An ammonia-doped low-NOx combustion device for a tangentially fired coal-fired boiler

Abstract

The utility model provides a kind of for four corners circle coal-fired boiler's ammonia-doped low NOx combustion device, including pulverized coal burner, ammonia fuel nozzle and combustion air nozzle, and pulverized coal burner is at least two, each pulverized coal burner includes thick pulverized coal nozzle and light pulverized coal nozzle;Every two pulverized coal burners between are provided with an ammonia fuel nozzle, and thick pulverized coal nozzle is close to ammonia fuel nozzle setting. So set, every two pulverized coal burners, an ammonia fuel nozzle and a combustion air nozzle form ammonia coal rich combustion combination structure, the device can not only realize the stable combustion of ammonia fuel, but also can improve the burnout rate of ammonia fuel, and effectively inhibit the generation of NOx.

Description

Technical Field

[0001] This utility model belongs to the field of ammonia combustion technology for pulverized coal boilers, and specifically relates to an ammonia-infused low-NOx combustion device for a tangentially circular coal-fired boiler. Background Technology

[0002] In my country, coal-fired power plays a vital role in ensuring power supply and peak shaving. However, due to its heavy reliance on coal as a fossil fuel, the combustion process of coal-fired power plants generates large amounts of greenhouse gases such as carbon dioxide, making it one of my country's key high-carbon-emission industries. To address these challenges, the industry is actively exploring various carbon reduction technologies. Among these, introducing zero-carbon fuels to replace a certain proportion of coal in coal-fired boilers, thereby reducing carbon emissions at the energy source, is considered an ideal way for coal-fired units to achieve carbon reduction.

[0003] Among them, zero-carbon ammonia (NH3) fuel is a highly efficient hydrogen storage medium with advantages such as high energy density, easy liquefaction and storage, high safety and no carbon emissions during combustion. In addition, it can be synthesized from renewable energy sources, making it a truly green and clean energy storage medium, suitable as a zero-carbon alternative fuel for coal-fired boilers. However, the ammonia combustion process has the following technical challenges: (1) High ignition temperature, with an ignition point of 651℃, and slow flame propagation speed, narrow combustible limit range, and poor combustion reactivity, which makes ammonia combustion difficult to ignite, has poor combustion stability and is difficult to burn completely; (2) Ammonia molecules contain nitrogen atoms, and improper control during combustion can easily generate a large amount of pollutant NOx. Utility Model Content

[0004] In view of this, the purpose of this utility model is to provide an ammonia-infused low-NOx combustion device for a four-corner tangential coal-fired boiler, which can not only achieve stable combustion of ammonia fuel, but also improve the combustion rate of ammonia fuel, thereby effectively suppressing the formation of NOx.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A low-NOx combustion device for a tangential coal-fired boiler with ammonia addition includes a pulverized coal burner, an ammonia fuel nozzle, and a combustion air nozzle. The pulverized coal burner is at least two, and each pulverized coal burner includes a concentrated pulverized coal nozzle and a dilute pulverized coal nozzle.

[0007] An ammonia fuel nozzle is provided between every two pulverized coal burners, with the concentrated pulverized coal nozzle positioned close to the ammonia fuel nozzle.

[0008] Optionally, the combustion air nozzle is located on the off-fire side of the ammonia fuel nozzle.

[0009] Optionally, a first blunt body or a first diverting baffle is provided between the concentrated pulverized coal nozzle and the dilute pulverized coal nozzle.

[0010] Optionally, there is a preset distance between the pulverized coal injection port and the ammonia fuel injection port;

[0011] The preset distance is 100mm-1000mm.

[0012] Optionally, the injection path of the pulverized coal nozzle and the injection path of the ammonia fuel nozzle have a first preset angle, and the angle of the first preset angle is 0-15°.

[0013] Optionally, the injection path of the ammonia fuel nozzle and the injection path of the combustion air nozzle have a second preset angle, and the angle of the second preset angle is 0~15°.

[0014] Optionally, the gas injected from the ammonia fuel nozzle is ammonia or a mixture of ammonia and air.

[0015] Optionally, the cross-section of the ammonia fuel nozzle is circular, elliptical, square, or polygonal;

[0016] The ammonia fuel nozzle is made of a high-temperature resistant and corrosion-resistant metal or ceramic.

