Ammonia-coal mixed combustion burner

Abstract

The invention discloses an ammonia-coal mixed combustion burner, comprising: a plasma coal powder pre-combustion stage module, an ammonia two-stage combustion module, a coal powder main combustion stage module, and an air-graded secondary air module; in the plasma coal powder pre-combustion stage module, discharge is performed between electrodes to generate plasma, coal powder carried by primary air passes through a plasma fire core region to burn and generate a first coal powder flame, the first coal powder flame ignites ammonia fuel in the upstream of the ammonia two-stage combustion module to generate a stable ammonia-rich flame, combustion products and unburned reactants are mixed with air in the downstream of the ammonia two-stage combustion module to generate an ammonia-poor flame to heat the coal powder in the coal powder main combustion stage module to generate a second coal powder flame, and in the air-graded secondary air module, the secondary air is used to promote the full combustion of coal powder and ammonia, thereby realizing the stable combustion of the ammonia-coal mixed fuel, and effectively solving the problems of unstable combustion of ammonia coal and NO x Problems with excessive emissions and ammonia slip.

Description

Technical Field

[0001] The present invention relates to the field of combustion equipment and technology, and in particular to an ammonia-coal co-combustion burner, which is an ammonia-coal co-combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion. Background Art

[0002] Coal is one of the most important energy sources in my country, accounting for about 56% of the country's total energy consumption. However, the use of coal releases a large amount of pollutants and greenhouse gases, especially carbon dioxide (CO2). In 2022, carbon emissions from China's power generation industry accounted for 48% of the country's total emissions, and coal, as the main energy source for thermal power generation, is the main contributor to CO2 emissions. Therefore, there is an urgent need to find low-carbon alternative fuels to effectively reduce carbon emissions. Ammonia (NH3), as a new type of zero-carbon alternative fuel, has attracted widespread attention due to its high volumetric energy density, easy liquefaction, and low unit storage and transportation costs. Adding ammonia to coal-fired boilers for combustion can achieve low-carbon transformation from the fuel end, which is a carbon reduction approach with great potential.

[0003] However, the current clean and efficient combustion technology of ammonia fuel is not mature enough, and there are problems such as insufficient reactivity, difficulty in ignition, slow flame propagation speed, and the risk of unstable combustion during the co-combustion process. At the same time, ammonia contains a large amount of nitrogen, which will increase high NO when co-combusted with coal. x The emission risk and NO generated during combustion x It is extremely sensitive to the combustion environment. These problems need to be solved in the application of coal-fired boilers mixed with ammonia. Therefore, the development and design of advanced ammonia-coal mixed combustion burners are essential for maintaining stable fuel combustion and reducing NO x Emissions are important.

[0004] Patent CN115585449A discloses an invention patent application entitled "a new type of swirl burner suitable for direct mixed combustion of ammonia and coal powder". By setting an ammonia premixer, ammonia, coal powder and air are fully mixed in the primary air channel before entering the furnace, thereby reducing the difficulty of ammonia ignition. However, the above-mentioned burner directly mixes ammonia with coal powder airflow, which is likely to cause oxygen and ammonia to react first, which increases NO x The risks generated.

[0005] Patent CN117469676A discloses a method for the stable co-combustion of coal and ammonia with low NO xInvention patent application for "preheating combustion swirl burner", the burner is arranged radially from inside to outside in sequence as a central air sleeve, a primary air sleeve, an inner secondary air sleeve and an outer secondary air sleeve, wherein the primary air sleeve is used to transport coal powder and primary air, the inner secondary air sleeve contains a first-level ammonia passage pipe for transporting ammonia, and the reaction area in the combustion chamber is divided into a rich combustion area and a lean combustion area from inside to outside in the radial direction, the primary air and the inner secondary air are in the rich combustion area, and the outer secondary air is in the lean combustion area. The coal powder carried by the primary air enters the precombustion chamber, and after pre-decomposition, it sucks the ammonia introduced into the inner secondary air sleeve to strengthen the mixing of ammonia with coal powder and primary air, as well as the combustion of the fuel. However, in the above-mentioned burner, the ignition of coal powder as a stable combustion flame is relatively difficult, and the ignition of ammonia in the rich combustion area of ​​the furnace is also faced with high difficulty. The ammonia combustion adopts a central staged combustion mode, but the reaction of ammonia with flue gas and oxygen downstream of the rich combustion area may not be complete, which may easily lead to ammonia escape. Summary of the invention

