Ammonia spraying and mixing equipment for flue gas denitration

Abstract

The invention provides ammonia spraying and mixing equipment for flue gas denitrification, which comprises a main pipeline, an ammonia spraying and mixing device and an ammonia spraying and mixing device, the inner ring pipeline is coaxially arranged in the main channel, the inner ring pipeline sequentially comprises a first pipe section, a reducing pipe section and a second pipe section in the smoke flowing direction, and the inner diameter of the first pipe section is smaller than that of the second pipe section; the spacing distance between the outer surface of the first pipe section and the inner wall of the main channel is larger than the spacing distance between the outer surface of the second pipe section and the inner wall of the main channel. And the atomizing nozzle is arranged at the opening of the side, away from the reducing pipe section, of the second pipe section, and the atomizing nozzle communicates with the reducing agent pipeline. According to the technical scheme, the problems that reactants are not uniformly distributed and a reducing agent is easily adhered to the inner wall can be solved, so that the denitration effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment, and in particular to an ammonia spraying and mixing device for flue gas denitrification. Background Art

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

[0003] SNCR technology needs to be carried out in a high temperature environment of 850-1100℃, usually in the furnace. When ammonia or urea aqueous solution is sprayed into the furnace in atomized form, ammonia or urea quickly decomposes and reacts with NOx in the flue gas to convert it into N 2 and H 2 O. However, due to the complex combustion and flow field in the furnace, it is difficult to achieve uniform mixing of flue gas and reducing agent by directly injecting the reducing agent into it, so its denitrification efficiency is only about 30%. If the reducing agent is overused, it will cause serious ammonia escape and affect the normal operation of the subsequent SCR.

[0004] For the denitrification of heavy-duty diesel vehicle exhaust or ship engine exhaust, SCR technology is mainly used to ensure that it meets the emission standards. Urea aqueous solution is a commonly used reducing agent. In practical applications, the urea aqueous solution spray of the SCR system is constrained by the exhaust pipe, and the sprayed solution will hit the wall and form a liquid film. The liquid film evaporation absorbs heat, lowers the wall temperature, aggravates the incomplete decomposition of the urea aqueous solution, and produces urea crystals and other sediments, such as biuret and cyanuric acid. This will reduce the utilization rate of the urea aqueous solution and affect the denitrification efficiency. Summary of the invention

[0005] The present invention provides an ammonia spraying and mixing device for flue gas denitrification, which is used to solve the defects in the prior art that the flue gas denitrification effect is not ideal due to the uneven distribution of reactants and the easy adhesion of reducing agents to the inner wall, thereby improving the problems of uneven distribution of reactants and the easy adhesion of reducing agents to the inner wall, thereby improving the denitrification effect.

[0006] The present invention provides an ammonia spraying and mixing device for flue gas denitrification, comprising: a main pipeline, having a main channel for flue gas circulation; an inner ring pipeline, coaxially arranged in 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 circulation direction, the inner diameter of the first pipe section is smaller than that of the second pipe section, and the spacing distance between the outer surface of the first pipe section and the inner wall of the main channel is greater than the spacing distance between the outer surface of the second pipe section and the inner wall of the main channel; an atomizing nozzle, the atomizing nozzle is arranged at an opening of the second pipe section away from the reducing pipe section, and the atomizing nozzle is connected to a reducing agent pipeline.

[0007] According to an ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, a guide cap is arranged downstream of the inner ring pipe in the flue gas flow direction; one side of the guide cap is convex in shape, and the other side is concave in shape; 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 an ammonia spraying and mixing device for flue gas denitrification provided by the present invention, a reverse flow guiding mechanism is arranged downstream of the guide cap; the reverse flow guiding mechanism includes a mixing channel arranged coaxially with the guide cap, and an annular flow guiding groove with a notch facing the edge of the guide cap is formed between the mixing channel and the inner wall of the main channel.

