Static mixer and SCR flue gas denitration ammonia injection mixing system

Abstract

This invention discloses a static mixer and an SCR flue gas denitrification ammonia injection mixing system. The static mixer is installed in the flue and includes multiple static mixing components, a groove, and a second row of ash pipes. Each static mixing component includes: a narrowing section, which is a hollow tubular structure with an upper opening area smaller than its lower opening area; a guide section located above the narrowing section; and at least one turbulence section, which is a concave hollow structure with an upper opening located below or inside the narrowing section, with its bottom connected to the first row of ash pipes. The first row of ash pipes is used to discharge dust from the turbulence section into the flue. This invention can improve the uniformity of ammonia mixing with flue gas while removing dust from the flue gas, thereby mitigating blockage of ammonia nozzles, catalyst bed pores in flue gas denitrification technology, and downstream equipment, thus reducing ammonia escape and effectively overcoming a series of problems caused by ammonia escape.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, and in particular to a static mixer and an SCR flue gas denitrification ammonia injection mixing system. Background Technology

[0002] Among flue gas denitrification methods, the most widely used and technologically mature in industrial applications is Selective Catalytic Reduction (SCR) denitrification technology. The principle of SCR denitrification technology is to inject ammonia, a reducing agent, into flue gas at 280℃~420℃ through an ammonia injection mixing system. A static mixer ensures uniform mixing of the ammonia and flue gas. Under the action of the SCR denitrification catalyst, ammonia (NH3) reduces nitrogen oxides (NOx) in the flue gas. x The mixture is reduced to non-toxic and non-polluting nitrogen and water, thereby achieving NO removal from the mixed gas. x The purpose.

[0003] The national standard GB / T 34339-2017, "Ammonia Injection Mixing System for Coal-fired Flue Gas Denitrification," defines an ammonia injection mixing system as a system in which ammonia gas, diluted with air, is injected into the inlet flue of an SCR reactor and uniformly mixed with the flue gas. GB / T 34339-2017 further divides the ammonia injection mixing system into two types: an ammonia injection grid (AIG) and a static ammonia mixer. The static ammonia mixer is defined as a device that uses fixed components to change the flow state of ammonia gas and flue gas, thereby achieving thorough mixing and obtaining a higher NH3 / NO3 ratio. x Mixing efficiency. Typical static ammonia mixers have various structural forms, such as vortex, swirl, longitudinal vortex, and V-type.

[0004] Ammonia injection mixing systems are typically located before dust collectors. The high dust content in flue gas easily leads to nozzle clogging. Large amounts of dust enter the SCR catalyst bed through the ammonia injection mixing system, potentially causing localized blockage of the catalyst bed pores. In recent years, due to factors such as slowing economic growth, increased environmental pressure, and pandemic control measures, the utilization hours of coal-fired units, heating furnaces, incinerators, and waste heat boilers have been declining, with some operating at low loads for extended periods. This reduces flue gas volume and consequently, ammonia injection volume, making nozzles even more prone to clogging.

[0005] The ammonia injection rate of a clogged ammonia nozzle is very low or even zero, while the ammonia injection rate of other unclogged ammonia nozzles increases. This causes a large difference in the ammonia-nitrogen molar ratio within the same flue cross-section, resulting in a poor uniformity of the ammonia-nitrogen molar ratio distribution at the catalyst inlet of the SCR reactor. In areas with insufficient ammonia injection, the NOx reaction is incomplete and the denitrification efficiency is reduced. In areas with excessive ammonia injection, excess ammonia that has not participated in the denitrification reaction enters the flue gas, resulting in ammonia escape.

