Precise ammonia injection SCR denitration device based on flow field optimization

Abstract

The utility model relates to the technical field of SCR denitration, and is a precise ammonia spraying SCR denitration device based on flow field optimization, which comprises an SCR denitration reactor, an inlet gas pipe fixedly and communicatively connected to the top inlet of the SCR denitration reactor, an outlet gas pipe fixedly and communicatively connected to the bottom outlet of the SCR denitration reactor, a flue gas rectifier, a first-stage catalyst layer and a second-stage catalyst layer arranged in the SCR denitration reactor in sequence from top to bottom. The utility model is reasonable and compact in structure and convenient to use. The first, second, third and fourth flow guides arranged at the connecting portions of the inlet gas pipe make the optimized flow field fully mix ammonia gas and flue gas, reduce ammonia escape, lower operation cost, help reduce the impact and abrasion of flue gas on the catalysts in the catalyst layers at different stages, and prolong the service life of the catalysts.

Description

Technical Field

[0001] This utility model relates to the field of SCR denitrification technology, and is a precision ammonia injection SCR denitrification device based on flow field optimization. Background Technology

[0002] Currently, nitrogen oxide (NOx) emissions are increasing rapidly, becoming one of the major sources of air pollution. In order to improve air quality and reduce environmental pollution, coal-fired power plants have introduced SCR (Selective Catalytic Reduction) technology to effectively treat nitrogen oxides in flue gas.

[0003] SCR technology reduces nitrogen oxides to harmless nitrogen and water vapor through the action of a catalyst. To ensure the denitrification effect of the SCR system and prevent uneven distribution of nitrogen oxides in the flue gas due to uneven flue gas flow, which would affect the denitrification efficiency, coal-fired power plants have installed guide plates at a certain point in the vertical and horizontal flue ducts at the inlet of the SCR denitrification reactor. However, because the existing guide plates in the inlet flue ducts of the SCR denitrification reactor are installed in a single type, they have failed to effectively guide the flue gas, resulting in uneven flow field distribution and thus low contact area and efficiency of the denitrification reaction. Summary of the Invention

[0004] This invention provides a precision ammonia injection SCR denitrification device based on flow field optimization, which overcomes the shortcomings of the prior art. It can effectively solve the problem that the guide plate in the inlet flue of the SCR denitrification reactor is installed in a single way, which fails to effectively guide the flue gas and results in uneven flow field distribution.

[0005] The technical solution of this utility model is achieved through the following measures: a precision ammonia injection SCR denitrification device based on flow field optimization, including an SCR denitrification reactor, an inlet pipe fixedly connected to the top inlet of the SCR denitrification reactor, an outlet pipe fixedly connected to the bottom outlet of the SCR denitrification reactor, a flue gas rectifier, a primary catalyst layer and a secondary catalyst layer arranged sequentially from top to bottom inside the SCR denitrification reactor, the inlet pipe including a first horizontal pipe, a first bend pipe, a vertical pipe, a second bend pipe, a second horizontal pipe and an inlet smoke hood inclined pipe connected sequentially from end to end, an ammonia injection device is provided in the vertical pipe, the inlet of the ammonia injection device is fixedly connected to a mixed gas inlet pipeline, at least one first guide plate is provided in the first bend pipe, at least one second guide plate is provided in the second bend pipe, a third guide plate is provided on the inner left side of the inlet smoke hood inclined pipe, and a fourth guide plate is provided on the inner right side of the inlet smoke hood inclined pipe.