[0017] Optionally, a second blunt body or a second flow divider may also be provided at the ammonia fuel nozzle.

[0018] Optionally, the second diversion baffle includes a longitudinal baffle and a transverse baffle, and there is a guide angle between the longitudinal baffle and the transverse baffle;

[0019] The guide angle is 0~60°.

[0020] As can be seen from the above technical solutions, this configuration, with two pulverized coal burners, one ammonia fuel nozzle, and one combustion air nozzle forming an ammonia-coal rich combustion combination structure, has the following technical effects:

[0021] 1) The structure of placing the ammonia fuel nozzle between two pulverized coal burners can achieve stable ignition of ammonia fuel and improve the burnout rate of ammonia fuel. Specifically, the pyrolysis of pulverized coal releases a large amount of volatiles, and the released active substances such as methane or hydrogen are arranged close to the ammonia fuel nozzle and the pulverized coal burners, which is conducive to the ignition of ammonia gas and enhances the combustion intensity of ammonia fuel, reduces the ignition delay time of mixed fuel, and ensures the stable combustion of ammonia fuel. At the same time, the two pulverized coal airflows carry the ammonia fuel to burn, forming a stable rotating upward airflow, increasing the combustion path of ammonia fuel, increasing the residence time of ammonia fuel in the furnace, and having a longer burnout stroke, thereby effectively improving the burnout rate of ammonia fuel.

[0022] 2) The structure of placing the concentrated pulverized coal nozzle close to the ammonia fuel nozzle can further achieve stable ignition and combustion of ammonia fuel and effectively suppress NOx formation. Specifically, the high concentration of pulverized coal gas flow is conducive to the pyrolysis and ignition of pulverized coal, and the concentration of precipitated active substances will also be higher. The fact that both concentrated pulverized coal nozzles are close to the ammonia fuel nozzle can further facilitate the ignition of ammonia and enhance the combustion intensity of ammonia fuel, reduce the ignition delay time of mixed fuel, and ensure the stable combustion of ammonia fuel. At the same time, due to the high concentration of pulverized coal and ammonia fuel, they are in a reducing atmosphere, which is more conducive to reducing NOx. In the oxygen-deficient area, due to the reducing properties of ammonia itself, ammonia can act as both a fuel and a reducing agent for NOx formation during combustion. It can block the formation path of fuel-type NOx and also suppress the high-temperature formation of thermal NOx. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a combustion principle diagram of an ammonia-infused low-NOx combustion device for a tangential coal-fired boiler disclosed in an embodiment of the present invention.

[0025] Figure 2 This is a plan view of an ammonia-infused low-NOx combustion device for a tangential coal-fired boiler disclosed in an embodiment of the present invention.

[0026] Figure 3 This is a layout diagram of the pulverized coal burner for an ammonia-infused low-NOx combustion device for a tangential coal-fired boiler, as disclosed in an embodiment of this utility model.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100 - Pulverized coal burner, 101 - Concentrated pulverized coal nozzle, 102 - Dilute pulverized coal nozzle, 103 - First blunt body.

[0029] 200-ammonia fuel nozzle,

[0030] 300-Combustion air nozzle,

[0031] 400 - Combustion air injection path,

[0032] Injection path of 500-ammonia fuel nozzle,

[0033] 600-Corner Combustion System

[0034] 700-burnout air system,

[0035] 800-Boiler Furnace

[0036] 900 - Imaginary tangent circle. Detailed Implementation

[0037] In view of this, the core of this utility model is to provide an ammonia-infused low-NOx combustion device for a four-corner tangential coal-fired boiler, which can not only achieve stable combustion of ammonia fuel, but also improve the combustion rate of ammonia fuel and effectively suppress the formation of NOx.

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model. Please refer to... Figures 1-3 .

