A high-power pure ammonia low-nitrogen burner

Abstract

The application discloses a high-power pure-ammonia low-nitrogen combustor, which comprises a wind box, a first-stage air distribution air duct, a second-stage air distribution air duct, a third-stage air distribution air duct and a fourth-stage air distribution passage, a point ignition device is arranged in the first-stage air distribution air duct, and a tangential cyclone device is arranged in the fourth-stage air distribution passage; a central cyclone disc is fixedly connected to the front end of the first-stage air distribution air duct, a plurality of annularly-arranged first-stage ammonia fuel nozzles are arranged in the second-stage air distribution air duct, and the first-stage ammonia fuel nozzles are connected with first-stage ammonia fuel distribution rings through connecting pipes; a flue gas entrainment plate with a plurality of through holes is arranged at the front end of the third-stage air distribution air duct, and front ends of a plurality of second-stage tubular ammonia fuel injection guns pass through the flue gas entrainment plate; a plurality of third-stage ammonia fuel injection guns are arranged in the fourth-stage air distribution passage, and each tubular ammonia fuel injection gun is connected with a corresponding ammonia fuel distribution ring; a system cut-off valve and an adjusting valve are arranged on a conveying pipeline of each ammonia fuel distribution ring; the combustor can realize multiple-stage fuel grading and multiple-stage air distribution, and can realize stable combustion through self-entrainment and backflow of multi-stage high-temperature flue gas in a stable combustion area, so that stable combustion of ammonia fuel is realized and a low-NOx emission effect is achieved.

Description

Technical Field

[0001] This invention relates to a pure ammonia burner, and more particularly to a high-power pure ammonia low-NOx burner. Background Technology

[0002] With economic development and social progress, the country's demand for energy is increasing. However, excessive use of fossil fuels will lead to environmental pollution and the greenhouse effect. Therefore, exploring a zero-carbon fuel for co-firing in boilers is a highly promising carbon emission reduction route and is of great significance to the realization of the "dual carbon" goal.

[0003] From the perspective of the current state of industry development, ammonia is a new type of zero-carbon fuel that is most promising for large-scale replacement of fossil fuels, and it has the following advantages:

[0004] 1) Ammonia has a high energy density, and its volumetric energy density is higher than that of hydrogen.

[0005] 2) Ammonia is easily liquefied. It can be liquefied at room temperature by pressurizing it to 1.03 MPa, while hydrogen requires pressurization to 70 MPa, which gives it a cost advantage in transportation.

[0006] 3) The supporting infrastructure for the storage and transportation of ammonia is relatively complete and can support industrial applications.

[0007] 4) The explosion limit of ammonia is 15-28%, while the explosion limit of hydrogen is 4-75%. Ammonia has better safety and is less likely to catch fire or explode during transportation.

[0008] However, ammonia has a low calorific value and a relatively high auto-ignition temperature of 650℃, resulting in poor ignition performance. Existing ammonia fuel burners suffer from insufficient mixing of ammonia fuel and air, making stable combustion difficult. Furthermore, ammonia combustion carries the risk of exceeding nitrogen oxide emission standards. Improper combustion organization can easily lead to excessive nitrogen oxide emissions. Summary of the Invention

[0009] The purpose of this invention is to address the aforementioned shortcomings of the prior art by providing a high-power pure ammonia low-NOx burner. This burner can achieve good mixing of ammonia fuel and air, as well as reasonable zoned and stratified combustion, thereby realizing multiple stages of fuel and air distribution. Through multi-stage high-temperature flue gas self-entrainment and recirculation zone for stable combustion, it achieves stable combustion of ammonia fuel, high burnout rate, and low NOx emissions.

