Denitration device and flue gas treatment system comprising same

Abstract

The utility model relates to the technical field of incineration flue gas treatment, in particular to a denitration device and a flue gas treatment system comprising the denitration device. The denitration device comprises a combustion furnace, a main denitration module and an auxiliary denitration module, the main denitration module comprises an ammonia water atomizing nozzle used for spraying ammonia water, the ammonia water atomizing nozzle is arranged in the combustion furnace, and a mixing and distributing mechanism used for controlling the concentration of the ammonia water is further arranged in the combustion furnace. The ammonia water atomizing nozzle is communicated with the mixing and distributing mechanism; the auxiliary denitration module is arranged outside the combustion furnace, a chimney used for discharging clean flue gas is arranged on the downstream of the auxiliary denitration module, and an induced draft fan is arranged between the chimney and the auxiliary denitration module. The flue gas denitration device has the effects of removing harmful pollutants in flue gas, flexibly adjusting the denitration efficiency and improving the operation compatibility of a flue gas treatment mechanism.

Description

Technical Field

[0001] The present application relates to the technical field of incineration flue gas treatment, and in particular to a denitrification device and a flue gas treatment system including the denitrification device. Background Art

[0002] Waste incineration flue gas treatment is an important topic in the field of environmental protection. As environmental protection standards become increasingly higher, high-standard purification of harmful gases generated during waste incineration is an urgent problem to be solved in the process of waste incineration. Currently, there are many technologies widely used to treat flue gas generated by waste incineration, such as denitrification technology, fly ash and fine glass powder treatment technology, dioxin control technology, dust removal technology, etc. In the relevant waste incineration flue gas treatment methods, the harmful substances in the flue gas will be removed in stages using corresponding technical means according to the different types of harmful substances in the flue gas.

[0003] More than 90% of NOX pollution discharged into the atmosphere comes from the fuel combustion process. The NOX generated during the waste incineration process comes from the decomposition and transformation of nitrogen-containing organic matter in the waste, and the other part comes from the NOX generated by nitrogen in the air under oxidizing atmosphere and high temperature conditions. There are many forms of NO, NO2, N20, N2O3, N207, etc.

[0004] According to the mechanism of nitrogen oxide generation, there is NOX that needs to be removed both inside and outside the combustion furnace. Selecting a single denitrification treatment process cannot flexibly adjust the denitrification efficiency, making the compatibility of the entire flue gas treatment mechanism poor and reducing the reliability of the mechanism's operation. Utility Model Content

[0005] In order to remove harmful pollutants in flue gas, flexibly adjust the denitrification efficiency, and improve the compatibility of the operation of the flue gas treatment mechanism, the present application provides a denitrification device and a flue gas treatment system including the denitrification device.

[0006] In the first aspect, the present application provides a denitration device, which adopts the following technical solution:

[0007] A denitration device, comprising a combustion furnace, a main denitration module, and an auxiliary denitration module, wherein the main denitration module comprises an ammonia atomizing nozzle for spraying ammonia water, the ammonia atomizing nozzle is arranged in the combustion furnace, and a mixing and distributing mechanism for controlling the concentration of ammonia water is also arranged in the combustion furnace, and the ammonia atomizing nozzle and the mixing and distributing mechanism are interconnected;

[0008] The auxiliary denitration module is arranged outside the combustion furnace, a chimney for discharging clean flue gas is arranged downstream of the auxiliary denitration module, and an induced draft fan is arranged between the chimney and the auxiliary denitration module.

[0009] By adopting the above technical solution, the ammonia atomizing nozzle can spray ammonia evenly and effectively into the flue gas in the combustion furnace, and the atomized ammonia reacts chemically with the nitrogen oxides in the flue gas, thereby effectively removing the nitrogen oxides and achieving efficient denitrification. The mixing and distribution mechanism set in the combustion furnace can accurately control the concentration of ammonia. The setting of the auxiliary denitrification module further enhances the denitrification effect. It can denitrify the flue gas treated by the main denitrification module again to ensure that the nitrogen oxide content in the flue gas meets the emission standards. The main denitrification module is set in the combustion furnace and can directly treat the generated flue gas, reducing the loss of flue gas during transmission. The auxiliary denitrification module is set outside the combustion furnace for easy maintenance and operation. The coordination between the main denitrification module and the auxiliary denitrification module enables the denitrification efficiency to be flexibly adjusted and improves the compatibility of the operation of the flue gas treatment mechanism.

