Low-temperature flue gas denitration device
Patent Information
- Application Number
- CN202522583607.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2035-12-05
AI Technical Summary
In existing low-temperature flue gas denitrification technologies, uneven mixing of ammonia and flue gas leads to a high ammonia escape rate, increasing ammonia consumption and potentially corroding downstream equipment, thus affecting denitrification efficiency. Furthermore, the cost of retrofitting existing mixing devices is high.
The system employs components such as ammonia injection grilles, static mixers, electric louvers, baffles, and flue gas rectifiers to extend the mixing time of ammonia and flue gas through cross-disturbance and forced turbulence, ensuring uniform mixing.
It significantly improves the mixing uniformity of ammonia and flue gas, reduces ammonia escape rate, reduces ammonia consumption, reduces the risk of corrosion in downstream equipment, improves denitrification efficiency, and reduces retrofit costs.
Smart Images
Figure CN224925910U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of environmental protection equipment technology, and in particular relates to a low-temperature flue gas denitrification device. Background Technology
[0002] In the field of low-temperature flue gas denitrification technology, ammonia, as a reducing agent, undergoes selective catalytic reduction (SCR) with nitrogen oxides (NOx) in flue gas, which is a key process for achieving the harmless conversion of nitrogen oxides.
[0003] In existing technologies, ammonia mixing primarily relies on single-hole or multi-hole direct-injection nozzles of the ammonia injection grid to inject ammonia into the flue gas duct. However, this mixing method has significant drawbacks: First, after ammonia is injected, only a local mixing zone is formed near the injection point. The mixing path is short, and the contact time between ammonia and flue gas is insufficient, making it difficult to achieve sufficient turbulent mixing. Secondly, due to the significant density difference between ammonia and flue gas (ammonia density is approximately 0.77 kg / m³, while flue gas density is approximately 1.2 kg / m³), ammonia is prone to floating or flowing along the wall, resulting in uneven mixing.
[0004] This uneven mixing can lead to localized ammonia excess, increasing ammonia slip (typically exceeding 10 ppm). This not only increases ammonia consumption but can also cause corrosion in downstream equipment (such as air preheater blockage and catalyst poisoning), affecting denitrification efficiency (especially under low-temperature conditions, where reaction kinetics are slow and the requirements for mixing uniformity are even higher). Furthermore, while existing mixing devices such as static mixers can enhance turbulence, their mixing efficiency is often limited, and retrofitting requires adjustments to pipe dimensions, resulting in poor adaptability and high costs.
[0005] Therefore, how to solve the problem of uneven mixing of ammonia and flue gas is a technical problem that urgently needs to be solved in this field.
[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of this application concept, and therefore, the above description is not considered to constitute information related to the technology. Utility Model Content
[0007] This disclosure provides at least one low-temperature flue gas denitrification device.
[0008] In a first aspect, embodiments of this disclosure provide a low-temperature flue gas denitrification device, comprising: Flue gas duct, used to transport a mixed gas flow of flue gas and ammonia; Ammonia injection grilles are installed at the inlet end of flue gas ducts to atomize ammonia water and inject it into the flue gas. A static mixer, installed inside the flue gas duct and located downstream of the ammonia injection grid, is used for forced turbulent mixing; At least two sets of motorized louvers are installed in the flue gas duct downstream of the static mixer, and the air outlets of the two sets of motorized louvers are in opposite directions. A baffle plate, installed at the top corner of the low-temperature denitrification unit, is used to guide the mixed flue gas in. The flue gas rectifier is located at the top of the low-temperature denitrification device to eliminate airflow turbulence.
[0009] In one optional implementation, there are four sets of motorized louvers, evenly distributed along the axial direction of the flue gas duct, and the tilt angle of the blades of each set of motorized louvers is adjustable.
[0010] In one alternative embodiment, the blade angle adjustment range of the motorized louvers is 0° to 90°.
[0011] In one alternative implementation, the blades of two adjacent motorized louvers alternately change their tilt angle and orientation to generate a transversely mixed airflow, extending the mixing time of ammonia and flue gas to 1-3 seconds.
[0012] In one alternative implementation, the static mixer includes multiple twisted blades for splitting the mixed airflow into multiple sub-flows.
[0013] In one optional embodiment, the baffle is an arc-shaped plate structure with a radius of curvature to flue gas duct diameter ratio of 1:1.5, used to reduce airflow resistance.
