A device capable of preventing corrosion of a waste heat boiler SCR denitration system

Abstract

The utility model discloses a device can prevent the corrosion of waste heat boiler SCR denitration system, ammonia water pipeline communicates with ammonia evaporator, and is installed with ammonia water pipeline entrance flowmeter, ammonia water pipeline entrance valve and ammonia injection valve in proper order along the water inlet to the water outlet direction of ammonia water pipeline, the air outlet of first air pipeline communicates to the ammonia water pipeline between ammonia injection valve and ammonia water pipeline water outlet, and the air outlet of hot flue gas pipeline communicates with the air inlet of ammonia evaporator, the air outlet of second air pipeline communicates to the hot flue gas pipeline between the air inlet of hot flue gas pipeline and dilution fan inlet valve, and nitrogen pipeline communicates to the ammonia water pipeline between ammonia water pipeline entrance valve and ammonia injection valve, and is installed with anticorrosive nitrogen gas primary valve, anticorrosive nitrogen gas check valve and anticorrosive nitrogen gas secondary valve in proper order along the air inlet to the air outlet direction of nitrogen pipeline, the device will stay in the SCR denitration system after the shutdown of furnace and the ammonia water and air replacement that do not react completely are replaced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of gas technology, specifically a device that can prevent corrosion in the SCR denitrification system of a waste heat boiler. Background Technology

[0002] In industrial production processes, especially during fuel combustion, large amounts of nitrogen oxides (NOx) are produced, posing a serious threat to the environment and human health. To reduce the emission of these harmful gases, denitrification technology has emerged. The working principle of an SCR denitrification system: SCR, or Selective Catalytic Reduction, uses a suitable catalyst at a specific temperature to convert nitrogen oxides into harmless nitrogen and water vapor using ammonia as the reducing agent. Currently, the reducing agent used for flue gas SCR denitrification is mainly ammonia water, and the widely used catalysts use titanium dioxide (TiO2) as a carrier and vanadium pentoxide (V2O5) and tungsten trioxide (WO3) as active components.

[0003] SCR denitrification system equipment includes: ammonia evaporator, fan, ammonia injection grid, SCR reactor, etc. As a highly efficient and environmentally friendly denitrification method, SCR denitrification system has gradually gained widespread application and recognition. However, after the waste heat boiler is shut down, some ammonia water and air remain in the ammonia evaporator of the SCR denitrification system, which can cause corrosion of the SCR denitrification system. During daily operation of the denitrification system, problems such as ammonia water leakage sometimes occur.

[0004] To address the aforementioned issues, a device is proposed to prevent corrosion in the SCR denitrification system of a waste heat boiler, thereby avoiding personnel hazards and equipment damage caused by corrosion and leakage of the SCR denitrification system. Utility Model Content

[0005] The purpose of this invention is to provide a device that can prevent corrosion in the SCR denitrification system of a waste heat boiler, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a device for preventing corrosion in a waste heat boiler SCR denitrification system, comprising an ammonia evaporator, an ammonia water pipeline, a first air pipeline, a hot flue gas pipeline, a second air pipeline, and a nitrogen pipeline.

[0007] The outlet of the ammonia water pipeline is connected to the inlet of the ammonia evaporator. Along the ammonia water pipeline from the inlet to the outlet, an ammonia water pipeline inlet flow meter, an ammonia water pipeline inlet valve, and an ammonia injection valve are installed in sequence.

[0008] The outlet of the first air pipeline is connected to the ammonia water pipeline between the ammonia injection valve and the outlet of the ammonia water pipeline. On the first air pipeline, an air inlet main valve and an air valve are installed sequentially from the air inlet to the air outlet.

[0009] The outlet of the hot flue gas pipeline is connected to the inlet of the ammonia evaporator. Along the hot flue gas pipeline, a dilution fan inlet valve, a dilution fan, and a dilution fan outlet valve are installed in sequence from the inlet to the outlet.

