A multi-stage zoned low-nitrogen ammonia gas swirl burner

Abstract

A multi-stage partition low-nitrogen ammonia gas cyclone burner comprises an internal air assembly, an internal air assembly is a passage of a rear thick and a front thin, an internal cyclone air cylinder is placed inside, and an internal air flow forms an axial cyclone after passing through the cyclone air cylinder; an ammonia gas assembly, an end of the ammonia gas assembly forms an annular gap with the internal air assembly, and ammonia gas uniformly flows into a combustion chamber through the annular gap; an external air assembly, the external air assembly is installed at the end of the ammonia gas assembly, external air flows out radially through a circle of small square holes at the end of the external air assembly, and forms a radial cyclone; a center combustion-supporting assembly, the center combustion-supporting assembly is a thin tube installed inside the internal air passage, and fuel is hydrogen; and an outlet combustion-supporting assembly, the outlet combustion-supporting assembly is a ring channel installed at the end of the external air assembly, a plurality of small nozzles are arranged outside the ring channel, and fuel is hydrogen. After ammonia gas is sprayed out from the annular gap, the ammonia gas can be uniformly mixed with internal and external cyclone air, the combustion-supporting assemblies as a whole form a wrapping range of a bottom high-temperature jet flow and a plurality of external high-temperature points, and ammonia gas can be stably combusted in the range.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy engineering technology, and relates to a burner, particularly a multi-stage zoned low-NOx ammonia swirl burner. Background Technology

[0002] Compared to hydrogen, which is difficult to produce and even more difficult to store, ammonia has a mature industrial chain for production, storage, and transportation. Furthermore, its complete combustion produces only nitrogen and water, giving it significant advantages as a fuel. However, ammonia also has characteristics such as difficulty in ignition, slow flame propagation when ignited, and the production of large amounts of nitrogen oxides from incomplete combustion. Therefore, it is necessary to design a burner specifically for ammonia combustion to meet its specific combustion characteristics.

[0003] Most current burners do not use ammonia as fuel. When used to burn ammonia, they generally suffer from the following technical problems: relying on a single ignition source without a combustion-supporting device makes it difficult for ammonia to ignite smoothly, or results in an unstable flame with low rigidity and easy extinguishing; the lack of superior swirl mixing measures leads to uneven mixing of ammonia and air, resulting in localized over-rich and over-lean combustion, creating localized high-temperature points, and further contributing to the large-scale generation of thermal NOx and fuel NOx. Simultaneously, due to incomplete combustion, a significant amount of ammonia is directly emitted into the air without combustion, resulting in low combustion efficiency, environmental pollution, and resource waste. Such a structure is undesirable for ammonia combustion. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a multi-stage zoned low-NOx ammonia swirl burner. By improving the burner structure, the ammonia gas can be stably ignited and burned, the gas mixture can be promoted, and the emission of nitrogen oxides can be further reduced, thus overcoming the deficiencies of the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A multi-stage zoned low-NOx ammonia cyclone burner includes an internal air assembly, an external air assembly, an ammonia assembly, a central combustion aid device, and an outlet combustion aid device.

[0007] The internal air assembly has an internal air channel, and a swirl fan is placed at the end of the internal air channel. The internal air flows into the internal air channel from the internal air inlet pipe, and after passing through the swirl fan, it forms an axial swirl and flows into the combustion chamber.

[0008] The ammonia assembly has an ammonia channel located outside the internal air channel. The ends of the two are combined to form an ammonia outlet annular gap. Ammonia flows into the ammonia channel from the ammonia inlet pipe and then flows axially and evenly into the combustion chamber through the ammonia outlet annular gap. The cross-sectional area of ​​the ammonia outlet annular gap is smaller than the cross-sectional area of ​​the ammonia channel so that the flow velocity of the ammonia flowing into the combustion chamber is greater than the flow velocity of the internal air.

[0009] The external air assembly is installed on the outer side of the rear end of the ammonia assembly. External air flows in from the external air inlet pipe and radially into the combustion chamber through the external air outlet at the end of the external air assembly, thus forming an internal and external air intake method with ammonia entering through the narrow slit in the middle.

