A fuel gas ammonia-doped low-nitrogen combustor based on ammonia in-situ cracking
By designing a fuel gas ammonia-blended low-NOx burner with in-situ ammonia pyrolysis, the in-situ pyrolysis and mixing of ammonia fuel is achieved by using a high-temperature entrainment reflux zone and annular air curtain to separate the ammonia fuel. This solves the problems of unstable combustion of ammonia and combustible gases and high NOx emissions, and improves combustion efficiency and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN UNIV OF TECH
- Filing Date
- 2025-09-11
- Publication Date
- 2026-08-04
AI Technical Summary
Existing burners are unable to effectively mix and optimize the combustion process of ammonia and combustible gases, resulting in unstable combustion, reduced efficiency, and increased NOx emissions, which cannot meet the needs of practical applications.
A fuel gas ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis is designed. An adjustable ammonia fuel pipe is set at the center, and a circulating flue gas pipe, a fuel gas pipe, an inner swirl combustion air pipe and an outer swirl combustion air pipe are sequentially set around it to form a high-temperature entrainment reflux zone. An annular air curtain is used to separate the unpyrolyzed ammonia fuel, realizing the in-situ pyrolysis of ammonia fuel, and mixing hydrogen and fuel gas in the high-temperature entrainment reflux zone.
It achieves thorough mixing of ammonia fuel and fuel gas, improves combustion efficiency, reduces NOx formation, adapts to a wide range of ammonia blending ratios and all operating conditions, and ensures combustion stability and efficiency.
Smart Images
Figure CN224593283U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of clean combustion technology, specifically to a fuel gas ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis. Background Technology
[0002] To reduce carbon emissions from coal combustion, a common approach in existing technologies is to replace or partially replace traditional fossil fuels with new renewable resources. Ammonia (NH3), as a carbon-free hydrogen carrier, has advantages such as mature technologies for its preparation, storage, and transportation, and is considered a highly promising future fuel.
[0003] However, ammonia combustion suffers from problems such as slow flame velocity, narrow flammability range, difficulty in ignition, low combustion temperature, and the tendency to produce high concentrations of nitrogen oxides (NOx) under certain conditions. Directly co-firing ammonia in existing natural gas burners often results in unstable combustion, decreased efficiency, flameout, backfire, and a sharp increase in NOx emissions. Furthermore, existing burner designs are typically designed for single fuels or fuels with similar properties, failing to simultaneously optimize the mixing and combustion process of combustible gases and ammonia—two fuels with vastly different physicochemical properties. This means that the co-firing of these two fuels cannot fully meet the demands of practical applications. Utility Model Content
[0004] To address one or more of the aforementioned deficiencies or improvement needs in the existing technology, this utility model provides a fuel gas ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis, which can achieve the co-combustion of ammonia fuel and fuel gas, ensuring the combustion effect of the fuel gas while reducing NO. x The generation of .
[0005] To achieve the above objectives, this utility model provides a fuel gas ammonia-blended low-NOx burner based on in-situ ammonia cracking, characterized in that it includes an adjustable ammonia fuel pipe located at the center, and a circulating flue gas pipe, a fuel gas pipe, an inner swirling combustion air pipe and an outer swirling combustion air pipe sequentially arranged around the adjustable ammonia fuel pipe, and a circulating flue gas passage, a fuel gas passage, an inner swirling combustion air passage and an outer swirling combustion air passage are formed sequentially between adjacent pipes from the inside to the outside; The inner swirling combustion-supporting gas channel and the outer swirling combustion-supporting gas channel are used to introduce combustion-supporting gas into the combustion chamber and form a high-temperature entrainment and recirculation zone in the combustion chamber. The outlet end of the adjustable ammonia fuel pipe extends into the high-temperature entrainment recirculation zone, and its tail end away from the combustion chamber is connected to a drive mechanism, which allows the adjustable ammonia fuel pipe to move back and forth axially under the drive of the drive mechanism to adjust the injection position of ammonia fuel in the combustion chamber. The circulating flue gas channel is an annular cavity used to inject high-speed, low-oxygen flue gas into the combustion chamber and form an annular air curtain around the ammonia fuel injected into the combustion chamber to separate the unpyrolyzed ammonia fuel from the high-temperature entrainment recirculation zone.
