Low-emission combustion chamber for ammonia gas turbine with in-wall pyrolysis

Abstract

This invention provides a low-emission combustion chamber for an ammonia gas turbine with in-wall pyrolysis, relating to the field of ammonia gas turbine technology. It includes a flame tube and nozzles. The flame tube includes an inner shell and an outer shell. The inner shell defines a combustion zone, and the outer shell is fitted outside the inner shell, forming an annular flow channel between them. A catalytic unit is disposed within the annular flow channel to catalytically pyrolyze at least a portion of the ammonia gas passing through the annular flow channel. Based on the airflow direction within the combustion zone, the combustion zone has a sequentially arranged rich fuel zone, quenched fuel zone, and lean fuel zone. The portion of the inner shell located in the rich fuel zone has multiple supplementary fuel holes spaced circumferentially. These supplementary fuel holes connect the annular flow channel to the rich fuel zone, guiding the supplementary fuel generated from ammonia pyrolysis to the rich fuel zone. The nozzles are disposed on the flame tube panel and configured to supply main-path fuel to the combustion zone.

Description

Technical Field

[0001] This invention relates to the field of ammonia gas turbine technology, and more specifically, to a low-pollution combustion chamber for an ammonia gas turbine with in-wall pyrolysis. Background Technology

[0002] Ammonia, as a carbon-free, hydrogen-rich fuel, primarily produces nitrogen and water upon combustion, making it a crucial direction for the low-carbon transformation of gas turbines. Its applications include blending with natural gas or using it as a single primary fuel. However, when used as a primary fuel, ammonia suffers from slow flame propagation, high ignition temperature, poor combustion stability, and high nitrogen oxide emissions, hindering its application. Existing technologies often optimize ammonia combustion through segmented combustion chamber design, the addition of auxiliary gases, or ignition devices. However, these solutions rely on external equipment, are complex to control, have poor adaptability, and increase system costs and space requirements, thus limiting their widespread adoption.

[0003] Therefore, there is an urgent need for an ammonia gas turbine combustor that can improve combustion efficiency, reduce emissions, and has a compact structure. Summary of the Invention

[0004] In view of this, the present invention provides a low-pollution combustion chamber for an ammonia gas turbine with in-wall pyrolysis. It adopts a fuel-rich-quench-lean combustion technology to reduce pollutant emissions, while utilizing the double-layer structure of the flame tube to pyrolyze ammonia gas and injecting the resulting supplementary fuel into the fuel-rich zone, effectively improving combustion stability and expanding the operating range.

[0005] To achieve the above objectives, the present invention provides a low-emission combustion chamber for an ammonia gas turbine with in-wall cracking, comprising a flame tube, an inner shell, and an outer shell. The inner shell defines a combustion zone, and the outer shell is fitted over the inner shell, forming an annular flow channel between them. A catalytic unit is disposed within the annular flow channel to catalytically crack at least a portion of the ammonia passing through the annular flow channel. Depending on the airflow direction within the combustion zone, the combustion zone has a sequentially arranged fuel-rich zone, a quenched zone, and a lean zone. The portion of the inner shell located in the fuel-rich zone is provided with a plurality of supplementary fuel holes spaced circumferentially. These supplementary fuel holes connect the annular flow channel to the fuel-rich zone to guide supplementary fuel generated from ammonia cracking to the fuel-rich zone. A nozzle, disposed on the flame tube panel, is configured to supply main fuel to the combustion zone.

[0006] According to an embodiment of the present invention, the aforementioned supplementary fuel hole is disposed on the portion of the inner shell near the aforementioned flame tube panel, so that at least a portion of the aforementioned supplementary fuel is guided to the corner recirculation zone of the aforementioned fuel-rich zone.

[0007] According to an embodiment of the present invention, the ammonia gas is configured to flow through the annular channel in the opposite direction to the airflow in the combustion zone.

[0008] According to an embodiment of the present invention, it further includes: a first pipeline, wherein the inlet end of the first pipeline is connected to an ammonia gas source, and the outlet end of the first pipeline extends to the tail of the annular flow channel away from the nozzle.

[0009] According to an embodiment of the present invention, the catalyst unit includes a plurality of baffle columns made of nickel-containing metal, the two ends of the baffle columns in the thickness direction being connected to the inner shell and the outer shell respectively; the plurality of baffle columns are arranged at intervals along the axial direction of the annular flow channel to form at least two annular baffle column arrays, and the plurality of baffle columns in each annular baffle column array are arranged at uniform intervals along the circumference of the annular flow channel.

[0010] According to an embodiment of the present invention, the circumferential positions of the aforementioned spoiler columns in at least two adjacent rings of the aforementioned spoiler column array are staggered to form a triangular layout.

[0011] According to an embodiment of the present invention, cooling holes are provided in a portion of the inner shell and the outer shell; the cooling holes penetrate a portion of the turbulence column along the axial direction of the turbulence column.

[0012] According to an embodiment of the present invention, the quenching zone is configured as a venturi tube structure; the portion of the quenching zone adjacent to the fuel-rich zone forms a contraction section, the portion of the quenching zone adjacent to the fuel-deficient zone forms an expansion section, and the portion of the quenching zone located between the contraction section and the expansion section forms a throat.

