Circulating fluidized bed boiler and ammonia-doped combustion method

Abstract

The invention provides a circulating fluidized bed boiler and an ammonia-doped combustion method, and belongs to the field of fluidized bed boilers. The side surface of the upper part of a hearth in the boiler is communicated with an inlet flue of the cyclone separator; a gas inlet and an air inlet are formed in an inlet flue of the cyclone separator, a thermocouple is arranged in the cyclone separator, and a flue gas analysis device and an ammonia spraying port are arranged at an outlet of the center cylinder; the introduced fuel gas and air are combusted in the cyclone separator, so that the temperature in the cyclone separator is 950-1000 DEG C; ammonia is injected from an ammonia injection port at the tail gas outlet to reduce nitrogen oxides in the tail gas; the thermocouple monitors the temperature in the cyclone separator in real time, and the flue gas analysis device monitors the concentration of nitric oxide in the tail gas in real time; the PID controller controls the flow of fuel gas, air and sprayed ammonia in real time according to the internal temperature of the cyclone separator and the concentration of nitrogen oxide. The combustion efficiency of the boiler is guaranteed, emission of nitric oxide, especially nitrous oxide, during ammonia-doped combustion of the circulating fluidized bed is reduced, and the boiler is simple and easy to transform.

Description

Technical Field

[0001] The invention belongs to the field of circulating fluidized bed boilers, and in particular relates to a circulating fluidized bed boiler and an ammonia-blending combustion method. Background Art

[0002] As an efficient reaction device, circulating fluidized bed boiler has the advantages of wide adaptability to coal types, strong load regulation ability and low pollutant emission level. However, at present, fluidized bed boilers mainly rely on fossil fuels, but the excessive use of fossil fuels will lead to a large amount of carbon dioxide emissions, which in turn leads to the greenhouse effect. Therefore, the development of zero-carbon alternative fuels is a promising method. Among various alternative fuels, ammonia has a mature storage and transportation system and a complete industrial system, and can replace part of coal and be directly used in the current circulating fluidized bed boiler, which can play an important role in the carbon-free transformation of the energy structure. However, when ammonia is mixed in the circulating fluidized bed boiler for combustion, due to the low combustion temperature and the increase in the nitrogen content in the fuel, there will be a problem of high nitrogen oxide and nitrous oxide emissions. Among them, nitrous oxide is a greenhouse gas like carbon dioxide, and the greenhouse effect it can cause is 298 times that of carbon dioxide, which is more harmful to the environment. The above reasons greatly limit the application of ammonia in circulating fluidized beds.

[0003] In the prior art, the safe use of ammonia in circulating fluidized bed boilers is generally ensured by reducing nitrogen oxide emissions. For example, the Chinese utility model patent with publication number CN204554797U discloses a circulating fluidized bed combustion device that reduces nitrogen oxide emissions, and isolates the reduction zone from the burnout zone through a gas-solid separator, thereby reducing nitrogen oxide emissions. The Chinese invention patent with publication number CN116105130A discloses a circulating fluidized bed boiler system and method for achieving pure ammonia combustion, which achieves pure ammonia combustion by filling a large amount of solid bed material particles with excellent heat transfer performance and large thermal inertia into the furnace. However, the above method cannot reduce the emission of nitrous oxide components, and still puts great pressure on the environment, resulting in ammonia being unable to be widely used in circulating fluidized bed boilers. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present invention aims to provide a circulating fluidized bed boiler and an ammonia-blended combustion method to reduce the emissions of nitrogen oxides and nitrous oxide during ammonia-blended combustion in a fluidized bed boiler.

