Ammonia-doped combustion system of front and back wall opposed firing boiler

Abstract

The invention discloses an ammonia-doped combustion system of a front and back wall opposed firing boiler, and relates to the technical field of coal-fired power generation. The combustion system comprises a hearth, a pure ammonia combustor, an ammonia-coal mixed combustion combustor and a pulverized coal combustor. The hearth comprises a front wall, a left wall, a rear wall and a right wall which are sequentially connected, and the front wall and the rear wall are each provided with an over fire air nozzle; a plurality of pure ammonia combustors, a plurality of ammonia-coal mixed combustion combustors and a plurality of pulverized coal combustors which are sequentially distributed from top to bottom are mounted on the front wall and the rear wall below the spontaneous combustion over air nozzles; and a plurality of pure ammonia combustors are mounted on the left wall and the right wall. According to the ammonia-doped combustion system, the structure of the ammonia-doped combustion system is improved, the problems that when coal such as lignite and meagre coal is mixed with the ammonia for combustion, the ammonia is not easy to burn out, the combustion stability is poor, and the NOx emission is high are solved, meanwhile, the ammonia-doped combustion amount of the front-and-back wall opposed firing boiler can reach 30% or above, the NOx emission is low, and the ammonia-doped combustion system is suitable for the front-and-back wall opposed firing boiler. And low-carbon operation can be effectively carried out.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to an ammonia-infused combustion system for a boiler with opposing front and rear walls. Background Technology

[0002] Under the requirements of carbon peaking and carbon neutrality, low-carbon operation of coal-fired power generating units is imperative. Ammonia blending is one approach to low-carbon operation. In the context of deep peak shaving, opposed-wall boilers need to consider NOx emissions from boiler combustion. x The emissions and stable combustion at low loads are achieved, and then ammonia is added for combustion.

[0003] In existing technology, the burners of dual-fuel combustion front and rear wall opposed boilers include an ammonia-coal pulverized coal mixing combustion zone, a pulverized coal combustion zone, and a burnout zone. The ammonia-coal pulverized coal mixing combustion zone is equipped with multiple layers of ammonia-coal pulverized coal dual-fuel burners to achieve the co-firing of ammonia and pulverized coal. The pulverized coal combustion zone is located on both sides of the ammonia-coal pulverized coal mixing combustion zone, with one layer of pulverized coal burners. The burnout zone is located at the top and is equipped with air nozzles. However, when this combustion system burns lignite, lean coal, or other coal types, the ammonia is difficult to burn completely when co-firing, resulting in poor combustion stability and high NO content. x The high emissions result in incomplete combustion in this combustion system, leading to NO... x Its emissions are relatively high. Summary of the Invention

[0004] The main objective of this invention is to provide an ammonia-blended combustion system for a front and rear wall opposed-wall boiler, aiming to solve the problems of poor ammonia combustion stability, NO content, and other issues when burning lignite, lean coal, and other coal types. x To address the issue of high emissions, efforts should be made to improve the combustion efficiency of coal types such as lignite and lean coal, and reduce NOx emissions. x The emissions.

[0005] To achieve the above objectives, the present invention proposes an ammonia-blended combustion system for a front and rear wall opposed boiler, comprising: The furnace includes a front wall, a left wall, a rear wall and a right wall connected in sequence, and the front wall and the rear wall are each provided with a plurality of burnout air nozzles for injecting burnout air; Multiple pure ammonia burners, multiple ammonia-coal co-fired burners, and multiple pulverized coal burners are provided. The front wall and the rear wall are each equipped with a number of pure ammonia burners, a number of ammonia-coal co-fired burners, and a number of pulverized coal burners arranged sequentially from top to bottom below their respective burnout air nozzles. The left wall and the right wall are each equipped with a number of pure ammonia burners. Wherein, the pure ammonia burners on the front wall and the pure ammonia burners on the rear wall are symmetrically arranged along the same center line; and / or, the ammonia-coal co-fired burners on the front wall and the ammonia-coal co-fired burners on the rear wall are symmetrically arranged along the same center line.