[0006] The ammonia fuel is introduced into the combustion chamber through an adjustable ammonia fuel pipe that extends into the high-temperature entrainment recirculation zone. The ammonia fuel is separated from the high-temperature entrainment recirculation zone by an annular air curtain formed by the circulating flue gas, so that the ammonia fuel can be deeply decomposed into hydrogen and nitrogen when passing through the high-temperature entrainment recirculation zone. At the tail end of the high-temperature entrainment recirculation zone, the decomposed ammonia fuel is entrained into the fuel gas jet region by the swirling effect.
[0007] As a further improvement of this utility model, the adjustable ammonia fuel pipe has a multi-layer channel structure, which includes a central conveying channel and at least one annular conveying channel formed outside the central conveying channel.
[0008] As a further improvement of this utility model, the adjustable ammonia fuel pipe includes an inner ammonia fuel pipe and an outer ammonia fuel pipe arranged coaxially. The inner ammonia fuel pipe and the outer ammonia fuel pipe can perform synchronous reciprocating motion in the axial direction under the drive mechanism; and the injection flow rate and injection speed of ammonia fuel in the inner ammonia fuel pipe and the outer ammonia fuel pipe are adjustable.
[0009] As a further improvement of this utility model, a three-way flow valve is provided on the ammonia fuel conveying pipeline; the inlet of the three-way flow valve is connected to the ammonia fuel conveying pipeline, and the two outlets of the three-way flow valve are respectively connected to the inner ammonia fuel pipe and the outer ammonia fuel pipe. and / or The ratio of the cross-sectional area of the inner cavity of the inner ammonia fuel pipe to the cross-sectional area of the annular cavity formed between the outer ammonia fuel pipe and the inner ammonia fuel pipe is 1:1 to 4:1. and / or The flow velocity of ammonia fuel in the inner ammonia fuel pipe is not less than the flow velocity of the high-speed low-oxygen flue gas, and the flow velocity of the high-speed low-oxygen flue gas is 1.2 to 3 times the flow velocity in the outer ammonia fuel pipe.
[0010] As a further improvement of this utility model, it also includes an end expansion type gradient structure provided at one end of each pipe other than the adjustable ammonia fuel pipe that connects to the combustion chamber. The end-expansion gradient structure consists of a variable-diameter inner cavity formed on at least part of the inner circumferential wall of the pipe end and / or a variable-diameter end on at least part of the outer circumference of the pipe end; the inner diameter of the variable-diameter inner cavity increases sequentially from the middle of the pipe to the end; the outer diameter of the variable-diameter end increases sequentially from the middle of the pipe to the end.
[0011] As a further improvement of this utility model, the diameter-changing inner cavity and / or the diameter-changing end have a diameter-changing angle of 0° to 45° relative to the pipe axis.
[0012] As a further improvement of this utility model, the inner swirling combustion-supporting gas channel and the outer swirling combustion-supporting gas channel are provided with swirlers to introduce combustion-supporting air into the combustion chamber in a swirling form.
[0013] As a further improvement of this utility model, the cyclone is an axial blade cyclone with adjustable blade inclination angle, which is used to achieve independent control of the backflow intensity and mixing intensity.
[0014] As a further improvement of this utility model, the driving mechanism is an electric push rod, a precision lead screw and nut mechanism driven by a servo motor, or a hydraulic cylinder; and / or The fuel gas introduced into the fuel gas pipe is natural gas.
[0015] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.
