Fire coal and hydrogen mixed combustion boiler system and combustion method for mixed combustion of hydrogen in coal-fired boiler

Abstract

The invention relates to the technical field of mixed combustion of hydrogen, and discloses a coal-fired and hydrogen mixed combustion boiler system and a combustion method for mixed combustion of hydrogen in a coal-fired boiler, the coal-fired and hydrogen mixed combustion boiler system comprises a boiler body, a pulverized coal combustion unit, a hydrogen combustion unit, a first air pipe assembly and a second air pipe assembly; a main combustion area is arranged in the boiler body; the pulverized coal combustion unit comprises a first combustion assembly, one end of the first combustion assembly is connected with the main combustion area, and the two ends of the first combustion assembly are connected with a first air pipe assembly and a second air pipe assembly correspondingly. The hydrogen combustion unit is arranged below the pulverized coal combustion unit and comprises a hydrogen pipeline, a mixing chamber and a second combustion assembly, one end of the second combustion assembly is connected with the main combustion area, the other end of the second combustion assembly is connected with the mixing chamber, and the two ends of the mixing chamber are connected with the hydrogen pipeline and the second air pipe assembly respectively.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen blending, and in particular to a coal-hydrogen mixed combustion boiler system and a coal-fired boiler hydrogen blending combustion method. Background Art

[0002] One of the ways to reduce carbon dioxide emissions from coal-fired boilers is to burn low-carbon or zero-carbon fuels. Hydrogen produced from renewable energy is a globally recognized fuel with zero carbon emissions. By burning hydrogen in a coal-fired boiler at a certain ratio, hydrogen can replace part of the coal while the total output energy remains unchanged, which can reduce carbon dioxide emissions from the source.

[0003] At present, coal-fired boilers are mainly designed according to the combustion characteristics of coal. If there are large differences in the characteristics of the input fuel, it will affect the safe operation of the boiler. Burners that burn pure hydrogen have been developed at home and abroad. Since hydrogen ignites quickly, the burner needs to be designed with a very high hydrogen outlet velocity to prevent flame flashback or nozzle overheating. According to the literature, the outlet velocity of the hydrogen burner must reach 200m / s, which is much higher than the design speed of the coal-fired boiler burner, which easily causes the problem of interference between the flow fields of the two adjacent burners. In addition, hydrogen combustion has the characteristics of high local flame temperature and weak radiation. When a boiler designed for coal burning is mixed with hydrogen in a large proportion, it is easy to cause local overheating of the boiler, causing excessive nitrogen oxides and overheating of the heating surface in the furnace. Summary of the invention

[0004] The technical problem to be solved by the present invention is that in the prior art, when a large amount of hydrogen is mixed into a coal-fired boiler, it is easy to cause local overheating of the boiler, causing excessive nitrogen oxides and overheating of the heating surface in the furnace.

[0005] In order to solve the above technical problems, the present invention provides a coal and hydrogen mixed combustion boiler system, which includes a boiler body, a pulverized coal combustion unit, a hydrogen combustion unit, a first air duct assembly and a second air duct assembly; a main combustion area is arranged inside the boiler body, and the smoke flows from bottom to top in the main combustion area; the pulverized coal combustion unit includes a first combustion assembly, one end of the first combustion assembly is connected to the main combustion area, and the two ends of the first combustion assembly are respectively connected to the first air duct assembly and the second air duct assembly; the hydrogen combustion unit is arranged below the pulverized coal combustion unit, the hydrogen combustion unit includes a hydrogen pipeline, a mixer and a second combustion assembly, one end of the second combustion assembly is connected to the main combustion area, and the other end is connected to the mixer, and the two ends of the mixer are respectively connected to the hydrogen pipeline and the second air duct assembly.

[0006] In one embodiment, the pulverized coal combustion unit further includes a first nozzle, and the number of the first nozzles and the first combustion assembly is multiple, one end of each first nozzle is connected to the main combustion area, and the other end of each first nozzle is connected to the first combustion assembly.

