A static mixer

Abstract

The present invention relates to a static mixer, comprising at least one mixing unit, the mixing unit comprising a plurality of mixing elements, the mixing element comprising a first plate body and a second plate body, one side of the first plate body and the second plate body being connected so as to form an angle of 0 to 180 degrees therebetween, the mixing element comprising a first mixing element and a second mixing element located on one side, a third mixing element and a fourth mixing element located on the other side, the first mixing element and the second mixing element being parallel and forming a first channel therebetween, the third mixing element and the fourth mixing element being parallel and forming a second channel therebetween, the extension directions of the first channel and the second channel forming an angle of 0 to 180 degrees in space. The present invention can make the NO at the inlet of the ammonia injection grid x The relative standard deviation of concentration distribution is greatly reduced, the weight is lighter under the same resistance, and the resistance is smaller under the same weight. The structure with side openings and sloped surfaces prevents serious dust accumulation inside the mixer from the root.

Description

Technical Field

[0001] The invention belongs to the fields of flue gas denitration and chemical industry, and particularly relates to a static mixer. Background Art

[0002] To meet NO x Ultra-low emissions, coal-fired power plants NO x Emissions should be reduced to 50mg / m 3 Below, the SCR denitrification efficiency needs to be increased to about 90%. In order to control the ammonia escape concentration and ensure the safe operation of the unit, it is necessary not only to increase the volume of catalyst, but also to adjust the NH3 / NO x The uniformity of molar ratio distribution also puts forward higher requirements. x The concentration and distribution are directly related to the combustion conditions in the furnace. Changes in the combustion conditions in the furnace caused by unit load, grinding combination changes and combustion adjustments will lead to NO in the SCR inlet. x The concentration distribution changes significantly, and the NH3 / NO x The uniformity of the molar ratio distribution deteriorates, and the ammonia escape at the denitrification outlet increases.

[0003] To improve the NH3 / NO ratio at the inlet of SCR catalyst x To improve the uniformity of molar ratio distribution, AIG nozzles and static mixers are usually arranged in an array at the SCR inlet section to enhance the mixing of the reducing agent ammonia and the flue gas at the nozzle outlet. These SCR static mixers have a small mixing range (≤3m) and can only adapt to the NO in the upstream flue gas by adjusting the AIG branch flow rate. x Changes in concentration field and flow field. When the unit has different loads and coal mill combinations, the NO x When the concentration distribution changes greatly, the conventional ammonia injection mixing device cannot adapt to the working conditions, and the NH3 / NO x Mixing uniformity deteriorates.

[0004] For example, Chinese patent document CN106731827A discloses a large-scale self-mixing device for flue gas upstream of AIG. The device has a diamond-shaped partition in the middle of the inlet, and straight plates or folded plates are used on both sides to guide the flow. The outlet is not provided with a flow bypass element. Due to the limitations of the inlet and outlet structure of the device, only NO at the inlet of the ammonia injection grid can be mixed. x The relative standard deviation of the concentration distribution decreased by 20% to 40%, and the performance needs to be further improved. Chinese patent document CN112717683A discloses a triangular multi-channel SCR static mixer, which makes the NO xThe relative standard deviation of the concentration distribution decreased by over 60%, but the device was large in size and weight, limiting its use to SCR denitrification systems with long vertical flues. Chinese patent document CN100339154C discloses a static mixer for low-viscosity fluids. This cross-channel static mixer, constructed of corrugated plates, is compact and lightweight, offering flexible layout. However, when used in the horizontal flue at the SCR inlet, there is a risk of dust accumulation within the channel.

[0005] It is necessary to develop a new type of SCR static mixer to reduce the impact of unit load, grinding combination and combustion adjustment on SCR inlet NO x The influence of concentration distribution can fundamentally improve the adaptability of the SCR denitrification device to operating conditions and reduce ammonia slip.

[0006] SCR: Selective Catalytic Reduction, referred to as SCR. SCR denitrification technology refers to the process in which a reducing agent (such as liquid ammonia, urea, and ammonia water, etc.) reacts with NOx in the flue gas under the action of a catalyst in the temperature range of 280~420℃ to produce pollution-free N2 and H2O. x Emission reduction technology.

[0007] AIG: Ammonia Injection Grid, referred to as AIG, is a device that sprays reducing agent evenly into the flue gas.