[0006] Optionally, the pure ammonia burner includes an ammonia pipe, a central air duct, an outer secondary air sleeve, airflow regulating blades, an airflow regulating device, and a drive device. One end of the ammonia pipe is adapted to introduce ammonia gas. One end of the central air duct is connected to the ammonia pipe via a first support member and embedded within the ammonia pipe. The portion of the central air duct embedded within the ammonia pipe extends along the length of the ammonia pipe into the furnace chamber. The central air duct and the ammonia pipe form an ammonia gas flow channel. The central air duct is connected to the secondary air box. The ammonia pipe is mounted on the outer secondary air sleeve via a second support member, forming an outer secondary air channel with it. The airflow regulating blades are welded to the outside of the ammonia pipe and are used to generate rotating airflow. The airflow regulating device is mounted on the ammonia pipe and connected to the drive device. The airflow regulating device is a conical disc type and is connected to the outer secondary air sleeve, used to adjust the airflow entering the outer secondary air channel.

[0007] Optionally, the ammonia-coal co-fired burner includes a primary air-coal duct, a light pulverized coal duct, a concentrated pulverized coal duct, a central air duct, an annular ammonia duct, an ammonia connecting pipe, an ammonia-coal exhaust gas nozzle, an ammonia-coal concentration device, external secondary air fixed blades, external secondary air regulating blades, and internal secondary air fixed blades. One end of the primary air-coal duct is adapted to allow coal powder to pass through. The primary air-coal duct is equipped with a concentrated and diluted coal powder separator, which is used to separate coal powder into concentrated coal powder and diluted coal powder. The diluted coal powder side of the concentrated and diluted coal powder separator is connected to one end of the diluted coal powder duct, and the other end of the diluted coal powder duct is equipped with an ammonia coal exhaust gas nozzle. The concentrated coal powder side of the concentrated and diluted coal powder separator is connected to the concentrated coal powder duct. The central air duct is embedded in the concentrated coal powder duct and connected by an internal support member. The central air duct and the concentrated coal powder duct form an ammonia-coal flow channel. The annular ammonia gas duct is installed on the outside of the concentrated coal powder duct and connected to the ammonia-coal flow channel through multiple ammonia gas connecting pipes. The ammonia-coal concentration device is installed on the central air duct and is used to uniformly disperse ammonia gas and coal powder. An inner secondary air sleeve is installed on the outside of the concentrated coal powder pipeline to form an inner secondary air duct, and an outer secondary air sleeve is installed on the outside of the inner secondary air sleeve to form an outer secondary air duct. The external secondary air fixed blades and the external secondary air regulating blades are respectively arranged in the external secondary air duct and are used to regulate the swirl direction and intensity of the external secondary air. The internal secondary air fixed blades are arranged in the internal secondary air duct and are used to regulate the swirl direction of the internal secondary air.

[0008] Optionally, the ammonia-coal co-fired burner further includes a flow equalization device disposed in the pulverized coal pipeline, the flow equalization device being used to disperse ammonia and pulverized coal.

[0009] Optionally, the annular ammonia gas pipeline is provided on the outer side of the pulverized coal pipeline, and the annular ammonia gas pipeline is connected to the ammonia-coal flow channel through multiple ammonia gas connecting pipes.

[0010] Optionally, the centerline of each of the ammonia gas connecting pipes forms a first angle with the centerline of the flow equalization device, with the opening facing away from the ammonia-coal exhaust gas nozzle, and the first angle is an acute angle.

[0011] Optionally, the centerline of the ammonia connection pipe and the centerline of the ammonia-coal concentration device form a second angle with the opening facing the concentrated-dilute coal powder separator, and the second angle is an acute angle.

[0012] Optionally, the first included angle is 45°; and / or, the second included angle is 45°.

[0013] Optionally, the ammonia-blended combustion system of the front and rear wall opposed boiler further includes an ammonia input pipe, which is arranged in a ring around the inner wall of the furnace and connected to the pure ammonia burner and the ammonia-coal co-fired burner respectively.

