Gradient type thermocatalytic cracking, rotational flow pre-combustion and flue gas recirculation ammonia burner

Abstract

The invention relates to the technical field of combustor application, in particular to an ammonia combustor with gradient type thermocatalytic cracking, rotational flow pre-combustion and flue gas recirculation functions. The problems that pure ammonia combustion stability is poor, catalytic cracking and combustion coupling is weak, wide-load stable combustion difficulty is large, and NOx emission control cost is high are mainly solved. According to the technical scheme, the device comprises an ammonia ignition combustion-supporting module, a stepped catalyst module, a direct-current rotational flow combined type pre-combustion module, an ammonia main combustion stage module and a flue gas recirculation module which are distributed from inside to outside in the radial direction; the ammonia ignition combustion-supporting module, the stepped catalyst module and the direct-current rotational-flow combined type pre-combustion module are designed in a concentric surrounding mode, and the ammonia ignition combustion-supporting module is located in the center. The pure ammonia wide-load stable combustion is achieved, the ammonia cracking efficiency is improved, the catalyst cost is reduced, rotational flow stable combustion and direct current penetration are coordinated, NOx emission is reduced in situ, the reliability of the device is improved through the integrated design, and construction of a zero-carbon energy system is assisted.

Description

Technical Field

[0001] This invention relates to the field of burner application technology, and in particular to an ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion and flue gas recirculation. Background Technology

[0002] Ammonia, as a highly promising zero-carbon energy carrier, holds significant strategic importance for building new energy systems and achieving deep decarbonization in the power and high-temperature industries. Compared to hydrogen, ammonia offers significant safety and economic advantages in storage and transportation. However, when ammonia is directly used as the primary fuel in combustion devices, its inherent high ignition temperature, narrow combustible range, and low flame propagation speed pose serious challenges to the stable operation of the burner and can easily lead to incomplete combustion and nitrogen oxides (NOx). x Emissions exceeded standards.

[0003] The mainstream technologies for promoting the application of ammonia fuel in existing combustion systems include pure ammonia combustion technology and ammonia-fuel hybrid combustion technology. Although pure ammonia burners can achieve completely zero carbon emissions, they often face problems such as difficulty in ignition, poor flame stability, and the need for additional auxiliary energy to maintain combustion. This not only increases the complexity of the system and the initial investment, but also affects its economy and reliability.

[0004] Against this backdrop, ammonia pretreatment technology based on gradient thermocatalytic cracking has emerged, aiming to efficiently decompose ammonia into a hydrogen-rich mixture before combustion, thereby significantly improving fuel activity. However, existing cracking technologies often face challenges such as catalyst poisoning, large fluctuations in cracking efficiency depending on operating conditions, and poor coupling with combustion organization. Simultaneously, conventional burners struggle to achieve efficient and stable staged ignition of the cracked gas, particularly failing to coordinate the relationship between swirling stable combustion and direct current penetration over a wide load range, limiting their ability to process low-calorific-value cracked gases. Furthermore, the inherent nitrogen content of ammonia molecules and the high temperatures generated during combustion are the main sources of NO during combustion. x The main cause of pollution is the high cost of traditional flue gas treatment technologies (such as SCR), necessitating the development of an in-situ pollutant control method that can be integrated into the combustion process.

[0005] Therefore, we need to develop an integrated ammonia burner that can organically integrate high-efficiency catalytic cracking, swirling DC composite stable combustion, and flue gas recirculation low-NOx technology. Summary of the Invention

[0006] The purpose of this invention is to address the problems in the background technology, such as poor combustion stability of pure ammonia, weak coupling between catalytic cracking and combustion, difficulty in achieving stable combustion under wide loads, and NO... x To address the issue of high emission control costs, an ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation is proposed.

[0007] The technical solution of the present invention: an ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion and flue gas recirculation, comprising an ammonia ignition and combustion-supporting module, a stepped catalyst module, a DC swirl composite pre-combustion module, an ammonia main combustion stage module and a flue gas recirculation module distributed radially from the inside to the outside;

[0008] The ammonia ignition and combustion-supporting module, the stepped catalyst module, and the DC swirl composite pre-combustion module adopt a concentric ring design. The ammonia ignition and combustion-supporting module is located in the center, the ammonia main combustion stage module is distributed in a concentric structure outside the stepped catalyst module and the DC swirl composite pre-combustion module, and the flue gas recirculation module is located on the outermost layer of the concentric structure.