[0010] The outlet of the second air duct is connected to the hot flue gas duct between the inlet of the hot flue gas duct and the inlet valve of the dilution fan. On the second air duct, a cooling fan inlet valve, a cooling fan and a cooling fan outlet valve are installed sequentially from the inlet to the outlet of the second air duct.

[0011] The outlet of the nitrogen pipeline is connected to the ammonia water pipeline between the inlet valve of the ammonia water pipeline and the ammonia injection valve. On the nitrogen pipeline, a corrosion-resistant primary nitrogen valve, a corrosion-resistant nitrogen check valve, and a corrosion-resistant secondary nitrogen valve are installed sequentially from the inlet to the outlet.

[0012] Furthermore, the ammonia water pipeline between the inlet valve and the outlet of the ammonia water pipeline is provided with at least two ammonia water pipeline branches, and each ammonia water pipeline branch is equipped with a corresponding ammonia injection valve.

[0013] Furthermore, the first air pipeline between the main air inlet valve and the outlet of the first air pipeline is provided with first air pipeline branches corresponding to the number of branches of the ammonia water pipeline, and each first air pipeline branch is equipped with an air valve.

[0014] Furthermore, the second air duct includes an air main pipe, a second air duct main pipe, and a second air duct branch pipe.

[0015] The air outlet of the main air pipe is connected to the air inlet of the second air duct branch pipe through the first connector, and the air inlet of the second air duct main pipe is connected to the air outlet of the second air duct branch pipe through the second connector. There are at least two second air duct branches, and on each second air duct branch, a cooling fan inlet valve, a cooling fan, and a cooling fan outlet valve are installed sequentially along the direction from the air inlet to the air outlet.

[0016] Furthermore, the hot flue gas pipeline includes a first main flue gas pipeline, a branch flue gas pipeline, and a second main flue gas pipeline.

[0017] The outlet of the first flue gas duct main is connected to the inlet of the flue gas duct branch pipe via a third connector, the outlet of the flue gas duct branch pipe is connected to the inlet of the second flue gas duct main via a fourth connector, and the outlet of the second flue gas duct main is connected to the inlet of the ammonia evaporator.

[0018] The flue gas duct has at least two branches, and each branch is equipped with a dilution fan inlet valve, a dilution fan, and a dilution fan outlet valve along the direction from the inlet to the outlet.

[0019] The outlet of the second air duct main is connected to the first flue gas duct main via a fifth connector.

[0020] Furthermore, a device that can prevent corrosion in a waste heat boiler SCR denitrification system also includes an ammonia tank, an ammonia pump, an ammonia injection grid, and an SCR reactor.

[0021] The ammonia tank is used to store ammonia. The outlet of the ammonia pump is connected to the inlet of the ammonia pipeline. The ammonia pump sends the ammonia in the ammonia tank to the ammonia evaporator and then into the ammonia spraying grid for uniform spraying. The ammonia flows upward to the SCR reactor to react with the hot flue gas.

[0022] Furthermore, an apparatus for preventing corrosion in a waste heat boiler SCR denitrification system also includes an air pump connected to a first air line, the air pump being used to power the air in the first air line.

[0023] A waste heat boiler includes a device for preventing corrosion of the waste heat boiler's SCR denitrification system.

[0024] Analysis shows that this utility model provides a device for preventing corrosion of the SCR denitrification system of a waste heat boiler, including an ammonia evaporator, an ammonia water pipeline, a first air pipeline, a hot flue gas pipeline, a second air pipeline, and a nitrogen pipeline.

[0025] The outlet of the ammonia water pipeline is connected to the inlet of the ammonia evaporator. Along the ammonia water pipeline from the inlet to the outlet, an ammonia water inlet flow meter, an ammonia water inlet valve, and an ammonia injection valve are installed in sequence. The ammonia water passes through the ammonia water inlet flow meter, the ammonia water inlet valve, and the ammonia injection valve in sequence and finally enters the ammonia evaporator. The ammonia water inlet valve has a rapid opening and closing function and a flow regulation function to ensure that the ammonia water source can be cut off in time in emergency situations, and that the ammonia water inlet flow meter can accurately measure the amount of ammonia water. Finally, the ammonia water is injected into the ammonia evaporator through the ammonia injection valve.

