An ammonia injection grid for SCR denitration system

Abstract

The invention discloses an ammonia spraying grid for an SCR denitration system. Adjacent branch pipe assemblies on the ammonia spraying grid are arranged in a cross-staggered manner. The branch pipe assemblies on the same ammonia spraying grid are arranged in a layered manner with a high middle and low surroundings according to the characteristics of flue gas on the same cross section having a large flow velocity in the middle and a small flow velocity in the surroundings. This is beneficial to expanding the effective area of ​​ammonia spraying and making the ammonia react more evenly with NOx in the flue gas. A sharp upper cone is arranged on the nozzle of the branch pipe assembly, which can effectively break up large pieces of dust collapsed on the upper side. The smooth outer surface design of the upper cone makes it difficult for dust to deposit. A transverse blade and a longitudinal blade are arranged on the lower cone, which changes the ammonia flow from vertically upward to oblique rotation and diffusion at a certain angle, thereby strengthening the reaction of ammonia with NOx in the flue gas. X In addition, under the action of the telescopic rod and the lower vertebral body, the ammonia flow rate at the outlet of the branch pipe assembly can be adjusted and the nozzle can be effectively prevented from being blocked by dust accumulation.

Description

Technical Field

[0001] The invention relates to the technical field of power generation, in particular to an ammonia injection grid for an SCR denitration system. Background Art

[0002] With the continuous development of social economy, the consumption of traditional fossil energy is increasing day by day. In order to reduce the toxic and harmful gas emissions and damage caused by the consumption of traditional petrochemical energy, according to the latest "Boiler Air Pollutant Emission Standard" (GB 13271-2014), it is required that the nitrogen oxide emissions of boilers in use after April 1, 2017 should be ≤80mg / m 3 , the nitrogen oxide emissions of newly built boilers are ≤30mg / m3. By the end of 2019, the coal-fired power units that met the ultra-low emission limit were about 890 million kilowatts, accounting for about 86% of the total installed capacity of coal-fired power in the country, of which more than 80% were thermal power units using SCR denitrification technology. In order to ensure that the catalyst in the SCR denitrification system operates under the best temperature conditions, most SCR denitrification systems choose a high-temperature and high-dust layout, that is, the SCR denitrification system is arranged between the end of the boiler economizer and the air preheater.

[0003] In the SCR denitration system, in order to make the reducing agent such as NH3 more evenly mixed with the flue gas, an ammonia spraying grid is generally installed. The design of the ammonia spraying grid is to divide the flue cross section into several control areas, each control area has several nozzles, and the nozzle is the core component of the ammonia spraying grid. The layout of the high-temperature and high-dust SCR denitration system is conducive to saving investment and operating costs, but the disadvantage is that the flue gas contains a large amount of fly ash, which is easy to bond with the ammonium sulfate and ammonium bisulfate generated in the flue, and adhere to the surface of the equipment, causing some nozzles to be blocked, resulting in uneven distribution of ammonia and increased local ammonia escape. At present, the amount of ammonia sprayed on the ammonia spray grid branch pipe of the power plant is uneven, and the uniform distribution of flue gas and ammonia when entering the catalyst layer cannot be guaranteed, resulting in poor denitrification efficiency. Although the flow rate of each branch pipe can be controlled by adjusting the valve opening of the ammonia spray branch pipe, the amount of ammonia sprayed by different nozzles on the same ammonia spray branch pipe cannot be adjusted, so that the ammonia spray still cannot achieve the desired effect after adjustment. In addition, the outlet wind speed and wind direction of the ammonia spray grid nozzle and the time for mixing with the flue gas also have a great influence on the mixing effect of ammonia and flue gas.

[0004] However, the ammonia spray grids that can achieve dust prevention, flow adjustment, and enhanced mixing effects in the currently disclosed patents still have many shortcomings. The existing low-speed swirl wind cap and ammonia spray grid of the ammonia spray grid add a cap structure and a spiral airflow guide structure above the nozzle of the ammonia spray grid, which can change the ammonia flow from vertical upward to diagonal diffusion at a certain angle, reduce the vertical flow velocity of the ammonia flow to a certain extent, and increase the mixing time of the ammonia flow and the flue gas. However, this cap structure increases the accumulation of dust in the flue gas, which can easily cause the phenomenon of ash accumulation and collapse. In addition, the accumulated dust adheres to the ammonium sulfate and ammonium bisulfate generated by the side reactions in the flue gas, which will cause the dust accumulation at the edge of the nozzle to bridge, and the nozzle will be blocked during long-term operation. And the existing SCR flue gas denitrification ammonia spray grid anti-blocking nozzle prevents the collapse of the upper part of the grid from clogging the nozzle by setting a double-layer umbrella cover on the upper part of the tubular nozzle, but the protruding brim structure increases the flue gas contact area, does not take into account the wear problem of the umbrella cover, and the fixed wind direction of the ammonia outlet is not conducive to flexible operation.