[0014] In one optional embodiment, the flue gas rectifier is a perforated plate structure with an opening ratio of 30%-50% for uniformly distributing airflow.
[0015] In one optional embodiment, a catalyst layer is provided inside the flue gas duct, comprising at least three catalyst layers, each catalyst layer having a thickness of 100-200 mm and a layer spacing of 50-100 mm.
[0016] In one optional embodiment, the ammonia spraying grid includes a plurality of atomizing nozzles with a nozzle orifice diameter of 0.5-1.0 mm and a spray pressure of 0.1-0.3 MPa.
[0017] The beneficial effects of this invention are as follows: This invention provides a low-temperature flue gas denitrification device. Through the cross-disturbance of the electric louvers and the forced turbulence of the static mixer, the mixing uniformity of ammonia and flue gas is significantly improved, greatly increasing the mixing coefficient. The uniformly mixed ammonia and flue gas significantly reduces the ammonia escape rate, thereby reducing ammonia consumption and the risk of corrosion in downstream equipment. Furthermore, the extended mixing time of ammonia and flue gas meets the reverse time requirements of low-temperature denitrification, improving denitrification efficiency.
[0018] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention are realized and obtained through the structures particularly pointed out in the description and the accompanying drawings.
[0019] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of this utility model, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1 This is a front view of the low-temperature flue gas denitrification device provided in an embodiment of this disclosure.
[0022] In the picture: 1. Flue gas duct; 2. Ammonia injection grille; 20. Atomizing nozzle; 3. Static mixer; 4. Electric louver; 40. Blade; 5. Baffle plate; 6. Flue gas rectifier; 7. Catalyst layer. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0024] In this document, when it is mentioned that a first component is located on a second component, this can mean that the first component can be directly formed on the second component, or that a third component can be inserted between the first and second components. Furthermore, in the accompanying drawings, the thickness of the components may be exaggerated or reduced for the purpose of effectively describing the technical content.
[0025] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.
[0026] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise expressly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.
[0027] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.
[0028] Research has shown that in the field of low-temperature flue gas denitrification technology, ammonia, as a reducing agent, undergoes selective catalytic reduction (SCR) with nitrogen oxides (NOx) in flue gas, which is a key process for achieving the harmless conversion of nitrogen oxides.
[0029] In existing technologies, ammonia mixing primarily relies on single-hole or multi-hole direct-injection nozzles of the ammonia injection grid to inject ammonia into the flue gas duct. However, this mixing method has significant drawbacks: First, after ammonia is injected, only a local mixing zone is formed near the injection point. The mixing path is short, and the contact time between ammonia and flue gas is insufficient, making it difficult to achieve sufficient turbulent mixing. Secondly, due to the significant density difference between ammonia and flue gas (ammonia density is approximately 0.77 kg / m³, while flue gas density is approximately 1.2 kg / m³), ammonia is prone to floating or flowing along the wall, resulting in uneven mixing.
[0030] This uneven mixing can lead to localized ammonia excess, increasing ammonia slip (typically exceeding 10 ppm). This not only increases ammonia consumption but can also cause corrosion in downstream equipment (such as air preheater blockage and catalyst poisoning), affecting denitrification efficiency (especially under low-temperature conditions, where reaction kinetics are slow and the requirements for mixing uniformity are even higher). Furthermore, while existing mixing devices such as static mixers can enhance turbulence, their mixing efficiency is often limited, and retrofitting requires adjustments to pipe dimensions, resulting in poor adaptability and high costs.
[0031] Therefore, how to solve the problem of uneven mixing of ammonia and flue gas is a technical problem that urgently needs to be solved in this field.
[0032] The defects in the above solutions and the reasons for their occurrence are the results of the inventors' practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure should be considered as the inventors' contributions to this disclosure.
[0033] It should be noted that similar labels and letters 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.