[0006] The following are further optimizations and / or improvements to the above-mentioned utility model technical solution: The first bend pipe has three first guide plates spaced apart on the left and right. Each first guide plate includes a first arc-shaped guide plate and a first guide inclined plate. A first guide inclined plate is fixedly installed at the upper end of each first guide plate. Each first guide inclined plate is inclined with the left side higher than the right side. The second bend pipe has two second guide plates spaced apart on the left and right. The second guide plates include a second arc-shaped guide plate. The left inner side of the inlet smoke hood inclined pipe has a third guide plate. The third guide plate includes a second guide inclined plate, a third guide inclined plate, and a third arc-shaped guide plate. The left inner side of the inlet smoke hood inclined pipe has a second guide inclined plate, a third guide inclined plate, and a third arc-shaped guide plate spaced apart on the upper and lower sides. The second guide inclined plate and the third guide inclined plate are inclined with the left side higher than the right side. The right inner side of the inlet smoke hood inclined pipe has a fourth guide plate. The fourth guide plate includes a fourth guide inclined plate. The fourth guide inclined plate is inclined with the left side higher than the right side.

[0007] The tangential direction of each of the first arc-shaped guide vanes is inclined from left to right, and the angle between each first guide vane and the vertical plane is between 10° and 20°. The tangential direction of each of the second arc-shaped guide vanes is inclined from left to right, and the angle between the second and third guide vanes and the horizontal plane is between 2° and 8°. The tangential direction of the third arc-shaped guide vane is inclined from left to right, and the central angle of the third arc-shaped guide vane is between 50° and 75°. The angle between the fourth guide vane and the horizontal plane is between 40° and 50°.

[0008] The above also includes a static mixer, the inlet of which is fixedly connected to a dilution gas inlet pipeline, the dilution gas inlet pipeline is fixedly connected to an ammonia inlet pipeline, a dilution fan is installed on the dilution gas inlet pipeline, and a mixed gas inlet pipeline is fixedly connected between the outlet of the static mixer and the inlet of the ammonia injection device.

[0009] The aforementioned ammonia injection device includes a primary ammonia injection grid and a secondary ammonia injection grid. The primary and secondary ammonia injection grids are spaced apart from bottom to top inside the vertical flue. Each ammonia injection grid has several ammonia injection branch pipes spaced apart on the left and right. Each ammonia injection branch pipe has ammonia injection holes spaced apart on the front and back. Each ammonia injection hole is equipped with a nozzle. A mixed gas inlet pipeline is fixedly connected between the right inlet of the primary ammonia injection grid and the static mixer. A mixed gas inlet branch pipe is fixedly connected between the right inlet of the secondary ammonia injection grid and the mixed gas inlet pipeline.

[0010] The above also includes steam soot blowers, which are installed on the sidewall of the SCR denitrification reactor and on the upper side of each catalyst layer.

[0011] The above also includes a nitrogen oxide concentration detector, and a flue gas circulation pipeline is fixedly connected between the flue gas outlet pipe and the ammonia inlet pipeline, with a nitrogen oxide concentration detector installed on the flue gas circulation pipeline.

[0012] This utility model has a reasonable and compact structure and is easy to use. By setting a first guide plate, a second guide plate, a third guide plate and a fourth guide plate at each connection in the intake flue, the optimized flow field ammonia gas and flue gas are fully mixed, reducing ammonia escape, lowering operating costs, and also helping to reduce the impact and wear of flue gas on the catalyst in each catalyst layer, thus extending the service life of the catalyst. Attached Figure Description

[0013] Appendix Figure 1 This is a schematic diagram of the process flow of this utility model.

[0014] Appendix Figure 2 For the appendix Figure 1 Enlarged schematic diagram of the first guide vane.

[0015] Appendix Figure 3 For the appendix Figure 1 Enlarged schematic diagram of the third guide vane.

[0016] Appendix Figure 4 For the appendix Figure 1 Enlarged schematic diagram of the fourth guide vane.

[0017] The codes in the attached diagram are as follows: 1 for SCR denitrification reactor, 2 for flue gas rectifier, 3 for primary catalyst layer, 4 for secondary catalyst layer, 5 for first horizontal flue, 6 for first bend, 7 for vertical flue, 8 for second bend, 9 for second horizontal flue, 10 for inlet hood inclined tube, 11 for first arc-shaped guide plate, 12 for first inclined guide plate, 13 for second arc-shaped guide plate, 14 for second inclined guide plate, 15 for third inclined guide plate, and 16 for third arc-shaped guide plate. 17 is the fourth guide plate, 18 is the exhaust pipe, 19 is the static mixer, 20 is the dilution gas inlet pipe, 21 is the ammonia inlet pipe, 22 is the dilution fan, 23 is the mixed gas inlet pipe, 24 is the primary ammonia injection grille, 25 is the secondary ammonia injection grille, 26 is the mixed gas inlet branch pipe, 27 is the steam soot blower, 28 is the nitrogen oxide concentration detector, 29 is the flue gas circulation pipe, α is the first included angle, β is the second included angle, γ is the third included angle, and θ is the first central angle. Detailed Implementation

