Scr reactor combined rectifier

Abstract

This invention discloses a combined rectifying device for an SCR reactor. The device includes: an arc-shaped guide plate installed within the bend of the reactor inlet duct for pre-rectifying the airflow from the upstream bend; and an inlet grille, multiple layers of staggered angle steel, a middle grille, a perforated plate, and a lower grille arranged sequentially from top to bottom at the inlet diameter change of the SCR reactor. The inlet grille guides the airflow to diffuse in all directions; the multiple layers of staggered angle steel cut off and disperse the airflow to the four corners of the reactor; the middle grille guides the airflow to the short side of the reactor; the perforated plate further disperses and homogenizes the airflow; and the lower grille organizes the airflow into a uniform, vertically downward, stable airflow. This device, through five stages of progressive dispersion rectification, reduces the airflow velocity dispersion coefficient (Cv) on the catalyst surface to below 0.15, significantly improving airflow uniformity and catalyst utilization. It is suitable for SCR systems with complex spatial layouts, such as C1 cyclone intake ducts in the cement industry.

Description

Technical Field

[0001] This invention relates to a combined SCR reactor rectifier device. Background Technology

[0002] Selective catalytic reduction (SCR) technology is currently the mainstream technology for industrial flue gas denitrification. It involves injecting reducing agents such as ammonia or urea into the flue gas, where nitrogen oxides (NOx) are selectively reduced to harmless nitrogen and water under the action of a catalyst. This technology has advantages such as high denitrification efficiency and stable operation, and is widely used in flue gas treatment in industries such as power, cement, and steel.

[0003] In SCR systems, when flue gas is introduced into the reactor from the flue, the airflow distribution is extremely uneven due to bends and diameter changes in the intake duct. The catalyst layer area inside the reactor is typically about six times the cross-sectional area of ​​the inlet duct; this significant area difference exacerbates the uneven airflow. Uneven airflow distribution leads to excessive local reaction load on the catalyst, accelerated wear, and partial catalyst failure due to lack of contact with the reducing agent. This results in reduced overall denitrification efficiency and increased ammonia slip. To maintain denitrification performance, it is necessary to increase the catalyst dosage, significantly increasing investment and operating costs.

[0004] To address the aforementioned issues, existing technologies typically employ multiple annular guide vanes at the inlet of the SCR reactor and a flow rectifying device consisting of two layers of staggered perforated plates at the end. The working principle is as follows: the vertically inlet airflow is gradually diffused outwards by multiple layers of annular guide vanes, which are smaller at the top and larger at the bottom. The initially dispersed airflow then enters the two layers of staggered perforated plates, where the throttling and collision effects of the perforated plates streamline the airflow, ultimately ensuring that the airflow reaches the catalyst surface as uniformly as possible.

[0005] However, the scheme of combining the annular guide plate with the staggered orifice plate has the following technical drawbacks: First, the airflow dispersion effect is limited, and dead zones exist. The airflow after diffusion by the annular guide plate still presents multiple annular distributions, failing to effectively distribute the airflow to the four corners of the reactor, resulting in low catalyst utilization at the reactor's corners.

[0006] Second, it disrupts the airflow direction and affects the stability of the flow field. The staggered orifice plate does not have a sufficient rectifying effect on the airflow, which can cause the airflow direction to tilt, generate a lateral velocity component, and fail to form a stable vertical downward flow field, thus affecting the uniformity of the airflow in the catalyst layer.

[0007] Third, the system has low efficiency and poor economic performance. The aforementioned airflow dispersion defects lead to insufficient overall catalyst utilization. To ensure denitrification efficiency, the catalyst loading must be increased, which directly increases equipment investment costs. This results in a significant economic disadvantage in large-scale applications in industries such as cement.

[0008] Especially in the cement industry, SCR systems typically draw air from the main duct of the C1 cyclone separator. Due to limited space, the flue requires multiple bends, exacerbating the non-uniformity of the airflow at the reactor inlet. Existing rectification technologies struggle to meet the requirements of high efficiency and low resistance. Therefore, there is an urgent need for a new type of rectification device that can effectively overcome these shortcomings, ensuring highly uniform airflow distribution while reducing system pressure drop and catalyst usage. Summary of the Invention

[0009] The present invention provides an SCR reactor combined rectification device to solve the problems existing in the prior art.