[0007] In one embodiment, the second air duct assembly includes a main pipe, a first branch pipe and a secondary air box, one end of the first branch pipe is connected to the main pipe, and the other end is connected to the first combustion assembly, the number of secondary air boxes is the same as the number of first combustion assemblies, one end of each secondary air box is connected to the first combustion assembly, and the other end is connected to the first branch pipe.

[0008] In one embodiment, it further includes a burnout zone unit, which is arranged above the pulverized coal combustion unit, one end of the burnout zone unit is connected to the main combustion area, and the other end is connected to the second air duct assembly.

[0009] In one embodiment, the burnout zone unit includes multiple second nozzles, and the second air duct assembly also includes a second branch pipe, one end of the second branch pipe is connected to the second branch pipe, and the other end of the second branch pipe is respectively connected to the multiple second nozzles, and the second branch pipe injects air into the main combustion area through the second nozzle.

[0010] In one embodiment, the second air duct assembly further includes a third branch pipe, which is disposed below the main pipe, one end of the third branch pipe is connected to the main pipe, and the other end of the third branch pipe is connected to the mixing chamber for injecting air into the mixing chamber.

[0011] In order to solve the above technical problems, the present invention provides a combustion method for a coal-fired boiler mixed with hydrogen, which adopts the above-mentioned coal-fired and hydrogen mixed combustion boiler system, injects air into the main combustion zone through a first air duct assembly; and simultaneously injects air into the hydrogen combustion unit through a second air duct assembly, and the air injected into the hydrogen combustion unit is mixed with hydrogen and then passed into the second combustion assembly.

[0012] In one embodiment, the hydrogen combustion unit is located below the pulverized coal combustion unit, upstream from the direction of flue gas flow, and the hydrogen combustion unit and the pulverized coal combustion unit are far away from each other.

[0013] In one embodiment, the hydrogen in the hydrogen combustion unit is mixed with air in a mixing chamber, and the first stage combustion of hydrogen is performed on the side of the main combustion area close to the hydrogen combustion unit, and the unburned hydrogen continues to be mixed with coal powder on the side of the main combustion area close to the coal powder combustion unit for the second stage combustion operation.

[0014] In one embodiment, hydrogen and pulverized coal are subjected to a third stage combustion operation at one side of the main combustion area close to the burnout zone unit.

[0015] The embodiment of the present invention provides a coal-hydrogen mixed combustion boiler system and a coal-fired boiler combustion method for mixing hydrogen. Compared with the prior art, the beneficial effects are as follows: 1) a pulverized coal combustion unit, the pulverized coal combustion unit comprises a first combustion assembly, one end of which is connected to the main combustion area, and the two ends of the first combustion assembly are respectively connected to the first air duct assembly and the second air duct assembly. The two air duct assemblies are used to provide ignition air and air for regulating the combustion process to the coal powder twice to optimize the combustion process; 2) Hydrogen combustion unit, the hydrogen combustion unit is located below the coal powder combustion unit. This design helps to avoid interference between the flow fields of the two combustion units due to different wind speeds. The hydrogen combustion unit includes a hydrogen pipeline, a mixer and a second combustion assembly. The hydrogen pipeline is responsible for providing hydrogen to the mixing chamber, and the mixer is used to evenly mix the hydrogen with the air injected by the second air duct assembly. One end of the second combustion assembly is connected to the main combustion area, and the other end is connected to the mixer to ensure that the evenly mixed hydrogen-air mixture can have sufficient oxygen to ignite in the main combustion area, but the chemical equivalence is less than 1, which suppresses the hydrogen combustion rate and avoids high temperature. After the partially burned hydrogen and its combustion products enter the main combustion area, they form a dual-fuel coupling area with the coal powder. This area is still in an oxygen-deficient state, while satisfying the hydrogen combustion and coal powder ignition, it still maintains the inhibitory effect on the generation of nitrogen oxides. The present invention effectively solves the problem in the prior art that when a large amount of hydrogen is mixed into a coal-fired boiler, it is easy to cause local overheating of the boiler, causing excessive nitrogen oxides and overheating of the heating surface in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a coal-hydrogen mixed combustion boiler system according to an embodiment of the present invention.

