Ammonia-blended fuel multi-stage micro-decomposition swirl burner and low no x emission control method

Abstract

An ammonia-blended fuel multi-stage micro-decomposition swirl burner (100) and a low NOx emission control method. The burner (100) is provided with a natural gas center pipe (1), a primary air pipe (2), and a burner housing (3) which are sequentially nested from inside to outside to form a primary air duct (4) and an overfire air duct (5) isolated from each other; natural gas is ejected from the natural gas center pipe (1); swirl vanes (7) are provided in the primary air duct (4), so that primary air can be mixed with central natural gas in a swirling state; then a diffusion flame is formed under the action of an ignition device (6); and a continuously burning pilot flame is formed in the center of an ejection end of the burner (100). Ammonia gas and natural gas are premixed to form ammonia-blended fuel, then the ammonia-blended fuel is ejected at a high speed through micro-decomposition holes (81), so as to form negative pressure to continuously entrain surrounding overfire air, meanwhile, the ammonia-blended fuel is ejected into a pilot flame high-temperature burning area in the center of the burner, so that ammonia is rapidly decomposed, a large amount of generated hydrogen is conducive to improving the burning stability, and NOx emission is reduced.

Description

A multi-stage micro-decomposition swirl burner for ammonia-blended fuel and low NO x Control methods Technical Field

[0001] The present invention belongs to the field of combustion equipment, and relates to a burner for burning gas fuel, and in particular to a multi-stage micro-decomposition swirl burner for ammonia-blended fuel and a low NO x Control method. Background Art

[0002] In the combustion of premixed swirl burner, the mixing ratio and mixing uniformity of ammonia-blended fuel and oxidant directly determine the NO x (Combustion of nitrogen oxides) emission effect. Existing swirl burners have poor flame effects and high nitrogen oxide emissions due to insufficient mixing of ammonia-blended fuel and oxidant, which can no longer meet current safety and environmental protection requirements for burners.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-stage micro-decomposition swirl burner for ammonia-blended fuel and a low NO x control method, its combustion stability is high, NO x The emission is low, so as to solve the problems of the above-mentioned existing burners, that is, insufficient mixing of ammonia-blended fuel and oxidant, unsatisfactory flame effect and high nitrogen oxide emission.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides an ammonia-blended fuel multi-stage micro-decomposition swirl burner, comprising a natural gas central tube, a primary air duct, and a burner housing, which are sequentially sleeved from the inside to the outside. A primary air duct is formed between the outer wall of the natural gas central tube and the inner wall of the primary air duct, and a burnout air channel is formed between the outer wall of the primary air duct and the inner wall of the burner housing.

[0007] An ignition device and a swirl blade are provided in the primary air duct. The swirl blade is installed on the outer periphery of the outlet end of the natural gas central pipe. The swirl blade is used to mix the primary air in the primary air duct with the natural gas ejected from the outlet end of the natural gas central pipe in a swirling state. The ignition device is used to ignite the mixed primary air and natural gas to form a sustainable burning service flame at the outlet end of the natural gas central pipe.

[0008] A fuel distribution nozzle is provided in the burnout air channel. The fuel distribution nozzle is provided near the outlet end of the natural gas central pipe. The outlet end of the fuel distribution nozzle is provided with a plurality of micro-decomposition holes to eject the ammonia-blended fuel at high speed, so that the ammonia in the ammonia-blended fuel burns under the action of the duty flame, and when the ammonia-blended fuel is ejected at high speed, negative pressure is formed at the port of the burnout air channel, sucking in the burnout air formed by the combustion of the ammonia-blended fuel.

[0009] Optionally, the outer wall of the primary air duct is further provided with a primary air distribution pipe connected to the primary air duct, the primary air distribution pipe is located in the burnout air channel, the outlet end of the primary air distribution pipe is located at the periphery of the outlet end of the primary air duct, and the outlet end of the primary air distribution pipe is longer than the outlet ends of the natural gas central pipe and the primary air duct.