[0009] According to an ammonia spraying and mixing device for flue gas denitrification provided by the present invention, the cross-sectional shape of the annular guide groove is arc-shaped, the outer edge of the annular guide groove is connected to the inner wall of the main channel, and the inner edge of the annular guide groove is located within the projection range of the recessed 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 groove is formed between the outer peripheral guide plate and the inner peripheral guide plate.

[0010] According to an ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, 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 recessed side of the guide cap, and the inner peripheral guide plate is located within the projection range of the recessed side of the guide cap.

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

[0012] According to an ammonia spraying and mixing device for flue gas denitrification provided by the present invention, a dispersion plate is arranged in the diffusion pipe 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 hood are coaxially arranged.

[0013] According to the ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, the atomizing nozzle is also connected to a compressed air or steam pipeline.

[0014] According to an ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, the spraying direction of the atomizing nozzle is in the same direction as the flow direction of the flue gas; or, the spraying direction of the atomizing nozzle is opposite to the flow direction of the flue gas; or, there are multiple atomizing nozzles, some of which have spraying directions in the same direction as the flow direction of the flue gas, and other atomizing nozzles have spraying directions opposite to the flow direction of the flue gas.

[0015] According to the ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, the cross-sectional shape of the main pipeline and the inner ring pipeline is square or circular.

[0016] The ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention realizes flue gas denitrification by reacting the reducing agent sprayed by the atomizing nozzle with the flue gas in the main channel. The main feature of the equipment is to use the variable diameter pipe section and the inner ring pipe to realize the mixing of flue gas and the uniform distribution of the reducing agent. In the inner ring pipe, when the flue gas flows from the first pipe section to the second pipe section, the air pressure decreases and the flow rate slows down due to the change in the pipe diameter. At the same time, since the spacing distance between the outer surface of the first pipe section and the inner wall of the main channel is greater than the spacing distance between the outer surface of the second pipe section and the inner wall of the main channel, the flue gas circulating in the gap between the inner ring pipe and the main channel increases the air pressure and the flow rate becomes faster after passing through the outer side of the variable diameter pipe section. When the atomizing nozzle sprays the reducing agent, the high-speed flue gas near the edge of the main channel can entrain the atomized reducing agent to move, preventing the reducing agent from adhering to the pipe wall. In addition, due to the pressure difference between the flue gas flowing inside and outside the inner ring pipe, the flue gas will be radially mixed in the main channel after passing through the inner ring pipe, which is conducive to improving the mixing efficiency of the reducing agent and the flue gas and making the mixed gas more uniform. Therefore, the ammonia spray mixing equipment for flue gas denitrification can improve the problems of uneven distribution of reactants and easy adhesion of the reducing agent to the inner wall, thereby improving the denitrification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0020] Figure 3 It is a schematic diagram of the top view of the structure of the ammonia spraying and mixing device for flue gas denitration provided by the present invention;

[0021] Figure 4 It is a schematic diagram of the local structural dimensions of the ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention;

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

[0023] Reference numerals:

[0024] 10. Main pipeline; 21. First pipe section; 22. Reducer pipe section; 23. Second pipe section; 30. Atomizing nozzle; 31. Reductant pipeline; 32. Compressed air or steam pipeline; 41. Guide hood; 42. Mixing channel; 43. Annular guide groove; 44. Outer guide plate; 45. Inner guide plate; 46. Support plate; 47. Diffuser pipe section; 48. Disperser plate. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0027] Combine the following Figure 1-Figure 5 The specific implementation of the ammonia spraying and mixing equipment for flue gas denitrification of the present invention is described.

