Ammonia smoke flow mixing device with ash removal and premixing functions

Abstract

The utility model relates to the technical field of thermal power generation denitration, in particular to an ammonia-smoke flow mixing device with deashing and premixing functions, an ammonia-smoke flow mixing component is arranged above an ammonia spraying grid and comprises a plurality of ammonia-smoke flow mixing units, each ammonia-smoke flow mixing unit comprises a mixer, a premixing and ash removing hopper, a vertical supporting rod and a horizontal supporting rod, when ammonia gas and smoke flow through the ammonia-smoke flow mixing assembly, the smoke firstly collides with the premixing and ash removing hopper in a head-on mode, the premixing and ash removing hopper blocks dust in the smoke, the dust in the smoke is made to settle and enter an ash hopper below a flue, and the smoke is discharged from the mixer. Flue gas forms a vortex effect before entering the mixer, after the flue gas passes through the mixer, the design of the top plate and the side plate enhances the vortex effect of the flue gas, the through holes enhance the mixing effect of the flue gas and ammonia gas, and the flue gas and the ammonia gas are continuously and fully mixed, so that the ammonia gas concentration distribution in the mixed gas is relatively uniform before the mixed gas reaches the front section of a catalyst layer; and the risks of excessive ammonia spraying and ammonia escape are reduced.

Description

Technical Field

[0001] This utility model relates to the field of denitrification technology in thermal power generation, specifically to an ammonia flue gas mixing device with ash removal and premixing functions. Background Technology

[0002] NOx emissions from coal-fired power plants account for more than 40% of NOx emissions from coal combustion. It is one of the main pollutants causing acid rain, the greenhouse effect, and smog. Selective catalytic reduction (SCR) denitrification technology has high denitrification efficiency, no secondary pollution, and is a mature technology that is widely used in large coal-fired units.

[0003] The existing ammonia injection grid is equipped with multiple ammonia injection pipes, and each ammonia injection pipe is equipped with multiple ammonia injection nozzles at average intervals. The axis of each ammonia injection nozzle is aligned with the flue gas flow direction. Ammonia gas enters the flue gas from the ammonia injection pipes and passes through the ammonia injection nozzles. The ammonia gas mixes with the flue gas by means of airflow convection and concentration difference diffusion.

[0004] The ammonia injection device described above is characterized by a high ammonia concentration near the injection port and a low concentration between the injection ports. However, due to the uniform spacing and numerous number of injection ports, the ammonia concentration across the entire injection section is relatively uniform. Within the flue gas distance between the injection section and the catalyst, ammonia diffuses from high-concentration areas to low-concentration areas via airflow convection and concentration differences. Theoretically, sufficiently strong ammonia diffusion can achieve uniform ammonia concentration in front of the catalyst. However, numerical simulations of the SCR denitrification flow field, model tests, and engineering practices show that relying solely on airflow convection and concentration differences for ammonia diffusion is insufficient to achieve a uniform ammonia concentration distribution in the mixed gas in front of the catalyst. Furthermore, dust in the flue gas can affect catalyst activity, thereby impacting denitrification efficiency.

[0005] To address the aforementioned issues, a technical problem urgently needs to be solved by employing a device that can both remove dust from the flue gas and improve the uniformity of ammonia concentration in the mixture before it reaches the catalyst layer. Utility Model Content

[0006] The purpose of this invention is to provide an ammonia fume mixing device with dust removal and premixing functions, which realizes the premixing of flue gas and ammonia gas and blocks dust in the flue gas. This enables the ammonia fume concentration distribution in the mixed gas to be more uniform before reaching the catalyst layer, reducing the risk of excessive ammonia injection and ammonia escape.

[0007] Existing denitrification flue gas systems include an ammonia injection grid, a rectifier grid layer, a catalyst layer, a detection layer, and an ash hopper. Flue gas in the denitrification flue gas passes sequentially through the ammonia injection grid, rectifier grid layer, catalyst layer, and detection layer. The catalyst layer consists of two layers, and the ash hopper is located on the bottom surface of the vertical flue gas duct at the denitrification inlet. This invention provides an ammonia flue gas mixing device with cleaning and premixing functions, comprising an ammonia flue gas mixing assembly located within the vertical flue gas duct at the denitrification inlet, above the ammonia injection grid. The ammonia flue gas mixing assembly includes multiple ammonia flue gas mixing units evenly distributed in a matrix. Each ammonia flue gas mixing unit includes a mixer, a premixing and cleaning hopper, a vertical support rod, and a horizontal support. The mixer is fixedly connected to the top of the vertical support rod, the premixing and cleaning hopper is fixedly connected to the middle of the vertical support rod, and the horizontal support rod is fixedly connected to the bottom of the vertical support rod. The mixer is located above the premixing and cleaning hopper, which is located above the horizontal support rod. The mixer, premixing and cleaning hopper, and vertical support rod are coaxial. The mixer includes a top plate and side plates. The top plate is rectangular, and the side plates are trapezoidal. There are four side plates, and the tops of the four side plates are fixedly connected to the four sides of the top plate. The four side plates extend outward from the bottom surface of the top plate, and the sides of the four side plates are fixedly connected in pairs. The inner diameter of the rectangle formed by the bottom edges of the four side plates is larger than the outer diameter of the top plate. The top plate has multiple through holes. The premixing and cleaning hopper is inverted conical.

