A circulating fluidized bed boiler for ammonia coal co-combustion and ammonia ignition and a method of using the same

Abstract

The present application relates to the technical field of boiler, disclose a kind of ammonia coal mixed combustion and ammonia ignition's circulating fluidized bed boiler and its use method, the boiler includes hearth, secondary air system, primary air system, coal supply system, ammonia system, cyclone separation system, tail heating surface, primary air system, hearth, cyclone separation system, tail heating surface are sequentially communicated, coal supply system, hearth are sequentially communicated, secondary air system, hearth are communicated, ammonia system, hearth are communicated.The present application solves the problem that the prior art exists simultaneously to achieve ammonia / coal coupling stable and efficient combustion to reach low NO x emission.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, specifically to a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, and its usage method. Background Technology

[0002] Due to the inherent combustion characteristics of coal, it is of great significance to incorporate zero-carbon fuels into coal-fired boilers.

[0003] Green ammonia has a higher volumetric energy density, milder liquefaction conditions, and is easier to store and transport. Ammonia can store hydrogen produced from new energy sources in a more cost-effective way, making it a good alternative to coal as a zero-carbon fuel and reducing carbon emissions.

[0004] Circulating fluidized bed (CFB) boilers, with their low-temperature circulating combustion and staged air supply, offer significant economic value for the efficient and low-NOx utilization of low-rank coal, and are widely used as a clean combustion technology. However, compared to conventional coal, ammonia fuel has a lower calorific value, making ignition and stable combustion relatively difficult. Therefore, achieving stable combustion of ammonia fuel is a crucial issue to address in order to fully realize its coal-for-fuel substitution effect. Furthermore, due to the significant differences in combustion characteristics between coal and ammonia, excessively high ammonia fuel blending in CFB boilers can lead to decreased combustion efficiency and a significant increase in NOx in flue gas. Achieving efficient and low-NOx combustion through coal-ammonia coupling is also worthy of consideration and research. Currently, CFB ignition primarily uses oil or natural gas, and the large amount of CO2 generated in the initial ignition phase is detrimental to emission reduction, which also requires comprehensive consideration. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, and its usage method, solving the problem that existing technologies struggle to achieve stable and efficient combustion of ammonia / coal while simultaneously achieving low NO₂ levels. x The issue of emissions.

[0006] The technical solution adopted by the present invention to solve the above problems is:

[0007] A circulating fluidized bed boiler for ammonia-coal co-firing and ammonia ignition includes a furnace, a secondary air system, a primary air system, a coal feeding system, an ammonia system, a cyclone separator system, and a tail heating surface. The primary air system, furnace, cyclone separator system, and tail heating surface are connected in sequence. The coal feeding system and furnace are connected in sequence. The secondary air system and furnace are connected. The ammonia system and furnace are connected.

[0008] As a preferred technical solution, it also includes a dust collector, an induced draft fan, and a chimney, with the tail heating surface, dust collector, induced draft fan, and chimney connected in sequence.

[0009] As a preferred technical solution, it also includes a material return system, an air distribution plate, an induced draft fan, a material return system, an ammonia system, and a furnace connected in sequence; an induced draft fan, a material return system, and a furnace connected in sequence; a primary air system, an air distribution plate, and a furnace connected in sequence; and a primary air system and an ammonia system connected in sequence.

[0010] As a preferred technical solution, the ammonia system includes an ammonia tank, a shut-off valve, an ignition ammonia pipeline, and an ammonia co-firing pipeline. The ammonia tank, shut-off valve, ammonia co-firing pipeline, and return system are connected in sequence, and the ammonia tank, shut-off valve, ignition ammonia pipeline, and primary air system are connected in sequence.

[0011] As a preferred technical solution, the secondary air system includes a secondary air fan, a secondary air preheater, secondary air ducts on the front wall, secondary air ducts on the rear wall, secondary air ducts below the front wall, and secondary air ducts below the rear wall. The secondary air fan and the secondary air preheater are connected. One end of each of the secondary air ducts on the front wall, the rear wall, the front wall, and the rear wall is connected to the secondary air preheater. The other end of each of the secondary air ducts on the front wall, the rear wall, the front wall, and the rear wall is connected to the furnace.