[0006] In view of the above-mentioned problems in the design of ammonia-coal mixed combustion burner, the present invention provides an ammonia-coal mixed combustion burner, which is an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion, and proposes an ammonia-coal mixed combustion technology solution combining plasma combustion-assisted technology, staged combustion technology and ammonia-coal coordinated ignition combustion technology, which can effectively solve the problem of NO in ammonia-coal mixed combustion. x Problems include difficulty in controlling and difficulty in igniting coal powder and ammonia.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] An ammonia-coal co-combustion burner comprises a plasma pulverized coal pre-combustion stage module, an ammonia two-stage combustion module, a pulverized coal main combustion stage module and an air-staged secondary air module; the plasma pulverized coal pre-combustion stage module, the ammonia two-stage combustion module, the pulverized coal main combustion stage and the air-staged secondary air module are arranged radially from inside to outside; specifically, the plasma pulverized coal pre-combustion stage module and the ammonia two-stage combustion module adopt a concentric surround design, wherein the plasma pulverized coal pre-combustion stage module is located at the center, and the ammonia two-stage combustion module surrounds the outer side of the plasma pulverized coal pre-combustion stage module. The pulverized coal main combustion stage module is also distributed in a concentric structure outside the plasma pulverized coal pre-combustion stage module and the ammonia two-stage combustion module, and the air-graded secondary air module is located at the outermost layer of the concentric structure of the burner; the inlet ends of the plasma pulverized coal pre-combustion stage module, the ammonia two-stage combustion module, the pulverized coal main combustion stage module and the air-graded secondary air module are arranged in sequence from front to back along the axial direction, and the outlet end of the plasma pulverized coal pre-combustion stage module is located inside the ammonia two-stage combustion module, and the outlet ends of the ammonia two-stage combustion module, the pulverized coal main combustion stage module and the air-graded secondary air module are all connected to the inlet end of the furnace.

[0009] In the plasma pulverized coal pre-combustion stage module, discharge between electrodes generates plasma, and the pulverized coal carried by the primary air burns in the plasma fire core area to generate the first pulverized coal flame. The first pulverized coal flame ignites the upstream ammonia fuel in the ammonia two-stage combustion module to generate a stable ammonia-rich flame. The combustion products and unburned reactants are mixed with the downstream air in the ammonia two-stage combustion module to generate an ammonia-lean flame. The generated ammonia-lean flame is used as the duty flame to heat the pulverized coal in the pulverized coal main combustion stage module to generate the second pulverized coal flame, and finally the secondary air is used to promote the full combustion of the pulverized coal in the air-graded secondary air module.

[0010] Furthermore, the plasma pulverized coal pre-combustion stage module is composed of a first plasma generator, a first air channel, a first pulverized coal channel, a first nozzle, and a first pulverized coal flame. The first plasma generator is located upstream of the burner outlet end, and the first pulverized coal channel is located at the axial head and radial center of the plasma pulverized coal pre-combustion stage module; the first plasma generator adopts a sliding arc discharge structure, the working gas of the first plasma generator is the air transported by the first air channel, and the first pulverized coal channel is used to transport primary air and pulverized coal; the sliding arc discharge structure adopts a coaxial structure, which is mainly composed of a high-voltage electrode, a ground electrode, a nozzle and a ceramic cyclone ring. The high-voltage electrode and the ground electrode are kept fixed and coaxial by the ceramic cyclone ring, and the ceramic cyclone ring introduces the air to form a cyclone, and plasma is generated between the high-voltage electrode and the ground electrode; the first nozzle is located at the tail of the plasma pulverized coal pre-combustion stage module, and the primary air carries the pulverized coal through the plasma fire core area and is ejected through the first nozzle to generate the first pulverized coal flame.

