Device and method for removing large-particle fly ash in flue gas before SCR (Selective Catalytic Reduction) denitration

Abstract

The invention discloses a device and a method for removing large-particle fly ash in flue gas before SCR (Selective Catalytic Reduction) denitration. The device comprises a plurality of monomer structures, each single structure comprises a front rectifying plate, a guide plate and an ash collecting groove which are sequentially connected end to end, the front rectifying plate is parallel to the axial direction of the flue, the guide plate is horizontally inclined to the flowing direction of flue gas, the ash collecting groove is formed in the side face of the tail end of the guide plate, an opening faces the coming direction of the flue gas, and the top and the bottom of the ash collecting groove are open; the multiple single structures are arranged in an array mode, the single structure flow guide plates in the same row are arranged in parallel at intervals, and the single structure dust collecting grooves in the same column communicate with one another. The large-particle fly ash removing device can effectively remove large-particle fly ash before SCR denitration, is simple in structure and remarkable in effect, and has good application and popularization value.

Description

Technical Field

[0001] The invention belongs to the field of SCR denitration, and relates to a device and method for removing large particle fly ash from flue gas before SCR denitration. Background Art

[0002] In recent years, as domestic thermal power units generally burn high-ash low-quality coal, the ash accumulation and wear problems of SCR denitrification devices have become increasingly prominent. The ash accumulation and wear problems in SCR denitrification devices are important factors affecting their performance and life. These problems are usually closely related to the high-temperature, high-dust operating environment and the unevenness of the flow field. The causes of ash accumulation include: the ash content in the flue gas is higher than the design value, or the flow rate is too low, which will increase the deposition of ash in the SCR reactor. The fluctuation of the unit load will cause the fluctuation of the flue gas flow field, resulting in excessive instantaneous ash and causing ash accumulation.

[0003] Ash accumulation will cover the surface of the catalyst, reduce its catalytic activity, and lead to a decrease in denitrification efficiency. Ash accumulation will change the flow characteristics of the flue gas, aggravate the unevenness of the flow field, and further promote the formation of ash accumulation. Large particles in the ash accumulation will cause scouring and wear on the catalyst and the inner wall of the reactor. The uneven distribution of the flue gas flow field leads to excessively high or low local flue gas flow rates, causing scouring or deposition wear on the catalyst. The smoke content in the flue gas is too high, especially the scouring effect of large particles on the catalyst, which aggravates the wear. Wear will accelerate the deactivation and failure of the catalyst and shorten its service life. The catalytic activity of the worn catalyst is reduced, resulting in a decrease in denitrification efficiency. Even if the catalyst is replaced in time, frequent catalyst replacement and maintenance will increase the operating cost of the SCR denitrification device.

[0004] At present, there are some coarse fly ash pre-removal technologies in China, mainly arranging dense ash collection devices in the economizer outlet area to separate and collect coarse ash particles through special flow field structures. The above technologies mainly have problems such as complex structure, large device load, large transformation work volume, and complex construction. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a device and method for removing large particle fly ash from flue gas before SCR denitrification, which can effectively remove large particle fly ash before SCR denitrification, has a simple structure, significant effect, and has good promotion and application value.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A device for removing large-particle fly ash from flue gas before SCR denitration, comprising a plurality of monomer structures; Each single structure includes a front rectifying plate, a guide plate and an ash collecting groove connected in sequence from head to tail. The front rectifying plate is parallel to the axial direction of the flue, the guide plate is arranged horizontally and inclined to the direction of the flue gas flow, and the ash collecting groove is arranged on the side of the end of the guide plate, with its opening facing the direction of the flue gas, and the top and bottom are open; Multiple monomer structures are arranged in an array, guide plates of the monomer structures in the same row are arranged in parallel with gaps, and ash collecting troughs of the monomer structures in the same column are interconnected.

[0007] Preferably, a rear rectifying plate is connected to the end of the guide plate, and the rear rectifying plate is parallel to the axial direction of the flue.