[0010] To achieve the above objectives, the present invention provides a high-power pure ammonia low-NOx burner, comprising a wind box, and a primary air distribution duct, a secondary air distribution duct, a tertiary air distribution duct, and a quaternary air distribution channel arranged sequentially from the inside to the outside. An ignition device is provided in the primary air distribution duct, and a tangential cyclone separator is provided in the quaternary air distribution channel. The invention is characterized in that a central cyclone disk is fixedly connected to the front end of the primary air distribution duct, and several annularly arranged primary ammonia fuel nozzles are provided in the secondary air distribution duct outside the central cyclone disk. Each primary ammonia fuel nozzle is connected to a primary ammonia fuel distribution ring via a connecting pipe, and the axial directions of adjacent primary ammonia fuel nozzles are radially inward and radially outward, respectively. The system is inclined; a flue gas suction plate is provided at the front end of the three-stage air distribution duct, and the flue gas suction plate has several through holes. The front ends of several two-stage tubular ammonia fuel spray guns pass through the flue gas suction plate, and each two-stage tubular ammonia fuel spray gun is connected to a two-stage ammonia fuel distribution ring; several three-stage ammonia fuel spray guns are provided in the four-stage air distribution duct, and each three-stage tubular ammonia fuel spray gun is connected to a three-stage ammonia fuel distribution ring. The front end of the four-stage air distribution duct and the front end of each three-stage tubular ammonia fuel spray gun are inclined radially outward; each ammonia fuel distribution ring is located outside the air box, and each ammonia fuel distribution ring is connected to its respective fuel delivery pipeline. Each delivery pipeline is equipped with a system shut-off valve and a regulating valve.

[0011] In use, the primary, secondary, tertiary, and quaternary air distribution ducts distribute air through a bellows. A central swirl plate is fixed within the secondary air distribution duct. This large-scale central swirl plate can entrain high-temperature flue gas for recirculation, forming a primary high-temperature recirculation zone, which is beneficial for the ignition and stable combustion of the primary annular ammonia fuel. A high-temperature flue gas entrainment plate is arranged at the front end of the tertiary air distribution duct. Its unique through-hole structure forms a primary negative pressure zone, promoting the recirculation of high-temperature flue gas to form a secondary recirculation zone, providing better combustion temperature conditions for the secondary ammonia fuel. A tangential swirl converter is arranged at the inlet of the quaternary air distribution channel, which can be used to adjust the airflow and swirl intensity of the quaternary air distribution. Simultaneously, the quaternary swirl... After leaving the burner nozzle, the air expands outwards, creating a secondary negative pressure zone at the injection point of the third-stage ammonia fuel, thus forming a third-stage recirculation zone. The recirculated high-temperature flue gas provides sufficient heat to stably ignite the third-stage ammonia fuel. The superimposed effect of the first, second, and third-stage high-temperature flue gas recirculation zones, combined with the first-stage annular ammonia fuel nozzle, the second-stage tubular ammonia fuel lance, and the third-stage ammonia fuel lance arranged in three rings circumferentially, effectively enhances the mixing of fuel and air, forming a multi-layered annular flame. This achieves multi-stage fuel and multi-stage air distribution, and through the stable combustion of the multi-stage high-temperature flue gas self-entrainment recirculation zone, the ammonia fuel injected into the furnace at each stage can ignite more rapidly and burn continuously. Complete combustion ensures full combustion of ammonia fuel, improving overall combustion efficiency and preventing the formation of a combustion field with large temperature deviations due to concentrated heat. Furthermore, the recirculated high-temperature flue gas lowers the peak combustion temperature at the initial stage. Simultaneously, the reducing agents such as H2 produced by pyrolysis of NH3 enhance the reduction of nitrogen oxides in the early stages of combustion, thus reducing NOx emissions. The burner air distribution is divided into four streams: primary, secondary, tertiary, and quaternary, achieving multi-stage air distribution. This prevents the overall combustion process from operating under equivalence ratio conditions, further suppressing NOx formation and reducing nitrogen oxide emissions. The primary, secondary, and quaternary ammonia fuels... Each stage of ammonia fuel is equipped with its own ammonia fuel distribution ring, fuel delivery pipeline, system shut-off valve, and regulating valve to achieve gas distribution, delivery, precise control, and shut-off of each stage of ammonia fuel injection device. The axial direction of two adjacent stage ammonia fuel nozzles is inclined radially inward and radially outward, respectively, which can realize the angular staged combustion of ammonia fuel, reduce nitrogen oxides, and at the same time, the nozzles inclined radially inward face the ignition device, making ignition easier, while the nozzles inclined radially outward are more likely to ignite the fuel in the outer ring when spraying outward, realizing the associated operation of fuel. The front end of the fourth-stage air distribution channel and the front end of each third-stage tubular ammonia fuel injection gun are all inclined radially outward, which can improve the effect of zoned combustion.