[0026] The air outlet of the first air pipeline is connected to the ammonia water pipeline between the ammonia injection valve and the ammonia water pipeline outlet. Air is delivered to the ammonia water pipeline through the first air pipeline to ensure that the ammonia water can enter the ammonia evaporator in a spray form.

[0027] On the first air pipeline, an air inlet main valve and an air valve are installed sequentially from the air inlet to the air outlet. The air inlet main valve controls the opening and closing of the first air pipeline, and the air valve further controls the air entering the ammonia water pipeline.

[0028] The outlet of the hot flue gas pipeline is connected to the inlet of the ammonia evaporator. Along the hot flue gas pipeline, a dilution fan inlet valve, a dilution fan, and a dilution fan outlet valve are installed sequentially from the inlet to the outlet. The hot flue gas in the hot flue gas pipeline is sent to the ammonia evaporator by the dilution fan to heat the atomized ammonia water, thereby increasing the temperature of the atomized ammonia water and improving the denitrification efficiency.

[0029] The outlet of the second air duct is connected to the hot flue gas duct between the inlet of the hot flue gas duct and the inlet valve of the dilution fan. On the second air duct, a cooling fan inlet valve, a cooling fan, and a cooling fan outlet valve are installed sequentially from the inlet to the outlet. The cooling fan cools the flue gas drawn by the dilution fan to prevent the ammonia water entering the ammonia evaporator from being too hot, which would affect the denitrification efficiency.

[0030] The outlet of the nitrogen pipeline is connected to the ammonia water pipeline between the inlet valve of the ammonia water pipeline and the ammonia injection valve. On the nitrogen pipeline, a corrosion-resistant primary nitrogen valve, a corrosion-resistant nitrogen check valve, and a corrosion-resistant secondary nitrogen valve are installed sequentially from the inlet to the outlet.

[0031] After the waste heat boiler SCR denitrification system is shut down, nitrogen gas in the nitrogen pipeline is used to replace the ammonia water and air that have not fully reacted in the SCR denitrification system after the shutdown, thereby extending the service life of the equipment.

[0032] Compared with the closest existing technology, the technical solution provided by this utility model has the following advantages: In response to the problem that residual ammonia water and air in the ammonia evaporator of the SCR denitrification system after the waste heat boiler is shut down, which can cause corrosion of the SCR denitrification system, this utility model replaces the residual ammonia water and air in the denitrification system through a nitrogen pipeline, thereby preventing corrosion and leakage of the denitrification system. Attached Figure Description

[0033] Figure 1This is a schematic diagram of a device for preventing corrosion in a waste heat boiler SCR denitrification system, as an example of this utility model.

[0034] In the diagram: 1. Ammonia evaporator; 2. Ammonia water pipeline; 21. Ammonia water pipeline branch pipe; 22. Ammonia water pipeline inlet flow meter; 23. Ammonia water pipeline inlet valve; 24. Ammonia injection valve; 3. First air pipeline; 31. Air inlet main valve; 32. Air valve; 33. First air pipeline branch pipe; 4. Hot flue gas pipeline; 41. Dilution fan inlet valve; 42. Dilution fan; 43. Dilution fan outlet valve; 44. First flue gas pipeline main pipe; 45. Flue gas pipeline branch pipe; 46. Second flue gas duct branch; 47. Third joint; 48. Fourth joint; 49. Fifth joint; 5. Second air duct; 51. Cooling fan inlet valve; 52. Cooling fan; 53. Cooling fan outlet valve; 54. Main air duct; 56. Second main air duct; 55. Second air duct branch; 57. First joint; 58. Second joint; 6. Nitrogen duct; 61. Corrosion-resistant primary nitrogen valve; 62. Corrosion-resistant nitrogen check valve; 63. Corrosion-resistant secondary nitrogen valve. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] It should be noted that in the description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0037] Furthermore, it should be understood that, for ease of description, the dimensions of the various components shown in the accompanying drawings are not drawn to actual scale.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined or described in one figure, it will not need to be discussed or described in detail in the description of the subsequent figures.

