An ammonia-doped multi-stage micro-dissociation swirl burner and low-NO x Control method

Abstract

The application discloses a multi-stage micro-decomposition cyclone burner for ammonia-doped fuel and low-NO x The control method, the natural gas center pipe, the primary air pipe and the burner shell are sequentially nested from inside to outside, forming a primary air channel and a burnout air passage which are isolated from each other, natural gas is sprayed out from the natural gas center pipe, the cyclone blade is arranged in the primary air channel, the primary air can be mixed with the central natural gas in a cyclone state, then a diffusion flame is formed under the action of an ignition device, in this way, a duty flame which can be continuously combusted is formed in the center of the spraying end of the burner; ammonia gas is premixed with natural gas to form ammonia-doped fuel, and the ammonia-doped fuel is sprayed out at a high speed through micro-decomposition holes to form a negative pressure which continuously sucks the surrounding burnout air, meanwhile, the ammonia-doped fuel is sprayed into the high-temperature combustion area of the duty flame in the center of the burner, so that the ammonia is rapidly decomposed, and a large amount of hydrogen gas generated by the ammonia is helpful to improve the combustion stability. The application has novel and reasonable structure arrangement, can improve the combustion stability, reduce the NO x emission and has the advantages of low cost, high efficiency, high safety and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of combustion equipment, and relates to a burner for combusting gaseous fuel, in particular to a multi-stage micro-decomposition swirl burner for combusting ammonia-doped fuel and a low-NO x Control method. BACKGROUND

[0002] In the combustion of a premixing type swirl burner, the mixing ratio and mixing uniformity of ammonia-doped fuel and oxidant directly determine the NO x emission effect of the burner. The existing swirl burner cannot meet the current safety and environmental protection requirements of the burner due to the insufficient mixing of ammonia-doped fuel and oxidant, the unsatisfactory flame effect, and the high emission of nitrogen oxides. SUMMARY

[0003] The present application aims to provide a multi-stage micro-decomposition swirl burner for combusting ammonia-doped fuel and a low-NO x control method, which has high combustion stability and low NO x emission, so as to solve the problems of the existing burner, such as the insufficient mixing of ammonia-doped fuel and oxidant, the unsatisfactory flame effect, and the high emission of nitrogen oxides.

[0004] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0005] The present application provides a multi-stage micro-decomposition swirl burner for combusting ammonia-doped fuel, which comprises a natural gas center pipe, a primary air pipe and a burner shell which are sequentially sleeved from inside to outside, a primary air duct is formed between the outer wall of the natural gas center pipe and the inner wall of the primary air pipe, and a burnout air passage is formed between the outer wall of the primary air pipe and the inner wall of the burner shell, wherein:

[0006] A ignition device and a swirl vane are arranged in the primary air duct, the swirl vane is installed on the outer periphery of the outlet end of the natural gas center pipe, the swirl vane is used to mix the primary air in the primary air duct with the natural gas sprayed from the outlet end of the natural gas center pipe in a swirl state, and the ignition device is used to ignite the mixed primary air and natural gas to form a duty flame which can be continuously combusted at the outlet end of the natural gas center pipe;

[0007] A fuel distribution nozzle is arranged in the burnout air passage, the fuel distribution nozzle is arranged close to the outlet end of the natural gas center pipe, a plurality of micro-decomposition holes are arranged at the outlet end of the fuel distribution nozzle, the ammonia-doped fuel is sprayed at a high speed through the micro-decomposition holes, the ammonia in the ammonia-doped fuel is combusted under the action of the duty flame, a negative pressure is formed at the port of the burnout air passage when the ammonia-doped fuel is sprayed at a high speed, and the burnout air formed by the combustion of the ammonia-doped fuel is sucked.

[0008] Optionally, the outer wall of the primary air pipe is further provided with a primary air distribution pipe in communication with the primary air duct, the primary air distribution pipe is located in the overfire air passage, the outlet end of the primary air distribution pipe is located at the outer periphery of the outlet end of the primary air pipe, and the outlet end of the primary air distribution pipe is longer than the outlet end of the natural gas center pipe and the primary air pipe.

[0009] Optionally, the outlet end of the primary air distribution pipe is provided with a distribution pipe nozzle, and the axial angle between the distribution pipe nozzle and the primary air pipe is adjustable.

[0010] Optionally, the outer wall of the primary air pipe is uniformly distributed with a plurality of primary air distribution pipes along the circumference thereof.

