An ammonia-only combustor based on coupling of plasma stable combustion and bluff body stable combustion

Abstract

The present application relates to the technical field of ammonia fuel combustion and stable combustion, and particularly relates to a pure ammonia combustor based on plasma stable combustion coupled with bluff body stable combustion. The technical scheme comprises an outer wall surface of the combustor, a combustion chamber formed in the inner part of the outer wall surface of the combustor, and a discharge gas channel, an ammonia gas channel and an air channel arranged along the axial direction of the combustor. The present application prolongs the residence time of fuel at the flame root by means of reverse ammonia injection and forward swirling air butt, improves the plasma uniformity and active component transport efficiency by the first rotating gas ring circumferential gas supply, forms a continuous stable combustion backflow by the second rotating gas ring and bluff body, and combines three bluff body position layouts to adapt to different working conditions, thereby solving the problem that conventional plasma stable combustion cannot be combined with bluff body stable combustion. The present application realizes efficient coupling of sliding arc plasma stable combustion and bluff body stable combustion, utilizes the synergistic complementary relationship between the two, and obtains stable combustion performance gain far exceeding single stable combustion mode.

Description

Technical Field

[0001] This invention relates to the field of ammonia fuel combustion and plasma-assisted combustion technology, and in particular to a pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion. Background Technology

[0002] Ammonia contains no carbon, making it easy to liquefy and transport. It can be directly burned for heating, making it a clean energy carrier with broad application prospects. Compared to conventional hydrocarbon fuels, pure ammonia has a higher ignition temperature, lower reactivity, slower flame propagation speed, and a narrower stable combustion range. When the burner outlet velocity is high, ammonia and air are not fully mixed, and heat loss is significant, pure ammonia flames are prone to problems such as ignition difficulties, flame rise, partial extinction, blow-out, and escape of unburned ammonia, severely restricting the engineering application of pure ammonia fuel.

[0003] When a bluff body is placed in the airflow, the mainstream flow separates at the trailing edge of the bluff body, forming a low-velocity recirculation zone downstream of the bluff body. This recirculation zone transports high-temperature combustion products and active components to the flame root, reducing the axial velocity at the flame root and thus stabilizing the flame. However, when the main fuel, ammonia, is injected directly downstream axially, the ammonia jet penetrates the trailing edge of the bluff body, resulting in insufficient ammonia entering the recirculation zone and making it difficult to fully utilize the flame-stabilizing effect of the bluff body's recirculation zone.

[0004] Sliding arc plasma can provide heat and active components locally, promoting the initial decomposition and ignition of ammonia. However, when the discharge gas is unevenly distributed within the discharge region, the sliding arc discharge is concentrated locally, limiting the energy density of the plasma jet and the yield of active components. Current technologies for enhancing flame stability typically employ only one combustion stabilization method. For instance, in power plant pulverized coal burners, those equipped with plasma ignition no longer include bluff body combustion stabilizers because plasma combustion would disrupt combustion stabilization in the recirculation zone. In short, current technologies cannot couple plasma and bluff body combustion stabilization, thus failing to achieve a synergistic combustion enhancement effect. When the plasma jet formation location does not match the bluff body recirculation zone, the heat and active components generated by the plasma cannot fully reach the flame root, significantly reducing the effectiveness of plasma-assisted combustion.

[0005] In summary, this application proposes a pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion. Summary of the Invention

[0006] The purpose of this invention is to address the problems of difficulty in igniting pure ammonia, slow flame propagation speed, insufficient ammonia gas entering the recirculation zone, and insufficient coupling between plasma and the flame root, and to propose a pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion.

[0007] The technical solution of the present invention: A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion, comprising an outer wall surface of the burner and a combustion chamber formed inside the outer wall surface of the burner, and further comprising: The discharge gas passage, ammonia passage, and air passage are arranged along the burner axis; A ground electrode and a high-voltage electrode, wherein a sliding arc discharge region communicating with the discharge gas channel is formed between the ground electrode and the high-voltage electrode; The first swirling ring is disposed in the discharge gas channel to cause the discharge gas transported through the discharge gas channel to form a swirling flow before entering the sliding arc discharge region and generating a plasma jet toward the combustion chamber. The second cyclone ring is disposed in the air channel to form a cyclone in the air transported through the air channel; A blunt body, disposed in the combustion chamber, is used to cause the swirling air bypassing the blunt body to form a recirculation zone downstream of it; The reverse ammonia injection channel, connected to the ammonia gas channel, is used to inject the main fuel ammonia gas transported by the ammonia gas channel into the inlet of the reflux zone in the upstream direction of the mainstream.

