Ammonia injection mixing equipment for flue gas denitration

Abstract

The application provides a kind of ammonia injection mixing equipment for flue gas denitration, comprising: main pipeline, with main channel for flue gas flow through;Inner ring pipeline is coaxially arranged in main channel, inner ring pipeline includes first pipe section, reducing pipe section and second pipe section in turn along the direction of flue gas flow, the inner diameter of first pipe section is smaller than second pipe section, the interval distance between the outer surface of first pipe section and the inner wall of main channel is greater than the interval distance between the outer surface of second pipe section and the inner wall of main channel;Atomizing nozzle, atomizing nozzle is arranged at the opening of second pipe section away from reducing pipe section side, atomizing nozzle is connected to reducing agent pipeline.According to the technical scheme of the application, the problem of uneven distribution of reactants and easy adhesion of reducing agent to the inner wall can be improved, thereby improving the denitration effect.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment technology, and in particular to an ammonia injection mixing device for flue gas denitrification. Background Technology

[0002] Common technologies for flue gas denitrification in boilers include low-NOx combustion, selective non-catalytic reduction (SNCR), and selective catalytic reduction (SCR). Among these, low-NOx combustion and SNCR can only be used as pretreatment methods, while SCR is the key technology for achieving ultra-low NOx emissions from flue gas. Common reducing agents used in SNCR and SCR include ammonia, ammonia water, and urea.

[0003] SNCR technology requires a high-temperature environment of 850–1100℃ and typically occurs within the furnace. When ammonia or urea solution is sprayed into the furnace in atomized form, the ammonia or urea rapidly decomposes and reacts with NOx in the flue gas, converting it into N2 and H2O. However, due to the complex combustion and flow field within the furnace, it is difficult to achieve uniform mixing of the flue gas and the reducing agent when directly injected, resulting in a denitrification efficiency of only about 30%. Excessive use of the reducing agent can cause severe ammonia escape and affect the normal operation of subsequent SCR processes.

[0004] For denitrification of exhaust gases from heavy-duty diesel vehicles or marine engines, SCR (Selective Catalytic Reduction) technology is primarily used to ensure compliance with emission standards. Urea aqueous solution is a commonly used reducing agent. In practical applications, the urea aqueous solution spray in the SCR system is constrained by the exhaust pipe, causing the sprayed solution to impact the wall and form a liquid film. The evaporation of this liquid film absorbs heat, lowering the wall temperature and exacerbating the incomplete decomposition of the urea aqueous solution, resulting in urea crystals and other deposits such as biuret and cyanuric acid. This reduces the utilization rate of the urea aqueous solution and affects the denitrification efficiency. Summary of the Invention

[0005] This invention provides an ammonia injection mixing device for flue gas denitrification, which solves the defects in the prior art that lead to unsatisfactory flue gas denitrification effect due to uneven distribution of reactants and easy adhesion of reducing agent to the inner wall. It improves the problem of uneven distribution of reactants and easy adhesion of reducing agent to the inner wall, thereby improving the denitrification effect.

[0006] This invention provides an ammonia injection mixing device for flue gas denitrification, comprising: a main pipeline having a main channel for flue gas flow; an inner ring pipeline coaxially disposed within the main channel, the inner ring pipeline sequentially comprising a first pipe section, a reducing pipe section, and a second pipe section along the flue gas flow direction, wherein the inner diameter of the first pipe section is smaller than that of the second pipe section, and the distance between the outer surface of the first pipe section and the inner wall of the main channel is greater than the distance between the outer surface of the second pipe section and the inner wall of the main channel; and an atomizing nozzle disposed at an opening on the side of the second pipe section away from the reducing pipe section, the atomizing nozzle being connected to a reducing agent pipeline.

[0007] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein a guide cap is provided downstream of the inner ring pipe in the flue gas flow direction; one side of the guide cap is convex and the other side is concave; the convex side of the guide cap faces the inner ring pipe, and the concave side of the guide cap faces away from the inner ring pipe.

[0008] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein a reverse flow guiding mechanism is provided downstream of the flow guide cap; the reverse flow guiding mechanism includes a mixing channel coaxially arranged with the flow guide cap, and an annular flow guiding groove with its opening facing the edge of the flow guide cap is formed between the mixing channel and the inner wall of the main channel.