[0010] The central combustion-supporting device has a central hydrogen channel, and hydrogen flows into the central hydrogen channel from the central hydrogen inlet and is axially injected into the combustion chamber;

[0011] The combustion-supporting assembly at the outlet has an outlet hydrogen loop channel. Hydrogen flows into the outlet hydrogen loop channel from the outlet hydrogen inlet and is injected into the combustion chamber at an angle to the axial direction.

[0012] In one embodiment, along the airflow direction, the internal air duct is composed of an inverted conical portion and a cylindrical portion connected together, with the cylindrical portion connected to the end of the inverted conical portion. The outer wall of the internal air duct and the inner wall of the ammonia gas duct form the ammonia gas outlet annular seam at the outlet. The swirl fan includes two concentric circular tubes and several curved swirl blades fixed between the concentric circular tubes. The swirl fan is connected to the internal air duct through a groove. By replacing the swirl fan with different blade angles and numbers, the axial swirl of the internal airflow can be controlled.

[0013] In one embodiment, the ammonia inlet pipe is a radial pipe, and a rectifier plate is arranged in the ammonia channel to rectify the ammonia gas whose flow direction is disordered due to radial air intake.

[0014] In one embodiment, an annular baffle with an angle to the axial direction is installed on the outer side of the ammonia outlet annular gap. The diameter of the end of the annular baffle is smaller than the diameter of the front end, so that the ammonia gas flows into the burner at a speed after exiting the ammonia outlet annular gap.

[0015] In one embodiment, the external air outlet is a plurality of small holes arranged circumferentially, the central axis of the small holes having an oblique angle with the radial direction of the burner, so that when the external air flows into the burner, it has a velocity perpendicular to the central axis of the burner. This velocity causes the external air to form an axial vortex, and the direction of the axial vortex is opposite to the direction of the axial vortex of the internal air exiting the vortex duct.

[0016] In one embodiment, the external air outlet is located at the rear end of the ammonia outlet annular seam and the internal air outlet, and the swirling flow direction of the internal air exiting the swirling fan duct is opposite to the swirling flow direction of the external air exiting the external air outlet and the swirling flow direction of the hydrogen in the hydrogen loop at the outlet.

[0017] In one embodiment, the central combustion aid, once ignited, acts as a continuous lamp, forming a high-temperature jet at the center of the bottom of the combustion chamber to provide a thermal atmosphere for the ignition of ammonia. During periods of shutdown, the central combustion aid continues to operate to ensure that any ammonia that was not fully burned during operation is completely combusted, preventing leakage.

[0018] In one embodiment, the end of the central hydrogen channel is connected to a flared central hydrogen nozzle, which has several small outlet holes.

[0019] In one embodiment, the angle β between the injection direction of the hydrogen nozzle at the outlet and the normal to the outer wall of the hydrogen loop at the outlet ranges from 0° to β to 90°.

[0020] In one embodiment, the hydrogen ring at the outlet is flared at the end, and a flame dividing ring is arranged at the end of the hydrogen ring at the outlet. The flame dividing ring is a circular ring and several fan-shaped spokes arranged behind the ammonia ring slot outlet. The flame dividing ring acts as a swirling blunt body, which decelerates the flowing mixed gas and generates local radial swirling flow.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The burner adopts the RQL combustion method of rich combustion followed by lean combustion. Rich combustion, quenching, and lean combustion can all reduce the combustion temperature and reduce the formation of thermal NOx. The overall chemical reaction equivalence ratio is about 1, which reduces the formation of fuel NOx.

[0023] 2. The burner adopts a combination of a central combustion-supporting device and an outlet combustion-supporting component to form a high-temperature jet in the center and a hot atmosphere surrounding multiple high-temperature points at the end, which is beneficial to improving the ignition and combustion stability of ammonia.

[0024] 3. The burner uses various swirling methods, such as the internal and external air, the reverse axial swirling of the combustion gas at the outlet, the radial air intake of the external air, and the radial swirling caused by the velocity difference between the ammonia and the internal air, to ensure that the ammonia and air are fully mixed and burned evenly.