[0006] A large amount of dust in the flue gas enters the SCR catalyst bed after passing through the ammonia injection mixing system, which can easily cause catalyst poisoning and localized blockage of the bed pores. Larger dust particles can easily wear down the catalyst bed, causing thinning of the catalyst pore walls, reducing the catalyst's service life, and affecting the long-term operation of the unit. At the same time, the denitrification efficiency decreases, the ammonia utilization rate decreases, and ammonia escape also occurs. The escaped ammonia in the SCR denitrification system reacts with SO3 in the flue gas to form ammonium bisulfate (ABS), causing severe blockage or leakage in downstream equipment such as air preheaters or economizers, threatening the safe and economical operation of the boiler / unit. If there is a wet desulfurization unit downstream, it can cause problems such as substandard gypsum products (limestone / lime-gypsum method) or excessive ammonia nitrogen in the desulfurization wastewater (sodium alkali desulfurization method). The escaped ammonia will cause secondary pollution after being discharged into the atmosphere. Summary of the Invention

[0007] The purpose of this invention is to provide a static mixer and an SCR flue gas denitrification ammonia injection mixing system. The static mixer of this invention improves the uniformity of ammonia and flue gas mixing while removing dust from the flue gas, thereby reducing the blockage of ammonia nozzles, catalyst bed channels in flue gas denitrification technology, and downstream equipment, thus reducing ammonia escape. This effectively overcomes the problems caused by ammonia escape, such as blockage and corrosion leakage in air preheaters or economizers, excessive ammonia nitrogen in desulfurization wastewater or unqualified gypsum products in subsequent treatment, and secondary pollution.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a static mixer is provided, which is one or more layers disposed in a flue, comprising: a plurality of static mixing components arranged side by side; each static mixing component comprising: a narrowing section, which is a hollow tubular structure with an upper end opening area smaller than a lower end opening area; a guide section, located above the narrowing section, having an inverted concave structure, for guiding flue gas leaving the narrowing section to collide with flue gas leaving adjacent static mixing components; at least one turbulence section, which is a concave hollow structure with an upper end opening, located below or inside the narrowing section, the bottom of the turbulence section communicating with a first row of ash pipes; and a first row of ash pipes for discharging dust from the turbulence section into the flue.

[0009] A groove is formed by a sealed connection between two adjacent static mixing components to collect falling dust.

[0010] The second row of ash pipes is connected to the groove through ash discharge holes and is used to discharge the dust in the groove.

[0011] In the static mixer of the present invention, a certain gap may also be provided between two adjacent static mixing components as a dust discharge channel. The lower part of the dust discharge channel is connected to a dust collection trough, which is sealed to the reduced diameter section for collecting falling dust. The third dust discharge pipe is connected to the dust collection trough for discharging the dust in the dust collection trough.

[0012] Furthermore, in the above technical solution, the cross-sectional area of ​​the ash collection trough is larger than the cross-sectional area of ​​the ash discharge channel.

[0013] Furthermore, in the above technical solution, an inclined tube is provided at the bottom of the static mixing component, and the first row of ash pipes, the second row of ash pipes and the third row of ash pipes are all connected to the inclined tube, through which the dust is discharged from the flue.

[0014] Furthermore, in the above technical solution, the shape of the upper and lower end faces of the reduced diameter section can be circular, elliptical, square, rectangular, or polygonal, but the present invention is not limited thereto.

[0015] Furthermore, in the above technical solution, the lower end face of the guide section is lower than the upper end face of the narrowing section, which is used to guide the flue gas to flow obliquely downward.

[0016] Furthermore, in the above technical solution, the turbulence section is preferably one or more of the following structures: hemispherical, semi-ellipsoidal, inverted cone, inverted square pyramid, wine glass, and petal.

[0017] Furthermore, in the above technical solution, a wind baffle is provided above the groove, preferably a straight or curved plate that is connected to the diameter reduction section and tilted downwards.