[0010] Furthermore, the main denitrification module also includes an ammonia water storage tank and a dilution liquid storage tank, and the ammonia water storage tank and the dilution liquid storage tank are both arranged outside the combustion furnace, and the ammonia water storage tank and the dilution liquid storage tank are both connected to the mixing and distribution mechanism, and a first ammonia water delivery pump is arranged between the ammonia water storage tank and the mixing and distribution mechanism, and a dilution liquid delivery pump is arranged between the dilution liquid storage tank and the mixing and distribution mechanism.

[0011] By adopting the above technical solution, the setting of ammonia water storage tank and diluent storage tank ensures the continuous and stable supply of ammonia water and diluent. This helps the main denitrification module to always maintain a stable denitrification efficiency during long-term operation. When it is necessary to adjust the denitrification efficiency or treat flue gas of different concentrations, the delivery volume of the delivery pump can be adjusted. The storage and delivery systems of ammonia water and diluent are relatively independent and have high flexibility.

[0012] Furthermore, the auxiliary denitrification module includes a denitrification tower, an ammonia evaporation mixer and a second ammonia delivery pump. The denitrification tower contains a catalyst. The ammonia evaporation mixer is connected to the top of the denitrification tower. The second ammonia delivery pump is arranged on the side of the ammonia evaporation mixer away from the denitrification tower. The second ammonia delivery pump is connected to the ammonia storage tank for delivering ammonia to the ammonia evaporation mixer.

[0013] By adopting the above technical solution, the catalyst can make ammonia react with nitrogen oxides first instead of oxygen, while also reducing the reaction activity. Under the action of the catalyst, ammonia and nitrogen oxides in the flue gas undergo an oxidation-reduction reaction, converting nitrogen oxides into nitrogen and water for removal, thereby improving the denitrification efficiency. The setting of the second ammonia delivery pump ensures that ammonia can be stably and continuously delivered to the ammonia evaporation mixer. The connection design between the ammonia evaporation mixer and the denitrification tower allows ammonia to be fully mixed with air before entering the denitrification tower to form uniform ammonia vapor, ensuring that ammonia can evenly contact and react with nitrogen oxides in the flue gas, thereby achieving a better denitrification effect.

[0014] Furthermore, the auxiliary denitration module also includes an ammonia spraying grid, which is arranged above the denitration tower and is connected to the ammonia water evaporation mixer.

[0015] By adopting the above technical solution, the ammonia spray grid can evenly spray ammonia vapor into the denitrification tower to ensure sufficient contact between ammonia and nitrogen oxides in the flue gas. This uniform distribution can maximize the reaction efficiency of ammonia and nitrogen oxides. Since ammonia vapor can evenly cover the catalyst in the denitrification tower, the activity of the catalyst can be fully utilized, further promoting the reaction between ammonia and nitrogen oxides and improving the denitrification efficiency of the entire system.

[0016] Furthermore, a steam heater for heating the flue gas is provided upstream of the ammonia injection grid.

[0017] By adopting the above technical solutions, the appropriate flue gas temperature helps the catalyst to exert its best activity, thereby more effectively promoting the reaction of ammonia and nitrogen oxides. The setting of the steam heater can ensure that the flue gas reaches the optimal reaction temperature before entering the denitrification tower, optimizing the reaction environment. Heating the flue gas by the steam heater can increase the temperature of the flue gas, thereby increasing the reaction rate of ammonia and nitrogen oxides. Under high temperature conditions, the reaction between ammonia and nitrogen oxides is more active, thereby improving the denitrification efficiency.

[0018] In the second aspect, the present application provides a flue gas treatment system, which adopts the following technical solution:

[0019] A flue gas treatment system, comprising the denitration device as described in the first aspect, further comprising a semi-dry deacidification device and a dust removal device, wherein the semi-dry deacidification device is connected to the downstream of the combustion furnace, and the dust removal device is connected to the downstream of the semi-dry deacidification device, and the deacidification device comprises a semi-dry reaction tower, and a lime slurry mixing bin and a rotary atomizing nozzle are arranged on the top of the semi-dry reaction tower, and the rotary atomizing nozzle is connected to the lime slurry mixing bin, and the flue gas flows from top to bottom in the semi-dry reaction tower, and the lime slurry flows downward through the rotary atomizing nozzle for co-flow deacidification with the flue gas;

[0020] The dust removal device is arranged downstream of the semi-dry deacidification device.

