Heating furnace flue gas denitration ammonia injection device and process

Abstract

The invention relates to the technical field of petrochemical industry flue gas purification, in particular to a heating furnace flue gas denitration and ammonia injection device and process. The device comprises a reaction device, the front end of an inlet of the reaction device is connected and provided with a mixing device, the front end of an inlet of the mixing device is connected and provided with a preheating device, and the front end of the preheating device is connected and provided with an atomization device. Ammonia water is atomized through the atomization device, the ammonia water is effectively diluted, the supply flow of ammonia is conveniently controlled, the preheating device is used for heating the atomized ammonia water, then the ammonia water is vaporized, ammonia gas is further released, the vaporized ammonia water can be mixed with heating furnace flue gas in the mixing device, the ammonia makes full contact with nitrogen oxide in the heating furnace flue gas, and the nitrogen oxide in the heating furnace flue gas is fully oxidized. And finally, vaporized ammonia water and flue gas mixed gas of the heating furnace enter the reaction device for full reaction, so that the reaction efficiency is high, the residual quantity is small, and the pollution to the atmosphere is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry flue gas purification, and in particular to a heating furnace flue gas denitration and ammonia injection device and process. Background Art

[0002] In recent years, heating furnaces in the petrochemical industry have generally added flue gas denitrification facilities to ensure that nitrogen oxides in the flue gas meet emission standards. The more common denitrification method in the industry is to mix ammonia into the flue gas of the heating furnace. Under the action of the catalyst, the nitrogen oxides in the flue gas react with ammonia, thereby achieving the purpose of removing nitrogen oxides in the flue gas. However, very little ammonia is required in the actual reaction process. With the current control methods, it is difficult to achieve precise and trace control of high-concentration ammonia, resulting in a certain amount of ammonia entering the atmosphere with the flue gas, polluting the environment.

[0003] In the related technology, the ammonia injection regulating valve cannot be put into use, and it is necessary to use a needle valve or a flow limiting orifice plate for on-site manual operation, which is labor-intensive. Since the amount of ammonia injected is very small, it is difficult for the flow meter to accurately indicate the change, and precise and micro-control cannot be performed when the flue gas volume changes. There is a risk of excessive ammonia injection, so that the ammonia that does not participate in the reaction is discharged into the atmosphere with the flue gas, causing environmental pollution. Summary of the invention

[0004] In order to solve the problem that the amount of ammonia injection is difficult to accurately control and to improve the reaction rate of ammonia and nitrogen oxides, the present invention provides a heating furnace flue gas denitration ammonia injection device and process.

[0005] On the one hand, the present invention provides a heating furnace flue gas denitrification ammonia injection device adopts the following technical solution: A device for injecting ammonia into the flue gas of a heating furnace for denitrification comprises a reaction device, wherein nitrogen oxides and ammonia in the flue gas of the heating furnace react in the reaction device, a mixing device is connected and installed at the front end of an inlet of the reaction device, the flue gas of the heating furnace and ammonia are mixed in the mixing device, a preheating device is connected and installed at the front end of an inlet of the mixing device, the ammonia-containing mixture is heated and vaporized in the preheating device, an atomizing device is connected and installed at the front end of the preheating device, and the ammonia-containing mixture is mixed and atomized in the atomizing device.

[0006] The ammonia water is atomized by an atomizing device to effectively dilute the ammonia water and facilitate the control of the ammonia supply flow rate. The preheating device is used to heat the atomized ammonia water, and then vaporize the ammonia water to further release ammonia gas. The vaporized ammonia water can be mixed with the flue gas of the heating furnace in the mixing device, so that the ammonia and the nitrogen oxides in the flue gas of the heating furnace are fully in contact, which is conducive to the next step of mutual reaction. Finally, the vaporized ammonia water and the heating furnace flue gas mixed gas enter the reaction device for full reaction, with high reaction efficiency and small residue, which effectively reduces pollution to the atmosphere.

