Denitration ammonia injection grid

Abstract

The utility model discloses a denitration ammonia spraying grid which comprises an ammonia spraying main pipe, an ammonia spraying unit communicated with the ammonia spraying main pipe, a plurality of nozzles uniformly arranged on the flue gas windward side of the ammonia spraying unit, a plurality of groups of hexsteel and a high-temperature wear-resistant coating layer, the hexsteel is fixed on the flue gas windward side of the ammonia spraying unit, and the high-temperature wear-resistant coating layer is arranged on the hexsteel. The high-temperature wear-resistant coating layer is filled in meshes of the hexsteel and covers the surface of the hexsteel. According to the utility model, the denitration ammonia injection grid can be used for more than 5 years; the accuracy of denitration optimization adjustment is effectively ensured; the service life of the denitration ammonia injection grid is prolonged; potential safety hazards are eliminated, maintenance cost is reduced, ammonia spraying amount is saved, air pre-heater pressure difference is reduced, and unit operation economical efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology, and more specifically, to a denitrification ammonia spray grid. Background Technology

[0002] Nitrogen oxides (NOx) are one of the main sources of air pollution, with emissions primarily originating from the direct combustion of energy sources such as coal. Technical measures for controlling NOx emissions can be categorized into primary and secondary measures: primary measures reduce NOx formation during combustion through various technological means; secondary measures remove already generated NOx from flue gas using technical methods, i.e., flue gas denitrification technology.

[0003] Among numerous denitrification technologies, Selective Catalytic Reduction (SCR) boasts the highest denitrification efficiency (over 90%) and is the most widely used. The SCR denitrification process flow is as follows: Liquid ammonia is vaporized in an evaporator before being injected into the flue gas in the SCR system; the vaporized ammonia is mixed with dilution air and uniformly injected into the flue gas upstream of the SCR reactor through a denitrification ammonia injection grid; the thoroughly mixed ammonia reacts chemically with nitrogen oxides (NOx) in the flue gas under the action of a catalyst in the SCR reactor, producing nitrogen and water, thereby reducing the NOx emission concentration in the flue gas.

[0004] The ammonia injection grid is a crucial component in an SCR (Selective Catalytic Reduction) system, ensuring thorough mixing of ammonia and flue gas before they enter the SCR reactor. It primarily consists of an ammonia injection header, injection units, and nozzles. The ammonia injection header is the main pipeline for ammonia delivery, connecting to the ammonia supply source. The injection units branch off from the header and are evenly distributed across the flue gas duct cross-section. Multiple nozzles are evenly positioned on the windward side of each injection unit, injecting ammonia gas at a specific angle and velocity into the flue gas duct, thus ensuring uniform diffusion of the ammonia within the duct.

[0005] The nozzle is located on the windward side of the flue gas. Due to its unique design, protruding beyond the ammonia injection unit, wear at the nozzle root and the connection point with the ammonia injection unit is accelerated. If wear and leakage occur, the ammonia injection flow field will be disrupted, making denitrification optimization and adjustment more difficult and affecting the unit's environmentally friendly operation. While ensuring NOx emissions meet standards, the only option is to increase the amount of ammonia injected for denitrification. However, increasing the amount of ammonia injected for denitrification leads to excessive ammonia escape, increasing costs and accelerating air preheater blockage, which also affects the unit's economic operation.

[0006] Typically, abrasion prevention for denitrification ammonia injection grids primarily relies on abrasion-resistant protective tiles. These tiles cover the pipe walls that may suffer severe wear, and maintenance only requires replacing the worn tiles. Since these tiles are installed on the windward side of the ammonia injection unit, they provide some abrasion protection to the pipe walls. However, they cannot provide comprehensive protection for the nozzle roots, and in fact, accelerate wear at the junction of the nozzle roots and the ammonia injection unit, resulting in poor abrasion prevention. The service life of these abrasion-resistant tiles is only one year, and the inability to provide comprehensive protection for the ammonia injection unit limits its overall lifespan to approximately one year. Utility Model Content

[0007] To address the shortcomings of existing technologies, this utility model provides a denitrification ammonia injection grid, which reduces component wear by treating the root of the nozzle and the ammonia injection unit with anti-wear measures.

[0008] The technical solution adopted in this utility model is as follows.