[0010] Optionally, a distribution pipe nozzle is provided at the outlet end of the primary air distribution pipe, and the axial angle between the distribution pipe nozzle and the primary air pipe is adjustable.

[0011] Optionally, a plurality of primary air distribution pipes are evenly distributed on the outer wall of the primary air duct along its circumference.

[0012] Optionally, a plurality of the fuel distribution nozzles are provided in the burnout air channel, and all the fuel distribution nozzles are evenly distributed around the circumference of the primary air duct; the micro-decomposition holes in any of the fuel distribution nozzles are evenly distributed.

[0013] Optionally, the ignition device is an ignition gun.

[0014] Optionally, the swirl blades include a plurality of circumferentially spaced swirl blades, and an axial angle between any one of the swirl blades and the primary air duct is 30° to 45°.

[0015] Optionally, the diameter of any one of the micro-decomposition pores is 3 mm to 7 mm.

[0016] The present invention also proposes a low NO x The control method is implemented using an ammonia-blended fuel multi-stage micro-decomposition swirl burner as described in any one of the above items, including: injecting a portion of natural gas accounting for 20% by volume through the outlet end of the natural gas center tube, and mixing and burning with the primary air under the action of the ignition device to form the on-duty flame; premixing an ammonia-blended fuel formed by premixing an 80% by volume portion of natural gas with ammonia at a preset equivalence ratio, and then injecting it into the flame zone formed by the on-duty flame through the fuel distribution nozzle, so that the ammonia in the ammonia-blended fuel burns and decomposes under the action of the on-duty flame.

[0017] Optionally, during the combustion of the ammonia-blended fuel, the overall equivalence ratio of the ammonia-blended fuel and the ammonia-blended fuel multi-stage differential decomposition swirl burner is controlled in a lean burn state, and the local equivalence ratio of the burnout air and the ammonia-blended fuel is controlled in a rich burn state.

[0018] Optionally, during the combustion of the ammonia-blended fuel, the overall equivalence ratio of the ammonia-blended fuel and the ammonia-blended fuel multi-stage differential decomposition swirl burner is controlled at 0.7-0.8, and the local equivalence ratio of the burnout air to the ammonia-blended fuel is controlled at 1.0-1.3.

[0019] Compared with the prior art, the present invention has achieved the following technical effects:

[0020] The ammonia-blended fuel multi-stage micro-decomposition swirl burner proposed in the present invention forms a mutually isolated primary air duct and burnout air duct by stacking the natural gas central tube, the primary air duct and the burner shell in sequence from the inside to the outside. Natural gas is ejected from the natural gas central tube, and the swirl blades are arranged in the primary air duct and are located around the natural gas central tube, so that the primary air can be mixed with the central natural gas in a swirl state, and then a diffusion flame is formed under the action of the ignition device. In this way, a sustainable burning service flame is formed at the center of the injection end of the ammonia-blended fuel multi-stage micro-decomposition swirl burner; ammonia and natural gas are premixed to form ammonia-blended fuel, and are ejected at high speed through the micro-decomposition holes, forming a negative pressure that continuously entrains the surrounding burnout air. At the same time, the ammonia-blended fuel is injected into the high-temperature combustion area of ​​the service flame in the center of the burner, so that ammonia is quickly decomposed, and the large amount of hydrogen produced helps to improve combustion stability. The ammonia-blended fuel multi-stage micro-decomposition swirl burner has a novel and reasonable structural arrangement, which can improve combustion stability and reduce NO x emission.

[0021] In some technical solutions disclosed in the present invention, a primary air distribution pipe with an adjustable nozzle angle is arranged outside the primary air duct, and the outlet end of the primary air distribution pipe is longer than the outlet ends of the natural gas central pipe and the primary air duct, so that part of the primary air can be delayed in entering the combustion area to ensure sufficient combustion of the fuel and further improve combustion stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] FIG1 is a schematic structural diagram of a multi-stage micro-decomposition swirl burner for ammonia-blended fuel disclosed in an embodiment of the present invention;

[0024] FIG2 is a front view of the ammonia-blended fuel multi-stage micro-decomposition swirl burner disclosed in an embodiment of the present invention;

[0025] FIG3 is a side view of the ammonia-blended fuel multi-stage micro-decomposition swirl burner disclosed in an embodiment of the present invention.