[0018] The working process of the static mixer of the present invention is as follows: Flue gas flows through the turbulence section, forming vortices and colliding with the back of the section. Simultaneously, the flue gas collides with the inner wall of the narrowing section, and some dust in the flue gas falls into the turbulence section, exiting the flue through the first row of ash pipes and inclined pipes, achieving the first separation of dust and flue gas. As the flue gas flows through the narrowing section, the flow area gradually decreases, and the flow velocity increases, increasing the probability of dust collisions in the flue gas. Some of the dust particles aggregate into larger particles, which are more easily removed from the flue gas. During this process, some dust particles fall into the turbulence section under their own gravity or after colliding with the inner wall of the narrowing section, thus achieving the second removal of dust. The flue gas leaves the narrowing section... In the narrowing section, the flue gas flows through the channel formed by the guide section and the narrowing section. The direction of the flue gas changes from upward to downward. Under the action of inertial force and its own gravity, some of the dust in the flue gas enters the groove or enters the ash collection tank through the ash discharge channel. The flue gas collides with the flue gas leaving the adjacent static mixing component. After the collision between dust particles with similar particle sizes, the horizontal forces cancel each other out, and the vertical forces are superimposed to accelerate the dust into the groove or into the ash collection tank through the ash discharge channel, realizing the rapid separation of dust and flue gas, increasing the dust removal rate and removal efficiency. The dust that enters the groove or enters the ash collection tank through the ash discharge channel is discharged from the flue through the second or third ash discharge pipe or the inclined pipe, realizing the third dust removal.

[0019] According to a second aspect of the present invention, the present invention provides a flue gas denitrification ammonia injection mixing system, comprising, in sequence along the flue gas flow direction: an ammonia injection assembly, including an ammonia nozzle, an ammonia injection branch pipe and an ammonia injection main pipe, wherein the ammonia nozzle is connected to the ammonia injection main pipe through the ammonia injection branch pipe; and a static mixer as described in any of the above technical solutions, wherein a static mixing component in the static mixer is disposed corresponding to the ammonia nozzle.

[0020] Furthermore, in the above technical solution, each static mixing component corresponds to the same number of ammonia nozzles.

[0021] Furthermore, in the above technical solution, the ammonia nozzle corresponds one-to-one with the flow guide section of the static mixing component and is located directly below the turbulence section.

[0022] The ammonia mixing mechanism of this invention is as follows: The ammonia nozzle is arranged directly below the guide section of the static mixing component. After the ammonia gas is ejected from the nozzle, it encounters the turbulence section, transforming from a single stream of ammonia gas into a stream surrounding the turbulence section, increasing the dispersion of ammonia gas in the flue gas. When the static mixing component is equipped with multiple turbulence sections, it is even more beneficial for the dispersion of ammonia gas in the flue gas. When the flue gas and ammonia gas flow through the area between the turbulence section and the narrowing section, the flue gas flow area decreases, the gas velocity increases, and the collision and mixing between the flue gas and ammonia gas, as well as between the flue gas and the narrowing section, intensifies, enhancing the mixing of ammonia gas and flue gas. After passing through the turbulence section, the gas forms a vortex and collides after the turbulence section, further enhancing the mixing of ammonia gas and flue gas. As the flue gas flows through the narrowing section after being turbulent, the flow area gradually decreases again, the gas velocity increases, and the collision and mixing between the flue gas and ammonia, as well as between the flue gas and the narrowing section, intensifies, thus strengthening the mixing of ammonia and flue gas. After leaving the narrowing section, the gas collides with the guide section, and the gas flow direction changes. During this process, the collision with the wall and the change in flow direction further enhance the mixing of ammonia and flue gas. The gas leaves the static mixing component through the channel between the narrowing section and the guide section and collides with the flue gas of the adjacent static mixing component. The two mixed flue gas streams are forcibly mixed, which effectively enhances the mixing effect of flue gas and ammonia, improves the uniformity of gas mixing, and thus shortens the distance required for uniform mixing.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The static mixer of the present invention can not only pre-remove dust from flue gas, thus acting as a pre-dust collector, but also mix ammonia with flue gas, thus acting as a mixer.

[0025] 2. The static mixing component in the static mixer of the present invention achieves three-stage dust removal through structural design, and can effectively prevent the removed dust from being blown up by the flue gas again to form secondary entrainment. Therefore, it can effectively achieve pre-removal of dust in the flue gas, especially for dust with larger particle size in the flue gas, thereby reducing the clogging of ammonia nozzles, effectively reducing the wear of SCR denitrification catalyst, extending the service life of the catalyst, and thus reducing ammonia escape and mitigating the problems of downstream equipment blockage and leakage, unqualified gypsum products, or excessive ammonia nitrogen in desulfurization wastewater and air pollution caused by ammonia escape.