[0016] In summary, the beneficial effects of the above-described technical solutions conceived by this utility model compared with the prior art include: This invention relates to a fuel gas ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis. It includes a centrally located adjustable ammonia fuel pipe and, sequentially surrounding the adjustable ammonia fuel pipe, a circulating flue gas pipe, a fuel gas pipe, an inner swirl combustion-supporting air pipe, and an outer swirl combustion-supporting air pipe. The arrangement of these pipes enables the corresponding delivery of ammonia fuel, low-oxygen flue gas, fuel gas, and the inner and outer swirl combustion-supporting gases. Through the adjustable ammonia fuel pipe outlet position and the design of the annular air curtain, the high-temperature environment of the high-temperature entrainment recirculation zone can be effectively utilized to achieve in-situ pyrolysis of the ammonia fuel, thereby achieving reliable mixing of fuel gas and pyrolyzed hydrogen. This improves the combustion efficiency of the fuel gas while reducing NOx. x Emissions. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is an axial cross-sectional view of the fuel gas ammonia-blended low-NOx burner based on in-situ ammonia cracking in this embodiment of the present invention; Figure 2 This is a schematic diagram showing the combustion effect (speed) corresponding to different ammonia tube positions in the burner in this embodiment of the present invention; Figure 3 This is a schematic diagram of the combustion effect (temperature) corresponding to different ammonia pipe positions in the burner in this embodiment of the present invention; Figure 4 This invention relates to the NO emissions at the burner outlet under different ammonia fuel pipe extension lengths and ammonia distribution ratios in the inner and outer ammonia fuel channels in this embodiment of the invention. In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Adjustable ammonia fuel pipe; 101. Inner ammonia fuel pipe; 102. Outer ammonia fuel pipe; 2. Circulating flue gas pipe; 3. Fuel gas pipe; 4. Inner swirl combustion air pipe; 5. Outer swirl combustion air pipe; 6. Cyclone separator; 7. End expansion type gradient structure; 8. Ammonia fuel jet pyrolysis zone; 9. Annular air curtain; 10. High temperature entrainment reflux zone; 11. Combustion burnout zone. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model. Furthermore, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.
[0020] In the description of this utility model, it should be understood that, unless otherwise explicitly specified and limited, the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0021] Furthermore, unless otherwise expressly defined, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.
[0022] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0023] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0024] Below, for reference Figures 1-4 This invention describes a fuel gas ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis according to a preferred embodiment of the present invention.
[0025] like Figure 1 As shown, the fuel gas ammonia-blended low-NOx burner in the preferred embodiment includes an adjustable ammonia fuel pipe 1 located at the center, and a circulating flue gas pipe 2, a fuel gas pipe 3, an inner swirling combustion-supporting air pipe 4, and an outer swirling combustion-supporting air pipe 5 sequentially arranged around the adjustable ammonia fuel pipe 1. The pipes are preferably coaxially arranged, and from the inside out, a circulating flue gas passage, a fuel gas passage, an inner swirling combustion-supporting air passage, and an outer swirling combustion-supporting air passage are formed between adjacent pipes, respectively used for conveying low-oxygen flue gas, fuel gas, inner swirling combustion-supporting air passage, and outer swirling combustion-supporting air passage to the combustion chamber.
[0026] Specifically, both the inner swirling combustion-supporting gas passage and the outer swirling combustion-supporting gas passage are used to introduce combustion-supporting gas into the combustion chamber and form a high-temperature entrainment recirculation zone 10 in the combustion chamber. Meanwhile, the outlet end of the adjustable ammonia fuel pipe 1 extends into the high-temperature entrainment recirculation zone 10, and its tail end away from the combustion chamber is connected to a drive mechanism (not shown in the figure), so that the adjustable ammonia fuel pipe 1 can be moved back and forth axially relative to the circulating flue gas pipe 2 under the drive of the drive mechanism, so as to adjust the injection position of ammonia fuel in the combustion chamber.
[0027] Correspondingly, the circulating flue gas channel formed between the circulating flue gas pipe 2 and the adjustable ammonia fuel pipe 1 is an annular cavity, used to inject high-speed, low-oxygen flue gas into the combustion chamber. An annular air curtain 9 is formed around the ammonia fuel injected into the combustion chamber to separate the unpyrolyzed ammonia fuel from the high-temperature entrainment recirculation zone 10. A pyrolysis transport channel for the ammonia fuel is formed within the annular air curtain 9, ensuring that the unpyrolyzed ammonia fuel can be injected independently into the high-temperature entrainment recirculation zone 10, ensuring sufficient time for in-situ pyrolysis of the ammonia fuel, and effectively preventing contact between the unpyrolyzed ammonia fuel and the high-temperature entrainment recirculation zone 10, thereby preventing contact between the unpyrolyzed ammonia fuel and oxygen in the recirculation, thus inhibiting the oxidation reaction of the ammonia fuel and controlling NO. x The purpose of generation.