[0008] Optionally, the discharge gas channel and the ammonia channel are set independently of each other, the discharge gas is a mixture of ammonia and air, and the main fuel ammonia is a pure ammonia gas stream.

[0009] Optionally, the outlet of the ammonia channel is connected to the reverse ammonia injection channel, and all the main fuel ammonia is discharged into the combustion chamber through the reverse ammonia injection channel, and the downstream end face of the bluff body is not provided with a direct injection outlet for the main fuel ammonia.

[0010] Optionally, the reverse ammonia injection channel includes a plurality of injection holes arranged at intervals along the circumference of the burner, with the outlet direction of the injection holes facing upstream of the main stream.

[0011] Optionally, the first cyclone ring is provided with a flow guide channel, which is inclined relative to the axis of the burner to enable the discharge gas to obtain tangential velocity and be distributed circumferentially along the sliding arc discharge region; the second cyclone ring is provided with swirl blades to enable the air to obtain axial velocity and tangential velocity.

[0012] Optionally, the trailing edge of the blunt body is located axially downstream of the discharge end of the high-voltage electrode, and the discharge end of the high-voltage electrode is located inside the outlet of the combustion chamber.

[0013] Optionally, the trailing edge of the blunt body is axially flush with the discharge end of the high-voltage electrode.

[0014] Optionally, the trailing edge of the blunt body is located axially upstream of the discharge end of the high-voltage electrode, the discharge end of the high-voltage electrode extends downstream of the trailing edge of the blunt body, and a ceramic swirling ring is provided on the outlet side of the discharge gas channel, through which the discharge gas enters the outlet sliding arc discharge region.

[0015] Optionally, the ceramic cyclone ring is disposed between the high-voltage electrode and the ground electrode. The ceramic cyclone ring is provided with an inclined guide channel communicating with the discharge gas channel. The ceramic cyclone ring is used to electrically insulate and radially position the high-voltage electrode, and to define the discharge gap of the outlet sliding arc discharge region.

[0016] Optionally, it also includes a sliding arc plasma power source, wherein the input terminal of the sliding arc plasma power source is connected to an external power supply, the high-voltage output terminal of the sliding arc plasma power source is connected to the high-voltage electrode, and the low-potential terminal of the sliding arc plasma power source is connected to the ground electrode.

[0017] Compared with the prior art, this application includes at least one of the following beneficial technical effects: All the main fuel ammonia gas is injected through the reverse ammonia injection channel. After colliding with the forward swirling air, it decelerates, turns, and is entrained. The main fuel ammonia gas enters the inlet of the recirculation zone, prolonging the residence time of the main fuel ammonia gas near the flame root, effectively solving the problem that the main fuel ammonia gas is difficult to enter the recirculation zone.

[0018] The first swirling ring distributes the discharge gas circumferentially along the sliding arc discharge region, expanding the contact range between the discharge gas and the sliding arc discharge region, preventing the sliding arc discharge from concentrating in a localized area, and efficiently delivering the heat and active components generated by the plasma to the burner outlet.

[0019] The second cyclone ring and the bluff body together form a bluff body trail recirculation. The recirculated gas carries the high-temperature combustion products and active components back to the bluff body trail edge, providing continuous ignition conditions for the subsequent ammonia and air mixture, thus broadening the stable combustion range of pure ammonia.

[0020] The three bluff body installation positions change the formation position, transport distance, and spatial coupling position of the plasma jet with the recirculation zone, forming three well-defined pure ammonia burners to meet the stable combustion requirements under different operating conditions.

[0021] The ceramic swirling ring in the third structural form integrates the end-swirling of the discharge gas, the insulation of the high-voltage electrode, the positioning of the high-voltage electrode, and the limitation of the sliding arc discharge gap into the same component, which simplifies the burner structure and improves reliability and compactness.

[0022] In summary, this invention extends the fuel residence time at the flame root by counter-current ammonia injection and co-current swirling air counteracting each other; improves plasma uniformity and active component transport efficiency through circumferential air supply from the first swirling ring; and achieves continuous combustion stabilization recirculation through the synergistic interaction between the second swirling ring and the bluff body. Furthermore, it incorporates three bluff body position layouts to adapt to different operating conditions, and integrates insulation, positioning, gap limiting, and end-swirling into a single component using a ceramic swirling ring. This results in a synergistic improvement in both the stability of the pure ammonia flame and the compactness and reliability of the burner structure. This invention achieves highly efficient coupling between sliding arc plasma stabilization and bluff body stabilization, utilizing the synergistic and complementary relationship between the two to obtain combustion stabilization performance gains far exceeding those of a single stabilization method. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the pure ammonia burner of the present invention and the principle of bluff body reflux and stable combustion.