[0011] Optionally, a plurality of fuel distribution nozzles are arranged in the overfire air passage, and all the fuel distribution nozzles are uniformly distributed around the circumference of the primary air pipe; the micro-decomposition holes in any one of the fuel distribution nozzles are uniformly distributed.

[0012] Optionally, the ignition device is an ignition gun.

[0013] Optionally, the swirler vane includes a plurality of circumferentially spaced swirler vanes, and the axial angle between any one of the swirler vanes and the primary air pipe is 30°-45°.

[0014] Optionally, the diameter of any one of the micro-decomposition holes is 3mm-7mm.

[0015] The application further provides a low-NOx x The control method is implemented by using the ammonia-doped fuel multi-stage micro-decomposition swirler burner according to any one of the above, and includes: discharging 20% of the natural gas by volume through the outlet end of the natural gas center pipe, and mixing and burning with primary air under the action of the ignition device to form the duty flame; discharging the ammonia-doped fuel formed by premixing 80% of the natural gas by volume with ammonia gas through the fuel distribution nozzle into the flame zone formed by the duty flame after premixing at a preset equivalence ratio, so that the ammonia in the ammonia-doped fuel is burned and decomposed under the action of the duty flame.

[0016] Optionally, during the ammonia-doped fuel combustion process, the overall equivalence ratio of the ammonia-doped fuel and the ammonia-doped fuel multi-stage micro-decomposition swirler burner is controlled in a lean combustion state, and the local equivalence ratio of the overfire air and the ammonia-doped fuel is controlled in a rich combustion state.

[0017] Optionally, during the ammonia-doped fuel combustion process, the overall equivalence ratio of the ammonia-doped fuel and the ammonia-doped fuel multi-stage micro-decomposition swirler burner is controlled to be 0.7-0.8, and the local equivalence ratio of the overfire air and the ammonia-doped fuel is controlled to be 1.05-1.3.

[0018] The present application has the following technical effects relative to the prior art:

[0019] The ammonia-doped fuel multi-stage micro-decomposition swirl burner disclosed by the present application is formed by stacking the natural gas center pipe, the primary air pipe and the burner shell from inside to outside, thereby forming a primary air channel and a combustion air passage that are isolated from each other. The natural gas is sprayed out from the natural gas center pipe, the swirl vanes are arranged in the primary air channel and located around the natural gas center pipe, so that the primary air is mixed with the center natural gas in a swirl state, and then forms a diffusion flame under the action of the ignition device. In this way, the center of the spray end of the ammonia-doped fuel multi-stage micro-decomposition swirl burner forms a duty flame that can be continuously combusted. The ammonia gas is premixed with the natural gas to form ammonia-doped fuel, which is sprayed out at a high speed through the micro-decomposition holes, thereby continuously absorbing the surrounding combustion air under negative pressure. At the same time, the ammonia-doped fuel sprayed into the high-temperature combustion area of the duty flame in the center of the burner causes the ammonia to be rapidly decomposed, and a large amount of hydrogen gas generated thereby helps to improve the combustion stability. The ammonia-doped fuel multi-stage micro-decomposition swirl burner has a novel and reasonable structure arrangement, can improve the combustion stability, reduce the NO x emission, and has the advantages of high efficiency, low pollution, etc.

[0020] In some technical solutions disclosed by the present application, the primary air distribution pipe with adjustable spray head angle is arranged outside the primary air pipe, and the outlet end of the primary air distribution pipe is longer than the outlet ends of the natural gas center pipe and the primary air pipe, so that part of the primary air is delayed to enter the combustion area, thereby ensuring the complete combustion of the fuel and further improving the combustion stability. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0022] Fig. 1 The structure diagram of the ammonia-doped fuel multi-stage micro-decomposition swirl burner disclosed by the present application;

[0023] Fig. 2 The front view of the ammonia-doped fuel multi-stage micro-decomposition swirl burner disclosed by the present application;

[0024] Fig. 3 The side view of the ammonia-doped fuel multi-stage micro-decomposition swirl burner disclosed by the present application.

[0025] Among them, the reference signs are:

[0026] 100, ammonia-doped fuel multi-stage micro-decomposition swirl burner;

[0027] 1, natural gas center tube; 2, primary air tube; 3, burner shell; 4, primary air duct; 5, overfire air passage; 6, ignition device; 7, swirl vane; 8, fuel distribution nozzle; 81, micro-decomposition hole; 9, fuel inlet pipe; 10, primary air distribution pipe; 11, bluff body. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] One of the purposes of the present application is to provide a multi-stage micro-decomposition swirl burner for ammonia-doped fuel, which has high combustion stability, low NO x emission, so as to solve the problems of insufficient mixing of ammonia-doped fuel and oxidant, non-ideal flame effect, and high nitrogen oxide emission existing in the prior art.