[0009] This utility model provides a denitrification ammonia injection grid, including an ammonia injection main pipe, an ammonia injection unit connected to the ammonia injection main pipe, and multiple nozzles evenly arranged on the windward side of the flue gas of the ammonia injection unit. It also includes multiple sets of hexagonal mesh and a high-temperature wear-resistant coating layer. The hexagonal mesh is fixed on the windward side of the flue gas of the ammonia injection unit, and the high-temperature wear-resistant coating layer fills the mesh holes of the hexagonal mesh and covers the mesh surface of the hexagonal mesh.

[0010] Preferably, the height of the hexagonal mesh is matched with the thickness of the high-temperature wear-resistant coating layer to ensure their interaction. This allows the high-temperature wear-resistant coating to better fill the mesh openings and fully cover the mesh surface, achieving all-around wear protection.

[0011] Preferably, the hexagonal mesh is welded and fixed to the ammonia injection unit along its length. This allows the high-temperature wear-resistant coating to be better applied to the ammonia injection unit via the hexagonal mesh, and also to the junction of the nozzle root and the ammonia injection unit, resulting in better wear resistance.

[0012] Preferably, the distribution plane of the ammonia injection unit is perpendicular to the flue gas flow direction.

[0013] Preferably, the extension direction of the nozzle is parallel to and opposite to the direction of flue gas flow.

[0014] Preferably, the height of the hexagonal mesh is 10-15 mm and the thickness is 1-2 mm. This ensures sufficient strength of the hexagonal mesh, enhancing the adhesion of the high-temperature wear-resistant coating and preventing it from peeling off.

[0015] Preferably, the tortoise shell mesh is made of carbon steel or stainless steel, and the high-temperature wear-resistant coating layer is made of high-strength wear-resistant putty, wear-resistant lining material, or high-temperature wear-resistant lining material with aluminum oxide as the main component.

[0016] The technical solution of this utility model produces the following beneficial effects:

[0017] By treating the root of the nozzle and the ammonia injection unit with anti-wear measures, during unit maintenance, the weld connecting the ammonia injection unit to the main pipe that needs to be replaced is cut off, the unit is moved to the maintenance platform, the surface dust is cleaned, and then a hexagonal mesh is welded on the windward side of the ammonia injection unit. A high-temperature wear-resistant coating layer is applied to the hexagonal mesh, and after it dries, it is welded and installed according to the original weld, thus achieving all-round wear protection.

[0018] The wear-resistant tortoise shell mesh has a service life of more than 5 years, which can guarantee that the denitrification ammonia injection grid can be used for more than 5 years; effectively ensure the accuracy of denitrification optimization and adjustment; increase the service life of the denitrification ammonia injection grid; eliminate safety hazards, reduce maintenance costs, save ammonia injection volume, reduce air preheater pressure differential and improve the economic operation of the unit. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the denitrification ammonia spraying grid of this utility model;

[0021] Figure 2 This is a cross-sectional view of the ammonia injection unit and nozzle anti-wear treatment of the denitrification ammonia injection grid of this utility model;

[0022] Figure 3 This is a schematic diagram of the structure of the ammonia spraying unit and the tortoise shell mesh of this utility model;

[0023] Figure 4 This is a cross-sectional view of the ammonia injection unit and nozzle anti-wear treatment of an existing denitrification ammonia injection grid.

[0024] In the diagram: 1-ammonia injection main pipe, 2-ammonia injection unit, 3-nozzle, 4-hexagonal mesh, 5-high temperature wear-resistant coating layer, 6-protective tile. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0026] In this specification, similar reference numerals in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] like Figure 4 As shown, the existing anti-wear method for the ammonia injection grid involves covering the pipe wall of the ammonia injection unit 2, which may suffer severe wear, with protective tiles 6. During maintenance, only the worn protective tiles 6 need to be replaced. However, since the protective tiles 6 are installed on the windward side of the flue gas of the ammonia injection unit 2, they cannot provide all-round protection for the root of the nozzle 3. Instead, they accelerate the wear at the junction of the nozzle 3 root and the ammonia injection unit 2, resulting in poor anti-wear effect.

[0028] Please refer to Figures 1 to 3 This embodiment provides a denitrification ammonia injection grid, including an ammonia injection main pipe 1, an ammonia injection unit 2 connected to the ammonia injection main pipe 1, and multiple nozzles 3 uniformly arranged on the windward side of the flue gas of the ammonia injection unit 2. It also includes multiple sets of hexagonal mesh 4 and a high-temperature wear-resistant coating layer 5. The hexagonal mesh 4 is fixed to the windward side of the flue gas of the ammonia injection unit 2, and the high-temperature wear-resistant coating layer 5 fills the mesh openings of the hexagonal mesh 4 and covers the mesh surface of the hexagonal mesh 4.

