the heavy-duty gas turbine is applied to the heavy-duty gas turbine proposed in any of the above embodiments. In this embodiment, the operating conditions of the heavy-duty gas turbine include low operating condition, medium operating condition, and high operating condition. When the heavy-duty gas turbine is in low operating condition, the output power of the heavy-duty gas turbine is less than or equal to 0.30 times the rated power. When the heavy-duty gas turbine is in medium operating condition, the output power of the heavy-duty gas turbine is greater than 0.30 times the rated power and less than or equal to 0.80 times the rated power. When the heavy-duty gas turbine is in high operating condition, the output power of the heavy-duty gas turbine is greater than 0.80 times the rated power and less than or equal to 1.09 times the rated power.

[0077] To ensure that heavy-duty gas turbines exhibit low pollutant emissions and high combustion stability across the entire operating range, in one embodiment of this application, the method of using a heavy-duty gas turbine includes: When the heavy-duty gas turbine is in a low operating condition, the first fuel ratio is equal to 100%; the first fuel ratio is the proportion of the amount of fuel supplied to the edge combustion zone 11 by each premixed combustion nozzle 31 of the heavy-duty gas turbine to the total amount of fuel supplied to the combustion chamber. When the heavy-duty gas turbine is operating under medium conditions, the first fuel ratio is greater than or equal to 60% and less than or equal to 65%; the second fuel ratio is greater than or equal to 35% and less than or equal to 40%; the second fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone 12 by the diffusion combustion nozzle 32 to the total amount of fuel supplied to the combustion chamber; and the sum of the first fuel ratio and the second fuel ratio is equal to 100%. When a heavy-duty gas turbine is operating under high conditions, the primary fuel ratio is 83% and the secondary fuel ratio is 17%.

[0078] It is important to understand that this embodiment of the heavy-duty gas turbine operation method achieves a balance between combustion stability and low emissions across all operating conditions through a reasonable fuel ratio distribution scheme. When the heavy-duty gas turbine is operating at low temperatures, fully premixed combustion ensures ignition reliability and low-load flame stabilization capability. At medium operating temperatures, the edge combustion zone and the central combustion zone work together to supply energy, preserving the core flame stabilization function of the central diffused flame while initially reducing pollutant formation through premixed combustion. At high operating temperatures, most of the fuel is supplied to the edge combustion zone, and a small portion to the central combustion zone, precisely controlling the flame temperature at approximately 1803K, significantly reducing pollutant emissions.

[0079] In order to enable a heavy-duty gas turbine to stably switch from medium operating conditions to high operating conditions, in one embodiment of this application, the method for switching a heavy-duty gas turbine from medium operating conditions to high operating conditions includes steps 100 to 300.

[0080] Step 100: Gradually reduce the proportion of the first fuel until it reaches 0; and while reducing the proportion of the first fuel, gradually increase the proportion of the third fuel, with the decrease in the proportion of the first fuel being the same as the increase in the proportion of the third fuel.

[0081] In this embodiment, the third fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone 12 by the heavy-duty gas turbine through the switching pipe 324 to the total amount of fuel supplied to the combustion chamber.

[0082] In this embodiment, the same decrease in the first fuel ratio as the same increase in the third fuel ratio means that during the entire transition phase from medium to high operating conditions of the heavy-duty gas turbine, at any moment when the first fuel ratio decreases, the percentage decrease in the first fuel ratio relative to the initial switching point is numerically equal to the percentage increase in the third fuel ratio relative to the initial switching point (initial value of 0). Furthermore, the second fuel ratio remains unchanged at the set value under the pre-switching medium operating conditions, ensuring that the total fuel ratio supplied to the combustion chamber is always maintained at 100%. The core objective of this design is to ensure that the total fuel supply to the gas turbine remains constant during the transition from medium to high operating conditions, thereby maintaining stable output power and avoiding problems such as drastic changes in combustion chamber heat load and abnormal turbine speed caused by fluctuations in total fuel quantity. Simultaneously, it can smoothly transfer fuel supply to the edge combustion zone without altering the core energy of the central diffused flame stabilization, preventing abrupt changes in the internal flow field and temperature field of the combustion chamber, fundamentally eliminating the operational risks of flame front breakage, partial blow-out, and even overall flameout.