[0039] like Figure 1As shown, this utility model provides a technical solution: a device that can prevent corrosion of the SCR denitrification system of a waste heat boiler, including an ammonia evaporator 1, an ammonia water pipeline 2, a first air pipeline 3, a hot flue gas pipeline 4, a second air pipeline 5, and a nitrogen pipeline 6.

[0040] The outlet of ammonia water pipeline 2 is connected to the inlet of ammonia evaporator 1. Along the direction from the inlet to the outlet of ammonia water pipeline 2, an ammonia water pipeline inlet flow meter 22, an ammonia water pipeline inlet valve 23, and an ammonia injection valve 24 are installed in sequence on ammonia water pipeline 2.

[0041] The ammonia evaporator 1 uses an ammonia pump to deliver ammonia water to the container through the ammonia water pipeline 2. The ammonia water comes into contact with the air in the ammonia evaporator 1 and is atomized, fully reacting with the flue gas to improve the denitrification efficiency. The ammonia water pipeline inlet flow meter 22 can accurately measure the amount of ammonia water injected. The ammonia water pipeline inlet valve 23 has the functions of rapid opening and closing and flow regulation to ensure that the ammonia water source is cut off in time in emergency situations.

[0042] The outlet of the first air pipeline 3 is connected to the ammonia water pipeline 2 between the ammonia injection valve 24 and the outlet of the ammonia water pipeline 2. On the first air pipeline 3, an air inlet main valve 31 and an air valve 32 are installed sequentially from the air inlet to the air outlet.

[0043] Air is pumped through the first air line 3 into the ammonia water line 2, where it comes into full contact with the ammonia water, causing the ammonia water to atomize and thus improving the denitrification efficiency. The air flow in the first air line 3 is controlled by the main air inlet valve 31. In an emergency, the air flow can be cut off by the main air inlet valve 31. Furthermore, the air flow into the ammonia water line 2 can be controlled by the air valve 3.

[0044] The outlet of the hot flue gas pipeline 4 is connected to the inlet of the ammonia evaporator 1. Along the direction from the inlet to the outlet of the hot flue gas pipeline 4, a dilution fan inlet valve 41, a dilution fan 42, and a dilution fan outlet valve 43 are installed in sequence.

[0045] The hot flue gas from the preheating boiler is sequentially sent to the ammonia evaporator 1 through the dilution fan inlet valve 41, the dilution fan 42, and the dilution fan outlet valve 43 to raise the temperature of the ammonia water in the ammonia evaporator 1. The dilution fan 42 sends the hot flue gas to the ammonia evaporator 1 to heat the atomized ammonia water. The purpose is to increase the temperature of the atomized ammonia water and improve the denitrification efficiency.

[0046] The outlet of the second air duct 5 is connected to the hot flue gas duct 4 between the inlet of the hot flue gas duct 4 and the inlet valve 41 of the dilution fan. On the second air duct 5, a cooling fan inlet valve 51, a cooling fan 52 and a cooling fan outlet valve 53 are installed sequentially from the inlet to the outlet of the second air duct 5.

[0047] Air is sequentially sent to the inlet valve 51 of the cooling fan, the cooling fan 52 and the outlet valve 53 of the cooling fan to cool down the hot flue gas entering the ammonia evaporator 1. The cooling fan 52 cools down the flue gas drawn by the dilution fan. The purpose is to prevent the temperature of the ammonia water entering the ammonia evaporator from being too high, which would affect the denitrification efficiency.

