Novel non-premixed natural gas ammonia-doped burner

Abstract

The invention discloses a novel non-premixed natural gas ammonia-doped combustor, and aims to realize efficient mixing of fuel gas and air in the natural gas ammonia-doped combustor, reduce the emission intensity of carbon dioxide and nitrogen oxide, and solve the problems of poor ammonia-doped combustion stability of natural gas, large potential safety hazard of the combustor and the like. The device comprises an ammonia gas nozzle, a swirler, a natural gas nozzle, a secondary air nozzle and a nozzle baffle, and the ammonia gas nozzle, the natural gas nozzle and the secondary air nozzle are sequentially arranged from inside to outside and are concentrically arranged in a surrounding mode; the swirler is positioned between the ammonia gas nozzle and the natural gas nozzle; the nozzle baffle is located between the natural gas nozzle and the secondary air nozzle. The fuel mixing efficiency is enhanced through the swirler, the heat load of a combustion high-temperature area is reduced through secondary air, the combustion delay characteristic of ammonia fuel is improved in combination with the flue gas backflow technology, and a novel combustion technology system with the synergistic effect of the swirler and secondary air flue gas backflow is constructed. The invention relates to the technical field of combustion equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion equipment, and in particular to a novel non-premixed natural gas ammonia-blended burner. Background Art

[0002] With the in-depth promotion of the "dual carbon" strategy, clean energy substitution technology has become an important development direction in the industrial combustion field. The natural gas ammonia-blended combustion technology has attracted much attention due to its low cost and fuel flexibility. As a hydrogen-rich carrier, ammonia has the advantages of high energy density and low storage and transportation costs, and can achieve a smooth transition from fossil energy to a hydrogen economy. However, traditional natural gas ammonia-blended burners face two major technical bottlenecks in practical applications: one is that ammonia itself has a slow flame speed and a large ignition delay. If the mixing degree is insufficient after being mixed with natural gas, it will cause a significant reduction in the flame propagation speed and deterioration of combustion stability; the other is that the formation mechanism of nitrogen oxides (NOx) during the combustion process is complex, and it is difficult to jointly control fuel-type and thermal-type nitrogen oxides, resulting in emission indicators that are difficult to meet environmental protection requirements. In the prior art, staged combustion, premixed combustion and other methods are generally used to improve combustion performance.

[0003] For example, the publication number CN117588753A discloses an ammonia-blended fuel multi-stage micro-decomposition swirl burner and a low-NOx control method; a premixed burner is adopted, and after ammonia and methane are premixed, they are divided into multiple jets and sprayed in to create multiple small-scale flames, reducing the generation of NOx on the flame surface, and at the same time combining a fuel-rich environment to further reduce NOx. Although the premixed combustion technology can improve the fuel mixing uniformity, the premixed gas cannot achieve flue gas recirculation and reburning, and there is a high safety risk of flashback. Moreover, the premixed fuel is sprayed through micro-decomposition holes, and uneven mixing may occur due to local flow velocity differences;

[0004] In addition, although a conventional swirl burner can enhance mixing, its single-stage non-premixed structure still has problems such as insufficient jet stiffness and low mixing efficiency, resulting in a concentrated high-temperature combustion zone and a high NOx generation amount.

[0005] In view of the above problems, the industry has actively explored in the optimization of burner structures in recent years. Some improvement schemes improve the mixing effect by increasing the number of swirl vanes or changing the fuel injection angle, but do not fully consider the entrainment and reburning effect of secondary air on high-temperature flue gas; other studies use multi-stage fuel injection technology to disperse the combustion intensity, but increase the structural complexity. In terms of emission control, the prior art mostly relies on post-treatment means such as selective catalytic reduction (SCR), and fails to achieve the co-suppression of NOx from the combustion source. Therefore, developing a natural gas ammonia-blended burner with a simple structure, high mixing efficiency and capable of achieving source control of pollutants has become the key breakthrough point for promoting the large-scale application of this technology. Summary of the Invention

[0006] The present invention aims to achieve efficient mixing of fuel gas and air in a natural gas ammonia burner, reduce the emission intensity of carbon dioxide and nitrogen oxides, solve the problems of poor combustion stability of natural gas ammonia burner and great safety hazards of burners, and further proposes a novel non-premixed natural gas ammonia burner.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] The present invention comprises an ammonia nozzle, a swirler, a natural gas nozzle, a secondary air nozzle and a nozzle baffle, wherein the ammonia nozzle is located at the center; the natural gas nozzle surrounds the outside of the ammonia nozzle; the secondary air nozzle surrounds the outside of the natural gas nozzle; the ammonia nozzle, the natural gas nozzle and the secondary air nozzle are arranged concentrically; the swirler is located between the ammonia nozzle and the natural gas nozzle; and the nozzle baffle is located between the natural gas nozzle and the secondary air nozzle.

[0009] Furthermore, a smoke reflow channel is provided at the periphery of the secondary air nozzle.

[0010] Furthermore, the multiple blades of the cyclone are evenly distributed in the circumferential direction, and the inclination angle of each blade is 60°; the number of blades is 6-12.