[0007] Furthermore, the atomizing device includes an atomizing nozzle, which is respectively connected to an air inlet and an ammonia water inlet, the ammonia water inlet injects ammonia water into the atomizing nozzle, the air inlet sprays high-pressure air into the atomizing nozzle and drives the ammonia water to form misted ammonia water, and one end of the atomizing nozzle sprays toward the interior of the preheating device and sprays air and misted ammonia water into the interior of the preheating device.

[0008] The air inlet controls the entry of compressed air, and uses the negative pressure of high-pressure air to quickly atomize the ammonia water. The micropores of the atomizing nozzle further increase the diameter of the ammonia water atomized droplet particles, making it easier to heat and vaporize them later.

[0009] Furthermore, an air regulating valve is installed at the connection channel between the air inlet and the atomizing nozzle, and the air regulating valve adjusts the air inlet intake pressure, intake speed and intake flow rate by control. An ammonia regulating valve is installed at the connection channel between the ammonia inlet and the atomizing nozzle, and the ammonia regulating valve adjusts the ammonia inlet liquid supply speed and liquid supply amount by control.

[0010] The air regulating valve can be used to adjust the flow rate and flow velocity of compressed air, and further adjust the atomization effect and efficiency. The ammonia regulating valve can be used to adjust the ammonia supply flow rate, and cooperate with the air regulating valve to adjust the ammonia supply according to the flue gas discharge of the heating furnace, thereby reducing the problem of insufficient reaction.

[0011] Furthermore, a heating pipe is provided inside the insulation shell of the preheating device, and high-temperature steam is continuously passed into the heating pipe. The heating pipe conducts the heat of the high-temperature steam into the insulation shell of the preheating device through the pipe wall and heats the misted ammonia water and air sprayed into the insulation shell of the preheating device by the atomizing device.

[0012] The heating tube heats the internal atomized ammonia water and air through high-temperature steam, and the heating efficiency is high and stable.

[0013] Furthermore, the two ends of the heating tube are respectively arranged as a steam inlet and a condensed water outlet, the steam inlet injects high-temperature steam into the heating tube, and the condensed water outlet collects and leads out the condensed water after heat exchange in the heating tube. The heating tube is spirally shaped and spirally arranged along the direction of mist ammonia and air injection, the steam inlet is arranged at the far end of the direction of mist ammonia and air injection, and the corresponding condensed water outlet is arranged at the proximal end of the direction of mist ammonia and air injection.

[0014] The spiral shape of the heating tube is conducive to fully heating and vaporizing the mist ammonia water and air. The arrangement of the steam inlet and the condensed water outlet gradually increases the temperature when heating the mist ammonia water and air, which is conducive to improving the uniformity and adequacy of heating.

[0015] Furthermore, a flow-restricted stirring device is arranged in the closed shell of the mixing device, the mixing device is connected to one end of the outlet of the preheating device through an ammonia mixed steam inlet and receives misted ammonia water and air from the preheating device through the ammonia mixed steam inlet, the mixing device is connected to the exhaust pipe of the heating furnace through the flue gas exhaust inlet and receives the flue gas exhaust from the heating furnace through the flue gas exhaust inlet, the ammonia mixed steam inlet and the flue gas exhaust inlet both spray toward the flow-restricted stirring device in the mixing device, the mixing device is connected to the reaction device through the mixed gas outlet and draws out the misted ammonia water and air mixed with the flue gas exhaust of the heating furnace through the flow-restricted stirring device and transports them to the reaction device.

[0016] The misted ammonia water, air and flue gas from the heating furnace are first fully and evenly mixed in the mixing device, so that the nitrogen oxides and ammonia are fully integrated, which is beneficial to improving the reaction efficiency.

[0017] Furthermore, catalyst beds and rectifying layers are installed in an interval arrangement in the sealed cylinder of the reaction device. The catalyst beds and rectifying layers respectively closely match the cross-section of the sealed cylinder of the reaction device and are in contact with all the misted ammonia water, air and flue gas exhaust from the heating furnace passing through the reaction device. The misted ammonia water, air and flue gas exhaust from the heating furnace pass through the catalyst bed and the rectifying layer and are discharged from the sealed cylinder of the reaction device through the denitrification flue gas outlet arranged at the end of the reaction device.