[0009] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein the cross-sectional shape of the annular guide channel is arc-shaped, the outer edge of the annular guide channel is connected to the inner wall of the main channel, and the inner edge of the annular guide channel is located within the projection range of the concave side of the guide cap; or, the reverse guide mechanism includes an outer peripheral guide plate and an inner peripheral guide plate, and the annular guide channel is formed between the outer peripheral guide plate and the inner peripheral guide plate.

[0010] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein a support plate is connected between the outer peripheral guide plate and the inner peripheral guide plate, and the support plate forms the bottom of the annular guide groove; the outer peripheral guide plate is located outside the projection range of the concave side of the guide cap, and the inner peripheral guide plate is located within the projection range of the concave side of the guide cap.

[0011] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein a diffusion pipe section is provided between the end of the mixing channel away from the guide cap and the inner wall of the main channel; the inner diameter of the diffusion pipe section gradually increases in the flue gas flow direction.

[0012] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein a dispersion plate is provided in the diffuser section; the area of ​​the dispersion plate is smaller than the cross-sectional area of ​​the mixing channel; the dispersion plate, the mixing channel and the guide cap are coaxially arranged.

[0013] According to the present invention, an ammonia mixing device for flue gas denitrification is provided, wherein the atomizing nozzle is further connected to a compressed air or steam pipeline.

[0014] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein the injection direction of the atomizing nozzle is in the same direction as the flue gas flow direction; or, the injection direction of the atomizing nozzle is opposite to the flue gas flow direction; or, the number of atomizing nozzles is multiple, wherein a portion of the atomizing nozzles are injected in the same direction as the flue gas flow direction, and another portion of the atomizing nozzles are injected in the opposite direction to the flue gas flow direction.

[0015] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein the cross-sectional shape of the main pipe and the inner ring pipe is square or circular.

[0016] The ammonia injection mixing device for flue gas denitrification provided by this invention achieves flue gas denitrification by reacting a reducing agent sprayed from atomizing nozzles with the flue gas within the main channel. The main feature of this device is the use of a variable-diameter pipe section and an inner ring pipe to achieve flue gas mixing and uniform distribution of the reducing agent. In the inner ring pipe, as the flue gas flows from the first pipe section to the second pipe section, the change in pipe diameter causes a decrease in air pressure and a slowdown in flow velocity. Simultaneously, because the distance between the outer surface of the first pipe section and the inner wall of the main channel is greater than the distance between the outer surface of the second pipe section and the inner wall of the main channel, the flue gas flowing in the gap between the inner ring pipe and the main channel experiences increased air pressure and a faster flow velocity after passing the outer side of the variable-diameter pipe section. When the reducing agent is sprayed from the atomizing nozzles, the high-speed flue gas near the edge of the main channel can carry the atomized reducing agent along, preventing the reducing agent from adhering to the pipe wall. Furthermore, due to the pressure difference between the flue gas flowing on the inner and outer sides of the inner ring pipe, radial mixing occurs within the main channel after the flue gas passes through the inner ring pipe. This improves the mixing efficiency of the reducing agent and flue gas, resulting in a more uniform mixture. Therefore, this ammonia injection mixing equipment for flue gas denitrification can improve the uneven distribution of reactants and the tendency of the reducing agent to adhere to the inner wall, thereby enhancing the denitrification effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is one of the internal structural schematic diagrams of the ammonia injection mixing device for flue gas denitrification provided by the present invention;

[0019] Figure 2 This is the second schematic diagram of the internal structure of the ammonia injection mixing device for flue gas denitrification provided by the present invention;

[0020] Figure 3 This is a top view of the ammonia injection mixing device for flue gas denitrification provided by the present invention.

[0021] Figure 4 This is a schematic diagram showing the partial structural dimensions of the ammonia injection mixing device for flue gas denitrification provided by the present invention.

[0022] Figure 5 This is a schematic diagram of the usage status of the ammonia injection mixing device for flue gas denitrification provided by the present invention;

[0023] Figure label:

[0024] 10. Main pipe; 21. First pipe section; 22. Reducing pipe section; 23. Second pipe section; 30. Atomizing nozzle; 31. Reducing agent pipeline; 32. Compressed air or steam pipeline; 41. Guide cap; 42. Mixing channel; 43. Annular guide groove; 44. Outer peripheral guide plate; 45. Inner peripheral guide plate; 46. Support plate; 47. Diffusion pipe section; 48. Dispersion plate. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention 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 the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that in the description of the present invention, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] The following is combined with Figures 1-5 This invention describes specific embodiments of the ammonia injection mixing device for flue gas denitrification according to the present invention.