[0018] This utility model is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this utility model and the actual situation.

[0019] Unless otherwise specified, all equipment and devices used in this invention are existing and commonly known in the field. For example, the flue gas rectifier 2, the primary ammonia injection grille 24, the secondary ammonia injection grille 25, the steam soot blower 27, and the nitrogen oxide concentration detector 28 are existing and commonly known equipment.

[0020] In this utility model, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0021] The present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1: As shown in the attached document Figure 1 , 2 As shown, the precision ammonia injection SCR denitrification device based on flow field optimization includes an SCR denitrification reactor 1. The top inlet of the SCR denitrification reactor 1 is fixedly connected to an inlet flue pipe, and the bottom outlet of the SCR denitrification reactor 1 is fixedly connected to an outlet flue pipe 18. The inner side of the SCR denitrification reactor 1 is provided with a flue gas rectifier 2, a primary catalyst layer 3, and a secondary catalyst layer 4 from top to bottom. The inlet flue pipe includes a first horizontal flue pipe 5, a first bend pipe 6, a vertical flue pipe 7, a second bend pipe 8, a second horizontal flue pipe 9, and an inlet smoke hood inclined pipe 10 connected end to end. An ammonia injection device is provided in the vertical flue pipe 7. The inlet of the ammonia injection device is fixedly connected to a mixed gas inlet pipeline 23. At least one first guide plate is provided in the first bend pipe 6, at least one second guide plate is provided in the second bend pipe 8, a third guide plate is provided on the inner left side of the inlet smoke hood inclined pipe 10, and a fourth guide plate is provided on the inner right side of the inlet smoke hood inclined pipe 10.

[0022] The working process of this invention involves sending a mixed gas (ammonia and air) through the mixed gas inlet pipeline 23 to the ammonia injection device, which then injects ammonia into the vertical flue pipe 7. Simultaneously, the flue gas is sent to the SCR denitrification reactor 1 through the first horizontal flue pipe 5, the first bend pipe 6, the vertical flue pipe 7, the second bend pipe 8, the second horizontal flue pipe 9, and the inlet smoke hood inclined pipe 10. The flue gas is then rectified by the flue gas rectifier 2 within the SCR denitrification reactor 1, and then undergoes denitrification treatment through the primary catalyst layer 3 and the secondary catalyst layer 4. This invention achieves flue gas rectification through the installation of a first guide plate, a second guide plate, a third guide plate, and a fourth guide plate, effectively guiding the flue gas and resulting in a uniform flue gas flow field distribution, thus improving the contact area and efficiency of the denitrification reaction. It effectively solves the problem of existing SCR denitrification reactors where the guide plate installation in the inlet flue is singular, failing to effectively guide the flue gas and leading to uneven flow field distribution, resulting in low contact area and efficiency of the denitrification reaction.