[0012] As a further improvement of the present invention, the primary ammonia fuel nozzle, the secondary tubular ammonia fuel spray gun and the tertiary tubular ammonia fuel spray gun are all evenly distributed on the circumference; this can make the combustion flame more uniform, avoid the generation of local high temperature areas, effectively control the generation of nitrogen oxides, and achieve full mixing of fuel and air.

[0013] As a further improvement of the present invention, the several through holes of the flue gas suction plate are arranged radially in layers and evenly distributed in the same layer, and each secondary tubular ammonia fuel spray gun is located radially between the two layers of through holes; a secondary reflux zone can be formed on the inner and outer sides of each secondary tubular ammonia fuel spray gun, providing better combustion temperature conditions for the secondary ammonia fuel;

[0014] As a further improvement of the present invention, the air box is connected to the air distribution system pipeline, and the air distribution system pipeline is equipped with a system regulating valve; during operation, the air volume of each burner can be adjusted to achieve the best combustion conditions.

[0015] In summary, this invention can achieve good mixing of ammonia fuel and air and reasonable zonal and stratified combustion, forming independent flame layers and ensuring stable combustion process while achieving low NOx emissions and high-efficiency burnout. Attached Figure Description

[0016] Figure 1 This is a front view of an embodiment of the present invention.

[0017] Figure 2 for Figure 1 The P-direction view. Detailed Implementation

[0018] The invention will be further described below with reference to the accompanying drawings.

[0019] like Figures 1 to 2As shown, this embodiment of a high-power pure ammonia low-NOx burner includes a wind box 1, and a primary air distribution duct 2, a secondary air distribution duct 3, a tertiary air distribution duct 4, and a quaternary air distribution channel 5 arranged sequentially from the inside to the outside. An ignition device 6 is installed in the primary air distribution duct 2, and a tangential cyclone separator 7 is installed in the quaternary air distribution channel 5. A large-scale central cyclone disk 8 is welded and fixed to the front end of the primary air distribution duct 2. Several nozzles 9 are fixedly connected to the secondary air distribution duct 3 outside the central cyclone disk 8. A series of primary ammonia fuel nozzles 10 are arranged in a ring and evenly distributed on the circumference. The axial direction of adjacent primary ammonia fuel nozzles 10 is inclined radially inward and radially outward, respectively. Each primary ammonia fuel nozzle 10 is connected to a primary ammonia fuel distribution ring 11 through its own connecting pipe 22. A flue gas suction plate 12 is welded and fixed at the front end of the tertiary air distribution duct 4. The flue gas suction plate 12 has several through holes 13. The front ends of several secondary tubular ammonia fuel spray guns 14, which are evenly distributed on the circumference, pass through the flue gas suction plate 12. Several through holes 13 are arranged radially in three layers, evenly distributed within the same layer. Each secondary tubular ammonia fuel spray gun 14 is located radially between the inner and outer layers of through holes 13, and each secondary tubular ammonia fuel spray gun 14 is connected to the secondary ammonia fuel distribution ring 15. Several tertiary ammonia fuel spray guns 16 are evenly distributed circumferentially within the fourth-stage air distribution channel 5. The front end of the fourth-stage air distribution channel 5 and the front end of each tertiary tubular ammonia fuel spray gun 16 are inclined radially outwards. Each tertiary tubular ammonia fuel spray gun 16 is connected to the tertiary ammonia fuel distribution ring 15. Fuel distribution ring 17 is connected; each stage of ammonia fuel distribution ring 11, 15, and 17 is located outside the air box 1. The connecting pipe 22, the secondary tubular ammonia fuel spray gun 14, and the tertiary ammonia fuel spray gun 16 all pass through the rear panel of the air box 1. Each stage of ammonia fuel distribution ring 11, 15, and 17 is connected to its respective fuel delivery pipeline. Each delivery pipeline is equipped with a system shut-off valve 18 and a regulating valve 19. The air box 1 is connected to the air distribution system pipeline 20. The air distribution system pipeline 20 is equipped with a system regulating valve 21.