[0025] 4. The burner adopts a replaceable swirl fan 114, which can improve the adaptability of the burner to different operating conditions by replacing the swirl fan with different blade angles and numbers.

[0026] 5. The ammonia gas outlet method of the burner allows the ammonia gas to be injected into the combustion chamber in the most uniform way, and the continuous circumferential air intake method also helps the ammonia gas to be fully mixed with the two streams of air inside and outside, so as to achieve uniform combustion. Attached Figure Description

[0027] Figure 1 This is a three-dimensional perspective view of a quarter section of the present invention.

[0028] Figure 2 for Figure 1 The diagram shows a cross-sectional view of a multi-stage zoned low-NOx ammonia cyclone burner.

[0029] Figure 3 for Figure 2 Sectional view of AA.

[0030] Figure 4 for Figure 1 The diagram shown is a top view of a multi-stage zoned low-NOx ammonia cyclone burner.

[0031] Figure 5 This is a three-dimensional schematic diagram of a vortex fan.

[0032] Figure 6 This is a three-dimensional schematic diagram of the hydrogen nozzle at the outlet.

[0033] Reference numerals: 111, Internal air duct; 112, Internal air inlet pipe; 113, Internal air passage; 114, Swirl air duct; 121, External air duct; 122, External air inlet pipe; 123, External air outlet; 124, Flame dividing ring; 21, Ammonia cylinder; 22, Ammonia inlet pipe; 23, Ammonia passage; 24, Rectifying orifice plate; 25, Ammonia outlet annular seam; 311, Central hydrogen inlet; 312, Central hydrogen passage; 313, Central hydrogen nozzle; 321, Hydrogen inlet at outlet; 322, Hydrogen ring at outlet; 323, Hydrogen nozzle at outlet. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0037] This invention is a multi-stage zoned low-nitrogen ammonia cyclone burner, one end of which is connected to the boiler furnace, and the other end is equipped with an air inlet device and a gas valve group; an ignition device for igniting the gas is installed inside the boiler furnace.

[0038] Structural reference of the swirl burner of the present invention Figures 1 to 6 It includes an internal air assembly, an external air assembly, an ammonia assembly, a central combustion-supporting device, and an outlet combustion-supporting device. For example, any number of these components and devices can be coaxially arranged as needed.

[0039] In this invention, the front end, rear end, or end point are defined by the airflow direction.

[0040] The internal air assembly includes an internal air duct 113, at the end of which a swirl fan 114 is placed. Internal air flows into the internal air duct 113 from the internal air inlet pipe 112, and after passing through the swirl fan 114, it forms an axial swirl and flows into the combustion chamber.

[0041] The ammonia assembly has an ammonia channel 23, which is located outside the internal air channel 113. The two are combined at their ends to form an ammonia outlet annular seam 25. Ammonia flows into the ammonia channel 23 from the ammonia inlet pipe 22, and then flows into the combustion chamber axially and evenly through the ammonia outlet annular seam 25.

[0042] The external air assembly is installed on the outer side of the rear end of the ammonia assembly. External air flows in from the external air inlet pipe 122 and radially into the combustion chamber through the external air outlet 123 at the end of the external air assembly.

[0043] The central combustion aid device has a central hydrogen channel 312, and hydrogen flows into the central hydrogen channel 312 from the central hydrogen inlet 311 and is axially injected into the combustion chamber.

[0044] The combustion aid assembly at the outlet has an outlet hydrogen loop 322. Hydrogen flows into the outlet hydrogen loop 322 from the outlet hydrogen inlet 321 and is injected into the combustion chamber at an angle to the axial direction.

[0045] Air enters the burner from both the inner and outer sections, while ammonia gas flows into the burner through the ammonia outlet annular slit 23 between the two air streams. This allows the ammonia gas to be fully agitated by the two swirling air streams, rapidly forming a homogeneous mixture. This helps avoid incomplete combustion caused by localized rich combustion and high NOx formation caused by localized lean combustion. Furthermore, this invention achieves thorough mixing of ammonia and air through the axial swirling of the internal air and the radial swirling of the external air.