[0005] In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solution:

[0006] In a first aspect, an embodiment of the present invention provides a circulating fluidized bed boiler, the circulating fluidized bed boiler comprising: a wind chamber 1, a furnace 2, a cyclone separator inlet flue 3, a cyclone separator 4, a thermocouple 51, a first PID controller 52, and a material return device 6;

[0007] The wind chamber 1 is arranged at the bottom of the furnace 2, and the upper side of the furnace 2 is connected to the cyclone separator inlet flue 3. A thermocouple 51 is arranged inside the cyclone separator 4, and the thermocouple 51 is connected to the first PID controller 52; a return device 6 is arranged at the lower end of the cyclone separator 4;

[0008] Among them, the near-cyclone separator end of the cyclone separator inlet flue 3 is respectively provided with at least one gas inlet 31 and a gas flow control valve 32, at least one air inlet 33 and an air flow control valve 34; and the gas inlet 31 and the air inlet 32 ​​are both connected to the cyclone separator inlet flue 3; the gas flow control valve 32 and the air flow control valve 34 are simultaneously connected to the first PID controller 51.

[0009] As a preferred embodiment of the present invention, the gas inlet 31 and the air inlet 33 on the cyclone separator inlet flue 3 are arranged opposite to each other up and down.

[0010] As a preferred embodiment of the present invention, the gas inlet 31 and the air inlet 33 on the cyclone separator inlet flue 3 are alternately arranged on the same side.

[0011] As a preferred embodiment of the present invention, the number of the gas inlets 31 and the number of the air inlets 33 are the same.

[0012] As a preferred embodiment of the present invention, the fuel gas is one or more of ammonia, hydrogen, and natural gas.

[0013] As a preferred embodiment of the present invention, the boiler further includes a first flue gas analysis device 71, a second flue gas analysis device 72 and a second PID controller 73;

[0014] The first flue gas analysis device 71 and the second flue gas analysis device 72 are respectively arranged on the outlet side wall of the cyclone separator central tube 41 of the cyclone separator 4, and the second PID controller 73 is connected to the first flue gas analysis device 71 and the second flue gas analysis device 72 at the same time;

[0015] On the side wall where the outlet of the cyclone separator center tube 41 is arranged, at least one ammonia injection port 42 and a flow control valve 43 are arranged between the first flue gas analysis device 71 and the second flue gas analysis device 72; the second PID controller 73 is also connected to the flow control valve 43.

[0016] As a preferred embodiment of the present invention, a primary air inlet 11 is provided on the lower bottom surface of the wind chamber 1, and an ammonia inlet 12 is provided on the side of the wind chamber 1; at least one secondary air inlet 21 is provided on the side wall of the furnace 2, and the position of the secondary air inlet 21 is slightly higher than the bed height of the bed material in the furnace 2.

[0017] As a preferred embodiment of the present invention, one or more second ammonia inlets 22 and second air inlets 23 are further provided on the side wall of the furnace 2 to adjust the combustion state in the furnace 2; the second ammonia inlet 22 and the second air inlet 23 are higher than the secondary air inlet 21.

[0018] In a second aspect, an embodiment of the present invention further provides an ammonia-blended combustion method for a circulating fluidized bed boiler, the method being implemented based on the circulating fluidized bed boiler provided above, comprising:

[0019] Step S1, ammonia and primary air are mixed evenly in a wind chamber arranged at the lower part of the furnace, and then sent into the furnace for combustion; the air volume of the primary air and the secondary air is adjusted to maintain a reducing atmosphere at the lower part of the furnace;

[0020] Step S2, the high-temperature flue gas generated after the combustion in the furnace enters the inlet flue of the cyclone separator; at the same time, the gas and air introduced through the gas inlet and the air inlet are mixed; the high-temperature flue gas ignites the mixture of gas and air and mixes with it, and then enters the cyclone separator together;

[0021] Step S3, the mixed gas burns inside the cyclone separator, and the thermocouple monitors the temperature inside the cyclone separator in real time and uploads the temperature to the first PID controller. At this time, the first PID controller adjusts the opening of the gas flow control valve and the air flow control valve to accurately adjust the flow of gas and air introduced, so that the temperature inside the cyclone separator is maintained at 950-1000°C; at this temperature, nitrous oxide in the high-temperature flue gas is decomposed into nitrogen and oxygen;

[0022] Step S4, under the action of the cyclone separator, the solid particles in the high-temperature flue gas are separated and returned to the furnace through the return device;

[0023] Step S5, the tail gas separated by the cyclone separator is discharged through the central tube of the cyclone separator.