[0048] The outlet of nitrogen pipeline 6 connects to ammonia water pipeline 2 between ammonia water pipeline inlet valve 23 and ammonia injection valve 24, enabling connection to the denitrification mechanism. Nitrogen gas can enter from the inlet of nitrogen pipeline and enter the denitrification mechanism from the outlet, displacing any incompletely reacted ammonia water and air remaining in the SCR denitrification system after boiler shutdown, thus extending equipment lifespan. Along nitrogen pipeline 6, from inlet to outlet, a corrosion-resistant primary nitrogen valve 61, a corrosion-resistant nitrogen check valve 62, and a corrosion-resistant secondary nitrogen valve 63 are installed sequentially. The corrosion-resistant nitrogen check valve 62 prevents ammonia water from flowing back into nitrogen pipeline 6.

[0049] Preferably, the ammonia water pipeline 2 between the inlet valve 23 and the outlet of the ammonia water pipeline 2 is provided with at least two ammonia water pipeline branches 21, and each ammonia water pipeline branch 21 is equipped with a corresponding ammonia injection valve 24.

[0050] By setting up at least two ammonia water pipeline branch pipes 21, the efficiency of ammonia water transportation is improved, and by installing an ammonia injection valve on each ammonia water pipeline branch pipe 21, the flow of ammonia water in each ammonia water pipeline branch pipe 21 is precisely controlled.

[0051] Preferably, the first air pipeline 3 between the main air inlet valve 31 and the air outlet of the first air pipeline 3 is provided with a first air pipeline branch pipe 33 corresponding to the number of ammonia water pipeline branch pipes 21, and each first air pipeline branch pipe 33 is equipped with an air valve 32.

[0052] By setting up first air pipeline branch pipes 33 corresponding to the number of ammonia water pipeline branch pipes 21, air is delivered to the ammonia water pipeline branch pipes 21 to atomize the ammonia water, and the air flow is controlled by the air valves 32 on each first air pipeline branch pipe 33.

[0053] Preferably, the second air duct 5 includes an air main 54, a second air duct main 56, and a second air duct branch 55; the air outlet of the air main 54 is connected to the air inlet of the second air duct branch 55 through a first connector 57, and the air inlet of the second air duct main 56 is connected to the air outlet of the second air duct branch 55 through a second connector 58; there are at least two second air duct branch 55s, and a cooling fan inlet valve 51, a cooling fan 52, and a cooling fan outlet valve 53 are sequentially installed on each second air duct branch 55 along the direction from the air inlet to the air outlet.

[0054] In this embodiment, as Figure 1 As shown, there are two second air duct branch pipes 55, and each second air duct branch pipe 55 is equipped with a cooling fan inlet valve 51, a cooling fan 52 and a cooling fan outlet valve 53, thereby improving the efficiency of reducing the temperature of the hot flue gas entering the ammonia evaporator 1, and thus improving the denitrification efficiency.

[0055] Preferably, the hot flue gas pipeline 4 includes a first main flue gas pipeline 44, a branch flue gas pipeline 45, and a second main flue gas pipeline 46.

[0056] The outlet of the first flue gas duct main pipe 44 is connected to the inlet of the flue gas duct branch pipe 45 through the third connector 47. The outlet of the flue gas duct branch pipe 45 is connected to the inlet of the second flue gas duct main pipe 46 through the fourth connector 48. The outlet of the second flue gas duct main pipe 46 is connected to the inlet of the ammonia evaporator 1. The sealing performance of the first flue gas duct 44 is improved through the third connector 47 and the fourth connector 48.

[0057] There are at least two branch pipes 45 of the flue gas duct, and each branch pipe 45 of the flue gas duct is equipped with a dilution fan inlet valve 41, a dilution fan 42 and a dilution fan outlet valve 43 along the direction from the air inlet to the air outlet. The air outlet of the second main air duct 56 is connected to the first main flue gas duct 44 through a fifth connector 49.

[0058] In this embodiment, there are two flue gas duct branch pipes 45, and a dilution fan inlet valve 41, a dilution fan 42, and a dilution fan outlet valve 43 are installed on each flue gas duct branch pipe 45, thereby improving the efficiency of cooling the hot flue gas entering the ammonia evaporator 1 and thus improving the denitrification efficiency of the device.