[0030] Another purpose of the present application is to provide a low-NO x x emission combustion control method based on the above multi-stage micro-decomposition swirl burner for ammonia-doped fuel, which has high combustion stability, low NO x emission, so as to solve the problems of insufficient mixing of ammonia-doped fuel and oxidant, non-ideal flame effect, and high nitrogen oxide emission existing in the prior art.

[0031] In order to make the above purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0032] Embodiment 1

[0033] As Figs. 1-3As shown, the embodiment provides a multi-stage micro-decomposition swirl burner 100 for ammonia-doped fuel, which comprises a natural gas center pipe 1, a primary air pipe 2 and a burner shell 3, which are sequentially sleeved from inside to outside, a primary air channel 4 is formed between the outer wall of the natural gas center pipe 1 and the inner wall of the primary air pipe 2, and a combustion air passage 5 is formed between the outer wall of the primary air pipe 2 and the inner wall of the burner shell 3, wherein the primary air channel 4 is provided with an ignition device 6 and a swirl vane 7, the swirl vane 7 is installed on the outer periphery of the outlet end of the natural gas center pipe 1, the swirl vane 7 is used to mix the primary air in the primary air channel 4 with the natural gas sprayed from the outlet end of the natural gas center pipe 1 in a swirl state, the ignition device 6 is used to ignite the mixed primary air and natural gas to form a sustained duty flame at the outlet end of the natural gas center pipe 1; the combustion air passage 5 is provided with a fuel distribution nozzle 8, the fuel distribution nozzle 8 is arranged close to the outlet end of the natural gas center pipe 1, and the outlet end of the fuel distribution nozzle 8 is provided with a plurality of micro-decomposition holes 81 to spray the ammonia-doped fuel at a high speed, so that the ammonia in the ammonia-doped fuel is burned under the action of the duty flame, and a negative pressure is formed at the port of the combustion air passage 5 when the ammonia-doped fuel is sprayed at a high speed, thereby sucking the combustion air formed by the burning of the ammonia-doped fuel.

[0034] In the embodiment, the outer wall of the primary air pipe 2 is further provided with a primary air distribution pipe 10 which is in communication with the primary air channel 4, the primary air distribution pipe 10 is located in the combustion air passage 5, the outlet end of the primary air distribution pipe 10 is located on the outer periphery of the outlet end of 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 center pipe 1 and the primary air pipe 2, so that the primary air sprayed through the primary air distribution pipe 10 is delayed to enter the combustion area compared with the primary air sprayed through the primary air pipe 2, thereby ensuring sufficient combustion of the fuel.

[0035] In the embodiment, 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, and the adjustment angle is generally-45°-45°. For the adjustment of the angle 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 a nozzle can be installed by using an existing spray angle adjustment structure to adjust the axial angle between the distribution pipe nozzle and the primary air pipe 2, and the spray angle adjustment structure can be a universal valve, a universal adjuster, a structure disclosed in patent CN101121157A, etc.

[0036] In the embodiment, the total ratio of the air flow rate to the primary air through any one primary air distribution pipe 10 is the ratio of the cross-sectional area of the primary air distribution pipe 10 to the cross-sectional area of the primary air pipe 2.

[0037] In this embodiment, the outer wall of the primary air pipe 2 is uniformly distributed with a plurality of primary air distribution pipes 10 along the circumference thereof.

[0038] In this embodiment, a plurality of fuel distribution nozzles 8 are arranged in the overfire air passage 5, and all the fuel distribution nozzles 8 are uniformly distributed around the circumference of the primary air pipe 2; the micro-decomposition holes 81 in any fuel distribution nozzle 8 are uniformly distributed, which can make the outlet flow field of the burner uniformly distributed. As a further preferred solution, the fuel distribution nozzles 8 are distributed on the outer periphery of the plurality of primary air distribution pipes 10, as shown in Fig. 1 and Fig. 2 The outlet end of the primary air distribution pipe 10 is longer than the outlet end of the fuel distribution nozzle 8.