[0083] Step 200: The first fuel ratio is reduced to 0, and after the flame between the inner casing 2 and the first splitter pipe 21 is extinguished, the state of the heavy-duty gas turbine is maintained for a preset time.

[0084] In this embodiment, maintaining the state of the heavy-duty gas turbine for a preset time aims to ensure that the residual flame between the inner casing and the first splitter pipe is completely extinguished, preventing backfire, deflagration, and other serious safety accidents caused by the residual flame when fuel is subsequently supplied to the premixed combustion nozzle. At the same time, it allows the flow field, temperature field, and fuel concentration field inside the combustion chamber to fully relax and stabilize, eliminating local turbulence disturbances and sudden temperature gradient changes generated during fuel switching. In addition, it allows the diffused flame in the central combustion zone to fully fuse with the premixed flame supplied by the switching pipe, forming a stable composite combustion core, laying a solid foundation for subsequent smooth adjustment of the fuel ratio, and preventing problems such as combustion instability, flame blowout, or instantaneous exceedance of nitrogen oxide emissions.

[0085] In this embodiment, the preset time can be set according to requirements, for example, the preset time can be 3 seconds, 4 seconds or 5 seconds, etc.

[0086] Step 300: After the heavy-duty gas turbine is maintained in its current state for a preset time, the first fuel ratio is gradually increased while the second and third fuel ratios are decreased until the first fuel ratio increases to 83%, the second fuel ratio decreases to 17%, and the third fuel ratio decreases to 0.

[0087] This embodiment, through steps 100 to 300, achieves a smooth, shock-free transition of fuel supply from medium to high operating conditions in a heavy-duty gas turbine. The total fuel supply remains constant throughout the process, maintaining stable output power and avoiding drastic fluctuations in combustion chamber heat load and abnormal turbine speed. By transferring fuel supply to the edge combustion zone in stages and extinguishing residual flames before re-establishing combustion, the risks of flame front breakage, partial blow-out, and backfire caused by directly adjusting the fuel ratio are completely eliminated. Simultaneously, relaxation time for the flow and temperature fields is reserved to allow for sufficient stabilization of the combustion chamber, ensuring continuous and reliable combustion during the transition, while keeping instantaneous nitrogen oxide emissions within environmental standards. This balances the safety of operating condition switching, operational stability, and low emission requirements.

[0088] As mentioned earlier, the operating conditions of a gas turbine are positively correlated with the amount of fuel supplied to the combustion chamber. To maintain the optimal air-fuel ratio range within the combustion chamber, ensure the coordinated stability of lean premixed combustion and diffusion combustion, and strictly control the combustion temperature to suppress the formation of pollutants such as nitrogen oxides, the airflow entering the combustion chamber must be precisely adjusted synchronously according to changes in the fuel supply. The compressor inlet guide vanes, as the core control component for regulating the compressor's intake and output air pressure, directly determine the total amount of air delivered by the compressor to the combustion chamber air passage 4, thus affecting the flow distribution ratio of the first, second, and third air passages and the overall flow field characteristics within the combustion chamber.