[0021] By adopting the above technical solutions, the denitrification device can reduce the nitrogen oxide content in the flue gas and effectively prevent the pollution of the atmospheric environment. The semi-dry deacidification device can remove the acidic gas in the flue gas through the co-flow deacidification of lime slurry and flue gas. The rotary atomizing nozzle allows the lime slurry to be sprayed evenly and finely in the flue gas, increasing the reaction area and improving the deacidification efficiency. The dust removal device can effectively remove particulate matter in the flue gas, further improving the quality of flue gas treatment.

[0022] Furthermore, the dust removal device includes a bag dust collector and a dry powder mixer, the dry powder mixer is arranged between the semi-dry deacidification device and the bag dust collector, and the bag dust collector and the dry powder mixer are interconnected.

[0023] By adopting the above technical solution, the bag filter can effectively remove the particles in the flue gas. Through the filtering effect of the bag, the particles in the flue gas are trapped on the bag, thereby achieving the dust removal effect. The dry powder mixer can further mix and absorb the fine particles in the flue gas before the flue gas enters the bag filter, thereby improving the dust removal efficiency of the bag filter.

[0024] Furthermore, the dry powder mixer is connected to an activated carbon adsorption device, which includes an activated carbon bin, an activated carbon conveyor and an activated carbon injector. The activated carbon conveyor is interconnected with the activated carbon bin and the activated carbon injector, and the end of the activated carbon injector away from the activated carbon conveyor is connected to the dry powder mixer.

[0025] By adopting the above technical solution, the activated carbon conveyor can realize the continuous transportation of activated carbon from the activated carbon bin to the activated carbon injector, ensuring the stable supply of activated carbon. By adjusting the conveying volume of the activated carbon conveyor, the dosage of activated carbon can be flexibly controlled to meet the treatment needs of flue gas with different concentrations. The adsorption effect of activated carbon and the mixing effect of dry powder complement each other, jointly improving the dust removal efficiency and effectively removing particulate matter and harmful substances in the flue gas. Activated carbon has adsorption properties and can adsorb various harmful substances such as organic pollutants and heavy metal ions in the flue gas, further improving the removal rate of harmful substances in the flue gas, thereby improving the quality of flue gas.

[0026] Furthermore, the dry powder mixer is connected to a dry spray deacidification device, which includes a lime powder bin, a lime powder conveyor and a lime powder injector. The lime powder conveyor is connected to the lime powder bin and the lime powder injector, and the end of the lime powder injector away from the lime powder conveyor is connected to the dry powder mixer.

[0027] By adopting the above technical solution, the dry-jet deacidification device directly sprays lime powder into the dry powder mixer through the lime powder injector, and reacts quickly with the acid gas in the flue gas. As an effective deacidification agent, lime powder can react chemically with sulfur oxides and nitrogen oxides in the acid gas to generate solid waste, thereby greatly reducing the acid gas content in the flue gas. This direct injection method makes the deacidification reaction faster and more efficient. The dry-jet deacidification device works in conjunction with the dry powder mixer and the previous deacidification and dust removal devices to form a complete flue gas purification process. The design of the lime powder conveyor allows the supply of lime powder to be flexibly adjusted. According to the concentration of acid gases in the flue gas and the treatment requirements, the delivery amount of lime powder can be adjusted to achieve precise control of the deacidification effect. This adjustability enables the system to adapt to different working conditions and treatment requirements, improving the adaptability and flexibility of the system.