[0039] In this embodiment, any fuel distribution nozzle 8 is also connected with a fuel inlet pipe 9. The fuel inlet pipes 9 connected on all the fuel distribution nozzles 8 are preferably equal in diameter and parallel to each other with uniform spacing. The load of the ammonia-doped fuel multi-stage micro-decomposition swirl burner 100 can be adjusted by the number of fuel inlet pipes 9 opened.

[0040] In this embodiment, the ignition device 6 is preferably an ignition gun. The ignition gun can be used as an air inlet passage for other fuels after completing ignition.

[0041] In this embodiment, the swirl vane 7 includes a plurality of circumferentially spaced swirl vanes, and the included angle between any swirl vane and the axis of the primary air pipe 2 is 30°-45°.

[0042] In this embodiment, the diameter of any micro-decomposition hole 81 is 3mm-7mm. Further, the diameter of any micro-decomposition hole 81 can be specifically 3mm, 5mm or 7mm.

[0043] In this embodiment, the natural gas center pipe 1 is a whole elbow structure, one end of which is located in the primary air pipe 2 and arranged coaxially with the primary air pipe 2, and the other end penetrates the side wall of the primary air pipe 2 and extends to the outside of the primary air pipe 2, as shown in Figs. 1-3 This structure arrangement facilitates the ventilation of the natural gas center pipe 1 and the primary air pipe 2 at the same time, avoiding interference between the two when ventilating at the same time. The inner wall of the outlet end of the natural gas center pipe 1 is arranged in the shape of a blunt body 11 to conform to the blunt body aerodynamics. The arrangement of the blunt body 11 is a conventional technical means in the field of burners, which will not be described here.

[0044] The above-mentioned ammonia-doped multi-stage micro-decomposition swirl burner 100 is sequentially nested from inside to outside by the natural gas central pipe 1, the primary air pipe 2 and the burner shell 3, forming a primary air channel 4 and a combustion air passage 5 which are isolated from each other. The natural gas is sprayed from the natural gas central pipe 1, and the volume ratio of this part of natural gas is about 20%. The swirl vanes 7 are arranged in the primary air channel 4 and located around the natural gas central pipe 1, so that the primary air can be mixed with the central natural gas in a swirling state, and then form a diffusion flame under the action of the ignition device 6. In this way, the center of the spray end of the ammonia-doped multi-stage micro-decomposition swirl burner 100 forms a duty flame that can be continuously burned. The primary air distribution pipe 10 with adjustable spray 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, so that part of the primary air can be delayed into the combustion area to ensure the complete combustion of the fuel. A plurality of fuel distribution nozzles 8 composed of a plurality of micro-decomposition holes 81 are arranged on the outer periphery of the primary air distribution pipe 10. After 100% ammonia gas and the remaining 80% natural gas are premixed to form ammonia-doped fuel, the ammonia-doped fuel is rectified by the fuel inlet pipe 9 connected to the fuel distribution nozzle 8 and then sprayed out of the micro-decomposition hole 81 at high speed, forming a negative pressure that continuously sucks the surrounding combustion air. At the same time, the ammonia-doped fuel is sprayed into the high-temperature combustion area of the duty flame in the center of the burner, so that the ammonia is rapidly decomposed, and a large amount of hydrogen gas is produced to help improve the combustion stability. During the ammonia-doped fuel combustion process, the overall equivalence ratio of the ammonia-doped fuel and the ammonia-doped multi-stage micro-decomposition swirl burner 100 is generally controlled in a lean combustion state, for example, the overall equivalence ratio of the ammonia-doped fuel and the ammonia-doped multi-stage micro-decomposition swirl burner 100 is controlled at 0.7-0.8, and the local equivalence ratio of the combustion air and the ammonia-doped fuel is controlled in a rich combustion state, for example, the local equivalence ratio of the combustion air and the ammonia-doped fuel is controlled at 1.0-1.3. As a further preferred solution, the local equivalence ratio of the combustion air and the ammonia-doped fuel is generally controlled at about 1.2 during the ammonia-doped fuel combustion process.

[0045] As can be seen, the ammonia-doped multi-stage micro-decomposition swirl burner 100 proposed by the technical solution can form a stable high-temperature duty flame in the center part by the central natural gas and the swirling air under the action of the ignition device 6 during operation. The remaining natural gas and ammonia gas are premixed and injected into the high-temperature zone formed by the high-temperature duty flame combustion through the micro-decomposition hole 81 at a certain equivalence ratio. In combination with the arrangement of the primary air distribution pipe, the combustion stability can be improved on the basis of realizing fuel combustion, and the NO x emission can be reduced. Compared with the prior art, the technical solution mainly has the following beneficial technical effects:

[0046] (1) The ammonia-doped multi-stage micro-decomposition swirl burner can realize the precise control of NO x X and can solve the problem of high NO x X emission of the current ammonia-doped fuel.