[0059] More preferably, the device for preventing corrosion of the waste heat boiler SCR denitrification system further includes an ammonia tank, an ammonia pump, an ammonia spraying grid, and an SCR reactor; the ammonia tank is used to store ammonia, the outlet of the ammonia pump is connected to the inlet of the ammonia pipeline, the ammonia pump sends the ammonia in the ammonia tank to the ammonia evaporator and then into the ammonia spraying grid for uniform spraying, and the ammonia flows upward to the SCR reactor to react with the hot flue gas.

[0060] The device for preventing corrosion of the waste heat boiler SCR denitrification system also includes an air pump connected to a first air pipeline, which is used to provide power to the air in the first air pipeline.

[0061] A waste heat boiler includes the device for preventing corrosion of the waste heat boiler SCR denitrification system.

[0062] The specific process of using this device to prevent corrosion in the SCR denitrification system of a waste heat boiler is as follows: During the denitrification stage, close the primary anti-corrosion nitrogen valve 61, the anti-corrosion nitrogen check valve 62, and the secondary anti-corrosion nitrogen valve 63. Open the ammonia water pipeline inlet valve 23, the ammonia injection valve 24, the air inlet main valve 31, and the air valve 32. Air is pumped through the first air pipeline 3 into the ammonia water pipeline 2, and ammonia water is pumped through the ammonia water pipeline 2 to contact the air, spraying it into the ammonia evaporator 1 in a mist form. Open the cooling fan inlet valve, the cooling fan, the cooling fan outlet valve, the dilution fan inlet valve, and the dilution fan outlet valve. The air is cooled and transported to the hot flue gas pipeline 4 through the second air pipeline 5 after the dilution blower outlet valve is opened. The hot flue gas is cooled and heated through the hot flue gas pipeline 4 and then enters the ammonia evaporator 1. It is then sent to the subsequent unit for denitrification treatment through the ammonia evaporator 1. In the corrosion prevention stage, after the denitrification is completed and the unit is shut down, the ammonia water pipeline inlet valve 23 and the air inlet main valve 31 are closed. The corrosion-resistant nitrogen primary valve 61, the corrosion-resistant nitrogen check valve 62 and the corrosion-resistant nitrogen secondary valve 63 are opened to replace the ammonia water and air that have not fully reacted in the SCR denitrification system after the furnace is shut down.

[0063] In summary, this utility model achieves the following technical effects: 1) This utility model optimizes the reaction efficiency of flue gas in the SCR denitrification reactor by setting up multiple ammonia water pipeline branch pipes 21, first air pipeline branch pipes 33, flue gas pipeline branch pipes 45, and second air pipeline branch pipes 56, thereby shortening the residence time of ammonia water and air in the ammonia evaporator. This can prevent corrosion of the SCR denitrification system, prevent ammonia water leakage in the SCR denitrification system, and extend the service life of the equipment. 2) This utility model, through the nitrogen pipeline 6 and the anti-corrosion nitrogen primary valve 61, anti-corrosion nitrogen check valve 62 and anti-corrosion nitrogen secondary valve 63 on the nitrogen pipeline 6, can replace the ammonia water and air that have not fully reacted in the SCR denitrification system after the furnace is shut down, thus extending the service life of the equipment.

[0064] 3) This utility model improves denitrification efficiency and prevents corrosion and leakage of the denitrification system by setting up multiple branch pipes, thereby reducing the emission of harmful gases and having a positive significance for environmental protection and human health.

[0065] 4) This utility model uses a dilution fan 42 to send hot flue gas to an ammonia evaporator 1 to heat the atomized ammonia water, with the aim of increasing the temperature of the atomized ammonia water and improving the denitrification efficiency.

[0066] 5) This utility model uses cooling fan 52 to cool the flue gas drawn by dilution fan 42, in order to prevent the temperature of ammonia water entering the ammonia evaporator from being too high and affecting the denitrification efficiency.