[0009] The inlet ends of the ammonia ignition and combustion-supporting module, the stepped catalyst module, the DC swirl composite pre-combustion module, the ammonia main combustion stage module, and the flue gas recirculation module are arranged sequentially from front to back along the axial direction. The outlet end of the ammonia ignition and combustion-supporting module is located inside the stepped catalyst module, the outlet end of the stepped catalyst module is located inside the DC swirl composite pre-combustion module, the outlet end of the DC swirl composite pre-combustion module is located inside the ammonia main combustion stage module, and the outlet end of the ammonia main combustion stage module is located inside the flue gas recirculation module.

[0010] The ammonia ignition and combustion-supporting module generates a first ammonia flame that acts on the stepped catalyst module. The ammonia gas introduced through cracking is a mixture of ammonia-rich, nitrogen-rich, and hydrogen-rich gas. The DC swirl composite pre-combustion module extracts the cracked gas and ignites it with air to form a second DC standby flame, which, in conjunction with the swirling air, forms a second swirling standby flame. The second swirling standby flame ignites the ammonia gas ejected from the ammonia main combustion stage module, forming a third ammonia flame under the action of the swirling air.

[0011] The flue gas recirculation module extracts high-temperature flue gas and reacts it with the first ammonia flame on the stepped catalyst module.

[0012] Optionally, the ammonia ignition and combustion-supporting module includes a first air inlet, a low-power sliding arc plasma structure, a first ammonia inlet, a second air inlet, a first swirl vane, and a second swirl vane;

[0013] The low-power sliding arc plasma structure consists of a first electrode and a second electrode. The first electrode and the second electrode are connected to a high-voltage power supply. The discharge breaks down the swirling air formed by the first swirling blade, which is used to form a first ammonia flame by introducing ammonia gas through the first ammonia gas inlet.

[0014] The combustion air introduced through the second air inlet is regulated by the second swirl vanes to form an outer swirl.

[0015] Optionally, the stepped catalyst module includes a second ammonia inlet and platinum-based catalyst, ruthenium-based catalyst, and nickel-based catalyst arranged in layers from front to back along the axial direction.

[0016] The platinum-based catalyst is located at the inlet front end and is used for low-temperature rapid ignition and primary pyrolysis;

[0017] The ruthenium-based catalyst is located in the middle section and is used for the directional conversion of intermediate products to suppress side reactions;

[0018] Nickel-based catalysts are located in the later or peripheral stages for deep pyrolysis in high-temperature zones and to maintain long-term catalytic activity.

[0019] Optionally, the layered arrangement of the platinum-based catalyst, ruthenium-based catalyst, and nickel-based catalyst is used to optimize the ratio and position of the precious metal and inexpensive metal catalysts.

[0020] Optionally, the DC swirl composite pre-combustion module includes a standby fuel supply pipe, a standby air supply pipe, a standby flame igniter, a third air inlet, and a fourth swirl blade;

[0021] The duty fuel supply pipe is connected downstream of the stepped catalyst module and is used to extract cracked gas and air from the duty air supply pipe to mix and ignite at the duty flame igniter to form a second DC duty flame.

[0022] The air introduced through the third air inlet passes through the fourth swirl blade to form swirling air, which mixes with the second DC duty flame to form the second swirling duty flame.

[0023] Optionally, the ammonia main combustion stage module includes a third ammonia inlet, a fourth air inlet, an ammonia injection port, and a fifth swirl vane;

[0024] The third ammonia inlet is connected to multiple radially distributed ammonia channels. Ammonia is ejected through the ammonia injection port. Air is introduced through the fourth air inlet and forms a swirling flow through the fifth swirling blade. Ammonia and swirling air mix and form the third ammonia flame through the second swirling flame.

[0025] Optionally, the flue gas recirculation module includes a recirculated flue gas outlet, an air extraction port, a flue gas recirculation pump, a recirculated flue gas inlet, and a fifth air inlet;

[0026] The high-temperature flue gas drawn from the exhaust port is driven by the flue gas circulation pump and reinjected into the stepped catalyst module through the recirculated flue gas inlet.