[0046] In one hardware structure of the present invention, the internal air assembly includes an internal air duct 111 and a swirl air duct 114, the internal air channel 113 is the internal space of the internal air duct 111, and the internal air inlet pipe 112 is the axial inlet of the internal air duct 111.

[0047] The ammonia gas assembly includes an ammonia gas cylinder 21 and a flow rectifier plate 24. The ammonia gas cylinder 21 is located outside the internal ventilation duct 111. The ammonia gas channel 23 is a channel formed between the inner wall of the ammonia gas cylinder 21 and the outer wall of the internal ventilation duct 111. The flow rectifier plate 24 connects the inner wall of the ammonia gas cylinder 21 and the outer wall of the internal ventilation duct 111 and is perpendicular to the axial direction of the channel. The ammonia gas inlet pipe 22 is the radial inlet at the front end of the ammonia gas channel 23, and the ammonia gas outlet annular seam 25 is the end portion between the inner wall of the ammonia gas cylinder 21 and the outer wall of the internal ventilation duct 111.

[0048] The external air assembly includes an external air duct 121 and a flame dividing ring 124. The external air duct 121 is located outside the ammonia gas cylinder 21, and the flame dividing ring 124 is located at the flame outlet of the combustion chamber. The external air inlet pipe 122 is the radial inlet at the front end of the external air duct 121, and the external air outlet 123 is the radial outlet at the end of the external air duct 121.

[0049] The central combustion aid device includes an axial tube and a central hydrogen nozzle 313. The axial tube is located in the internal air duct 111. The interior of the axial tube is the central hydrogen channel 312, and the central hydrogen inlet is the axial inlet at the front end of the axial tube.

[0050] The combustion-supporting assembly at the outlet includes an annular cylinder and several outlet hydrogen nozzles 323. The interior of the annular cylinder is an outlet hydrogen loop 322. The outlet hydrogen inlet 321 can be an inlet at any position on the annular cylinder, preferably an even number of symmetrical inlets. Each outlet hydrogen nozzle 323 faces the outlet flame of the combustion chamber.

[0051] For example, the internal air duct 111 is a goblet shape with a narrow inlet and a wide outlet, that is, it is composed of an inverted conical part and a cylindrical part connected together, with the cylindrical part connected to the end of the inverted conical part. This shape is also the shape of the internal air passage 113. This design is to cooperate with the ammonia gas cylinder 21 to form the ammonia gas outlet annular slit 25 at the outlet. Specifically, the outer wall of the internal air passage 113 and the inner wall of the ammonia gas passage 23 form the ammonia gas outlet annular slit 25 at the outlet. This structure of the ammonia gas outlet annular slit 25 allows the ammonia gas to be sprayed out of the ammonia gas cylinder 21 more evenly. At the same time, because the outlet cross-sectional area of ​​the ammonia gas outlet annular slit 25 is small, the flow velocity of the ammonia gas increases when it passes through the ammonia gas outlet annular slit 25. The higher flow velocity of the ammonia gas and the lower flow velocity of the internal air create a pressure difference, which promotes the thorough mixing of the ammonia gas with the axially swirling internal air. This helps to avoid the generation of local high-temperature zones and reduce the formation of thermal NOx.

[0052] In one embodiment, the swirl duct 114 is installed at the end of the internal duct channel 113. For example, the swirl duct 114 mainly consists of two concentric cylinders and curved swirl blades fixedly installed between the two concentric cylinders. These curved swirl blades are curved blades with a certain curvature and a small arc. This design helps to enhance the swirl effect without increasing air intake resistance, resulting in a more uniform mixing of ammonia and air.