[0012] As a preferred technical solution, the primary air system includes a primary air fan, a primary air preheater, an ignition burner, and a coal feeding air duct. The primary air fan, primary air preheater, primary air duct, ignition burner, and air distribution plate are connected in sequence. The primary air preheater, coal feeding air duct, and furnace are connected in sequence. The primary air duct includes a parallel ignition air duct and a fluidizing air duct. An ignition air control device is installed on the ignition air duct, and a fluidizing air control device is installed on the fluidizing air duct. The coal feeding air duct includes a parallel coal feeding air duct I, a coal feeding air duct II, and a coal feeding air duct III.

[0013] As a preferred technical solution, the material return system includes a U-valve fan, a U-valve, a material return pipe, a recirculated flue gas duct, an induced draft fan, a recirculated flue gas duct, a U-valve fan, a U-valve, and a furnace connected in sequence.

[0014] As a preferred technical solution, the cyclone separation system includes a cyclone separator inlet pipe, a cyclone separator, a cyclone separator outlet pipe, and a furnace, a cyclone separator inlet pipe, a cyclone separator, a cyclone separator outlet pipe, and a tail heating surface connected in sequence.

[0015] A method for using a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, wherein the co-firing of ammonia fuel is controlled by opening, closing or adjusting the opening degree of the ammonia co-firing pipeline.

[0016] The method of using a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition involves controlling the opening of the ammonia ignition pipeline to ignite the ammonia fuel, and controlling the opening, closing or degree of opening of the ammonia pipeline to achieve staged co-firing of the ammonia fuel.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] This invention proposes a circulating fluidized bed (CFB) boiler with ammonia-coal co-firing and ammonia ignition. It fully leverages the clean combustion advantages of CFB boilers by employing a zoned combustion method. Through multi-stage coal feeding, multi-stage air distribution, and multi-stage ammonia injection, it achieves rated power coal combustion, a high proportion of ammonia fuel for carbon reduction, and zero-CO2 emission boiler ignition. This results in better stable combustion and higher combustion efficiency, promotes complete fuel combustion and early nitrogen oxide control, significantly increases boiler fuel flexibility, and ultimately achieves carbon emission reduction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition as described in this invention.

[0020] Figure 2 for Figure 1 One of the magnified views of a section;

[0021] Figure 3 for Figure 1 The second enlarged view of a part.

[0022] The labels and their corresponding names in the attached diagram:

[0023] 1. Furnace chamber; 11. Primary combustion zone; 12. Secondary combustion zone; 13. Tertiary combustion zone; 14. Quaternary combustion zone;

[0024] 2. Secondary air system; 21. Secondary air fan; 22. Secondary air preheater; 23. Secondary air duct on the front wall; 24. Secondary air duct on the rear wall; 25. Secondary air duct under the front wall; 26. Secondary air duct under the rear wall.

[0025] 3. Primary air system; 31. Primary air fan; 32. Primary air preheater; 33. Ignition air control device; 34. Ignition air duct; 35. Fluidizing air control device; 36. Fluidizing air duct; 37. Ignition burner; 38. Coal spreading air duct; 381. Coal spreading air I duct; 382. Coal spreading air II duct; 383. Coal spreading air III duct;

[0026] 4. Coal feeding system;

[0027] 5. Ammonia system, 51. Ammonia tank, 52. Shut-off valve, 53. Ignition ammonia pipeline, 531. Flow meter I, 532. Regulating valve I, 533. Quick-closing valve I, 54. Ammonia blending pipeline, 541. Flow meter II, 542. Regulating valve II, 543. Quick-closing valve II;

[0028] 6. Material return system; 61. U-valve fan; 62. U-valve; 63. Material return pipe; 64. Recirculated flue gas duct.

[0029] 7. Air distribution panel;

[0030] 8. Cyclone separation system; 81. Cyclone separator inlet pipe; 82. Cyclone separator; 83. Cyclone separator outlet pipe;

[0031] 9. Heating surface at the tail end;

[0032] 10. Dust collector;

[0033] 101. Exhaust fan;

[0034] 102. Chimney. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0036] Example 1

[0037] like Figures 1 to 3 As shown, the purpose of this invention is to comprehensively solve the technical problems existing in the above background, and to propose a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, so as to achieve stable and efficient ammonia / coal coupled combustion while achieving low NO. x emission.