[0028] In summary, the present application includes at least one of the following beneficial technical effects:

[0029] 1. The operation mode of the denitrification system is a combination of in-furnace main denitrification + external auxiliary denitrification, and the reductant flow rate during operation is about 36L / h. The amount of ammonia water (20% concentration) used per ton of garbage is 2.62kg, the price of 20% ammonia water is 1,300 yuan / ton, and the cost of ammonia water per ton of garbage is 3.4 yuan. Compared with the use of SNCR denitrification alone, when nitrogen oxides are controlled at around 75mg / m3, the flow rate of the ammonia water mixture of SNCR denitrification sprayed into the furnace is about 200L / h, the amount of ammonia water (20% concentration) used per ton of garbage is about 8kg, and the cost of ammonia water per ton of garbage is 10.4 yuan. Compared with the use of external denitrification alone, the in-furnace main denitrification + external auxiliary denitrification group mode can save about 2 / 3 of the raw materials, save about 7 yuan in ammonia water cost per ton of garbage, and significantly save the cost of environmental protection consumables;

[0030] 2. The comprehensive flue gas treatment system purifies the toxic and harmful flue gas generated by garbage disposal to prevent pollution to the environment. The combined flue gas purification process of "main denitrification mechanism + semi-dry deacidification mechanism + activated carbon adsorption mechanism + dry jet deacidification mechanism + bag dust removal mechanism + auxiliary denitrification mechanism" has high flue gas treatment standards and the design emission limits are better than the national standards and relevant EU standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of a flue gas treatment system according to an embodiment of the present application.

[0032] Figure 2 It is a schematic diagram of the overall structure of the semi-dry deacidification device in the embodiment of the present application.

[0033] Figure 3 It is a schematic diagram of the overall structure of the dust removal device in the embodiment of the present application.

[0034] Figure 4 It is a schematic diagram of the overall structure of the steam heater in the embodiment of the present application.

[0035] Explanation of reference numerals: 1. Combustion furnace; 2. Main denitration module; 21. Ammonia atomizing nozzle; 22. Mixing and distributing mechanism; 23. Ammonia storage tank; 231. First ammonia delivery pump; 232. Second ammonia delivery pump; 24. Dilution storage tank; 241. Dilution delivery pump; 3. Auxiliary denitration module; 31. Denitration tower; 311. Catalyst; 32. Ammonia evaporation mixer; 33. Ammonia spraying grid; 34. Steam heater; 4. Semi-dry 41. Semi-dry reaction tower; 42. Lime slurry mixing bin; 43. Rotary atomizing nozzle; 5. Dust removal device; 51. Bag filter; 52. Dry powder mixer; 6. Activated carbon adsorption device; 61. Activated carbon bin; 62. Activated carbon conveyor; 63. Activated carbon injector; 7. Dry injection deacidification device; 71. Lime powder bin; 72. Lime powder conveyor; 73. Lime powder injector; 8. Chimney; 81. Draft fan. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-4 And embodiments, the present application is further described in detail.

[0037] The present application embodiment discloses a flue gas treatment system. Figure 1 The comprehensive flue gas treatment system includes a combustion furnace 1, a denitrification device, a semi-dry deacidification device 4, an activated carbon adsorption device 6, a dry injection deacidification device 7, a bag dust removal device 5 and a chimney 8 for discharging clean flue gas.

[0038] The denitration device includes a main denitration module 2 for removing NOX inside the combustion furnace 1, and an auxiliary denitration module 3 for removing NOX outside the combustion furnace 1. The main denitration module 2 in this embodiment is SNCR (selective non-catalytic reduction denitration), and the main denitration module 2 includes a mixing and distribution module and an ammonia atomizing nozzle 21 arranged in the combustion furnace 1, and an ammonia storage tank 23 and a diluent storage tank 24 arranged outside the combustion furnace 1, and the ammonia storage tank 23 and the diluent storage tank 24 are both connected to the mixing and distribution module in the combustion furnace 1. A first ammonia delivery pump 231 is arranged between the ammonia storage tank 23 and the combustion furnace 1, and a diluent delivery pump 241 is arranged between the diluent storage tank 24 and the combustion furnace 1. The first ammonia delivery pump 231 delivers the ammonia in the ammonia storage tank 23 to the mixing and distribution module, and the diluent delivery pump 241 delivers the diluent in the diluent storage tank 24 to the mixing and distribution module, and the mixing and distribution module is in the combustion furnace 1 for proportional distribution to configure the ammonia diluent. The ammonia water atomizing nozzle 21 is disposed below the mixing and distributing module and is communicated with the mixing and distributing module. The ammonia water atomizing nozzle 21 atomizes and sprays the ammonia water dilution liquid to remove NOX generated inside the furnace body.