[0011] Furthermore, the ammonia two-stage combustion module is composed of an ammonia-rich combustion zone, a concave cavity structure, a rapid mixing zone, and an ammonia-poor combustion zone, and the ammonia-rich combustion zone, the concave cavity structure, the rapid mixing zone, and the ammonia-poor combustion zone are arranged in sequence from front to back along the axial direction; the ammonia-rich combustion zone is composed of a first ammonia channel, a second tangential air channel, a second axial air channel, a first swirler, a second nozzle, and a first ammonia flame, and ammonia is introduced into the first ammonia channel, and air is introduced into the second tangential air channel and the second axial air channel respectively along the tangential and axial directions, so that in the air channel A cross-mixing is formed inside the cavity, and ammonia and air introduced generate a swirl after passing through the first cyclone. After the ammonia and air are mixed, they are ignited under the action of the first pulverized coal flame and ejected through the second nozzle to form a first ammonia flame, which is an ammonia-rich flame; the concave cavity structure is composed of an annular concave cavity structure shell, a first mixing chamber, a second ammonia channel, a third ammonia channel, a third air channel, a second plasma generator, a third nozzle, and a concave cavity ammonia flame. The second ammonia channel and the third ammonia channel are respectively located on the left and right sides of the concave cavity structure, and the third air channel is located at the concave cavity structure. The head of the cavity structure, the first mixing cavity is located at the center of the concave cavity structure, ammonia is introduced into the ammonia channel, and air is introduced into the air channel. The high temperature and active components generated by the second plasma generator ignite the ammonia-air mixture in the mixing cavity, and are ejected through the third nozzle to form a concave cavity ammonia flame. The concave cavity structure is provided with a contraction structure on the side close to the ammonia-rich combustion zone. After the air and fuel enter the second mixing cavity, they are fully mixed and sprayed into the burner to form a uniform combustion area to prevent flashback; the rapid mixing zone is composed of a fourth air channel, a fifth air channel, a plurality of air inflow holes and a second mixing cavity. Air is introduced into the fourth air channel and the fifth air channel respectively, and flows out from the air inflow holes, and is mixed with the products and unburned reactants generated in the ammonia-rich combustion zone in the second mixing cavity; the lean ammonia combustion zone is composed of a sixth air channel, a seventh air channel, a fourth nozzle and a second ammonia flame. Air is introduced into the sixth air channel and the seventh air channel for cooling the wall surface. The mixed gas flowing into the rapid mixing zone is ejected through the fourth nozzle to generate a second ammonia flame. The second ammonia flame is a lean ammonia flame, and the second ammonia flame is sprayed toward the furnace.

[0012] Furthermore, the pulverized coal main combustion stage module is composed of an eighth air channel, a second pulverized coal channel, a combustion stabilization chamber, a blunt body, a fifth nozzle and a second pulverized coal flame. The eighth air channel is used for heat exchange with the ammonia two-stage combustion module, and the second pulverized coal channel is used to transport primary air and pulverized coal. The airflow passes through the combustion stabilization chamber and the fifth nozzle, and a reflow zone is formed by the action of the blunt body. Finally, the second ammonia flame generated by the ammonia two-stage combustion module ignites the pulverized coal to form a second pulverized coal flame. The second pulverized coal flame is a pulverized coal-rich flame.

[0013] Furthermore, the air-graded secondary air module is composed of a ninth air channel, a sixth nozzle and a third pulverized coal flame. Air is introduced into the ninth air channel as secondary air, enters the burner axially, and is ejected through the sixth nozzle to assist the combustion of incompletely burned pulverized coal, promote complete combustion, and form a third pulverized coal flame. The third pulverized coal flame is a lean-burning pulverized coal flame. At the same time, the secondary air can also burn a very small amount of unburned ammonia to prevent ammonia escape.

[0014] Furthermore, the plasma pulverized coal pre-combustion stage module ignites part of the pulverized coal, and the generated first pulverized coal flame serves as the duty flame of the first ammonia flame in the ammonia two-stage combustion module, providing a large amount of heat source for the ignition of ammonia. At the same time, the volatile matter released releases a large amount of active free radicals (O, OH, H), thereby promoting the ignition and combustion reaction of ammonia.

[0015] Furthermore, the ammonia two-stage combustion module adopts rich-burn, rapid mixing and lean-burn technology. In the ammonia-rich combustion zone, due to the relatively low temperature and the small number of oxygen-containing intermediate products, the production of nitrogen oxides can be minimized; in the rapid mixing zone, there are multiple air inflow holes to increase the air jet momentum and increase the air jet depth, which is conducive to the rapid cross-mixing of air with the products and unburned reactants produced in the ammonia-rich combustion zone, and a second ammonia flame in the lean ammonia combustion zone.

[0016] Furthermore, the pulverized coal combustion adopts air classification technology, and the second ammonia flame is used as an ignition source to ignite the pulverized coal flame of the pulverized coal main combustion module to form a second pulverized coal flame. The second pulverized coal flame of the pulverized coal main combustion module forms a reducing atmosphere, which can effectively reduce the NO generated by ammonia combustion. x , while inhibiting the thermal and fuel-type NO generated by coal combustion x The air classification secondary air module assists the combustion of incompletely burned substances to achieve complete combustion.