[0028] The formation of the annular air curtain 9 effectively increases the rigidity of the ammonia fuel jet, preventing the ammonia fuel from being directly entrained into the primary air outlet area of the burner (i.e., the outlet of the internal swirling combustion air duct 4). Simultaneously, an ammonia fuel jet pyrolysis zone 8 is formed at the tail end of the ammonia fuel pyrolysis transmission channel, such as... Figure 1 As shown in the image.
[0029] With the aforementioned burner configuration, ammonia fuel is introduced into the combustion chamber through an adjustable ammonia fuel pipe 1 extending into the high-temperature entrainment recirculation zone 10. The ammonia fuel is separated from the high-temperature entrainment recirculation zone 10 by an annular air curtain 9 formed by the circulating flue gas, so that the ammonia fuel can be deeply decomposed into hydrogen and nitrogen when passing through the high-temperature entrainment recirculation zone 10. At the tail end of the high-temperature entrainment recirculation zone 10, the decomposed ammonia fuel is entrained into the fuel gas jet region by the swirling effect.
[0030] By setting the outlet of the adjustable ammonia fuel pipe 1 in the high-temperature entrainment reflux zone 10, the thermal environment at the ammonia fuel injection point can be changed accordingly, thereby controlling the degree of in-situ ammonia cracking and ensuring complete pyrolysis of the ammonia fuel. Moreover, under the condition of deep pyrolysis of ammonia fuel, the hydrogen produced by pyrolysis is further mixed with the fuel gas through entrainment reflux. The high activity and high flame velocity of hydrogen greatly improve the ignition characteristics of the fuel gas, ensuring combustion stability and effectively preventing flameout.
[0031] In addition, the central ammonia jet and the annular natural gas jet shear and collide with each other under the action of strong internal swirling flow and mix with the combustion-supporting gas. The mixing effect is far greater than that of a single fuel jet, and the combustion effect is further enhanced.
[0032] More specifically, in the preferred embodiment, the adjustable ammonia fuel pipe 1 is preferably a multi-layer channel structure, which includes a central conveying channel and at least one annular conveying channel formed outside the central conveying channel.
[0033] By utilizing the multi-layer delivery channel, the ammonia fuel in the adjustable ammonia fuel pipe 1 can be divided into different injection layers in the radial direction, and different injection flow rates and injection speeds can be adjusted as needed. This achieves the purpose of flexibly adjusting the ammonia fuel injection flow rate and injection speed according to the combustion conditions in the combustion chamber. Furthermore, it adjusts the degree of in-situ cracking of ammonia fuel in the combustion chamber and changes the hydrogen concentration at the outlet of the entrained fuel gas pipe 3, ultimately achieving the purpose of adjusting the combustion conditions in the combustion chamber.
[0034] In practical setups, for multi-layered conveying channels, separate ammonia fuel conveying pipelines can be installed for each channel. The multi-stage control of ammonia fuel transmission parameters (flow rate / velocity) within each pipeline can be adjusted. Alternatively, a multi-port valve can be installed on a single ammonia fuel conveying pipeline, correspondingly controlling the cross-sectional area of different conveying channels to adjust the ammonia fuel transmission characteristics within each radial conveying channel.
[0035] As an example, in a preferred embodiment, the adjustable ammonia fuel pipe 1 preferably includes an inner ammonia fuel pipe 101 and an outer ammonia fuel pipe 102 arranged coaxially, such as... Figure 1 As shown in the figure. The inner ammonia fuel pipe 101 and the outer ammonia fuel pipe 102 can perform synchronous reciprocating motion in the axial direction under the drive of the drive mechanism; and the injection flow rate and injection speed of ammonia fuel in the inner ammonia fuel pipe 101 and the outer ammonia fuel pipe 102 are adjustable.