[0053] For details, please refer to [link / reference]. Figure 5 In one embodiment, the swirl fan duct comprises 24 curved swirl blades, rotating counterclockwise to generate counterclockwise axial swirling airflow, opposite to the external airflow and the combustion-supporting gas flow at the outlet. This further promotes the mixing of the gas mixture, resulting in more uniform and complete combustion. Because the blades themselves are curved, the air, when blocked by the blades and generating axial velocity, can move close to the blade surface, reducing intake resistance and ensuring that the internal airflow has a sufficiently large axial swirling intensity to entrain the ammonia gas flowing out from the ammonia outlet annular slit 25. Additionally, the outer wall of the swirl fan duct 114 has several strip-shaped protrusions arranged circumferentially, which can be matched one-to-one with several strip-shaped grooves at the end of the inner fan duct 11 for circumferential fixation of the swirl fan duct 114. The inner fan duct 11 has a flat base in the middle, and the swirl fan duct 114 can be mounted against the base for axial fixation. In engineering, the grooved fixing feature facilitates easy disassembly and installation, allowing for the production of swirl tubes with different blade angles and numbers to adapt to varying requirements for internal airflow intensity under different operating conditions. In other words, by replacing the swirl tubes 114 with different blade angles and numbers, the axial swirl of the internal airflow can be controlled. This design improves the burner's adaptability to different combustion conditions and requirements.

[0054] In one embodiment, the ammonia gas cylinder 21 is concentrically arranged on the outside of the inner air duct 111 and is a cylindrical shape. The ammonia gas inlet pipe 22 is a radial pipe located at the bottom end of the ammonia gas cylinder 21. Specifically, it adopts four circular pipes arranged symmetrically on four sides. The purpose of this design is to ensure that the intake and flow rate of ammonia gas are uniform in the circumference by using ammonia gas intake from four sides, so as to maintain good flame symmetry, further enhance flame stability, ensure high flame rigidity, and help prevent flame surface deviation from interfering with the flame on the furnace or burner wall.

[0055] A rectifier orifice plate 24 is disposed in the ammonia gas channel 23, located before the ammonia gas outlet annular seam 25; only one orifice plate is required. The rectifier orifice plate 24 has a central hole and can be installed on the outer wall of the internal air duct 21 via a flange. This design rectifies the turbulent flow of ammonia gas caused by radial air intake, ensuring a stable flow of ammonia gas into the combustion chamber. This directs the overall ammonia gas flow axially and further improves the circumferential uniformity of the ammonia gas flow, ensuring uniform mixing with air upon exiting the gas, thus improving flame symmetry and flame rigidity. Furthermore, because the internal air duct 111 is goblet-shaped with a narrow inlet and a wide outlet, the internal airflow exhibits a distribution of high velocity in the inner ring and low velocity in the outer ring at the outlet. Therefore, at the end of the ammonia cylinder 21, an annular baffle is installed on the outside of the ammonia outlet annular slit 25 at a 30° angle to the central axis of the burner. This baffle changes the direction of the ammonia flow uniformly out of the ammonia outlet annular slit 25, giving the ammonia a velocity that flows into the burner after exiting the ammonia outlet annular slit 25. This allows the ammonia to mix more strongly with the swirling air in the internal airflow, further promoting uniform mixing of the ammonia and the internal airflow. Simultaneously, due to the small cross-sectional area of ​​the annular slit outlet, the ammonia flow velocity increases. The higher velocity ammonia and the lower velocity internal airflow create a pressure difference, promoting thorough mixing of the ammonia with the axially swirling internal airflow. This helps avoid the formation of localized high-temperature zones and reduces the generation of thermal NOx.

[0056] In one embodiment, the external air assembly is disposed at the rear end of the ammonia cylinder 21 and is installed by fitting it against the annular baffle at the aforementioned ammonia outlet annular seam 25. External air flows in through two symmetrically distributed external air inlet pipes 122 and then flows out radially through the external air outlet 123. For example, the external air inlet pipes 122 are symmetrically distributed circular pipes; this arrangement facilitates the uniformity of external air intake on both sides and improves flame symmetry. For example, the external air outlet 123 is a plurality of small square holes arranged in a circumferential array at the end of the external air cylinder 121.