[0017] Figure 2 It is a structural schematic diagram of a pulverized coal combustion unit according to an embodiment of the present invention.

[0018] In the figure, 1. boiler body; 11. main combustion area; 2. pulverized coal combustion unit; 21. first combustion assembly; 22. first nozzle; 3. hydrogen combustion unit; 31. hydrogen pipeline; 32. mixing chamber; 33. second combustion assembly; 4. first air duct assembly; 5. second air duct assembly; 51. main pipe; 52. first branch pipe; 53. secondary air box; 54. second branch pipe; 55. third branch pipe; 6. burnout zone unit; 61. second nozzle. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] In the description of the present invention, it should be understood that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0021] In the description of the present invention, it should be understood that the terms "height", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] In the description of the present invention, it should be understood that the terms "first" and "second" are used in the present invention for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0023] like Figure 1 to Figure 2 As shown, an embodiment of the present invention preferably provides a coal-fired and hydrogen mixed combustion boiler system, which includes a boiler body 1, a pulverized coal combustion unit 2, a hydrogen combustion unit 3, a first air duct assembly 4 and a second air duct assembly 5; a main combustion area 11 is arranged inside the boiler body 1, and the flue gas in the main combustion area 11 flows from bottom to top; the pulverized coal combustion unit 2 includes a first combustion assembly 21, one end of the first combustion assembly 21 is connected to the main combustion area 11, and the two ends of the first combustion assembly 21 are respectively connected to the first air duct assembly 4 and the second air duct assembly 5; the hydrogen combustion unit 3 is arranged below the pulverized coal combustion unit 2, the hydrogen combustion unit 3 includes a hydrogen pipeline 31, a mixing chamber 32 and a second combustion assembly 33, one end of the second combustion assembly 33 is connected to the main combustion area 11, and the other end is connected to the mixing chamber 32, and the two ends of the mixing chamber 32 are respectively connected to the hydrogen pipeline 31 and the second air duct assembly 5.

[0024] Based on the above technical features, the present invention is provided with a pulverized coal combustion unit 2, and the pulverized coal combustion unit 2 includes a first combustion component 21, one end of which is connected to the main combustion area 11, ensuring that the heat generated by the first combustion component 21 can be directly transferred to the boiler body 1, and the two ends of the first combustion component 21 are respectively connected to the first air duct component 4 and the second air duct component 5. The two air duct assemblies are used to provide air to the first combustion assembly 21 twice or adjust the airflow in the combustion assembly to optimize the combustion process; through the setting of the hydrogen combustion unit 3, the hydrogen combustion unit 3 is located below the pulverized coal combustion unit 2. This design helps to avoid the two combustion units from interfering with each other due to different wind speeds. The hydrogen combustion unit 3 includes a hydrogen pipeline 31, a mixing chamber 32 and a second combustion assembly 33. The hydrogen pipeline 31 is responsible for providing hydrogen to the mixing chamber 32, and the mixing chamber 32 is used to mix the hydrogen with the air injected by the second air duct assembly 5. One end of the second combustion assembly 33 is connected to the main combustion area 11, and the other end is connected to the mixing chamber 32 to ensure that the evenly mixed hydrogen-air mixture can be efficiently burned in the main combustion area 11. After the burned hydrogen and its combustion products enter the main combustion area, a dual-fuel coupling area is formed, which can satisfy the hydrogen combustion while still maintaining the inhibitory effect on the generation of nitrogen oxides.