[0018] The rectifying layer can slow down the passage speed of the mixed gas, which is beneficial to the full reaction of the mixed gas on the catalyst bed, reduce the residue, attach the catalyst to the catalyst bed, increase the reaction rate of nitrogen oxides and ammonia, and is beneficial to the continuous purification.

[0019] Furthermore, the catalyst bed is arranged in at least two layers in the sealed cylinder of the reaction device, and the rectifying layer is arranged in at least one layer at the beginning and the end of the sealed cylinder of the reaction device, and the catalyst bed is arranged in the middle of the rectifying layer at the beginning and the end of the sealed cylinder of the reaction device.

[0020] The catalyst bed is arranged with at least two layers at intervals, and the terminal rectifying layer is beneficial to maintaining the residence time of the mixed gas in the reaction device, further improving the completeness of the reaction and further reducing the residue.

[0021] On the other hand, the present invention provides a heating furnace flue gas denitrification ammonia injection process adopts the following technical solution: A heating furnace flue gas denitrification and ammonia injection process includes the following process flow: Ammonia water is regulated and controlled to enter the atomizing nozzle through the ammonia water regulating valve, and then high-pressure air is regulated and controlled to enter the atomizing nozzle through the air regulating valve. The ammonia water in the atomizing nozzle is atomized under the action of the high-pressure air; The atomizing nozzle sprays the atomized ammonia water and air mixture into the preheating device for heating to form high-temperature steam of ammonia water and air mixture; The high-temperature steam mixed with ammonia water and air heated by the preheating device enters the mixing device and is fully mixed with the flue gas and tail gas from the heating furnace; The fully mixed gas of ammonia vapor, air and flue gas is transported to the reaction device for reaction to consume nitrogen oxides in the flue gas from the heating furnace until the nitrogen oxide content in the mixed gas meets the emission standards and is discharged from the reaction device.

[0022] Using ammonia water vaporization to supply ammonia, compared with direct ammonia gas supply, at the same flow rate, the ammonia content is reduced, the flow rate of ammonia water injection is increased, the flow meter can accurately indicate, the regulating valve can be adjusted normally, and the labor intensity is reduced. In addition, this process can achieve precise and trace control of the amount of ammonia used in the denitrification process of the heating furnace flue gas, avoiding environmental pollution caused by the escape of ammonia in the denitrification flue gas of the heating furnace.

[0023] Furthermore, the mixed gas reaction step in the reaction device specifically includes: The mixed gas entering the reaction device first passes through the initial end rectifying layer for rectification; The rectified mixed gas is uniformly transported to contact the catalyst bed. Under the action of the catalyst on the catalyst bed, the nitrogen oxides react with ammonia to achieve the purpose of consuming the nitrogen oxides. The mixed gas after the reaction is rectified again by the rectifying layer at the end and then discharged evenly and slowly from the reaction device.

[0024] The rectifying layer and the catalyst bed effectively improve the efficiency of consuming nitrogen oxides.

[0025] In summary, the present invention has the following beneficial technical effects: 1. Ammonia water is atomized by an atomizing device to effectively dilute the ammonia water and facilitate the control of the ammonia supply flow rate. The preheating device is used to heat the atomized ammonia water, and then vaporize the ammonia water to further release ammonia gas. The vaporized ammonia water can be mixed with the flue gas of the heating furnace in the mixing device, so that the ammonia and the nitrogen oxides in the flue gas of the heating furnace are fully in contact, which is conducive to the next step of mutual reaction. The final vaporized ammonia water and the heating furnace flue gas mixed gas enter the reaction device for full reaction, with high reaction efficiency and small residue, effectively reducing pollution to the atmosphere.

[0026] 2. The air inlet controls the entry of compressed air, and the negative pressure of high-pressure air is used to quickly atomize the ammonia water. The micropores of the atomizing nozzle further increase the diameter of the ammonia water atomized droplets, which is convenient for subsequent heating and vaporization. The air regulating valve can be used to adjust the flow and flow rate of compressed air, and further adjust the atomization effect and efficiency. The ammonia water regulating valve can be used to adjust the ammonia water supply flow rate, and cooperate with the air regulating valve to adjust the ammonia supply according to the exhaust volume of the heating furnace flue gas, thereby reducing the problem of insufficient reaction.