[0014] Optionally, the front wall and the rear wall are arranged with four layers of burners from top to bottom. The first layer is equipped with multiple pure ammonia burners, and each pure ammonia burner is provided with a burnout air nozzle above it. The second layer is equipped with multiple ammonia-coal co-fired burners. The third and fourth layers are equipped with multiple pulverized coal burners. Two or more pure ammonia burners are evenly arranged on the left and right walls at the same height as the first layer.

[0015] In the technical solution of this invention, the ammonia-blended combustion system of the front and rear wall opposed boiler includes a furnace, a pure ammonia burner, an ammonia-coal co-fired burner, and a pulverized coal burner. The furnace includes a front wall, a left wall, a rear wall, and a right wall connected in sequence. Multiple burnout air nozzles for injecting burnout air are provided on both the front and rear walls. Below each burnout air nozzle on both the front and rear walls, several pure ammonia burners, several ammonia-coal co-fired burners, and several pulverized coal burners are installed in a top-to-bottom arrangement. Several pure ammonia burners are installed on both the left and right walls. The pure ammonia burners on the front and rear walls are symmetrically arranged along the same center line; and / or, the ammonia-coal co-fired burners on the front and rear walls are symmetrically arranged along the same center line. It is understood that this invention improves the structure of the ammonia-blended combustion system in a front and rear wall opposed-wall boiler. By setting up multiple layers of burners in the furnace, with pure ammonia burners arranged in the upper layer of the front and rear walls, ammonia-coal co-fired burners arranged in the middle layer, and pulverized coal burners arranged in the bottom layer, it effectively solves the problems of poor ammonia combustion stability, NO content, and other issues when ammonia is blended. xTo address the high emissions issue, pure ammonia burners are installed on the left and right walls, resulting in more complete combustion and better combustion stability, especially when burning lignite and lean coal. Furthermore, the ammonia-blended combustion system in this front and rear wall-opposed boiler allows for ammonia blending of over 30% into the combustion volume, and NO... x With low emissions, it can effectively implement low-carbon operation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the front wall structure in one embodiment of the ammonia-infused combustion system of the front and rear wall opposed boiler of the present invention; Figure 2 This is a schematic diagram of the rear wall structure in one embodiment of the ammonia-infused combustion system of the front and rear wall opposed boiler of the present invention; Figure 3 This is a schematic diagram of the left wall structure in one embodiment of the ammonia-infused combustion system of the front and rear wall opposed boiler of the present invention; Figure 4 This is a schematic diagram of the right wall structure in one embodiment of the ammonia-infused combustion system of the front and rear wall opposed boiler of the present invention; Figure 5 This is a schematic diagram of the structure of a pure ammonia burner in one embodiment of the ammonia-blended combustion system of the front and rear wall opposed boiler of the present invention; Figure 6 This is a schematic diagram of the structure of the ammonia-coal co-fired burner in one embodiment of the ammonia-coal combustion system of the front and rear wall opposed boiler of the present invention.

[0018] Explanation of icon numbers: 1. Pure ammonia burner; 2. Ammonia-coal co-fired burner; 3. Pulverized coal burner; 4. Burnout air nozzle; 5. Ammonia input pipe; 6. Secondary air box; 7. Wall-mounted air duct; 11. Ammonia pipe; 12. Central air duct; 13. Air volume regulating blade; 14. Air volume regulating device; 15. Drive device; 16. External secondary air sleeve; 21. Primary air-coal duct; 22. Light pulverized coal duct; 23. Concentrated pulverized coal duct; 24. Central air duct; 25. Annular ammonia duct; 26. Ammonia connecting pipe; 27. Flow equalization device; 28. Ammonia-coal exhaust gas nozzle; 29. ​​Ammonia-coal concentration device; 210. External secondary air fixed blade; 211. External secondary air regulating blade; 212. Internal secondary air fixed blade.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. The word "and / or" throughout the text means including three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. The technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] This invention proposes an ammonia-infused combustion system for a boiler with opposing front and rear walls.

