A non-premixed natural gas ammonia blended burner

Abstract

The application discloses a non-premixed natural gas ammonia blending combustor, and aims to realize efficient mixing of fuel gas and air in the natural gas ammonia blending combustor, reduce carbon dioxide and nitrogen oxide emission intensity, and solve problems of poor combustion stability of the natural gas ammonia blending combustor and great safety hidden danger of the combustor, and comprises an ammonia gas nozzle, a cyclone device, a natural gas nozzle, a secondary air nozzle and a nozzle baffle, wherein the ammonia gas nozzle, the natural gas nozzle and the secondary air nozzle are sequentially arranged from inside to outside and are arranged in a concentric ring mode; the cyclone device is located between the ammonia gas nozzle and the natural gas nozzle; and the nozzle baffle is located between the natural gas nozzle and the secondary air nozzle. The application strengthens fuel mixing efficiency through the cyclone device, reduces high-temperature zone thermal load through the secondary air, improves the ammonia fuel slow-burning characteristic by combining with the flue gas backflow technology, and constructs a new combustion technology system with the synergistic effect of the cyclone device and the secondary air flue gas backflow. The application relates to the technical field of combustion equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of combustion equipment, in particular to a non-premixed natural gas ammonia blending burner. BACKGROUND

[0002] Clean energy replacement technology has become an important development direction in the field of industrial combustion. Natural gas ammonia blending combustion technology has attracted much attention due to its low cost and fuel flexibility. Ammonia, as a hydrogen carrier, has the advantages of high energy density and low storage and transportation cost, which can realize the smooth transition from fossil energy to hydrogen energy economy. However, the traditional natural gas ammonia blending burner faces two major technical bottlenecks in practical application: first, ammonia itself has a slow flame speed and a large ignition delay. If the mixing degree is insufficient after mixing with natural gas, the flame propagation speed will be greatly reduced and the combustion stability will be deteriorated. Second, the generation mechanism of nitrogen oxides (NOx) in the combustion process is complex, and it is difficult to control fuel-type and thermal-type nitrogen oxides simultaneously, which makes it difficult to meet environmental protection requirements. The existing technology generally uses staged combustion and premixed combustion to improve combustion performance.

[0003] For example, CN117588753A discloses a multi-stage micro-decomposition cyclone burner for ammonia-blended fuel and a low-NOx control method. A premixed burner is used to create multiple small-scale flames by injecting multiple streams of premixed ammonia and methane, thereby reducing the generation of NOx on the flame surface. The premixed combustion technology can improve the uniformity of fuel mixing, but the premixed gas cannot achieve backflow and reburning of flue gas, which has a high risk of backfire and safety hazards. Moreover, the premixed fuel is injected through micro-decomposition holes, which may result in uneven mixing due to local flow rate differences.

[0004] In addition, although the conventional cyclone burner can enhance mixing, its single-stage non-premixed structure still has problems of insufficient jet stiffness and low mixing efficiency, which leads to the concentration of high-temperature combustion zones and high NOx generation.

[0005] In view of the above problems, the industry has actively explored the optimization of burner structure in recent years. Some improvement schemes increase the number of cyclone vanes or change the fuel injection angle to improve mixing, but do not fully consider the effect of secondary air on the entrainment and reburning of high-temperature flue gas. Another study uses multi-stage fuel injection technology to disperse the combustion intensity, but increases the structural complexity. In terms of emission control, existing technologies rely on end-of-pipe treatment methods such as selective catalytic reduction (SCR), and are unable to achieve simultaneous inhibition of NOx from the source. Therefore, developing a natural gas ammonia blending burner with simple structure, high mixing efficiency, and the ability to control pollutants from the source is a key breakthrough for promoting the large-scale application of this technology. SUMMARY

[0006] The application is to realize efficient mixing of fuel gas and air in the natural gas ammonia burner, reduce the emission intensity of carbon dioxide and nitrogen oxides, solve the problems of poor stability of natural gas ammonia combustion, large safety hidden danger of the burner and the like, and further put forward a non-premixed natural gas ammonia burner.

[0007] The technical scheme adopted by the application to solve the above problems is:

[0008] The application comprises an ammonia gas nozzle, a cyclone, a natural gas nozzle, a secondary air nozzle and a nozzle baffle, the ammonia gas nozzle is located at the center, the natural gas nozzle is arranged outside the ammonia gas nozzle, the secondary air nozzle is arranged outside the natural gas nozzle, the ammonia gas nozzle, the natural gas nozzle and the secondary air nozzle are arranged in a concentric ring, the cyclone is located between the ammonia gas nozzle and the natural gas nozzle, and the nozzle baffle is located between the natural gas nozzle and the secondary air nozzle.