[0008] Furthermore, the horizontal support rod in each ammonia fume mixing unit is a single support rod, and the horizontal support rods of two adjacent ammonia fume mixing units in multiple ammonia fume mixing units are coaxially and fixedly connected. The horizontal support rod of the ammonia fume mixing unit closest to the inner wall of the flue is fixedly connected to the inner wall of the flue.

[0009] Furthermore, each ammonia fume mixing unit has two horizontal support rods arranged in a cross shape. The two support rods of two adjacent ammonia fume mixing units are coaxially fixedly connected. The two support rods of the horizontal support rod of the ammonia fume mixing unit closest to the inner wall of the flue are both fixedly connected to the inner wall of the flue.

[0010] Furthermore, the through holes are rectangular, and multiple through holes are evenly distributed in a matrix.

[0011] Furthermore, the included angle between the premixing and cleaning hoppers is α, where α = 130°.

[0012] Furthermore, the mixer, premixing and dust removal hopper, vertical support rod, and horizontal support rod are all made of stainless steel.

[0013] The beneficial effects of this invention are as follows: This invention achieves pre-mixing of flue gas and ammonia, and blocks dust in the flue gas, causing the dust to settle into the ash hopper below the flue; the mixer is used to mix NH3 and flue gas after ammonia injection, ensuring uniform mixing; the rectifying grid layer is used to rectify the flue gas and NH3 in the denitrification flue; the catalyst layer is used for the reaction denitrification of NOx and NH3 in the flue gas; the detection layer is used to detect the NOx and NH3 concentrations in the denitrification flue gas; and the ash hopper is used to collect the flue gas intercepted by the ammonia-flue gas mixing component in the inlet vertical flue. Dust in the gas; when ammonia and flue gas flow through the ammonia fume mixing component, the flue gas first impacts the premixing and cleaning hopper. The premixing and cleaning hopper blocks the dust in the flue gas, causing the dust in the flue gas to settle into the ash hopper under the flue. Before the flue gas enters the mixer, a vortex effect is formed. After passing through the mixer, the design of the top plate and side plate enhances the flue gas vortex effect. The through holes enhance the mixing effect of flue gas and ammonia. The flue gas and ammonia are continuously and fully mixed, so that the ammonia fume concentration distribution in the mixed gas is relatively uniform before reaching the catalyst layer, reducing the risk of excessive ammonia injection and ammonia escape. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the ammonia fume mixing unit of this utility model;

[0015] Figure 2 This is a top view of the mixer of this utility model;

[0016] Figure 3 This is a schematic diagram showing the arrangement of this utility model within the flue.

[0017] Figure 4 This is a top view of the ammonia fume mixing assembly with a single horizontal support rod in this utility model;

[0018] Figure 5 This is a top view of the ammonia fume mixing assembly with two horizontal support rods in a cross shape, as described in this utility model.

[0019] In the diagram: 1. Ammonia injection grid; 2. Ammonia fume mixing assembly; 201. Ammonia fume mixing unit; 3. Rectifying grid layer; 4. Catalyst layer; 5. Detection layer; 6. Ash hopper; 7. Mixer; 701. Top plate; 7011. Through hole; 702. Side plate; 8. Premixing and ash removal hopper; 9. Vertical support rod; 10. Horizontal support rod. Detailed Implementation