[0036] By utilizing the corresponding configuration of the inner and outer ammonia fuel pipes, the ammonia fuel flow rates on both sides can be flexibly adjusted. For example, when the ammonia blending amount is relatively small, the flow rate in the inner ammonia fuel transmission channel can be increased as much as possible while the flow rate in the outer ammonia fuel transmission channel can be decreased, thereby increasing the injection velocity and injection momentum at the outlet of the inner ammonia fuel transmission channel. When the ammonia blending amount is relatively large, while ensuring the flow rate in the inner ammonia fuel transmission channel, the flow rate in the outer ammonia fuel transmission channel can be appropriately increased to avoid excessive overall flow velocity at the outlet of the adjustable ammonia fuel pipe 1. This would prevent the ammonia fuel from being transported to the combustible combustion zone 11 without pyrolysis and mixing, resulting in reduced ammonia combustion efficiency due to excessive ammonia fuel injection distance.
[0037] As an example, a three-way flow valve is installed on the ammonia fuel delivery pipeline. The inlet of the three-way flow valve is connected to the ammonia fuel delivery pipeline, and the two outlets of the three-way flow valve are connected to the inner ammonia fuel pipe 101 and the outer ammonia fuel pipe 102, respectively. By controlling the three-way flow valve, the flow rate of ammonia fuel in the inner and outer channels can be adjusted. Under the condition that the initial gas pressure is the same, by controlling the flow rate of ammonia fuel entering the two channels, and in combination with the design of the cross-sectional area of the two channels, the control of the ammonia fuel transmission status in the two channels can be accurately completed.
[0038] More specifically, the ratio of the cross-sectional area of the inner cavity of the inner ammonia fuel pipe 101 to the cross-sectional area of the annular cavity formed between the outer ammonia fuel pipe 102 and the inner ammonia fuel pipe 101 is 1:1 to 4:1. More preferably, the cross-sectional area of the inner cavity of the inner ammonia fuel pipe 101 is not less than the cross-sectional area of its outer annular cavity, and in this case, the ratio of their cross-sectional areas is further preferably 1:1 to 2:1.
[0039] Meanwhile, to ensure the rigidity of the annular air curtain 9 after its formation, in the preferred embodiment, the flue gas transmitted through the circulating flue gas pipe 2 is high-speed, low-oxygen flue gas. Its injection speed is determined by the entrainment force of the high-temperature entrainment return zone 10 and the ammonia fuel injection speed, thus meeting the separation requirements of the annular air curtain 9. In actual control, the NO content in the exhaust gas can be detected. x The specific flow rate of high-speed, low-oxygen flue gas is controlled by concentration; that is, if the NO in the exhaust gas... x Increasing this further increases the flow rate of the high-speed, low-oxygen flue gas.
[0040] More specifically, for the case where the adjustable ammonia fuel pipe 1 is configured as an inner and outer pipe, in the preferred embodiment, the control of the gas flow rate in each pipe preferably satisfies the following conditions: The flow velocity of ammonia fuel in the inner ammonia fuel pipe 101 is not less than the flow velocity of high-speed low-oxygen flue gas, and the flow velocity of high-speed low-oxygen flue gas is 1.2 to 3 times the flow velocity of ammonia fuel in the outer ammonia fuel pipe 102, more preferably 1.5 times.