[0039] Reference Figure 1 and Figure 2 The semi-dry deacidification device 4 includes a semi-dry reaction tower 41 , and the flue gas discharged from the main denitration module 2 enters the semi-dry deacidification device 4 from the upper part of the semi-dry reaction tower 41 .

[0040] A lime slurry mixing bin 42 is provided above the semi-dry reaction tower 41, and a rotary atomizing nozzle 43 is provided at the top of the semi-dry reaction tower 41. The lime slurry mixing bin 42 and the rotary atomizing nozzle 43 are connected to each other. The flue gas flows from top to bottom inside the semi-dry reaction tower 41 and is discharged from the bottom of the dry reaction tower. The lime slurry mixing bin 42 transports the lime slurry to the rotary atomizing nozzle 43, and the rotary atomizing nozzle 43 sprays the lime slurry downward into the flue gas. The lime slurry and the flue gas are mixed and flowed in the semi-dry reaction tower 41 to achieve the effect of deacidification.

[0041] Reference Figure 1 and Figure 3 The flue gas discharged from the bottom of the semi-dry reaction tower 41 enters the bag dust removal device 5, which includes a bag dust collector 51 and a dry powder mixer 52. The dry powder mixer 52 is arranged between the semi-dry reaction tower 41 and the bag dust collector 51, and the dry powder mixer 52 is interconnected with the semi-dry reaction tower 41 and the bag dust collector 51.

[0042] The dry powder mixer 52 is also connected to an activated carbon adsorption device 6 and a dry injection deacidification device 7. The activated carbon adsorption device 6 includes an activated carbon bin 61, an activated carbon conveyor 62, and an activated carbon injector 63. The activated carbon conveyor 62 is arranged between the activated carbon bin 61 and the activated carbon injector 63 and is interconnected with both. One end of the activated carbon injector 63 away from the activated carbon conveyor 62 is connected to the dry powder mixer 52. The activated carbon conveyor 62 conveys the activated carbon powder in the activated carbon bin 61 to the activated carbon injector 63, and the activated carbon injector 63 uniformly injects the activated carbon powder into the flue gas to increase the contact area between the activated carbon and the flue gas, so as to adsorb heavy metals such as Pb and Hg, organic pollutants such as dioxins and furans, and heavy metal ions.

[0043] The dry spray deacidification device 7 includes a lime powder bin 71, a lime powder conveyor 72 and a lime powder injector 73. The lime powder conveyor 72 is arranged between the lime powder bin 71 and the lime powder injector 73 and is interconnected with both. The end of the lime powder injector 73 away from the lime powder conveyor 72 is connected to the dry powder mixer 52. The lime powder conveyor 72 conveys the lime powder in the lime powder bin 71 to the lime powder injector 73, and the lime powder injector 73 uniformly injects the lime powder into the flue gas, thereby increasing the contact area between the lime powder and the flue gas and improving the deacidification efficiency. As a commonly used deacidification agent, lime powder can effectively react with acidic substances in the flue gas, thereby reducing the content of acidic components in the flue gas.

[0044] In the reaction of the semi-dry deacidification device 4, the moisture in the droplets is dried and evaporated by the flue gas, and the final reaction product is a dry powder, the main components of which are CaCl2, CaSO3, CaSO4, Ca(OH)2 and smoke, which are collected by the bag dust removal device 5.

[0045] In the reaction of the dry injection deacidification device 7, the lime powder reacts with the flue gas to form a dry powder, the main components of which are CaCl2, CaSO3, CaSO4, residual Ca(OH)2 and smoke dust. The activated carbon powder enters the dry powder mixer 52 with the dry powder so as to be intercepted by the bag filter 51.