[0017] The beneficial effects of the present invention are:

[0018] The present invention adopts plasma combustion-supporting technology to generate a stable first coal powder flame through a plasma coal powder pre-combustion module, providing heat and active free radicals for the ammonia-rich combustion zone in the ammonia two-stage combustion module. Under the action of the first coal powder flame and the strong swirl reflux zone, a stable first ammonia flame is formed. At the same time, the concave cavity structure in the ammonia two-stage combustion module forms a concave cavity ammonia flame, which further enhances the stability of the first ammonia flame. The ammonia two-stage combustion module adopts rich combustion, rapid mixing, and lean combustion technology, which can effectively reduce NO x The ammonia flame can also be used as a duty flame to provide heat and active components for the pulverized coal main combustion module. In addition, the pulverized coal main combustion module forms a reducing atmosphere, which further reduces the NO generated by ammonia combustion. x On the other hand, it effectively inhibits NO in the process of coal powder combustion.x This technology combines plasma combustion-assisted technology, staged combustion technology, and ammonia-coal coordinated ignition and combustion technology, which can not only solve the problems of low ammonia-coal combustion speed and ignition difficulty, but also effectively control the NO x Emissions and ammonia slip issues. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion of the present invention;

[0020] Figure 2 It is a schematic diagram of the principle of an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition and combustion of the present invention;

[0021] Figure 3 It is a side view of an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion of the present invention;

[0022] Figure 4 It is a three-dimensional cross-sectional view of an ammonia-coal mixed combustion burner according to the present invention based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition and combustion.

[0023] Markings in the figure: 1-plasma pulverized coal pre-combustion stage module, 2-ammonia two-stage combustion module, 3-pulverized coal main combustion stage module, 4-air classification secondary air module, 11-first plasma generator, 12-first air channel, 13-first pulverized coal channel, 14-first nozzle, 15-first pulverized coal flame, 21-ammonia-rich combustion zone, 22-concave cavity structure, 23-rapid mixing zone, 24-ammonia-poor combustion zone, 211-first ammonia channel, 212-second tangential air channel, 213-second axial air channel, 214-first swirler, 215-second nozzle, 216-first ammonia flame, 221-annular concave cavity structure shell, 222-first mixing chamber, 2 23-second ammonia channel, 224-third ammonia channel, 225-third air channel, 226-second plasma generator, 227-third nozzle, 228-concave cavity ammonia flame, 231-fourth air channel, 232-fifth air channel, 233-air inflow hole, 234-second mixing chamber, 241-sixth air channel, 242-seventh air channel, 243-fourth nozzle, 244-second ammonia flame, 31-eighth air channel, 32-second pulverized coal channel, 33-stable combustion chamber, 34-blunt body, 35-fifth nozzle, 36-second pulverized coal flame, 41-ninth air channel, 42-sixth nozzle, 43-third pulverized coal flame. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0026] like Figure 1 and 2 As shown, according to one embodiment of the present invention, an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion can be used in coal-fired boilers, industrial kilns and other fields. The ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion includes a plasma coal powder pre-combustion stage module 1, an ammonia two-stage combustion module 2, a coal powder main combustion stage module 3 and an air staged secondary air module 4.

[0027] like Figure 1 and 3 As shown, the plasma pulverized coal pre-combustion stage module 1, the ammonia two-stage combustion module 2, the pulverized coal main combustion stage 3 and the air-graded secondary air module 4 are arranged radially from inside to outside; specifically, the plasma pulverized coal pre-combustion stage module 1 and the ammonia two-stage combustion module 2 adopt a concentric surrounding design, wherein the plasma pulverized coal pre-combustion stage module 1 is located at the center, the ammonia two-stage combustion module 2 surrounds the outside of the plasma pulverized coal pre-combustion stage module 1, and the pulverized coal main combustion stage module 3 is also distributed in a concentric structure on the outside of the plasma pulverized coal pre-combustion stage module 1 and the ammonia two-stage combustion module 2, and the air-graded secondary air module 4 is located at the outermost layer of the concentric structure of the burner; the inlet ends of the plasma pulverized coal pre-combustion stage module 1, the ammonia two-stage combustion module 2, the pulverized coal main combustion stage module 3 and the air-graded secondary air module 4 are arranged in sequence from front to back along the axial direction, the outlet end of the plasma pulverized coal pre-combustion stage module 1 is located inside the ammonia two-stage combustion module 2, and the outlet ends of the ammonia two-stage combustion module 2, the pulverized coal main combustion stage module 3 and the air-graded secondary air module 4 are all connected to the inlet end of the furnace.