[0028] This invention provides an ammonia injection mixing device for flue gas denitrification. It achieves denitrification by reacting a reducing agent sprayed from atomizing nozzles 30 with the flue gas within the main channel. The main feature of this device is the use of a variable-diameter pipe section 22 and an inner ring pipe to achieve both flue gas mixing and uniform distribution of the reducing agent. Figure 1 , Figure 2 and Figure 3 As shown, it includes: a main pipe 10, having a main channel for flue gas circulation; an inner ring pipe, coaxially arranged within the main channel, the inner ring pipe including a first pipe section 21, a reducing pipe section 22 and a second pipe section 23 in sequence along the flue gas circulation direction, the inner diameter of the first pipe section 21 being smaller than that of the second pipe section 23, the distance between the outer surface of the first pipe section 21 and the inner wall of the main channel being greater than the distance between the outer surface of the second pipe section 23 and the inner wall of the main channel; and an atomizing nozzle 30, the atomizing nozzle 30 being disposed at the opening of the second pipe section 23 on the side away from the reducing pipe section 22, and the atomizing nozzle 30 being connected to the reducing agent pipeline 31.

[0029] In the inner ring pipe, as flue gas flows from the first pipe section 21 to the second pipe section 23, the change in pipe diameter causes a decrease in gas pressure and a slowdown in flow velocity. Simultaneously, because the distance between the outer surface of the first pipe section 21 and the inner wall of the main channel is greater than the distance between the outer surface of the second pipe section 23 and the inner wall of the main channel, the flue gas flowing in the gap between the inner ring pipe and the main channel experiences an increase in gas pressure and a faster flow velocity after passing the outside of the variable diameter pipe section 22.

[0030] When the atomizing nozzle 30 sprays the reducing agent, the high-speed flue gas near the edge of the main channel can carry the atomized reducing agent along, preventing it from adhering to the pipe wall. Furthermore, due to the pressure difference between the flue gas flowing on the inner and outer sides of the inner ring pipe, radial mixing occurs within the main channel after the flue gas passes through the inner ring pipe. This improves the mixing efficiency of the reducing agent and flue gas, resulting in a more uniform mixture. Therefore, this ammonia injection mixing device for flue gas denitrification can improve the uneven distribution of reactants and the tendency of the reducing agent to adhere to the inner wall, thereby enhancing the denitrification effect.

[0031] The specific shape of the inner ring pipe can be designed and adjusted according to actual needs. Preferably, the angle between the first pipe section 21 and the reducing pipe section 22 is between 150 degrees and 175 degrees; the angle between the reducing pipe section 22 and the second pipe section 23 is between 150 degrees and 175 degrees. To ensure the flue gas flow capacity of the space between the inner ring pipe and the main channel, the outer diameter of the second pipe section 23 is preferably 0.4 to 0.9 times the inner diameter of the main channel.

[0032] like Figure 1 and Figure 2 As shown, in the flue gas denitrification ammonia injection mixing device provided by the present invention, a guide cap 41 is provided downstream of the inner ring pipe in the flue gas flow direction. One side of the guide cap 41 is convex and the other side is concave; the convex side of the guide cap 41 faces the inner ring pipe, and the concave side of the guide cap 41 faces away from the inner ring pipe.

[0033] When the flue gas flows through the atomizing nozzle 30, the raised side of the guide cap 41 acts as a guide, and the mixture of flue gas and reducing agent gas continues to flow along the edge of the guide cap 41. During the process of the mixed gas passing through the guide cap 41, a negative pressure is formed on the concave side of the guide cap 41, which in turn promotes further radial mixing of the mixed gas after passing through the guide cap 41, accelerating the reaction between the flue gas and the reducing agent.

[0034] The raised side of the guide cap 41 is preferably a smooth arc shape. This shape helps to reduce flow resistance, make the mixed gas flow more smoothly, and prevent dust in the flue gas from depositing on its surface, thereby keeping the equipment clean and efficient.