[0013] According to an embodiment of the present invention, the flame tube is provided with at least four mixing holes on the wall surface of the quenching zone, and the at least four mixing holes are evenly spaced along the circumference of the quenching zone; the mixing holes are configured to extend tangentially along the quenching zone, and are suitable for injecting quenching air tangentially into the quenching zone to apply circumferential momentum to the flue gas from the combustion-rich zone, and the swirl direction of the quenching air jet determined by the mixing holes is consistent with the swirl direction of the main combustion stage cyclone of the nozzle.

[0014] According to an embodiment of the present invention, the nozzle includes a pre-combustion stage and a main combustion stage, the pre-combustion stage and the main combustion stage being coaxially arranged from the inside to the outside; the pre-combustion stage includes a pre-combustion stage channel and a pre-combustion stage cyclone disposed around the pre-combustion stage channel, and a nozzle orifice is provided at the front end of the pre-combustion stage channel; the main combustion stage includes at least two main combustion stage channels and a main combustion stage cyclone disposed around the main combustion stage channels, the at least two main combustion stage channels being arranged around the pre-combustion stage and being centrally symmetrical; the nozzle further includes a cone cover covering the downstream side of the pre-combustion stage.

[0015] The low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided by this invention involves the main fuel being injected through nozzles and then mixed with insufficient air in the fuel-rich zone for combustion, suppressing flame temperature and reducing the formation of thermal nitrogen oxides. Subsequently, the flue gas enters a quenching zone for rapid cooling, causing intermediate products from ammonia decomposition to be oxidized into nitrogen under low-temperature, oxygen-rich conditions, preventing further conversion into nitrogen oxides. Stable combustion is then achieved in the lean zone, ensuring that residual fuel and intermediate products are fully converted into nitrogen and water. Furthermore, some ammonia undergoes catalytic pyrolysis in the annular channel to generate supplementary fuel containing hydrogen, nitrogen, and residual ammonia, which enters the fuel-rich zone through supplementary fuel orifices. Hydrogen enhances flame propagation speed and stability, broadening the flammability limit of ammonia fuel; unpyrolyzed ammonia regulates fuel distribution; and nitrogen dilutes oxygen concentration and helps suppress nitrogen oxide formation. By combining fuel-rich-quenching-lean combustion technology with the double-layer structure of the flame tube itself to achieve ammonia pyrolysis, the stability of ammonia combustion and the combustion efficiency are effectively improved without complex additional equipment, reducing pollutant emissions and facilitating cost control and widespread adoption. Attached Figure Description

[0016] Figure 1 This is a first cross-sectional view of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention;

[0017] Figure 2 This is a partial perspective view of the flame tube of a low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention, with part of the outer shell removed;

[0018] Figure 3 This is a second cross-sectional view of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention;

[0019] Figure 4 This is a partially enlarged view of the catalytic unit of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention;

[0020] Figure 5 This is a third cross-sectional view of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention;

[0021] Figure 6 This is a cross-sectional view of the nozzle of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention.

[0022] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0023] 1. Flame tube;

[0024] 11. Inner shell;

[0025] 111. Fuel-rich area;

[0026] 112. Quenching zone;

[0027] 113. Areas with scarce fuel resources;

[0028] 114. Replenish fuel port;

[0029] 12. Outer shell;

[0030] 13. Catalytic unit;

[0031] 131. Baffle column;

[0032] 14. Flame tube panel;

[0033] 15. Cooling holes;

[0034] 16. Mixing pores;

[0035] 2. Nozzle;

[0036] 21. Pre-combustion stage channel;

[0037] 22. Pre-combustion stage cyclone separator;

[0038] 23. Main combustion stage passage;

[0039] 24. Main combustion stage cyclone separator;

[0040] 25. Cone shield;

[0041] 3. First pipeline;

[0042] 4. Second pipeline;

[0043] 5. Casing. Detailed Implementation

[0044] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0046] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0047] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0048] A gas turbine is a thermal engine that converts the chemical energy of fuel into mechanical energy. When using ammonia as the primary fuel, related technologies mainly address a series of problems related to ammonia combustion by optimizing the combustion organization. For example, segmenting the combustion chamber and adding auxiliary gases or configuring auxiliary ignition devices can improve ammonia combustion efficiency and reduce nitrogen oxide emissions. However, this requires precise coordination with external equipment, making control difficult, resulting in poor adaptability to changes in gas turbine operating conditions, increased space requirements, and higher manufacturing and operating energy consumption, hindering widespread adoption. Therefore, this invention provides a combustion chamber structure for an ammonia gas turbine that improves combustion efficiency, reduces nitrogen oxide emissions, and addresses at least some of the aforementioned technical shortcomings.

[0049] Figure 1 This is a first cross-sectional view of the low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention. Figure 2 This is a partial perspective view of the flame tube of a low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention, with part of the outer shell removed.

[0050] Embodiments of the present invention provide a low-emission combustion chamber for an ammonia gas turbine with in-wall pyrolysis, such as... Figure 1 and Figure 2As shown, the device includes a flame tube 1 and a nozzle 2. The flame tube 1 includes an inner shell 11 and an outer shell 12. The inner shell 11 defines a combustion zone, and the outer shell 12 is fitted outside the inner shell 11, forming an annular flow channel between them. A catalytic unit 13 is disposed within the annular flow channel to catalytically crack at least a portion of the ammonia gas passing through the annular flow channel. Based on the airflow direction within the combustion zone, the combustion zone has a sequentially arranged rich fuel zone 111, a quenching zone 112, and a lean fuel zone 113. The portion of the inner shell 11 located in the rich fuel zone 111 has multiple circumferentially spaced supplementary fuel holes 114. These supplementary fuel holes 114 connect the annular flow channel to the rich fuel zone 111 to guide the supplementary fuel generated from ammonia cracking to the rich fuel zone 111. The nozzle 2 is disposed on the flame tube panel 14 and configured to supply main fuel to the combustion zone.