[0028] The present invention provides an ammonia spraying and mixing device for flue gas denitration, which realizes flue gas denitration by reacting the reducing agent sprayed by the atomizing nozzle 30 with the flue gas in the main channel. The main feature of the device is that the reducing pipe section 22 and the inner ring pipe are used to achieve the mixing of the flue gas and the uniform distribution of the reducing agent. Figure 1 , Figure 2 and Figure 3 As shown, it includes: a main pipe 10, which has a main channel for smoke circulation; an inner ring pipe, which is coaxially arranged in the main channel, and the inner ring pipe includes a first pipe section 21, a reducing pipe section 22 and a second pipe section 23 in sequence along the smoke circulation direction, the inner diameter of the first pipe section 21 is smaller than the second pipe section 23, and the spacing distance between the outer surface of the first pipe section 21 and the inner wall of the main channel is greater than the spacing distance between the outer surface of the second pipe section 23 and the inner wall of the main channel; an atomizing nozzle 30, which is arranged at the opening of the second pipe section 23 away from the reducing pipe section 22, and the atomizing nozzle 30 is connected to the reducing agent pipeline 31.

[0029] In the inner ring pipe, when the flue gas flows from the first pipe section 21 to the second pipe section 23, the air pressure is reduced and the flow rate is slowed down due to the change in pipe diameter. At the same time, since 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 increases in air pressure and increases in flow rate after passing through the outer side 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 to move, preventing the reducing agent from adhering to the pipe wall. In addition, due to the pressure difference between the flue gas flowing inside and outside the inner ring pipe, the flue gas produces radial mixing in the main channel after passing through the inner ring pipe, which is conducive to improving the mixing efficiency of the reducing agent and the flue gas and making the mixed gas more uniform. Therefore, the ammonia spraying mixing equipment for flue gas denitrification can improve the problem of uneven distribution of reactants and the problem of the reducing agent easily adhering to the inner wall, thereby improving 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 diameter-reducing pipe section 22 is between 150 and 175 degrees; the angle between the diameter-reducing pipe section 22 and the second pipe section 23 is between 150 and 175 degrees. In order to ensure the smoke 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, according to the ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, a guide hood 41 is arranged downstream of the inner ring pipe in the flue gas flow direction. One side of the guide hood 41 is convex and the other side is concave; the convex side of the guide hood 41 faces the inner ring pipe, and the concave side of the guide hood 41 faces away from the inner ring pipe.

[0033] After the flue gas flows through the atomizing nozzle 30, the convex side of the guide cap 41 plays a guiding role, and the mixed gas of the flue gas and the reducing agent gas continues to flow along the edge of the guide cap 41. In 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, thereby promoting further radial mixing of the mixed gas after passing through the guide cap 41, thereby accelerating the reaction of the flue gas and the reducing agent.

[0034] The raised side of the guide cap 41 is preferably in a smooth arc shape, which 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, according to the ammonia spraying and mixing equipment for flue gas denitrification provided by the present invention, a reverse flow guiding mechanism is provided downstream of the flow guide 41. Figure 1 and Figure 2 As shown, the reverse flow guiding mechanism includes a mixing channel 42 coaxially arranged with the flow guiding cap 41 , and an annular flow guiding groove 43 with a notch facing the edge of the flow guiding cap 41 is formed between the mixing channel 42 and the inner wall of the main channel.

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

[0037] According to the above-mentioned ammonia spraying and mixing device for flue gas denitrification, the cross-sectional shape of the annular guide groove 43 can be an arc, wherein the outer edge of the annular guide groove 43 is connected to the inner wall of the main channel, and the inner edge of the annular guide groove 43 is located within the projection range of the concave side of the guide hood 41. The cross-sectional shape of the annular guide groove 43 is an arc, which can effectively guide the mixed gas flowing along the pipeline wall to the concave side of the guide hood 41, thereby better guiding the mixed gas to flow toward the center.

[0038] Alternatively, the reverse flow guide mechanism may include an outer peripheral flow guide plate 44 and an inner peripheral flow guide plate 45, and an annular flow guide groove 43 is formed between the outer peripheral flow guide plate 44 and the inner peripheral flow guide plate 45. The outer peripheral flow guide plate 44 is connected to the inner wall of the main channel, and the end of the inner peripheral flow guide plate 45 extends to the projection range of the concave side of the flow guide cap 41. After the mixed gas passes through the flow guide cap 41, it is first guided by the outer peripheral flow guide plate 44, so that the mixed gas flows toward the inner peripheral flow guide plate 45, and then the mixed gas is guided by the inner peripheral flow guide plate 45 so that the mixed gas flows toward the concave side of the flow guide cap 41.