[0008] Preferably, the gap width between horizontally adjacent single structures is greater than twice the width of the ash collecting groove.

[0009] Preferably, adjacent monomer structures in the same row are arranged in left-right mirror symmetry.

[0010] Preferably, the length of the front fairing is 0.3-0.5 m.

[0011] Preferably, the angle between the guide plate and the flue gas flow direction is 30-45°, and the projection width of the guide plate in the flue gas flow direction is 0.4-0.6 m.

[0012] Preferably, the ash collecting trough has a width of 0.15-0.25 m and a depth of 0.3-0.4 m.

[0013] Preferably, the height of the monomer structure is 0.4-0.8 m.

[0014] Preferably, the ash collecting chute adopts a C-shaped structure.

[0015] A method for removing large fly ash particles from a large fly ash particle removal device for flue gas before SCR denitrification is provided. The large fly ash particle removal device for flue gas before SCR denitrification is placed in a horizontal flue, wherein a front rectifier plate rectifies incoming flue gas, and after the rectified flue gas is guided by a guide plate, the guide plate is inclined and the large fly ash particles in the flue gas have a large inertia, so the large fly ash particles are enriched near the surface of the guide plate and flow along the surface of the guide plate. The large fly ash particles enriched at the end of the guide plate are subjected to inertia force, enter an ash collecting trough, collide and rub against the wall of the ash collecting trough, and settle due to gravity in the vertically arranged ash collecting trough, and the flue gas continues to flow downstream after flowing through the ash collecting trough area.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The front rectifying plate of the present invention is used to rectify the incoming flue gas, and the flue gas that may originally have unfavorable factors such as uneven velocity distribution and turbulence is initially rectified. After the rectified flue gas is guided by the guide plate, since the guide plate is inclined and the large particles of fly ash in the flue gas have a large inertia, the flue gas will be guided and enriched near the surface of the guide plate, flowing along the surface of the guide plate. The large particles of fly ash enriched at the end of the guide plate are affected by the inertia force and enter the ash collecting trough, and then collide and rub with the wall of the ash collecting trough to be captured, and settle by gravity in the vertically arranged ash collecting trough, thereby playing the role of enriching and removing large particles of fly ash, with a simple structure and significant effect.

[0017] Furthermore, the main function of the rear rectifier plate is to restore the uniformity of the flue gas flow field after passing through the ash collecting trough, ensure the stability of the downstream flue gas flow field, and provide a uniform reaction environment for the SCR denitrification reaction.

[0018] Furthermore, the gap width is greater than twice the width of the ash collecting trough, which can ensure that the rest of the flue gas can circulate normally without causing serious flow field obstruction due to the arrangement of the single structure.

[0019] Furthermore, adjacent monomer structures in the same row are arranged in left-right mirror symmetry to form an X-cross structure, which can stratify the flue gas for cross-flow turbulence and enhance mixing between flue gases, and can effectively reduce the NOx concentration and temperature deviation of the flue gas before the SCR, thereby improving the denitrification operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the horizontal arrangement of the monomer structure of the present invention; Figure 2 It is a schematic diagram of the upper and lower arrangement of the monomer structure of the present invention; Figure 3 A top view of the device for removing large-particle fly ash from flue gas before SCR denitration of the present invention; Figure 4 It is a schematic diagram of the monomer structure size of the present invention.

[0021] Among them: 1-front rectifying plate; 2-guide plate; 3-ash collecting trough; 4-rear rectifying plate. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" used in this article includes any and all combinations of one or more related listed items. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0026] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0027] The device for removing large-particle fly ash from flue gas before SCR denitrification of the present invention is used to efficiently capture and remove large-particle fly ash in the flue gas in the horizontal flue before the inlet of the SCR reactor, thereby achieving effective separation and removal of large-particle fly ash in the flue gas, significantly optimizing the quality of the flue gas entering the SCR reactor, thereby improving the denitrification efficiency of the SCR system, extending the service life of the catalyst, and reducing the system operation cost.