[0035] Furthermore, in the ammonia injection mixing device for flue gas denitrification provided by the present invention, a reverse flow guiding mechanism is provided downstream of the flow guide cap 41. For example... Figure 1 and Figure 2 As shown, the reverse flow guiding mechanism includes a mixing channel 42 coaxially arranged with the flow guide cap 41, and an annular flow guide groove 43 with its opening facing the edge of the flow guide cap 41 is formed between the mixing channel 42 and the inner wall of the main channel.

[0036] According to this reverse flow guiding mechanism, the annular flow guide groove 43 can guide the mixed gas flowing along the pipe wall to the concave side of the flow guide cap 41, thereby further promoting the mixing of the mixed gas on the concave side of the flow guide cap 41, accelerating the reaction rate, and improving the reaction efficiency. The concave side of the flow guide cap 41 is preferably an arc-shaped concave surface. The mixed gas guided by the annular flow guide groove 43 flows along the arc-shaped concave surface to the center of the concave side, and after mixing, continues to move in the flue gas flow direction through the mixing channel 42.

[0037] According to the aforementioned ammonia injection mixing equipment for flue gas denitrification, the cross-sectional shape of the annular guide channel 43 can be arc-shaped. The outer edge of the annular guide channel 43 is connected to the inner wall of the main channel, and the inner edge of the annular guide channel 43 is located within the projection range of the concave side of the guide cap 41. The arc-shaped cross-sectional shape of the annular guide channel 43 effectively guides the mixed gas flowing along the pipe wall to the concave side of the guide cap 41, thereby better guiding the mixed gas towards the center.

[0038] Alternatively, the aforementioned reverse flow guiding mechanism may include an outer peripheral guide plate 44 and an inner peripheral guide plate 45, with an annular flow guide groove 43 formed between the outer peripheral guide plate 44 and the inner peripheral guide plate 45. The outer peripheral guide plate 44 is connected to the inner wall of the main channel, and the end of the inner peripheral guide plate 45 extends into the projection range of the recessed side of the guide cap 41. After the mixed gas passes through the guide cap 41, it is first guided by the outer peripheral guide plate 44, causing the mixed gas to flow towards the inner peripheral guide plate 45. Then, the mixed gas is guided by the inner peripheral guide plate 45, causing it to flow towards the recessed side of the guide cap 41.

[0039] Furthermore, to better guide the mixed gas, an arc-shaped chamfer can be provided between the outer peripheral guide plate 44 and the inner peripheral guide plate 45; or, according to the ammonia injection mixing device for flue gas denitrification provided by the present invention, a support plate 46 is connected between the outer peripheral guide plate 44 and the inner peripheral guide plate 45. Figure 1 and Figure 2 As shown, the support plate 46 forms the bottom of the annular guide groove 43; the outer peripheral guide plate 44 is located outside the projection range of the concave side of the guide cap 41, and the inner peripheral guide plate 45 is located within the projection range of the concave side of the guide cap 41. Through the transition of the support plate 46, the flow guiding effect of the reverse flow guiding mechanism on the mixed gas can be made smoother. After the mixed gas passes through the guide cap 41, it is first guided by the outer peripheral guide plate 44, causing the mixed gas to flow towards the support plate 46. Then, the mixed gas moves along the support plate 46 to the inner peripheral guide plate 45, and is further guided by the inner peripheral guide plate 45, causing the mixed gas to flow towards the concave side of the guide cap 41. Preferably, the angle between the inner peripheral guide plate 45 and the mixing channel 42 is 10 degrees to 45 degrees, and the angle between the outer peripheral guide plate 44 and the inner wall of the main channel is 20 degrees to 70 degrees.

[0040] like Figure 1 , Figure 2 As shown, in an ammonia injection mixing device for flue gas denitrification provided by the present invention, a diffuser section 47 is provided between the end of the mixing channel 42 away from the guide cap 41 and the inner wall of the main channel; the inner diameter of the diffuser section 47 gradually increases in the flue gas flow direction. The diffuser section 47 forms a wide-angle structure at the end of the mixing channel 42, which allows the gas pressure and flow rate to gradually decrease after the mixed gas enters the diffuser section 47, thereby better ensuring that the reaction products are fully and uniformly mixed.