[0010] The technical solutions adopted in this invention are as follows: A combined SCR reactor rectifying device is provided, wherein the device is installed in an SCR system, the SCR system comprising an SCR reactor body, a reactor inlet duct, and an SCR reactor inlet, and the device comprises: An arc-shaped baffle plate is installed in the elbow of the inlet duct to ensure that the airflow enters the SCR reactor inlet uniformly; And, from top to bottom, the inlet grid, multi-layer staggered angle steel (5), intermediate grid, perforated plate and lower grid are arranged in sequence at the inlet diameter change of the SCR reactor; The inlet grille is used to guide the vertically downward airflow to diffuse in all directions; The multi-layered staggered angle steel is used to cut off and disperse the airflow and diffuse it to the four corners of the SCR reactor body; The intermediate grille is used to guide the airflow to the side of the reactor; The perforated plate is used to further disperse the already dispersed airflow; The lower grille is used to organize the airflow into a uniform, vertically downward, stable airflow.

[0011] Furthermore, the arc-shaped guide plate of the air duct is a multi-layered arc-shaped plate, which is fixed in layers to the inner wall of the elbow of the reactor inlet air duct, and the inner arc surface of the arc-shaped plate faces the inlet direction.

[0012] Furthermore, the inlet grid is horizontally fixed to the upper part of the variable diameter section of the SCR reactor inlet, and is formed by several horizontal and vertical steel plates fixedly connected to form a grid structure. The horizontal and vertical steel plates are all arranged inclined in all directions to guide the vertically downward airflow into an oblique airflow that diffuses in all directions.

[0013] The mesh size of the imported grille is larger than the spacing between the steel plates of the lower grille.

[0014] Furthermore, the multi-layered staggered angle steel is composed of several angle steels arranged in layers in the vertical direction. Each layer of angle steel includes transverse angle steel and longitudinal angle steel, which are cross-fixed to form a grid structure. The grids of adjacent layers are staggered in the horizontal direction, so that the airflow is cut off and dispersed into multiple fine airflows as it passes through and diffuses to the four corners of the SCR reactor body.

[0015] Furthermore, the intermediate grid is composed of several inclined steel plates, and the spacing between the steel plates is greater than the spacing between the steel plates of the lower grid to form a sparse structure. The intermediate grid is used to guide the airflow to the short side of the reactor.

[0016] Furthermore, the intermediate grid is arranged when the reactor aspect ratio is greater than 1.25.

[0017] Furthermore, the lower grille is formed by several vertical steel plates arranged in parallel intervals, and the spacing between the steel plates is smaller than the spacing between the steel plates of the middle grille to form a dense structure, which sorts the airflow passing through the perforated plate into a uniform, vertically downward, stable airflow.

[0018] The present invention has the following beneficial effects: (1) By combining the pre-rectification of the duct bend with the five-stage progressive dispersion rectification of the reactor inlet, the dispersion coefficient Cv of the airflow velocity on the catalyst surface is reduced from 0.314 in the prior art to 0.089, and the airflow uniformity is significantly improved.

[0019] (2) The inlet grid guides the airflow to diffuse in all directions. The multi-layered staggered angle steel disperses the airflow through a three-dimensional grid structure and forces it to be distributed to the four corner areas of the reactor. Combined with the targeted guidance of the airflow on the short side by the middle grid, the problem that the airflow cannot reach the four corners in the traditional annular guide plate scheme is solved.

[0020] (3) The lower grid adopts a dense vertical steel plate structure, which sorts the airflow after multi-stage dispersion into a stable vertical downward flow field, avoiding the problem of tilted airflow caused by the staggered perforated plates, and ensuring that the airflow passes through the catalyst layer vertically and uniformly.

[0021] (4) The airflow is evenly distributed and the direction is stable throughout the entire cross section, so that all regions of the catalyst can fully participate in the reduction reaction, which solves the problem of local catalyst failure caused by uneven airflow and improves the overall efficiency of the catalyst.

[0022] (5) Under the premise of ensuring airflow uniformity and denitrification efficiency, there is no need to increase the amount of catalyst, which effectively controls the investment cost of catalyst and is especially suitable for large-scale flue gas treatment projects.

[0023] (6) The arc-shaped guide plate of the air duct can eliminate the uneven flow field generated by the upstream bend pipe. The intermediate grid can be flexibly configured according to the length-width ratio of the reactor, so that the device can be adapted to various complex spatial layouts and flow field conditions such as the C1 cyclone air intake pipe in the cement industry. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the SCR reactor combined rectifier device of the present invention.