[0026] Among them, the accompanying drawings are marked as: 100, ammonia-blended fuel multi-stage micro-decomposition swirl burner; 1, natural gas center pipe; 2, primary air duct; 3, burner shell; 4, primary air duct; 5, burnout air channel; 6, ignition device; 7, swirl blade; 8, fuel distribution nozzle; 81, micro-decomposition hole; 9, fuel inlet pipe; 10, primary air distribution pipe; 11, blunt body. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] One of the purposes of the present invention is to provide a multi-stage micro-decomposition swirl burner for ammonia-blended fuel, which has high combustion stability and NO x The low emission can solve the problems of existing burners such as insufficient mixing of ammonia-blended fuel and oxidant, unsatisfactory flame effect and high nitrogen oxide emission.

[0029] Another object of the present invention is to provide a low NOx burner based on the multi-stage micro-decomposition swirl burner of ammonia-blended fuel. x Combustion control method with high combustion stability, NO x The low emission can solve the problems of existing burners such as insufficient mixing of ammonia-blended fuel and oxidant, unsatisfactory flame effect and high nitrogen oxide emission.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] As shown in Figures 1 to 3, this embodiment provides an ammonia-blended fuel multi-stage micro-decomposition swirl burner 100, comprising a natural gas central tube 1, a primary air duct 2, and a burner housing 3, which are sequentially arranged from the inside to the outside. A primary air duct 4 is formed between the outer wall of the natural gas central tube 1 and the inner wall of the primary air duct 2, and a burnout air channel 5 is formed between the outer wall of the primary air duct 2 and the inner wall of the burner housing 3. An ignition device 6 and a swirl blade 7 are provided in the primary air duct 4. The swirl blade 7 is installed on the outer periphery of the outlet end of the natural gas central tube 1. The swirl blade 7 is used to make the primary air in the primary air duct 4 swirl and mix with the natural gas. The natural gas mixture injected from the outlet end of the central tube 1 is used, and the ignition device 6 is used to ignite the mixed primary air and natural gas to form a sustainable burning service flame at the outlet end of the natural gas central tube 1; a fuel distribution nozzle 8 is provided in the burnout air channel 5, and the fuel distribution nozzle 8 is provided close to the outlet end of the natural gas central tube 1. The outlet end of the fuel distribution nozzle 8 is provided with a plurality of micro-decomposition holes 81 to eject the ammonia-blended fuel at high speed, so that the ammonia in the ammonia-blended fuel burns under the action of the service flame, and when the ammonia-blended fuel is ejected at high speed, a negative pressure is formed at the port of the burnout air channel 5, thereby sucking in the burnout air formed by the combustion of the ammonia-blended fuel.

[0033] In this embodiment, the outer wall of the primary air duct 2 is further provided with a primary air distribution pipe 10 connected to the primary air duct 4. The primary air distribution pipe 10 is located within the burnout air channel 5. The outlet end of the primary air distribution pipe 10 is located outside the outlet end of the primary air duct 2. The outlet end of the primary air distribution pipe 10 is longer than the outlet ends of the natural gas central pipe 1 and the primary air duct 2. This allows the primary air ejected through the primary air distribution pipe 10 to enter the combustion area later than the primary air ejected from the primary air duct 2, thereby ensuring sufficient combustion of the fuel. The inlet end of the primary air distribution pipe 10 is generally connected to a position near the rear end of the primary air duct 2. Once primary air enters the primary air duct 2, it immediately flows into the primary air distribution pipe 10.