[0011] Furthermore, the secondary air nozzles are evenly distributed along the circumference of the burner, with a number of 8-12 and a tapered inlet.

[0012] Furthermore, the top of the ammonia nozzle is a gradually narrowing frustum, and a plurality of nozzles are evenly distributed on the inclined surface of the frustum along the circumferential direction, and the angle between the inclined surface and the axial direction is 45°.

[0013] Furthermore, the natural gas nozzles are arranged in a circular array, with a number of 6-8.

[0014] Furthermore, a plurality of nozzles are provided on the top of each natural gas nozzle, and the plurality of nozzles are arranged in sequence in a circular array from outside to inside.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention enhances fuel mixing efficiency through a cyclone, uses secondary air to reduce the heat load in the high-temperature combustion zone, combines flue gas recirculation technology to improve the ignition delay characteristics of ammonia fuel, and constructs a new combustion technology system with cyclone and secondary air and flue gas recirculation working in synergy.

[0017] 2. The present invention improves the mixing effect of ammonia, natural gas and air and optimizes the flame shape through the coordinated configuration of the ammonia fuel nozzle, swirler and baffle. The same-side integrated secondary air inlet system simplifies the installation process while ensuring the integrity of the burner structure.

[0018] 3. The co-directional injection strategy of the secondary air and the main fuel in the present invention reduces the area of the high-temperature zone and inhibits the formation of thermal-type nitrogen oxides.

[0019] 4. By arranging a flue gas recirculation channel around the secondary air in the present invention, high-temperature flue gas is entrained to the flame initiation section for recirculation and mixing, which improves the flame propagation speed of ammonia and enhances combustion stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a combustion system diagram of the present invention;

[0021] Figure 2 It is a schematic structural diagram of the burner of the present invention;

[0022] Figure 3 It is a schematic structural diagram of the natural gas nozzle of the present invention;

[0023] Figure 4 It is a schematic structural diagram of the ammonia nozzle of the present invention;

[0024] Figure 5 It is a schematic structural diagram of the swirler of the present invention;

[0025] Figure 6 It is a schematic diagram of the blade arrangement mode of the swirler of the present invention;

[0026] Figure 7 It is a schematic diagram of the working mode of the baffle of the present invention.

[0027] In the figure:

[0028] 1. Ammonia nozzle; 1-1. Ammonia injection port;

[0029] 2. Swirler;

[0030] 3. Natural gas nozzle; 3-1. Natural gas injection port;

[0031] 4. Secondary air nozzle;

[0032] 5. Nozzle baffle. DETAILED DESCRIPTION OF THE INVENTION

[0033] DETAILED DESCRIPTION OF THE INVENTION I: As Figure 2 shown, a novel non-premixed natural gas-ammonia co-firing burner described in this embodiment includes an ammonia nozzle 1, a swirler 2, a natural gas nozzle 3, and a secondary air nozzle 4. The ammonia nozzle 1 is located at the central position, the natural gas nozzle 3 surrounds the ammonia nozzle 1, the secondary air nozzle 4 surrounds the natural gas nozzle 3, and the ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged concentrically in a surrounding manner; the swirler 2 is located between the ammonia nozzle 1 and the natural gas nozzle 3.

[0034] AsFigures 5-6 As shown, a plurality of vanes of the cyclone 2 are circumferentially and uniformly arranged, and the inclination angle of each vane is 60°; the number of vanes is 6 - 12. It is used to enhance the radial and axial mixing efficiency of fuel and air.

[0035] As Figure 2 shown, the secondary air nozzles 4 are uniformly distributed along the circumference of the burner, and the number is 8. The inlet of the secondary air is necked down to increase the jet stiffness of the secondary air. After entering the combustion zone, it reaches the top of the flame and undergoes recirculation, generating a stable vortex, and entraining high-temperature flue gas back to the flame root, transferring heat to the unburned ammonia, increasing the flame speed of ammonia, and improving combustion stability.

[0036] As Figure 4 shown, the top of the ammonia nozzle 1 is a frustum cone that gradually converges in sequence. A plurality of ammonia nozzles 1 - 1 are circumferentially and uniformly arranged on the inclined surface of the frustum cone. The included angle between its inclined surface and the axial direction is 45°. The number of ammonia nozzles 1 - 1 is 8. Each ammonia nozzle 1 - 1 is a small hole with an axial angle of 45°; the jet direction of the ammonia nozzle 1 is the same as the swirl direction of the cyclone 2. In this burner, ammonia is sprayed into the surroundings at a 45° angle from the central inlet, and is quickly mixed with the swirling air and methane.

[0037] As Figure 3 shown, the natural gas nozzles 3 are arranged in an annular array, and the number is 8. A plurality of natural gas nozzles 3 - 1 are provided at the top of each natural gas nozzle 3. The plurality of natural gas nozzles 3 - 1 are arranged in an annular array from the outside to the inside in sequence, and the structure of the nozzles 3 - 1 adopts a dense arrangement.