[0027] 3. The heating tube heats the internal atomized ammonia water and air through high-temperature steam, with high and stable heating efficiency. The spiral shape of the heating tube is conducive to fully heating and vaporizing the misted ammonia water and air. The steam inlet and condensed water outlet are set to gradually increase the temperature when heating the misted ammonia water and air, which is conducive to improving the uniformity and adequacy of heating.

[0028] 4. The mist ammonia water, air and flue gas exhaust of the heating furnace are first fully mixed in the mixing device to make the nitrogen oxides and ammonia fully integrated, which is beneficial to improve the reaction efficiency. The rectifying layer can slow down the passage speed of the mixed gas, which is beneficial to the full reaction of the mixed gas on the catalyst bed and reduce the residue. The catalyst is attached to the catalyst bed, which increases the reaction rate of nitrogen oxides and ammonia and is beneficial to the continuous purification.

[0029] 5. The catalyst bed is set at least two layers apart, and the terminal rectifying layer is beneficial to maintain the residence time of the mixed gas in the reaction device, further improve the completeness of the reaction, and further reduce the residue.

[0030] 6. Ammonia is supplied by vaporizing ammonia water. Compared with direct ammonia supply, the ammonia content is reduced at the same flow rate, the flow rate of ammonia water injection is increased, the flow meter can accurately indicate, the regulating valve can be adjusted normally, and the labor intensity is reduced. In addition, this process can achieve precise and trace control of the amount of ammonia used in the denitrification process of the heating furnace flue gas, avoiding environmental pollution caused by ammonia escape from the denitrification flue gas of the heating furnace. The rectifier layer and catalyst bed layer effectively improve the sufficiency and efficiency of consuming nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the connection of the process equipment of the present invention.

[0032] Description of reference numerals: 1. Atomizing device, 11. Air inlet, 111. Air regulating valve, 12. Ammonia water inlet, 121. Ammonia water regulating valve, 13. Atomizing nozzle, 2. Preheating device, 21. Heating tube, 211. Steam inlet, 212. Condensate water outlet, 3. Mixing device, 31. Ammonia mixed steam inlet, 32. Flue gas and exhaust gas inlet, 33. Mixed gas outlet, 4. Reaction device, 41. Catalyst bed, 42. Rectification layer, 43. Denitrification flue gas outlet. DETAILED DESCRIPTION

[0033] The following will be combined with the attached Figure 1 , the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention. Example

[0035] The embodiment of the present invention discloses a heating furnace flue gas denitrification ammonia injection device, referring to Figure 1 , comprising a reaction device 4, in which nitrogen oxides and ammonia in the flue gas of the heating furnace react; The front end of the inlet of the reaction device 4 is connected and installed with a mixing device 3, and the heating furnace flue gas and ammonia are mixed in the mixing device 3; The front end of the inlet of the mixing device 3 is connected and installed with a preheating device 2, and the ammonia-containing mixture is heated and vaporized in the preheating device 2; The front end of the preheating device 2 is connected to and installed with an atomizing device 1, and the ammonia-containing mixture is mixed and atomized in the atomizing device 1.

[0036] When in use, ammonia water and compressed air are poured into the atomizing device 1, and the compressed air forms high-pressure gas, forming negative pressure in the atomizing device 1, and the ammonia water is quickly atomized into tiny suspended droplets, and then enters the preheating device 2 for high-temperature heating, and then the atomized ammonia water is quickly vaporized, and the vaporized ammonia water is pre-mixed with the flue gas of the heating furnace in the mixing device 3, and then the mixed gas is transported to the reaction device 4 for reaction, and NOx and NH3 react in the reaction device 4, effectively reducing the content of NOx and NH3. Example

[0037] On the basis of Example 1, add: Reference Figure 1 The atomizing device 1 includes an atomizing nozzle 13, which is respectively connected to an air inlet 11 and an ammonia water inlet 12. The ammonia water inlet 12 injects ammonia water into the atomizing nozzle 13. The air inlet 11 sprays high-pressure air into the atomizing nozzle 13 and drives the ammonia water to form a misted ammonia water. One end of the atomizing nozzle 13 sprays toward the inside of the preheating device 2 and sprays air and ammonia water into the inside of the preheating device 2.