[0051] like Figure 1 As shown, the flame tube 1 and nozzle 2 are installed inside the housing 5. The flame tube panel 14 is fixedly connected to the housing 5, and the nozzle 2 is located on one side of the flame tube panel 14, i.e. Figure 1 It is positioned above the flame tube panel 14 and is mounted via the flame tube panel 14 and the end cover of the casing 5. Simultaneously, it is combined with... Figure 2 As shown, both the inner shell 11 and the outer shell 12 are constructed as hollow cylindrical structures, nested and installed on the other side of the flame tube panel 14, i.e. Figure 1 Below the central flame tube panel 14, the nozzle 2, inner shell 11, and outer shell 12 are arranged coaxially.

[0052] In this implementation, the main fuel ejected from nozzle 2 is mixed with air and ignited. Since the amount of air mixed is less than theoretically required, incomplete combustion occurs in the fuel-rich zone 111, thereby suppressing flame temperature and reducing the formation of thermal nitrogen oxides. The flue gas generated in the fuel-rich zone 111 reaches the quenching zone 112, where air is rapidly incorporated to cool it down. This causes the intermediate products of ammonia decomposition, such as NH2, HCN, and NH, to be oxidized into nitrogen under low-temperature, oxygen-rich conditions, preventing further conversion into nitrogen oxides. Subsequently, it enters the lean-fuel zone 113 for stable combustion, aiming to convert the ammonia fuel and residual intermediate products into nitrogen and water as much as possible.

[0053] Meanwhile, after at least part of the ammonia in the annular flow channel is catalytically cracked, the resulting mixture of nitrogen, hydrogen, and ammonia as supplementary fuel enters the fuel-rich zone 111 through supplementary fuel holes 114. The circumferentially spaced supplementary fuel holes 114 ensure uniform distribution of the supplementary fuel around the fuel-rich zone, effectively suppressing flame swaying and localized flameout. The high combustion activity of hydrogen further enhances the flame propagation speed and stability in the fuel-rich zone 111, broadening the flammability limit of the main fuel, ammonia. Uncracked ammonia can regulate the fuel concentration distribution in the fuel-rich zone 111. Nitrogen, as an inert medium, can also dilute the oxygen concentration in the fuel-rich zone 111 to a certain extent, helping to suppress the formation of nitrogen oxides. This integration of fuel-rich-quenching-lean combustion technology into the combustion chamber of an ammonia gas turbine, and the use of the double-layer structure of the flame tube 1 itself to assist in stabilizing the combustion flame in the fuel-rich zone 111 through ammonia catalytic cracking, improves the stability of ammonia combustion, reduces pollutant emissions, and, since no complex additional equipment or control procedures are required, also helps to reduce costs and facilitates widespread adoption.

[0054] In some alternative embodiments, such as Figure 1 As shown, the upper end of the flame tube 1 is mounted on the flame tube panel 14, and the lower end is inserted into the inlet of the transition section. The transition section is used to guide the exhaust gas of the flame tube 1 to the downstream turbine. The flame tube 1 can extend and retract along its own axis, and can also expand or contract radially. The radial clearance at the insertion point with the transition section is preferably 1.5 mm. The nozzle 2 is mounted on the end cover of the casing 5 through a flange with a floating ring, and is also inserted into the flame tube panel 14.

[0055] In this implementation, during fuel combustion, the flame tube 1 is constantly exposed to a high-temperature environment above 1000℃, resulting in significant axial thermal elongation and radial thermal expansion. The fixed upper end and plug-in lower end installation provides the flame tube 1 with room for axial expansion and contraction and radial expansion and contraction, effectively releasing thermal stress and preventing failure problems such as cracks and deformation on the flame tube 1 wall. The floating ring can compensate for assembly errors between the end cap and the flame tube panel 14, while also compensating for the differential deformation of various components under high-temperature conditions, ensuring that the nozzle 2 always remains coaxial with the flame tube 1, and avoiding problems such as fuel injection deviation and flame sticking to the wall due to coaxiality deviation.

[0056] In some preferred embodiments, the catalytic unit 13 is made of nickel-containing metal, which enables a high ammonia conversion rate at a relatively low temperature. Even after the heat from the combustion zone is consumed by the inner shell 11 and its surface cooling film, it can still heat the annular flow channel and the catalytic unit 13 to a temperature range with a high ammonia conversion rate.

[0057] In some alternative embodiments, the catalytic unit 13 may also be made of ruthenium-containing metal or iron-containing metal.

[0058] In some alternative embodiments, the radial clearance of the annular flow channel between the inner shell 11 and the outer shell 12 is 3 mm, with a volume of approximately 0.6 L.