[0025] Figure 2 This is a structural diagram of the arc-shaped guide vane for the air duct.

[0026] Figure 3 This is a structural diagram of the imported grille.

[0027] Figure 4 This is a structural diagram of multi-layered staggered angle steel.

[0028] Figure 5 This is a structural diagram of the central grille.

[0029] Figure 6 This is a structural diagram of a perforated plate.

[0030] Figure 7 This is a structural diagram of the lower grille.

[0031] Figure 8 : Distribution of airflow velocity field on the surface of catalyst layer in existing SCR reactors.

[0032] This figure is a simulation diagram of the airflow velocity field on the surface of the catalyst layer corresponding to the prior art (annular guide plate + two layers of staggered perforated plates). The velocity unit is [m / s], and the velocity range is 0.00e+00~2.00e+01. It can be observed in the figure that the airflow velocity distribution is uneven and there are obvious velocity difference areas. This corresponds to the technical defect of the prior art where the airflow dispersion coefficient Cv value is 0.314, and provides a benchmark reference for comparing the advantages of the present invention.

[0033] Figure 9 : Distribution diagram of airflow velocity field on the catalyst layer surface of the combined rectifier device of the SCR reactor of this invention.

[0034] This figure is a simulation diagram of the airflow velocity field on the surface of the catalyst layer corresponding to the device of the present invention. The velocity unit and interval are the same. Figure 8 The figure shows a uniform airflow velocity distribution with no obvious velocity difference areas, which intuitively demonstrates the technical effect of this device in reducing the airflow dispersion coefficient Cv value on the catalyst layer surface to 0.089. It clearly compares with existing technologies and verifies the effect of this invention in improving airflow uniformity.

[0035] Figure 10 : A diagram showing the airflow velocity field distribution at the orifice plate of an existing SCR reactor.

[0036] This figure shows the airflow velocity field "above a double-layered staggered perforated plate" in the existing technology, with the velocity unit and interval being the same. Figure 8 As shown in the figure, when the airflow reaches the orifice plate after passing through multiple annular guide plates, there is a clear annular airflow concentration, indicating that the multiple annular guide plates have a poor dispersion effect on the airflow.

[0037] Figure 11 The airflow velocity field distribution diagram on the orifice plate (7 points on the orifice plate) of the combined SCR reactor rectifier device of this invention. This figure focuses on the airflow velocity field at point 7 of the perforated plate, with the velocity unit and interval being the same. Figure 8 As shown in the figure, after the airflow passes through the holes of the perforated plate 7, it is further dispersed into fine airflow streams, and the velocity distribution becomes more uniform, with no obvious airflow accumulation or gaps. This verifies the secondary dispersion function of the perforated plate 7 on the airflow, laying the foundation for the final sorting of the lower grille 8.

[0038] Figure 12 : Existing SCR reactor gas flow streamline diagram This figure is a simulation diagram of the airflow streamlines from the SCR reactor inlet 3 to the SCR reactor body 9. The velocity units and intervals are the same. Figure 8 The airflow in the inlet area remains relatively concentrated, and the airflow is not effectively dispersed to the orifice plate surface. Furthermore, there are concentrated airflow points on both sides of the orifice plate. This is consistent with... Figure 8 The high-speed airflow positions on both sides correspond. After passing through the orifice plate, due to the staggered arrangement of the double-layer orifice plate, the airflow mainly flows downwards at an angle through the catalyst, ultimately resulting in low reactor efficiency.

[0039] Figure 13 Comparison of airflow streamlines in the combined SCR reactor rectifier device of this invention (pathlines-1) The diagram and Figure 12 Both are airflow streamline simulation diagrams, focusing on showing the distribution of airflow across the entire cross-section of the SCR reactor body 9. The streamlines in the diagram cover the four corners and edge areas of the reactor body 9, with no gaps or dead angles in the streamlines. This clearly verifies the functions of the multi-layered staggered angle steel 5 in "diffusing airflow to the four corners of the reactor" and the intermediate grid 6 in "guiding airflow to the short side," further demonstrating the technical advantage of this device in achieving uniform airflow coverage across the entire cross-section of the reactor.