[0041] Furthermore, such as Figure 1 , Figure 2 and Figure 4As shown, an ammonia injection mixing device for flue gas denitrification according to the present invention includes a dispersion plate 48 disposed within a diffuser section 47. The area of ​​the dispersion plate 48 is smaller than the cross-sectional area of ​​the mixing channel 42, which allows for better guidance of the mixed gas flow in all directions. The dispersion plate 48, the mixing channel 42, and the guide cap 41 are coaxially arranged. When the mixed gas passes through the diffuser section 47, the dispersion plate 48 blocks the flow path of the mixed gas, further reducing its velocity. Under the obstruction of the dispersion plate 48, the mixed gas diffuses and flows in all directions through the space between the dispersion plate 48 and the diffuser section 47, which facilitates better gas mixing. A negative pressure is formed on the other side of the dispersion plate 48, causing the mixed gas to further mix radially under the pressure difference after passing through the dispersion plate 48, thereby improving the mixing efficiency.

[0042] Preferably, the angle between the diffuser section 47 and the wall of the main channel is 20 to 50 degrees, which better guides gas flow. The dispersion plate 48 has the same cross-sectional shape as the main channel 10, either circular or square, which better accommodates the shape and size of the channel. The diameter or side length of the dispersion plate 48 is preferably 0.1 to 0.5 times the inner diameter or side length of the main channel wall.

[0043] According to the present invention, an ammonia mixing device for flue gas denitrification is provided, wherein the atomizing nozzle 30 is preferably connected to a compressed air or steam line 32 in addition to the reducing agent line 31. In specific applications, if the reducing agent is an aqueous urea solution, the compressed air or steam line 32 will provide the compressed air or steam required for atomizing the aqueous urea solution, with a pressure of at least 0.2 MPaG. If the reducing agent is an aqueous ammonia solution, the compressed air or steam line 32 will supply the compressed air or steam required for atomizing the aqueous ammonia solution, with a pressure also not less than 0.2 MPaG. If the reducing agent is ammonia gas, the compressed air or steam line 32 will provide air, steam, or other inert gas for diluting the ammonia gas, and the volume fraction of ammonia after mixing will not exceed 5% vol.

[0044] By connecting the atomizing nozzle 30 to the compressed air or steam pipeline 32, the reducing agent can be effectively atomized, improving its mixing efficiency with the flue gas. Simultaneously, the equipment can flexibly adjust the supplied compressed air or steam to meet the atomization requirements of different reducing agents. This not only improves the equipment's adaptability but also allows for its wide application in various flue gas treatment devices. By optimizing the design of the atomizing nozzle 30 and flexibly adjusting the supply of compressed air or steam, the adaptability and safety of the equipment can be improved while ensuring thorough mixing of the reducing agent and flue gas.

[0045] According to the present invention, an ammonia injection mixing device for flue gas denitrification is provided, wherein the atomizing nozzles 30 in the device have different configuration schemes, which can be configured according to actual needs. For example... Figure 1 As shown, the spray direction of the atomizing nozzle 30 is in the same direction as the flue gas flow; or as... Figure 2 As shown, the spray direction of the atomizing nozzle 30 is opposite to the direction of flue gas flow; or, there are multiple atomizing nozzles 30, some of which spray in the direction of flue gas flow and others spray in the direction of flue gas flow.

[0046] In a preferred embodiment, when the spray direction of the atomizing nozzle 30 is in the same direction as the flue gas flow, the atomizing nozzle 30 is coaxially arranged with the main pipe 10, and the position of the atomizing nozzle 30 is preferably located inside the second pipe section 23; when the spray direction of the atomizing nozzle 30 is opposite to the flue gas flow direction, the atomizing nozzle 30 is coaxially arranged with the main pipe 10, and the position of the atomizing nozzle 30 is preferably located at the outlet of the second pipe section 23. According to this embodiment, the reducing agent spray can preferentially mix with the flue gas flowing out of the inner ring pipe with a slower flow rate, and then, during the flue gas mixing process inside and outside the inner ring pipe, the reducing agent is fully and evenly mixed and reacted with all the flue gas, further preventing the reducing agent from contacting and adhering to the inner wall of the main pipe 10 before it is fully mixed with the flue gas.