[0034] In this embodiment, a distribution pipe nozzle is provided at the outlet end of the primary air distribution pipe 10, and the axial angle between the distribution pipe nozzle and the primary air pipe 2 is adjustable, and the adjustment angle is generally -45° to 45°. Regarding the angle adjustment of the distribution pipe nozzle, a nozzle with an angle adjustment function can be directly used, such as a universal nozzle, a spherical angle adjustment nozzle disclosed in patent CN95106474.6, etc., or the nozzle can be installed using an existing injection angle adjustment structure, and the injection angle adjustment structure is used to adjust the axial angle between the distribution pipe nozzle and the primary air pipe 2. The injection angle adjustment structure can adopt a universal valve, a universal regulator, the structure disclosed in patent CN101121157A, etc.

[0035] In this embodiment, the ratio of the air flow rate flowing through any primary air distribution pipe 10 to the total primary air is the ratio of the cross-sectional area of ​​the primary air distribution pipe 10 to the cross-sectional area of ​​the primary air duct 2 .

[0036] In this embodiment, a plurality of primary air distribution pipes 10 are evenly distributed along the circumference of the outer wall of the primary air duct 2 .

[0037] In this embodiment, multiple fuel distribution nozzles 8 are installed within the burnout air channel 5, and all fuel distribution nozzles 8 are evenly distributed around the circumference of the primary air duct 2. The micro-decomposition holes 81 in each fuel distribution nozzle 8 are evenly distributed, ensuring a uniform flow field distribution at the burner outlet. As a further preferred embodiment, the fuel distribution nozzles 8 are distributed around the periphery of multiple primary air distribution pipes 10, as shown in Figures 1 and 2, with the outlet ends of the primary air distribution pipes 10 being longer than those of the fuel distribution nozzles 8.

[0038] In this embodiment, each fuel distribution nozzle 8 is also connected to a fuel inlet pipe 9. The fuel inlet pipes 9 connected to all fuel distribution nozzles 8 are preferably of equal diameter, parallel to each other, and evenly spaced. The load of the ammonia-blended fuel multi-stage micro-decomposition swirl burner 100 can be adjusted by the number of fuel inlet pipes 9 that are open.

[0039] In this embodiment, the ignition device 6 is preferably an ignition gun. After the ignition is completed, the ignition gun can be used as an intake channel for other fuels.

[0040] In this embodiment, the swirl blades 7 include a plurality of circumferentially spaced swirl blades, and the axial angle between any swirl blade and the primary air duct 2 is 30° to 45°.

[0041] In this embodiment, the diameter of any micro-decomposition hole 81 is 3 mm to 7 mm. Furthermore, the diameter of any micro-decomposition hole 81 can be 3 mm, 5 mm or 7 mm.

[0042] In this embodiment, the natural gas central pipe 1 is an overall curved pipe structure. One end of the pipe is located coaxially within the primary air duct 2, while the other end extends through the sidewall of the primary air duct 2 and outward, as shown in Figures 1-3. This structural arrangement facilitates simultaneous ventilation of the natural gas central pipe 1 and the primary air duct 2, preventing interference between the two. The inner wall of the outlet end of the natural gas central pipe 1 is configured in the shape of a bluff body 11 to conform to bluff body aerodynamics. The configuration of the bluff body 11 is a conventional technique in the burner field and will not be further described here.