[0027] The fifth air inlet allows air to be introduced for cooling the burner walls and nozzles.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] This invention employs a staged ignition and stable combustion design using an ammonia ignition and combustion-supporting module and a DC swirl composite pre-combustion module. First, a sliding arc plasma generates the first ammonia flame, and then the pre-combustion module forms a DC and swirl dual-flight flame, providing a high-intensity and high-stability continuous ignition source for the ammonia main combustion stage. This effectively solves the problems of difficult ignition and stable combustion caused by the high ignition temperature, narrow combustible range, and low flame propagation speed of pure ammonia fuel, achieving stable combustion of pure ammonia fuel under a wide range of load conditions.

[0030] A stepped, layered catalyst module is adopted. Through the gradient synergistic effect of platinum-based catalyst for rapid low-temperature ignition, ruthenium-based catalyst for directional conversion to suppress side reactions, and nickel-based catalyst for high-temperature deep cracking, the ammonia cracking efficiency and hydrogen-rich mixed gas yield are significantly improved. At the same time, the optimized layered ratio of precious metal and inexpensive metal catalysts significantly reduces the overall manufacturing cost of the catalyst module while ensuring catalytic performance, and solves the problems of easy catalyst poisoning and large efficiency fluctuations in existing cracking technologies.

[0031] Furthermore, the DC swirl composite pre-combustion module of the present invention ensures the reliability and penetration of the ignition source through the DC standby flame, while the swirl standby flame enhances the mixing and stable combustion effect of fuel and air. The synergistic effect of the two effectively coordinates the contradictory relationship between swirl stable combustion and DC penetration, improves the burner's adaptability to low-calorific-value pyrolysis gas, and ensures stable operation of the device within a wide load range.

[0032] This invention employs a radially concentric, axially nested structure design, organically integrating five functional modules: ammonia ignition and combustion support, gradient catalytic cracking, swirl-flow direct-current pre-combustion, ammonia main combustion, and flue gas recirculation. Each module's outlet is progressively embedded into the downstream module, achieving orderly flow and efficient coupling of fuel, air, and flue gas. The device has a compact structure, occupies little space, and reduces external components such as piping connections, improving system reliability and maintenance convenience. It achieves efficient and clean combustion of ammonia fuel, fully leveraging ammonia's safety and economic advantages over hydrogen in storage and transportation, providing a reliable technical solution for deep decarbonization in power generation, high-temperature industries, and other fields. The device operates with zero carbon emissions and NOx emissions. x With low emissions and significant environmental and economic benefits, it is of great significance for promoting the construction of a new zero-carbon energy system;

[0033] In summary, this invention achieves stable combustion of pure ammonia under wide load conditions, improves ammonia cracking efficiency, reduces catalyst costs, coordinates swirl-based combustion and direct current penetration, and reduces NO emissions in situ. x Integrated design enhances device reliability and contributes to the construction of a zero-carbon energy system. Attached Figure Description

[0034] Figure 1This is a schematic diagram of an ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation.

[0035] Figure label:

[0036] 1. Ammonia ignition and combustion-supporting module; 1-1. First air inlet; 1-2. Low-power sliding arc plasma structure; 1-2-1. First electrode; 1-2-2. Second electrode; 1-3. First ammonia inlet; 1-4. Second air inlet; 1-5. First swirl vane; 1-6. Second swirl vane; 1-7. First ammonia flame;

[0037] 2. Stepped catalyst module; 2-1. Second ammonia inlet; 2-2. Platinum-based catalyst; 2-3. Ruthenium-based catalyst; 2-4. Nickel-based catalyst;

[0038] 3. DC swirl composite pre-combustion module; 3-1. On-duty fuel supply pipe; 3-2. On-duty air supply pipe; 3-3. On-duty flame igniter; 3-4. Third air inlet; 3-5. Fourth swirl blade; 3-6. Second DC on-duty flame; 3-7. Second swirl on-duty flame;

[0039] 4. Ammonia main combustion stage module; 4-1. Third ammonia inlet; 4-2. Fourth air inlet; 4-3. Ammonia injection port; 4-4. Fifth swirl vane; 4-5. Third ammonia flame;

[0040] 5. Flue gas recirculation module; 5-1. Recirculated flue gas outlet; 5-2. Air extraction port; 5-3. Flue gas recirculation pump; 5-4. Recirculated flue gas inlet; 5-5. Fifth air inlet. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0043] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] Example

[0047] like Figure 1 As shown, the gradient thermocatalytic cracking, swirl pre-combustion and flue gas recirculation ammonia burner proposed in this invention includes an ammonia ignition and combustion-supporting module 1, a stepped catalyst module 2, a DC swirl composite pre-combustion module 3, an ammonia main combustion stage module 4, and a flue gas recirculation module 5 distributed radially from the inside to the outside.