[0047] According to any embodiment of the flue gas denitrification ammonia injection mixing device of the present invention, the cross-sectional shape of the main pipe 10 and the inner ring pipe can be set to square or circular according to actual application requirements. Correspondingly, the cross-sectional shape of other functional structures in the main pipe 10 is also set accordingly.

[0048] According to a preferred embodiment of the present invention, when the reducing agent is an aqueous urea solution, as an example, when the aqueous urea solution is sprayed from the atomizing nozzle 30, most of the urea solution will immediately evaporate and decompose into ammonia and HNCO. HNCO is further hydrolyzed into NH3 and CO2, while a small amount of aqueous urea solution located on the outer surface of the spray shape (such as a cone spray) will be sprayed onto the inner wall of the main channel.

[0049] At the inlet of the mixing equipment, flue gas flows through the inner ring pipe and the gap between the inner ring pipe and the main channel. When the flue gas flows through the gap between the reducing pipe section 22 and the main channel, the flue gas velocity gradually increases as the gap narrows. However, when the flue gas accelerates through the annular gap between the second pipe section 23 and the main channel, the flue gas velocity decreases as the flow area gradually increases within the inner ring pipe. But due to inertia, the flue gas continues to flow along the center of the inner ring pipe, creating a negative pressure on the inner wall of the second pipe section 23.

[0050] At the outlet of the second pipe section 23, the pressure distribution from the inner wall of the main channel to the center is positive pressure, negative pressure, and positive pressure, respectively. Therefore, the high-speed flue gas exiting through the annular seam will carry the urea atomized liquid sprayed onto the inner wall of the main channel and flow towards the center, thus preventing it from adhering to and depositing on the inner wall of the main channel.

[0051] Furthermore, the gap between the guide cap and the main channel is gradually narrowing, equivalent to a Venturi structure. After the flue gas and urea solution decomposition products or ammonia vapor undergo preliminary mixing, they are guided through the annular guide groove 43 to the concave side of the guide cap, and finally enter the mixing channel 42. During this process, the mixed gas undergoes at least two direction changes, causing the flue gas flow to change from laminar to turbulent. As a result, the flue gas and urea decomposition products or ammonia vapor mix intensely during this process.

[0052] Finally, the dispersion plate 48 is positioned on the axis of the diffuser section 47 at the outlet of the mixing channel 42. When the mixed gas flows out of the outlet of the mixing channel 42, it passes through the dispersion plate 48. Due to the negative pressure on the back of the dispersion plate 48, the pressure of the mixed gas varies across the pipe cross-section after the dispersion plate 48, causing the mixed gas to move radially after the dispersion plate 48, thus achieving a uniform distribution of the mixed gas across the entire cross-section.

[0053] In summary, the ammonia injection mixing device for flue gas denitrification of the present invention can effectively improve the mixing efficiency of reducing agent and flue gas, and improve the problem of uneven distribution of reactants, thereby improving the denitrification efficiency.

[0054] The ammonia injection mixing device for flue gas denitrification of this invention is particularly suitable for dust-free flue gas denitrification treatment, such as flue gas denitrification of gas-fired boilers, flue gas denitrification of pyrolysis furnaces, and exhaust gas denitrification of diesel / fuel oil engines. In these applications, this device can effectively mix the reducing agent with the flue gas, improving denitrification efficiency. The ammonia injection mixing device for flue gas denitrification can adapt to different operating conditions and requirements. In boiler flue gas denitrification applications, such as... Figure 5 As shown, multiple ammonia injection mixing units for flue gas denitrification can be arranged side-by-side in the cross-section of the flue, with each ammonia injection mixing unit corresponding to at least one atomizing nozzle 30. This arrangement can better adapt to the characteristics of boiler flue gas and denitrification requirements.

[0055] The ammonia injection mixing device for flue gas denitrification of this invention also features various atomizing nozzle 30 configuration schemes, which can be flexibly adjusted according to actual needs. Different configuration schemes can better adapt to different working conditions and requirements, thereby further improving the adaptability and denitrification efficiency of the equipment. The ammonia injection mixing device for flue gas denitrification has a wide range of applications. It can be applied to flue gas denitrification treatment of various types of gas furnaces, pyrolysis furnaces, diesel / fuel oil engines, etc. Furthermore, this equipment can adapt to different flue gas temperature ranges, such as 150–1100℃.