[0020] In use, the ignition device 6 is used to ignite the burner; the primary air distribution duct 2, secondary air distribution duct 3, tertiary air distribution duct 4, and quaternary air distribution channel 5 are all connected to the air box 1 for air distribution. The burner air distribution is divided into four streams: primary air, secondary air, tertiary air, and quaternary air, realizing multiple air classification; each level of air distribution is sent to the burner through the primary air distribution duct 2, secondary air distribution duct 3, tertiary air distribution duct, and quaternary air distribution channel 5, and each level of air distribution channel is concentric from the inside to the outside. The arrangement is as follows: Primary airflow provides ignition stage airflow through primary air distribution duct 2; secondary airflow, after passing through secondary air distribution duct 3 and the large-scale central swirl plate 8, can entrain high-temperature flue gas to form a primary high-temperature recirculation zone, which is beneficial for the ignition and stable combustion of primary annular ammonia fuel; tertiary airflow, through tertiary air distribution duct 4 and the high-temperature flue gas entrainment plate 12 arranged at the front end, forms a primary negative pressure zone due to the unique through holes 13 of the high-temperature flue gas entrainment plate 12, promoting the recirculation of high-temperature flue gas to form a secondary recirculation zone, thus providing... Secondary ammonia fuel provides better combustion temperature conditions; the fourth-stage airflow forms a swirling airflow after passing through the fourth-stage air distribution channel 5 and the tangential cyclone separator 7 arranged at the inlet. The tangential cyclone separator 7 can adjust the airflow and swirling intensity of the fourth-stage airflow. At the same time, the fourth-stage swirling airflow expands in all directions after leaving the burner nozzle, forming a secondary negative pressure zone at the injection point of the tertiary ammonia fuel, thus forming a tertiary recirculation zone. The recirculated high-temperature flue gas can provide sufficient heat to stably ignite the ammonia fuel. The superposition effect of the primary, secondary, and tertiary high-temperature flue gas recirculation zones, plus the ammonia fuel of each stage being sent into the burner from the primary ammonia fuel nozzle 10, the secondary tubular ammonia fuel injector 14, and the tertiary ammonia fuel injector 16, and the appropriate number of nozzles or injectors arranged in three layers along a 360° annular area, inject fuel into the furnace at different flow rates and speeds. The opening size and number of nozzles or injectors are different, and the injection angle is different. During combustion, a multi-layered annular flame is formed, so that the fuel forms a layered and uniform combustion flame in the circumferential direction.Taking a typical 30MW ammonia burner as an example: A total of 24 primary annular ammonia fuel nozzles 10 are provided. Since the axial direction of adjacent primary ammonia fuel nozzles 10 is inclined radially inward and radially outward respectively, 12 of them spray inward at an angle A1, and the other 12 spray outward at an angle A2, arranged alternately in the circumferential direction, achieving angle-staged combustion of ammonia fuel; 18 secondary tubular ammonia fuel injectors 14 are provided, with horizontal nozzle angles; 24 tertiary ammonia fuel injectors 16 are provided, 12 of which spray at an angle A3 (10°) radially outward, and the other 12 spray at an angle A3 (15°) radially outward, arranged alternately in the circumferential direction, effectively enhancing fuel-air mixing and reasonable zonal and stratified combustion, forming a multi-layered annular flame, thereby achieving multi-stage fuel and multi-stage air distribution. Through multi-stage high-temperature flue gas self-entrainment and recirculation zone stable combustion, the ammonia fuel injected into the furnace at each stage can achieve… Rapider ignition and sustained combustion ensure complete combustion of ammonia fuel, improving overall combustion efficiency and preventing the formation of a combustion field with large temperature deviations due to concentrated heat. Furthermore, the return of high-temperature flue gas lowers the peak combustion temperature in the initial stages of combustion. Simultaneously, the reducing agents such as H produced from pyrolysis of NH3 enhance the reduction of nitrogen oxides in the early stages of combustion, thus reducing NOx emissions. The air distribution is divided into four stages: primary, secondary, tertiary, and quaternary, achieving multi-stage air distribution in the burner. This prevents the overall combustion process from operating under equivalence ratio conditions, further suppressing NOx formation and reducing nitrogen oxide emissions. The angle-staged combustion primary ammonia fuel nozzle 10 further reduces nitrogen oxides. The radially inward-sloping nozzle 10, facing the ignition device, facilitates ignition, while the radially outward-sloping nozzle makes it easier to ignite the outer ring fuel during external injection, achieving coordinated fuel activation. Each of the primary, secondary, and tertiary ammonia fuel systems is equipped with its own ammonia fuel distribution ring, fuel delivery pipeline, system shut-off valve 18, and regulating valve 19, which are used to achieve gas distribution, delivery, precise control, and shut-off of the ammonia fuel injection devices at each stage. The air volume of each burner can be adjusted during operation through the system regulating valve 21 to achieve optimal combustion conditions.