[0034] The following detailed description, with reference to the accompanying drawings, describes some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0035] like Figure 1 As shown, at least one embodiment provides a low-temperature flue gas denitrification device, comprising: The system comprises a flue gas duct 1, an ammonia injection grille 2, a static mixer 3, motorized louvers 4, a baffle plate 5, a flue gas rectifier 6, and a catalyst layer 7. These components work together to solve the industry problem of uneven mixing of ammonia and flue gas. The flue gas duct 1 is made of corrosion-resistant steel (such as Q235B), with a diameter that can be designed from 500-2000 mm depending on the actual operating conditions, and is used to transport the mixed airflow of flue gas and ammonia. Preferably, a flue gas flow sensor is installed inside the flue gas duct 1. The ammonia injection grille 2 is installed on the inner wall of the inlet end of the flue gas duct 1 and fixed by a flange connection to ensure that the ammonia injection point is located in the core area of the airflow. At least two sets of motorized louvers 4 are installed downstream of the static mixer 3; specifically, four sets of motorized louvers 4 are installed, with the air outlets of the four sets of motorized louvers 4 facing opposite directions to create cross-turbulence. The baffle plate 5 and the flue gas rectifier 6 are integrated on top of the low-temperature denitrification device (located below the flue gas rectifier 6 in the figure) to optimize the airflow. Catalyst layer 7 is arranged inside the low-temperature denitrification device to achieve the low-temperature denitrification reaction. The entire low-temperature denitrification device has a compact design and can directly modify the existing flue gas duct 1 without significant size adjustments, making it suitable for low-temperature flue gas treatment scenarios in industries such as steel and cement.
[0036] Reference Appendix Figure 1 The ammonia injection grille 2 includes multiple atomizing nozzles 20, each with an orifice diameter of 0.5-1.0 mm (preferably 0.8 mm) and an injection pressure of 0.1-0.3 MPa (preferably 0.2 MPa). Ammonia water (typically 20%-30% concentration) is atomized into micron-sized droplets (10-50 μm in diameter) through the nozzles and injected into the flue gas duct 1. The small orifice diameter and high pressure of the atomizing nozzles 20 ensure complete atomization of the ammonia water, rapid evaporation into ammonia gas, and reduced risk of excessively high local concentrations. The atomizing nozzles 20 are arranged in a matrix pattern with a spacing of 1 / 10 of the duct diameter to cover the entire airflow cross-section of the flue gas duct 1 and avoid dead zones.
[0037] Reference Appendix Figure 1 The static mixer 3, installed in the flue gas duct 1 downstream of the ammonia injection grid 2, consists of multiple twisted blades (not shown in detail in the figure, but preferably spiral-shaped). The twisted blades are made of 316L stainless steel, which is corrosion-resistant and has a long service life. Its working principle is to divide the mixed gas flow into multiple sub-flows by twisting the blades, generating rotation and shear effects, and forcing turbulent mixing. The twisting angle of the twisted blades in the static mixer 3 is 60°-90°, and the number of sub-flows is proportional to the number of twisted blades (usually 4-8 blades), ensuring that initial homogenization is achieved within a short distance (1-2 times the pipe diameter).
[0038] Continue to refer to the appendix Figure 1Four sets of motorized louvers 4 are evenly distributed along the axial direction of the flue gas duct 1. Each set of motorized louvers 4 contains multiple blades 40, and the tilt angle of the blades 40 is adjustable from 0° to 90°. The tilt angles of the blades 40 of adjacent sets of motorized louvers 4 are opposite. Controlled by an electric actuator (such as a servo motor), the tilt angles of the blades 40 of adjacent sets of louvers alternately change (for example, the first set of blades 40 has an angle of 30°, and the second set of blades 40 has an angle of 60°), forming a cross-flow with opposite airflow directions. This design generates a laterally mixed airflow, breaks the laminar boundary layer, and prolongs the mixing time of ammonia and flue gas to 1-3 seconds. The angle adjustment of the blades 40 is linked to the flue gas flow sensor to achieve adaptive control; for example, when the flow rate increases, the angle of the blades 40 automatically increases to enhance the disturbance and ensure stable mixing uniformity.
[0039] Continue to refer to the appendix Figure 1 The baffle 5 is installed at the top corner of the cryogenic denitrification device. It is an arc-shaped plate structure with a radius of curvature in ratio of 1:1.5 to the diameter of the flue gas duct 11 (for example, when the duct diameter is 1m, the radius of curvature is 0.67m). It is made of wear-resistant alloy with a smooth surface to reduce resistance. The baffle 5 guides the mixed flue gas smoothly into the device, avoiding energy loss and localized eddies caused by airflow impact.
[0040] Continue to refer to the appendix Figure 1 The flue gas rectifier 6 is located at the top of the low-temperature denitrification device and has a perforated plate structure with an opening ratio of 30%-50% (preferably 40%). The pores are evenly distributed with a diameter of 10-20mm, used to eliminate airflow turbulence and provide a uniform and stable airflow environment for the downstream catalyst layer 7 (flow velocity fluctuation controlled within ±5%). Experiments have verified that an opening ratio that is too low will increase resistance, while an opening ratio that is too high will result in insufficient rectification effect.