[0040] 1. Reactor inlet duct; 2. Duct arc-shaped baffle; 3. SCR reactor inlet; 4. Inlet grille; 5. Multi-layer staggered angle steel; 6. Intermediate grille; 7. Perforated plate; 8. Lower grille; 9. SCR reactor body; Detailed Implementation

[0041] The invention will now be further described with reference to the accompanying drawings.

[0042] like Figures 1 to 7 As shown, the SCR reactor combined rectification device of the present invention is used for airflow rectification in an SCR system. The SCR system includes a reactor inlet duct 1, an SCR reactor inlet 3, and an SCR reactor body 9. This device achieves airflow homogenization through a two-stage rectification structure, as detailed below: like Figure 2 As shown, the arc-shaped guide plate 2 of the air duct is a multi-layered arc-shaped plate, which is fixed in layers to the inner wall of the elbow of the reactor inlet air duct 1, with the inner arc surface facing the inlet direction. During installation, it is necessary to ensure that each layer of arc-shaped plate is fitted and fixed to the inner wall of the elbow. The number of layers is determined according to the curvature of the elbow of the reactor inlet air duct 1 and the airflow rate. Its core function is to counteract the airflow deviation caused by the bend of the air duct and ensure that the airflow enters the SCR reactor inlet 3 evenly.

[0043] like Figures 3 to 8 As shown, from top to bottom, the following components are installed at the diameter change point of the SCR reactor inlet 3: inlet grid 4, multi-layer staggered angle steel 5, intermediate grid 6, perforated plate 7, and lower grid 8. Each component is horizontally fixed to the inner wall of the SCR reactor inlet 3 to ensure a stable and secure installation. Imported grating 4 is a mesh structure formed by the fixed connection of transverse and longitudinal steel plates (such as...). Figure 3 The horizontally fixed upper part of the variable diameter section of the SCR reactor inlet 3 has horizontal and longitudinal steel plates that are inclined in all directions. The size of the grid holes is larger than the spacing of the steel plates of the lower grid 8, which is used to convert the vertically downward airflow into an oblique airflow that diffuses in all directions.

[0044] Multi-layered staggered angle steel 5 is composed of several angle steels arranged in layers in the vertical direction (e.g.) Figure 4 Each layer of angle steel includes horizontal and vertical angle steel, which are fixed together to form a grid structure. The grids of adjacent layers are staggered in the horizontal direction. During installation, it is necessary to ensure that the intersection angle of each layer of angle steel is consistent, so that the airflow is cut off and dispersed layer by layer and diffused to the four corners of the SCR reactor body 9.

[0045] The central grating 6 is composed of several inclined steel plates (such as...) Figure 5 The spacing between the steel plates is greater than the spacing between the steel plates of the lower grid 8, forming a sparse structure. Installation is only performed when the length-to-width ratio of the SCR reactor body 9 is greater than 1.25. During installation, the steel plates are tilted towards the short side of the reactor to guide the airflow towards the short side and prevent insufficient airflow on the short side.

[0046] The perforated plate 7 is horizontally installed below the intermediate grid 6 (e.g.) Figure 6 Its aperture is set according to the airflow dispersion requirements. Its core function is to further disperse the airflow after it has been dispersed by multiple layers of interlaced angle steel 5 and intermediate grid 6, thereby improving the airflow uniformity.

[0047] The lower grille 8 is formed by several vertical steel plates arranged in parallel intervals (such as...). Figure 7 The spacing between the steel plates is smaller than the spacing between the steel plates of the intermediate grid 6, forming a dense structure. It is horizontally fixed below the perforated plate 7 and above the catalyst layer near the SCR reactor body 9 to guide the airflow direction.

[0048] Airflow rectification process: Combination Figures 8 to 13 The rectification process of this device is shown in the simulation diagram below: Industrial flue gas enters from the reactor inlet duct 1. When it flows through the arc-shaped guide plate 2 at the bend of the duct, the deflected airflow is guided by the multi-layer arc-shaped plate to form a uniform airflow field and smoothly enter the SCR reactor inlet 3.

[0049] The airflow first contacts the inlet grille 4, and under the guidance of the inclined steel plate, it changes from vertical downward to oblique airflow that diffuses in all directions, thus completing the initial dispersion.

[0050] After initial dispersion, the airflow enters the multi-layered staggered angle steel 5, and is cut off layer by layer by the staggered grid of adjacent layers, and is dispersed into multiple fine airflows. At the same time, it diffuses to the four corners of the SCR reactor body 9, eliminating dead airflow angles.