[0028] like Figure 2As shown, in the plasma pulverized coal pre-combustion module 1, discharge between electrodes generates plasma, and the pulverized coal carried by the primary air passes through the plasma fire core area to burn and generate the first pulverized coal flame 15. The first pulverized coal flame 15 ignites the upstream ammonia fuel in the ammonia two-stage combustion module 2 to generate a stable ammonia-rich flame. The combustion products and unburned reactants are mixed with the downstream air in the ammonia two-stage combustion module to generate an ammonia-lean flame. The generated ammonia-lean flame is used as a duty flame to heat the pulverized coal in the pulverized coal main combustion module 3 to generate a second pulverized coal flame 36, and finally the secondary air is used in the air-staged secondary air module 4 to promote the full combustion of the pulverized coal. In a preferred embodiment, the outlet ends of an ammonia-coal mixed combustion burner based on plasma combustion-assisted, staged combustion and ammonia-coal coordinated ignition combustion are arranged inside the furnace of a coal-fired boiler, and the direct injection flames of ammonia and pulverized coal help to more effectively transfer the thermal radiation of the flame to the water-cooled wall of the furnace of the coal-fired boiler, thereby improving the heat transfer efficiency.

[0029] like Figure 1 and 2 As shown, the plasma pulverized coal pre-combustion stage module 1 is composed of a first plasma generator 11, a first air channel 12, a first pulverized coal channel 13, a first nozzle 14, and a first pulverized coal flame 15. The first plasma generator 11 is located upstream of the burner outlet end, and the first pulverized coal channel 13 is located at the axial head of the plasma pulverized coal pre-combustion stage module 1, and the radial center position; the first plasma generator 11 adopts a sliding arc discharge structure, and the working gas of the first plasma generator is the air transported by the first air channel 12, and the first pulverized coal channel 13 is used to transport primary air and pulverized coal; in a preferred embodiment, the sliding arc discharge structure adopts a coaxial structure, which is mainly composed of a high-voltage electrode, a ground electrode, a nozzle and a ceramic cyclone ring. The high-voltage electrode and the ground electrode are fixed and coaxial through the ceramic cyclone ring, and the ceramic cyclone ring is introduced with the air to form a cyclone, and plasma is generated between the high-voltage electrode and the ground electrode; the first nozzle is located at the tail of the plasma pulverized coal pre-combustion stage module 1, and the primary air carries the pulverized coal through the plasma fire core area and is ejected through the first nozzle 14 to generate the first pulverized coal flame 15.

[0030] like Figure 1 and 2As shown, the ammonia two-stage combustion module 2 consists of an ammonia-rich combustion zone 21, a concave cavity structure 22, a rapid mixing zone 23, and an ammonia-poor combustion zone 24. The ammonia-rich combustion zone 21, the concave cavity structure 22, the rapid mixing zone 23, and the ammonia-poor combustion zone 24 are arranged in sequence from front to back along the axial direction; the ammonia-rich combustion zone 21 consists of a first ammonia channel 211, a second tangential air channel 212, a second axial air channel 213, a first swirler 214, a second nozzle 215, and a first ammonia flame 216. Ammonia is introduced into the first ammonia channel 211, and air is introduced into the second tangential air channel 212 and the second axial air channel 213 along the tangential and axial directions, respectively, so as to form a cross-mixing in the air channel. The introduced ammonia and air generate a swirl after passing through the first swirler 214. After the ammonia and air are mixed, they are ignited under the action of the first pulverized coal flame and ejected through the second nozzle 215 to form a first ammonia flame 216. The first ammonia flame 216 is an ammonia-rich flame. In a preferred embodiment, the first cyclone 214 can form a strong swirl recirculation zone for stabilizing the combustion of ammonia.

[0031] like Figure 1 and 2 As shown, the concave cavity structure 22 is composed of an annular concave cavity structure shell 221, a first mixing cavity 222, a second ammonia channel 223, a third ammonia channel 224, a third air channel 225, a second plasma generator 226, a third nozzle 227, and a concave cavity ammonia flame 228. The second ammonia channel 223 and the third ammonia channel 224 are respectively located on the left and right sides of the concave cavity structure 22, the third air channel 225 is located at the head of the concave cavity structure 22, and the first mixing cavity 222 is located at the center of the concave cavity structure 22. Ammonia is introduced into the ammonia channel, and air is introduced into the air channel. The high temperature and active components generated by the second plasma generator 226 ignite the ammonia-air mixture in the mixing cavity, and are ejected through the third nozzle 227 to form a concave cavity ammonia flame 228; in a preferred embodiment, the first pulverized coal flame 15 is used as a duty flame to provide sufficient heat for the first ammonia flame 216. At this time, the concave cavity ammonia flame 228 formed by the concave cavity structure can be selected not to be ignited.