[0025] As some embodiments of the present invention, Figure 1 to Figure 2 As shown, the pulverized coal combustion unit 2 also includes a first nozzle 22. The number of the first nozzle 22 and the first combustion assembly 21 is multiple. One end of each first nozzle 22 is connected to the main combustion area 11, and the other end of each first nozzle 22 is connected to the first combustion assembly 21. The multiple first nozzles 22 and the multiple first combustion assemblies 21 in the pulverized coal combustion unit 2 work together to achieve full mixing and efficient combustion of pulverized coal and air. This design not only improves the thermal energy output and combustion efficiency of the boiler, but also helps to reduce the emission of pollutants. In actual applications, the number and layout of the first nozzles 22 can be adjusted according to the scale of the boiler body and the combustion requirements to achieve the best combustion effect.

[0026] As some embodiments of the present invention, Figure 1 to Figure 2 As shown, the second air duct assembly 5 includes a main pipe 51, a first branch pipe 52 and a secondary air box 53. One end of the first branch pipe 52 is connected to the main pipe 51, and the other end is connected to the first combustion assembly 21. The number of the secondary air boxes 53 is the same as the number of the first combustion assembly 21. One end of each secondary air box 53 is connected to the first combustion assembly 21, and the other end is connected to the first branch pipe 52. The second air duct assembly 5 includes the main pipe 51, the first branch pipe 52 and the secondary air box 53, which work together to realize the secondary injection of combustion-supporting air into the pulverized coal combustion unit 2. This design not only improves the combustion efficiency of the pulverized coal combustion unit 2, but also helps to reduce the emission of pollutants.

[0027] As some embodiments of the present invention, Figure 1 to Figure 2 As shown, it also includes a burnout zone unit 6, which is arranged above the pulverized coal combustion unit 2, one end of the burnout zone unit 6 is connected to the main combustion area 11, and the other end is connected to the second air duct assembly 5. The main function of the burnout zone unit 6 is to ensure that the pulverized coal can continue to burn after the main combustion area 11 until it is completely burned, which helps to reduce the unburned carbon content in the boiler body emissions and improve the combustion efficiency of the boiler body.

[0028] As some embodiments of the present invention, Figure 1 to Figure 2 As shown, the burnout zone unit 6 includes a plurality of second nozzles 61, and the second air duct assembly 5 also includes a second branch pipe 54, one end of the second branch pipe 54 is connected to the second branch pipe 54, and the other end of the second branch pipe 54 is respectively connected to the plurality of second nozzles 61, and the second branch pipe 54 injects air into the main combustion area 11 through the second nozzles 61. Through the arrangement of the second branch pipe 54, the combustion-supporting air in the second air duct assembly 5 is injected into the main body through the second nozzle 61, and the air can provide additional oxygen for the combustion of the boiler main body, support the continued combustion of the pulverized coal, and help bring the unburned pulverized coal particles into a more complete combustion environment.

[0029] As some embodiments of the present invention, Figure 1 to Figure 2 As shown, the second air duct assembly 5 also includes a third branch pipe 55, which is arranged below the main pipe 51, one end of the third branch pipe 55 is connected to the main pipe 51, and the other end of the third branch pipe 55 is connected to the mixing chamber 32 for injecting air into the mixing chamber 32. The mixing chamber 32 is used for the preliminary mixed combustion of hydrogen and air. The air injected into the mixing chamber 32 by the third branch pipe 55 makes the hydrogen and air in the hydrogen combustion unit 3 mixed in the mixing chamber 32. This part of air provides the necessary combustion conditions for hydrogen. The hydrogen enters the second combustion assembly for the first stage of hydrogen combustion, and the hydrogen after the first stage of combustion enters the main combustion area 11 for the second combustion.

[0030] As some embodiments of the present invention, the main combustion area 11 includes an initial combustion area and a flame area arranged in sequence from bottom to top. According to the proportion of hydrogen blending, on the one hand, hydrogen remains in a fuel-rich state after entering the flame area from the initial combustion area, and can form a reducing gas that inhibits the generation of nitrogen oxides. Therefore, the amount of oxygen in the flame area will not increase the generation of nitrogen oxides. On the other hand, hydrogen will quickly consume part of the oxygen in the area. When the pulverized coal enters the center of the flame area, it is still in a reducing gas state that inhibits the generation of nitrogen oxides. Hydrogen and pulverized coal form a dual-fuel reduction zone coupling in the flame area. While inhibiting the generation of nitrogen oxides, it also alleviates the efficiency of oxygen combustion caused by the rapid combustion of hydrogen, so that the pulverized coal is burned out in an atmosphere of excess oxygen.