[0009] Further, the secondary air nozzle is provided with a flue gas backflow channel.

[0010] Further, the plurality of blades of the cyclone are circumferentially and uniformly arranged, and the inclination angle of each blade is 60°; and the number of blades is 6-12.

[0011] Further, the secondary air nozzles are uniformly distributed along the circumference of the burner, and the number is 8-12, and a necked inlet is adopted.

[0012] Further, the top of the ammonia gas nozzle is a conical frustum body which is gradually tapered, a plurality of nozzles are circumferentially and uniformly arranged on the inclined surface of the conical frustum body, and the included angle between the inclined surface and the axial direction is 45°.

[0013] Further, the natural gas nozzle is arranged in a ring array, and the number is 6-8.

[0014] Further, the top of each natural gas nozzle is provided with a plurality of nozzles, and the plurality of nozzles are arranged in a ring array from outside to inside.

[0015] The application has the following beneficial effects:

[0016] 1. The application strengthens the fuel mixing efficiency by the cyclone, reduces the high-temperature zone thermal load by the secondary air, improves the ammonia fuel residence characteristics by the flue gas backflow technology, and constructs a new combustion technology system of the cyclone and the secondary air flue gas backflow cooperation.

[0017] 2. The application improves the mixing effect of ammonia gas, natural gas and air by the collaborative configuration of the ammonia fuel nozzle, the cyclone and the baffle, and optimizes the flame shape. The same side integrated secondary air inlet system simplifies the installation process on the basis of ensuring the overall integrity of the burner structure.

[0018] 3. The co-injection strategy of the secondary air and the main fuel in this invention reduces the area of ​​the high-temperature zone and suppresses the generation of thermal nitrogen oxides.

[0019] 4. This invention sets up a flue gas recirculation channel around the secondary air, and recirculates and mixes the high-temperature flue gas to the flame initiation section, thereby increasing the flame propagation speed of ammonia and enhancing combustion stability. Attached Figure Description

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

[0021] Figure 2 This is a schematic diagram of the burner structure of the present invention;

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

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

[0024] Figure 5 This is a schematic diagram of the structure of the hydrocyclone of the present invention;

[0025] Figure 6 This is a schematic diagram of the blade arrangement of the hydrocyclone of the present invention;

[0026] Figure 7 This is a schematic diagram illustrating the working principle of the baffle of the present invention.

[0027] In the picture:

[0028] 1. Ammonia nozzle; 1-1. Ammonia inlet;

[0029] 2. Hydrocyclone;

[0030] 3. Natural gas nozzle; 3-1. Natural gas inlet;

[0031] 4. Secondary air nozzle;

[0032] 5. Nozzle baffle. Detailed Implementation

[0033] Specific implementation method one: as follows Figure 2 As shown, the non-premixed natural gas ammonia-blended burner of 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 center, the natural gas nozzle 3 surrounds the outside of the ammonia nozzle 1, and the secondary air nozzle 4 surrounds the outside of the natural gas nozzle 3. The ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged concentrically. The swirler 2 is located between the ammonia nozzle 1 and the natural gas nozzle 3.

[0034] like Figures 5-6As shown, the plurality of blades of the swirler 2 are circumferentially and uniformly distributed, and the inclination angle of each blade is 60°; the number of blades is 6-12.

[0035] As shown in the figure, Figure 2 As shown, the plurality of secondary air nozzles 4 are uniformly distributed along the circumference of the burner, and the number is 8; the secondary air inlet is subjected to necking treatment to increase the jet stiffness of the secondary air, and after entering the combustion area, the backflow occurs at the top of the flame, a stable vortex is generated, and the high-temperature flue gas is sucked back to the flame root, the heat is transferred to the unburned ammonia gas, the flame speed of the ammonia gas is increased, and the combustion stability is improved.

[0036] As shown in the figure, Figure 4 As shown in the figure, the top of the ammonia gas nozzle 1 is a conical body that gradually narrows in sequence, and a plurality of ammonia gas nozzles 1-1 are circumferentially and uniformly arranged on the inclined surface of the conical body, the included angle between the inclined surface and the axial direction is 45°, and the number of ammonia gas nozzles 1-1 is 8; each ammonia gas nozzle 1-1 is an axial 45° small hole; the spraying direction of the ammonia gas nozzle 1 is consistent with the swirling direction of the swirler 2, and in the burner, the ammonia gas is sprayed at an angle of 45° from the center inlet to the periphery, and is rapidly mixed with the swirling air and methane.