[0024] Figure 2 This is a cross-sectional schematic diagram showing three relative axial positions of the blunt body's trailing edge and the high-voltage electrode discharge end; among them... Figure 2 (a) in the diagram represents the first structural form where the blunt body tail edge is located downstream of the high-voltage electrode discharge end; Figure 2 (b) in the diagram represents the second structural form, where the blunt body tail edge is flush with the discharge end of the high-voltage electrode. Figure 2 (c) in the figure represents the third structural form, where the blunt body tail edge is located upstream of the high-voltage electrode discharge end. Figure 3 A comparison chart of plasma-coupled bluff body flame stabilization performance data; Figure 4 The figures represent combustion states for bluff body-stabilized combustion, plasma-stabilized combustion, and plasma-coupled bluff body-stabilized combustion, respectively.

[0025] Reference numerals: 1. Outer wall of burner; 2. Combustion chamber; 3. Discharge gas channel; 4. Ammonia channel; 5. Air channel; 6. Ground electrode; 7. High voltage electrode; 8. First cyclone ring; 9. Second cyclone ring; 10. Blunt body; 11. Reverse ammonia injection channel; 12. Plasma jet; 13. Recirculation zone; 14. Ceramic cyclone ring. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0027] like Figure 1 As shown, the pure ammonia burner of the present invention adopts a coaxially sleeved tubular structure. The outermost layer is the burner outer wall surface 1, which extends along the axial direction of the burner, and its internal space forms a combustion chamber 2. The combustion chamber 2 is located in the downstream region of the burner and is the main place where the discharge gas, the main fuel ammonia gas, and the combustion air mix and undergo combustion reaction.

[0028] The burner's outer wall surface 1 possesses excellent light transmittance and heat resistance. On the one hand, it can withstand the thermal radiation from the high-temperature flame inside the combustion chamber 2; on the other hand, it facilitates real-time observation and diagnosis of the flame morphology, plasma jet 12 evolution, and flow characteristics of the recirculation zone 13 within the combustion chamber 2 using optical diagnostic methods such as high-speed imaging and laser-induced fluorescence during experiments or operation. This provides convenience for monitoring and optimizing the combustion state. Simultaneously, the burner's outer wall surface 1 isolates the combustion chamber 2 from the external environment, ensuring the stability and safety of the combustion process.

[0029] like Figure 1 and Figure 2 Inside the outer wall 1 of the burner, three gas channels are coaxially arranged from the inside to the outside along the axial direction of the burner: discharge gas channel 3, ammonia gas channel 4, and air channel 5. The three channels are independent and isolated from each other, each undertaking the task of transporting different gas flows, and there is no cross-contamination between them.

[0030] Specifically, the discharge gas channel 3 is located at the innermost part of the burner, with its central axis coinciding with the geometric axis of the burner. It is used to transport the discharge gas, which is a mixture of ammonia and air in a certain proportion. The ammonia channel 4 is fitted around the outer periphery of the discharge gas channel 3 and is used to transport the pure ammonia gas flow as the main fuel. The air channel 5 is fitted around the outer periphery of the ammonia channel 4, that is, located at the outermost part of the three channels, and is used to transport combustion air.

[0031] This coaxial arrangement ensures that the three airflows do not interfere with each other during axial delivery in the burner, maintaining independent flow and pressure control for each. This provides a structural basis for precise proportioning and synergistic effects within combustion chamber 2. Simultaneously, the coaxial arrangement maximizes the use of the burner's radial space, resulting in a compact overall structure.

[0032] In this embodiment, a first swirl ring 8 is disposed inside the discharge gas channel 3, near the upstream of the burner. The first swirl ring 8 has an annular structure, and its outer wall is sealed to the inner wall of the discharge gas channel 3. The first swirl ring 8 has multiple inclined guide channels distributed circumferentially, and these inclined guide channels have a certain angle relative to the axial direction of the burner.

[0033] When the discharge gas, a mixture of ammonia and air, flows downstream along the discharge gas channel 3, it first passes through the inclined guide channel of the first swirling ring 8. Under the guidance of the inclined guide channel, the flow direction of the discharge gas changes from pure axial flow to a rotating flow with both axial and tangential components, thus forming a swirling flow. The swirling discharge gas continues to move downstream along the discharge gas channel 3, and its tangential velocity makes its distribution more uniform across the circumferential cross-section of the channel.