[0032] like Figure 1 and 2 As shown, the rapid mixing zone 23 is composed of a fourth air channel 231, a fifth air channel 232, a plurality of air inlet holes 233 and a second mixing chamber 234. Air is introduced into the fourth air channel 231 and the fifth air channel 232 respectively, flows out from the air inlet holes 233, and is mixed with the products produced in the ammonia-rich combustion zone and unburned reactants in the second mixing chamber 234.

[0033] like Figure 1 and 2As shown, the ammonia-poor combustion zone 24 is composed of a sixth air channel 241, a seventh air channel 242, a fourth nozzle 243 and a second ammonia flame 244. Air is passed through the sixth air channel 241 and the seventh air channel 242 to cool the wall surface. The mixed gas flowing into the rapid mixing zone 23 is ejected through the fourth nozzle 243 to generate a second ammonia flame 244. The second ammonia flame 244 is an ammonia-poor flame, and the second ammonia flame 244 is sprayed toward the furnace.

[0034] like Figure 1 and 2 As shown, the pulverized coal main combustion stage module is composed of an eighth air channel 31, a second pulverized coal channel 32, a combustion stabilizing chamber 33, a blunt body 34, a fifth nozzle 35 and a second pulverized coal flame 36. The eighth air channel 31 is used for heat exchange with the ammonia two-stage combustion module 2, and the second pulverized coal channel 32 is used to transport primary air and pulverized coal. The airflow passes through the combustion stabilizing chamber 33 and the fifth nozzle 35, and a reflow zone is formed by the blunt body 34. Finally, the second ammonia flame 244 generated by the ammonia two-stage combustion module 2 ignites the pulverized coal to form a second pulverized coal flame 36. The second pulverized coal flame 36 is a pulverized coal-rich flame; as shown Figure 3 and 4 As shown, in a preferred embodiment, the bluff bodies 34 are circumferentially distributed along the outlet end of the main combustion stage module of the pulverized coal, and the number is 20. In some other embodiments, the bluff body 34 can be omitted, and the outer wall of the fourth nozzle is designed to be petal-shaped, so that the pulverized coal is sprayed from the fifth nozzle and a reflow zone is formed, thereby stabilizing the combustion of the pulverized coal.

[0035] like Figure 1 and 2 As shown, the air-classified secondary air module 4 is composed of a ninth air channel 41, a sixth nozzle 42 and a third pulverized coal flame 43. Air is introduced into the ninth air channel 41 as secondary air, enters the burner axially, and is ejected through the sixth nozzle 42 to assist the combustion of incompletely burned pulverized coal, promote full combustion, and form the third pulverized coal flame 43. The third pulverized coal flame 43 is a pulverized coal lean combustion flame. At the same time, the secondary air can also burn a very small amount of unburned ammonia to prevent ammonia from escaping.

[0036] like Figure 2 As shown, the plasma pulverized coal pre-combustion stage module 1 ignites part of the pulverized coal, and the generated first pulverized coal flame 15 serves as the duty flame of the first ammonia flame 216 in the ammonia two-stage combustion module 2, providing a large amount of heat source for the ignition of ammonia. At the same time, the volatile matter released releases a large amount of active free radicals (O, OH, H), thereby promoting the ignition and combustion reaction of ammonia.

[0037] like Figure 2As shown, the ammonia two-stage combustion module 2 adopts rich combustion, rapid mixing and lean combustion technology. In the ammonia-rich combustion zone 21, due to the relatively low temperature and the small number of oxygen-containing intermediate products, the generation of nitrogen oxides can be minimized; in the rapid mixing zone 23, there are multiple air inflow holes to increase the air jet momentum and increase the air jet depth, which is beneficial to the rapid cross-mixing of air with the products and unburned reactants generated in the ammonia-rich combustion zone 21, and a second ammonia flame is generated in the lean ammonia combustion zone 24.

[0038] like Figure 2 As shown, the pulverized coal combustion adopts air classification technology, and the second ammonia flame 244 is used as an ignition source to ignite the pulverized coal flame of the pulverized coal main combustion module 3 to form a second pulverized coal flame 36. The second pulverized coal flame 36 of the pulverized coal main combustion module 3 forms a reducing atmosphere, which can effectively reduce the NOx generated by ammonia combustion and suppress the thermal and fuel NOx generated by pulverized coal combustion. The air classification secondary air module 4 assists in the combustion of incompletely burned substances to achieve complete combustion.