[0041] The aforementioned control over the flow rates of various gases is intended to effectively ensure the rigidity of the gas column during the transport of ammonia fuel and high-speed, low-oxygen flue gas. This ensures that the annular air curtain 9 can reliably separate the high-temperature entrainment recirculation zone 10 from the ammonia fuel, while also guaranteeing reliable transmission of the ammonia fuel within a certain distance. This achieves the goal of controlling the formation position of the ammonia fuel jet pyrolysis zone 8. Simultaneously, based on the control of the high-speed, low-oxygen flue gas flow rate and the ammonia fuel flow rate in the inner and outer ammonia fuel pipes 101 and 102, a ring of slower-flowing ammonia fuel is formed between the central ammonia fuel and the annular air curtain 9. This arrangement minimizes the mutual influence between the main ammonia fuel transport and the annular air curtain 9, effectively creating a lubricating layer for the high-speed, low-oxygen flue gas and central ammonia fuel transport, thereby improving the reliability and stability of the high-speed, low-oxygen flue gas and central ammonia fuel transport and avoiding mutual interference caused by direct contact between the two.
[0042] Furthermore, in the preferred embodiment, the burner also includes an end expansion gradient structure 7 disposed at the end of each pipe other than the adjustable ammonia fuel pipe 1 that connects to the combustion chamber, so that the direction of the fuel gas and combustion gas output from the burner outlet is not parallel to the axial direction of the burner, which is more conducive to the formation of the high-temperature entrainment recirculation zone 10.
[0043] Specifically, the end-expansion gradient structure 7 preferably consists of a variable-diameter inner cavity (i.e., a flared opening at the end of the inner cavity) formed on at least a portion of the inner circumferential wall of the pipe end and / or a variable-diameter end on at least a portion of the outer circumference of the pipe end. The inner diameter of the variable-diameter inner cavity increases sequentially from the middle of the pipe towards the end; the outer diameter of the variable-diameter end also increases sequentially from the middle of the pipe towards the end.
[0044] By utilizing the aforementioned end-expansion gradient structure 7, the entrainment effect of high-temperature flue gas in the combustion chamber is further enhanced, thereby improving the mixing effect between combustion gas, combustion air, and cracked combustible gas, thus achieving the goal of enhancing combustion conditions.
[0045] However, due to the increased entrainment effect of high-temperature flue gas, the possibility of premature mixing between ammonia fuel and high-temperature flue gas increases significantly. This leads to the ammonia fuel not having enough time to completely pyrolyze and undergoing an oxidation reaction, resulting in NO... x The increase in NO. Therefore, the preferred embodiment incorporates the design of adjustable ammonia fuel pipe 1's extension and retraction control, multi-stage conveying and regulation of ammonia fuel in the adjustable ammonia fuel pipe 1, and an annular air curtain 9 formed by introducing low-oxygen flue gas. Through this combination of designs, the final goal is to both enhance combustion efficiency and prevent NO. x The purpose of the increase.
[0046] More preferably, the diameter change angle of the aforementioned variable diameter inner cavity and / or variable diameter end relative to the pipe axis is 0° to 45°, and more specifically preferably 20°.
[0047] More preferably, cyclones 6 are provided in the inner and outer cyclone combustion-supporting channels to introduce combustion air into the combustion chamber in a cyclone form.
[0048] As an example, cyclone 6 is an axial blade cyclone with a fixed blade angle (e.g., set to 30°). Alternatively, as another example, the cyclone blade angle is adjustable to achieve independent control of the backflow intensity and mixing intensity.
[0049] More specifically, in the preferred embodiment, the driving mechanism for driving the adjustable ammonia fuel pipe 1 is an electric push rod, a precision lead screw and nut mechanism driven by a servo motor, or a hydraulic cylinder, which can achieve accurate control of the axial position of the adjustable ammonia fuel pipe 1.
[0050] Furthermore, for the fuel gas that is mixed and burned with ammonia fuel in the preferred embodiment, it is preferably natural gas, that is, the fuel gas introduced through the fuel gas pipe 3 in the preferred embodiment is natural gas.
[0051] Of course, in addition to natural gas, other gaseous fuels can also be selected as needed, such as a mixture of multiple fuel gases.