[0023] The above-mentioned precision ammonia injection SCR denitrification device based on flow field optimization can be further optimized and / or improved according to actual needs: Example 2: Its difference from Example 1 is as follows: (See attached) Figure 1 , 2As shown, three first guide plates are spaced apart on the left and right sides inside the first bend 6. Each first guide plate includes a first arc-shaped guide plate 11 and a first guide inclined plate 12. A first guide inclined plate 12 is fixedly installed at the upper end of each first guide plate. Each first guide inclined plate 12 is inclined with the left side higher than the right side. Two second guide plates are spaced apart on the left and right sides inside the second bend 8. The second guide plates include a second arc-shaped guide plate 13. A third guide plate is provided on the inner side of the left side of the inlet smoke hood inclined pipe 10. The flow plate includes a second guide plate 14, a third guide plate 15, and a third arc-shaped guide plate 16. The second guide plate 14, the third guide plate 15, and the third arc-shaped guide plate 16 are provided at intervals on the upper and lower sides of the inner left side of the inlet smoke hood inclined tube 10. The second guide plate 14 and the third guide plate 15 are both inclined with the left side higher than the right side. A fourth guide plate is provided on the inner right side of the inlet smoke hood inclined tube 10. The fourth guide plate includes a fourth guide plate 17, which is inclined with the left side higher than the right side.

[0024] In this invention, the angle, shape, and number of each guide plate have been further optimized. After optimization, it is ensured that the flue gas is evenly distributed in the catalyst layer, thereby improving the contact area and efficiency of the denitrification reaction.

[0025] In this invention, by setting a first guide plate, a second guide plate, a third guide plate, and a fourth guide plate at each connection point in the intake flue, the optimized flow field ammonia and flue gas are fully mixed, reducing ammonia escape, lowering operating costs, and also helping to reduce the impact and wear of flue gas on the catalysts in each catalyst layer, thus extending the service life of the catalysts.

[0026] Example 3: Its difference from Example 2 is as follows: (See attached) Figure 1 , 2 As shown, the tangent direction of each first arc-shaped guide plate 11 is inclined from left to right, and the angle between each first guide plate 12 and the vertical plane is the first included angle α, which is between 10° and 20°, preferably 15°; the tangent direction of each second arc-shaped guide plate 13 is inclined from left to right, and the angle between the second guide plate 14 and the third guide plate 15 and the horizontal plane is the second included angle β, which is between 2° and 8°, preferably 5°; the tangent direction of the third arc-shaped guide plate 16 is inclined from left to right, and the central angle of the third arc-shaped guide plate 16 is the first central angle θ, which is between 50° and 75°, preferably 60°; the angle between the fourth guide plate 17 and the horizontal plane is the third included angle γ, which is between 40° and 50°, preferably 45°.

[0027] In this invention, by adjusting the angle of each guide vane, the flue gas can be better distributed in the flue, reducing the local flow velocity and improving the overall flow field uniformity; by adjusting the shape of each guide vane, it can be made more in line with the flue gas flow characteristics; and by increasing the number of each guide vane in key areas, the flue gas control capability of the flow field can be improved.

[0028] Example 4: Its difference from Examples 1 to 3 is as follows: (See attached) Figure 1 , 2 As shown, it also includes a static mixer 19, with a dilution gas inlet pipeline 20 fixedly connected to the inlet of the static mixer 19, an ammonia inlet pipeline 21 fixedly connected to the dilution gas inlet pipeline 20, a dilution fan 22 provided on the dilution gas inlet pipeline 20, and a mixed gas inlet pipeline 23 fixedly connected between the outlet of the static mixer 19 and the inlet of the ammonia injection device.

[0029] In this invention, ammonia and dilution gas (air) are premixed by a static mixer 19 to achieve an ammonia concentration of 0.5% to 5%.

[0030] Example 5: It differs from Examples 1 to 4 in that, as shown in the appendix... Figure 1 , 2 As shown, the ammonia injection device includes a primary ammonia injection grid 24 and a secondary ammonia injection grid 25. The primary ammonia injection grid 24 and the secondary ammonia injection grid 25 are arranged at intervals from bottom to top in the vertical flue 7. Each ammonia injection grid has several ammonia injection branch pipes arranged at intervals on the left and right. Each ammonia injection branch pipe has ammonia injection holes arranged at intervals on the front and back. Each ammonia injection hole is equipped with a nozzle. The right inlet of the primary ammonia injection grid 24 is fixedly connected to the static mixer 19 by a mixed gas inlet pipeline 23. The right inlet of the secondary ammonia injection grid 25 is fixedly connected to the mixed gas inlet pipeline 23 by a mixed gas inlet branch pipe 26.