[0038] The ammonia-coal co-firing and ammonia-ignition circulating fluidized bed (CFB) boiler proposed in this invention fully leverages the clean combustion advantages of CFB boilers. Employing a zoned combustion method, it achieves rated power coal combustion, high-proportion ammonia-fuel co-firing for carbon reduction, and zero-CO2 emission boiler ignition through multi-stage coal feeding, multi-stage air distribution, and multi-stage ammonia injection. This results in better stable combustion, higher combustion efficiency, and facilitates complete fuel combustion and early nitrogen oxide control, significantly increasing boiler fuel flexibility and ultimately achieving carbon emission reduction.

[0039] To achieve the above objectives, the present invention adopts the following technical solution:

[0040] As shown in the figure, the present invention proposes a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, including a furnace 1, a secondary air system 2, a primary air system 3, a coal feeding system 4, an ammonia system 5, a material return system 6, an air distribution plate 7, a cyclone separation system 8, a tail heating surface 9, a dust collector 10, an induced draft fan 101, and a chimney 102.

[0041] The secondary air system 2 includes a secondary air fan 21, a secondary air preheater 22, a secondary air duct 23 on the front wall, a secondary air duct 24 on the rear wall, a secondary air duct 25 below the front wall, and a secondary air duct 26 below the rear wall. Each stage of the secondary air nozzle is connected to the furnace 1 to achieve staged air delivery into the furnace.

[0042] The primary air system 3 includes a primary air fan 31, a primary air preheater 32, an ignition air control device 33, an ignition air duct 34, a fluidizing air control device 35, a fluidizing air duct 36, an ignition burner 37, and a coal feeding air duct 38. The coal feeding air duct 38 further includes a coal feeding air I duct 381, a coal feeding air II duct 382, ​​and a coal feeding air III duct 383. Primary air is supplied to the furnace 1 in stages through the air distribution plate 7 and the coal feeding air duct 38.

[0043] The ammonia system 5 includes an ammonia tank 51, a shut-off valve 52, an ammonia ignition pipeline 53, and an ammonia blending pipeline 54. The ammonia ignition pipeline 53 and the ammonia blending pipeline 54 each include flow meters (flow meter I 531 and flow meter II 541), regulating valves, quick-closing valves, and other control equipment to achieve the delivery and precise control of ammonia.

[0044] The material return system 6 includes a U-valve fan 61, a U-valve 62, a material return pipe 63, and a recirculated flue gas duct 64. The material return pipe 63 is connected to the furnace 1, and the recirculated flue gas duct 64 is introduced from the dust collector 10 and the induced draft fan 101. Under the action of the U-valve fan 61, the flue gas is drawn back to the furnace 1.

[0045] The cyclone separation system 8 includes a cyclone separator inlet pipe 81, a cyclone separator 82, and a cyclone separator outlet pipe 83. Through cyclone separation, unqualified combustion solid products are recycled and burned again in the furnace, while the flue gas enters the tail heating surface 9 for heat exchange.

[0046] The ammonia co-firing pipeline 54 is connected to the return pipe 63. After entering the return pipe 63, the ammonia gas mixes with the recirculated flue gas pipeline 64. The temperature in this area is about 800℃, which is conducive to the decomposition of ammonia. The unburned binary and ternary components after decomposition enter the secondary combustion zone 12 in the furnace 1 for combustion. When the boiler co-firing ammonia fuel, the quick-closing valve 543Ⅱ and the regulating valve 542Ⅱ on the ammonia co-firing pipeline 54 are opened to achieve efficient and low-NOx co-firing of ammonia fuel.

[0047] The ammonia ignition pipeline 53 is connected to the ignition burner 37, which is connected to the furnace 1. When the boiler is ignited, the quick-closing valve 533Ⅰ and the regulating valve 532Ⅰ on the ammonia ignition pipeline 53 are opened to ignite the ammonia fuel. At the same time, when the boiler is co-firing ammonia fuel, the quick-closing valve 533Ⅰ and the regulating valve 532Ⅰ on the ammonia ignition pipeline 53 can also be opened to achieve staged co-firing of ammonia fuel in the primary combustion zone 11.