[0034] A ground electrode 6 and a high-voltage electrode 7 are disposed at the downstream end of the discharge gas channel 3. Both the ground electrode 6 and the high-voltage electrode 7 are annular electrodes, which are arranged opposite each other, forming an annular gap between them. This annular gap is the sliding arc discharge region. The sliding arc discharge region is connected to the downstream outlet of the discharge gas channel 3, allowing the swirling discharge gas formed by the first swirling gas ring 8 to smoothly enter this region.

[0035] In this embodiment, the high-voltage electrode 7 is located on the inner side, and the ground electrode 6 is located on the outer side, both arranged coaxially. The high-voltage output terminal of the sliding arc plasma power supply (not shown in the figure) is connected to the high-voltage electrode 7 via a wire, and the low-potential terminal is connected to the ground electrode 6. The input terminal of the sliding arc plasma power supply is connected to an external power supply, such as a 220V DC power supply. Through the boost and frequency conversion circuit inside the power supply, a high-voltage electric field sufficient to break down the discharge gas is established between the high-voltage electrode 7 and the ground electrode 6.

[0036] The first swirling ring 8 ensures a uniform circumferential distribution of the discharge gas within the sliding arc discharge region. This design is significant because uneven gas distribution within the region leads to localized arc discharge, resulting in low energy density, insufficient production of active components, and even arc stagnation or extinction. However, the circumferential gas supply from the first swirling ring 8 continuously renews the gas within the sliding arc discharge region. Driven by the gas flow, the arc rotates and slides circumferentially, forming a large-volume, highly active sliding arc discharge. This significantly improves the energy density of the plasma jet 12 and the generation efficiency of active components (such as NH2, NH, and H radicals).

[0037] In the sliding arc discharge region, the discharge gas is ionized by a high-voltage electric field, undergoing partial ionization and dissociation to form a plasma containing a large number of active particles and high-energy electrons. Carried and propelled by the discharge gas flow, the plasma is ejected from the downstream outlet of the sliding arc discharge region, forming a plasma jet 12 directed towards combustion chamber 2. The plasma jet 12 carries a large amount of heat and chemically active components, transporting them axially to a specific region within combustion chamber 2, providing ignition energy and active centers for the main fuel, ammonia.

[0038] like Figure 1In this embodiment, a second swirl ring 9 is disposed inside the air passage 5, near the upstream of the burner. The second swirl ring 9 is similar to the first swirl ring 8, also being an annular structure, but its specific structural form may differ. In this embodiment, the second swirl ring 9 is provided with multiple swirl blades, which are uniformly distributed circumferentially and installed at a certain angle relative to the axial direction of the burner.

[0039] As the combustion air flows downstream along the air passage 5, it passes through the swirl blades of the second swirl ring 9, gaining axial and tangential velocities to form rotating swirling air. The swirling air continues downstream along the air passage 5, passing through the outer periphery of the blunt body 10. The blunt body 10 is one of the core components of this invention, located within the combustion chamber 2 near the burner outlet. The blunt body 10 has a rotating structure, with its outer periphery forming an annular channel with the inner wall of the burner outer wall 1 for the swirling air to pass through. The trailing edge (i.e., the downstream end face) of the blunt body 10 faces the outlet direction of the combustion chamber 2.

[0040] When the swirling air passes through the outer periphery of the blunt body 10 and crosses its trailing edge, a low-speed recirculation zone 13 is formed downstream of the blunt body 10 due to the sudden expansion of the flow cross section and the flow separation effect at the trailing edge of the blunt body 10. The gas in the recirculation zone 13 returns to the vicinity of the trailing edge of the blunt body 10 in an axial upstream direction, forming a flow pattern similar to "backflow".

[0041] The second cyclone ring 9 and the blunt body 10 together constitute the blunt body wake stabilization system. The existence of the recirculation zone 13 has multiple beneficial effects: First, the low-speed flow in the recirculation zone 13 prolongs the residence time of the combustible mixture near the flame root, which is conducive to complete combustion; Second, the recirculated gas transports the high-temperature combustion products and active components (such as OH, H, O and other free radicals) in the downstream burned area back to the vicinity of the trailing edge of the blunt body 10, providing a continuous ignition heat source and active center for the fresh ammonia and air mixture that has just entered the combustion chamber 2, so that the flame root can remain stable near the inlet of the recirculation zone 13; Third, the shear layer formed between the recirculation zone 13 and the outer high-speed mainstream promotes turbulent mixing and accelerates the mixing process of ammonia and air.

[0042] It should be noted that inside the ammonia passage 4, the main fuel ammonia flows from upstream to downstream along the axial direction of the burner. The downstream end of the ammonia passage 4 extends into the interior of the blunt body 10 and communicates with the reverse ammonia injection passage 11 provided on the blunt body 10.