[0024] As a preferred embodiment of the present invention, step S5 includes:

[0025] Step S51, in the front half of the central cylinder of the cyclone separator, the first flue gas analysis device analyzes the concentration of nitrogen oxides in the tail gas, and uploads the detected concentration of nitrogen oxides to the second PID controller, and the second PID controller adjusts the opening of the flow control valve according to the concentration of nitrogen oxides, so that the ammonia injected from the ammonia injection port fully reacts with the nitrogen oxides in the tail gas, and the nitrogen oxides are reduced to generate new tail gas, which enters the rear half of the central cylinder of the cyclone separator;

[0026] Step S52, in the second half of the cyclone separation center tube, the second flue gas analysis device analyzes the nitrogen oxide concentration in the exhaust gas again; if the detected nitrogen oxide concentration meets the emission standard, the exhaust gas is directly discharged; if the detected nitrogen oxide concentration does not meet the emission standard, the detected nitrogen oxide concentration is uploaded to the second PID controller, and the second PID controller adjusts the opening of the flow control valve based on the two nitrogen oxide concentrations uploaded by the first flue gas analysis device and the second flue gas analysis device, thereby controlling the nitrogen injection flow rate until the exhaust gas detected by the second flue gas analysis device meets the emission standard.

[0027] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0028] The circulating fluidized bed boiler and ammonia-blended combustion method provided in the embodiment of the present invention ensure that the fuel entering the furnace is fully mixed with the combustion-supporting air by means of an ammonia and primary air premixing inlet arranged at the bottom of the furnace. At the same time, there is no need to carry out large-scale transformation of the existing boiler, and the operation is simple and easy to implement. Due to the advance mixing of the fuel, the stoichiometric ratio of the combustion area can be more effectively controlled, thereby forming a reducing atmosphere at the bottom of the furnace. This reducing atmosphere reduces the formation of nitrogen oxides. At the same time, the staged supply design of the fuel and air provides a sufficient oxidizing environment above the bed surface, ensuring that the fuel is completely burned and inhibiting the further accumulation of the generated nitrogen oxides. This optimized atmosphere distribution helps to reduce nitrogen oxide emissions while improving combustion efficiency.

[0029] The cyclone separator is not only used for particle separation, but also achieves fine temperature control through precise gas and air supply at its inlet; the temperature in the cyclone separator is monitored in real time by thermocouples and maintained at 950-1000°C, ensuring that nitrous oxide is decomposed into nitrogen and oxygen at high temperature, thereby reducing the emission of nitrogen oxides and nitrous oxide as a whole;

[0030] In the exhaust gas treatment process, the real-time monitoring of the flue gas analyzer installed at the outlet of the central tube can accurately detect the concentration changes of nitrogen oxides; based on the real-time monitoring data, the system can dynamically adjust the injection amount of ammonia to convert nitrogen oxides into harmless nitrogen and water; this dynamic adjustment mechanism can not only ensure that the concentration of nitrogen oxides in the exhaust gas is always lower than the environmental protection standard, but also avoid the excessive use of ammonia, thereby improving the economy and environmental benefits of the entire system;

[0031] The ammonia-blended combustion method of the circulating fluidized bed can flexibly adjust the ammonia blending ratio according to the working conditions. This flexible configuration provides a variable adaptation scheme for different fuel characteristics and boiler operating conditions. The number and position of each inlet and injection port in the system can be optimized according to the on-site working conditions to ensure effective operation under various conditions, thereby improving the overall efficiency and environmental performance of the system.

[0032] Of course, it is not necessary to achieve all of the advantages described above at the same time to implement any product or method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a schematic structural diagram of a circulating fluidized bed boiler provided in an embodiment of the present invention.