[0025] Reference Figures 1 to 4In one embodiment of the present invention, the ammonia-blended combustion system of the front and rear wall opposed boiler includes a furnace, a pure ammonia burner 1, an ammonia-coal co-fired burner 2, and a pulverized coal burner 3. The furnace includes a front wall, a left wall, a rear wall, and a right wall connected in sequence. Multiple burnout air nozzles 4 for injecting burnout air are provided on both the front and rear walls. Below each burnout air nozzle 4, several pure ammonia burners 1, several ammonia-coal co-fired burners 2, and several pulverized coal burners 3 are installed in sequence from top to bottom on both the front and rear walls. Several pure ammonia burners 1 are installed on both the left and right walls. The pure ammonia burners 1 on the front wall and the pure ammonia burners 1 on the rear wall are symmetrically arranged along the same center line; and / or, the ammonia-coal co-fired burners 2 on the front wall and the ammonia-coal co-fired burners 2 on the rear wall are symmetrically arranged along the same center line.

[0026] In this embodiment, the furnace is generally rectangular. Conventionally, the wall in front of the boiler is considered the front wall, the wall behind it the rear wall, the wall on the left the left wall, and the wall on the right the right wall the right wall. The front, left, rear, and right walls can all be water-cooled walls. Water-cooled walls can efficiently absorb heat and generate steam, and also protect the furnace walls, support the boiler, and make the overall structure safer. Furthermore, the furnace can also be a polygon with at least four walls or other irregular shapes; this is not limited to these specific shapes.

[0027] In this embodiment, the pure ammonia burner 1, the ammonia-coal co-fired burner 2, and the pulverized coal burner 3 can all be conventional pure ammonia burner 1, ammonia-coal co-fired burner 2, and pulverized coal burner 3, or the improved burners mentioned below.

[0028] It is understood that this invention improves the structure of the ammonia-blended combustion system in a front-and-rear wall opposed-flow boiler. By setting up multiple layers of burners in the furnace, with a pure ammonia burner 1 in the upper layer, ammonia-coal co-fired burner 2 in the middle layer, and pulverized coal burner 3 in the bottom layer, the flame generated by the combustion of pulverized coal in the bottom layer spreads to the middle and upper combustion zones, effectively solving the problems of poor ammonia combustion stability, NO content, and other issues when ammonia is blended. x The high emissions issue, especially when burning lignite and lean coal, is addressed through more complete combustion and better combustion stability. Furthermore, the ammonia-blended combustion system in this front and rear wall opposed boiler allows for ammonia blending of over 30% into the combustion volume, and NO... x With low emissions, it can effectively implement low-carbon operation.

[0029] In one embodiment, such as Figure 1 and Figure 5As shown, the pure ammonia burner 1 includes an ammonia pipe 11, a central air duct 12, an external secondary air sleeve 16, an airflow regulating blade 13, an airflow regulating device 14, and a drive device 15. One end of the ammonia pipe 11 is adapted to introduce ammonia gas, and one end of the central air duct 12 is connected to the ammonia pipe 11 through a first support member and embedded inside the ammonia pipe 11. The portion of the central air duct 12 embedded inside the ammonia pipe 11 extends along the length of the ammonia pipe 11 into the furnace. The central air duct 12 and the ammonia pipe 11 form an ammonia gas flow channel. The secondary air box 6 is connected, and the ammonia pipe 11 is installed on the outer secondary air sleeve 16 via a second support member, forming an outer secondary air duct. Airflow regulating blades 13 are welded to the outside of the ammonia pipe 11 and are used to generate rotating airflow. An airflow regulating device 14 is installed on the ammonia pipe 11 and connected to a drive device 15 such as an electric actuator. The airflow regulating device 14 adopts a conical disc structure, such as an air regulating disc, and is connected to the outer secondary air sleeve 16 to adjust the airflow entering the outer secondary air duct. This helps improve the completeness of ammonia combustion, further enhancing the effect of ammonia-blended combustion of lignite, lean coal, and other coal types, and further reducing NO₂ levels. x The emissions can meet the needs of deep peak-shaving operation of the boiler.

[0030] In this embodiment, the airflow regulating blades 13 are installed on the outer periphery of the ammonia pipe 11, forming a set of rotating blades in an outer ring to generate a rotating airflow, which helps to fully mix the air and ammonia. The drive device 15 is connected to the airflow regulating device 14 and is marked with its position. Moving the drive device 15 forward until it is in contact with the airflow regulating device 14, the airflow regulating device 14 is closed.