[0043] The reverse ammonia injection channel 11 includes multiple nozzles, which are arranged circumferentially around the burner on the upstream end face of the blunt body 10 or on the outer peripheral wall of the blunt body 10 near the upstream end face. The outlet direction of the nozzles faces the upstream direction of the mainstream, which is opposite to the overall flow direction of the airflow in the burner (from upstream to downstream).

[0044] The main fuel ammonia gas enters the gas collection chamber (not marked in the figure) inside the blunt body 10 through the ammonia gas channel 4, and then is injected in reverse upstream of the main flow through the nozzle of the reverse ammonia injection channel 11, and is injected into the inlet area of ​​the reflux zone 13.

[0045] It should be noted that in this embodiment, all outlets of the ammonia channel 4 are connected to the reverse ammonia injection channel 11. All the main fuel ammonia is discharged into the combustion chamber 2 through the reverse ammonia injection channel 11, and no axial direct injection outlet is provided on the downstream end face of the blunt body 10. In other words, there is no channel for the main fuel ammonia to be injected directly downstream along the axial direction; all ammonia enters the combustion chamber 2 by reverse injection.

[0046] The counter-currently ejected ammonia fuel gas and the forward-flowing swirling air collide near the inlet of recirculation zone 13. Under the action of the opposing flow, the axial velocity of the ammonia fuel gas first rapidly decreases, and the flow direction is deflected. Subsequently, under the entrainment of the swirling air and recirculation zone 13, it turns downstream and is entrained into the interior of recirculation zone 13. This process allows the ammonia fuel gas to undergo a complete path of deceleration-turning-entrainment-mixing near the flame root, greatly extending its residence time at the flame root, increasing the probability of contact with high-temperature products and active components in recirculation zone 13, and significantly improving the ignition performance and combustion stability of pure ammonia fuel.

[0047] In contrast, if an axial direct injection outlet is set on the downstream end face of the bluff body in the traditional manner, the main fuel ammonia gas will directly penetrate the recirculation zone 13 downstream in the form of a high-speed jet. A large amount of ammonia gas cannot enter the recirculation zone 13, resulting in a significant reduction in the stable combustion effect. The fully reverse ammonia injection design of this invention effectively solves this technical problem.

[0048] It is worth noting that, in order to adapt to different combustion conditions, such as different equivalence ratios, intake flow rates, and outlet flow rates, this invention provides three structural forms for the relative position of the trailing edge of the blunt body 10 and the discharge end of the high-voltage electrode 7. These three forms are achieved by adjusting the axial mounting position of the blunt body 10 and the high-voltage electrode 7, as shown below. Figure 2 (a) Figure 2 (b) and Figure 2 As shown in (c) in the figure.

[0049] (a) First structural form. For example... Figure 2 As shown in (a), in the first structural configuration, the trailing edge of the blunt body 10 is located axially downstream of the discharge end of the high-voltage electrode 7, that is, the discharge end of the high-voltage electrode 7 is located upstream of the trailing edge of the blunt body 10. The discharge end of the high-voltage electrode 7 is located inside the outlet of the combustion chamber 2 and has not yet extended beyond the trailing edge of the blunt body 10.

[0050] In this structural configuration, the sliding arc discharge occurs within the sliding arc discharge region between the high-voltage electrode 7 and the ground electrode 6. The generated plasma jet 12 is ejected from the discharge end of the high-voltage electrode 7 and travels a certain distance axially before reaching the recirculation region 13 downstream of the trailing edge of the blunt body 10. During transport, the plasma jet 12 is entrained and mixed with the surrounding ambient gas, the jet diameter gradually increases, and the temperature field and active component field tend to become uniform.

[0051] Furthermore, the high-voltage electrode 7 is entirely located inside the combustion chamber 2, shielded by the blunt body 10 and the outer wall 1 of the burner. This reduces the direct scouring and thermal radiation effects of the external flame and high-temperature recirculation gas on the high-voltage electrode 7, thus extending its service life and reducing ablation and oxidation of the electrode material. Simultaneously, the longer transport distance allows for more thorough premixing of the plasma jet 12 with the surrounding gas before reaching the recirculation zone 13, facilitating the formation of a larger ignition area within the recirculation zone 13.

[0052] (ii) Second structural form. For example... Figure 2 As shown in (b), in the second structural configuration, the trailing edge of the blunt body 10 is axially flush with the discharge end of the high-voltage electrode 7, meaning they are located in the same axial position. The discharge end of the high-voltage electrode 7 is located exactly in the plane containing the trailing edge of the blunt body 10.