[0048] The ammonia ignition and combustion-supporting module 1, the stepped catalyst module 2, and the DC swirl composite pre-combustion module 3 adopt a concentric ring design. The ammonia ignition and combustion-supporting module 1 is located in the center, the ammonia main combustion stage module 4 is distributed in a concentric structure outside the stepped catalyst module 2 and the DC swirl composite pre-combustion module 3, and the flue gas recirculation module 5 is located on the outermost layer of the concentric structure.

[0049] The inlet ends of the ammonia ignition and combustion-supporting module 1, the stepped catalyst module 2, the DC swirl composite pre-combustion module 3, the ammonia main combustion stage module 4, and the flue gas recirculation module 5 are arranged sequentially from front to back along the axial direction. The outlet end of the ammonia ignition and combustion-supporting module 1 is located inside the stepped catalyst module 2, the outlet end of the stepped catalyst module 2 is located inside the DC swirl composite pre-combustion module 3, the outlet end of the DC swirl composite pre-combustion module 3 is located inside the ammonia main combustion stage module 4, and the outlet end of the ammonia main combustion stage module 4 is located inside the flue gas recirculation module 5. The outlet end of the ammonia main combustion stage module 4 and the outlet end of the flue gas recirculation module 5 together constitute the burner outlet and are connected to the furnace inlet.

[0050] The ammonia ignition and combustion-supporting module 1 generates a first ammonia flame 1-7, which acts on the stepped catalyst module 2. The ammonia gas introduced through the cracking process is a mixture rich in ammonia, nitrogen, and hydrogen. The DC swirl composite pre-combustion module 3 extracts the cracked gas and ignites it with air to form a second DC standby flame 3-6. The second DC standby flame 3-6 serves as a reliable ignition source, igniting the remaining cracked mixture and forming a second swirl standby flame 3-7 with the assistance of swirling air. The second swirl standby flame 3-7 ignites the ammonia gas ejected from the ammonia main combustion stage module 4, forming a third ammonia flame 4-5 under the action of swirling air.

[0051] The flue gas recirculation module 5 draws high-temperature flue gas through a flue gas recirculation pump and sends it into the flame zone through the outer pipeline of the stepped catalyst module. There, it works together with the heat provided by the first ammonia flame 1-7 to act on the stepped catalyst module 2, and also reduces NO in the flame zone. x The emission concentration is controlled by the air introduced through the fifth air inlet 5-5 on the outer layer of the flue gas recirculation module 5, which cools and protects the burner wall and nozzle.

[0052] In this embodiment, combined with Figure 1 As shown, the ammonia ignition and combustion-supporting module 1 includes a first air inlet 1-1, a low-power sliding arc plasma structure 1-2, a first ammonia inlet 1-3, a second air inlet 1-4, a first swirl vane 1-5, and a second swirl vane 1-6.

[0053] The low-power sliding arc plasma structure 1-2 is composed of a first electrode 1-2-1 and a second electrode 1-2-2. The first electrode 1-2-1 and the second electrode 1-2-2 are connected to a high-voltage power supply and a low-voltage power supply, respectively. The discharge breakdown causes the air introduced through the first air inlet 1-1 to pass through the first swirling blade 1-5 to form a swirling sliding arc. The ammonia gas introduced through the first ammonia gas inlet 1-3 forms the first ammonia gas flame 1-7 under the action of the swirling sliding arc.

[0054] The combustion air introduced through the second air inlet 1-4 is regulated by the second swirl vanes 1-6 to form an outer swirl, ensuring stable combustion of ammonia under wide load conditions.

[0055] Furthermore, the stepped catalyst module 2 includes a second ammonia inlet 2-1, and a platinum-based catalyst 2-2, a ruthenium-based catalyst 2-3, and a nickel-based catalyst 2-4 arranged axially from front to back. The platinum-based catalyst 2-2 is located at the front end of the inlet and is used for low-temperature rapid ignition and primary cracking. The ruthenium-based catalyst 2-3 is located in the middle section and is used for the directional conversion of intermediate products to suppress side reactions. The nickel-based catalyst 2-4 is located in the rear section or periphery and is used for deep cracking in the high-temperature zone and to maintain long-term catalytic activity. Specifically, the layered arrangement of the platinum-based catalyst 2-2, the ruthenium-based catalyst 2-3, and the nickel-based catalyst 2-4 is used to optimize the ratio and position of precious metal and inexpensive metal catalysts.