[0028] Example 1 like Figure 1-3 As shown, the device for removing large-particle fly ash from flue gas before SCR denitrification of the present invention includes multiple monomer structures, which are arranged in a reasonable array to form a fly ash capture system covering the entire flue cross section.

[0029] like Figure 1 As shown, the core components of each single structure include a vertically arranged front fairing 1, a guide plate 2, an ash collecting trough 3 and a rear fairing 4, and the front fairing 1, the guide plate 2 and the rear fairing 4 are connected end to end in a front to back order.

[0030] The front rectifying plate 1 is arranged at the front end of the single structure, parallel to the flue axis, and its main function is to rectify the flue gas entering the device. Through the action of the front rectifying plate 1, the flue gas that may have unfavorable factors such as uneven velocity distribution and turbulence is initially rectified, ensuring that the subsequent guide plate 2 can play the best effect in a uniform and stable flue gas flow field. In addition, the front rectifying plate 1 can also play a certain screening role, bringing some fly ash with smaller particle size and not easy to settle into the subsequent device or passing it directly, avoiding unnecessary burden on the ash collection trough 3.

[0031] The guide plate 2 is the most critical component in the single structure. It is set behind the front rectifier plate 1 and has a certain horizontal inclination angle with the flue gas flow direction. The main function of this plate is to guide the flue gas, change the local flow direction and velocity distribution of the flue gas, use the dynamic characteristics of the flue gas to guide the flue gas to flow along a predetermined path, and cause large particles of fly ash to gradually accumulate on the surface of the guide plate 2 due to inertia differences. Since large particles of fly ash have a large inertia and cannot change direction quickly with the airflow, when passing through the guide plate 2, these fly ashes will gradually enrich near the surface of the guide plate 2 and flow along the direction of the guide plate 2. The design angle and length of the guide plate 2 are optimized to ensure that large particles of fly ash can be effectively guided to the ash collection trough 3.

[0032] The ash collecting trough 3 is arranged on the end side of the guide plate 2, with its opening facing the direction of the flue gas, and the top and bottom are open to facilitate the large particles of fly ash to fall by gravity. When the large particles of fly ash in the flue gas are enriched to the end of the guide plate 2 under the action of the guide plate 2, these fly ashes enter the low-speed zone where the ash collecting trough 3 is located due to the action of inertia. In the low-speed zone, the fly ash collides and rubs against the wall of the ash collecting trough 3, further reducing its movement speed, and gradually settles to the bottom of the ash collecting trough 3 under the action of gravity. Finally, these large particles of fly ash enter the ash collecting device below (such as an ash hopper or other forms of dust collection devices) through the opening at the bottom of the ash collecting trough 3, achieving effective removal of large particles of fly ash.

[0033] The design shape of the ash collecting trough 3 can be adjusted according to the specific application scenario, for example, the horizontal cross section can be polygonal or semicircular, etc. In this embodiment, the ash collecting trough 3 adopts a C-shaped structure, which has good rigidity and anti-deformation ability, and can effectively capture and carry large particles of fly ash flowing from the guide plate 2.

[0034] The rear rectifier plate 4 is arranged after the ash collecting trough 3, parallel to the flue axial direction, and its main function is to restore the uniformity of the flue gas flow field after passing through the ash collecting trough 3. Since the setting of the ash collecting trough 3 will disturb the flow of downstream flue gas to a certain extent, resulting in adverse effects such as flow field deviation and increased turbulence, the rear rectifier plate 4 is arranged after the ash collecting trough 3 to reduce these adverse effects, ensure the stability of the downstream flue gas flow field, and provide a uniform reaction environment for the SCR denitration reaction.

[0035] The large particle fly ash removal device of the present invention achieves full coverage of the entire flue longitudinal section by arranging multiple monomer structures in an array in the vertical direction. Specifically, in the horizontal direction, the guide plates 2 of the monomer structures in the same row are arranged in parallel and evenly distributed according to the size of the flue to ensure that the flue gas can evenly pass through each monomer structure when entering the device. Figure 3As shown, in the vertical direction, the monomer structures are arranged in a staggered manner, that is, the guide directions of the monomer structure guide plates 2 of different heights in the same row are mirror-symmetrical with respect to the flue gas flow direction. This arrangement can further enhance the fly ash separation effect in the flue gas.