[0059] In one exemplary embodiment, such as Figure 1 As shown, the supplementary fuel hole 114 is provided in the part of the inner shell 11 near the flame tube panel 14, so that at least a portion of the supplementary fuel is guided to the corner recirculation area of ​​the fuel-rich zone 111.

[0060] In this implementation, a corner recirculation zone is formed near the corner of the flame tube panel 14 within the fuel-rich zone 111, specifically at the angle between the inner shell 11 and the flame tube panel 14. The airflow velocity in this zone is significantly lower than in the mainstream zone, enabling a stable flame residence point and preventing flame extinction. However, ammonia has low combustion reactivity. If relying solely on the main fuel, the flame in the corner recirculation zone is prone to partial extinction or flickering due to insufficient fuel reactivity. By arranging the supplementary fuel port 114 close to the flame tube panel 14, supplementary fuel (i.e., the mixture of nitrogen, hydrogen, and ammonia) is injected into this corner recirculation zone. The high combustion reactivity of hydrogen enhances the flame propagation speed in the corner recirculation zone, strengthening its flame residence stability. Even under low load and variable operating conditions, a stable flame residence point can be maintained, effectively solving the problem of easy flame extinction in ammonia combustion. Furthermore, after the supplementary fuel is injected into the corner recirculation zone, it can be fully mixed with the main fuel. The low-speed airflow characteristics of the corner recirculation zone extend the mixing time between the main fuel and the supplementary fuel, making the hydrogen and ammonia mixed more evenly. This prevents the supplementary fuel from being quickly carried into the quenching zone 112 by the high-speed airflow, thereby improving the utilization rate of the supplementary fuel.

[0061] In one exemplary embodiment, such as Figure 1 As shown, ammonia is configured to flow through an annular channel in the opposite direction to the airflow in the combustion zone.

[0062] In this embodiment, the high-temperature gas flow in the combustion zone sequentially flows through the fuel-rich zone 111, the quenching zone 112, and the fuel-lean zone 113, in a co-current flow (e.g., Figure 1 As shown from top to bottom), the flow direction of ammonia gas in the annular channel is opposite to the flow direction of the high-temperature gas, i.e., countercurrent flow (as shown in the diagram). Figure 1 (As shown from bottom to top). When the high-temperature gas flows in the forward direction, it conducts heat to the annular channel through the inner shell 11. Meanwhile, the ammonia gas flows in the reverse direction through the annular channel, entering from the low-temperature end of the annular channel (the end closer to the lean combustion zone 113). It gradually absorbs the heat conducted by the inner shell 11 along the reverse direction, and the temperature gradually increases until it reaches the high-temperature end of the annular channel (the end closer to the rich combustion zone 111). The catalytic cracking efficiency also gradually increases, so as to provide supplementary fuel with a higher hydrogen content to the rich combustion zone 111 through the supplementary fuel hole 114, thereby enhancing the flame stability.

[0063] In some optional embodiments, the catalytic unit 13 can be divided into three functional sections along the counter-current direction of the annular flow channel based on temperature distribution: a low-temperature catalytic section near the lean combustion zone 113, a high-temperature catalytic section near the rich combustion zone 111, and a medium-temperature catalytic section located between the two. It should be understood that the above segmentation is mainly based on the gradually changing temperature field within the annular flow channel, and there are no absolute physical boundaries between the sections. Accordingly, since the cracking reaction is endothermic, to avoid the forced cracking of ammonia leading to a sudden temperature change that affects the lifespan of the catalytic unit 13, a low-activity nickel-based catalyst is selected for the low-temperature catalytic section, a medium-activity nickel-ruthenium composite catalyst is selected for the medium-temperature catalytic section, and a high-activity ruthenium-based catalyst is selected for the high-temperature catalytic section.

[0064] In one exemplary embodiment, such as Figure 1 and Figure 2 As shown, the aforementioned low-pollution combustion chamber of the ammonia gas turbine with in-wall pyrolysis also includes a first pipeline 3. The inlet end of the first pipeline 3 is connected to an ammonia gas source, and the outlet end of the first pipeline 3 extends to the tail of the annular flow channel away from the nozzle 2.

[0065] In this embodiment, the first pipe 3 is arranged parallel to the flame tube 1, with one end passing through the flame tube panel 14 and connected to the ammonia gas source, and the other end connected to the tail of the annular flow channel (i.e., Figure 1 Connected to the lower end of the annular flow channel, ammonia from the ammonia gas source can be directly transported to the tail end of the annular flow channel, ensuring that the ammonia fully participates in countercurrent heat exchange from the low-temperature end, gradually absorbing the heat conducted by the inner shell 11 to raise the temperature, and avoiding the mixing of ammonia midway, which would cause disturbances in the temperature and pressure fields within the annular flow channel. At the same time, the directional delivery design can stabilize the ammonia supply flow rate, providing a uniform reactant basis for the catalytic unit 13 and ensuring stable cracking efficiency.

[0066] Figure 3 This is a second cross-sectional view of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention.

[0067] In some alternative embodiments, such as Figure 3 As shown, the low-pollution combustion chamber of the ammonia gas turbine with in-wall pyrolysis also includes a second pipeline 4. The inlet end of the second pipeline 4 is connected to the gas distribution source, and the outlet end of the second pipeline 4 is connected to the fuel-rich zone 111. The connection position is close to the supplementary fuel hole 114.