[0056] Furthermore, the DC swirl composite pre-combustion module 3 includes a standby fuel supply pipe 3-1, a standby air supply pipe 3-2, a standby flame igniter 3-3, a third air inlet 3-4, and a fourth swirl blade 3-5;

[0057] The duty fuel supply pipe 3-1 is connected downstream of the stepped catalyst module 2 and is used to extract the cracked hydrogen-rich mixed gas. The cracked gas is mixed with the air supplied by the duty air supply pipe 3-2 at the duty flame igniter 3-3 and ignited by the ignition needle at the tail end of the duty flame igniter 3-3 to form a stable second DC duty flame 3-6.

[0058] The second DC duty flame 3-6, as a high-intensity and reliable ignition source, further ignites the remaining cracked mixture and interacts with the swirling air introduced through the third air inlet 3-4 and formed by the fourth swirling blade 3-5, together forming a high-power, stable-burning second swirling duty flame 3-7.

[0059] Furthermore, the ammonia main combustion stage module 4 includes a third ammonia inlet 4-1, a fourth air inlet 4-2, an ammonia injection port 4-3, and a fifth swirl vane 4-4;

[0060] The third ammonia inlet 4-1 connects to multiple radially distributed ammonia channels. Ammonia and air are introduced from the third ammonia inlet 4-1 and the fourth air inlet 4-2, respectively. Ammonia is ejected through the ammonia injection port 4-3. Air is introduced through the fourth air inlet 4-2 and forms a swirling flow through the fifth swirl blade 4-4. Ammonia and swirling air mix and form the third ammonia flame 4-5 through the second swirl flame 3-7.

[0061] Finally, the flue gas recirculation module 5 includes a recirculated flue gas outlet 5-1, an air extraction port 5-2, a flue gas recirculation pump 5-3, a recirculated flue gas inlet 5-4, and a fifth air inlet 5-5;

[0062] The downstream exhaust port 5-2 continuously draws in high-temperature flue gas, which, driven by the flue gas circulation pump 5-3, is then transported through a pipeline to the upstream recirculated flue gas inlet 5-4 for reinjection. This provides continuous heat to the stepped catalyst module 2, assisting and enhancing the endothermic cracking reaction of ammonia, thereby generating more reactive hydrogen-rich cracked gas and reducing NO in the flame zone. x The air introduced through the fifth air inlet 5-5 on the outer layer of the flue gas recirculation module 5 cools and protects the burner wall and nozzle, effectively reducing the temperature of the burner wall and internal structure through convective heat transfer.

[0063] The above specific embodiments are merely optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. An ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation, characterized in that, It includes an ammonia ignition and combustion-supporting module (1) distributed radially from the inside out, a stepped catalyst module (2), a DC swirl composite pre-combustion module (3), an ammonia main combustion stage module (4), and a flue gas recirculation module (5). The ammonia ignition and combustion-supporting module (1), the stepped catalyst module (2), and the DC swirl composite pre-combustion module (3) adopt a concentric ring design. The ammonia ignition and combustion-supporting module (1) is located in the center, the ammonia main combustion stage module (4) is distributed in a concentric structure outside the stepped catalyst module (2) and the DC swirl composite pre-combustion module (3), and the flue gas recirculation module (5) is located on the outermost layer of the concentric structure. The inlet ends of the ammonia ignition and combustion-supporting module (1), the stepped catalyst module (2), the DC swirl composite pre-combustion module (3), the ammonia main combustion stage module (4), and the flue gas recirculation module (5) are arranged sequentially from front to back along the axial direction. The outlet end of the ammonia ignition and combustion-supporting module (1) is located inside the stepped catalyst module (2), the outlet end of the stepped catalyst module (2) is located inside the DC swirl composite pre-combustion module (3), the outlet end of the DC swirl composite pre-combustion module (3) is located inside the ammonia main combustion stage module (4), and the outlet end of the ammonia main combustion stage module (4) is located inside the flue gas recirculation module (5). The ammonia ignition and combustion-supporting module (1) generates a first ammonia flame (1-7) which acts on the stepped catalyst module (2). The ammonia gas introduced through the cracking process is a mixture of ammonia, nitrogen, and hydrogen. The DC swirl composite pre-combustion module (3) extracts the cracked gas and ignites it with air to form a second DC standby flame (3-6), which, together with the swirling air, forms a second swirling standby flame (3-7). The second swirling standby flame (3-7) ignites the ammonia gas ejected from the ammonia main combustion stage module (4), and under the action of the swirling air, forms a third ammonia flame (4-5). The flue gas recirculation module (5) extracts high-temperature flue gas and acts on the first ammonia flame (1-7) on the stepped catalyst module (2).

2. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 1, characterized in that, The ammonia ignition and combustion-supporting module (1) includes a first air inlet (1-1), a low-power sliding arc plasma structure (1-2), a first ammonia inlet (1-3), a second air inlet (1-4), a first swirl vane (1-5), and a second swirl vane (1-6). The low-power sliding arc plasma structure (1-2) consists of a first electrode (1-2-1) and a second electrode (1-2-2). The first electrode (1-2-1) and the second electrode (1-2-2) are connected to a high-voltage power supply. The discharge breaks down the swirling air formed by the first swirling blade (1-5) and is used to form the first ammonia flame (1-7) by introducing ammonia gas through the first ammonia gas inlet (1-3). The combustion air introduced through the second air inlet (1-4) is regulated by the second swirl vane (1-6) to form an outer swirl.

3. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 1, characterized in that, The stepped catalyst module (2) includes a second ammonia inlet (2-1), a platinum-based catalyst (2-2), a ruthenium-based catalyst (2-3), and a nickel-based catalyst (2-4) arranged in layers from front to back along the axial direction. The platinum-based catalyst (2-2) is located at the inlet front end and is used for low-temperature rapid ignition and primary pyrolysis; Ruthenium-based catalysts (2-3) are located in the middle section and are used for the directional conversion of intermediate products to suppress side reactions; Nickel-based catalysts (2-4) are located in the later or peripheral stages and are used for deep pyrolysis in the high-temperature zone and to maintain long-term catalytic activity.

4. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 3, characterized in that, The layered arrangement of the platinum-based catalyst (2-2), ruthenium-based catalyst (2-3), and nickel-based catalyst (2-4) is used to optimize the ratio and position of the precious metal and inexpensive metal catalysts.

5. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 1, characterized in that, The DC swirl composite pre-combustion module (3) includes a duty fuel supply pipe (3-1), a duty air supply pipe (3-2), a duty flame igniter (3-3), a third air inlet (3-4), and a fourth swirl blade (3-5). The duty fuel supply pipe (3-1) is connected downstream of the stepped catalyst module (2) and is used to extract the cracked gas and the air from the duty air supply pipe (3-2) to mix and ignite at the duty flame igniter (3-3) to form a second DC duty flame (3-6). Air is introduced through the third air inlet (3-4) and passes through the fourth swirl blade (3-5) to form swirling air. The swirling air mixes with the second direct current duty flame (3-6) to form the second swirling duty flame (3-7).

6. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 1, characterized in that, The ammonia main combustion stage module (4) includes a third ammonia inlet (4-1), a fourth air inlet (4-2), an ammonia injection port (4-3), and a fifth swirl vane (4-4). The third ammonia inlet (4-1) is connected to multiple radially distributed ammonia channels. Ammonia is ejected through the ammonia spray nozzle (4-3). Air is introduced through the fourth air inlet (4-2) and forms a swirling flow through the fifth swirl blade (4-4). Ammonia and swirling air are mixed and form the third ammonia flame (4-5) through the second swirl flame (3-7).

7. The ammonia burner with gradient thermocatalytic cracking, swirl pre-combustion, and flue gas recirculation according to claim 1, characterized in that, The flue gas recirculation module (5) includes a recirculated flue gas outlet (5-1), an air extraction port (5-2), a flue gas recirculation pump (5-3), a recirculated flue gas inlet (5-4), and a fifth air inlet (5-5). The exhaust port (5-2) draws in high-temperature flue gas, which is then driven by the flue gas circulation pump (5-3) and reinjected into the stepped catalyst module (2) through the recirculated flue gas inlet (5-4). The fifth air inlet (5-5) allows air to be introduced for cooling the burner walls and nozzles.

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