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

[0038] The present application enhances the axial and radial mixing efficiency of fuel and air by reconstructing the secondary air inlet layout of the burner and creating a strong backflow area in the combustion area, forms a stable backflow area to prolong the flue gas suction path, and reduces the range of local high temperature area. After optimization, the burner uses the secondary air to suck the high-temperature flue gas back to the flame root to improve the ammonia gas combustion lagging characteristics, combines with the jet velocity control to realize the flame structure reconstruction, suppresses the generation of pollutants through the dynamic balance mechanism of thermal type and fuel type NOx, and finally achieves the goal of improving the combustion stability and synergistically reducing carbon emissions and nitrogen oxides.

[0039] Specific implementation method two: as Figure 2 , Figure 7As shown, the non-premixed natural gas ammonia burner of the 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 center, the natural gas nozzle 3 is arranged outside the ammonia nozzle 1, the secondary air nozzle 4 is arranged outside the natural gas nozzle 3, and the ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged in a concentric ring. 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 the natural gas and the secondary air, avoid flame backfire, optimize the combustion temperature distribution, and reduce the generation of NOx.

[0040] Specific embodiment three: as Figure 2 As shown, the non-premixed natural gas ammonia burner of the 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 backflow channel. The ammonia nozzle 1 is located at the center, the natural gas nozzle 3 is arranged outside the ammonia nozzle 1, the secondary air nozzle 4 is arranged outside the natural gas nozzle 3, and the ammonia nozzle 1, the natural gas nozzle 3, and the secondary air nozzle 4 are arranged in a concentric ring. 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 the secondary air, the air pressure at the wall surface of the combustion chamber cavity is reduced, and part of the high-temperature flue gas forms a backflow at the wall surface. The air temperature of the backflow high-temperature flue gas is increased, the fuel gas is ignited faster, the nozzle baffle is 15-45° to the axial direction of the burner, mainly functions to gather the fuel gas, and ensures that the fuel gas mixes with the air and the high-temperature flue gas for combustion after a certain distance of travel into the burner, reduces the temperature at the fuel gas nozzle, and prevents the fuel gas from burning too early and burning the burner nozzle.

[0041] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent replacement, and improvement of the above embodiment within the scope of the technical solution of the present application and the spirit and principles of the present application are also within the protection scope of the present application.

Claims

1. A non-premixed natural gas ammonia-blended burner, comprising an ammonia nozzle (1), a cyclone separator (2), a natural gas nozzle (3), a secondary air nozzle (4), and a nozzle baffle (5), characterized in that: The ammonia nozzle (1) is located at the center; the top of the ammonia nozzle (1) is a gradually tapering frustum, and multiple ammonia nozzles (1-1) are evenly distributed on the inclined surface of the frustum along the circumference. The angle between the inclined surface and the axial direction is 45°. There are 8 ammonia nozzles (1-1), and each ammonia nozzle (1-1) is a small hole with an axial angle of 45°. The natural gas nozzle (3) surrounds the outside of the ammonia nozzle (1); The secondary air nozzle (4) surrounds the outside of the natural gas nozzle (3); The ammonia nozzle (1), natural gas nozzle (3) and secondary air nozzle (4) are arranged concentrically around each other; the cyclone separator (2) is located between the ammonia nozzle (1) and the natural gas nozzle (3), and the multiple blades (2-1) of the cyclone separator (2) are evenly distributed around the circumference, with each blade having an inclination angle of 60°. 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 and is at 45° to the axial direction of the burner.

2. The non-premixed natural gas ammonia-blended burner according to claim 1, characterized in that: The secondary air nozzle (4) is provided with a flue gas return channel around its periphery.

3. A non-premixed natural gas ammonia-blended burner according to claim 1, characterized in that: The multiple blades (2-1) of the hydrocyclone (2) are evenly distributed around the circumference, and the tilt angle of each blade is 60°; the number of blades (2-1) is 6-12.

4. A non-premixed natural gas ammonia-blended burner according to claim 1, characterized in that: The secondary air nozzles (4) are evenly distributed along the circumference of the burner, with a quantity of 8-12, and adopt a constricted inlet.

5. A non-premixed natural gas ammonia-blended burner according to claim 1, characterized in that: The natural gas nozzles (3) are arranged in a ring array, with a quantity of 6-8.

6. A non-premixed natural gas ammonia-blended burner according to claim 5, characterized in that: Each of the natural gas nozzles (3) has multiple nozzles (3-1) on its top, and the multiple nozzles (3-1) are arranged in a ring array from the outside to the inside.

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