[0039] The ammonia-infused low-NOx combustion device for a tangentially circular coal-fired boiler disclosed in this embodiment of the invention includes a pulverized coal burner 100, an ammonia fuel nozzle 200, and a combustion air nozzle 300. There are at least two pulverized coal burners 100, each including a concentrated pulverized coal nozzle 101 and a diluted pulverized coal nozzle 102. An ammonia fuel nozzle 200 is disposed between every two pulverized coal burners 100, with the concentrated pulverized coal nozzle 101 positioned close to the ammonia fuel nozzle 200. This arrangement forms an ammonia-rich coal combustion combination structure with every two pulverized coal burners 100, an ammonia fuel nozzle 200, and a combustion air nozzle 300. This structure has the following technical advantages:

[0040] 1) The structure in which the ammonia fuel nozzle 200 is located between two pulverized coal burners 100 can achieve stable ignition of ammonia fuel and improve the burnout rate of ammonia fuel. Specifically, pulverized coal pyrolysis releases a large amount of volatiles, and the released active substances such as methane or hydrogen are released. The ammonia fuel nozzle 200 and the pulverized coal burner 100 are arranged in close proximity, which is conducive to the ignition of ammonia gas and enhances the combustion intensity of ammonia fuel, reduces the ignition delay time of mixed fuel, and ensures the stable combustion of ammonia fuel. At the same time, the two pulverized coal airflows carry ammonia fuel combustion, forming a stable rotating upward airflow, increasing the combustion path of ammonia fuel, increasing the residence time of ammonia fuel in the furnace, and having a longer burnout stroke, thereby effectively improving the burnout rate of ammonia fuel.

[0041] 2) The structure of the concentrated pulverized coal nozzle 101 close to the ammonia fuel nozzle 200 can further achieve stable ignition and combustion of ammonia fuel and effectively suppress NOx generation. Specifically, the high concentration of pulverized coal gas flow is conducive to the pyrolysis and ignition of pulverized coal, and the concentration of precipitated active substances will also be higher. Both concentrated pulverized coal nozzles 101 are close to the ammonia fuel nozzle 200, which can further facilitate the ignition of ammonia and enhance the combustion intensity of ammonia fuel, reduce the ignition delay time of mixed fuel, and ensure the stable combustion of ammonia fuel. At the same time, due to the high concentration of pulverized coal and ammonia fuel, they are in a reducing atmosphere, which is more conducive to reducing NOx. In the oxygen-deficient area, due to the reducing properties of ammonia itself, ammonia can act as both fuel and a reducing agent for NOx generation during combustion. It can block the generation path of fuel-type NOx and suppress the high-temperature generation of thermal NOx.

[0042] It should be noted that tangential combustion is a common combustion organization method in coal-fired boilers (especially large pulverized coal boilers). The principle is as follows: pulverized coal burners 100 are arranged at the four corners (or more corners) of the boiler furnace 800. The airflow (fuel + air) ejected from the pulverized coal burners 100 at each corner is not directly along the central axis of the boiler furnace 800, but is deflected at a certain angle towards the center of the boiler furnace 800, ultimately forming a rotating imaginary tangential circle 900 within the boiler furnace 800.

[0043] The low-NOx combustion device includes a corner combustion system 600 and a burnout air system 700. The corner combustion system 600 refers to the core combustion device located at the corner (e.g., four corners) of the boiler furnace 800, which includes a pulverized coal burner 100 and an ammonia fuel nozzle 200. The burnout air system 700 is a secondary air nozzle located above the main combustion zone (the area where the corner combustion system is located). The main combustion excess air coefficient is 0.6~0.95. The boiler furnace 800 is divided into a main combustion zone, a reduction zone, and a burnout zone along the height direction.

[0044] This embodiment of the utility model does not limit the specific location of the combustion air nozzle 300. Any location that meets the requirements of this utility model is within the protection scope of this utility model.

[0045] In one embodiment, the combustion air nozzle 300 disclosed in this utility model embodiment is disposed on the unfired side of the ammonia fuel nozzle 200. This arrangement can increase the oxygen content near the water-cooled wall surface, reduce the flame temperature of the water-cooled wall surface, effectively prevent corrosion of the water-cooled wall tubes caused by ammonia fuel brushing, and inhibit slagging on the water-cooled wall surface.