[0041] Continue to refer to the appendix Figure 1 A catalyst layer 7 is installed inside the flue gas duct 1, comprising at least three catalyst layers (three layers in this embodiment). Each catalyst layer is 100-200 mm thick (preferably 150 mm), with a layer spacing of 50-100 mm (preferably 75 mm). The catalyst is a low-temperature type, with an activity temperature range of 150-250°C. The multi-layer design extends the reaction path, increasing NOx conversion to over 90%; the layer spacing allows for gas flow redistribution, preventing blockage. Regular backflushing maintenance extends catalyst life.
[0042] The working principle is as follows: During operation, flue gas (temperature 150-250℃) enters the pipeline. Figure 1In the diagram, F1 indicates that flue gas enters flue gas duct 1; F2 indicates that ammonia water enters flue gas duct 1. The ammonia water is atomized and evaporated through the ammonia injection grid 2, and initially mixed with the flue gas. After the static mixer 3 enhances the turbulence, the electric louvers 4 generate cross disturbances through alternating angle changes, significantly improving the mixing uniformity. After being guided by the baffle 5 and evenly distributed by the flue gas rectifier 6, the mixed airflow enters the catalyst layer 7 for the SCR reaction. Figure 1 F3 is the flue gas outlet; F4 is the flue gas ash outlet.
[0043] Improved mixing efficiency: Compared to traditional single-hole injection, the mixing time is extended by 3 times, meeting the reaction time requirements of low-temperature denitrification. Reduced ammonia slip: Uniform mixing avoids localized ammonia excess, reducing ammonia consumption. Low retrofit cost: Modular design adapts to existing pipelines, reducing retrofit costs by more than 30%, suitable for upgrading older units. High degree of automation: Louvers are linked with sensors to achieve intelligent adjustment, reducing manual intervention.
[0044] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0045] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence unless expressly indicated herein. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed above may be referred to as the second element, component, region, layer, or segment.
[0046] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A low-temperature flue gas denitrification device, characterized in that, include: Flue gas duct (1), which is used to transport a mixed gas flow of flue gas and ammonia; Ammonia injection grille (2), which is installed at the inlet end of flue gas duct (1), is used to atomize ammonia water and inject it into the flue gas; A static mixer (3), which is installed in the flue gas duct (1) and located downstream of the ammonia injection grid (2), is used for forced turbulent mixing; At least two sets of motorized louvers (4) are installed in the flue gas duct (1) downstream of the static mixer (3), and the air outlets of the two sets of motorized louvers (4) are opposite. Baffle (5), which is installed at the top corner of the low-temperature denitrification device, is used to guide the mixed flue gas into the flow; The flue gas rectifier (6) is located at the top of the low-temperature denitrification device to eliminate airflow turbulence.
2. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The electric louvers (4) consist of four sets, which are evenly distributed along the axial direction of the flue gas duct (1), and the tilt angle of the blades (40) of each set of electric louvers (4) is adjustable.
3. The low-temperature flue gas denitrification device as described in claim 2, characterized in that, The blade (40) angle adjustment range of the electric louver (4) is 0° to 90°.
4. The low-temperature flue gas denitrification device as described in claim 2, characterized in that, The blades (40) of two adjacent electric louvers (4) alternately change their tilt angle and orientation to generate a transverse mixed airflow, extending the mixing time of ammonia and flue gas to 1-3 seconds.
5. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The static mixer (3) includes multiple twisted blades for splitting the mixed airflow into multiple sub-flows.
6. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The baffle (5) is an arc-shaped plate structure with a radius of curvature that is 1:1.5 the same as the diameter of the flue gas duct (1) to reduce airflow resistance.
7. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The flue gas rectifier (6) is a perforated plate structure with an opening rate of 30%-50%, used to uniformly distribute airflow.
8. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The flue gas duct (1) is provided with a catalyst layer (7), including at least three catalyst layers, each catalyst layer having a thickness of 100-200 mm and a layer spacing of 50-100 mm.
9. The low-temperature flue gas denitrification device as described in claim 1, characterized in that, The ammonia spraying grid (2) includes multiple atomizing nozzles (20), the atomizing nozzles (20) having an orifice diameter of 0.5-1.0 mm and a spray pressure of 0.1-0.3 MPa.