[0048] The furnace is fed in the following order from bottom to top: fluidizing air through fluidizing air duct 36, coal feeding air through coal feeding air duct 38, recirculated flue gas and ammonia fuel through return material pipe 63, primary secondary air through secondary air duct 25 under the front wall and secondary air duct 26 under the rear wall, and secondary secondary air through secondary air duct 23 on the front wall and secondary air duct 24 on the rear wall. This forms a primary combustion zone 11, a secondary combustion zone 12, a tertiary combustion zone 13, and a quaternary combustion zone 14 within the furnace. Through multi-dimensional air and fuel supply, multi-dimensional and multi-zone combustion is achieved, resulting in high-efficiency and low-NOx combustion.

[0049] The coal feeding system 4 is connected to the coal spreading air pipeline I 381, coal spreading air pipeline II 382, ​​and coal spreading air pipeline III 383 to supply fuel coal. The multi-stage coal spreading air pipeline 38 can prevent problems such as poor coal feeding and coking at the coal feed inlet.

[0050] The air distribution plate 7 can fluidize the bed material, the fuel coal fed through the coal feeding system 4, and the unqualified combustion solid products returned to the furnace through the return pipe 63, so as to achieve uniform, efficient and low-NOx combustion of fuel in the furnace.

[0051] The tail heating surface 9 can be equipped with heat exchange equipment such as superheaters, reheaters, and economizers to achieve comprehensive utilization of flue gas heat.

[0052] The primary air preheater 32 and the secondary air preheater 22 introduce high-temperature flue gas from the tail heating surface 9 to exchange heat with the air, thereby increasing the air temperature and improving boiler efficiency.

[0053] The dust collector 10 filters the dust generated after combustion in the furnace, achieving clean emission of flue gas.

[0054] The induced draft fan 101 controls the balance of flue gas resistance in the entire boiler. Through the proper control of the induced draft fan 101, normal combustion in the entire furnace is maintained and the flue gas can be smoothly discharged into the atmosphere through the chimney 102.

[0055] This invention discloses an ammonia-coal co-firing and ammonia-ignition circulating fluidized bed boiler, which mainly includes a furnace, a secondary air system, a primary air system, a coal feeding system, an ammonia system, a material return system, an air distribution plate, a cyclone separation system, a tail heating surface, a dust collector, an induced draft fan, and a chimney.

[0056] Preferably, the furnace is fed from bottom to top with fluidizing air, primary air, coal feeding air, return material conveying flue gas, secondary air, ammonia fuel input by the ignition burner, coal fuel input by the coal feeding air, and unburned particles and ammonia fuel input by the return material, forming a primary combustion zone, a secondary combustion zone, a tertiary combustion zone, and a quaternary combustion zone. Through multi-dimensional air and fuel supply, multi-dimensional and multi-zone combustion is formed to achieve the purpose of high-efficiency and low-NOx combustion.

[0057] Preferably, ammonia fuel is fed from the return system and the ignition burner. The total amount of ammonia entering the return pipe is preferably designed to be 35-45% of the heat input, and the number of ammonia fuel blending pipelines entering the return pipe is less than or equal to the number of return pipes. The total amount of ammonia entering the ignition burner is preferably designed to be 5-15% of the heat input, so as to realize the ignition and blending of ammonia fuel. The ammonia fuel conveying pipeline is equipped with regulating devices, cutting-off devices, etc., so as to precisely control the amount of ammonia blending.

[0058] Preferably, the return material system uses flue gas for return material conveying. The flue gas can be drawn from the tail heating surface area at high temperature or from the dust collector after the dust collector.

[0059] Example 2

[0060] like Figures 1 to 3 As shown, as a further optimization of Embodiment 1, this embodiment also includes the following technical features based on Embodiment 1:

[0061] The present invention will now be described in further detail with reference to the accompanying drawings.

[0062] Case 1: Implementing a 0-50% ammonia blending scheme in a 300MW-class CFB boiler

[0063] A certain 300MW class CFB boiler includes a furnace 1, a secondary air system 2, a primary air system 3, a coal feeding system 4, an ammonia system 5, a return material system 6, an air distribution plate 7, a cyclone separation system 8, a tail heating surface 9, a dust collector 10, an induced draft fan 101, and a chimney 102.