[0046] Reference Figure 1 and Figure 4, the flue gas discharged from the bag dust removal device 5 enters the steam heater 34, and enters the auxiliary denitration module 3 after being discharged from the steam heater 34. The auxiliary denitration module 3 includes a denitration tower 31, and the denitration tower 31 is filled with a catalyst 311. The auxiliary denitration module 3 in this embodiment is an SCR (selective catalytic reduction). Under the action of the catalyst 311, an amino reductant is used to "selectively" react with NOX in the flue gas to generate nitrogen and water. An ammonia evaporation mixer 32 and a second ammonia delivery pump 232 are arranged outside the denitration tower 31. The second ammonia delivery pump 232 is interconnected with the ammonia storage tank 23 and the ammonia evaporation mixer 32. The second ammonia delivery pump 232 delivers the ammonia in the ammonia storage tank 23 to the ammonia evaporation mixer 32. An ammonia spraying grid 33 is arranged between the steam heater 34 and the denitration tower 31.

[0047] The flue gas discharged from the steam heater 34 enters the denitrification tower 31 from the top and is discharged from the bottom of the denitrification tower 31. The second ammonia delivery pump 232 delivers ammonia to the ammonia evaporation mixer 32. Superheated steam is introduced into the ammonia evaporation mixer 32 to make the ammonia gaseous. The flue gas and ammonia are mixed at the position of the ammonia spray grid 33 and flow into the top of the denitrification tower 31. The catalyst 311 makes ammonia react with nitrogen oxides first instead of oxygen, while also reducing the reaction activity. Under the action of the catalyst 311, ammonia and NOX in the flue gas undergo an oxidation-reduction reaction, converted into nitrogen and water, and thus removed.

[0048] The implementation principle of a flue gas treatment system in the embodiment of the present application is as follows: the flue gas generated by the combustion furnace 1 is firstly treated by the main denitration module 2. The main denitration module 2 adopts the selective non-catalytic reduction denitration (SNCR) technology, and the ammonia water and the diluent are mixed in proportion to form an ammonia water diluent through the mixing and distribution module, and then atomized through the ammonia water atomization nozzle 21 and sprayed into the combustion furnace 1 to react with NOX in the flue gas, thereby removing part of the nitrogen oxides.

[0049] The flue gas treated by the main denitration module 2 enters the semi-dry deacidification device 4. The semi-dry deacidification device 4 uses lime slurry to react with acidic substances in the flue gas to achieve the purpose of deacidification. The lime slurry is evenly sprayed into the semi-dry reaction tower 41 through a rotary atomizing nozzle 43, mixed with the flue gas and flowed together to achieve the deacidification effect.

[0050] The flue gas treated by the semi-dry deacidification device 4 enters the bag dust collector 5. The bag dust collector 5 further improves the flue gas purification effect by setting a dry powder mixer 52, combining an activated carbon adsorption device 6 and a dry spray deacidification device 7. The activated carbon adsorption device 6 evenly sprays activated carbon powder into the flue gas through an activated carbon injector 63 to adsorb heavy metals and organic pollutants; the dry spray deacidification device 7 evenly sprays lime powder into the flue gas through a lime powder injector 73 to react with acidic substances to improve the deacidification efficiency.

[0051] The flue gas treated by the bag filter 5 enters the steam heater 34 for heating. The heated flue gas enters the auxiliary denitration module 3, i.e., the selective catalytic reduction (SCR) denitration system. In the auxiliary denitration module 3, the ammonia water is transformed into a gaseous state through the ammonia water evaporation mixer 32 and mixed with the flue gas at the ammonia spray grid 33. Under the action of the catalyst 311, the ammonia gas undergoes an oxidation-reduction reaction with the NOX in the flue gas, further removing the remaining nitrogen oxides.

[0052] The clean flue gas treated by the flue gas treatment system is discharged into the atmosphere through the induced draft fan 81 and the chimney 8. The entire flue gas treatment system achieves comprehensive treatment of nitrogen oxides, acidic substances, heavy metals and organic pollutants in the flue gas through the synergistic effect of multiple links, ensuring that the discharged flue gas meets environmental protection standards and protects the atmospheric environment.

[0053] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A denitration device, characterized in that: The invention comprises a combustion furnace (1), a main denitration module (2), and an auxiliary denitration module (3); the main denitration module (2) comprises an ammonia water atomizing nozzle (21) for spraying ammonia water; the ammonia water atomizing nozzle (21) is arranged in the combustion furnace (1); a mixing and distributing mechanism (22) for controlling the concentration of ammonia water is also arranged in the combustion furnace (1); the ammonia water atomizing nozzle (21) and the mixing and distributing mechanism (22) are interconnected; The auxiliary denitration module (3) is arranged outside the combustion furnace (1), a chimney (8) for discharging clean flue gas is arranged downstream of the auxiliary denitration module (3), and an induced draft fan (81) is arranged between the chimney (8) and the auxiliary denitration module (3).