[0026] 3. In the static mixing component of the present invention, due to the setting of the guide section, groove, and ash collection trough, the ash accumulated at the flue support and bends above the static mixer will fall off in large pieces due to the impact or disturbance of the flowing flue gas. The large pieces of dust that fall off can stay on the guide section or fall into the groove or ash collection trough, thereby preventing the dust from falling from the narrowing section to the ammonia nozzle. The present invention sets the turbulence section of the static mixing component directly above the ammonia nozzle and corresponds one-to-one with the ammonia nozzle. The turbulence section is a concave hollow structure with an open upper end face, which can effectively collect the dust falling above it and effectively prevent the falling dust from falling into the ammonia nozzle. The static mixer of this invention achieves a "dust-proof" function, avoiding uneven ammonia injection caused by dust clogging the nozzles, which can improve denitrification efficiency. This ensures normal ammonia injection throughout the entire operating cycle of the denitrification device, thereby guaranteeing the uniformity of ammonia on the same flue cross-section. It also ensures that the entire denitrification catalyst bed can be effectively utilized, reducing ammonia escape rate and minimizing blockage or leakage in downstream air preheaters or economizers, thus extending the maintenance cycle and service life of the device.

[0027] 4. In the static mixing component of the present invention, a baffle plate is provided above the groove, thereby blocking most of the flue gas above the groove, preventing a large amount of flue gas from entering the groove and blowing up the dust. Even if a small amount of flue gas entering the ash collection trough can blow up the dust, most of the blown dust will fall back into the groove under the action of the baffle plate, effectively avoiding secondary entrainment of dust. Furthermore, a certain gap exists between two adjacent narrowing sections as an ash discharge channel, and the lower part of the ash discharge channel is connected to an ash collection trough, the cross-sectional area of ​​which is larger than the cross-sectional area of ​​the ash discharge channel. The cross-sectional area is equivalent to setting up a "baffle" above the ash collection trough, thereby blocking the flue gas above the ash collection trough and preventing the flue gas from entering the ash collection trough and blowing up the dust. Even if a small amount of flue gas enters the ash collection trough and blows up the dust, the blown dust will fall back into the groove under the action of the curved section, which basically eliminates the secondary entrainment of dust. The baffle is set at an angle downward, so that the dust falling on the baffle can slide down into the groove or ash collection trough under the action of the flue gas, avoiding the accumulation of dust on the baffle to form scale or caking.

[0028] 5. In the static mixing component of the present invention, when there is a certain gap between two adjacent reduced diameter sections, under abnormal operating conditions such as flue gas flow deviation, flue gas temperature rises sharply, or local temperature of flue cross section is too high, the gap between the reduced diameter sections and the structure of the ash collection trough can effectively buffer the thermal expansion caused by excessive local temperature, prevent local deformation and equipment damage, and facilitate the stable long-term operation of the device.

[0029] 6. The static mixer can be set in multiple layers, and the size of the static mixing components can be different. It can realize the impact mixing of flue gas in different areas of the flue, enhance the mixing uniformity of ammonia and flue gas, reduce the gas velocity distribution deviation and ammonia concentration distribution deviation on the same cross section of the flue, thereby improving the denitrification rate of flue gas and the utilization rate of catalyst, and thus reducing ammonia escape.

[0030] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a flue gas denitrification ammonia injection mixing system according to the present invention (arrows indicate the direction of gas flow).

[0032] Figure 2 yes Figure 1 A top view of the static mixing components of the denitrification ammonia spraying mixing system shown.

[0033] Figure 3 yes Figure 1 A top view of the ammonia injection assembly of the denitrification ammonia injection mixing system shown.

[0034] Figure 4 This is a schematic diagram of a flue gas denitrification ammonia injection mixing system according to the present invention (arrows indicate the direction of gas flow).

[0035] Figure 5 yes Figure 4 A top view of the static mixing components of the denitrification ammonia spraying mixing system shown.