[0064] The secondary air system 2 includes a secondary air fan 21, a secondary air preheater 22, a secondary air duct 23 on the front wall, a secondary air duct 24 on the rear wall, a secondary air duct 25 below the front wall, and a secondary air duct 26 below the rear wall. The upper and lower secondary air are arranged in stages along the height of the furnace 1. The secondary air ducts 23 on the front wall, 24 on the rear wall, 25 below the front wall, and 26 below the rear wall are each equipped with 12 to 16 nozzles along the width of the furnace 1. Each secondary air nozzle is connected to the furnace 1 to achieve staged air delivery of secondary air into the furnace.

[0065] The primary air system 3 includes a primary air fan 31, a primary air preheater 32, an ignition air control device 33, an ignition air duct 34, a fluidizing air control device 35, a fluidizing air duct 36, an ignition burner 37, and a coal feeding air duct 38. The coal feeding air duct 38 further includes coal feeding air I duct 381, coal feeding air II duct 382, ​​and coal feeding air III duct 383. Primary air is supplied to the furnace 1 in stages through the air distribution plate 7 and the coal feeding air duct 38. 8 to 14 sets of coal feeding systems 4 are arranged along the width of the furnace 1, and 2 to 5 coal feeding air paths are set on the coal feeding systems 4 to achieve the supply of coal fuel.

[0066] Each furnace is equipped with 4 to 6 sets of ignition burners 37. The number of ignition ammonia pipes 53 is the same as the number of ignition burners 37.

[0067] The ammonia system 5 includes an ammonia tank 51, a shut-off valve 52, an ignition ammonia pipeline 53, and an ammonia blending pipeline 54. The ignition ammonia pipeline 53 and the ammonia blending pipeline 54 each include flow meters, regulating valves, and quick-closing valves to achieve ammonia delivery and precise control. The return system 6 includes a U-valve fan 61, a U-valve 62, a return pipe 63, and a recirculation flue gas pipeline 64. The return pipe 63 is connected to the furnace 1, and the recirculation flue gas pipeline 64 is introduced from behind the dust collector 10 and before the induced draft fan 101, and the flue gas is returned to the furnace 1 under the action of the U-valve fan 61. The ammonia system 5 is designed for 50% boiler heat load input, with the total amount of ammonia entering the return pipe designed for 35-45% heat input and the total amount of ammonia entering the ignition burner designed for 5-15% heat input.

[0068] The cyclone separation system 8 includes a cyclone separator inlet pipe 81, a cyclone separator 82, and a cyclone separator outlet pipe 83. Through cyclone separation, substandard combustion solid products are recycled and burned again in the furnace, while the flue gas enters the tail heating surface 9 for heat exchange. The cyclone separation system 8 is connected to the furnace 1, the return material system 6, and the tail heating surface 9. Each furnace is equipped with 2 to 4 sets of cyclone separation systems 8.

[0069] The ammonia co-firing pipeline 54 is connected to the return feed pipe 63. After entering the return feed pipe 63, the ammonia gas mixes with the recirculated flue gas pipeline 64. The temperature in this area is about 800℃, which is conducive to the decomposition of ammonia. The unburned binary and ternary components after decomposition enter the secondary combustion zone 12 in the furnace for combustion. When the boiler co-firing ammonia fuel, the quick-closing valve II 543 and the regulating valve II 542 on the ammonia co-firing pipeline 54 are opened to achieve efficient and low-NOx co-firing of ammonia fuel. Each boiler is equipped with 2 to 4 sets of return feed pipes 63, and the number of ammonia co-firing pipelines 54 and return feed pipes 63 is the same.

[0070] The ammonia ignition pipeline 53 is connected to the ignition burner 37, which is connected to the furnace 1. When the boiler is ignited, the quick-closing valve I533 and the regulating valve I532 on the ammonia ignition pipeline 53 are opened to ignite the ammonia fuel. At the same time, after the boiler is running normally, the quick-closing valve I533 and the regulating valve I532 on the ammonia ignition pipeline 53 can be opened to achieve staged co-firing of ammonia fuel in the primary combustion zone 11.