[0068] In such an implementation, such as Figure 3 As shown, the second pipe 4 is arranged parallel to the first pipe 3. One end of the second pipe 4 passes through the flame tube panel 14 and is connected to the gas distribution source, while the other end is connected to the head of the annular flow channel (i.e., Figure 2Connected to the upper end of the annular flow channel, the gas supply source outputs pure hydrogen or simulated cracked gas according to a preset nitrogen and hydrogen ratio, which is directly injected into the corner reflux zone through the second pipeline 4. When testing the combustion chamber structure, the first pipeline 3 can be closed, and pure hydrogen or simulated cracked gas according to a preset nitrogen and hydrogen ratio can be directly supplied to the corner reflux zone through the second pipeline 4. This can skip the complex process of ammonia catalytic cracking, quickly establish a stable combustion atmosphere, significantly shorten the test cycle, and reduce the time cost caused by cracking system debugging during the test.

[0069] like Figure 2 As shown, the inner shell 11 and the outer shell 12 have annular flanges at the ends near the flame tube panel. Multiple waist-shaped holes and multiple round holes are opened on the annular flanges. The waist-shaped holes are used to allow external air to enter the nozzle 2 through the annular cavity between the outer shell 12 and the casing 5. A portion of the multiple round holes are connected to the first pipe 3, and another portion is connected to the second pipe.

[0070] For example, the oblong holes and round holes include, but are not limited to, four of each. Correspondingly, the first pipe 3 and the second pipe 4 include, but are not limited to, two of each, and are evenly spaced along the circumferential direction of the outer shell 12, and are connected to each round hole respectively.

[0071] In some other embodiments, the second pipeline 4 can also be opened during the ignition and start-up phase of the ammonia gas turbine. During this phase, the combustion chamber temperature is low, the catalytic unit 13 has insufficient activity, and the ammonia cracking efficiency is low, failing to provide sufficient supplementary fuel to the rich fuel zone 111. Opening the second pipeline 4 at this time allows for direct gas distribution, rapidly increasing fuel activity in the corner recirculation zone, reducing ignition energy requirements, and improving ignition success rate. Simultaneously, it avoids the generation of large amounts of intermediate products due to incomplete combustion during the start-up phase, effectively reducing nitrogen oxide and unburned pollutant emissions during this stage.

[0072] According to embodiments of this disclosure, during the ignition start-up phase, the gas supply can also be directly introduced into the nozzle 2 to further improve the ignition success rate.

[0073] Figure 4 This is a partially enlarged view of the catalytic unit of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention.

[0074] In one exemplary embodiment, such as Figure 1 , Figure 2 and Figure 4As shown, the catalytic unit 13 includes a plurality of baffle columns 131 made of nickel-containing metal. The two ends of the baffle columns 131 in the thickness direction are respectively connected to the inner shell 11 and the outer shell 12. The plurality of baffle columns 131 are arranged at intervals along the axial direction of the annular flow channel to form at least two annular baffle column arrays. The plurality of baffle columns 131 in each annular baffle column array are evenly spaced along the circumference of the annular flow channel.

[0075] In this embodiment, the turbulence column 131 is supported between the inner shell 11 and the outer shell 12, and the distance between the inner shell 11 and the outer shell 12 is the thickness of the turbulence column 131. Multiple turbulence columns 131 are simultaneously arranged at uniform intervals along the axial and circumferential directions of the annular flow channel to form a multi-ring annular turbulence column array.

[0076] When ammonia gas flows through the annular channel, it comes into full contact with the multi-ring array of turbulence columns, undergoing a cracking reaction under the catalytic action of metallic nickel to generate hydrogen and nitrogen. Simultaneously, the array arrangement of the turbulence columns 131 breaks the laminar flow of ammonia, creating localized turbulence, extending the residence time of ammonia within the channel, and improving gas-solid contact efficiency. The two ends of the turbulence columns 131 are directly connected to the inner shell 11 and the outer shell 12, allowing for rapid heat transfer from the combustion zone absorbed by the inner shell 11. This ensures that the surface temperature of the turbulence columns 131 is uniformly maintained within the optimal range for ammonia cracking, eliminating the need for additional heating. Combined with the array arrangement, this creates a uniform temperature field, preventing localized overheating or low-temperature dead zones, ensuring stable catalytic activity, and simultaneously enhancing the heat exchange efficiency between the inner shell 11 and the outer shell 12, thereby improving energy utilization.

[0077] It is understandable that, regardless of whether the baffle column 131 is constructed as a cylinder, prism, or other columnar structure, the thickness direction of the baffle column 131 is one of the radial directions of the annular flow channel, and this radial direction passes through the geometric center of the baffle column 131.

[0078] According to an embodiment of the present invention, the circumferential positions of the spoiler columns 131 in at least two adjacent rings of spoiler column arrays are staggered to form a triangular layout.

[0079] In such an implementation, such as Figure 2 and Figure 4As shown, the circumferential positions of the turbulence columns 131 in two adjacent rings of turbulence column arrays are staggered, so that the axial projection of each turbulence column 131 in the upper ring is located between the two closest turbulence columns 131 in the lower ring. These three turbulence columns 131 form a triangular layout, which can more effectively break the laminar flow state of ammonia in the annular channel. When ammonia flows through the multi-ring turbulence column array, the airflow disturbance formed by the previous ring of turbulence columns 131 is further dispersed by the staggered turbulence columns 131 in the next ring, forming a multi-directional interwoven three-dimensional turbulent field, rather than a single-directional airflow deflection. This turbulence effect not only significantly prolongs the residence time of ammonia in the annular channel, but also forces the ammonia to flow around through the gaps in the triangular layout, increasing the collision frequency with the surface of the turbulence columns 131, improving the sufficiency and uniformity of gas-solid contact, avoiding localized excessively high flow velocities or stagnant dead zones in the annular channel, and ensuring that every part of the ammonia can fully contact the surface of the turbulence columns 131.