[0051] When the length-to-width ratio of the SCR reactor body 9 is greater than 1.25, the intermediate grid 6 will guide part of the airflow to the short side to ensure uniform airflow coverage across the entire cross-section of the reactor; if the length-to-width ratio is ≤1.25, the installation of the intermediate grid 6 can be omitted, and the airflow will directly enter the perforated plate 7.

[0052] When the airflow passes through the perforated plate 7, it is further dispersed into more uniform fine airflows, and then flows through the lower grille 8. Under the combing effect of the dense vertical steel plates, the tilted or turbulent airflow is corrected into a stable airflow that is vertically downward.

[0053] Finally, a uniform and stable airflow passes vertically through the catalyst layer within the SCR reactor body 9, such as... Figure 8 and Figure 9 The simulation comparison shows that the device corresponds to Figure 9 The dispersion coefficient Cv of the gas flow velocity on the catalyst surface is 0.089, which is much lower than the 0.314 of the prior art, and the gas flow uniformity is significantly improved. Figures 10 to 13 The airflow profile comparison shows that this device has no inclined airflow and the airflow distribution is consistent across the entire cross-section, ensuring that all regions of the catalyst fully participate in the denitrification reaction.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A combined SCR reactor rectifying device, wherein the device is installed in an SCR system, the SCR system comprising an SCR reactor body (9), a reactor inlet duct (1), and an SCR reactor inlet (3), characterized in that: The device includes: An arc-shaped guide plate (2) is installed in the elbow of the inlet duct (1) of the reactor to ensure that the airflow enters the inlet (3) of the SCR reactor evenly. And, from top to bottom, the inlet grid (4), multi-layer staggered angle steel (5), intermediate grid (6), perforated plate (7) and lower grid (8) are arranged in sequence at the diameter change of the SCR reactor inlet (3); The inlet grille (4) is used to guide the vertically downward airflow to diffuse in all directions; The multi-layered staggered angle steel (5) is used to cut off and disperse the airflow and diffuse it to the four corners of the SCR reactor body (9); The intermediate grid (6) is used to guide the airflow to the side of the reactor; The porous plate (7) is used to further disperse the already dispersed airflow; The lower grille (8) is used to organize the airflow into a uniform, vertically downward, stable airflow.

2. The SCR reactor combined rectifier device according to claim 1, characterized in that: The arc-shaped guide plate (2) of the air duct is a multi-layer arc plate, which is fixed in layers to the inner wall of the elbow of the reactor inlet air duct (1), and the inner arc surface of the arc plate faces the inlet direction.

3. The SCR reactor combined rectifier device according to claim 1, characterized in that: The inlet grid (4) is horizontally fixed to the upper part of the variable diameter section of the SCR reactor inlet (3). It is formed by several horizontal and vertical steel plates fixedly connected to form a grid structure. The horizontal and vertical steel plates are arranged inclined in all directions to guide the vertically downward airflow into an oblique airflow that diffuses in all directions.

4. The SCR reactor combined rectifier device according to claim 3, characterized in that: The mesh size of the imported grille (4) is larger than the steel plate spacing of the lower grille (8).

5. The SCR reactor combined rectifier device according to claim 1, characterized in that: The multi-layered staggered angle steel (5) is composed of several angle steels arranged in layers in the vertical direction. Each layer of angle steel includes transverse angle steel and longitudinal angle steel, which are cross-fixed to form a grid structure. The grids of adjacent layers are staggered in the horizontal direction, so that the airflow is cut off and dispersed into multiple fine airflows and diffused to the four corners of the SCR reactor body (9) when it passes through.

6. The SCR reactor combined rectifier device according to claim 1, characterized in that: The intermediate grid (6) is composed of several inclined steel plates, the spacing between the steel plates being greater than the spacing between the steel plates of the lower grid (8) to form a sparse structure, and is used to guide the airflow to the short side of the reactor.

7. The SCR reactor combined rectifier device according to claim 6, characterized in that: The intermediate grid (6) is arranged when the length-to-width ratio of the reactor is greater than 1.

25.

8. The SCR reactor combined rectifier device according to claim 1, characterized in that: The lower grille (8) is formed by several vertical steel plates arranged in parallel intervals. The spacing between the steel plates is smaller than the spacing between the steel plates of the middle grille (6) to form a dense structure, which sorts the airflow through the perforated plate (7) into a uniform vertical downward stable airflow.

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