[0071] The furnace is fed in the following order from bottom to top: fluidizing air through fluidizing air duct 36, coal feeding air through coal feeding air duct 38, recirculated flue gas and ammonia fuel through return material pipe 63, primary secondary air through secondary air duct 25 under the front wall and secondary air duct 26 under the rear wall, and secondary secondary air through secondary air duct 23 on the front wall and secondary air duct 24 on the rear wall. This forms a primary combustion zone 11, a secondary combustion zone 12, a tertiary combustion zone 13, and a quaternary combustion zone 14 within the furnace. Through multi-dimensional air and fuel supply, multi-dimensional and multi-zone combustion is achieved, resulting in high-efficiency and low-NOx combustion.

[0072] The coal feeding system 4 is connected to the coal spreading air pipeline I 381, coal spreading air pipeline II 382, ​​and coal spreading air pipeline III 383 to supply fuel coal. The multi-stage coal spreading air can prevent problems such as poor coal feeding and coking at the coal feed inlet.

[0073] The air distribution plate 7 can fluidize the bed material, the fuel coal fed through the coal feeding system 4, and the unqualified combustion solid products returned to the furnace through the return pipe 63, so as to achieve uniform, efficient and low-NOx combustion of fuel in the furnace.

[0074] The tail heating surface 9 can be equipped with heat exchange equipment such as superheaters, reheaters, and economizers to achieve comprehensive utilization of flue gas heat.

[0075] The primary air preheater 32 and the secondary air preheater 22 introduce high-temperature flue gas from the tail heating surface 9 to exchange heat with the air, thereby increasing the air temperature and improving boiler efficiency.

[0076] The dust collector 10 filters the dust generated after combustion in the furnace, achieving clean emission of flue gas.

[0077] The induced draft fan 101 controls the balance of flue gas resistance in the entire boiler. Through the proper control of the induced draft fan 101, normal combustion in the entire furnace is maintained and the flue gas can be smoothly discharged into the atmosphere through the chimney 102.

[0078] Case 2: Implementing a 0-50% ammonia blending scheme in a 300MW-class CFB boiler

[0079] The main difference between Case 2 and Case 1 is that the recirculated flue gas duct 64 is introduced from the heating surface 9 section before and after the dust collector 10. The temperature in this section is higher than that introduced after the dust collector 10, which can promote the decomposition of ammonia.

[0080] Case 3: Implementing a 0-50% ammonia blending scheme for a 660MW-class CFB boiler

[0081] The main differences between Case 3 and Case 1 are as follows: the number of nozzles along the width of furnace 1 for the secondary air ducts 23 on the front wall, 24 on the rear wall, 25 below the front wall, and 26 below the rear wall is different; the number of ignition burners 37 and ignition ammonia pipes 53 is different; the number of cyclone separation systems 8 is different; the number of ammonia co-firing pipes 54 and return pipes 63 is different; and the number of coal feeding systems 4 is different.

[0082] The same principles apply to the co-firing and ignition of ammonia fuel in boilers of other capacity levels, and will not be listed here.

[0083] As described above, the present invention can be implemented well.