[0020] like Figures 1-5As shown, in the prior art, the denitrification flue includes an ammonia injection grid 1, a rectifier grid layer 3, a catalyst layer 4, a detection layer 5, and an ash hopper 6. The flue gas in the denitrification flue passes sequentially through the ammonia injection grid 1, the rectifier grid layer 3, the catalyst layer 4, and the detection layer 5. The catalyst layer 4 has two layers. The ash hopper 6 is located on the bottom surface of the vertical flue at the denitrification inlet. The present invention provides an ammonia flue mixing device with ash removal and premixing functions, including an ammonia flue mixing assembly 2. The ammonia flue mixing assembly 2 is located inside the vertical flue at the denitrification inlet and above the ammonia injection grid 1. The ammonia flue mixing assembly 2 includes multiple ammonia flue mixing units 201, which are evenly distributed in a matrix. Each ammonia flue mixing unit 201 includes a mixer 7, a premixing and ash removal hopper 8, a vertical support rod 9, and a horizontal support rod 10. The mixer 7 is fixedly connected to the top of the vertical support rod 9, and the premixing and ash removal hopper 8 is fixedly connected to the vertical support rod 10. The horizontal support rod 10 is fixedly connected to the bottom of the vertical support rod 9 in the middle of the support rod 9. The mixer 7 is located above the premixing and dust removal hopper 8, which is located above the horizontal support rod 10. The mixer 7, the premixing and dust removal hopper 8, and the vertical support rod 9 are coaxial. The mixer 7 includes a top plate 701 and side plates 702. The top plate 701 is rectangular, and the side plates 702 are trapezoidal. There are four side plates 702, and the tops of the four side plates 702 are respectively fixedly connected to... The top plate 701 is attached to the four sides. The four side plates 702 extend outward from the bottom surface of the top plate 701. The sides of the four side plates 702 are fixedly connected in pairs. The inner diameter of the rectangle formed by the bottom edges of the four side plates 702 is larger than the outer diameter of the top plate 701. The top plate 701 is provided with multiple through holes 7011. The premixing and dust removal hopper 8 is inverted conical. The through holes 7011 are rectangular and the multiple through holes 7011 are evenly distributed in a matrix. The included angle inside the premixing and dust removal hopper 8 is α, where α = 130°.

[0021] The mixer 7, the premixing and dust removal hopper 8, the vertical support rod 9, and the horizontal support rod 10 are all made of stainless steel.

[0022] In this embodiment, the distance between the ammonia fume mixing component 2 and the ammonia injection grid 1 is 4m-5m; the overall height of the mixer 7 is 375mm; the distance between the bottom surface of the mixer 7 and the bottom of the premixing and ash removal hopper 8 is 400mm; the length of the premixing and ash removal hopper 8 is 300mm; and the through hole 7011 is a square with an inner diameter of 50mm×50mm.

[0023] As an embodiment of this utility model, the horizontal support rod 10 in each ammonia fume mixing unit 201 is a single support rod. The horizontal support rods 10 of two adjacent ammonia fume mixing units 201 are coaxially fixedly connected, and the horizontal support rod 10 of the ammonia fume mixing unit 201 closest to the inner wall of the flue is fixedly connected to the inner wall of the flue.

[0024] For multiple ammonia fume mixing units 201 evenly distributed in a matrix, the spacing between the horizontal ammonia fume mixing units 201 is generally required to be controlled at 1800mm-2000mm, and the spacing between the vertical ammonia fume mixing units 201 is required to be controlled at 1500mm-1800mm; it can be flexibly adjusted according to the rectangular size of the flue.

[0025] In another embodiment of this utility model, each ammonia fume mixing unit 201 has two horizontal support rods 10, which are cross-shaped. The two support rods of the horizontal support rods 10 of two adjacent ammonia fume mixing units 201 are coaxially fixedly connected. The two support rods of the horizontal support rods 10 of the ammonia fume mixing unit 201 closest to the inner wall of the flue are both fixedly connected to the inner wall of the flue.

[0026] The function of the horizontal support rod 10 is to provide support between the ammonia fume mixing units 201 and between the ammonia fume mixing units 201 and the inner wall of the flue. Therefore, the horizontal support rod 10 can be a single rod or two rods in a cross shape, as long as it can provide a stable connection. In actual implementation, it can be used flexibly according to the flue size and the number of ammonia fume mixing units 201.

[0027] This invention achieves premixing of flue gas and ammonia, and blocks dust in the flue gas, causing the dust to settle into the ash hopper 6 under the flue; the mixer 7 is used to mix NH3 and flue gas after ammonia injection, so that the flue gas and NH3 are mixed evenly; the rectifier grid layer 3 is used to rectify the flue gas and NH3 in the denitrification flue; the catalyst layer 4 is used for the reaction denitrification of NOx and NH3 in the flue gas; the detection layer 5 is used to detect the NOx and NH3 concentrations of the flue gas after denitrification; the ash hopper 6 is used to collect dust in the flue gas intercepted by the ammonia flue gas mixing component 2 in the inlet vertical flue.