[0031] The air volume regulating device 14 adjusts the air volume entering the central air duct 12, and a stream of air is generated in the central air zone to penetrate deep into the furnace and mix with the flue gas. The drive device 15 is moved backward to the fully open position, the air volume regulating device 14 is turned on, and ammonia gas enters the ammonia gas flow channel from the ammonia gas pipe 11.

[0032] To further improve the completeness of fuel combustion and further reduce NO x Emissions, in one embodiment, such as Figure 1 and Figure 6As shown, the ammonia-coal co-fired burner 2 may include a primary air-coal duct 21, a light pulverized coal duct 22, a heavy pulverized coal duct 23, a central air duct 24, an annular ammonia duct 25, an ammonia connecting pipe 26, an ammonia-coal exhaust gas nozzle 28, an ammonia-coal concentration device 29, external secondary air fixed blades 210, external secondary air regulating blades 211, and internal secondary air fixed blades 212. One end of the primary air-coal duct 21 is suitable for introducing pulverized coal. The primary air-coal duct 21 is equipped with a light-light pulverized coal separator, which is used to separate pulverized coal into heavy pulverized coal and light pulverized coal. The light pulverized coal side of the light-light pulverized coal separator is connected to one end of the light pulverized coal duct 22, and the other end of the light pulverized coal duct 22 is equipped with an ammonia-coal exhaust gas nozzle. The heavy pulverized coal side of the light-light pulverized coal separator is connected to the heavy pulverized coal duct 23. A central air duct 24 is embedded within a concentrated pulverized coal duct 23 and connected via an internal support. The central air duct 24 and the concentrated pulverized coal duct 23 form an ammonia-coal flow channel. An annular ammonia duct 25 is installed outside the concentrated pulverized coal duct 23 and connected to the ammonia-coal flow channel via multiple ammonia connecting pipes 26. An ammonia-coal concentration device 29 is installed on the central air duct 24 and is used to uniformly disperse ammonia and pulverized coal. An inner secondary air sleeve is installed on the outside of the concentrated pulverized coal duct 23, forming an inner secondary air duct. An outer secondary air sleeve is installed on the outside of the inner secondary air sleeve, forming an outer secondary air duct. Outer secondary air fixed blades 210 and outer secondary air regulating blades 211 are arranged within the outer secondary air duct to regulate the swirl direction and intensity of the outer secondary air. Inner secondary air fixed blades 212 are arranged within the inner secondary air duct to regulate the swirl direction of the inner secondary air. This further enhances combustion.

[0033] In this embodiment, an annular ammonia pipe 25 may also be provided on the outer side of the pulverized coal pipe 22. The annular ammonia pipe 25 is connected to the ammonia-coal flow channel through multiple ammonia connecting pipes 26.

[0034] like Figure 6 As shown, the ammonia-coal co-fired burner 2 may further include a flow equalization device 27 installed within the pulverized coal pipeline 22. The flow equalization device 27 is used to disperse ammonia and pulverized coal. This further improves the completeness and stability of combustion, and helps reduce NO. x Emissions.

[0035] The ammonia-coal co-fired burner 2 has a main burner and a primary air-coal exhaust gas pipeline. A portion of the ammonia gas is fed into the primary air-coal exhaust gas pipeline (light coal pulverized gas pipeline 22) and transported to the furnace for combustion through the ammonia-coal exhaust gas nozzle. Another portion of the ammonia gas is transported to the primary air-coal pipeline 21 (dense coal pulverized gas pipeline 23) of the main burner and injected into the furnace for combustion through the outlet of the main burner.

[0036] The inlet of the ammonia-coal co-fired burner 2 is fed with pulverized coal through the primary air-coal pipe 21. After passing through the concentrated and dilute pulverized coal separator, the pulverized coal is separated into concentrated pulverized coal and dilute pulverized coal. The concentrated pulverized coal is mixed with ammonia and enters the furnace for combustion under the action of the central air and secondary air. The dilute pulverized coal is mixed with ammonia through the dilute pulverized coal pipe 22 and then enters the furnace for combustion.