[0057] For details, please refer to [link / reference]. Figure 2 and Figure 3In one embodiment, external air flows radially into the burner through several small square holes, forming an airflow from the outside in. This airflow, carrying high-velocity ammonia gas ejected from the ammonia annular outlet 25, is drawn into the internal swirling airflow, which flows counter-clockwise through the swirling fan duct 114, and then purges towards the center of the burner. This method of air intake from both the inside and outside, with air entering through a narrow slit in the middle, allows for thorough mixing of the gas mixture, forming a uniform diffusion flame. Under this purging action, the ammonia gas is further blown towards the center of the burner, mixing with the internal airflow. The overall effect of the simultaneous action of the internal and external airflows is that the ammonia gas is mixed by both streams of air simultaneously, continuously blown from the ammonia annular outlet 25 towards the center of the burner, mixing with the internal airflow with higher swirling intensity at the center, and achieving a basically uniform mixture with the air when ejected from the burner. Furthermore, the central axis of the small square holes in the external air outlet 123 is deviated at a small angle from the radial direction of the burner, giving the external airflow a certain velocity perpendicular to the central axis of the burner as it flows into the burner. This velocity allows the external airflow to have a certain axial swirling effect. The swirling direction is clockwise, opposite to the internal air swirling direction. This design allows the ammonia gas sandwiched between the two air streams to be further agitated, promoting a uniform mixing of the two.

[0058] In one embodiment, a flame dividing ring 124 is arranged at the burner outlet. Specifically, the flame dividing ring 124 is a circular ring with several fan-shaped spokes arranged behind the ammonia annular outlet 25. This design divides the flame surface into multiple smaller, independent flame surfaces, increasing the contact area between the flame surface and the air inside the boiler furnace, which helps to reduce the flame temperature and ensure complete fuel combustion. Simultaneously, this design acts as a swirling blunt body, slowing down the mixed gas flowing through the flame dividing ring and generating localized radial swirling flow, enhancing the thorough mixing of the gas mixture, which is beneficial for the complete combustion of ammonia and also avoids the formation of localized high-temperature zones. See details for further information. Figure 5 .

[0059] Because the external air outlet 123 is positioned higher than the ammonia outlet annular gap 25 and the internal air outlet, the combustion of ammonia and air achieves RQLRich-Burn / Quick-Quench / Lean-Burn combustion. At the ammonia outlet annular gap 25, the ammonia is too rich and the air is insufficient, resulting in a low combustion temperature and a reduction in both fuel-type NOx and thermal NOx. When the ammonia flows to the external air outlet 123, the lower-temperature external air inflow causes a rapid drop in the mixture temperature, simultaneously reducing the ammonia concentration and lowering the combustion temperature, thus reducing the formation of thermal NOx. Overall, the total amount of external and internal air is chemically equivalent to the amount of ammonia in a 1:1 ratio, resulting in a relatively small amount of fuel-type NOx generated from the combustion of ammonia itself. Therefore, the overall NOx formation in the combustion products is lower than in conventional combustion.

[0060] Because ammonia is difficult to ignite and has unstable combustion, this invention uses a method of synchronously assisting combustion with a central combustion-supporting device and an outlet combustion-supporting device.

[0061] In one embodiment, the central combustion aid device is arranged inside the internal air duct 111 and the swirl air duct 113, and is a long, thin cylindrical tube. The combustion aid is hydrogen. Hydrogen has strong combustion stability and is easily ignited. After the central combustion aid device is ignited, it can act as a continuous flame, forming a high-temperature jet at the center of the bottom of the combustion chamber to provide a hot atmosphere for the ignition of ammonia. Simultaneously, the central combustion aid device continues to operate during boiler shutdown, ensuring complete combustion of any unburned ammonia during boiler operation and preventing leakage. For example, the central hydrogen channel 312, the internal air duct 113, and the ammonia channel 23 are coaxially arranged from the inside out. For example, the central hydrogen nozzle 313 is flared, with a shower-like end. The shower-like nozzle has numerous small outlet holes, allowing hydrogen to form a large-area, multi-directional combustion flame after being ejected from the multi-hole nozzle. This creates a large-area, high-temperature jet at the bottom, helping the ammonia ignite smoothly, expanding the bottom hot atmosphere coverage area, and enhancing the combustion aid effect.