[0052] For the ammonia-blended low-NOx burner based on in-situ ammonia pyrolysis in the preferred embodiment, a high-temperature entrainment recirculation zone 10 is formed in the burner outlet area through the inner swirl combustion air duct 4 and the outer swirl combustion air duct 5. The outlet of the adjustable ammonia fuel pipe 1 extends into the high-temperature entrainment recirculation zone 10, effectively preventing the injected ammonia fuel from being directly entrained to the outlet area of the inner and outer swirl air ducts, thus inhibiting the oxidation reaction of the ammonia fuel. At the same time, high-speed low-oxygen flue gas is injected through the circulating flue gas duct 2, forming an airflow protection layer (i.e., an annular air curtain 9) on the outside of the ammonia fuel transmission path. This enhances the rigidity of the ammonia fuel jet in the area outside the ammonia fuel transmission path, allowing the ammonia fuel to be ejected independently over a longer distance, providing sufficient time for in-situ pyrolysis. This further avoids contact between unpyrolyzed ammonia fuel and oxygen in the combustion air, inhibiting the oxidation reaction of the ammonia fuel, thereby further controlling NO. x The purpose of generation.
[0053] Furthermore, for the aforementioned burner, the method for performing low-NOx combustion of fuel gas with ammonia preferably includes the following process: The position of the outlet of the adjustable ammonia fuel pipe 1 into the high-temperature entrainment recirculation zone 10 is adjusted by the drive mechanism. Ammonia fuel, low-oxygen flue gas, fuel gas, internal swirling combustion-supporting gas and external swirling combustion-supporting gas are introduced into the combustion chamber from each pipe and ignited in the combustion chamber. When the combustion conditions are unstable and it is necessary to improve the flame stability, the adjustable ammonia fuel pipe 1 is controlled to extend forward into the high-temperature core area of the high-temperature entrainment recirculation zone 10 to enhance the in-situ cracking of ammonia fuel and increase the hydrogen concentration mixed with fuel gas at the root of the flame. When it is necessary to reduce NO x When controlling emissions, the adjustable ammonia fuel pipe 1 extends further into the high-temperature core area of the high-temperature entrainment recirculation zone 10, while simultaneously increasing the ammonia fuel injection velocity to prevent the ammonia fuel from being directly oxidized by the high-temperature flue gas entrainment recirculation and oxygen to generate NO. x .
[0054] As described above, the length of the adjustable ammonia fuel pipe 1 extending into the high-temperature entrainment recirculation zone 10 should not be too long, and the injection velocity of the ammonia fuel should not be too high. Otherwise, unburned ammonia fuel may be directly injected into the combustible combustion zone 11, resulting in a reduction in the combustion efficiency of the ammonia fuel. In actual installation, the extension length of the adjustable ammonia fuel pipe 1 and the injection velocity of the ammonia fuel are adjusted according to the formation position of the ammonia fuel jet pyrolysis zone 8. The formation position of the ammonia fuel jet pyrolysis zone 8 is preferably located at the tail end of the high-temperature entrainment recirculation zone 10 (the end away from the burner), and does not exceed the tail end of the high-temperature entrainment recirculation zone 10. In this way, the in-situ cracking of the ammonia fuel can be fully guaranteed, and the introduced ammonia fuel can be effectively entrained and recirculated to the fuel gas injection area, thereby achieving the purpose of enhancing the combustion intensity of the fuel gas.
[0055] Based on the aforementioned control design of the burner, a single burner can adapt to a wide range of ammonia blending ratio changes and operate under all conditions from low load to full load without requiring shutdown for mechanical modifications, effectively improving the applicability of the burner.
[0056] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A fuel gas with ammonia based on ammonia in-situ cracking ammonia-doped low-nitrogen combustor, characterized in that, It includes an adjustable ammonia fuel pipe located at the center, and a circulating flue gas pipe, a fuel gas pipe, an inner swirl combustion air pipe and an outer swirl combustion air pipe sequentially arranged around the adjustable ammonia fuel pipe. From the inside to the outside, a circulating flue gas passage, a fuel gas passage, an inner swirl combustion air passage and an outer swirl combustion air passage are formed between adjacent pipes. The inner swirling combustion-supporting gas channel and the outer swirling combustion-supporting gas channel are used to introduce combustion-supporting gas into the combustion chamber and form a high-temperature entrainment and recirculation zone in the combustion chamber. The outlet end of the adjustable ammonia fuel pipe extends into the high-temperature entrainment recirculation zone, and its tail end away from the combustion chamber is connected to a drive mechanism, which allows the adjustable ammonia fuel pipe to move back and forth axially under the drive of the drive mechanism to adjust the injection position of ammonia fuel in the combustion chamber. The circulating flue gas channel is an annular cavity used to inject high-speed, low-oxygen flue gas into the combustion chamber and form an annular air curtain around the ammonia fuel injected into the combustion chamber to separate the unpyrolyzed ammonia fuel from the high-temperature entrainment recirculation zone.