[0038] Use 5.5% ammonia solution.

[0039] Reference Figure 1 An air regulating valve 111 is installed at the connection channel between the air inlet 11 and the atomizing nozzle 13. The air regulating valve 111 controls and adjusts the air intake pressure, air intake speed and air intake flow rate of the air inlet 11. An ammonia regulating valve 121 is installed at the connection channel between the ammonia inlet 12 and the atomizing nozzle 13. The ammonia regulating valve 121 controls and adjusts the liquid supply speed and liquid supply amount of the ammonia inlet 12.

[0040] The conveying speed is controlled by rotating the air regulating valve 111 and the ammonia regulating valve 121. It is necessary to detect the nitrogen oxide content in the flue gas of the heating furnace in advance and test the optimal conveying speed of ammonia and compressed air. During the purification process, the nitrogen oxide content and ammonia content of the exhausted flue gas are continuously monitored to see if they meet the standards.

[0041] Reference Figure 1 A heating pipe 21 is arranged inside the insulation shell of the preheating device 2, and high-temperature steam is continuously passed into the heating pipe 21. The heating pipe 21 conducts the heat of the high-temperature steam into the insulation shell of the preheating device 2 through the pipe wall and heats the misted ammonia water and air sprayed into the insulation shell of the preheating device 2 by the atomizing device 1.

[0042] The atomized ammonia water is heated to above 150° C. by the preheating device 2 .

[0043] Reference Figure 1 The two ends of the heating tube 21 are respectively arranged with a steam inlet 211 and a condensed water outlet 212. The steam inlet 211 injects high-temperature steam into the heating tube 21, and the condensed water outlet 212 collects and leads out the condensed water after heat exchange in the heating tube 21. The heating tube 21 is spirally shaped and spirally arranged along the direction of mist ammonia and air injection. The steam inlet 211 is arranged at the far end of the direction of mist ammonia and air injection, and the condensed water outlet 212 is arranged at the near end of the direction of mist ammonia and air injection.

[0044] The evaporator is heated by 1.0MPa steam, and the condensed water produced after condensation is drained into the condensate pipe network after being drained by the steam trap.

[0045] Reference Figure 1 A flow-blocking stirring device is arranged in the closed shell of the mixing device 3. The mixing device 3 is connected to one end of the outlet of the preheating device 2 through an ammonia mixed steam inlet 31 and receives the misted ammonia water and air from the preheating device 2 through the ammonia mixed steam inlet 31. The mixing device 3 is connected to the exhaust pipe of the heating furnace through the flue gas exhaust inlet 32 ​​and receives the flue gas exhaust from the heating furnace through the flue gas exhaust inlet 32. The ammonia mixed steam inlet 31 and the flue gas exhaust inlet 32 ​​both spray toward the flow-blocking stirring device in the mixing device 3. The mixing device 3 is connected to the reaction device 4 through the mixed gas outlet 33 and draws out the misted ammonia water and air mixed by the flow-blocking stirring device and the flue gas exhaust of the heating furnace and transports them to the reaction device 4.

[0046] Reference Figure 1 The sealed cylinder of the reaction device 4 is provided with catalyst beds 41 and rectifying layers 42 arranged at intervals. The catalyst beds 41 and rectifying layers 42 respectively closely match the cross-section of the sealed cylinder of the reaction device 4 and are in contact with all the misted ammonia water, air and flue gas exhaust of the heating furnace passing through the reaction device 4. The misted ammonia water, air and flue gas exhaust of the heating furnace pass through the catalyst beds 41 and rectifying layers 42 and are discharged from the sealed cylinder of the reaction device 4 through the denitrification flue gas outlet 43 arranged at the end of the reaction device 4.