[0021] The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.

Claims

1. A high-power pure ammonia low-nitrogen combustor, comprising a wind box, a first air distribution channel, a second air distribution channel, a third air distribution channel and a fourth air distribution channel arranged in sequence from inside to outside, a ignition device is arranged in the first air distribution channel, and a tangential cyclone is arranged in the fourth air distribution channel; characterized in that: The center cyclone disc is fixed outside the front end of the primary air distribution air duct, a plurality of annularly arranged primary ammonia fuel nozzles are arranged in the secondary air distribution air duct outside the center cyclone disc, the primary ammonia fuel nozzles are connected with the primary ammonia fuel distribution ring through connecting pipes, the axial directions of the adjacent two primary ammonia fuel nozzles are respectively inclined to the radial inner side and the radial outer side; the flue gas entraining plate is arranged at the front end of the tertiary air distribution air duct, the flue gas entraining plate is provided with a plurality of through holes, the front ends of the plurality of secondary tubular ammonia fuel spray guns pass through the flue gas entraining plate, the secondary tubular ammonia fuel spray guns are connected with the secondary ammonia fuel distribution ring; the plurality of tertiary ammonia fuel spray guns are arranged in the quaternary air distribution channel, the tertiary tubular ammonia fuel spray guns are connected with the tertiary ammonia fuel distribution ring, the front end of the quaternary air distribution channel and the front ends of the tertiary tubular ammonia fuel spray guns are all inclined to the radial outer side; the ammonia fuel distribution rings of all levels are located outside the air bellow, the ammonia fuel distribution rings of all levels are connected with the fuel delivery pipelines thereof, the system cut-off valves and the regulating valves are arranged on the delivery pipelines.

2. A high duty pure ammonia low nitrogen burner as claimed in claim 1, wherein: The primary ammonia fuel nozzles, the secondary tubular ammonia fuel spray guns and the tertiary tubular ammonia fuel spray guns are circumferentially distributed.

3. A high-power pure ammonia low-nitrogen burner according to claim 1 or 2, characterized in that: The plurality of through holes of the flue gas entraining plate are radially layered and uniformly arranged in the same layer, and the secondary tubular ammonia fuel spray guns are radially located between the two layers of through holes.

4. A high duty pure ammonia low nitrogen burner as claimed in claim 3, wherein: The air bellow is connected with the air distribution system pipeline, and the system regulating valve is arranged on the air distribution system pipeline.

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