[0053] In this configuration, when the plasma jet 12 is ejected from the discharge end of the high-voltage electrode 7, it immediately enters the inlet region of the recirculation zone 13, and the starting position of the plasma jet 12 is adjacent to the inlet of the recirculation zone 13. The main fuel ammonia gas ejected from the reverse ammonia injection channel 11 meets and mixes with the swirling air and the plasma jet 12 almost simultaneously at the trailing edge of the blunt body 10 and the inlet of the recirculation zone 13.

[0054] It is worth noting that the plasma jet 12 is located closest to the inlet of the recirculation zone 13, ensuring that the heat and active components generated by the plasma reach the flame root via the shortest path and with the least transmission loss, resulting in the highest energy utilization rate. For extreme conditions where ignition is difficult (such as low-temperature start-up or low equivalence ratio), this structural design can maximize the combustion-supporting effect of the plasma.

[0055] (iii) The third structural form. For example... Figure 2 As shown in (c), in the third structural form, the trailing edge of the blunt body 10 is positioned axially upstream of the discharge end of the high-voltage electrode 7, that is, the discharge end of the high-voltage electrode 7 extends downstream of the trailing edge of the blunt body 10. The discharge end of the high-voltage electrode 7 is located outside the trailing edge of the blunt body 10 and extends directly into the interior of the recirculation region 13.

[0056] In this configuration, the discharge end of the high-voltage electrode 7 extends downstream of the blunt body 10, and the sliding arc discharge region moves towards the outlet of the combustion chamber 2. A ceramic swirling ring 14 is also added to the outlet side of the discharge gas channel 3. After the discharge gas forms a swirling flow through the first swirling ring 8 and is transported along the discharge gas channel 3, it must pass through the ceramic swirling ring 14 before entering the sliding arc discharge region.

[0057] The ceramic cyclone ring 14 is made of high-temperature resistant electrically insulating ceramic materials such as alumina ceramics and silicon nitride ceramics, and is disposed between the high-voltage electrode 7 and the ground electrode 6. The ceramic cyclone ring 14 has circumferentially distributed inclined flow channels, which are connected to the downstream outlet of the discharge gas channel 3. After passing through the inclined flow channels of the ceramic cyclone ring 14, the discharge gas undergoes secondary swirling acceleration around the high-voltage electrode 7 and enters the outlet sliding arc discharge region in the form of a rotating jet. The outlet sliding arc discharge region is located inside the recirculation region 13 downstream of the trailing edge of the blunt body 10.

[0058] The ceramic cyclone ring 14 performs multiple functions simultaneously: First, its inclined guide channel performs secondary cyclone distribution of the discharge gas at the end, ensuring that the discharge gas is evenly distributed circumferentially within the outlet sliding arc discharge area; second, the ceramic cyclone ring 14 acts as an insulator between the high-voltage electrode 7 and the ground electrode 6, effectively insulating the high-voltage electrode 7 and preventing unexpected surface discharge or short circuits between the high-voltage electrode 7 and the ground electrode 6; third, the ceramic cyclone ring 14 radially positions the high-voltage electrode 7, ensuring the coaxiality between the high-voltage electrode 7 and the ground electrode 6, thereby precisely defining the discharge gap width of the outlet sliding arc discharge area; finally, as the discharge gas continuously flows from the ceramic cyclone ring 14 towards the combustion chamber 2, a positive pressure airflow barrier is formed, effectively preventing the high-temperature return gas in the return zone 13 from flowing back upstream along the discharge gas channel 3, protecting the upstream discharge gas channel 3 and electrode assembly from high-temperature damage.

[0059] The plasma jet 12 is formed directly within the recirculation zone 13. The heat and active components generated by the plasma are released directly into the flame root region without any transport process, resulting in minimal energy loss and the most direct and intense combustion-supporting effect on the flame root. Simultaneously, the ceramic swirl ring 14 integrates four functions—discharge gas end swirl, high-voltage electrode insulation, high-voltage electrode positioning, and sliding arc discharge gap limitation—into a single component. This reduces the number of parts, simplifies burner assembly and maintenance, and improves structural reliability and compactness.

[0060] It should be noted that the upstream ends of the discharge gas channel 3, ammonia channel 4 and air channel 5 are respectively connected to external gas supply pipelines. Each gas supply pipeline is equipped with a flow regulating valve and a pressure sensor to accurately control the flow rate and pressure of each gas flow.

[0061] Ground electrode 6 and high-voltage electrode 7 are respectively connected to the sliding arc plasma power source via high-voltage wires (not shown in the figure). The high-voltage wires are led out through an insulated and sealed joint on the burner housing to ensure safe isolation of the high-voltage electricity.