[0036] Key reference numerals: 100-Fluid duct; 200-Static mixing assembly; 201-Reduced diameter section; 202-Guiding section; 203-Turbulence section; 204-First ash discharge pipe; 205-Inclined pipe; 206-Valve; 208-First fixing rod; 209-Second fixing rod; 300-Groove; 301-Second ash discharge pipe; 302-Ash discharge hole; 303-Ash discharge channel; 304-Wind baffle; 305-Ash collection trough; 306-Third ash discharge pipe; 400-Ammonia injection assembly; 401-Ammonia nozzle; 402-Ammonia injection branch pipe; 403-Ammonia injection main pipe. Detailed Implementation

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0038] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0039] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” other elements or features will be oriented “above” the element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. Objects may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0040] In this document, the terms "first," "second," and "third," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," and "third," etc., can also be used interchangeably.

[0041] According to a first aspect of the present invention, a static mixer is provided, such as Figures 1-5 As shown, the static mixer is a single layer (such as...) Figure 1 , Figure 4 (As shown) or multiple layers (not shown in the attached diagram), disposed in the flue 100, including:

[0042] Multiple static mixing components 200 arranged side by side include: a narrowing section 201, which is a hollow tubular structure with an upper end opening area smaller than the lower end opening area; a guide section 202, located above the narrowing section 201, which is an inverted concave structure used to guide the flue gas leaving the narrowing section 201 to collide with the flue gas leaving adjacent static mixing components 200; at least one turbulence section 203, which is a concave hollow structure with an upper end opening, located below or inside the narrowing section 201, and the bottom of the turbulence section 203 is connected to a first row of ash pipes 204; the first row of ash pipes 204 is used to discharge dust in the turbulence section 203 into the flue duct 100. A groove 300 is formed by a sealed connection between two adjacent static mixing components 200, used to collect falling dust; a second row of ash pipes 301 is connected to the groove 300 through an ash discharge hole 302, used to discharge dust in the groove 300. Preferably, but not limitingly, the guide section 202 is a square pyramid shape (e.g., Figures 1-2 (as shown), pyramidal, conical, frustum-shaped (such as) Figures 4-5 (As shown), inverted hemispherical, inverted semi-ellipsoidal, and inverted wine glass shape.

[0043] The static mixer of the present invention, such as Figure 4 , Figure 5 As shown, a certain gap can also be provided between two adjacent static mixing components 200 as a dust discharge channel 303. The lower part of the dust discharge channel 303 is connected to a dust collection trough 305, which is sealed to the reduced diameter section 201 for collecting falling dust. A third dust discharge pipe 306 communicates with the dust collection trough 305 to discharge the dust from the trough. For example, as... Figure 1 , Figure 4 As shown, the guide section 202 can be connected to the reduced diameter section 201 via the first fixing rod 208, and the turbulence section 203 can be connected to the reduced diameter section 201 via the second fixing rod 209 (e.g., Figure 1 (as shown) or ash collection trough 305 (as shown) Figure 4 (As shown above).

[0044] Furthermore, such as Figure 4 As shown, the cross-sectional area of ​​the ash collection trough 305 is larger than the cross-sectional area of ​​the ash discharge channel 303.

[0045] Furthermore, such as Figure 1 , Figure 4 As shown, the static mixing component 200 has an inclined pipe 205 at its lower part. The first row of ash pipes 204, the second row of ash pipes 301, and the third row of ash pipes 306 are all connected to the inclined pipe 205, through which dust is discharged from the flue 100. It should be noted that the portion of the inclined pipe 205 outside the flue 100 can be connected to a straight pipe section and other dust collection equipment, and is equipped with a valve 206 to achieve timed or continuous dust discharge. This is a conventional setting and will not be described in detail here.

[0046] Furthermore, the upper and lower end faces of the reduced diameter section 201 can be circular, elliptical, square, rectangular, or polygonal in shape. For example, see attached... Figures 1-2 The upper and lower ends of the reduced diameter section 201 shown are both rectangular. Figure 4 -Appendix Figure 5 The upper end face of the reduced diameter section 201 shown is circular and the lower end face is square, but the present invention is not limited thereto.