[0008] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0009] The purpose of the present invention is to provide a static mixer that can be used for mixing flue gas at the inlet of SCR denitrification. The weight, resistance and mixing effect are greatly improved compared with the existing technology, and the risk of dust accumulation in the channel can be eliminated. It can also be used for mixing various fluids in the chemical industry.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A static mixer comprises at least one mixing unit, one end of the mixing unit forming an inlet end and the other end forming an outlet end, the mixing unit comprising a plurality of mixing elements, the mixing element comprising a first plate body and a second plate body, one side of the first plate body and the second plate body being connected so that an angle greater than 0° and less than 180° is formed between the first plate body and the second plate body, the mixing element comprising a first mixing element and a second mixing element located on one side, and a third mixing element and a fourth mixing element located on the other side, the first mixing element and the second mixing element being arranged in parallel and forming a first channel for medium flow therebetween, the third mixing element and the fourth mixing element being arranged in parallel and forming a second channel for medium flow therebetween, the extension directions of the first channel and the second channel forming an angle greater than 0° and less than 180° in space, one end of the first channel and the second channel being the inlet end, and the other end of the first channel and the second channel being the outlet end.

[0012] Preferably, the openings of the angle formed between the first plate body and the second plate body in the first mixing element and the second mixing element are oriented in the same direction, and the opening of the angle formed between the first plate body and the second plate body in the second mixing element is oriented toward the first mixing element; the openings of the angle formed between the first plate body and the second plate body in the third mixing element and the fourth mixing element are oriented in the same direction, and the opening of the angle formed between the first plate body and the second plate body in the third mixing element is oriented toward the fourth mixing element.

[0013] Further preferably, the openings of the angle formed between the first plate and the second plate in the first and fourth mixing elements face away from each other, and the openings of the angle formed between the first plate and the second plate in the second and third mixing elements face toward each other.

[0014] Preferably, projections of the first channel and the second channel on the inlet end of the mixing unit are parallel to each other.

[0015] Preferably, the angle formed between the first plate and the second plate is 60-120°.

[0016] Preferably, the spatial included angle between the extension directions of the first channel and the second channel is 60-150°.

[0017] Preferably, the first mixing element, the second mixing element, the third mixing element and the fourth mixing element have the same shape.

[0018] Preferably, the first plate body and the second plate body of the same mixing element have the same shape and are symmetrically arranged, and the first plate body and the second plate body are parallelogram or trapezoidal.

[0019] Preferably, in the same mixing unit, the first mixing element is connected to the third mixing element, and the second mixing element is connected to the fourth mixing element.

[0020] Further preferably, in the same mixing unit, one end of the first mixing element is connected to one end of the fourth mixing element.

[0021] Further preferably, the distance between the first mixing element and the second mixing element at one end of the first channel is L, the distance between the third mixing element and the fourth mixing element at one end of the second channel is L, and the shortest distance between the second mixing element at the other end of the first channel and the third mixing element at the other end of the second channel is d, where d=0.1~0.5L.

[0022] Preferably, when the static mixer is provided with a plurality of the mixing units, the inlet ends of the plurality of the mixing units are located on the same plane, one end of the first mixing element in one of the mixing units is connected to one end of the fourth mixing unit in the adjacent mixing unit, the first mixing element in one of the mixing units is connected to the third mixing unit in the adjacent mixing unit, one end of the second mixing element in one of the mixing units is connected to one end of the third mixing unit in the adjacent mixing unit, and the second mixing element in one of the mixing units is connected to the fourth mixing unit in the adjacent mixing unit.

[0023] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0024] The present invention can make the NO inlet of the ammonia injection grid x The relative standard deviation of concentration distribution is greatly reduced, the structure is simple, easy to manufacture, saving consumption of production materials, lighter weight under the same resistance, and smaller resistance under the same weight. When set in the flue, it has a side opening and a sloped surface structure, which prevents serious dust accumulation inside the mixer from the root. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attachment Figure 1 Schematic diagram of the structure of the mixing unit in this embodiment;

[0026] Attachment Figure 2 Schematic diagram of the structure of the static mixer in this embodiment;

[0027] Attachment Figure 3 This is a front view of the static mixer in this embodiment arranged in the flue;

[0028] Attachment Figure 4 This is a top view of the static mixer disposed in the flue in this embodiment;

[0029] Attachment Figure 5 This is a front view illustrating the flue gas flow lines when the static mixer is arranged in the flue in this embodiment;

[0030] Attachment Figure 6 This is a top view illustrating the flue gas flow lines when the static mixer is arranged in the flue in this embodiment;

[0031] Attachment Figure 7 NO when the static mixer is set in the flue in this embodiment x Schematic diagram of CFD simulation results of mixing effects.