[0080] In addition, the triangular layout has excellent stress stability. The multi-ring staggered baffle column array can evenly distribute the airflow pressure in the annular flow channel to each baffle column 131, inner shell 11 and outer shell 12. At the same time, it can also improve the support of the inner shell 11 and outer shell 12, avoid structural deformation caused by stress concentration in a single area, and improve the structural reliability of the flame tube 1 under high temperature and high pressure conditions.

[0081] In some preferred embodiments, the circumferential misalignment distance of the spoiler columns 131 in two adjacent spoiler column arrays is equal to half the circumferential spacing between the two adjacent spoiler columns 131.

[0082] In a more preferred embodiment, the triangular layout is further constructed as an equilateral triangle layout.

[0083] In some other embodiments, the axial spacing between two adjacent rings of spoiler columns is equal to the circumferential spacing between two adjacent spoiler columns 131.

[0084] In some alternative embodiments, the shape of the turbulence column 131 includes, but is not limited to, cylindrical or prismatic shapes, such as... Figure 2As shown, two types of baffle columns 131 are arranged between the inner shell 11 and the outer shell 12. The one near the supplementary fuel port 114 is a cylindrical baffle column 131. With approximately the same volume, the cylindrical one has a larger surface area, resulting in more thorough contact with the ammonia gas. The remaining part is a prismatic baffle column 131. Prisms are relatively easier to manufacture, which is beneficial for large-area arrangement. The thickness direction of the prismatic baffle column 131 is the same as that of the cylindrical baffle column 131, which is the radial direction of the annular flow channel passing through the geometric center of the baffle column 131. The length direction of the prismatic baffle column 131 is the axial direction of the flame tube 1. Since its two ends in the thickness direction are connected to the inner shell 11 and the outer shell 12 respectively, the width direction of the prismatic baffle column 131 can be approximately regarded as the direction of the inner shell 11 / outer shell 12.

[0085] In some optional embodiments, the diameter of the cylindrical turbulence column 131 is 1 mm, the center distance between adjacent turbulence columns 131 is 1.5 mm, the characteristic flow velocity of ammonia in the annular channel is 16.1 m / s, and the residence time is about 21.7 ms.

[0086] In one exemplary embodiment, such as Figure 2 and Figure 4 As shown, cooling holes 15 are provided in a portion of the inner shell 11 and the outer shell 12. The cooling holes 15 penetrate a portion of the baffle column 131 along its axial direction.

[0087] Further integration Figure 1 , Figure 2 and Figure 4 As shown, multiple cooling holes 15 are arranged at intervals along the axial direction of the inner shell 11 / outer shell 12 to form a multi-ring annular cooling hole array. In each ring of the cooling hole array, multiple cooling holes are evenly spaced along the circumferential direction of the inner shell 11 / outer shell 12.

[0088] In this embodiment, the cooling hole 15 directly connects the annular cavity between the outer shell 12 and the casing 5 and the combustion zone. This allows the cooling medium (preferably compressed air from the compressor outlet) to enter the annular cavity without flowing into the annular flow channel used for pyrolysis. Instead, it passes through the cooling hole 15 sequentially through the outer shell 12, the baffle column 131, and the inner shell 11 into the combustion zone. This suppresses the flame in the combustion zone from adhering to the wall, reduces local overheating of the inner shell 11 wall, and improves the structural stability of the flame tube 1. Furthermore, since the cooling medium flows through the interior of the baffle column 131, it can carry away some of the heat from the baffle column 131, maintaining the temperature of the baffle column 131 within a temperature range with high pyrolysis efficiency, thus extending the service life of the baffle column.

[0089] In some preferred embodiments, such as Figures 1 to 3 As shown, the cooling holes 15 are arranged to cover the fuel-rich zone 111 and part of the quenching zone 112. The specific arrangement of the cooling holes 15 is determined based on the baffle column 131, for example... Figures 1 to 3 In the middle, the prismatic baffle column 131 is configured to have two lengths. At the position corresponding to the first length (shorter length), the cooling hole array is configured in 3 circles, and at the position corresponding to the second length (longer length), the cooling hole array is configured in 7 circles.

[0090] In some alternative embodiments, such as Figure 1 or Figure 3 As shown, when the turbulence column 131 is prismatic, the cooling hole 15 is constructed as an oblique hole, and its axis has an acute angle with the thickness direction of the turbulence column 131. In other words, the inlet of the cooling hole 15 is close to the nozzle 2, while the outlet is relatively far away from the nozzle 2, so as to facilitate the flow of the cooling medium adhering to the inner wall surface of the inner shell 11 after entering the combustion zone.