Claims

1. An ammonia-coal co-combustion burner, characterized in that: Included are: A plasma coal powder pre-combustion module (1), an ammonia two-stage combustion module (2), a coal powder main combustion module (3) and an air classification secondary air module (4); The plasma pulverized coal pre-combustion stage module (1), the ammonia two-stage combustion module (2), the pulverized coal main combustion stage module (3) and the air classification secondary air module (4) are arranged radially from the inside to the outside; the plasma pulverized coal pre-combustion stage module (1) and the ammonia two-stage combustion module (2) adopt a concentric surrounding design, wherein the plasma pulverized coal pre-combustion stage module (1) is located at the center, the ammonia two-stage combustion module (2) surrounds the outside of the plasma pulverized coal pre-combustion stage module (1), and the pulverized coal main combustion stage module (3) is also distributed in the plasma pulverized coal pre-combustion stage module (1) and the ammonia two-stage combustion module (2) in a concentric structure. The plasma pulverized coal pre-combustion module (1) is located outside the ammonia two-stage combustion module (2), and the air-classified secondary air module (4) is located at the outermost layer of the concentric structure of the burner; the inlet ends of the plasma pulverized coal pre-combustion module (1), the ammonia two-stage combustion module (2), the pulverized coal main combustion module (3) and the air-classified secondary air module (4) are arranged in sequence from front to back along the axial direction, the outlet end of the plasma pulverized coal pre-combustion module (1) is located inside the ammonia two-stage combustion module (2), and the outlet ends of the ammonia two-stage combustion module (2), the pulverized coal main combustion module (3) and the air-classified secondary air module (4) are all connected to the inlet end of the furnace; In the plasma pulverized coal pre-combustion module (1), discharge occurs between electrodes to generate plasma, pulverized coal carried by the primary air passes through the plasma fire core region and burns to generate a first pulverized coal flame (15), the first pulverized coal flame (15) ignites the ammonia fuel in the middle and upstream of the ammonia two-stage combustion module (2) to generate a stable ammonia-rich flame, the combustion products and unburned reactants are mixed with the air in the middle and downstream of the ammonia two-stage combustion module to generate an ammonia-poor flame, the generated ammonia-poor flame is used as a duty flame to heat the pulverized coal in the pulverized coal main combustion module (3), and a second pulverized coal flame (36) is generated, and finally the secondary air in the air classification secondary air module (4) promotes the full combustion of pulverized coal and ammonia.

2. The ammonia-coal co-firing burner according to claim 1, characterized in that: The plasma coal powder pre-combustion stage module (1) is composed of a first plasma generator (11), a first air channel (12), a first coal powder channel (13), a first nozzle (14), and a first coal powder flame (15); the first plasma generator (11) is located upstream of the burner outlet end; the first coal powder channel (13) is located at the axial head of the plasma coal powder pre-combustion stage module (1) and at the radial center position; the first plasma generator (11) adopts a sliding arc discharge structure; the working gas of the first plasma generator is transported by the first air channel (12); The first pulverized coal channel (13) is used to transport primary air and pulverized coal; the sliding arc discharge structure adopts a coaxial structure, mainly consisting of a high-voltage electrode, a ground electrode, a nozzle and a ceramic cyclone ring; the high-voltage electrode and the ground electrode are fixed and coaxial through the ceramic cyclone ring; the ceramic cyclone ring is introduced with the air to form cyclone gas, and plasma is generated between the high-voltage electrode and the ground electrode; the first nozzle is located at the rear of the plasma pulverized coal pre-combustion stage module (1); the primary air carries the pulverized coal through the plasma fire core area and is ejected through the first nozzle (14) to generate a first pulverized coal flame (15).