[0039] Furthermore, in order to better guide the mixed gas, an arc chamfer may be provided between the outer guide plate 44 and the inner guide plate 45, or, according to the ammonia spraying mixing device for flue gas denitrification provided by the present invention, a support plate 46 is connected between the outer guide plate 44 and the inner 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 reverse flow guide mechanism can make the flow guiding effect of the mixed gas smoother. After the mixed gas passes through the guide cap 41, it is first guided by the outer peripheral guide plate 44, so that the mixed gas flows toward the support plate 46, and then the mixed gas moves along the support plate 46 to the inner peripheral guide plate 45, and then is guided by the inner peripheral guide plate 45 so that the mixed gas flows toward 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, according to an ammonia spraying and mixing device for flue gas denitrification provided by the present invention, a diffusion pipe section 47 is arranged between the end of the mixing channel 42 away from the guide hood 41 and the inner wall of the main channel; in the flue gas flow direction, the inner diameter of the diffusion pipe section 47 gradually increases. The diffusion pipe section 47 forms a wide-angle structure at the end of the mixing channel 42, which can gradually reduce the gas pressure and flow rate of the mixed gas after entering the diffusion pipe section 47, so as to better mix the reaction products fully and evenly.

[0041] Furthermore, if Figure 1 , Figure 2 and Figure 4As shown, according to an ammonia spray mixing device for flue gas denitrification provided by the present invention, a dispersion plate 48 is arranged in the diffusion pipe section 47. The area of ​​the dispersion plate 48 is smaller than the cross-sectional area of ​​the mixing channel 42, which can better guide the mixed gas to flow around. The dispersion plate 48, the mixing channel 42 and the guide cap 41 are coaxially arranged. When the mixed gas passes through the diffusion pipe section 47, the dispersion plate 48 blocks the flow path of the mixed gas, which plays a role in further reducing the flow rate of the mixed gas. Under the obstruction of the dispersion plate 48, the mixed gas diffuses and flows around through the space between the dispersion plate 48 and the diffusion pipe section 47. This flow mode helps the gas to mix better. A negative pressure is formed on the other side of the dispersion plate 48, so that the mixed gas is further radially mixed under the action of 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, and this angle design can better guide the gas flow. The cross-sectional shape of the dispersion plate 48 is the same as that of the main pipeline 10, which is round or square, and this design can better adapt to the shape and size of the pipeline. 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 wall of the main channel.

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

[0044] By connecting the atomizing nozzle 30 to the compressed air or steam pipeline 32, the atomization of the reducing agent can be effectively achieved, and the mixing efficiency between the reducing agent and the flue gas can be improved. At the same time, for different reducing agents, the equipment can flexibly adjust the compressed air or steam supplied to meet the needs of atomization of different reducing agents. This not only improves the adaptability of the equipment, but also enables it to be widely used in various flue gas treatment equipment. 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 that the reducing agent and the flue gas are fully mixed.

[0045] According to the ammonia spraying and mixing device for flue gas denitrification provided by the present invention, the atomizing nozzle 30 in the device has different setting schemes and can be set according to actual needs. Figure 1 As shown, the spray direction of the atomizing nozzle 30 is along the direction of smoke flow; or Figure 2 As shown, the spray direction of the atomizing nozzle 30 is opposite to the flow direction of the smoke; or, there are multiple atomizing nozzles 30, of which the spray direction of some atomizing nozzles 30 is in the same direction as the flow direction of the smoke, and the spray direction of other atomizing nozzles 30 is opposite to the flow direction of the smoke.