[0038] The present invention enhances the axial and radial mixing efficiency of fuel and air by reconstructing the layout of the secondary air inlet of the burner and the synergy mechanism of creating a strong recirculation zone in the combustion zone, forms a stable recirculation zone to extend the flue gas entrainment path, and reduces the range of the local high-temperature zone. The optimized burner utilizes the secondary air to entrain high-temperature flue gas back to the flame root to improve the ignition delay characteristics of ammonia, combines the regulation of jet velocity to achieve the reconstruction of the flame structure, and suppresses pollutant generation through the dynamic equilibrium mechanism of thermal and fuel-type NOx, ultimately achieving the goals of improving combustion stability and synergistic emission reduction of carbon emissions and nitrogen oxides.

[0039] Specific Embodiment 2: As Figure 2 、 Figure 7As shown in the figure, a novel non-premixed natural gas ammonia-blended burner described in this embodiment includes an ammonia nozzle 1, a swirler 2, a natural gas nozzle 3, a secondary air nozzle 4, and a nozzle baffle 5. The ammonia nozzle 1 is located at the central position, the natural gas nozzle 3 surrounds the ammonia nozzle 1 on the outside, the secondary air nozzle 4 surrounds the natural gas nozzle 3 on the outside, and the ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged in concentric circles; the swirler 2 is located between the ammonia nozzle 1 and the natural gas nozzle 3. The nozzle baffle 5 is located between the natural gas nozzle 3 and the secondary air nozzle 4. The nozzle baffle 5 is an annular baffle, which is used to adjust the mixing path of natural gas and secondary air, avoid flame flashback, optimize the combustion temperature distribution, and reduce NOx generation.

[0040] Specific Embodiment 3: As Figure 2 As shown in the figure, a novel non-premixed natural gas ammonia-blended burner described in this embodiment includes an ammonia nozzle 1, a swirler 2, a natural gas nozzle 3, a secondary air nozzle 4, a nozzle baffle 5, and a flue gas recirculation channel. The ammonia nozzle 1 is located at the central position, the natural gas nozzle 3 surrounds the ammonia nozzle 1 on the outside, the secondary air nozzle 4 surrounds the natural gas nozzle 3 on the outside, and the ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged in concentric circles; the swirler 2 is located between the ammonia nozzle 1 and the natural gas nozzle 3. The nozzle baffle 5 is located between the natural gas nozzle 3 and the secondary air nozzle 4. Due to the injection of secondary air, the air pressure at the wall surface of the combustion chamber cavity decreases, and part of the high-temperature flue gas will form a backflow at the wall surface. The backflow of the high-temperature flue gas raises the air temperature and accelerates the ignition of the fuel gas. The nozzle baffle forms an angle of 15 - 45° with the axial direction of the burner. Its main function is to gather the fuel gas and ensure that the fuel gas mixes and burns with air and high-temperature flue gas after entering the burner for a certain distance, reducing the temperature at the fuel gas nozzle and preventing the fuel gas from burning out the burner nozzle prematurely.

[0041] The above are only preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed with preferred examples as above, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or equivalent changes and modifications within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention and is based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement of the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. A novel non-premixed natural gas-ammonia burner, characterized in that: It includes an ammonia nozzle (1), a swirler (2), a natural gas nozzle (3), a secondary air nozzle (4) and a nozzle baffle (5). The ammonia nozzle (1) is located at the central position. The natural gas nozzle (3) surrounds the ammonia nozzle (1) on the outside. The secondary air nozzle (4) surrounds the natural gas nozzle (3) on the outside. The ammonia nozzle (1), the natural gas nozzle (3) and the secondary air nozzle (4) are arranged concentrically and surroundingly. The swirler (2) is located between the ammonia nozzle (1) and the natural gas nozzle (3). The nozzle baffle (5) is located between the natural gas nozzle (3) and the secondary air nozzle (4).

2. The novel non-premixed natural gas-ammonia burner according to claim 1, characterized in that: A flue gas recirculation channel is provided on the periphery of the secondary air nozzle (4).

3. A novel non-premixed natural gas-ammonia burner according to claim 1, characterized in that: Multiple vanes (2-1) of the swirler (2) are circumferentially and evenly arranged, and the inclination angle of each vane is 60°; the number of vanes (2-1) is 6-12.

4. A novel non-premixed natural gas-ammonia burner according to claim 1, characterized in that: The secondary air nozzles (4) are evenly distributed circumferentially around the burner, and the number is 8-12, and they adopt a reduced-orifice inlet.

5. A novel non-premixed natural gas ammonia-blended burner according to claim 1, characterized in that: The top of the ammonia nozzle (1) is a frustum of a cone that gradually tapers, and multiple nozzles (1-1) are circumferentially and evenly arranged on the inclined surface of the frustum of the cone, and the included angle between the inclined surface and the axis is 45°.

6. A novel non-premixed natural gas ammonia-doped burner according to claim 1, characterized in that: The natural gas nozzles (3) are arranged in an annular array, and the number is 6-8.

7. A novel non-premixed natural gas-ammonia burner according to claim 6, characterized in that: Multiple nozzles (3-1) are provided at the top of each natural gas nozzle (3), and the multiple nozzles (3-1) are arranged in an annular array from outside to inside in sequence.

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