[0089] The three-stream air-splitting combustor structure proposed in this application has significantly higher requirements for airflow matching accuracy than traditional combustors. If the compressor inlet guide vane opening is too large, it may lead to excessive air in the combustor and an excessively high air-fuel ratio, easily causing edge lean premixed flame blowout and combustion instability. If the compressor inlet guide vane opening is too small, it will result in insufficient air supply and an excessively low air-fuel ratio, causing local fuel richness in the combustor, a sharp rise in combustion temperature, and an exponential increase in nitrogen oxide generation. It will also disrupt the flow distribution balance of the three airflow channels, leading to the failure of the intermediate isolation layer in the second airflow channel and insufficient cooling of the central combustion zone 12. Based on this, in one embodiment of this application, the method may further include: When the output power of the heavy-duty gas turbine is less than or equal to 0.7 times the rated power, the opening of the compressor inlet guide vanes shall be maintained at 35%. When the output power of the heavy-duty gas turbine is greater than 0.7 times the rated power and less than or equal to 1.0 times the rated power, the opening degree of the compressor inlet guide vanes can be adjusted according to the following calculation formula:

[0090] in, This indicates the opening degree of the compressor inlet guide vanes when the output power of the heavy-duty gas turbine is equal to t times the rated power; This indicates that the output power of the heavy-duty gas turbine is equal to t times its rated power; When the output power of the heavy-duty gas turbine is greater than 1.0 times the rated power, the opening of the compressor inlet guide vanes is maintained at 100%.

[0091] This embodiment employs a three-stage compressor inlet guide vane opening precision control strategy to adapt to the airflow requirements of a three-stream air-splitting combustor. Under heavy-duty gas turbine operating conditions less than or equal to 0.7, the compressor inlet guide vanes are fixed at 35% opening to ensure the basic air supply to the combustor and prevent excessively high air-fuel ratios that could lead to the premixed flame being blown out. Under heavy-duty gas turbine operating conditions greater than 0.7 but less than or equal to 1.0, a linear calculation formula is used to dynamically adjust the opening, precisely matching changes in fuel supply and maintaining the optimal air-fuel ratio range to ensure balanced flow distribution across the three air streams. Under heavy-duty gas turbine operating conditions greater than 1.0, the compressor inlet guide vanes are fully open to 100% to meet the maximum intake requirements under overload conditions. This strategy maintains combustion temperature within the low-NOx range throughout the entire process, while also ensuring combustion stability and power output stability across all operating conditions.

[0092] The proposed method for using a heavy-duty gas turbine in this application divides the gas turbine operation into three operating ranges: low, medium, and high. A differentiated fuel ratio distribution strategy is then developed to achieve a balance between combustion stability and low emissions across the entire operating range. Under low operating conditions, a 100% premixed combustion mode is employed, fully utilizing the low-emission characteristics of lean premixed combustion while ensuring ignition reliability and low-load flame stabilization. Under medium operating conditions, 60% to 65% edge premixed combustion is combined with 35% to 40% center diffusion combustion, preserving the core flame stabilization function of the center diffusion flame while reducing pollutant generation through premixed combustion. Under high operating conditions, 83% of the fuel is supplied to the low-NOx lean premixed combustion zone, with only 17% of diffusion combustion maintained to ensure flame stability. This precisely controls the highest combustion temperature in the combustion chamber at approximately 1800K, suppressing the excessive generation of nitrogen oxides at the reaction mechanism level. This solves the core problem of excessive fuel richness and excessive pollutant emissions in the center combustion zone under high operating conditions in traditional heavy-duty gas turbines.

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

Claims

1. A heavy-duty gas turbine, comprising a combustion chamber, the combustion chamber including an outer casing (1), an inner casing (2), and a nozzle (3); an air passage (4) is formed between the outer casing (1) and the inner casing (2), the nozzle (3) including a diffusion combustion nozzle (32) and a plurality of premixed combustion nozzles (31), wherein fuel ejected from each premixed combustion nozzle (31) is burned in the inner casing (2) to form an edge combustion zone (11), and fuel ejected from the premixed combustion nozzles (31) is burned in the inner casing (2) to form a central combustion zone (12), characterized in that, The combustion chamber further includes a first diversion pipe (21) and a second diversion pipe (22) disposed in the inner casing (2). The first diversion pipe (21) and the second diversion pipe (22) divide the interior of the inner casing (2) from the edge to the center to form a first air flow channel, a second air flow channel and a third air flow channel. The first air flow channel, the second air flow channel and the third air flow channel are used to divert the air from the air channel (4) to form a first part of air, a second part of air and a third part of air. The first part of air is used to participate in the premixed combustion of the edge combustion zone (11). The third part of air is used to participate in the diffusion combustion of the central combustion zone (12). The second part of air is used to cool the high-temperature flue gas formed by the diffusion combustion of the central combustion zone (12) and reduce the temperature gradient between the edge combustion zone (11) and the central combustion zone (12).