[0091] In one exemplary embodiment, such as Figures 1 to 3 As shown, the quenching zone 112 is configured as a Venturi tube structure. The portion of the quenching zone 112 adjacent to the fuel-rich zone 111 forms a contraction section, the portion of the quenching zone 112 adjacent to the fuel-deficient zone 113 forms an expansion section, and the portion of the quenching zone 112 located between the contraction section and the expansion section forms a throat.

[0092] The quenching zone 112, along with the airflow direction within the combustion zone, sequentially forms a contraction section, a throat, and an expansion section. In the contraction section, the inner shell 11 wall gradually contracts inward along the airflow direction, causing the flow cross-section to gradually decrease. In the expansion section, the inner shell 11 wall gradually expands outward along the airflow direction, causing the flow cross-section to gradually increase. The throat is the part of the quenching zone 112 with the smallest flow cross-section, i.e., the core throttling structure of the venturi tube.

[0093] In this implementation, the flue gas generated in the fuel-rich zone 111 enters the contraction section, and its velocity gradually increases as the flow cross-section decreases, reaching its maximum velocity at the throat. The high-speed airflow creates a local negative pressure at the throat, actively drawing in external cold air without the need for additional power. The cold air and flue gas mix violently, and within the expansion section, the velocity decreases as the flow cross-section increases, and the mixing time is prolonged, causing the flue gas temperature to rapidly drop to the target range within a short distance, completing the quenching process. This suppresses the formation of thermal nitrogen oxides and simultaneously promotes the rapid oxidation of intermediate products such as NH2, HCN, and NH generated in the fuel-rich zone 111 into nitrogen gas under low-temperature, oxygen-rich conditions, blocking their conversion pathway to nitrogen oxides and reducing pollutant emissions at the source. After quenching, the flue gas gradually decelerates and stabilizes in the expansion section, forming a uniform and stable airflow field. This provides favorable airflow conditions for the complete and stable combustion in the subsequent lean zone 113, avoiding flame swaying or incomplete combustion caused by airflow turbulence.

[0094] Figure 5 This is a third cross-sectional view of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention.

[0095] According to embodiments of the present invention, such as Figure 1 and Figure 5 As shown, the flame tube 1 has at least four mixing holes 16 on the wall of the quenching zone 112, and the at least four mixing holes 16 are evenly spaced along the circumference of the quenching zone 112. The mixing holes 16 are configured to extend tangentially along the quenching zone 112, suitable for tangentially injecting quenched air into the quenching zone 112 to apply circumferential momentum to the flue gas from the fuel-rich zone 111. The swirl direction of the quenched air jet determined by the mixing holes 16 is consistent with the swirl direction of the main combustion stage cyclone of the nozzle 2.

[0096] In this implementation, the quenched air, after being injected through the tangentially extended mixing hole 16, moves along the tangential direction of the inner wall of the quenching zone 112, possessing a circumferential velocity component. This facilitates the penetration of the flow boundary layer, allowing the flue gas in the central region to be rapidly entrained and mixed with the surrounding quenched air. The strong mixing effect of the rotating jet can quickly level the temperature and oxygen concentration gradients within the quenching zone 112, causing the flue gas temperature to uniformly drop to the target range. This suppresses the formation of thermal nitrogen oxides and provides a uniform low-temperature, oxygen-rich environment for the intermediate products generated in the fuel-rich zone 111, promoting their efficient oxidation into nitrogen. Furthermore, the rotating airflow generated by the main combustion stage cyclone of nozzle 2 is crucial for maintaining the flame stability in the fuel-rich zone 111. The jet rotation direction of the mixing hole 16 is consistent with that of the main combustion stage cyclone, allowing the rotating flue gas flowing out of the fuel-rich zone 111 to enter the quenching zone 112 and smoothly connect with the rotating jet of quenched air. This avoids the collision of two opposing rotating airflows, preventing the formation of a vortex dead zone and reducing airflow pressure loss and turbulent dissipation.

[0097] In some other embodiments, the number of mixing holes 16 may also be 6 or 8, so that the quenching air supply and the rotating jet flow rate have a wider range of adjustment.

[0098] In some preferred embodiments, the swirl number of the formed rotating jet is approximately 0.42.

[0099] Figure 6 This is a cross-sectional view of the nozzle of the low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis provided in an embodiment of the present invention.

[0100] In one exemplary embodiment, such as Figure 1 and Figure 6 As shown, nozzle 2 includes a pre-combustion stage and a main combustion stage, which are coaxially arranged from the inside out. The pre-combustion stage includes a pre-combustion stage channel 21 and a pre-combustion stage swirler 22 disposed around the pre-combustion stage channel 21. A nozzle orifice is provided at the front end of the pre-combustion stage channel 21. The main combustion stage includes at least two main combustion stage channels 23 and a main combustion stage swirler 24 disposed around the main combustion stage channels 23. The at least two main combustion stage channels 23 are arranged around the pre-combustion stage and are centrally symmetrical. Nozzle 2 also includes a conical shroud 25 covering the downstream side of the pre-combustion stage.