[0005] An existing anti-blocking ammonia injection grid and SCR denitrification device adopts a spiral nozzle structure on the ammonia injection branch pipe. This structure can effectively prevent the ash accumulation above from collapsing. The ash accumulation can be broken up by the tip of the spiral nozzle and scattered around, thereby avoiding the problem of nozzle outlet blockage. However, this structure also reduces the mixing angle of ammonia and flue gas. The longitudinal section of the spiral nozzle in the structure reduces the ammonia outlet speed, which is not conducive to the mixing of flue gas and ammonia.

[0006] An existing ammonia spraying grid utilizes a rear control valve and a front control valve to control the ammonia spraying amount of the rear connecting pipe and the front connecting pipe respectively, so that each ammonia spraying head sprays an equal amount of ammonia. This structure improves the disadvantage of uneven ammonia spraying amount on the branch pipe of the previous ammonia spraying grid, but does not have a good effect on the quantitative control of the ammonia spraying amount. Spraying too little ammonia can easily cause the denitrification index to fail to meet the standard. Spraying too much ammonia will not only increase the operating cost but also cause side reactions, which will have an adverse effect on downstream equipment. In addition, this patent does not consider the impact of dust on the ammonia spraying grid in the nozzle design.

[0007] Therefore, it is of great practical significance for the safe and stable operation of the SCR denitrification system to study an ammonia injection grid that can prevent dust in the flue gas from clogging the ammonia injection branch pipe, flexibly adjust the ammonia injection flow rate, and enhance the mixing effect of ammonia and flue gas. Summary of the invention

[0008] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0009] In view of the above and / or existing problems in the existing ammonia injection grid for SCR denitration system, the present invention is proposed.

[0010] Therefore, the problem to be solved by the present invention is how to solve the problem of blockage of the ammonia injection branch pipe and adjustment of the ammonia injection flow rate.

[0011] In order to solve the above technical problems, the present invention provides the following technical solutions: an ammonia injection grid for an SCR denitration system, comprising:

[0012] A branch pipe assembly is arranged on a main pipe assembly below the branch pipe assembly through a connecting pipe, a control valve is arranged at one end of the main pipe assembly, and the branch pipe assembly is arranged in a "U" shape;

[0013] The branch pipe components are evenly and evenly distributed on the upper surface of the branch pipe components in a cross-staggered manner at equal intervals, and are arranged in high and low layers.

[0014] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, wherein: a cone assembly is provided on the branch pipe assembly, and the cone assembly is provided with an upper cone and a lower cone, the upper cone is conical, the upper part is a pointed end, the diameter of the lower circular surface is larger than the pipe diameter of the branch pipe assembly, and a circular hole is provided at the bottom, the inner surface of the circular hole is provided with a threaded groove, and the lower cone is arranged below the upper cone through a cylindrical shaft.

[0015] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, a bearing is also provided at the bottom of the upper vertebral body, the outer diameter of the bearing is smaller than the diameter of the lower circular surface of the upper vertebral body, and the inner diameter of the bearing is larger than the diameter of the circular hole, and the bearing is sleeved in the circular hole.

[0016] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, the lower cone includes an impeller shaft, a connecting piece is provided above the impeller shaft, transverse blades are provided on the circumferential surface of the impeller shaft, a cylindrical boss is provided below the impeller shaft, and longitudinal blades are provided below the cylindrical boss.

[0017] As a preferred solution of the ammonia injection grid for the SCR denitration system of the present invention, telescopic rods are arranged in an annular shape with equal intervals on the inner circle of the bearing, and the upper vertebral body and the lower vertebral body are hinged through the telescopic rods and the connecting piece.

[0018] As a preferred solution of the ammonia injection grid for the SCR denitration system of the present invention, the diameter of the cylindrical protrusion is smaller than the inner diameter of the nozzle of the branch pipe assembly.

[0019] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, one end of the cylindrical shaft is provided with a thread, the other end is provided with a spring, and the end provided with the spring is also fixedly connected to a truncated cone, and the upper surface diameter of the truncated cone is larger than the pipe diameter of the longitudinal blade.

[0020] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, one end of the cylindrical shaft provided with a thread is threadedly connected to the circular hole, the middle part of the cylindrical shaft is fitted with the lower cone, and the lower part is provided with an end of the truncated cone placed inside the branch pipe assembly.