[0047] Furthermore, such as Figure 1 , Figure 4 As shown, the lower end face of the guide section 202 is lower than the upper end face of the narrowing section 201, which is used to guide the flue gas to flow obliquely downward.

[0048] Furthermore, in the above technical solution, the turbulence section 203 is preferably hemispherical, semi-ellipsoidal, or inverted conical (e.g., Figure 4 As shown), inverted quadrangular pyramid (such as...) Figure 1 (as shown), one or more of the following structures: wine glass-shaped, petal-shaped, etc.

[0049] Furthermore, such as Figure 4 As shown, a wind baffle 304 is provided above the groove 300. Preferably, the wind baffle 304 is a straight plate or arc-shaped plate that is connected to the diameter reduction section 201 and tilts downward.

[0050] The dust removal mechanism of the static mixing component 200 of the present invention is as follows: Flue gas flowing through the turbulence section 203 forms a vortex on its back and collides with it. Simultaneously, the flue gas collides with the inner wall surface 202B of the narrowing section 201, causing some dust particles to fall into the turbulence section 203 and exit the flue duct 100 through the first ash pipe 204 and inclined pipe 205, achieving the first separation of dust and flue gas. As the flue gas flows through the narrowing section 201, the flow area gradually decreases, and the flow velocity increases, increasing the probability of dust collisions in the flue gas. Some of the dust particles agglomerate into larger particles, which are more easily removed from the flue gas. During this process, some dust particles fall into the turbulence section 203 under their own gravity or after colliding with the inner wall surface 202B of the narrowing section 201, thus achieving the second removal of dust. The flue gas then leaves the narrowing section 201. As the flue gas flows through the channel formed by the guide section 202 and the narrowing section 201, the flow direction changes from upward to downward. Some of the dust in the flue gas enters the groove 300 or enters the ash collection tank 305 through the ash discharge channel 303 under the action of inertial force and its own gravity. The flue gas collides with the adjacent flue gas leaving the static mixing component 200. After the collision between dust particles with similar particle sizes, the horizontal forces cancel each other out, and the vertical forces are superimposed to accelerate the dust particles into the groove 300 or into the ash collection tank 305 through the ash discharge channel 303, thereby achieving rapid separation of dust and flue gas and increasing the dust removal rate and removal efficiency. The dust particles that enter the groove 300 or enter the ash collection tank 305 through the ash discharge channel 303 are discharged from the flue 100 through the second ash discharge pipe 301 or the third ash discharge pipe 306 and the inclined pipe 205, thereby achieving the third dust removal.

[0051] According to a second aspect of the present invention, the present invention provides a flue gas denitrification ammonia injection mixing system, which includes, in sequence along the flue gas flow direction: an ammonia injection assembly 400, including an ammonia nozzle 401, an ammonia injection branch pipe 402 and an ammonia injection main pipe 403, wherein the ammonia nozzle 401 is connected to the ammonia injection main pipe 403 through the ammonia injection branch pipe 402; and a static mixer as described in any of the above technical solutions, wherein the static mixing assembly 200 is disposed corresponding to the ammonia nozzle 401.

[0052] Furthermore, such as Figures 1-5 As shown, each static mixing component 200 corresponds to the same number of ammonia nozzles 401.

[0053] Furthermore, such as Figure 1 , Figure 4 As shown, the ammonia nozzle 401 corresponds one-to-one with the guide section 202 of the static mixing component 200 and is located directly below the turbulence section 203.