[0032] In the above figures: 1, first mixing element; 2, second mixing element; 3, third mixing element; 4, fourth mixing element; 5, first plate; 6, second plate. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on 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.

[0035] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0036] like Figure 1 、 2As shown, a static mixer includes a mixing unit. The flue gas can be mixed by one mixing unit or by multiple mixing units connected to each other. One end of the mixing unit forms an inlet end and the other end forms an outlet end. The inlet end and the outlet end of the mixing unit are arranged along the flow direction of the flue gas.

[0037] like Figure 1 As shown, the mixing unit includes a plurality of mixing elements, and the shapes of the plurality of mixing elements are the same. Each mixing element includes a first plate 5 and a second plate 6. The shapes of the first plate 5 and the second plate 6 are also the same and are parallelograms or trapezoids. One side of the first plate 5 and the second plate 6 are connected so that an angle α greater than 0° and less than 180° is formed between the first plate 5 and the second plate 6, as shown in FIG. Figure 1 As shown, the first and second plates 5, 6 are integrally arranged and assembled into a single, folded plate. The sharp corners and internal folding structure of the mixing element allow the boundary layer of smoke to break off at the two sharp corners and edges at the end of the mixing element, generating vortices and enhancing the mixing effect. Within the same mixing element, the symmetrical arrangement of the first and second plates 5, 6, with an angle between them of 60° and 120°, results in better smoke mixing for mixing elements of the same size.

[0038] The mixing element includes a first mixing element 1 and a second mixing element 2 located on one side of the mixing unit, and a third mixing element 3 and a fourth mixing element 4 located on the other side of the mixing unit. The first mixing element 1 and the second mixing element 2 are arranged in parallel (that is, the first plate 5 and the second plate 6 of the two are parallel) and a first channel for smoke flow is formed therebetween. The third mixing element 3 and the fourth mixing element 4 are arranged in parallel (that is, the first plate 5 and the second plate 6 of the two are parallel) and a second channel for smoke flow is formed therebetween. One end of the first channel and the second channel is the inlet end of the mixing unit, and the other end of the first channel and the second channel is the outlet end of the mixing unit.

[0039] like Figure 1 、 2As shown, the opening direction of the angle formed between the first plate 5 and the second plate 6 in the first mixing element 1 and the second mixing element 2 is the same, and the opening of the angle formed between the first plate 5 and the second plate 6 in the second mixing element 2 is toward the first mixing element 1, and the first mixing element 1 and the second mixing element 2 are arranged along the direction of their opening. The opening direction of the angle formed between the first plate 5 and the second plate 6 in the third mixing element 3 and the fourth mixing element 4 is the same, and the opening of the angle formed between the first plate 5 and the second plate 6 in the third mixing element 3 is toward the fourth mixing element 4, and the third mixing element 3 and the fourth mixing element 4 are arranged along the direction of their opening. In the same mixing unit, the opening direction of the angle formed between the first plate 5 and the second plate 6 in the first mixing element 1 and the fourth mixing element 4 is opposite to each other, and the opening direction of the angle formed between the first plate 5 and the second plate 6 in the second mixing element 2 and the third mixing element 3 is opposite to each other.

[0040] In the flue, the first mixing element 1 and the second mixing element 2, as well as the third mixing element 3 and the fourth mixing element 4, are arranged along the length of the flue. However, the openings of the first mixing element 1 and the second mixing element 2 are oriented in opposite directions from those of the third mixing element 3 and the fourth mixing element 4. Furthermore, the first mixing element 1 and the fourth mixing element 4 are arranged diagonally, while the second mixing element 2 and the third mixing element 3 are arranged diagonally. Within the same mixing unit, the first mixing element 1 is connected to the third mixing element 3, and the second mixing element 2 is connected to the fourth mixing element 4, forming a support structure that stabilizes the static mixer. One end of the first mixing element 1 is connected to one end of the fourth mixing element 4 (i.e., at the inlet end of the mixing unit), facilitating the installation and positioning of the static mixer. This modular matrix structure promotes stable and uniform flue gas flow, facilitating mixing.

[0041] The extension directions of the first channel and the second channel form an angle β in space that is greater than 0° and less than 180°, such as Figure 3 As shown, at the same time, the projections of the first channel and the second channel on the inlet end of the mixing unit are parallel to each other. This is equivalent to the first channel and the second channel being arranged crosswise and not completely parallel in space, but at the same time, the space where the extension range of the first channel is located is parallel to the space where the extension range of the second channel is located, and there will be no intersection or overlap. Figure 1 This mixing unit structure, with its side openings and sloped surface in the direction of flue gas flow, fundamentally prevents severe dust accumulation within the mixer. When the spatial angle between the first and second channels is 60-150°, the flue gas mixing is optimal for mixing elements of the same size, achieving both vortex mixing and avoiding excessive resistance.