[0031] The present invention also provides a method for burning hydrogen in a coal-fired boiler, using the above-mentioned coal-and-hydrogen mixed combustion boiler system, by opening the first air duct assembly 4, the first air duct assembly 4 injects air into the pulverized coal combustion unit 2 for the first time, the injected air is mixed with the pulverized coal in advance and injected into the first combustion assembly 21; after the air-pulverized coal mixed gas in the first combustion assembly 21 is burned, the second air duct assembly 5 is opened, the second air duct assembly 5 injects air into the pulverized coal combustion unit 2 for the second time, and at the same time the second air duct assembly 5 injects air into the hydrogen combustion unit 3, the injected air is mixed with hydrogen in advance, the mixed air and hydrogen are passed into the second combustion assembly, and burned in the second combustion assembly.

[0032] As some embodiments of the present invention, the hydrogen combustion unit 3 is located below the pulverized coal combustion unit 2, and the hydrogen combustion unit 3 and the pulverized coal combustion unit 2 are far away from each other, so as to effectively avoid mutual interference of the flow fields of the two combustion units due to different wind speeds.

[0033] Furthermore, the hydrogen combustion unit 3 is located below the pulverized coal combustion unit 2 and is upstream from the direction of flue gas flow.

[0034] As some embodiments of the present invention, the hydrogen in the hydrogen combustion unit 3 is mixed with air in the mixing chamber 32, and the first stage of hydrogen combustion operation is carried out on the side of the main combustion area 11 close to the hydrogen combustion unit 3, and the unburned hydrogen continues to mix with the pulverized coal on the side of the main combustion area 11 close to the pulverized coal combustion unit 2 for the second stage of combustion operation. The hydrogen in the hydrogen combustion unit 3 is mixed with hydrogen and air in the mixer 32, and the mixed air is less than the chemical equivalent 1 (0.3-0.8), that is, the mixed air cannot support the complete combustion of hydrogen, and only part of the hydrogen burns first, thereby avoiding the high temperature and large-scale generation of nitrogen oxides caused by the excessive combustion of hydrogen. The unburned hydrogen is mixed with the pulverized coal in the pulverized coal combustion unit 2 for combustion, and the air distribution strategy adopted by the pulverized coal unit 2 is different from that of conventional coal-fired boilers. Conventional pulverized coal boilers are configured with an air chemical equivalent of 0.7-0.75 for the first stage of pulverized coal combustion, and a lower equivalent will result in unstable ignition of pulverized coal and incomplete combustion. The pulverized coal combustion unit 2 of the present invention takes into account the coupling of the first-stage combustion of pulverized coal and the second-stage combustion of hydrogen, and needs to simultaneously meet the air required for the first-stage combustion of pulverized coal and the second-stage burnout of hydrogen. Since the combustion speed of hydrogen is very fast, the high-temperature stable combustion conditions generated by hydrogen combustion are likely to cause a large amount of local nitrogen oxides to be generated. In order to suppress the possible generation of nitrogen oxides, compared with conventional coal-fired boilers, the present invention further reduces the chemical equivalent corresponding to the first-stage combustion of pulverized coal at the pulverized coal combustion unit 2. With the help of the high-temperature conditions formed by hydrogen combustion, the stable combustion of pulverized coal is ensured, and the adverse effects of reducing the chemical equivalent leading to the stable combustion of pulverized coal are offset. Through theoretical analysis and combustion simulation, the optimal chemical equivalent after mixing with hydrogen is 0.5-0.65, and the specific value is related to the hydrogen mixing ratio and coal combustion characteristics. That is, the amount of air configured for the pulverized coal combustion unit 2 is: the amount of air required for the second-stage combustion of hydrogen + the pulverized coal combustion equivalent of 0.5-0.65. Hydrogen is highly active and will first obtain the oxygen in the air to complete the combustion, and the pulverized coal will only partially burn. Since hydrogen has been premixed and burned in the first stage, part of the hydrogen has been burned, and the other part is not enough to form a "wind grab" with the coal powder and affect the initial combustion. According to the different proportions of hydrogen blending, the proportion of hydrogen premixing in the first stage can be adjusted to achieve the coupling of the hydrogen combustion zone and the coal powder combustion unit 2 to form a reduction zone that inhibits the generation of nitrogen oxides, and it will not cause hydrogen and coal powder to "steal wind" and cause poor ignition of coal powder. The unburned coal powder obtains an air supply greater than the chemical equivalent 1 in the burnout zone, and finally implements complete combustion. Since hydrogen and coal powder are burned in stages due to the successive supply of air, the high temperature of combustion and the chemical equivalent that is easy to generate nitrogen oxides are suppressed. In addition, except for the burnout zone, the rest of the furnace area forms a reduction zone due to lack of oxygen, which has a reducing and decomposing effect on the nitrogen oxides that have been generated. By supplying air in stages, especially hydrogen in stages, the amount of nitrogen oxides generated in the flue gas after combustion can be controlled.