[0047] Reference Figure 1 The catalyst bed 41 is arranged in at least two layers in the sealed cylinder of the reaction device 4, and the rectifying layer 42 is arranged in at least one layer at the beginning and the end of the sealed cylinder of the reaction device 4, and the catalyst bed 41 is arranged in the middle of the rectifying layer 42 at the beginning and the end of the sealed cylinder of the reaction device 4. Example

[0048] The embodiment of the present invention discloses a heating furnace flue gas denitrification ammonia injection process, referring to Figure 1 , including the following process: Ammonia water is regulated and controlled to enter the atomizing nozzle 13 through the ammonia water regulating valve 121, and then high-pressure air is regulated and controlled to enter the atomizing nozzle 13 through the air regulating valve 111. The ammonia water in the atomizing nozzle 13 is atomized under the action of the high-pressure air; The atomizing nozzle 13 sprays the atomized ammonia water and air mixture into the preheating device 2 for heating to form high-temperature steam of ammonia water and air mixture; The high-temperature steam mixed with ammonia water and air heated by the preheating device 2 enters the mixing device 3 and is fully mixed with the flue gas and tail gas from the heating furnace; The fully mixed gas of ammonia vapor, air and flue gas is transported to the reaction device 4 for reaction to consume nitrogen oxides in the flue gas from the heating furnace until the nitrogen oxide content in the mixed gas meets the emission standards and is discharged from the reaction device 4.

[0049] Reference Figure 1 The mixed gas reaction step in the reaction device 4 specifically includes: The mixed gas entering the reaction device 4 first passes through the initial end rectifying layer 42 for rectification; The rectified mixed gas is uniformly transported to contact the catalyst bed 41. Under the action of the catalyst on the catalyst bed 41, the nitrogen oxides react with ammonia to achieve the purpose of consuming the nitrogen oxides. The mixed gas after the reaction is rectified again by the tail end rectifying layer 42 and then discharged from the reaction device 4 evenly and slowly.

Claims

1. A heating furnace flue gas denitrification ammonia injection device, characterized in that: It comprises a reaction device (4), in which nitrogen oxides and ammonia in the flue gas of the heating furnace react; The front end of the inlet of the reaction device (4) is connected to and installed with a mixing device (3), and the heating furnace flue gas and ammonia are mixed in the mixing device (3); The front end of the inlet of the mixing device (3) is connected to and installed with a preheating device (2), and the ammonia-containing mixture is heated and vaporized in the preheating device (2); The front end of the preheating device (2) is connected to and installed with an atomizing device (1), and the ammonia-containing mixture is mixed and atomized in the atomizing device (1).

2. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 1, characterized in that: The atomizing device (1) comprises an atomizing nozzle (13), the atomizing nozzle (13) being respectively connected to an air inlet (11) and an ammonia water inlet (12), the ammonia water inlet (12) injecting ammonia water into the atomizing nozzle (13), the air inlet (11) spraying high-pressure air into the atomizing nozzle (13) and driving the ammonia water to form a mist of ammonia water, and the atomizing nozzle (13) spraying one end toward the interior of the preheating device (2) and spraying air and ammonia water mist into the interior of the preheating device (2).

3. A heating furnace flue gas denitrification ammonia injection device according to claim 2, characterized in that: An air regulating valve (111) is installed at the connection passage between the air inlet (11) and the atomizing nozzle (13), and the air regulating valve (111) regulates the air intake pressure, air intake speed and air intake flow rate of the air inlet (11) by control. An ammonia regulating valve (121) is installed at the connection passage between the ammonia inlet (12) and the atomizing nozzle (13), and the ammonia regulating valve (121) regulates the liquid supply speed and liquid supply amount of the ammonia inlet (12) by control.

4. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 1, characterized in that: A heating pipe (21) is arranged inside the heat-insulating shell of the preheating device (2), and high-temperature steam is continuously passed into the heating pipe (21). The heating pipe (21) conducts the heat of the high-temperature steam into the heat-insulating shell of the preheating device (2) through the pipe wall and heats the misted ammonia water and air sprayed into the heat-insulating shell of the preheating device (2) by the atomizing device (1).

5. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 4, characterized in that: The two ends of the heating tube (21) are respectively provided with a steam inlet (211) and a condensed water outlet (212); the steam inlet (211) injects high-temperature steam into the heating tube (21); the condensed water outlet (212) collects and leads out the condensed water after heat exchange in the heating tube (21); the heating tube (21) is spirally shaped and is spirally arranged along the spray direction of the mist ammonia water and the air; the steam inlet (211) is arranged at the far end in the spray direction of the mist ammonia water and the air; and the condensed water outlet (212) is arranged at the near end in the spray direction of the mist ammonia water and the air.

6. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 1, characterized in that: A flow-blocking stirring device is arranged in the closed shell of the mixing device (3). The mixing device (3) is connected to one end of the outlet of the preheating device (2) through the ammonia mixed steam inlet (31) and receives misted ammonia water and air from the preheating device (2) through the ammonia mixed steam inlet (31). The mixing device (3) is connected to the exhaust gas discharge pipe of the heating furnace through the flue gas exhaust inlet (32) and receives flue gas exhaust from the heating furnace through the flue gas exhaust inlet (32). Both the ammonia mixed steam inlet (31) and the flue gas exhaust inlet (32) spray toward the flow-blocking stirring device in the mixing device (3). The mixing device (3) is connected to the reaction device (4) through the mixed gas outlet (33) and draws out the misted ammonia water and air mixed with the flue gas exhaust of the heating furnace through the flow-blocking stirring device and transports them to the reaction device (4).

7. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 1, characterized in that: Catalyst beds (41) and rectifying layers (42) are installed in a sealed cylinder of the reaction device (4) at intervals. The catalyst beds (41) and rectifying layers (42) are respectively closely matched with the cross-section of the sealed cylinder of the reaction device (4) and are in contact with all mist ammonia water, air and flue gas exhaust from the heating furnace that pass through the reaction device (4). The mist ammonia water, air and flue gas exhaust from the heating furnace pass through the catalyst beds (41) and rectifying layers (42) and are discharged from the sealed cylinder of the reaction device (4) through a denitrification flue gas outlet (43) provided at the end of the reaction device (4).

8. The device for injecting ammonia into the flue gas of a heating furnace for denitrification according to claim 7, characterized in that: The catalyst bed (41) is provided at least two layers at intervals in the sealed cylinder of the reaction device (4), the rectifying layer (42) is provided at least one layer each at the beginning and the end of the sealed cylinder of the reaction device (4), and the catalyst bed (41) is provided between the rectifying layers (42) at the beginning and the end of the sealed cylinder of the reaction device (4).

9. A heating furnace flue gas denitrification ammonia injection process, characterized in that: Including the following process: Ammonia water is regulated and controlled to enter the atomizing nozzle (13) through the ammonia water regulating valve (121), and high-pressure air is regulated and controlled to enter the atomizing nozzle (13) through the air regulating valve (111), and the ammonia water in the atomizing nozzle (13) is atomized under the action of the high-pressure air; The atomizing nozzle (13) sprays the atomized ammonia water and air mixture into the preheating device (2) for heating to form high-temperature steam of the ammonia water and air mixture; The high-temperature steam mixed with the ammonia water and air heated by the preheating device (2) enters the mixing device (3) and is fully mixed with the flue gas and tail gas from the heating furnace; The fully mixed gas of ammonia vapor, air and flue gas is transported to the reaction device (4) for reaction to consume nitrogen oxides in the flue gas from the heating furnace until the nitrogen oxide content in the mixed gas meets the emission standard and then is discharged from the reaction device (4).

10. A heating furnace flue gas denitrification ammonia injection process according to claim 9, characterized in that: The mixed gas reaction step in the reaction device (4) specifically includes: The mixed gas entering the reaction device (4) first passes through the initial end rectifying layer (42) for rectification; The rectified mixed gas is uniformly transported to contact the catalyst bed (41), and under the action of the catalyst on the catalyst bed (41), the nitrogen oxides react with ammonia to achieve the purpose of consuming the nitrogen oxides; The mixed gas after the reaction is rectified again through the tail end rectifying layer (42) and then discharged evenly and slowly from the reaction device (4).

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