[0021] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, a support frame is further provided between the branch pipe assembly and the upper vertebral body, and the support frames are three in number and are distributed on the branch pipe assembly and the upper vertebral body at equal intervals in a circular shape.

[0022] As a preferred solution of the ammonia injection grid for the SCR denitrification system described in the present invention, the lower vertebral body reciprocates up and down along the cylindrical axis through the telescopic rod, the minimum length of the telescopic rod should ensure that the upper vertebral body is not in contact with the lower vertebral body, and the maximum length of the telescopic rod should ensure that the lower surface of the cylindrical protrusion is in contact with the nozzle of the branch pipe assembly.

[0023] The beneficial effects of the present invention are as follows: the ammonia spraying grid of the SCR denitration system provided by the present invention is provided with a branch pipe assembly, the spiral directions of the longitudinal blades above the adjacent branch pipe assemblies on the same branch pipe assembly are different, and the adjacent branch pipe assemblies are arranged in a cross-staggered manner and in a layered arrangement with a high middle and low surroundings, which is beneficial to expanding the effective area of ​​ammonia spraying and making the reaction of ammonia with NOx in the flue gas more uniform. A cone assembly is provided, wherein the tip design of the upper cone can effectively puncture the influence of large pieces of ash on the nozzle when the ash above collapses, and the surface of the upper cone is smooth, which can reduce the deposition of ash, effectively prevent equipment clogging, and extend the service life of the equipment. The lower cone is controlled by the telescopic rod to control the ammonia spray flow rate of a single nozzle, which is beneficial to improve the linear fitting of the ammonia spray flow rate and the flue gas flow rate, realize accurate ammonia spraying, reduce the generation of ammonia spray by-products and reduce the denitration operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0025] Figure 1This is the overall structural diagram of the ammonia injection grid used in the SCR denitrification system.

[0026] Figure 2 This is a structural diagram of the cone assembly of the ammonia injection grid used in the SCR denitrification system.

[0027] Figure 3 This is a structural diagram of the upper vertebral body of the ammonia injection grid used in the SCR denitrification system.

[0028] Figure 4 This is a structural diagram of the lower vertebral body of the ammonia injection grid used in the SCR denitrification system.

[0029] Figure 5 This is a diagram of the cylindrical shaft structure of the ammonia injection grid used in the SCR denitrification system. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] Reference Figure 1 , which is the first embodiment of the present invention, and provides an ammonia injection grid for an SCR denitration system. The ammonia injection grid for the SCR denitration system includes a branch pipe assembly 100 and a branch pipe assembly 200, wherein the branch pipe assembly 100 is arranged on a main pipe assembly 200 below the branch pipe assembly 100 through a connecting pipe 110, a control valve 210 is provided at one end of the main pipe assembly 200, and the branch pipe assembly 100 is arranged in a "U" shape;

[0035] The branch pipe components 300 are evenly and evenly distributed on the upper surface of the branch pipe component 100 in a cross-staggered manner and arranged in high and low layers.

[0036] Based on the above, the branch pipe assembly 100 is arranged in a "U" shape, and a connecting pipe 110 is vertically arranged below the branch pipe assembly 100. Preferably, there are four connecting pipes 110, which connect the main pipe assembly 200 with the branch pipe assembly 100. The main pipe assembly 200 is arranged in parallel with the branch pipe 100. The main pipe assembly 200 is equipped with a control valve 210, and the control valve 210 is used to control the flow rate of ammonia. A plurality of branch pipe assemblies 300 are arranged on the branch pipe assembly 100, and adjacent branch pipe assemblies 300 are arranged in a cross-staggered manner. The branch pipe assembly 100 on the same ammonia injection grid is arranged according to the characteristics that the flue gas flow rate in the middle is large and the flow rate around is small on the same cross section. The branch pipe assembly 100 on the ammonia injection grid is arranged in a layered manner with a high middle and a low surrounding, which is beneficial to expand the effective area of ​​ammonia spraying and make ammonia and NO in the flue gas. X The reaction is more uniform.

[0037] Example 2

[0038] Reference Figures 2 to 5 , which is the second embodiment of the present invention, and is different from the first embodiment in that: a vertebral body assembly 400 is provided on the branch pipe assembly 300, and the vertebral body assembly 400 is provided with an upper vertebral body 410 and a lower vertebral body 420. The upper vertebral body 410 is conical, with a pointed tip at the top, and a diameter of the lower circular surface is larger than the pipe diameter of the branch pipe assembly 300, and a circular hole 411 is provided at the bottom, and a threaded groove is provided on the inner surface of the circular hole 411. The lower vertebral body 420 is arranged below the upper vertebral body 410 through a cylindrical shaft 430.