[0046] As a further embodiment, a first blunt body 103 or a first diverting baffle is provided between the concentrated pulverized coal nozzle 101 and the dilute pulverized coal nozzle 102 disclosed in this embodiment of the invention. Pulverized coal is separated into concentrated pulverized coal and dilute pulverized coal by a pulverized coal separator. The first blunt body 103 or the first diverting baffle separates the concentrated pulverized coal nozzle 101 and the dilute pulverized coal nozzle 102. The concentrated pulverized coal is ejected through the concentrated pulverized coal nozzle 101, and the dilute pulverized coal is ejected through the dilute pulverized coal nozzle 102. This arrangement causes the fuel gas flow to generate a recirculation zone at the outlet, entraining high-temperature flue gas and providing sufficient heat source for fuel combustion. It also increases the contact surface between the ammonia-coal gas flow and the high-temperature flue gas, enhancing combustion, and also allows the device to have high adaptability to mixed ammonia ratios. The mixed ammonia ratio (calorific value ratio) ranges from 0% to 60%.

[0047] This embodiment of the invention does not limit the preset distance between the concentrated coal powder nozzle 101 and the ammonia fuel nozzle 200; those skilled in the art can select the appropriate distance based on the actual situation.

[0048] As a preferred embodiment, the preset distance disclosed in this utility model embodiment is 100mm-1000mm.

[0049] As a specific embodiment, the preset distance disclosed in this utility model embodiment is 100mm, 300mm, 500mm, 800mm or 1000mm.

[0050] In this embodiment of the invention, the injection path of the concentrated coal powder nozzle and the injection path 500 of the ammonia fuel nozzle may be the same or different, and those skilled in the art can choose according to actual needs.

[0051] As a specific embodiment, the injection path of the pulverized coal nozzle and the injection path 500 of the ammonia fuel nozzle disclosed in this utility model embodiment have a first preset angle, and the angle of the first preset angle is 0-15°. This injection angle allows the ammonia fuel to be injected into a specific flame temperature range (850℃~1150℃) to reduce the NOx generated by the pulverized coal, thereby achieving efficient and low-carbon combustion of ammonia fuel in a tangential pulverized coal boiler.

[0052] In this embodiment of the invention, the injection path 500 of the ammonia fuel nozzle and the injection path 400 of the combustion air nozzle may be the same or different, and those skilled in the art may choose according to actual needs.

[0053] As a specific embodiment, the injection path 500 of the ammonia fuel nozzle and the injection path 400 of the combustion air nozzle disclosed in this utility model embodiment have a second preset angle, and the angle of the second preset angle is 0~15°. With this setting, the combustion air can wrap the ammonia fuel jet inside the boiler furnace 800.

[0054] It should be noted that the gas injected by the ammonia fuel nozzle 200 disclosed in this embodiment of the present invention can be ammonia or a mixture of ammonia and air.

[0055] This utility model embodiment does not specifically limit the shape of the ammonia fuel nozzle 200. Any shape and material that meets the usage requirements of this utility model are within the protection scope of this utility model.

[0056] As a specific embodiment, the cross-section of the ammonia fuel nozzle 200 disclosed in this utility model embodiment can be circular, elliptical, square or other shapes, and those skilled in the art can choose according to actual needs.

[0057] This utility model embodiment does not specifically limit the material of the ammonia fuel nozzle 200. Any shape and material that meets the usage requirements of this utility model are within the protection scope of this utility model.

[0058] As a specific embodiment, the ammonia fuel nozzle 200 disclosed in this utility model embodiment can be made of metal, high-temperature and corrosion-resistant ceramic, or other materials. Those skilled in the art can choose according to actual needs.

[0059] As a further embodiment, the ammonia fuel nozzle 200 disclosed in this embodiment of the present invention is also provided with a second blunt body or a second flow divider. This arrangement can further optimize the mixing effect of ammonia and oxidant (such as air or oxygen), enhance flame stability, improve combustion efficiency, and help control pollutant emissions.

[0060] This utility model embodiment does not limit the specific structure of the second blunt body. Any structure that meets the usage requirements of this utility model is within the protection scope of this utility model.