[0062] Metal flanges or sealing end caps (not shown in the figure) are respectively provided at the upstream and downstream ends of the burner outer wall 1 to fix the internal channels and electrode assemblies and to seal and isolate the combustion chamber 2 from the external environment. The coaxially fitted channels maintain coaxiality and relative position accuracy through spaced support ribs or positioning rings (not shown in the figure).

[0063] Working Process: During the startup phase, a discharge gas consisting of ammonia and air is first introduced into the discharge gas channel 3. Simultaneously, the sliding arc plasma power supply is activated, establishing a sliding arc discharge between the high-voltage electrode 7 and the ground electrode 6, generating a plasma jet 12. The plasma jet 12 is injected into the combustion chamber 2, preheating the ambient gas within. Subsequently, combustion air is introduced through the air channel 5. The air forms a swirling flow through the second swirling ring 9 and forms a recirculation zone 13 downstream of the blunt body 10. The recirculation zone 13 already contains the heat and active components transported by the plasma jet 12. Next, the main fuel ammonia is introduced through the ammonia channel 4. The main fuel ammonia is injected counter-currently into the inlet of the recirculation zone 13 in the upstream direction of the mainstream through the reverse ammonia injection channel 11. The counter-injected ammonia clashes with the forward swirling air, decelerates, and enters the recirculation zone 13, where it is ignited under the heat and active components provided by the plasma jet 12. After combustion is established, the recirculation zone 13 continuously carries the high-temperature combustion products back to the trailing edge of the blunt body 10, maintaining the stability of the flame root. The plasma jet 12 works continuously as an auxiliary combustion stabilization method, or intermittently according to operating conditions, to maintain combustion stability. When it is necessary to switch operating conditions (such as changing combustion power or equivalence ratio), the appropriate one of the three structural forms can be selected, or parameters such as discharge power and gas flow rate can be adjusted without changing the hardware, so that the burner can adapt to the new operating conditions and ensure that the pure ammonia fuel is always in a stable combustion state.

[0064] To further verify the technical effectiveness of the pure ammonia burner described in this invention, the applicant tested the combustion performance of three stable combustion modes under the same experimental conditions, namely: 1. Only bluff body-stabilized plasma power supply is used for shutdown; 2. Only plasma-stabilized combustion is used to replace the bluff body with a straight pipe of equal diameter, thus avoiding the formation of a reflux zone; 3. The plasma coupling bluff body of the present invention adopts a third structural form, that is, the tail edge of the bluff body is located upstream of the discharge end of the high voltage electrode.

[0065] Experimental results are as follows Figure 3 , Figure 4 As shown. By Figure 3It can be seen that, under the condition of bluff body stabilization only, when the combustion air flow rate is 500 SLM, the ammonia flow rate that can stably burn is only 120 SLM, corresponding to a combustion heat power of 30 kW. At this time, the flame is in a suspended floating state, as... Figure 4 As shown in the corresponding image, the flame root is significantly raised, the brightness is low, and it is constantly shaking, indicating that relying solely on blunt body reflux cannot overcome the inherent defects of pure ammonia flames, such as slow propagation speed and high ignition temperature, and its stabilization capability is very limited.

[0066] Under plasma-stabilized combustion conditions, maintaining an air flow rate of 500 SLM and a plasma discharge power of 5 kW, the ammonia flow rate capable of stable combustion increases to 200 SLM, corresponding to a combustion heat power of 50 kW. The flame morphology is as follows: Figure 4 As shown in the corresponding image, flame adhesion is improved compared to bluff body stabilization, but the overall flame is shorter and the high-temperature zone is limited. Compared to pure bluff body stabilization, ammonia flow rate and combustion heat power are increased by approximately 67%, indicating that the heat and active components provided by the plasma jet promote ignition and stabilization. However, when the ammonia flow rate is further increased, the flame still blows out, indicating that the controllable range of single plasma stabilization has a clear upper limit.

[0067] Under the plasma-coupled bluff body stable combustion conditions of this invention, while maintaining an air flow rate of 500 SLM and a plasma discharge power of 5 kW, the ammonia flow rate capable of stable combustion is significantly increased to 600 SLM, corresponding to a combustion heat power of 150 kW. This ammonia flow rate is 5 times and 3 times that under pure bluff body stable combustion and pure plasma stable combustion conditions, respectively, and the combustion heat power is 5 times and 3 times that of the two conditions, respectively. The flame morphology is as follows: Figure 4 As shown in the corresponding image, the flame is bright and full, the high-temperature zone is significantly expanded, and the flame root is stably attached to the inlet of the recirculation zone near the tail edge of the blunt body, without any lifting or shaking. The combustion state is significantly better than the previous two.