[0047] (ii) The flame area of the burner is composed of inner and outer channels when burning, and the flame field generated by the center standing flame provides a stable high-temperature environment for the decomposition of ammonia fuel, with high combustion stability, low NO x emission.

[0048] (iii) The combustion power of the burner can be adjusted by adjusting the number of open fuel inlet pipes 9.

[0049] (iv) The design of the micro-decomposition hole makes the fuel flow rate high, effectively preventing the phenomenon of combustion backfire.

[0050] (v) The primary air duct 4, the combustion air channel 5, and the primary air distribution pipe 10 are connected and divided airtight, which can make each level of fuel and oxidant reach a uniform mixing state when reaching the outlet plane position of the burner, avoiding the pre-mixing of fuel and oxidant, and can achieve rapid decomposition of ammonia-doped fuel, low NO x combustion technology according to the required working condition by precisely controlling the ratio between fuel and oxidant.

[0051] The above only describes the preferred embodiments 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 shall be included in the protection scope of the present application.

Claims

1. A multi-stage micro-decomposition swirl burner for ammonia-blended fuel, characterized in that, The system includes a natural gas central pipe (1), a primary air pipe (2), and a burner housing (3) arranged sequentially from the inside out. 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). A burnout air duct (5) is formed between the outer wall of the primary air pipe (2) and the inner wall of the burner housing (3). An ignition device (6) and a swirl vane (7) are installed in the primary air duct (4). The swirl vane (7) is installed on the outer periphery of the outlet end of the natural gas central pipe (1). The swirl vane (7) is used to mix the primary air in the primary air duct (4) with the natural gas injected at the outlet end of the natural gas central pipe (1) in a swirling state. The ignition device (6) is used to ignite the mixed primary air and natural gas to form a continuously burning standby flame at the outlet end of the natural gas central pipe (1). A fuel distribution nozzle (8) is provided in the burnout air channel (5). The fuel distribution nozzle (8) is located near the outlet end of the natural gas center pipe (1). The outlet end of the fuel distribution nozzle (8) is provided with several 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 duty flame. When the ammonia-blended fuel is ejected at high speed, a negative pressure is formed at the port of the burnout air channel (5), which entrains the burnout air formed by the combustion of the ammonia-blended fuel.

2. The ammonia-blended fuel multi-stage micro-decomposition cyclone burner according to claim 1, characterized in that, The outer wall of the primary air duct (2) is also provided with a primary air distribution pipe (10) that communicates with the primary air passage (4). The primary air distribution pipe (10) is located inside the burnout air passage (5). The outlet end of the primary air distribution pipe (10) is located on the outer 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 end of the natural gas center pipe (1) and the primary air duct (2).

3. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to claim 2, 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, Multiple primary air distribution pipes (10) are evenly distributed along the circumference of the outer wall of the primary air duct (2).

5. The ammonia-blended fuel multi-stage micro-decomposition swirl burner according to any one of claims 1 to 3, characterized in that, The burnout air channel (5) is provided with a plurality of fuel distribution nozzles (8), and all the fuel distribution nozzles (8) are evenly distributed around the circumference of the primary air duct (2); the micro-decomposition holes (81) in any fuel distribution nozzle (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 blade (7) includes several circumferentially spaced blades, and the axial angle between any one of the blades and the primary air duct (2) is 30°~45°.

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

9. A low NOx control method, implemented using an ammonia-blended fuel multi-stage micro-decomposition swirl burner as described in any one of claims 1 to 8, characterized in that, include: A portion of natural gas, accounting for 20% of its volume, is ejected through the outlet end of the natural gas central pipe (1) and mixed with primary air under the action of the ignition device (6) to form the duty flame; Ammonia-blended fuel, which is 80% of the volume of natural gas, is premixed with ammonia to form an ammonia-blended fuel. After being premixed at a preset equivalent ratio, the fuel is injected into the flame zone formed by the duty flame through the fuel distribution nozzle (8), so that the ammonia in the ammonia-blended fuel is burned and decomposed under the action of the duty flame.

10. The low NOx control method according to claim 9, 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 micro-decomposition swirl burner is controlled in a lean combustion state, while the local equivalence ratio of the burnout air to the ammonia-blended fuel is controlled in a rich combustion state.

Images