[0037] Both the concentrated pulverized coal pipeline 23 and the dilute pulverized coal pipeline 22 are equipped with annular ammonia pipelines 25, and ammonia gas enters the concentrated and dilute pulverized coal pipelines 22 respectively through ammonia gas connecting pipes 26.

[0038] The ammonia-coal co-fired burner 2 has an ammonia-coal flow equalization device 27 embedded in the pulverized coal side air duct. An annular ammonia gas pipeline 25 is installed outside the pulverized coal pipeline 22 and is connected to the ammonia-coal duct through multiple ammonia gas connecting pipes 26. After passing through the ammonia-coal flow equalization device 27, the ammonia gas and pulverized coal are evenly dispersed and enter the furnace for combustion through the ammonia-coal exhaust gas nozzle.

[0039] Reference Figure 6 In one embodiment, the centerline of each ammonia connection pipe 26 forms a first angle with the centerline of the flow equalization device 27, with the opening facing away from the ammonia-coal exhaust gas nozzle 28. This first angle can be an acute angle. This helps to improve the uniformity of the mixing of light coal powder and ammonia.

[0040] Furthermore, the centerline of the ammonia connection pipe 26 and the centerline of the ammonia-coal concentration device 29 form a second angle with the opening towards the concentrated and diluted coal powder separator. This second angle can be acute. This helps to improve the uniformity of the mixing of concentrated coal powder and ammonia.

[0041] Preferably, the first included angle is 45° and the second included angle is 45°.

[0042] Reference Figures 1 to 4 In one embodiment, the ammonia-blended combustion system of the front and rear wall opposed boiler further includes an ammonia input pipe 5, which is arranged in a ring around the inner wall of the furnace and connected to the pure ammonia burner 1 and the ammonia-coal co-fired burner 2 respectively. In this way, ammonia can be conveniently delivered to each burner.

[0043] To further address the issues of poor combustion stability and NOx emissions when ammonia is blended into lignite, lean coal, and other coal types. x The problem of high emissions needs to be addressed by improving combustion completeness and reducing NO. x Emissions, implement low-carbon operation, refer to Figures 1 to 4In one embodiment, four layers of burners are arranged from top to bottom on the front and rear walls. The first layer from top to bottom is equipped with multiple pure ammonia burners 1, and each pure ammonia burner 1 is provided with a burnout air nozzle 4 above it. The second layer from top to bottom is equipped with multiple ammonia-coal co-fired burners 2. The third and fourth layers from top to bottom are equipped with multiple pulverized coal burners 3. Two or more pure ammonia burners 1 are arranged on the left and right walls at the same height as the first layer.

[0044] In this embodiment, two adjacent burnout air nozzles 4 along the length of the front and rear walls form a group, and the jet airflow directions of the two burnout air nozzles 4 in each group are opposite clockwise and counterclockwise and flow towards each other. For the first layer of burners, two adjacent pure ammonia burners 1 along the length of the front and rear walls form a group, and the outlet jet airflow directions of the two pure ammonia burners 1 in each group are opposite clockwise and counterclockwise and flow away from each other. For the second layer of burners, two adjacent ammonia-coal co-fired burners 2 along the length of the front and rear walls form a group, and the outlet jet airflow directions of the two ammonia-coal co-fired burners 2 in each group are opposite clockwise and counterclockwise and flow towards each other. For the third layer of burners, two adjacent pulverized coal burners 3 along the length of the front and rear walls form a group, and the outlet jet airflow directions of the two pulverized coal burners 3 in each group are opposite clockwise and counterclockwise and flow away from each other. For the fourth-layer burner, two adjacent pulverized coal burners 3 along the length of the front and rear walls form a group. The outlet jet airflow directions of the two pulverized coal burners 3 in each group are opposite (clockwise and counterclockwise) and flow towards each other. This arrangement significantly improves combustion effect and efficiency, effectively ensures combustion stability, and substantially reduces NO. x The emissions.