[0035] Description of reference numerals:

[0036] 1-wind chamber; 11-primary air inlet; 12-ammonia inlet; 2-furnace; 21-secondary air inlet; 22-second ammonia inlet; 23-second air inlet; 3-cyclone separator inlet flue; 31-gas inlet; 32-gas flow control valve; 33-air inlet; 34-air flow control valve; 4-cyclone separator; 41-cyclone separator center tube; 42-ammonia injection port; 43-flow control valve; 51-thermocouple; 52-first PID controller; 6-return device; 71-first flue gas analysis device; 72-second flue gas analysis device; 73-second PID controller. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. It should be noted that the embodiments of the present invention and the features in the embodiments can also be combined with each other without conflict.

[0038] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present invention, the terms "first", "second", "third", "fourth", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0039] Based on the problem of ammonia-doped combustion in a circulating fluidized bed, an embodiment of the present invention provides a circulating fluidized bed boiler and an ammonia-doped combustion method.

[0040] like Figure 1 As shown, the circulating fluidized bed boiler provided in the embodiment of the present invention comprises: a wind chamber 1, a furnace 2, a cyclone separator inlet flue 3, a cyclone separator 4, a thermocouple 51, a first PID controller 52, a return device 6, a first flue gas analysis device 71, a second flue gas analysis device 72 and a second PID controller 73; the wind chamber 1 is arranged at the bottom of the furnace 2, and the upper side of the furnace 2 is connected to the cyclone separator inlet flue 3, and a thermocouple 51 is arranged inside the cyclone separator 4, and the thermocouple 51 is connected to the first PID controller 52; a return device 6 is arranged at the lower end of the cyclone separator 4, and the return device 6 is connected to the furnace 1; the first flue gas analysis device 71 and the second flue gas analysis device 72 are arranged on the side wall of the outlet of the cyclone separator center tube 41, and the first flue gas analysis device 71 and the second flue gas analysis device 72 are simultaneously connected to the second PID controller 73. The first flue gas analysis device 71 is used to detect the nitrogen oxide concentration of the exhaust gas entering the front half of the central tube 41, and the second flue gas analysis device 72 is used to detect the nitrogen oxide concentration of the exhaust gas in the rear half of the central tube 41 to ensure that various pollutants in the exhaust gas meet the emission standards.

[0041] The lower bottom surface of the wind chamber 1 is provided with a primary air inlet 11, and the side of the wind chamber 1 is provided with an ammonia inlet 12; at least one secondary air inlet 21 is provided on the side wall of the furnace 2, and the position of the secondary air inlet 21 is slightly higher than the bed height of the bed material inside the furnace 2;

[0042] The near-cyclone separator end of the cyclone separator inlet flue 3 is respectively provided with at least one gas inlet 31 and a gas flow control valve 32, at least one air inlet 33 and an air flow control valve 34; and the gas inlet 31 and the air inlet 32 ​​are both connected to the cyclone separator inlet flue 3; the gas flow control valve 32 and the air flow control valve 34 are simultaneously connected to the first PID controller 52; the first PID controller 52 is used to control the opening of the gas flow control valve 32 and the air flow control valve 34.

[0043] At least one ammonia injection port 42 and a flow control valve 43 are provided on the side wall of the outlet of the cyclone separator central tube 41, between the first flue gas analysis device 71 and the second flue gas analysis device 72. The second PID controller 73 is also connected to the flow control valve 43, and is used to adjust the opening of the flow control valve 43 and thus control the ammonia injection flow rate.

[0044] In a specific application example, the gas inlet 31 and the air inlet 33 on the cyclone separator inlet flue 3 are arranged opposite to each other up and down, and the number is the same; or, the gas inlet 31 and the air inlet 33 are arranged alternately on the same side; and in a preferred embodiment, the number of the gas inlet 31 and the air inlet 33 is the same. When the gas and air are introduced separately, the gas and air can be directly mixed and mixed evenly.