2. The ammonia-doped, low-NOx combustor based on in-situ ammonia- cracking of fuel gas according to claim 1, characterized in that The adjustable ammonia fuel pipe has a multi-channel structure, including a central conveying channel and at least one annular conveying channel formed outside the central conveying channel.
3. The fuel gas based ammonia split for nitrogen low-NOx combustor of claim 2, wherein, The adjustable ammonia fuel pipe includes an inner ammonia fuel pipe and an outer ammonia fuel pipe arranged coaxially. The inner ammonia fuel pipe and the outer ammonia fuel pipe can perform synchronous reciprocating motion in the axial direction under the drive mechanism; and the injection flow rate and injection speed of ammonia fuel in the inner ammonia fuel pipe and the outer ammonia fuel pipe are adjustable.
4. The fuel gas based ammonia split for nitrogen low-NOx combustor of claim 3, wherein, A three-way flow valve is installed on the ammonia fuel delivery pipeline; the inlet of the three-way flow valve is connected to the ammonia fuel delivery pipeline, and the two outlets of the three-way flow valve are respectively connected to the inner ammonia fuel pipeline and the outer ammonia fuel pipeline. and / or The ratio of the cross-sectional area of the inner cavity of the inner ammonia fuel pipe to the cross-sectional area of the annular cavity formed between the outer ammonia fuel pipe and the inner ammonia fuel pipe is 1:1 to 4:
1. and / or The flow velocity of ammonia fuel in the inner ammonia fuel pipe is not less than the flow velocity of the high-speed low-oxygen flue gas, and the flow velocity of the high-speed low-oxygen flue gas is 1.2 to 3 times the flow velocity in the outer ammonia fuel pipe.
5. The fuel gas based ammonia-splitting in-situ ammonia-doping low-NOx combustor according to any one of claims 1 to 4, characterized in that, It also includes an end-expansion gradient structure installed at one end of each pipe other than the adjustable ammonia fuel pipe that connects to the combustion chamber; The end-expansion gradient structure consists of a variable-diameter inner cavity formed on at least part of the inner circumferential wall of the pipe end and / or a variable-diameter end on at least part of the outer circumference of the pipe end; the inner diameter of the variable-diameter inner cavity increases sequentially from the middle of the pipe to the end; the outer diameter of the variable-diameter end increases sequentially from the middle of the pipe to the end.
6. The fuel gas based ammonia split for nitrogen low-NOx combustor of claim 5, wherein, The diameter-changing inner cavity and / or the diameter-changing end have a diameter-changing angle of 0° to 45° relative to the pipe axis.
7. The fuel gas based ammonia-splitting in-situ ammonia-doping low-NOx combustor according to any one of claims 1 to 4, 6, characterized in that, The inner and outer swirling combustion-supporting channels are equipped with swirlers to introduce combustion-supporting air into the combustion chamber in a swirling manner.
8. The ammonia-doped, low-NOx combustor based on in-situ ammonia- splitting fuel gas of claim 7, wherein, The cyclone separator is an axial blade cyclone separator with adjustable blade angle, used to achieve independent control of the backflow intensity and mixing intensity.
9. The fuel gas based ammonia-splitting in-situ ammonia-doping low-NOx combustor according to any one of claims 1 to 4, 6, 8, characterized in that, The drive mechanism is an electric push rod, a precision lead screw and nut mechanism driven by a servo motor, or a hydraulic cylinder; and / or The fuel gas introduced into the fuel gas pipe is natural gas.