[0068] The above experimental data fully demonstrates that this invention, through the coupling of sliding arc plasma stabilization and bluff body stabilization, increases the stable combustion ammonia flow rate and thermal power to more than three times that of a single stabilization method under the same plasma discharge power and air flow rate, achieving a synergistic effect of plasma-enhanced ignition and bluff body recirculation self-sustaining stabilization. The two stabilization mechanisms are spatially matched and functionally complementary, jointly achieving a significant leap in stabilization performance. This invention achieves efficient coupling between sliding arc plasma stabilization and bluff body stabilization. Experimental results show that, under the same air flow rate and plasma discharge power conditions, the stable combustion ammonia flow rate of this invention is five times that of single bluff body stabilization and three times that of single plasma stabilization, fully verifying the synergistic gain effect between the two stabilization technologies and resulting in a significant improvement in stabilization performance.

[0069] The above specific embodiments are merely several 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. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion, comprising an outer wall surface of the burner (1) and a combustion chamber (2) formed inside the outer wall surface of the burner (1), characterized in that, Also includes: Discharge gas passage (3), ammonia passage (4) and air passage (5) are arranged along the burner axis; Ground electrode (6) and high voltage electrode (7), wherein a sliding arc discharge region is formed between the ground electrode (6) and the high voltage electrode (7) and is connected to the discharge gas channel (3); The first swirling ring (8) is disposed in the discharge gas channel (3) to cause the discharge gas transported through the discharge gas channel (3) to form a swirling flow and enter the sliding arc discharge region, and generate a plasma jet (12) toward the combustion chamber (2). The second cyclone ring (9) is disposed in the air channel (5) to make the air transported through the air channel (5) form a cyclone; A blunt body (10) is disposed in the combustion chamber (2) to cause the swirling air bypassing the blunt body (10) to form a recirculation zone (13) downstream of it. The reverse ammonia injection channel (11) is connected to the ammonia channel (4) and is used to inject the main fuel ammonia gas transported by the ammonia channel (4) into the inlet of the reflux zone (13) in the upstream direction of the main flow.

2. The pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The discharge gas channel (3) and the ammonia channel (4) are set independently of each other. The discharge gas is a mixture of ammonia and air, and the main fuel ammonia is a pure ammonia gas stream.

3. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The outlet of the ammonia channel (4) is connected to the reverse ammonia injection channel (11), and all the main fuel ammonia is discharged into the combustion chamber (2) through the reverse ammonia injection channel (11), and the downstream end face of the blunt body (10) is not provided with a direct injection outlet for the main fuel ammonia.

4. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The reverse ammonia injection channel (11) includes a plurality of injection holes arranged at intervals along the circumference of the burner, with the outlet direction of the injection holes facing upstream of the main stream.

5. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The first cyclone ring (8) is provided with a flow guide channel, which is inclined relative to the axis of the burner to enable the discharge gas to obtain tangential velocity and be distributed circumferentially along the sliding arc discharge region; the second cyclone ring (9) is provided with swirl blades to enable the air to obtain axial velocity and tangential velocity.

6. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The trailing edge of the blunt body (10) is located axially downstream of the discharge end of the high-voltage electrode (7), and the discharge end of the high-voltage electrode (7) is located inside the outlet of the combustion chamber (2).

7. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The trailing edge of the blunt body (10) is axially flush with the discharge end of the high-voltage electrode (7).

8. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, The tail edge of the blunt body (10) is located axially upstream of the discharge end of the high voltage electrode (7), and the discharge end of the high voltage electrode (7) extends downstream of the tail edge of the blunt body (10). A ceramic cyclone ring (14) is provided on the outlet side of the discharge gas channel (3), and the discharge gas enters the outlet sliding arc discharge region through the ceramic cyclone ring (14).

9. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 8, characterized in that, The ceramic cyclone ring (14) is disposed between the high voltage electrode (7) and the ground electrode (6). The ceramic cyclone ring (14) is provided with an inclined guide channel that communicates with the discharge gas channel (3). The ceramic cyclone ring (14) is used to electrically insulate and radially position the high voltage electrode (7) and to limit the discharge gap of the outlet sliding arc discharge region.

10. A pure ammonia burner based on plasma-stabilized combustion coupled with bluff body-stabilized combustion according to claim 1, characterized in that, It also includes a sliding arc plasma power supply, the input end of which is connected to an external power supply, the high voltage output end of which is connected to the high voltage electrode (7), and the low potential end of which is connected to the ground electrode (6).

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