[0045] Based on the above-mentioned circulating fluidized bed boiler, an embodiment of the present invention further provides an ammonia-blended combustion method for a circulating fluidized bed boiler. The method comprises:

[0046] In step S1, ammonia and primary air are mixed evenly in the wind chamber arranged at the lower part of the furnace, and then sent into the furnace, where they are burned with the participation of secondary air to generate high-temperature flue gas; the reducing atmosphere in the lower part of the furnace is maintained by adjusting the air volume of the primary air and the secondary air.

[0047] In this step, a combustion reaction occurs in the furnace. At this time, since ammonia replaces part of the coal, the generation and emission of carbon dioxide can be reduced, but the combustion of ammonia will bring more nitrogen oxide emissions. At this time, the high-temperature flue gas contains nitrogen oxides such as nitrous oxide. Maintaining a reducing atmosphere in the lower part of the furnace can minimize the generation of nitrogen oxides.

[0048] Step S2, the high-temperature flue gas after combustion in the furnace enters the inlet flue of the cyclone separator; at the same time, the gas and air introduced through the gas inlet and the air inlet are mixed; the high-temperature flue gas ignites the mixture of gas and air and mixes with it, and then enters the cyclone separator together.

[0049] In this step, the temperature of the high-temperature flue gas entering the inlet flue of the cyclone separator is sufficient to directly ignite the mixture of fuel gas and air entering the inlet flue of the cyclone separator. The fuel gas includes one or more of ammonia, hydrogen, and natural gas.

[0050] In step S3, the mixed gas burns inside the cyclone separator, and the thermocouple monitors the temperature inside the cyclone separator in real time and uploads the temperature to the first PID controller. At this time, the first PID controller adjusts the opening of the gas flow control valve and the air flow control valve to regulate the flow of gas and air introduced, so that the temperature inside the cyclone separator is maintained at 950-1000°C; at this temperature, nitrous oxide in the high-temperature flue gas discharged from the furnace is decomposed into nitrogen and oxygen.

[0051] In this step, in the cyclone separator, under the high temperature environment provided by the combustion of the mixed gas, the nitrous oxide generated and discharged in the furnace is decomposed, and the decomposition reaction is as follows:

[0052] 2N2O→2N2+O2

[0053] Through the above decomposition reaction, most of the nitrous oxide produced in the furnace is decomposed, thereby reducing pollution to the environment.

[0054] Step S4: under the action of the cyclone separator, the solid particles in the high-temperature flue gas are separated and returned to the furnace through the return device.

[0055] Step S5, the tail gas separated by the cyclone separator is discharged through the central tube of the cyclone separator.

[0056] The exhaust gas discharge process through the central tube of the cyclone separator specifically includes the following steps:

[0057] Step S51, in the front half of the central tube of the cyclone separator, the first flue gas analysis device analyzes the nitrogen oxide concentration in the exhaust gas, and uploads the detected nitrogen oxide concentration to the second PID controller. The second PID controller adjusts the opening of the flow control valve according to the nitrogen oxide concentration, so that the ammonia injected from the ammonia injection port fully reacts with the nitrogen oxides in the exhaust gas. After the nitrogen oxides are reduced, new exhaust gas is generated and enters the rear half of the central tube of the cyclone separator.

[0058] Step S52, in the second half of the cyclone separation center tube, the second flue gas analysis device analyzes the nitrogen oxide concentration in the exhaust gas again. If the detected nitrogen oxide concentration meets the emission standard, the exhaust gas is directly discharged; if the detected nitrogen oxide concentration does not meet the emission standard, the detected nitrogen oxide concentration is uploaded to the second PID controller. The second PID controller adjusts the opening of the flow control valve based on the two nitrogen oxide concentrations uploaded by the first flue gas analysis device and the second flue gas analysis device, and then regulates the nitrogen injection flow rate until the exhaust gas detected by the second flue gas analysis device meets the emission standard.

[0059] In this step, when the second PID controller integrates the two nitrogen oxide concentrations uploaded by the first flue gas analysis device and the second flue gas analysis device, it generally superimposes the ammonia flow rates required by the two corresponding ones, so as to achieve the purpose of making the nitrogen oxide react as completely as possible.