[0054] The ammonia mixing mechanism of the present invention is as follows: The ammonia nozzle 401 is positioned directly below the guide section 202 of the static mixing assembly 200. After being ejected from the ammonia nozzle 401, the ammonia encounters the turbulence section 203, transforming from a single stream of ammonia into a stream surrounding the turbulence section 203, thus increasing the dispersion of ammonia in the flue gas. When the static mixing assembly 200 is equipped with multiple turbulence sections 203, it is even more beneficial for the dispersion of ammonia in the flue gas. When the flue gas and ammonia flow through the area between the turbulence section 203 and the narrowing section 201, the flue gas flow area decreases, the gas velocity increases, and the collision and mixing between the flue gas and ammonia, as well as between the flue gas and the narrowing section 201, intensifies, enhancing the mixing of ammonia and flue gas. After passing through the turbulence section 203, the gas forms a vortex and collides after the turbulence section 203, further enhancing the mixing. The mixing of ammonia and flue gas: After being turbulent, the flow area of ​​the flue gas gradually decreases again during its flow within the narrowing section 201, and the gas velocity increases. The collision and mixing between the flue gas and ammonia, as well as between the flue gas and the narrowing section 201, intensifies, thus strengthening the mixing of ammonia and flue gas. After leaving the narrowing section 201, the gas collides with the guide section 202, and the gas flow direction changes. During this process, the collision with the vessel wall and the change in flow direction further enhance the mixing of ammonia and flue gas. The gas leaves the static mixing component 200 through the channel between the narrowing section 201 and the guide section 202, and collides with the flue gas of the adjacent static mixing component 200. The two mixed flue gas streams are forcibly mixed, which effectively enhances the mixing effect of flue gas and ammonia, improves the uniformity of gas mixing, and thus shortens the distance required for uniform mixing.

[0055] The present invention will now be described in more detail by way of specific embodiments. It should be understood that the present invention is not limited thereto.

[0056] Example 1

[0057] refer to Figures 1-3As shown, the static mixer in this embodiment is a single layer, comprising eight static mixing components 200. Each static mixing component 200 consists of a narrowing section 201, a guide section 202, a turbulence section 203, and a first ash discharge pipe 204. The upper and lower surfaces of the narrowing section 201 are rectangular. The guide section 202 is located directly above the narrowing section 201 and is a quadrangular pyramid. Its four sides are parallel to the four sides of the narrowing section 201 and are connected to the narrowing section 201 via a first fixing rod 208. Its lower surface is lower than the upper surface of the narrowing section 201, thereby allowing the flue gas to flow obliquely downward through the channel between the guide section 202 and the narrowing section 201. A turbulence section 203 is provided in the lower part of the narrowing section 201. The turbulence section 203 is an inverted quadrangular pyramid structure, and the four sides of its upper surface are parallel to the corresponding sides of the narrowing section 201. Two adjacent static mixing components 200 are sealed together to form a groove 300. A ash discharge hole 302 is provided in the groove 300. The lower end of the ash discharge hole 302 is connected to a second ash discharge pipe 301. Both the first ash discharge pipe 204 and the second ash discharge pipe 301 are connected to the inclined pipe 205. The dust is discharged from the flue 100 through the inclined pipe 205.

[0058] The lower part of the static mixer is provided with an ammonia injection assembly 400, which includes an ammonia nozzle 401, an ammonia injection branch pipe 402 and an ammonia injection main pipe 403. The ammonia nozzle 401 is connected to the ammonia injection main pipe 403 through the ammonia injection branch pipe 402. Each ammonia nozzle 401 corresponds to a static mixing assembly 200 and is located directly below the turbulence section 203 of the static mixing assembly 200.

[0059] The flue gas from a coal-fired boiler, using the ammonia injection mixing system and static mixer of this embodiment, has a particulate matter (dust) content of 2546 mg / Nm³ before the static mixer along the flue gas flow direction. 3 The particulate matter (dust) content after the static mixer is 1828 mg / Nm³. 3 The dust removal efficiency was 28.2%; at 500mm before the inlet of the first catalyst layer of the SCR reactor, the NH3 / NO content at various points in the flue gas across 100% of the flue cross-section was... x The deviation of the molar ratio is 9.1%, which meets the requirements of the "Technical Guidelines for Flue Gas Denitrification in Thermal Power Plants" (DL / T 296-2011).

[0060] Example 2

[0061] refer to Figures 4-5As shown, the difference between this embodiment and Embodiment 1 is that the static mixer in this embodiment includes 16 static mixing components 200. The upper end face of the narrowing section 201 is circular, and the lower end face is rectangular. The guide section 202 is frustum-shaped, and the turbulence section 203 is inverted cone-shaped. A baffle plate 304 is provided above the groove 300, which is connected to the narrowing section 201 and inclined downward. A certain gap is provided between two adjacent static mixing components 200 as a dust discharge channel 303. The lower part of the dust discharge channel 303 is connected to a dust collection trough 305, and the third dust discharge pipe 306 is connected to the dust collection trough 305 and the inclined pipe 205. The rest is the same as in Embodiment 1.