[0031] In this invention, the ammonia gas is evenly distributed on the cross-section of the intake flue by setting a primary ammonia injection grille 24 and a secondary ammonia injection grille 25. The nozzle diameter is about 4mm to 6mm. This setting improves the uniformity of the mixing of ammonia gas and flue gas.

[0032] Example 6: Its difference from Examples 1 to 5 is as follows: (See attached) Figure 1 , 2 As shown, it also includes a steam soot blower 27, which corresponds to the side wall of the SCR denitrification reactor 1 and is provided on the upper side of each catalyst layer.

[0033] In this invention, the steam soot blower 27 is used to periodically remove accumulated ash and prevent ash from forming blockages.

[0034] Example 7: Its difference from Examples 1 to 6 is as follows: (See attached) Figure 1 ,2 As shown, it also includes a nitrogen oxide concentration detector 28, and a flue gas circulation pipeline 29 is fixedly connected between the flue gas outlet pipe 18 and the ammonia inlet pipeline 21. The flue gas circulation pipeline 29 is equipped with a nitrogen oxide concentration detector 28.

[0035] In this invention, a nitrogen oxide concentration detector 28 is used to detect the concentration of nitrogen oxides in the gas in the exhaust pipe 18. When the concentration of nitrogen oxides exceeds the limit, the gas in the exhaust pipe 18 is sent to the static mixer 19 through the flue gas circulation pipeline 29 and the ammonia inlet pipeline 21. When the concentration of ammonia in the mixed gas in the static mixer 19 is within the specified value, it is sent to the primary ammonia injection grid 24 and the secondary ammonia injection grid 25 by the mixed gas inlet pipeline 23 and the mixed gas inlet branch pipe 26, respectively.

[0036] Depending on the needs, the various pipelines and equipment of this device may also be equipped with conventional valves, thermometers, and pressure gauges that are known and commonly used in the field, according to production requirements.

[0037] The above technical features constitute the embodiments of this utility model, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0038] The usage process of this utility model embodiment is as follows: First, the mixed gas (ammonia and air) is sent to the ammonia injection device through the mixed gas inlet pipeline 23. Ammonia is injected into the vertical flue pipe 7 through the first-stage ammonia injection grid 24 and the second-stage ammonia injection grid 25. At the same time, the flue gas is sent to the SCR denitrification reactor 1 through the first horizontal flue pipe 5, the first bend pipe 6, the vertical flue pipe 7, the second bend pipe 8, the second horizontal flue pipe 9 and the inlet smoke hood inclined pipe 10. The flue gas is rectified by the flue gas rectifier 2 in the SCR denitrification reactor 1, and then denitrified through the first-stage catalyst layer 3 and the second-stage catalyst layer 4. The denitrified flue gas is sent out through the exhaust flue pipe 18.

Claims

1. A precision ammonia injection SCR denitrification device based on flow field optimization, characterized in that... The reactor includes an SCR denitrification reactor. The top inlet of the SCR denitrification reactor is fixedly connected to an inlet flue pipe, and the bottom outlet of the SCR denitrification reactor is fixedly connected to an outlet flue pipe. Inside the SCR denitrification reactor, from top to bottom, are arranged a flue gas rectifier, a primary catalyst layer, and a secondary catalyst layer. The inlet flue pipe includes a first horizontal flue pipe, a first bend, a vertical flue pipe, a second bend, a second horizontal flue pipe, and an inlet hood inclined pipe, connected sequentially from end to end. An ammonia injection device is installed inside the vertical flue pipe, and the inlet of the ammonia injection device is fixedly connected to a mixed gas inlet pipeline. At least one first guide plate is installed inside the first bend, at least one second guide plate is installed inside the second bend, a third guide plate is installed on the inner left side of the inlet hood inclined pipe, and a fourth guide plate is installed on the inner right side of the inlet hood inclined pipe.

2. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 1, characterized in that... Three first guide plates are spaced apart on the left and right sides inside the first bend. Each first guide plate includes a first arc-shaped guide plate and a first guide inclined plate. A first guide inclined plate is fixedly installed at the upper end of each first guide plate. Each first guide inclined plate is inclined with the left side higher than the right side. Two second guide plates are spaced apart on the left and right sides inside the second bend. The second guide plate includes a second arc-shaped guide plate. The third guide plate includes a second guide inclined plate, a third guide inclined plate, and a third arc-shaped guide plate. The second guide inclined plate, the third guide inclined plate, and the third arc-shaped guide plate are spaced apart on the upper and lower sides of the inner left side of the inlet smoke hood inclined pipe. The second guide inclined plate and the third guide inclined plate are inclined with the left side higher than the right side. The fourth guide plate includes a fourth guide inclined plate. The fourth guide inclined plate is inclined with the left side higher than the right side.

3. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 2, characterized in that... The tangent direction of each first arc-shaped guide vane is inclined from left to right, and the angle between each first guide vane and the vertical plane is between 10° and 20°. The tangent direction of each second arc-shaped guide vane is inclined from left to right, and the angle between the second and third guide vanes and the horizontal plane is between 2° and 8°. The tangent direction of the third arc-shaped guide vane is inclined from left to right, and the central angle of the third arc-shaped guide vane is between 50° and 75°. The angle between the fourth guide vane and the horizontal plane is between 40° and 50°.

4. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 1, 2, or 3, characterized in that... It also includes a static mixer, the inlet of which is fixedly connected to a dilution gas inlet pipeline, the dilution gas inlet pipeline is fixedly connected to an ammonia inlet pipeline, a dilution fan is installed on the dilution gas inlet pipeline, and a mixed gas inlet pipeline is fixedly connected between the outlet of the static mixer and the inlet of the ammonia injection device.

5. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 1, 2, or 3, characterized in that... The ammonia injection device includes a primary ammonia injection grid and a secondary ammonia injection grid. The primary and secondary ammonia injection grids are arranged at intervals from bottom to top inside the vertical flue. Each ammonia injection grid has several ammonia injection branch pipes arranged at intervals on the left and right. Each ammonia injection branch pipe has ammonia injection holes arranged at intervals on the front and back. Each ammonia injection hole is equipped with a nozzle. The right inlet of the primary ammonia injection grid is fixedly connected to the static mixer by a mixed gas inlet pipeline. The right inlet of the secondary ammonia injection grid is fixedly connected to the mixed gas inlet pipeline by a mixed gas inlet branch pipe.

6. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 4, characterized in that... The ammonia injection device includes a primary ammonia injection grid and a secondary ammonia injection grid. The primary and secondary ammonia injection grids are arranged at intervals from bottom to top inside the vertical flue. Each ammonia injection grid has several ammonia injection branch pipes arranged at intervals on the left and right. Each ammonia injection branch pipe has ammonia injection holes arranged at intervals on the front and back. Each ammonia injection hole is equipped with a nozzle. The right inlet of the primary ammonia injection grid is fixedly connected to the static mixer by a mixed gas inlet pipeline. The right inlet of the secondary ammonia injection grid is fixedly connected to the mixed gas inlet pipeline by a mixed gas inlet branch pipe.

7. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 1, 2, 3, or 6, characterized in that... It also includes steam soot blowers, which are installed on the sidewall of the SCR denitrification reactor and on the upper side of each catalyst layer.

8. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 4, characterized in that... It also includes steam soot blowers, which are installed on the sidewall of the SCR denitrification reactor and on the upper side of each catalyst layer.

9. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 5, characterized in that... It also includes steam soot blowers, which are installed on the sidewall of the SCR denitrification reactor and on the upper side of each catalyst layer.

10. The precision ammonia injection SCR denitrification device based on flow field optimization according to claim 1, 2, 3, 6, 8, or 9, characterized in that... It also includes a nitrogen oxide concentration detector, and a flue gas circulation pipeline is fixedly connected between the flue gas outlet pipe and the ammonia inlet pipeline, with a nitrogen oxide concentration detector installed on the flue gas circulation pipeline.

Images