[0060] The circulating fluidized bed boiler and the ammonia-blended combustion method provided in the embodiments of the present invention are applied to the actual boiler operation process. Taking a 220 t / h circulating fluidized bed boiler as an example, the coal feed rate is 41.7 t / h.

[0061] When the circulating fluidized bed boiler and ammonia-blended combustion method of the present invention are used, 30% of the calorific value of coal is replaced by ammonia, and the ammonia flow rate is 12710Nm 3 / h, the primary air share is 55%, and the secondary air share is 45%, so that the bottom of the furnace is a reducing atmosphere. The temperature of the high-temperature flue gas entering the inlet flue of the cyclone separator is 810℃~860℃. In order to increase the temperature to at least 950℃, additional heat is required. This part of the heat is provided by the combustion of the corresponding gases introduced into the gas inlet and the air inlet respectively. The fuel gas used in this embodiment is ammonia, and the required amount of ammonia accounts for 15% to 25% of the total amount of ammonia. The flow rates of ammonia and air are adjusted in real time according to the detection value of the thermocouple. The amount of ammonia sprayed at the ammonia spray port at the outlet flue of the cyclone separator is adjusted in real time according to the detection value of the flue gas analysis device. The emission concentration of nitrogen oxides in this method is about 61mg / m 3 (Converted according to relevant standards), far below 100mg / m 3 The relevant standards, among which the emission of nitrous oxide is less than 10mg / m 3 , which is about 90% less than when burning pure coal

[0062] It can be seen from the above technical solutions that the circulating fluidized bed boiler and ammonia-blended combustion method provided in the embodiments of the present invention are simple and easy to implement improvements to the boiler. On the premise of improving the combustion efficiency of the fluidized bed, the emission of nitrogen oxides, especially nitrous oxide, is reduced during the circulating fluidized bed ammonia-blended combustion, thereby reducing environmental pollution.

[0063] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. It is not intended to limit the scope of the invention claimed for protection, but only represents the preferred embodiment of the present invention. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

Claims

1. A circulating fluidized bed boiler, characterized in that: The circulating fluidized bed boiler comprises: a wind chamber (1), a furnace (2), a cyclone separator inlet flue (3), a cyclone separator (4), a thermocouple (51), a first PID controller (52), and a material return device (6); The wind chamber (1) is arranged at the bottom of the furnace (2); the upper side of the furnace (2) is connected to the cyclone separator inlet flue (3); a thermocouple (51) is arranged inside the cyclone separator (4); the thermocouple (51) is connected to the first PID controller (52); and a material return device (6) is arranged at the lower end of the cyclone separator (4); The cyclone separator inlet flue (3) is provided with at least one gas inlet (31) and a gas flow control valve (32), at least one air inlet (33) and an air flow control valve (34) at the near-cyclone separator end; the gas inlet (31) and the air inlet (32) are both connected to the cyclone separator inlet flue (3); and the gas flow control valve (32) and the air flow control valve (34) are simultaneously connected to the first PID controller (51).

2. The circulating fluidized bed boiler according to claim 1, characterized in that: The gas inlet (31) and the air inlet (33) on the cyclone separator inlet flue (3) are arranged opposite to each other in the upper and lower directions.

3. The circulating fluidized bed boiler according to claim 1, characterized in that: The gas inlet (31) and the air inlet (33) on the cyclone separator inlet flue (3) are alternately arranged on the same side.

4. The circulating fluidized bed boiler according to claim 3, characterized in that: The number of the gas inlets (31) and the number of the air inlets (33) are the same.

5. The circulating fluidized bed boiler according to claim 1, characterized in that: The fuel gas is one or more of ammonia, hydrogen and natural gas.