[0067] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for preventing corrosion in a waste heat boiler SCR denitrification system, characterized in that, It includes an ammonia evaporator, ammonia water pipeline, first air pipeline, hot flue gas pipeline, second air pipeline, and nitrogen pipeline; The outlet of the ammonia water pipeline is connected to the inlet of the ammonia evaporator. Along the ammonia water pipeline from the inlet to the outlet, an ammonia water pipeline inlet flow meter, an ammonia water pipeline inlet valve, and an ammonia injection valve are installed in sequence. The outlet of the first air pipeline is connected to the ammonia water pipeline between the ammonia injection valve and the outlet of the ammonia water pipeline. On the first air pipeline, an air inlet main valve and an air valve are installed sequentially from the air inlet to the air outlet. The outlet of the hot flue gas pipeline is connected to the inlet of the ammonia evaporator. Along the hot flue gas pipeline, a dilution fan inlet valve, a dilution fan, and a dilution fan outlet valve are installed in sequence from the inlet to the outlet. The outlet of the second air duct is connected to the hot flue gas duct between the inlet of the hot flue gas duct and the inlet valve of the dilution fan. On the second air duct, a cooling fan inlet valve, a cooling fan and a cooling fan outlet valve are installed sequentially from the inlet to the outlet of the second air duct. The outlet of the nitrogen pipeline is connected to the ammonia water pipeline between the inlet valve of the ammonia water pipeline and the ammonia injection valve. On the nitrogen pipeline, a corrosion-resistant primary nitrogen valve, a corrosion-resistant nitrogen check valve, and a corrosion-resistant secondary nitrogen valve are installed sequentially from the inlet to the outlet.

2. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 1, characterized in that, The ammonia water pipeline between the inlet valve and the outlet of the ammonia water pipeline has at least two branch pipes, and each branch pipe is equipped with a corresponding ammonia injection valve.

3. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 2, characterized in that, The first air pipeline between the main air inlet valve and the outlet of the first air pipeline is provided with first air pipeline branches corresponding to the number of branches of the ammonia water pipeline, and each first air pipeline branch is equipped with an air valve.

4. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 1, characterized in that, The second air duct includes a main air pipe, a second main air duct, and a second branch air duct. The air outlet of the main air pipe is connected to the air inlet of the second air duct branch pipe through the first connector, and the air inlet of the second air duct main pipe is connected to the air outlet of the second air duct branch pipe through the second connector. There are at least two second air duct branches, and on each second air duct branch, a cooling fan inlet valve, a cooling fan, and a cooling fan outlet valve are installed sequentially along the direction from the air inlet to the air outlet.

5. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 4, characterized in that, The hot flue gas pipeline includes a first main flue gas pipeline, a branch flue gas pipeline, and a second main flue gas pipeline. The outlet of the first flue gas duct main is connected to the inlet of the flue gas duct branch pipe via a third connector, the outlet of the flue gas duct branch pipe is connected to the inlet of the second flue gas duct main via a fourth connector, and the outlet of the second flue gas duct main is connected to the inlet of the ammonia evaporator. The flue gas duct has at least two branches, and each of the flue gas duct branches is equipped with a dilution fan inlet valve, a dilution fan, and a dilution fan outlet valve along the direction from the inlet to the outlet. The outlet of the second air duct main is connected to the first flue gas duct main via a fifth connector.

6. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 1, characterized in that, It also includes ammonia tanks, ammonia pumps, ammonia injection grids, and SCR reactors; The ammonia tank is used to store ammonia. The outlet of the ammonia pump is connected to the inlet of the ammonia pipeline. The ammonia pump sends the ammonia in the ammonia tank to the ammonia evaporator and then into the ammonia spraying grid for uniform spraying. The ammonia flows upward to the SCR reactor to react with the hot flue gas.

7. The device for preventing corrosion in a waste heat boiler SCR denitrification system according to claim 1, characterized in that, It also includes an air pump, which is connected to a first air line and is used to power the air in the first air line.

8. A waste heat boiler, characterized in that, Includes the device described in any one of claims 1 to 7 for preventing corrosion in a waste heat boiler SCR denitrification system.

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