2. The denitration device according to claim 1, characterized in that: The main denitration module (2) further comprises an ammonia water storage tank (23) and a diluent storage tank (24), wherein the ammonia water storage tank (23) and the diluent storage tank (24) are both arranged outside the combustion furnace (1), and the ammonia water storage tank (23) and the diluent storage tank (24) are both connected to the mixing and distribution mechanism (22), and a first ammonia water delivery pump (231) is arranged between the ammonia water storage tank (23) and the mixing and distribution mechanism (22), and a diluent delivery pump (241) is arranged between the diluent storage tank (24) and the mixing and distribution mechanism (22).

3. The denitration device according to claim 2, characterized in that: The auxiliary denitration module (3) comprises a denitration tower (31), an ammonia water evaporation mixer (32) and a second ammonia water delivery pump (232); a catalyst (311) is contained in the denitration tower (31); the ammonia water evaporation mixer (32) is connected to the top of the denitration tower (31); the second ammonia water delivery pump (232) is arranged on a side of the ammonia water evaporation mixer (32) away from the denitration tower (31); the second ammonia water delivery pump (232) is connected to the ammonia water storage tank (23) for delivering ammonia water to the ammonia water evaporation mixer (32).

4. The denitration device according to claim 3, characterized in that: The auxiliary denitration module (3) further comprises an ammonia spraying grid (33), wherein the ammonia spraying grid (33) is arranged above the denitration tower (31), and the ammonia spraying grid (33) is connected to the ammonia water evaporation mixer (32).

5. The denitration device according to claim 4, characterized in that: A steam heater (34) for heating flue gas is arranged upstream of the ammonia injection grid (33).

6. A flue gas treatment system, characterized in that: A denitration device according to any one of claims 1 to 5, further comprising a semi-dry deacidification device (4) and a dust removal device (5), wherein the semi-dry deacidification device (4) is connected to the downstream of the combustion furnace (1), and the dust removal device (5) is connected to the downstream of the semi-dry deacidification device (4), wherein the deacidification device comprises a semi-dry reaction tower (41), and a lime slurry mixing bin (42) and a rotary atomizing nozzle (43) are arranged on the top of the semi-dry reaction tower (41), wherein the rotary atomizing nozzle (43) is connected to the lime slurry mixing bin (42), and the flue gas flows from top to bottom in the semi-dry reaction tower (41), and the lime slurry flows downward through the rotary atomizing nozzle (43) for co-flow deacidification with the flue gas; The dust removal device (5) is arranged downstream of the semi-dry deacidification device (4).

7. The flue gas treatment system according to claim 6, characterized in that: The dust removal device (5) comprises a bag dust collector (51) and a dry powder mixer (52), wherein the dry powder mixer (52) is arranged between the semi-dry deacidification device (4) and the bag dust collector (51), and the bag dust collector (51) and the dry powder mixer (52) are interconnected.

8. The flue gas treatment system according to claim 7, characterized in that: The dry powder mixer (52) is connected to an activated carbon adsorption device (6), and the activated carbon adsorption device (6) comprises an activated carbon bin (61), an activated carbon conveyor (62) and an activated carbon injector (63). The activated carbon conveyor (62) is interconnected with the activated carbon bin (61) and the activated carbon injector (63), and one end of the activated carbon injector (63) away from the activated carbon conveyor (62) is connected to the dry powder mixer (52).

9. The flue gas treatment system according to claim 7, characterized in that: The dry powder mixer (52) is connected to a dry spray deacidification device (7), and the dry spray deacidification device (7) comprises a lime powder bin (71), a lime powder conveyor (72), and a lime powder injector (73). The lime powder conveyor (72) is connected to the lime powder bin (71) and the lime powder injector (73). The end of the lime powder injector (73) away from the lime powder conveyor (72) is connected to the dry powder mixer (52).

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