[0062] In one embodiment, the combustion-supporting device at the outlet is arranged at the end of the external ventilation duct 121. The end of the hydrogen ring 322 at the outlet is flared, forming an isosceles right-angled triangular ring. Hydrogen enters the ring through the hydrogen inlets 321 symmetrically arranged at both ends and is ejected by a plurality of hydrogen nozzles 323 arranged circumferentially on the outer wall of the hydrogen ring 322 at the outlet. The aforementioned flame dividing ring 124 is arranged at the end of the hydrogen ring 322 at the outlet. The advantage of this design is that it can arrange more hydrogen outlets with fewer hydrogen inlets, forming a relatively uniform high-temperature combustion point. The hydrogen nozzles 323 at the outlet are a plurality of small nozzles arranged circumferentially on the wall of the hydrogen ring 322 at the outlet. For example, the angle β between the spray direction (central axis) of the hydrogen nozzles 323 at the outlet and the normal to the outer wall of the hydrogen ring 322 at the outlet is in the range of 0° < β < 90°, preferably 45°. This design allows the hydrogen jet to generate a certain axial swirling flow, and this swirling flow is clockwise, opposite to the internal air swirling flow, which enables a more uniform mixing of ammonia and air. The hydrogen nozzle 323 at the outlet has several small holes circumferentially surrounding an ellipsoidal nozzle. This design makes the hydrogen jet scatter, which helps to expand the combustion-supporting range. For details, please refer to... Figure 6 .

[0063] Overall, the central combustion-supporting device and the outlet combustion-supporting device form a high-temperature jet at the bottom center, along with a high-temperature range of multiple high-temperature points at the top periphery, comprehensively enveloping the ammonia / air mixture inside the burner. This high-temperature envelopment provides a thermal atmosphere for the ignition and stable combustion of hydrogen, which is beneficial for the continuous and stable ignition and combustion of ammonia. Furthermore, the combustion-supporting device described in this invention continuously burns as a perpetual lamp, remaining operational even when the boiler is not in use. This ensures complete combustion of any unburned residual exhaust gas in the burner and boiler, preventing leakage into the air and causing pollution.

[0064] Since ammonia contains hydrogen atoms, this invention can utilize the catalytic decomposition of ammonia to produce hydrogen, which serves as the combustion-supporting hydrogen source. This means the combustion-supporting hydrogen can be directly prepared from ammonia, thus achieving a single raw material. Currently, the technology for producing hydrogen from ammonia through decomposition is mature. Under the action of a nickel-based catalyst, heating liquid ammonia to approximately 800–850°C can achieve ammonia decomposition to produce hydrogen, yielding a hydrogen-nitrogen mixture containing 75% hydrogen and 25% nitrogen. Pure hydrogen can then be obtained by separating the hydrogen and nitrogen through a low-temperature, pressurized liquefaction method. The decomposition reaction pressure can be at atmospheric pressure, and the liquid ammonia has very high purity, containing only small amounts of inert gases and moisture, with trace amounts of oxygen. Therefore, no side reactions can occur during ammonia decomposition. Thus, this invention can achieve combustion entirely using ammonia as a raw material, without requiring a separate hydrogen supply.

[0065] In one specific installation method, the central combustion aid device is installed in close contact with the swirling fan 114 through the flared section of the central hydrogen nozzle 313; the swirling fan 114 is installed by fitting with several grooves at the end of the internal fan duct and the base; the internal fan duct, the rectifier plate, and the ammonia cylinder are all installed by flanges; the external air assembly and the ammonia cylinder, and the external air assembly and the combustion aid device at the outlet are all installed by welding at the fitting points.

[0066] The embodiments described in this specific implementation are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made according to the structure, shape, and principle of the invention should be covered within the scope of protection of the present invention.