[0101] In this implementation, the pre-combustion stage channel 21 is located at the center of the nozzle 2, and a gas channel surrounds the pre-combustion stage channel 21. The pre-combustion stage swirler 22 is located at the end of the gas channel. During combustion chamber startup and low-load conditions, the ammonia fuel in the pre-combustion stage channel 21 is ejected through the nozzle and mixed with air from the gas channel within the cone shroud 25, quickly forming a continuous and stable standby flame that resides within the cone shroud 25. The cone shroud 25 can prevent the flue gas backflow from the combustion zone from scouring the nozzle, while also constraining the diffusion range of the standby flame, making the flame shape more concentrated and improving the ignition efficiency of the main combustion stage fuel. Furthermore, the cone shroud 25 can also guide the airflow to form a local backflow zone, further enhancing flame stability and solving the problems of high ignition energy requirements for ammonia fuel and easy flame extinguishing under low load.

[0102] The main combustion stage starts at medium to high loads. At least two main combustion stage channels 23 are arranged around the gas passage. The ends of the two main combustion stage channels 23 converge through an annular chamber. The ammonia fuel in the main combustion stage channels 23 is fully mixed with air from the main combustion stage cyclone separator 24 to form a swirl. Under the ignition of the standby flame, it achieves fuel-rich premixed combustion, forming an inner and outer nested combustion field with the standby flame as the boundary of the cone shroud 25. This optimizes the temperature distribution in the combustion zone and balances combustion efficiency and pollutant control. Based on this, supplementary fuel output from the supplementary fuel port 114 forms a three-stage fuel path control, which is beneficial for matching the variable load of the ammonia gas turbine and achieving efficient and stable combustion over a wide range.

[0103] In some alternative embodiments, the pre-combustion stage and the main combustion stage can be supplied separately or in combination, and corresponding combustion adjustment strategies can be formulated according to the characteristics of the ammonia gas turbine to improve the load adaptability of the combustion chamber.

[0104] Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention can be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0105] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. An ammonia gas turbine low emission combustor with in- wall dissociation, characterized by, include: A flame tube includes an inner shell and an outer shell. The interior of the inner shell defines a combustion zone. The outer shell is fitted outside the inner shell and forms an annular flow channel with the inner shell. A catalytic unit is disposed in the annular flow channel so that at least a portion of the ammonia gas passing through the annular flow channel is catalytically cracked. Based on the airflow direction in the combustion zone, the combustion zone has a sequentially arranged fuel-rich zone, quenching zone, and lean-fuel zone. The portion of the inner shell located in the fuel-rich zone is provided with multiple supplementary fuel holes spaced apart along the circumference. The supplementary fuel holes connect the annular flow channel to the fuel-rich zone to guide the supplementary fuel generated by ammonia cracking to the fuel-rich zone. The nozzle, located on the flame tube panel, is configured to supply main-path fuel to the combustion zone.

2. The low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 1, characterized in that, The replenishment fuel hole is located on the inner shell near the flame tube panel, so that at least a portion of the replenishment fuel is guided to the corner recirculation zone of the fuel-rich zone.

3. The low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis as described in claim 1, characterized in that, The ammonia gas is configured to flow through the annular channel in the opposite direction to the airflow in the combustion zone.

4. The low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 3, characterized in that, Also includes: The first pipeline has an inlet end connected to an ammonia gas source and an outlet end extending to the tail of the annular flow channel away from the nozzle.

5. The low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 1, characterized in that, The catalytic unit includes a plurality of baffle columns made of nickel-containing metal, and the two ends of the baffle columns in the thickness direction are respectively connected to the inner shell and the outer shell; Multiple of the aforementioned baffle columns are arranged at axial intervals along the annular flow channel to form at least two annular baffle column arrays, wherein multiple baffle columns in each annular baffle column array are arranged at uniform intervals along the circumference of the annular flow channel.

6. The low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 5, characterized in that, The circumferential positions of the spoiler columns in at least two adjacent rings of the spoiler column array are staggered to form a triangular layout.

7. The low-pollution combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 5, characterized in that, Cooling holes are provided in certain areas of the inner shell and the outer shell; The cooling hole extends through a portion of the turbulence column along its axial direction.

8. The low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 1, characterized in that, The quenching zone is configured as a Venturi tube structure; The portion of the quenching zone adjacent to the fuel-rich zone forms a contraction section, the portion of the quenching zone adjacent to the fuel-deficient zone forms an expansion section, and the portion of the quenching zone located between the contraction section and the expansion section forms a throat.

9. The low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 8, characterized in that, The flame tube is provided with at least four mixing holes on the wall of the quenching zone, and the at least four mixing holes are evenly spaced along the circumference of the quenching zone. The mixing orifice is configured to extend tangentially along the quenching zone, suitable for tangentially injecting quenching air into the quenching zone to apply circumferential momentum to the flue gas from the fuel-rich zone. The direction of the quenched air jet determined by the mixing orifice is consistent with the direction of the main combustion stage cyclone of the nozzle.

10. The low-emission combustion chamber of an ammonia gas turbine with in-wall pyrolysis according to claim 1, characterized in that, The nozzle includes a pre-combustion stage and a main combustion stage, wherein the pre-combustion stage and the main combustion stage are coaxially arranged from the inside to the outside. The pre-combustion stage includes a pre-combustion stage channel and a pre-combustion stage cyclone separator disposed around the pre-combustion stage channel. The front end of the pre-combustion stage channel is provided with a spray hole. The main combustion stage includes at least two main combustion stage channels and a main combustion stage cyclone separator disposed around the main combustion stage channels. The at least two main combustion stage channels are arranged around the pre-combustion stage and are centrally symmetrical. The nozzle also includes a cone-shaped cover positioned downstream of the pre-combustion stage.

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