2. The heavy-duty gas turbine according to claim 1, characterized in that, The flow area ratio of the first air channel, the second air channel and the third air channel is 9.0 to 11.0: 0.9 to 1.1: 1.8 to 2.

2.

3. The heavy-duty gas turbine according to claim 1, characterized in that, A first swirler (24) is provided between the first diverter pipe (21) and the second diverter pipe (22); a second swirler (23) is provided between the diffusion combustion nozzle (32) and the second diverter pipe (22).

4. The heavy-duty gas turbine according to claim 1, characterized in that, The premixed combustion nozzle (31) includes: The first tube body (311) is provided with a third cyclone separator (313) and multiple first nozzles (312) at its end. A movable cover plate (314) is disposed inside the first pipe body (311); the movable cover plate (314) is provided with a plurality of adjustment holes (315); the minimum runoff area of ​​the first pipe body (311) is equal to the sum of the runoff areas of each adjustment hole (315).

5. The heavy-duty gas turbine according to any one of claims 1 to 4, characterized in that, The diffusion combustion nozzle (32) includes: The second tube body (321) has a fourth cyclone separator (328) inside. Multiple premixed branch pipes (322); each premixed branch pipe (322) is disposed on the second pipe body (321), and each premixed branch pipe (322) is connected to the second pipe body (321); each premixed branch pipe (322) is distributed around the second pipe body (321) circumferentially; each premixed branch pipe (322) is provided with a second nozzle (323); each second nozzle (323) is used to connect the interior of the second pipe body (321) and the third air flow channel.

6. The heavy-duty gas turbine according to claim 5, characterized in that, The axis of each second nozzle (323) is perpendicular to the axis of the second split pipe (22); the inner diameter of each second nozzle (323) on each premixed branch pipe (322) increases along a first direction; the first direction is parallel to the axis of the premixed branch pipe (322) and points from the beginning end to the end end of the premixed branch pipe (322).

7. The heavy-duty gas turbine according to claim 6, characterized in that, Each premixed branch pipe (322) is provided with two rows of second nozzles (323) along the first direction, and the ratio of the inner diameters of the two rows of second nozzles (323) along the first direction is 17 to 21: 25 to 31.

8. The heavy-duty gas turbine according to claim 5, characterized in that, The premixed combustion nozzle (31) also includes: A switching tube (324) is sleeved on the outside of the second tube body (321); a switching cavity (325) is formed between the switching tube (324) and the second tube body (321); a plurality of third spray holes (327) are provided at the end of the switching tube (324). A fluid pipe (326) is disposed on the switching pipe (324) and communicates with the switching chamber (325); the fluid pipe (326) is connected to the fuel pipe of the compressor cleaning pipe and the premixed combustion nozzle (31) through a three-way valve.

9. The heavy-duty gas turbine according to claim 5, characterized in that, The distance between the fourth hydrocyclone (328) and the end of the second tube body (321) is greater than or equal to 5 mm and less than or equal to 15 mm.

10. The heavy-duty gas turbine according to any one of claims 1 to 4, characterized in that, The inner casing (2) is provided with a venturi tube (5). The distance between the smallest inner diameter of the venturi tube (5) and the end of the first diverter tube (21) is greater than or equal to 20 mm and less than or equal to 30 mm, so that the air velocity in the first air channel is greater than or equal to 50 m / s and less than or equal to 60 m / s.