Claims

1. A multi-stage zoned low-NOx ammonia cyclone burner, characterized in that, It includes an internal air assembly, an external air assembly, an ammonia assembly, a central combustion-supporting device, and an outlet combustion-supporting device; The internal air assembly has an internal air passage (113), and a swirl fan (114) is placed at the end of the internal air passage (113). The internal air flows into the internal air passage (113) from the internal air inlet pipe (112), and after passing through the swirl fan (114), it forms an axial swirl and flows into the combustion chamber. The ammonia assembly has an ammonia channel (23) located outside the internal air channel (113). The two are combined at their ends to form an ammonia outlet annular seam (25). Ammonia flows into the ammonia channel (23) from the ammonia inlet pipe (22) and then flows into the combustion chamber axially and uniformly through the ammonia outlet annular seam (25). The cross-sectional area of ​​the ammonia outlet annular seam (25) is smaller than that of the ammonia channel (23) so that the flow velocity of the ammonia flowing into the combustion chamber is greater than that of the internal air. The external air assembly is installed on the outer side of the rear end of the ammonia assembly. External air flows in from the external air inlet pipe (122) and flows radially into the combustion chamber through the external air outlet (123) at the end of the external air assembly, thereby forming an internal and external air intake and ammonia gas intake through the middle slit. The central combustion aid device has a central hydrogen channel (312), and hydrogen flows into the central hydrogen channel (312) from the central hydrogen inlet (311) and is axially injected into the combustion chamber; The combustion aid device at the outlet has an outlet hydrogen loop (322), and hydrogen flows from the outlet hydrogen inlet (321) into the outlet hydrogen nozzle (323) and is injected into the combustion chamber at an angle to the axial direction.

2. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, Along the airflow direction, the internal air passage (113) is composed of an inverted conical part and a cylindrical part connected together. The cylindrical part is connected to the end of the inverted conical part. The outer wall of the internal air passage (113) and the inner wall of the ammonia passage (23) form the ammonia outlet annular seam (25) at the outlet. The swirl fan (114) includes two concentric circular tubes and several curved swirl blades fixed between the concentric circular tubes. The swirl fan (114) and the internal air passage (113) are connected by a groove. The axial swirl of the internal air can be controlled by changing the swirl fan (114) with different blade angles and numbers.

3. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, The ammonia inlet pipe (22) is a radial pipe, and a rectifier plate (24) is arranged in the ammonia channel (23) to rectify the ammonia gas whose flow direction is disordered due to radial air intake.

4. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, An annular baffle with an angle to the axial direction is installed on the outside of the ammonia outlet annular seam (25). The diameter of the end of the annular baffle is smaller than the diameter of the front end, so that the ammonia gas flows into the burner at a speed after exiting the ammonia outlet annular seam (25).

5. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, The external air outlet (123) consists of several small holes arranged circumferentially. The central axis of the small holes is at an angle to the radial direction of the burner, so that when the external air flows into the burner, it has a speed perpendicular to the central axis of the burner. This speed causes the external air to form an axial vortex, and the direction of the axial vortex is opposite to the direction of the axial vortex of the internal air in the vortex duct (114).

6. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1 or 5, characterized in that, The external air outlet (123) is located at the rear end of the ammonia outlet annular seam (25) and the internal air outlet. The swirling flow direction of the internal air exiting the swirling wind duct (114) is opposite to the swirling flow direction of the external air exiting the external air outlet (123) and the swirling flow direction of the hydrogen exiting the hydrogen nozzle (323) at the outlet.

7. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, Once ignited, the central combustion-supporting device acts as a continuous lamp, forming a high-temperature jet at the center of the bottom of the combustion chamber to provide a thermal atmosphere for the ignition of ammonia. During periods of shutdown, the central combustion-supporting device continues to operate to ensure that any ammonia that was not fully burned during operation is completely combusted, preventing leakage.

8. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, The end of the central hydrogen channel (312) is connected to a flared central hydrogen nozzle (313), and the central hydrogen nozzle (313) is provided with several small outlet holes.

9. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, The angle β between the injection direction of the hydrogen nozzle (323) at the outlet and the normal to the outer wall of the hydrogen ring channel (322) at the outlet is in the range of: 0° < β < 90°.

10. The multi-stage zoned low-NOx ammonia cyclone burner according to claim 1, characterized in that, The hydrogen ring channel (322) at the outlet is flared at the end, and a flame dividing ring (124) is arranged at the end of the hydrogen ring channel (322) at the outlet. The flame dividing ring (124) is a circular ring and several fan-shaped spokes arranged behind the ammonia outlet ring seam (25). The flame dividing ring (124) acts as a swirling blunt body, which decelerates the flowing mixed gas and generates local radial swirling flow.

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