[0062] The flue gas from a coal-fired boiler, using the ammonia injection mixing system and static mixer of this embodiment, has a particulate matter (dust) content of 5120 mg / Nm³ before the static mixer along the flue gas flow direction. 3 The particulate matter (dust) content after the static mixer is 3325 mg / Nm³. 3 The dust removal efficiency was 35.1%; at 500mm before the inlet of the first catalyst layer of the SCR reactor, the NH3 / NO content at various points in the flue gas across 100% of the flue cross-section was... x The deviation of the molar ratio is 8.5%, which meets the requirements of the "Technical Guidelines for Flue Gas Denitrification in Thermal Power Plants" (DL / T 296-2011).

Claims

1. A static mixer, characterized in that: The static mixer is a single or multi-layered unit installed in a flue, comprising: multiple static mixing components arranged side by side; each static mixing component includes: a narrowing section, which is a hollow tubular structure with an upper opening area smaller than the lower opening area; a guide section, located above the narrowing section, which is an inverted concave structure used to guide the flue gas leaving the narrowing section to collide with the flue gas leaving adjacent static mixing components; at least one turbulence section, which is a concave hollow structure with an upper opening, located below or inside the narrowing section, the bottom of which is connected to a first row of ash pipes; a first row of ash pipes used to discharge dust from the turbulence section into the flue; a groove, formed by a sealed connection between two adjacent static mixing components, used to collect falling dust; a second row of ash pipes, connected to the groove through ash discharge holes, used to discharge dust from the groove; the lower end of the guide section is lower than the upper end of the narrowing section, used to guide the flue gas to flow obliquely downwards; the turbulence section is one or more of the following structures: hemispherical, semi-ellipsoidal, inverted conical, inverted quadrangular pyramidal, and petal-shaped.

2. The static mixer according to claim 1, characterized in that: A certain gap is provided between two adjacent static mixing components as a dust discharge channel. The lower part of the dust discharge channel is connected to a dust collection trough, which is sealed to the reduced diameter section to collect the falling dust. The third dust discharge pipe is connected to the dust collection trough to discharge the dust in the dust collection trough.

3. The static mixer according to claim 1, characterized in that: The static mixing component is equipped with an inclined tube at the bottom. The first and second rows of ash pipes are connected to the inclined tube, and the dust is discharged from the flue through the inclined tube.

4. The static mixer according to claim 2, characterized in that: The cross-sectional area of ​​the ash collection trough is larger than that of the ash discharge channel.

5. The static mixer according to claim 2, characterized in that: The static mixing component is equipped with an inclined tube at the bottom, and the third row of ash pipes is connected to the inclined tube, through which the dust is discharged from the flue.

6. The static mixer according to claim 1, characterized in that: A wind deflector is installed above the groove.

7. The static mixer according to claim 6, characterized in that: The wind deflector is a straight or curved plate that is connected to the reduced diameter section and tilted downwards.

8. A flue gas denitrification ammonia injection mixing system, characterized in that... The system comprises, in sequence along the flue gas flow direction: an ammonia injection assembly, including an ammonia nozzle, an ammonia injection branch pipe, and an ammonia injection main pipe, wherein the ammonia nozzle is connected to the ammonia injection main pipe through the ammonia injection branch pipe; and a static mixer as described in any one of claims 1 to 7, wherein a static mixing component within the static mixer is correspondingly arranged to the ammonia nozzle.

9. The flue gas denitrification ammonia injection mixing system according to claim 8, characterized in that: Each static mixing component corresponds to the same number of ammonia nozzles.

10. The flue gas denitrification ammonia injection mixing system according to claim 8, characterized in that: The ammonia nozzles correspond one-to-one with the flow guide sections of the static mixing assembly and are located directly below the turbulence section.

Images