[0046] Preferably, when the spray direction of the atomizing nozzle 30 is in the direction of 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 in the second pipe section 23; when the spray direction of the atomizing nozzle 30 is in the direction of 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 at the outlet of the second pipe section 23. According to this embodiment, the reducing agent spray can be preferentially mixed with the flue gas flowing out of the inner ring pipe with a slower flow rate, and then in the process of mixing the flue gas inside and outside the inner ring pipe, the reducing agent is fully and evenly mixed with all the flue gas to further prevent the reducing agent from contacting and adhering to the inner wall of the main pipe 10 before being fully mixed with the flue gas.

[0047] According to any embodiment of the ammonia spraying and mixing equipment for flue gas denitrification of the present invention, the cross-sectional shapes of the main pipeline 10 and the inner ring pipeline can be set to square or circular according to actual application requirements, and correspondingly, the cross-sectional shapes of other functional structures in the main pipeline 10 are also set accordingly.

[0048] According to a preferred embodiment of the present invention, when the reducing agent is a urea aqueous solution, when the urea aqueous solution is sprayed from the atomizing nozzle 30, most of the urea solution will evaporate and decompose into ammonia and HNCO. HNCO is further hydrolyzed into NH 3 and CO 2 , while a small amount of urea aqueous solution located on the outer surface of the injection shape (such as conical spray) will be sprayed onto the inner wall of the main channel.

[0049] At the entrance of the mixing device, the 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 flow rate gradually increases due to the narrowing gap. However, when the flue gas accelerates through the annular gap between the second pipe section 23 and the main channel, the flue gas flow rate decreases due to the gradual increase in the flow area when the flue gas passes through the inner ring pipe. However, due to inertia, the flue gas will continue to flow along the center of the inner ring pipe and form a negative pressure on the inner wall side of the second pipe section 23.

[0050] On the cross section 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 in sequence. Therefore, the high-speed flue gas coming out of the annular gap will entrain the urea atomized liquid sprayed on the inner wall of the main channel and flow toward the center, thereby preventing it from adhering to and depositing on the inner wall of the main channel.

[0051] In addition, the gap between the guide cap and the main channel is a tapered type, which is equivalent to a Venturi structure. After the flue gas and the decomposition products of the urea aqueous solution or the ammonia vapor are initially mixed, they will be guided to the concave side of the guide cap through the annular guide groove 43 and finally enter the mixing channel 42. In this process, the mixed gas will undergo at least two changes of direction, so that the flow of the flue gas changes from laminar flow to turbulent flow. In this way, the flue gas and the decomposition products of the urea aqueous solution or the ammonia vapor will be violently mixed here.

[0052] Finally, the dispersion plate 48 is arranged on the axis of the diffusion pipe section 47 at the outlet of the mixing channel 42. When the mixed gas flows out from the outlet of the mixing channel 42, it passes through the dispersion plate 48. Since the back of the dispersion plate 48 is under negative pressure, the pressure of the mixed gas in the pipe cross section after the dispersion plate 48 is different, so that the mixed gas moves radially after the dispersion plate 48, and the mixed gas is evenly distributed in the entire cross section.

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

[0054] The ammonia spraying and mixing equipment for flue gas denitrification of the present invention is particularly suitable for the denitrification of dust-free flue gas, such as gas furnace flue gas denitrification, cracking furnace flue gas denitrification, diesel / fuel oil engine exhaust denitrification, etc. In these application scenarios, the equipment can effectively mix the reducing agent with the flue gas to improve the denitrification efficiency. The ammonia spraying and mixing equipment for flue gas denitrification can adapt to different working conditions and requirements. In the application of boiler flue gas denitrification, such as Figure 5 As shown, multiple ammonia spraying mixed monomer devices for flue gas denitration can be arranged in parallel in the flue cross section, and each ammonia spraying mixed monomer device is correspondingly provided with at least one atomizing nozzle 30. This arrangement can better adapt to the characteristics of boiler flue gas and denitration requirements.