[0035] Furthermore, hydrogen and pulverized coal are subjected to the third stage of combustion operation at one side of the main combustion area 11 close to the burnout zone unit 6. Hydrogen and pulverized coal are in the condition of insufficient oxygen in most of the combustion stages in the main combustion area 11, and the chemical equivalent required for theoretical combustion is not obtained until the burnout zone. Most of the combustion process is in a reducing atmosphere due to the lack of oxygen, which suppresses the high temperature of combustion and avoids the equivalent required for the generation of nitrogen oxides, so as to control the final nitrogen oxide emissions.

[0036] In summary, the embodiment of the present invention provides a coal-fueled and hydrogen mixed combustion boiler system and a coal-fueled boiler combustion method for mixing hydrogen. Compared with the prior art, the beneficial effects are as follows: 1) a pulverized coal combustion unit 2, the pulverized coal combustion unit 2 includes a first combustion assembly 21, one end of which is connected to the main combustion area 11, ensuring that the heat generated by the first combustion assembly 21 can be directly transferred to the boiler body 1, and the two ends of the first combustion assembly 21 are respectively connected to the first air duct assembly 4 and the second air duct assembly 5. The two air duct assemblies are used to provide air to the first combustion assembly 21 twice or adjust the airflow in the combustion assembly to optimize the combustion process; 2) Hydrogen combustion unit 3, the hydrogen combustion unit 3 is located below the pulverized coal combustion unit 2, this design helps to avoid the two combustion units from having different wind speeds and interfering with each other's flow fields, the hydrogen combustion unit 3 includes a hydrogen pipeline 31, a mixing chamber 32 and a second combustion assembly 33, the hydrogen pipeline 31 is responsible for providing hydrogen to the mixing chamber 32, the mixing chamber 32 is used to mix the hydrogen with the air injected by the second air duct assembly 5, one end of the second combustion assembly 33 is connected to the main combustion area 11, and the other end is connected to the mixing chamber 32, ensuring that the evenly mixed hydrogen-air mixture can be efficiently burned in the main combustion area 11, and after the combustion of hydrogen and its combustion products enter the main combustion area, a dual-fuel coupling area is formed, which can satisfy the hydrogen combustion while still maintaining the inhibitory effect on the generation of nitrogen oxides. The present invention effectively solves the problem in the prior art that when a large amount of hydrogen is mixed into a coal-fired boiler, it is easy to cause local overheating of the boiler, causing excessive nitrogen oxides and overheating of the heating surface in the furnace.