[0036] In this staggered arrangement, the upper and lower adjacent single-body structure ash collection slots 3 are interconnected to form a continuous dust collection channel, which can guide the large fly ash particles captured by the single-body structures at different heights to the same ash hopper or other dust collection device. This design not only simplifies the dust collection and cleaning process, but also avoids the secondary entrainment of fly ash in the system, thereby improving the overall fly ash removal efficiency.

[0037] In addition, the gap width between the horizontally adjacent monomer structures is carefully designed, usually not less than twice the width of the ash collecting trough 3, so as to ensure that the rest of the smoke can flow normally without causing serious flow field obstruction due to the arrangement of the monomer structures. At the same time, this arrangement forms multiple turbulent areas in the smoke, such as Figure 3 As shown, the upper and lower guide plates 2 form an X-cross structure, which further enhances the mixing effect of the flue gas, helps to reduce the NOx concentration and temperature deviation of the flue gas before the SCR system, and thus improves the overall operating conditions of the SCR reaction.

[0038] The large particle fly ash removal device of the present invention has significant technical advantages, which are mainly reflected in the following aspects: 1. Efficient fly ash removal effect: Through the reasonable design of the guide plate 2 and the ash collection trough 3, the device can effectively capture and remove large particles of fly ash in the flue gas, reduce the risk of wear and clogging of the SCR catalyst by these fly ashes, thereby extending the service life of the catalyst and improving the overall denitrification efficiency of the SCR system.

[0039] 2. Improve the uniformity of flue gas flow field: The front and rear rectifier plates 1 and 4 are arranged to ensure the uniformity of the flue gas flow field while avoiding the negative impact of the fly ash removal device on the flue gas flow. This is particularly important for the SCR system, as a uniform flow field helps the catalytic reaction to proceed fully and improves the NOx reduction efficiency.

[0040] 3. Modular design, strong adaptability: The modular design of the monomer structure makes the device have good adaptability and scalability. Whether it is a large flue or a small flue, the number and arrangement of the monomer structures can be adjusted to achieve efficient capture of large particles of fly ash. This flexibility enables the device of the present invention to be widely used in different types of industrial flue gas treatment scenarios.

[0041] 4. Low maintenance and operation costs: Since the device mainly relies on the natural flow of flue gas and the inertia and gravity of fly ash for removal, there are no complex mechanical moving parts, so the maintenance cost is low. At the same time, the efficient fly ash removal effect of the device also reduces the operating cost of the SCR system and further improves the economic benefits.

[0042] 5. Significant environmental protection and energy saving effects: By improving the denitration efficiency of the SCR system and reducing the loss of the catalyst, the present invention not only helps to reduce the NOx emissions in industrial flue gas, meeting the requirements of environmental protection regulations, but also indirectly saves energy consumption, and has significant environmental protection and energy-saving effects. like Figure 4 As shown, the length L of the single-structure front rectifying plate 1 in the present invention is generally 0.3-0.5m. The more drastic the flue turning or diameter change in the arrangement area of ​​the device, the longer L needs to be. CFD numerical simulation can also be used for optimization.

[0043] The angle x between the single structure guide plate 2 and the flue gas flow direction is generally 30-45°, and the projection width b of the guide plate 2 in the flue gas flow direction is generally 0.4-0.6m, where the width b is the spacing between the front rectifying plate 1 and the rear rectifying plate 4.

[0044] The ash collecting trough 3 is a C-shaped structure, and its width d is generally 0.15-0.25m, and its depth c should be 0.3-0.4m.

[0045] The rear straightening plate 4 is mainly used to improve the downstream flue gas flow field. Its length M is generally 0.2-0.5m and can be determined according to the downstream flow field design requirements.