6. The circulating fluidized bed boiler according to any one of claims 1 to 5, characterized in that: The boiler further comprises a first flue gas analysis device (71), a second flue gas analysis device (72) and a second PID controller (73); The first flue gas analysis device (71) and the second flue gas analysis device (72) are respectively arranged on the outlet side wall of the cyclone separator central cylinder (41) of the cyclone separator (4), and the second PID controller (73) is simultaneously connected to the first flue gas analysis device (71) and the second flue gas analysis device (72); At least one ammonia injection port (42) and a flow control valve (43) are also arranged on the side wall of the outlet of the central cylinder (41) of the cyclone separator between the first flue gas analysis device (71) and the second flue gas analysis device (72); the second PID controller (73) is also connected to the flow control valve (43).

7. The circulating fluidized bed boiler according to claim 6, characterized in that: A primary air inlet (11) is provided on the lower bottom surface of the wind chamber (1), and an ammonia inlet (12) is provided on the side of the wind chamber (1); at least one secondary air inlet (21) is provided on the side wall of the furnace (2), and the position of the secondary air inlet (21) is slightly higher than the bed height of the bed material in the furnace (2).

8. The circulating fluidized bed boiler according to claim 6, characterized in that: One or more second ammonia inlets (22) and second air inlets (23) are also provided on the side wall of the furnace (2) to adjust the combustion state in the furnace (2); the second ammonia inlet (22) and the second air inlet (23) are higher than the secondary air inlet (21).

9. A method for ammonia-blended combustion in a circulating fluidized bed boiler, characterized in that: The method is implemented based on the circulating fluidized bed boiler provided by any one of claims 1 to 8, comprising: Step S1, ammonia and primary air are mixed evenly in a wind chamber arranged at the lower part of the furnace, and then sent into the furnace for combustion; the air volume of the primary air and the secondary air is adjusted to maintain a reducing atmosphere at the lower part of the furnace; Step S2, the high-temperature flue gas generated after the combustion in the furnace enters the inlet flue of the cyclone separator; at the same time, the gas and air introduced through the gas inlet and the air inlet are mixed; the high-temperature flue gas ignites the mixture of gas and air and mixes with it, and then enters the cyclone separator together; Step S3, the mixed gas burns inside the cyclone separator, and the thermocouple monitors the temperature inside the cyclone separator in real time and uploads the temperature to the first PID controller. At this time, the first PID controller adjusts the opening of the gas flow control valve and the air flow control valve to accurately adjust the flow of gas and air introduced, so that the temperature inside the cyclone separator is maintained at 950-1000°C; at this temperature, nitrous oxide in the high-temperature flue gas is decomposed into nitrogen and oxygen; Step S4, under the action of the cyclone separator, the solid particles in the high-temperature flue gas are separated and returned to the furnace through the return device; Step S5, the tail gas separated by the cyclone separator is discharged through the central tube of the cyclone separator.

10. The ammonia-blended combustion method for a circulating fluidized bed boiler according to claim 9, characterized in that: Step S5 includes: Step S51, in the front half of the central cylinder of the cyclone separator, the first flue gas analysis device analyzes the concentration of nitrogen oxides in the tail gas, and uploads the detected concentration of nitrogen oxides to the second PID controller, and the second PID controller adjusts the opening of the flow control valve according to the concentration of nitrogen oxides, so that the ammonia injected from the ammonia injection port fully reacts with the nitrogen oxides in the tail gas, and the nitrogen oxides are reduced to generate new tail gas, which enters the rear half of the central cylinder of the cyclone separator; Step S52, in the second half of the cyclone separation center tube, the second flue gas analysis device analyzes the nitrogen oxide concentration in the exhaust gas again; if the detected nitrogen oxide concentration meets the emission standard, the exhaust gas is directly discharged; if the detected nitrogen oxide concentration does not meet the emission standard, the detected nitrogen oxide concentration is uploaded to the second PID controller, and the second PID controller adjusts the opening of the flow control valve based on the two nitrogen oxide concentrations uploaded by the first flue gas analysis device and the second flue gas analysis device, thereby controlling the nitrogen injection flow rate until the exhaust gas detected by the second flue gas analysis device meets the emission standard.

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