[0042] The distance between the first mixing element 1 and the second mixing element 2 at one end of the first channel is L, and the distance between the third mixing element 3 and the fourth mixing element 4 at one end of the second channel is also L. Figure 2 、 3 , 4, that is, the opening width of the first channel and the second channel at the inlet end of the mixing unit is L, and the shortest distance between the second mixing element 2 at the other end of the first channel and the third mixing element 3 at the other end of the second channel is d, as shown in FIG. Figure 2 、 3 , 4, and when d = 0.1 ~ 0.5L, in the flue gas flow direction, the inlet end of the mixing unit can be observed from the outlet end of the mixing unit without being blocked by the mixing element, as shown in FIG. Figure 4 As shown, a certain distance d is retained at the other end of the second mixing element 2 and the third mixing element 3 to reduce the resistance of the smoke flow out. By limiting the length ratio of d and L, the length of the mixing element is prevented from being too long and causing excessive resistance.

[0043] like Figure 3 、 4 As shown, when a static mixer is provided with multiple mixing units, the inlet ends of the multiple mixing units are located on the same plane and together constitute the inlet of the static mixer, the outlet ends of the multiple mixing units are located on the same plane and together constitute the outlet of the static mixer, one end of the first mixing element 1 in a mixing unit is connected to one end of the fourth mixing element 4 in an adjacent mixing unit (i.e., at the inlet of the mixing unit), the first mixing element 1 in a mixing unit is connected to the third mixing element 3 in an adjacent mixing unit (i.e., the sides of their respective plates are connected), one end of the second mixing element 2 in a mixing unit is connected to one end of the third mixing element 3 in an adjacent mixing unit (i.e., at the inlet of the mixing unit), and the second mixing element 2 in a mixing unit is connected to the fourth mixing element 4 in an adjacent mixing unit (i.e., the sides of their respective plates are connected), forming a matrix structure. In the length direction of the flue, the multiple mixing units are arranged in parallel with equal spacing (L), and the multiple mixing elements are also arranged in parallel with equal spacing (L). In the width direction of the flue, the mixing units are connected in parallel, and the projections of the adjacent first channels and second channels of adjacent mixing units on the inlet end of the static mixer are parallel to each other. In the width direction of the flue, the more mixing units are provided, the worse the mixing effect is.

[0044] The specific application of this embodiment and the comparison with the prior art are given below:

[0045] In a section of SCR inlet flue with a cross-sectional size of 15m×3m, the following Figure 2 The static mixer shown in FIG. Figure 3 、 4The structure shown. Five groups of mixing units are set in the length direction of the flue, and two groups of mixing units are set in the width direction of the flue. The first mixing element 1 and the third mixing element 3 are perpendicularly crossed at 90 degrees, the second mixing element 2 and the fourth mixing element 4 are perpendicularly crossed at 90 degrees, the first plate 5 and the second plate 6 of the mixing element are parallelograms and the angle between them is 90 degrees, L=1.5m, d=0.7m, along the direction of flue gas flow, the static mixer is 1.1m high. The average flue gas flow rate is 15m / s. For the SCR inlet NO x The distribution is bad with one side high and the other side low.

[0046] After the static mixer of this embodiment is installed, NO x The relative standard deviation (CV value) of the concentration distribution decreased from 50% to 21% after a mixing distance of 10m, and from 50% to 18% after a mixing distance of 15m. Figure 7 As shown. The triangular multi-channel SCR static mixer disclosed in Chinese patent document CN112717683A, NO x The relative standard deviation (CV value) of the concentration distribution is reduced from 50% to 24% after a mixing distance of 10m, and from 50% to 18% after a mixing distance of 10m. The static mixer for low viscosity fluid disclosed in Chinese patent document CN100339154 C adopts a corrugated plate static mixer, NO x The relative standard deviation (CV value) of the concentration distribution decreased from 50% to 23% after a mixing distance of 10 m, and from 50% to 21% after a mixing distance of 15 m.

[0047] A comparison of the sizes and performance indicators of the three mixers is shown in Table 1. Compared with the triangular multi-channel SCR static mixer disclosed in Chinese patent document CN112717683A, the static mixer of this embodiment has absolute advantages in weight and size, and has better short-distance mixing effect. Compared with the static mixer for low-viscosity fluids disclosed in Chinese patent document CN100339154C, which uses a corrugated plate static mixer, the static mixer of this embodiment has better weight, mixing effect, and resistance. In addition, the structural design of the side openings and sloped surfaces of the mixing element in this embodiment fundamentally prevents serious dust accumulation inside the static mixer.