[0043] The above-mentioned ammonia-blended fuel multi-stage micro-decomposition swirl burner 100 is formed by stacking the natural gas central pipe 1, the primary air pipe 2 and the burner shell 3 from the inside to the outside, forming a mutually isolated primary air duct 4 and a burnout air duct 5. Natural gas is ejected from the natural gas central pipe 1, and this portion of natural gas accounts for about 20% of the volume. The swirl blades 7 are arranged in the primary air duct 4 and located around the natural gas central pipe 1, which can mix the primary air with the central natural gas in a swirl state, and then form a diffusion flame under the action of the ignition device 6. In this way, a sustainable burning service flame is formed at the center of the injection end of the ammonia-blended fuel multi-stage micro-decomposition swirl burner 100. A primary air distribution pipe 10 with an adjustable nozzle angle is arranged outside the primary air pipe 2, and the outlet end of the primary air distribution pipe 10 is longer than the outlet ends of the natural gas central pipe 1 and the primary air pipe 2, which can delay the entry of part of the primary air into the combustion area to ensure sufficient combustion of the fuel. Several fuel distribution nozzles 8, each consisting of a plurality of micro-decomposition holes 81, are arranged on the periphery of the primary air distribution pipe 10. 100% ammonia is premixed with the remaining 80% natural gas to form an ammonia-blended fuel. After being rectified by the fuel inlet pipe 9 connected to the fuel distribution nozzle 8, the fuel is ejected from the micro-decomposition holes 81 at high speed, creating a negative pressure that continuously draws in the surrounding burnout air. At the same time, the ammonia-blended fuel is injected into the high-temperature combustion area of ​​the on-duty flame in the center of the burner, causing ammonia to decompose rapidly. The large amount of hydrogen produced helps to improve combustion stability. During the combustion of the ammonia-blended fuel, the overall equivalence ratio of the ammonia-blended fuel to the ammonia-blended fuel multi-stage micro-decomposition swirl burner 100 is generally controlled to be in a lean burn state, for example, the overall equivalence ratio of the ammonia-blended fuel to the ammonia-blended fuel multi-stage micro-decomposition swirl burner 100 is controlled to be in a 0.7-0.8 state, and the local equivalence ratio of the burnout air to the ammonia-blended fuel is controlled to be in a rich burn state, for example, the local equivalence ratio of the burnout air to the ammonia-blended fuel is controlled to be in a 1.0-1.3 state. As a further preferred solution, during the combustion of ammonia-blended fuel, the local equivalence ratio of the burnout air to the ammonia-blended fuel is generally controlled to be around 1.2.

[0044] It can be seen that in the multi-stage micro-decomposition swirl burner 100 of ammonia-blended fuel proposed in this technical solution, during operation, the central part of the natural gas and the swirl air first form a stable high-temperature service flame under the action of the ignition device 6, and the remaining natural gas is premixed with ammonia and then injected into the high-temperature zone formed by the high-temperature service flame through the micro-decomposition hole 81 at a certain equivalence ratio. In combination with the setting of the primary air distribution pipe, it can improve the combustion stability and reduce NO on the basis of achieving fuel burnout. x Compared with the existing technology, this technical solution has the following beneficial technical effects:

[0045] (1) A method for achieving NO x The precisely controlled multi-stage micro-decomposition swirl burner for ammonia-blended fuel can solve the current NO x The problem of high emissions.

[0046] (2) During combustion, the flame area is composed of different internal and external channels. The flame field generated by the central duty flame provides a stable high-temperature environment for the decomposition of ammonia fuel, with high combustion stability and NO x Low emissions.

[0047] (3) The combustion power of the burner can be adjusted by adjusting the number of openings of the fuel inlet pipe 9.

[0048] (4) The design of micro-decomposition holes makes the fuel flow rate high, effectively preventing the phenomenon of combustion backfire.