[0084] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Based on the technical essence of the present invention, any simple modifications, equivalent substitutions, and improvements made to the above embodiments within the spirit and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition, characterized in that, It includes a furnace (1), a secondary air system (2), a primary air system (3), a coal feeding system (4), an ammonia system (5), a cyclone separator system (8), and a tail heating surface (9). The primary air system (3), the furnace (1), the cyclone separator system (8), and the tail heating surface (9) are connected in sequence. The coal feeding system (4) and the furnace (1) are connected in sequence. The secondary air system (2) and the furnace (1) are connected. The ammonia system (5) and the furnace (1) are connected. It also includes a material return system (6), an air distribution plate (7), an induced draft fan (101), a material return system (6), an ammonia system (5), and a furnace (1) connected in sequence. The induced draft fan (101), the material return system (6), and the furnace (1) are connected in sequence. The primary air system (3), the air distribution plate (7), and the furnace (1) are connected in sequence. The primary air system (3) and the ammonia system (5) are connected in sequence. The ammonia system (5) includes an ammonia tank (51), a shut-off valve (52), an ammonia ignition pipeline (53), and an ammonia blending pipeline (54). The ammonia tank (51), shut-off valve (52), ammonia blending pipeline (54), and return system (6) are connected in sequence. The ammonia tank (51), shut-off valve (52), ammonia ignition pipeline (53), and primary air system (3) are connected in sequence. The furnace is fed in the following order from bottom to top: fluidizing air through fluidizing air duct (36), coal spreading air through coal spreading air duct (38), recirculated flue gas and ammonia fuel through return material pipe (63), primary secondary air through secondary air duct (25) under the front wall and secondary air duct (26) under the rear wall, and secondary secondary air through secondary air duct (23) on the front wall and secondary air duct (24) on the rear wall, forming a primary combustion zone (11), a secondary combustion zone (12), a tertiary combustion zone (13), and a quaternary combustion zone (14) in the furnace. The ammonia co-firing pipeline (54) is connected to the return pipe (63) and enters the secondary combustion zone (12) of the furnace (1) for combustion.

2. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition according to claim 1, characterized in that, It also includes a dust collector (10), an induced draft fan (101), and a chimney (102), with the tail heating surface (9), dust collector (10), induced draft fan (101), and chimney (102) connected in sequence.

3. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition according to claim 1, characterized in that, The secondary air system (2) includes a secondary air fan (21), a secondary air preheater (22), a secondary air duct on the front wall (23), a secondary air duct on the rear wall (24), a secondary air duct below the front wall (25), and a secondary air duct below the rear wall (26). The secondary air fan (21) and the secondary air preheater (22) are connected. One end of the secondary air duct on the front wall (23), the secondary air duct on the rear wall (24), the secondary air duct below the front wall (25), and the secondary air duct below the rear wall (26) are respectively connected to the secondary air preheater (22). The other end of the secondary air duct on the front wall (23), the secondary air duct on the rear wall (24), the secondary air duct below the front wall (25), and the secondary air duct below the rear wall (26) are respectively connected to the furnace (1).

4. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition according to claim 1, characterized in that, The primary air system (3) includes a primary air fan (31), a primary air preheater (32), an ignition burner (37), and a coal-spreading air duct (38). The primary air fan (31), the primary air preheater (32), the primary air duct, the ignition burner (37), and the air distribution plate (7) are connected in sequence. The primary air preheater (32), the coal-spreading air duct (38), and the furnace (1) are connected in sequence. The primary air duct includes a parallel ignition air duct (34) and a fluidizing air duct (36). The ignition air duct (34) is equipped with an ignition air control device (33), and the fluidizing air duct (36) is equipped with a fluidizing air control device (35). The coal-spreading air duct (38) includes a parallel coal-spreading air I duct (381), a coal-spreading air II duct (382), and a coal-spreading air III duct (383).

5. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition according to claim 1, characterized in that, The material return system (6) includes a U-valve fan (61), a U-valve (62), a material return pipe (63), and a recirculated flue gas duct (64). The induced draft fan (101), the recirculated flue gas duct (64), the U-valve fan (61), the U-valve (62), and the furnace (1) are connected in sequence.

6. A circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition according to any one of claims 1, 3 to 5, characterized in that, The cyclone separation system (8) includes a cyclone separator inlet pipe (81), a cyclone separator (82), a cyclone separator outlet pipe (83), and the furnace (1), the cyclone separator inlet pipe (81), the cyclone separator (82), the cyclone separator outlet pipe (83), and the tail heating surface (9) are connected in sequence.

7. A method of using a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition as described in any one of claims 1, 3 to 5, characterized in that, The co-firing of ammonia fuel is controlled by opening, closing or adjusting the opening degree of the ammonia co-firing pipeline (54).

8. A method of using a circulating fluidized bed boiler with ammonia-coal co-firing and ammonia ignition as described in any one of claims 1, 3 to 5, characterized in that, The opening of the ammonia ignition pipeline (53) is controlled to achieve the ignition of ammonia fuel, and the opening, closing or opening degree of the ammonia pipeline (53) is controlled to achieve the staged co-firing of ammonia fuel.

Images