[0029] In a preferred embodiment, the height of the hexagonal mesh 4 is matched with the thickness of the high-temperature wear-resistant coating layer 5 to ensure their interaction. This allows the high-temperature wear-resistant coating to better fill the mesh openings of the hexagonal mesh 4 and fully cover its surface.

[0030] In a preferred embodiment, the hexagonal mesh 4 is welded and fixed to the ammonia injection unit 2 along its length. This allows the high-temperature wear-resistant coating to be better applied to the ammonia injection unit 2 via the hexagonal mesh 4, and also to be better applied at the junction of the nozzle 3 root and the ammonia injection unit 2, resulting in better wear resistance.

[0031] In a preferred embodiment, the distribution plane of the ammonia injection unit 2 is perpendicular to the flue gas flow direction. The extension direction of the nozzle 3 is parallel to and opposite to the flue gas flow direction. This ensures that the ammonia injection direction intersects the flue gas flow direction perpendicularly, thereby greatly reducing the possibility of dust clogging the nozzle 3 during boiler shutdown.

[0032] In a preferred embodiment, the height of the hexagonal mesh 4 is 10-15 mm, and the thickness is 1-2 mm. This ensures sufficient strength of the hexagonal mesh 4, enhancing the adhesion of the high-temperature wear-resistant coating and preventing it from peeling off.

[0033] In a preferred embodiment, the hexagonal mesh 4 is made of carbon steel or stainless steel, and the high-temperature wear-resistant coating layer 5 is made of high-strength wear-resistant mortar, wear-resistant lining material, or high-temperature wear-resistant lining material whose main component is alumina. The high-strength wear-resistant mortar, wear-resistant lining material, or high-temperature wear-resistant lining material is commercially available, for example, wear-resistant lining material or high-temperature wear-resistant lining material produced by Jiangxi Hengda High-Tech Co., Ltd. This results in stronger corrosion resistance for the hexagonal mesh 4 and the high-temperature wear-resistant coating layer 5, thus improving the wear resistance cycle of the denitrification ammonia spraying grid.

[0034] When using this utility model:

[0035] By statistically analyzing the wear of ammonia injection unit 2, during unit maintenance, the weld connecting the damaged ammonia injection unit 2 and the ammonia injection main pipe 1 is cut open, and the ammonia injection unit 2 is transferred to the maintenance platform. The surface dust is cleaned, and first, a hexagonal mesh 4 is welded on the windward side of the flue gas of the ammonia injection unit 2. Then, a high-temperature wear-resistant coating is applied to the hexagonal mesh 4. After drying, it is welded and installed according to the original weld, which can achieve all-round wear protection.

[0036] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A denitration ammonia injection grid comprising an ammonia injection main pipe (1), an ammonia injection unit (2) in communication with the ammonia injection main pipe, and a plurality of nozzles (3) uniformly arranged on the windward side of the flue gas of the ammonia injection unit (2), characterized in that, It also comprises a plurality of sets of tortoise shell net (4) and high temperature wear-resistant coating layer (5), the tortoise shell net (4) is fixed on the windward side of the ammonia injection unit (2), the high temperature wear-resistant coating layer (5) is filled in the mesh of the tortoise shell net (4) and covers the mesh surface of the tortoise shell net (4).

2. The ammonia injection grid for NOx reduction of claim 1, wherein: The height of the tortoise shell net (4) matches the thickness of the high temperature wear-resistant coating layer (5).

3. The ammonia injection grid for NOx reduction of claim 1, wherein: The tortoise shell net (4) is welded and fixed along the length direction of the ammonia injection unit (2).

4. The ammonia injection grid for NOx reduction of claim 1, wherein: The distribution plane of the ammonia injection unit (2) is perpendicular to the flow direction of the flue gas.

5. The ammonia injection grid for NOx reduction of claim 1, wherein: The extension direction of the nozzle (3) is parallel and opposite to the flow direction of the flue gas.

6. The ammonia injection grid for NOx reduction of claim 1, wherein: The height of the tortoise shell net (4) is 10-15mm, and the thickness is 1-2mm.

7. The ammonia injection grid for NOx reduction of claim 1, wherein: The tortoise shell net (4) is carbon steel or stainless steel, and the high temperature wear-resistant coating layer (5) adopts high strength wear-resistant mortar or wear-resistant lining material or high temperature wear-resistant lining material with main component of alumina.

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