[0046] The height of the single structure should be set to 0.4-0.8m, and the specific value can be evenly divided according to the height size of the installed flue.

[0047] The distance a between adjacent monomer structures in the horizontal direction is generally 0.5-1m.

[0048] Example 2 The operating principle of the above-mentioned SCR denitrification flue gas large particle fly ash removal device is as follows: the SCR denitrification flue gas large particle fly ash removal device is placed in the horizontal flue, wherein the front rectifier plate 1 is mainly used to rectify the incoming flue gas. After the rectified flue gas is diverted by the guide plate 2, due to the inclined setting of the guide plate 2 and the large particle fly ash in the flue gas has a large inertia, it will be enriched near the surface of the guide plate 2 and flow along the surface of the guide plate 2. The large particle fly ash enriched at the end of the guide plate 2 is subjected to the inertial force and enters the low-speed area at the ash collecting trough 3, and then collides and rubs with the wall of the ash collecting trough 3, and sinks into the ash collecting device (ash hopper or other structure) below in the vertically arranged ash collecting trough 3 by gravity. The flue gas continues to flow downstream after flowing through the ash collecting trough 3 area. In order to reduce the deflection and turbulence of the downstream flue gas flow field caused by the device, a rear rectifier plate 4 is set after the ash collecting trough 3 to improve the uniformity of the downstream flue gas flow field.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0050] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A device for removing large particles of fly ash from flue gas before SCR denitrification, characterized in that: including a plurality of monomer structures; Each single structure comprises a front flow straightening plate (1), a flow guide plate (2) and an ash collecting groove (3) which are connected end to end in sequence, the front flow straightening plate (1) is parallel to the axial direction of the flue, the flow guide plate (2) is arranged horizontally and inclined to the direction of the flue gas flow, and the ash collecting groove (3) is arranged on the side of the end of the flow guide plate (2), with its opening facing the direction of the flue gas, and the top and bottom are open; The plurality of monomer structures are arranged in an array in the vertical direction, the guide plates (2) of the monomer structures in the same row are arranged in parallel with gaps, and the ash collecting troughs (3) of the monomer structures in the same column are interconnected.

2. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The end of the guide plate (2) is connected to a rear rectifying plate (4), and the rear rectifying plate (4) is parallel to the axial direction of the flue.

3. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The width of the gap between horizontally adjacent single structures is greater than twice the width of the ash collecting groove (3).

4. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: Adjacent monomer structures in the same row are arranged in left-right mirror symmetry.

5. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The length of the front fairing (1) is 0.3-0.5m.

6. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The included angle between the guide plate (2) and the direction of the flue gas flow is 30-45 degrees, and the projection width of the guide plate (2) in the direction of the flue gas flow is 0.4-0.6 m.

7. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The ash collecting trough (3) has a width of 0.15-0.25 m and a depth of 0.3-0.4 m.

8. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The height of the single structure is 0.4-0.8m.

9. The device for removing large-particle fly ash from flue gas before SCR denitration according to claim 1 is characterized in that: The ash collecting trough (3) adopts a C-shaped structure.

10. A method for removing large particle fly ash from flue gas before SCR denitration based on the large particle fly ash removal device according to any one of claims 1 to 9, characterized in that: The large fly ash removal device for flue gas before SCR denitrification is placed in a horizontal flue, wherein a front rectifying plate (1) rectify the incoming flue gas, and after the rectified flue gas is guided by a guide plate (2), the guide plate (2) is inclined and the large fly ash particles in the flue gas have a large inertia, so the large fly ash particles are enriched near the surface of the guide plate (2) and flow along the surface of the guide plate (2). The large fly ash particles enriched at the end of the guide plate (2) are subjected to inertial force and enter the ash collecting trough (3), then collide and rub against the wall of the ash collecting trough (3), and settle in the vertically arranged ash collecting trough (3) due to gravity, and the flue gas continues to flow downstream after flowing through the ash collecting trough (3) area.

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