[0039] Based on the above, the outer surface of the upper cone 410 is smooth and the top is sharp, which can effectively break up the large dust that collapses above, and the smooth outer surface design makes it difficult for dust to accumulate, effectively preventing the equipment from being blocked, thereby extending the service life of the equipment, and the upper cone 410 and the lower cone 420 are connected by a cylindrical shaft 430, and the cylindrical shaft 430 is threaded through the circular hole 411 at the bottom of the upper cone 410, which has a simple and reliable structure and low manufacturing cost. The manufacturing material source is wide, no external power transmission is required, and the application range is wide.

[0040] Furthermore, a bearing 412 is provided at the bottom of the upper vertebral body 410. The outer diameter of the bearing 412 is smaller than the diameter of the lower circular surface of the upper vertebral body 410, and the outer circle of the bearing 412 is welded and fixed to the upper vertebral body 410. The inner diameter of the bearing 412 is larger than the diameter of the circular hole 411. A steel ball is provided between the outer circle and the inner circle of the bearing 412, so the inner circle of the bearing 412 can rotate flexibly, that is, the bearing 412 is sleeved in the circular hole 411. When the bearing 412 rotates, the circular hole 411 rotates with the rotation of the bearing 412, and the rotation transmission of the lower vertebral body 420 is transmitted through the bearing 412.

[0041] Preferably, the lower cone 420 includes an impeller shaft 421, a connecting piece 424 is provided above the impeller shaft 421, a transverse blade 422 is provided on the circumferential surface of the impeller shaft 421, a cylindrical protrusion 425 is provided below the impeller shaft 421, the diameter of the cylindrical protrusion 425 is smaller than the inner diameter of the nozzle of the branch pipe assembly 300, and a longitudinal blade 423 is provided below the cylindrical protrusion 425.

[0042] The transverse blades 422 will generate rotational motion under the drive of flue gas. Since the impeller shaft 421 is connected to the cylindrical protrusion 425, and the cylindrical protrusion 425 is connected to the longitudinal blades 423, when driven by flue gas, the transverse blades 422 rotate, thereby driving the longitudinal blades 423 to rotate. Moreover, since the spiral directions of the longitudinal blades 423 above the adjacent branch pipe assemblies 300 on the same branch pipe assembly 100 are different, the adjacent branch pipe assemblies 300 are cross-staggered, so that the ammonia flow changes from a vertical upward direction to an oblique rotational diffusion with a certain angle. After the ammonia is sprayed from the nozzle, the flow direction is more uniform, which increases the mixing time of the ammonia flow and the flue gas, expands the effective area of ​​ammonia spraying, and strengthens the ammonia and NO in the flue gas. X of mixed effects.

[0043] Based on the above, one end of the cylindrical shaft 430 is provided with a thread, which cooperates with the thread groove in the circular hole 411 in the upper vertebral body 410, and then is threadedly connected, so that the cylindrical shaft 430 is fixedly connected to the upper vertebral body 410, and the surface of the other end of the cylindrical shaft 430 is provided with a spring 431, and the end provided with the spring 431 is also fixedly connected to a cone 432. The upper surface diameter of the cone 432 is larger than the tube diameter of the longitudinal blade 423, so the setting of the spring 431 can reduce the impact force of the longitudinal blade 423 on the cone 432 when it moves downward.

[0044] Furthermore, the middle part of the cylindrical shaft 430 is fitted with the lower vertebral body 420, and one end of the lower part provided with a truncated cone 432 is placed inside the branch pipe assembly 300. A support frame 500 is also provided between the branch pipe assembly 300 and the upper vertebral body 410. There are three support frames 500, which are distributed on the branch pipe assembly 300 and the upper vertebral body 410 in an annular manner with equal intervals, so that the upper vertebral body 410 is completely fixed, that is, the lower vertebral body 420 can realize up and down reciprocating motion along the cylindrical shaft 430.

[0045] Specifically, telescopic rods 413 are arranged in a ring at equal intervals on the inner circle of the bearing 412, and the upper vertebral body 410 and the lower vertebral body 420 are hinged by the telescopic rods 413 and the connecting piece 424. The minimum length of the telescopic rod 413 should ensure that the upper vertebral body 410 and the lower vertebral body 420 are not in contact, and the maximum length of the telescopic rod 413 should ensure that the lower surface of the cylindrical protrusion 425 is in contact with the nozzle of the branch pipe assembly 300.