[0061] The second blunt body can be a non-streamlined obstacle, such as a cylinder or a square column. The second blunt body can form a recirculation zone by disturbing the flow field. A low-pressure recirculation zone will be formed downstream of the second blunt body, which will reverse the high-temperature flue gas generated by combustion and draw it to the vicinity of the nozzle outlet, providing continuous heat for the ignition of ammonia. The disturbance in the recirculation zone will enhance the turbulent mixing of ammonia and oxidant, making the unburned mixture more uniform before entering the flame zone, reducing the phenomenon of local over-rich or over-lean. In addition, the high temperature in the recirculation zone can accelerate the decomposition and oxidation reaction of ammonia, while controlling the recirculation intensity to avoid excessively high local temperatures.

[0062] This utility model embodiment does not limit the specific structure of the second diversion baffle. Any structure that meets the usage requirements of this utility model is within the protection scope of this utility model.

[0063] As one embodiment, the second diversion baffle disclosed in this utility model embodiment includes a longitudinal baffle and a transverse baffle, wherein the longitudinal baffle and the transverse baffle have a guide angle.

[0064] As a specific embodiment, the guide angle disclosed in this utility model embodiment is 0~60°. With this configuration, the longitudinal baffle and the transverse baffle can divide the ammonia gas flow into multiple sub-flows, while forcing the oxidant (such as air) to flow in the gap between the longitudinal baffle and the transverse baffle, thereby significantly increasing the contact interface between ammonia and oxidant and improving the mixing rate.

[0065] Of course, the second diversion baffle disclosed in this embodiment of the present invention may also only have a longitudinal baffle or a transverse baffle, and those skilled in the art can choose according to actual needs.

[0066] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0068] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ammonia-doped low NOx combustion apparatus for a tangentially fired coal-fired boiler, characterized by, It includes a pulverized coal burner, an ammonia fuel nozzle, and a combustion air nozzle, wherein there are at least two pulverized coal burners, and each pulverized coal burner includes a concentrated pulverized coal nozzle and a dilute pulverized coal nozzle; An ammonia fuel nozzle is provided between every two pulverized coal burners, with the concentrated pulverized coal nozzle positioned close to the ammonia fuel nozzle.

2. The ammonia-infused low-NOx combustion device for a tangential coal-fired boiler according to claim 1, characterized in that, The combustion air nozzle is located on the off-fire side of the ammonia fuel nozzle.

3. The ammonia-infused low-NOx combustion device for a tangentially circular coal-fired boiler according to claim 1, characterized in that, A first blunt body or a first diverting baffle is provided between the concentrated pulverized coal nozzle and the dilute pulverized coal nozzle.

4. The ammonia blended low NOx combustion apparatus for tangentially fired coal fired boilers as claimed in claim 1 wherein, There is a preset distance between the concentrated coal injection port and the ammonia fuel injection port; The preset distance is 100mm-1000mm.

5. The ammonia blended low NOx combustion apparatus for tangentially fired coal fired boilers as claimed in claim 1 wherein, The injection paths of the concentrated coal injection nozzle and the ammonia fuel injection nozzle have a first preset angle, and the angle of the first preset angle is 0-15°.

6. The ammonia blended low NOx combustion apparatus for tangentially fired coal fired boilers as claimed in claim 1 wherein, The injection path of the ammonia fuel nozzle and the injection path of the combustion air nozzle have a second preset angle, and the angle of the second preset angle is 0~15°.

7. The ammonia-doped low NOx combustion apparatus for tangentially fired coal-fired boilers according to claim 1, characterized in that, The gas injected from the ammonia fuel nozzle is ammonia or a mixture of ammonia and air.

8. The ammonia-doped low NOx combustion apparatus for tangentially fired coal-fired boilers according to claim 1, characterized in that, The cross-section of the ammonia fuel nozzle is circular, elliptical, square, or polygonal; The ammonia fuel nozzle is made of a high-temperature resistant and corrosion-resistant metal or ceramic.

9. The ammonia blended low NOx combustion apparatus for tangentially fired coal fired boilers as claimed in claim 1 wherein, A second blunt body or a second flow divider is also provided at the ammonia fuel nozzle.

10. The ammonia-infused low-NOx combustion device for a tangential coal-fired boiler according to claim 9, characterized in that, The second diversion baffle includes a longitudinal baffle and a transverse baffle, and there is a guide angle between the longitudinal baffle and the transverse baffle; The guide angle is 0~60°.

Images