[0028] When ammonia and flue gas flow through the ammonia-fume mixing assembly 2, the flue gas first impacts the premixing and cleaning hopper 8. The premixing and cleaning hopper 8 blocks the dust in the flue gas, causing the dust in the flue gas to settle into the ash hopper 6 under the flue. Before the flue gas enters the mixer 7, a vortex effect is formed. After passing through the mixer 7, the design of the top plate 701 and the side plate 702 strengthens the flue gas vortex effect. The through hole 7011 enhances the mixing effect of flue gas and ammonia. The flue gas and ammonia are continuously and fully mixed, so that the ammonia concentration distribution in the mixed gas is relatively uniform before reaching the catalyst layer 3, reducing the risk of excessive ammonia injection and ammonia escape.

Claims

1. An ammonia flue gas mixing device with ash removal and premixing functions, the denitration flue gas channel comprising an ammonia injection grid (1), a rectification grid layer (3), a catalyst layer (4), a detection layer (5) and an ash hopper (6), the flue gas in the denitration flue gas channel sequentially passes through the ammonia injection grid (1), the rectification grid layer (3), the catalyst layer (4) and the detection layer (5), the catalyst layer (4) is provided with two layers, and the ash hopper (6) is arranged on the bottom surface of the vertical flue gas channel at the denitration inlet, characterized in that: The application relates to a flue gas mixing assembly (2) arranged in a denitration inlet vertical flue, the flue gas mixing assembly (2) being arranged above an ammonia injection grid (1), the flue gas mixing assembly (2) comprising a plurality of flue gas mixing units (201) arranged in a matrix, each flue gas mixing unit (201) comprising a mixer (7), a premixing and dust cleaning hopper (8), a vertical support rod (9) and a horizontal support rod (10), the mixer (7) being fixedly connected to the top end of the vertical support rod (9), the premixing and dust cleaning hopper (8) being fixedly connected to the middle part of the vertical support rod (9), the horizontal support rod (10) being fixedly connected to the bottom end of the vertical support rod (9), the mixer (7) being arranged above the premixing and dust cleaning hopper (8), the premixing and dust cleaning hopper (8) being arranged above the horizontal support rod (10), the mixer (7), the premixing and dust cleaning hopper (8) and the vertical support rod (9) being coaxial, the mixer (7) comprising a top plate (701) and a side plate (702), the top plate (701) being rectangular, the side plate (702) being trapezoidal, four side plates (702) being arranged, the four side plates (702) being fixedly connected to the four sides of the top plate (701) respectively, the four side plates (702) being inclinedly extended out of the bottom surface of the top plate (701), the side edges of the four side plates (702) being fixedly connected to each other, the bottom edges of the four side plates (702) forming a rectangle with an inner diameter larger than the outer diameter of the top plate (701), a plurality of through holes (7011) being arranged on the top plate (701), and the premixing and dust cleaning hopper (8) being inverted conical. ​ 2. The ammonia flue gas mixing device with ash removal and premixing functions according to claim 1, characterized in that: The horizontal support rod (10) in each flue gas mixing unit (201) is a single support rod, the horizontal support rods (10) of two adjacent flue gas mixing units (201) in the plurality of flue gas mixing units (201) are coaxially fixedly connected, and the horizontal support rod (10) of the flue gas mixing unit (201) closest to the inner wall of the flue is fixedly connected to the inner wall of the flue.

3. The ammonia flue gas mixing device with ash removal and premixing functions according to claim 1, characterized in that: The horizontal support rod (10) in each flue gas mixing unit (201) comprises two support rods, the two support rods are in a cross shape, the two support rods of the horizontal support rods (10) of two adjacent flue gas mixing units (201) in the plurality of flue gas mixing units (201) are coaxially fixedly connected respectively, and the two support rods of the horizontal support rod (10) of the flue gas mixing unit (201) closest to the inner wall of the flue are fixedly connected to the inner wall of the flue.

4. The ammonia flue gas mixing device with ash removal and premixing functions according to any one of claims 2-3, characterized in that: The through holes (7011) are rectangular, and the plurality of through holes (7011) are arranged in a matrix.

5. The ammonia flue gas mixing device with ash removal and premixing function according to claim 4, characterized in that: The premixing and dust cleaning hopper (8) has an included angle a, and a=130 DEG.

6. The ammonia flue gas mixing device with ash removal and premixing functions according to claim 1, characterized in that: The materials of the mixer (7), the premixing and dust cleaning hopper (8), the vertical support rod (9) and the horizontal support rod (10) are stainless steel.

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