3. The ammonia-coal co-firing burner according to claim 1, characterized in that: The ammonia two-stage combustion module (2) is composed of an ammonia-rich combustion zone (21), a cavity structure (22), a rapid mixing zone (23), and an ammonia-poor combustion zone (24), wherein the ammonia-rich combustion zone (21), the cavity structure (22), the rapid mixing zone (23), and the ammonia-poor combustion zone (24) are arranged in sequence from front to back along the axial direction; the ammonia-rich combustion zone is composed of a first ammonia channel (211), a second tangential air channel (212), a second axial air channel (213), a first swirler (214), a second nozzle (215), and a first ammonia The first ammonia channel (211) is used to introduce ammonia, and the second tangential air channel (212) and the second axial air channel (213) are used to introduce air in the tangential and axial directions, respectively, so that cross mixing is formed in the air channel. The introduced ammonia and air generate a swirl after passing through the first cyclone (214). The ammonia and air are mixed and ignited under the action of the first pulverized coal flame, and are ejected through the second nozzle (215) to form a first ammonia flame (216). The first ammonia flame (216) is an ammonia-rich flame. The concave cavity structure (22) is composed of an annular concave cavity structure shell (221), a first mixing cavity (222), a second ammonia channel (223), a third ammonia channel (224), a third air channel (225), a second plasma generator (226), a third nozzle (227), and a concave cavity ammonia flame (228); the second ammonia channel (223) and the third ammonia channel (224) are respectively located on the left and right sides of the concave cavity structure (22); the third air channel (225) is located at the head of the concave cavity structure (22); the first mixing cavity (222) is located at the center of the concave cavity structure (22); ammonia is introduced into the ammonia channel, and air is introduced into the air channel; the high temperature and active components generated by the second plasma generator (226) ignite the ammonia-air mixture in the mixing cavity, and the mixture is ejected through the third nozzle (227) to form a concave cavity ammonia flame (228); The rapid mixing zone (23) is composed of a fourth air channel (231), a fifth air channel (232), a plurality of air inflow holes (233) and a second mixing chamber (234); air is introduced into the fourth air channel (231) and the fifth air channel (232) respectively, flows out from the air inflow holes (233), and is mixed with products generated in the ammonia-rich combustion zone and unburned reactants in the second mixing chamber (234); The ammonia-poor combustion zone (24) is composed of a sixth air channel (241), a seventh air channel (242), a fourth nozzle (243) and a second ammonia flame (244). Air is introduced into the sixth air channel (241) and the seventh air channel (242) to cool the wall surface. The mixed gas flowing into the fast mixing zone (23) is ejected through the fourth nozzle (243) to generate a second ammonia flame (244). The second ammonia flame (244) is an ammonia-poor flame. The second ammonia flame (244) is ejected toward the furnace.

4. The ammonia-coal co-combustion burner according to claim 3, characterized in that: The ammonia two-stage combustion module (2) adopts rich combustion, rapid mixing and lean combustion technology. In the ammonia-rich combustion zone (21), the temperature is relatively low and the number of oxygen-containing intermediate products is small, which can minimize the generation of nitrogen oxides. In the rapid mixing zone (23), there are multiple air inflow holes to increase the air jet momentum and increase the air jet depth, which is conducive to the rapid cross-mixing of air with the products and unburned reactants generated in the ammonia-rich combustion zone (21), and a second ammonia flame is generated in the lean ammonia combustion zone (24).

5. The ammonia-coal co-firing burner according to claim 3, characterized in that: The plasma pulverized coal pre-combustion module (1) ignites part of the pulverized coal, and the generated first pulverized coal flame (15) serves as the duty flame of the first ammonia flame (216) in the ammonia two-stage combustion module (2), providing a heat source for the ignition of the ammonia. At the same time, the volatile matter released releases active free radicals, thereby promoting the ignition and combustion reaction of the ammonia.

6. The ammonia-coal co-firing burner according to claim 1, characterized in that: The pulverized coal main combustion module is composed of an eighth air channel (31), a second pulverized coal channel (32), a combustion stabilization chamber (33), a blunt body (34), a fifth nozzle (35) and a second pulverized coal flame (36). The eighth air channel (31) is used for heat exchange with the ammonia two-stage combustion module (2). The second pulverized coal channel (32) is used for conveying primary air and pulverized coal. The airflow passes through the combustion stabilization chamber (33) and the fifth nozzle (35), and a reflow zone is formed through the action of the blunt body (34). Finally, the second ammonia flame (244) generated by the ammonia two-stage combustion module (2) ignites the pulverized coal to form a second pulverized coal flame (36). The second pulverized coal flame (36) is a pulverized coal rich combustion flame.

7. The ammonia-coal co-firing burner according to claim 1, characterized in that: The air classification secondary air module (4) is composed of a ninth air channel (41), a sixth nozzle (42) and a third pulverized coal flame (43). Air is introduced into the ninth air channel (41) as secondary air, enters the burner axially, and is ejected through the sixth nozzle (42) to assist combustion of incompletely burned pulverized coal, promote full combustion, and form a third pulverized coal flame (43). The third pulverized coal flame (43) is a pulverized coal lean combustion flame. At the same time, the secondary air can also burn unburned ammonia to prevent ammonia escape.

8. The ammonia-coal co-firing burner according to claim 7, characterized in that: The pulverized coal combustion adopts air classification technology, and the second ammonia flame (244) is used as the duty flame to ignite the pulverized coal flame of the pulverized coal main combustion module (3) to form a second pulverized coal flame (36); the second pulverized coal flame (36) of the pulverized coal main combustion module (3) forms a reducing atmosphere, which can reduce the NOx generated by the combustion of ammonia and suppress the thermal and fuel NOx generated by the combustion of pulverized coal; the air classification secondary air module (4) assists in the combustion of incompletely burned substances to achieve complete combustion.

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