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A coal-hydrogen mixed combustion boiler system, characterized in that: It includes a boiler body, a pulverized coal combustion unit, a hydrogen combustion unit, a first air duct assembly and a second air duct assembly; The boiler body is provided with a main combustion area inside, and smoke flows from bottom to top in the main combustion area; The pulverized coal combustion unit comprises a first combustion assembly, one end of which is connected to the main combustion area, and two ends of which are respectively connected to the first air duct assembly and the second air duct assembly; The hydrogen combustion unit is arranged below the pulverized coal combustion unit, and includes a hydrogen pipeline, a mixer and a second combustion assembly. One end of the second combustion assembly is connected to the main combustion area, and the other end is connected to the mixer. Both ends of the mixer are respectively connected to the hydrogen pipeline and the second air duct assembly.

2. The coal-hydrogen mixed combustion boiler system according to claim 1 is characterized in that: The pulverized coal combustion unit also includes a first nozzle, and the number of the first nozzle and the first combustion assembly is multiple, one end of each of the first nozzles is connected to the main combustion area, and the other end of each of the first nozzles is connected to the first combustion assembly.

3. The coal-hydrogen mixed combustion boiler system according to claim 2 is characterized in that: The second air duct assembly includes a main pipe, a first branch pipe and a secondary air box. One end of the first branch pipe is connected to the main pipe, and the other end is connected to the first combustion assembly. The number of the secondary air boxes is the same as the number of the first combustion assemblies. One end of each of the secondary air boxes is connected to the first combustion assembly, and the other end is connected to the first branch pipe.

4. The coal-hydrogen mixed combustion boiler system according to claim 1, characterized in that: It also includes a burnout zone unit, which is arranged above the pulverized coal combustion unit. One end of the burnout zone unit is connected to the main combustion area, and the other end is connected to the second air duct assembly.

5. The coal-hydrogen mixed combustion boiler system according to claim 4 is characterized in that: The burnout zone unit includes a plurality of second nozzles, and the second air duct assembly also includes a second branch pipe, one end of the second branch pipe is connected to the second branch pipe, and the other end of the second branch pipe is respectively connected to the plurality of second nozzles, and the second branch pipe injects air into the main combustion zone through the second nozzle.

6. The coal-hydrogen mixed combustion boiler system according to claim 5, characterized in that: The second air duct assembly also includes a third branch pipe, which is arranged below the main pipe, one end of the third branch pipe is connected to the main pipe, and the other end of the third branch pipe is connected to the mixing chamber for injecting air into the mixing chamber.

7. A method for burning coal-fired boilers mixed with hydrogen, characterized in that: A coal-hydrogen mixed combustion boiler system as claimed in any one of claims 1 to 6, comprising: Inject air into the pulverized coal combustion unit through the first air duct assembly, mix air with the pulverized coal in the pulverized coal combustion unit, and then inject it into the first combustion assembly; Air is injected into the pulverized coal combustion unit and the hydrogen combustion unit simultaneously through the second air duct assembly, and the air injected into the hydrogen burner is mixed with hydrogen and then passed into the second combustion assembly.

8. The method for burning coal-fired boilers mixed with hydrogen according to claim 7, characterized in that: The hydrogen combustion unit is located below the pulverized coal combustion unit, and the hydrogen combustion unit and the pulverized coal combustion unit are far away from each other.

9. The method for burning coal-fired boilers mixed with hydrogen according to claim 8, characterized in that: The hydrogen in the hydrogen combustion unit is mixed with air in the mixing chamber, and the first stage combustion of hydrogen is carried out on the side of the main combustion area close to the hydrogen combustion unit, and the unburned hydrogen continues to be mixed with coal powder on the side of the main combustion area close to the coal powder combustion unit for the second stage combustion.

10. The combustion method according to claim 9, characterized in that: The hydrogen and pulverized coal are subjected to a third stage of combustion operation at one side of the main combustion area close to the burnout zone unit.

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