11. The heavy-duty gas turbine according to claim 10, characterized in that, The inner casing (2) is provided with multiple rows of air passages (26) along its axial direction. The inner wall of the inner casing (2) is provided with annular baffles (25) corresponding to each row of air passages (26). The annular baffles (25) are used to change the airflow direction entering the inner casing (2) through the corresponding air passages (26) so that the air can flow in contact with the inner wall surface of the inner casing (2) and the inner wall surface of the venturi tube (5).

12. A method of using a heavy-duty gas turbine, characterized in that, The method is applied to the heavy-duty gas turbine as described in claim 8; the operating conditions of the heavy-duty gas turbine include low operating condition, medium operating condition, and high operating condition; when the heavy-duty gas turbine is in low operating condition, the output power of the heavy-duty gas turbine is less than or equal to 0.30 times the rated power; when the heavy-duty gas turbine is in medium operating condition, the output power of the heavy-duty gas turbine is greater than 0.30 times the rated power and less than or equal to 0.80 times the rated power; when the heavy-duty gas turbine is in high operating condition, the output power of the heavy-duty gas turbine is greater than 0.80 times the rated power and less than or equal to 1.09 times the rated power; the method of use includes: When the heavy-duty gas turbine is in a low operating condition, the first fuel ratio is equal to 100%; the first fuel ratio is the proportion of the amount of fuel supplied to the edge combustion zone (11) by each premixed combustion nozzle (31) of the heavy-duty gas turbine to the total amount of fuel supplied to the combustion chamber. When the heavy-duty gas turbine is in medium operating condition, the first fuel ratio is greater than or equal to 60% and less than or equal to 65%; the second fuel ratio is greater than or equal to 35% and less than or equal to 40%; the second fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone (12) by the diffusion combustion nozzle (32) of the heavy-duty gas turbine to the total amount of fuel supplied to the combustion chamber; and the sum of the first fuel ratio and the second fuel ratio is equal to 100%; When the heavy-duty gas turbine is under high operating conditions, the first fuel ratio is 83% and the second fuel ratio is 17%.

13. The method of using the heavy-duty gas turbine according to claim 12, characterized in that, When the heavy-duty gas turbine switches from medium operating condition to high operating condition, the method includes: The first fuel ratio is gradually reduced until it is 0; and while reducing the first fuel ratio, the third fuel ratio is gradually increased, with the decrease in the first fuel ratio being the same as the increase in the third fuel ratio; the third fuel ratio is the proportion of the amount of fuel supplied to the central combustion zone (12) by the heavy-duty gas turbine through the switching pipe (324) to the total amount of fuel supplied to the combustion chamber. After the first fuel ratio is reduced to 0 and the flame between the inner casing (2) and the first splitter pipe (21) is extinguished, the state of the heavy-duty gas turbine is maintained for a preset time. After the heavy-duty gas turbine is maintained in a state for a preset time, the first fuel ratio is gradually increased while the second and third fuel ratios are decreased until the first fuel ratio increases to 83%, the second fuel ratio decreases to 17%, and the third fuel ratio decreases to 0.

14. The method of using the heavy-duty gas turbine according to claim 13, characterized in that, The method further includes: When the output power of the heavy-duty gas turbine is less than or equal to 0.7 times the rated power, the opening of the compressor inlet guide vanes shall be maintained at 35%. When the output power of the heavy-duty gas turbine is greater than 0.7 times the rated power and less than or equal to 1.0 times the rated power, the opening degree of the compressor inlet guide vanes shall be adjusted according to the following calculation formula: in, This indicates the opening degree of the compressor inlet guide vanes when the output power of the heavy-duty gas turbine is equal to t times the rated power; This indicates that the output power of the heavy-duty gas turbine is equal to t times its rated power; When the output power of the heavy-duty gas turbine is greater than 1.0 times the rated power, the opening of the compressor inlet guide vanes is maintained at 100%.

Images