[0045] In practical applications, six burnout air nozzles 4 can be installed on the upper part of the front and rear walls of the furnace. Below the burnout air nozzles 4 on the front and rear walls, several pure ammonia burners 1, several ammonia-coal co-fired burners 2, and several pulverized coal burners 3 are arranged respectively. The front and rear walls each have four layers of burners, with six burners per layer, for a total of 48 burners. The uppermost layer of the furnace is the pure ammonia combustion zone, with six pure ammonia burners 1 arranged on the front and rear walls, for a total of 12. The second layer from top to bottom is the ammonia-coal co-fired zone, with six ammonia-coal co-fired burners 2 arranged on the front and rear walls, for a total of 12. The lower layers of the furnace (including the third and fourth layers) are the pulverized coal combustion zone, with 12 pulverized coal burners 3 arranged on the front and rear walls (six on each of the third and fourth layers), for a total of 24. The aforementioned pure ammonia burners 1 and ammonia-coal co-fired burners 2 are symmetrically arranged along the same center line on the front and rear walls. Simultaneously, two pure ammonia burners 1 can be arranged on the top layer of both the left and right walls, for a total of four. The secondary air for all the aforementioned ammonia-coal co-fired burners 2 and pure ammonia burners 1 comes from the secondary air box 6, while the wall-mounted air ducts 7 are separately arranged along the side walls. The ammonia inlets of the pure ammonia burners 1 distributed on the front and rear walls and the left and right side walls are respectively connected to the ammonia input pipes 5.

[0046] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An ammonia-laced combustion system for a front and back wall opposed boiler, characterized by, The application relates to a pure-ammonia combustion furnace. The furnace comprises a hearth which comprises a front wall, a left wall, a rear wall and a right wall which are connected in sequence, and a plurality of overfire air nozzles (4) are arranged on the front wall and the rear wall; a plurality of pure-ammonia burners (1), a plurality of ammonia-coal mixed combustion burners (2) and a plurality of coal powder burners (3) are arranged on the front wall and the rear wall below the overfire air nozzles (4) in sequence; and a plurality of the pure-ammonia burners (1) are arranged on the left wall and the right wall. The pure-ammonia burners (1) on the front wall and the pure-ammonia burners (1) on the rear wall are symmetrically arranged along the same center line; and / or the ammonia-coal mixed combustion burners (2) on the front wall and the ammonia-coal mixed combustion burners (2) on the rear wall are symmetrically arranged along the same center line. The pure-ammonia burner (1) comprises an ammonia gas pipe (11), a center air pipe (12), an outer secondary air sleeve (16), a wind volume adjusting blade (13), a wind volume adjusting device (14) and a driving device (15); one end of the ammonia gas pipe (11) is adapted to introduce ammonia gas; one end of the center air pipe (12) is connected with the ammonia gas pipe (11) through a first supporting piece and is embedded in the ammonia gas pipe (11); the part of the center air pipe (12) embedded in the ammonia gas pipe (11) extends into the hearth along the length direction of the ammonia gas pipe (11); the center air pipe (12) and the ammonia gas pipe (11) form an ammonia gas flow channel; the center air pipe (12) is communicated with a secondary air box (6); the ammonia gas pipe (11) is mounted on the outer secondary air sleeve (16) through a second supporting piece and forms an outer secondary air channel with the outer secondary air sleeve (16); the wind volume adjusting blade (13) is welded on the outer side of the ammonia gas pipe (11) and is used for generating rotating air flow; the wind volume adjusting device (14) is mounted on the ammonia gas pipe (11) and is connected with the driving device (15); the wind volume adjusting device is a conical disc type; the wind volume adjusting device (14) is connected with the outer secondary air sleeve (16) and is used for adjusting the wind volume entering the outer secondary air channel.