[0048] Table 1 is a comparison of the mixing effects of this embodiment and Chinese patent documents CN112717683A and CN100339154C:

[0049]

[0050] The mixing principle of the static mixer in this embodiment is:

[0051] In the length direction of the flue, multiple mixing units are arranged at equal intervals (L), and a flue gas channel is formed between two adjacent mixing elements. The streamlines of the flue gas passing through the mixing are as follows: Figure 5 and Figure 6 As shown. In the width direction of the flue, the first mixing element 1 and the third mixing element 3 appear in pairs, and the second mixing element 2 and the fourth mixing element 4 appear in pairs. This arrangement divides the incoming flue gas into an even number of layers in the width direction of the flue, one layer flowing to the left and one layer flowing to the right. Under the action of the mixing elements, the flue gas is divided and transferred. After the flue gas is transferred to the left by a certain channel, the air pressure on the right side of the channel decreases. After the flue gas is transferred to the right by a certain channel, the air pressure on the left side of the channel decreases. Therefore, a vortex is formed in a mixing unit. However, at the same time, the flow direction of the flue gas is consistent in each layer, which will lead to the overall transfer of the flue gas, thereby realizing a large-scale transfer and cross-mixing of the airflow, as shown in FIG. Figure 5 As shown in the figure, the cross-flow at the downstream of the static mixer rotates while flowing forward, presenting a group of rotating vortices, forming a large vortex mixing, as shown in the figure. Figure 6 At the microscopic level, the boundary layer of the airflow sheds at the two sharp corners and sharp edges at the end of the mixing element, generating vortices and further increasing the mixing effect.

[0052] The static mixer in this embodiment is not limited to use in the SCR denitrification field, but can also be used for fluid mixing in the chemical industry. Its mixing principle is the same as above, and the mixed flow state of the fluid is the same as the mixed flow state of the above-mentioned flue gas.

[0053] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0054] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A static mixer, characterized in that: The invention comprises at least one mixing unit, wherein one end of the mixing unit forms an inlet end and the other end forms an outlet end, the mixing unit comprises a plurality of mixing elements, the mixing element comprises a first plate body and a second plate body, one side of the first plate body and the second plate body are connected so that an angle greater than 0° and less than 180° is formed between the first plate body and the second plate body, the mixing element comprises a first mixing element and a second mixing element located on one side, and a third mixing element and a fourth mixing element located on the other side, in the same mixing unit, the first mixing element is connected to the third mixing element, the second mixing element is connected to the fourth mixing element, one end of the first mixing element is connected to one end of the fourth mixing element, and the first mixing element and the second mixing element are parallel to each other. The first and second mixing elements are arranged in parallel and form a first channel for medium flow therebetween. The third and fourth mixing elements are arranged in parallel and form a second channel for medium flow therebetween. The angle between the extension directions of the first and second channels in space is 60-150°. One end of the first and second channels is the inlet end, and the other end of the first and second channels is the outlet end. The distance between the first and second mixing elements at one end of the first channel is L, the distance between the third and fourth mixing elements at one end of the second channel is L, and the shortest distance between the second mixing element at the other end of the first channel and the third mixing element at the other end of the second channel is d, where d=0.1-0.5L.

2. The static mixer according to claim 1, characterized in that: The openings of the angle formed between the first plate and the second plate in the first and second mixing elements are oriented in the same direction, and the opening of the angle formed between the first plate and the second plate in the second mixing element is oriented toward the first mixing element. The openings of the angle formed between the first plate and the second plate in the third and fourth mixing elements are oriented in the same direction, and the opening of the angle formed between the first plate and the second plate in the third mixing element is oriented toward the fourth mixing element.

3. The static mixer according to claim 2, characterized in that: The openings of the angle formed between the first plate and the second plate in the first and fourth mixing elements face away from each other, and the openings of the angle formed between the first plate and the second plate in the second and third mixing elements face toward each other.

4. The static mixer according to claim 1, wherein: The angle formed between the first plate and the second plate is 60-120°.

5. The static mixer according to claim 1, characterized in that: The first mixing element, the second mixing element, the third mixing element and the fourth mixing element have the same shape.

6. The static mixer according to claim 1, characterized in that: The first plate body and the second plate body of the same mixing element have the same shape and are symmetrically arranged. The first plate body and the second plate body are parallelogram or trapezoidal.

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