[0046] When the ammonia injection grid is working, the telescopic rod 413 can accurately control the movement of the lower vertebral body 420 under remote control, and control the ammonia injection flow rate of a single nozzle by moving the relative distance with the branch pipe assembly 300, which is beneficial to improve the linear fit of the ammonia injection flow rate and the flue gas flow rate, realize precise ammonia injection, reduce the generation of ammonia injection by-products and reduce the denitrification operating cost; when the ammonia injection grid stops working, the lower vertebral body 420 moves downward in the axial direction under the action of gravity until it completely covers the nozzle pipe mouth, even during the shutdown soot blowing period, the influence of dust on the nozzle can be completely avoided, thereby effectively preventing the equipment from being blocked.

[0047] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0048] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0049] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An ammonia injection grid for an SCR denitration system, characterized by: include, A branch pipe assembly (100), a main pipe assembly (200) arranged below the branch pipe assembly (100) via a connecting pipe (110), a control valve (210) being provided at one end of the main pipe assembly (200), and the branch pipe assembly (100) being arranged in a "U" shape; The branch pipe components (300) are evenly and evenly distributed on the upper surface of the branch pipe component (100) in a cross-staggered manner at equal intervals, and are arranged in high and low layers; The branch pipe assembly (300) is provided with a cone assembly (400), the cone assembly (400) being provided with an upper cone (410) and a lower cone (420), the upper cone (410) being conical, with a pointed tip at the top, a lower circular surface having a diameter greater than the pipe diameter of the branch pipe assembly (300), and a circular hole (411) being provided at the bottom, a threaded groove being provided on the inner surface of the circular hole (411), and the lower cone (420) being provided below the upper cone (410) via a cylindrical shaft (430); The lower cone (420) comprises an impeller shaft (421), a connecting piece (424) is provided above the impeller shaft (421), a transverse blade (422) is provided on the circumferential surface of the impeller shaft (421), a cylindrical protrusion (425) is provided below the impeller shaft (421), and a longitudinal blade (423) is provided below the cylindrical protrusion (425); The outer surface of the upper cone (410) is smooth; The transverse blades (422) will generate a rotational motion when driven by smoke, thereby driving the longitudinal blades (423) to rotate.

2. The ammonia injection grid for the SCR denitration system according to claim 1, characterized in that: A bearing (412) is also provided at the bottom of the upper cone (410); the outer diameter of the bearing (412) is smaller than the diameter of the lower circular surface of the upper cone (410); and the inner diameter of the bearing (412) is larger than the diameter of the circular hole (411); the bearing (412) is sleeved in the circular hole (411).

3. The ammonia injection grid for the SCR denitration system according to claim 2, characterized in that: Telescopic rods (413) are arranged in an annular pattern at equal intervals on the inner circle of the bearing (412), and the upper cone (410) and the lower cone (420) are hingedly connected via the telescopic rods (413) and the connecting piece (424).

4. The ammonia injection grid for the SCR denitration system according to claim 1, characterized in that: The diameter of the cylindrical protrusion (425) is smaller than the inner diameter of the nozzle of the branch pipe assembly (300).

5. The ammonia injection grid for the SCR denitration system according to claim 1, characterized in that: One end of the cylindrical shaft (430) is provided with a thread, and the other end is provided with a spring (431), and the end provided with the spring (431) is also fixedly connected to a truncated cone (432), and the diameter of the upper surface of the truncated cone (432) is larger than the diameter of the longitudinal blade (423).

6. The ammonia injection grid for the SCR denitration system according to claim 5, characterized in that: One end of the cylindrical shaft (430) provided with a thread is threadably connected to the circular hole (411), the middle portion of the cylindrical shaft (430) is sleeved with the lower cone (420), and one end of the lower portion provided with the truncated cone (432) is placed inside the branch pipe assembly (300).

7. The ammonia injection grid for the SCR denitration system according to claim 1, characterized in that: A support frame (500) is further provided between the branch pipe assembly (300) and the upper cone (410), and there are three support frames (500) which are distributed in an annular manner at equal intervals on the branch pipe assembly (300) and the upper cone (410).

8. The ammonia injection grid for the SCR denitration system according to claim 3, characterized in that: The lower cone (420) reciprocates up and down along the cylindrical axis (430) via the telescopic rod (413); the minimum length of the telescopic rod (413) ensures that the upper cone (410) and the lower cone (420) are not in contact, and the maximum length of the telescopic rod (413) ensures that the lower surface of the cylindrical protrusion (425) is in contact with the nozzle of the branch pipe assembly (300).

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