[0056] In summary, the ammonia injection mixing device for flue gas denitrification of the present invention has the characteristics of high efficiency, flexibility and wide application. It can effectively improve the mixing efficiency of reducing agent and flue gas and improve the problem of uneven distribution of reactants, thereby improving denitrification efficiency.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ammonia injection mixing device for flue gas denitrification, characterized in that, include: The main duct (10) has a main channel for flue gas circulation; An inner ring pipe is coaxially arranged within the main channel. The inner ring pipe includes a first pipe section (21), a variable diameter pipe section (22), and a second pipe section (23) in sequence along the flue gas flow direction. The inner diameter of the first pipe section (21) is smaller than that of the second pipe section (23). The distance between the outer surface of the first pipe section (21) and the inner wall of the main channel is greater than that between the outer surface of the second pipe section (23) and the inner wall of the main channel. Atomizing nozzle (30) is provided at the opening of the second pipe section (23) on the side away from the variable diameter pipe section (22), and the atomizing nozzle (30) is connected to the reducing agent pipeline (31). In the direction of flue gas flow, a guide cap (41) is provided downstream of the inner ring pipe. The guide cap (41) has a convex shape on one side and a concave shape on the other side; The protruding side of the guide cap (41) faces the inner ring pipe, and the recessed side of the guide cap (41) faces away from the inner ring pipe. A reverse flow guiding mechanism is provided downstream of the flow guide cap (41); The reverse flow guiding mechanism includes a mixing channel (42) coaxially arranged with the flow guide cap (41). An annular flow guide groove (43) with a groove facing the edge of the flow guide cap (41) is formed between the mixing channel (42) and the inner wall of the main channel, which guides the mixed gas flowing along the pipe wall to the concave side of the flow guide cap (41).

2. The ammonia injection mixing equipment for flue gas denitrification according to claim 1, characterized in that, The cross-sectional shape of the annular guide groove (43) is arc-shaped. The outer edge of the annular guide groove (43) is connected to the inner wall of the main channel. The inner edge of the annular guide groove (43) is located within the projection range of the concave side of the guide cap (41). Alternatively, the reverse flow guiding mechanism includes an outer peripheral flow guide plate (44) and an inner peripheral flow guide plate (45), with the annular flow guide groove (43) formed between the outer peripheral flow guide plate (44) and the inner peripheral flow guide plate (45).

3. The ammonia injection mixing equipment for flue gas denitrification according to claim 2, characterized in that, A support plate (46) is connected between the outer peripheral guide plate (44) and the inner peripheral guide plate (45), and the support plate (46) forms the bottom of the annular guide groove (43); The outer peripheral guide plate (44) is located outside the projection range of the recessed side of the guide cap (41), and the inner peripheral guide plate (45) is located within the projection range of the recessed side of the guide cap (41).

4. The ammonia injection mixing equipment for flue gas denitrification according to claim 1, characterized in that, A diffuser section (47) is provided between the end of the mixing channel (42) away from the guide cap (41) and the inner wall of the main channel. In the direction of flue gas flow, the inner diameter of the diffuser section (47) gradually increases.

5. The ammonia injection mixing device for flue gas denitrification according to claim 4, characterized in that, A dispersion plate (48) is provided inside the diffusion tube section (47); The area of ​​the dispersion plate (48) is smaller than the cross-sectional area of ​​the mixing channel (42); The dispersion plate (48), the mixing channel (42), and the guide cap (41) are arranged coaxially.

6. The ammonia injection mixing device for flue gas denitrification according to any one of claims 1-5, characterized in that, The atomizing nozzle (30) is also connected to a compressed air or steam line (32).

7. The ammonia injection mixing device for flue gas denitrification according to claim 6, characterized in that, The atomizing nozzle (30) sprays in the direction of the flue gas flow; or, the atomizing nozzle (30) sprays in the opposite direction of the flue gas flow; or, there are multiple atomizing nozzles (30), some of which spray in the direction of the flue gas flow and others spray in the opposite direction of the flue gas flow.

8. The ammonia injection mixing device for flue gas denitrification according to any one of claims 1-5, characterized in that, The cross-sectional shape of the main pipe (10) and the inner ring pipe is square or circular.

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