2. The ammonia slip pass-out boiler combustion system of claim 1, wherein, The ammonia-coal mixed combustion burner (2) comprises a primary air powder pipe (21), a light coal powder pipe (22), a dense coal powder pipe (23), a center air pipe (24), an annular ammonia gas pipe (25), an ammonia gas connecting pipe (26), an ammonia-coal exhaust gas air nozzle (28), an ammonia-coal concentration device (29), an outer secondary air fixed blade (210), an outer secondary air adjusting blade (211) and an inner secondary air fixed blade (212); 3. The ammonia slip catalyst system of claim 1, wherein the ammonia slip catalyst system is positioned in the furnace of the opposed wall boiler. One end of the primary air powder pipe (21) is adapted to introduce coal powder; the primary air powder pipe (21) is provided with a dense and light coal powder separator; the dense and light coal powder separator is used for separating the coal powder into dense coal powder and light coal powder; the light coal powder side of the dense and light coal powder separator is communicated with one end of the light coal powder pipe (22); the other end of the light coal powder pipe (22) is provided with an ammonia-coal exhaust gas nozzle; the dense coal powder side of the dense and light coal powder separator is communicated with the dense coal powder pipe (23). ​ The center air duct (24) is embedded in the dense coal duct (23) and connected by an inner support, the center air duct (24) and the dense coal duct (23) form an ammonia coal flow channel, the annular ammonia duct (25) is installed outside the dense coal duct (23) and connected to the ammonia coal flow channel through a plurality of ammonia connecting pipes (26), the ammonia coal concentration device (29) is installed on the center air duct (24) and used for uniformly dispersing ammonia and coal powder; An inner secondary air sleeve is installed outside the dense coal duct (23) and forms an inner secondary air channel, an outer secondary air sleeve is installed outside the inner secondary air sleeve and forms an outer secondary air channel; The outer secondary air fixed blade (210) and the outer secondary air adjusting blade (211) are arranged in the outer secondary air channel and used for adjusting the swirling direction and intensity of the outer secondary air, and the inner secondary air fixed blade (212) is arranged in the inner secondary air channel and used for adjusting the swirling direction of the inner secondary air.

4. The ammonia slip catalyst system of claim 3, wherein the ammonia slip catalyst system is positioned in the furnace of the opposed wall boiler. The ammonia coal mixed combustion burner (2) further comprises a flow uniformizing device (27) arranged in the dilute coal duct (22), and the flow uniformizing device (27) is used for dispersing ammonia and coal powder.

5. The ammonia slip catalyst system of claim 4, wherein the ammonia slip catalyst system is positioned in the furnace of the opposed wall boiler. The annular ammonia duct (25) is arranged on the outside of the dilute coal duct (22) and connected into the ammonia coal flow channel through a plurality of ammonia connecting pipes (26).

6. The ammonia slip catalyst system of claim 5, wherein the ammonia slip catalyst system is a front and back wall opposed boiler ammonia slip catalyst system. The center line of each ammonia connecting pipe (26) and the center line of the flow uniformizing device (27) form a first included angle with an opening facing away from the ammonia coal exhaust gas air jet (28), and the first included angle is an acute angle.

7. The ammonia slip catalyst system of claim 6, wherein the ammonia slip catalyst system is positioned in the furnace of the opposed wall furnace boiler. The center line of the ammonia connecting pipe (26) and the center line of the ammonia coal concentration device (29) form a second included angle with an opening facing the dense and dilute coal powder separator, and the second included angle is an acute angle.

8. The ammonia slip catalyst system of claim 7, wherein the ammonia slip catalyst system is a front and back wall opposed boiler ammonia slip catalyst system. The size of the first included angle is 45°; and / or, the size of the second included angle is 45°.

9. The ammonia slip catalyst system of claim 1, wherein the ammonia slip catalyst system is a front and back wall opposed boiler ammonia slip catalyst system. The ammonia mixing combustion system of the front and back wall opposing boiler further comprises an ammonia input duct (5), the ammonia input duct (5) is annularly arranged along the inner wall of the furnace and respectively communicated with the pure ammonia burner (1) and the ammonia coal mixed combustion burner (2).

10. The ammonia slip catalyst system of claim 1, wherein the ammonia slip catalyst system is a front and back wall opposed boiler ammonia slip catalyst system. The front wall and the back wall are arranged with four layers of burners from top to bottom, a plurality of pure ammonia burners (1) are arranged in the first layer, each pure ammonia burner (1) is provided with a burnout air jet (4) above, a plurality of ammonia coal mixed combustion burners (2) are arranged in the second layer, a plurality of coal powder burners (3) are arranged in the third layer and the fourth layer. The left wall and the right wall are provided with two or more pure ammonia burners (1) at the same height as the first layer.

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