[0055] The ammonia spraying and mixing equipment for flue gas denitrification of the present invention also has a variety of different atomizing nozzle 30 setting schemes, which can be flexibly adjusted according to actual needs. Different setting schemes can better adapt to different working conditions and needs, thereby further improving the adaptability and denitrification efficiency of the equipment. The ammonia spraying and mixing equipment 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, cracking furnaces, diesel / fuel oil engines and other equipment. At the same time, the equipment can also adapt to different flue gas temperature ranges, such as 150 to 1100°C.

[0056] In summary, the ammonia spraying and mixing equipment 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 the reducing agent and the flue gas and improve the problem of uneven distribution of reactants, thereby improving the denitrification efficiency.

[0057] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Ammonia spraying and mixing equipment for flue gas denitrification, It is characterized in that include: A main duct (10) having a main passage for smoke circulation; an inner ring pipe coaxially arranged in the main channel, the inner ring pipe comprising a first pipe section (21), a diameter-reducing pipe section (22) and a second pipe section (23) in sequence along the smoke flow direction, the inner diameter of the first pipe section (21) being smaller than that of the second pipe section (23), and the spacing distance between the outer surface of the first pipe section (21) and the inner wall of the main channel being greater than the spacing distance between the outer surface of the second pipe section (23) and the inner wall of the main channel; An atomizing nozzle (30), the atomizing nozzle (30) being arranged at an opening of the second pipe section (23) on a side away from the reducing pipe section (22), and the atomizing nozzle (30) being connected to a reducing agent pipeline (31).

2. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 1, It is characterized in that In the direction of smoke flow, a guide cap (41) is provided downstream of the inner ring pipe; One side of the guide cap (41) is convex, and the other side is concave; The convex side of the flow guide cap (41) faces the inner ring pipe, and the concave side of the flow guide cap (41) faces away from the inner ring pipe.

3. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 2, It is characterized in that A reverse flow guiding mechanism is arranged downstream of the flow guiding cap (41); The reverse flow guiding mechanism comprises a mixing channel (42) coaxially arranged with the flow guiding cap (41), and an annular flow guiding groove (43) with a notch facing the edge of the flow guiding cap (41) is formed between the mixing channel (42) and the inner wall of the main channel.

4. The ammonia spraying and mixing device for flue gas denitrification according to claim 3, It is characterized in that The cross-sectional shape of the annular guide groove (43) is an arc, the outer edge of the annular guide groove (43) is connected to the inner wall of the main channel, and 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 guide mechanism comprises an outer peripheral flow guide plate (44) and an inner peripheral flow guide plate (45), and the annular flow guide groove (43) is formed between the outer peripheral flow guide plate (44) and the inner peripheral flow guide plate (45).

5. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 4, It is 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 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).

6. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 3, It is characterized in that A diffusion pipe section (47) is provided between one end of the mixing channel (42) away from the guide cap (41) and the inner wall of the main channel; In the smoke flow direction, the inner diameter of the diffusion pipe section (47) gradually increases.

7. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 6, It is characterized in that A dispersion plate (48) is arranged in the diffusion pipe 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 coaxially arranged.

8. The ammonia spraying and mixing device for flue gas denitrification according to any one of claims 1 to 7, It is characterized in that The atomizing nozzle (30) is also connected to a compressed air or steam pipeline (32).

9. The ammonia spraying and mixing equipment for flue gas denitrification according to claim 8, It is characterized in that The spray direction of the atomizing nozzle (30) is in the direction of the flow of the smoke; or, the spray direction of the atomizing nozzle (30) is in the direction opposite to the flow of the smoke; or, there are a plurality of atomizing nozzles (30), wherein the spray direction of a portion of the atomizing nozzles (30) is in the direction of the flow of the smoke, and the spray direction of another portion of the atomizing nozzles (30) is in the direction opposite to the flow of the smoke.

10. The ammonia spraying and mixing device for flue gas denitrification according to any one of claims 1 to 7, It is characterized in that The cross-sectional shapes of the main pipeline (10) and the inner ring pipeline are square or circular.

Images