[0049] (5) The primary air duct 4, the burnout air duct 5 and the primary air distribution pipe 10 are tightly connected and separated, so that the fuel and oxidant at each level can be evenly mixed when they reach the burner outlet plane, avoiding the pre-mixing of the fuel and oxidant. According to the required working conditions, the ratio between the fuel and the oxidant can be precisely controlled to achieve rapid decomposition of the ammonia-blended fuel and achieve low NO x Combustion technology.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A multi-stage micro-decomposition swirl burner for ammonia-blended fuel, characterized in that: The invention comprises a natural gas central pipe (1), a primary air pipe (2) and a burner shell (3) which are sequentially sleeved from the inside to the outside, a primary air duct (4) is formed between the outer wall of the natural gas central pipe (1) and the inner wall of the primary air pipe (2), and a burnout air channel (5) is formed between the outer wall of the primary air pipe (2) and the inner wall of the burner shell (3), wherein: An ignition device (6) and a swirl blade (7) are provided in the primary air duct (4). The swirl blade (7) is installed on the outer periphery of the outlet end of the natural gas central pipe (1). The swirl blade (7) is used to mix the primary air in the primary air duct (4) with the natural gas sprayed from the outlet end of the natural gas central pipe (1) in a swirl state. The ignition device (6) is used to ignite the mixed primary air and natural gas to form a duty flame with sustainable combustion at the outlet end of the natural gas central pipe (1); A fuel distribution nozzle (8) is arranged in the burnout air channel (5). The fuel distribution nozzle (8) is arranged close to the outlet end of the natural gas central pipe (1). The outlet end of the fuel distribution nozzle (8) is provided with a plurality of micro-decomposition holes (81) to eject the ammonia-blended fuel at high speed, so that the ammonia in the ammonia-blended fuel burns under the action of the on-duty flame, and when the ammonia-blended fuel is ejected at high speed, a negative pressure is formed at the port of the burnout air channel (5), thereby sucking in the burnout air formed by the combustion of the ammonia-blended fuel.

2. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to claim 1 is characterized in that: The outer wall of the primary air duct (2) is also provided with a primary air distribution pipe (10) connected to the primary air channel (4); the primary air distribution pipe (10) is located in the burnout air channel (5); the outlet end of the primary air distribution pipe (10) is located at the periphery of the outlet end of the primary air duct (2); and the outlet end of the primary air distribution pipe (10) is longer than the outlet ends of the natural gas central pipe (1) and the primary air duct (2).

3. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to claim 2 is characterized in that: The outlet end of the primary air distribution pipe (10) is provided with a distribution pipe nozzle, and the axial angle between the distribution pipe nozzle and the primary air pipe (2) is adjustable.

4. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to claim 2 or 3, characterized in that: The outer wall of the primary air duct (2) is provided with a plurality of primary air distribution pipes (10) evenly distributed along its circumference.

5. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to any one of claims 1 to 3, characterized in that: A plurality of the fuel distribution nozzles (8) are arranged in the burnout air channel (5), and all of the fuel distribution nozzles (8) are evenly distributed around the circumference of the primary air duct (2); the micro-decomposition holes (81) in any of the fuel distribution nozzles (8) are evenly distributed.

6. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to any one of claims 1 to 3, characterized in that: The ignition device (6) is an ignition gun.

7. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to any one of claims 1 to 3, characterized in that: The swirl blades (7) include a plurality of circumferentially spaced swirl blades, and the axial angle between any one of the swirl blades and the primary air duct (2) is 30° to 45°.

8. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to any one of claims 1 to 3, characterized in that: The diameter of any one of the micro-decomposition holes (81) is 3 mm to 7 mm.

9. A low NO x The control method is implemented by using the ammonia-blended fuel multi-stage micro-decomposition swirl burner as claimed in any one of claims 1 to 8, characterized in that: include: The portion of the natural gas accounting for 20% by volume is ejected through the outlet end of the natural gas central pipe (1), and is mixed with the primary air and burned to form the on-duty flame under the action of the ignition device (6); An ammonia-blended fuel is formed by premixing 80% of the volume of natural gas with ammonia at a preset equivalence ratio and then injected into the flame zone formed by the on-duty flame through the fuel distribution nozzle (8), so that the ammonia in the ammonia-blended fuel burns and decomposes under the action of the on-duty flame.

10. Low NO according to claim 9 x The control method is characterized in that During the combustion of the ammonia-blended fuel, the overall equivalence ratio of the ammonia-blended fuel to the ammonia-blended fuel multi-stage differential decomposition swirl burner is controlled in a lean combustion state, and the local equivalence ratio of the burnout air to the ammonia-blended fuel is controlled in a rich combustion state.

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