SCR (Selective Catalytic Reduction) denitration system

Abstract

The invention discloses an SCR (Selective Catalytic Reduction) denitration system which comprises an SCR denitration tower, and a flue guide plate, a flue gas pre-mixer, a main ammonia spraying grid, an ammonia-smoke turbulator, a main catalyst layer, a supplementary ammonia spraying grid and a supplementary catalyst layer are sequentially arranged in the SCR denitration tower in the flue gas circulation direction; the main ammonia spraying grid comprises a plurality of first ammonia spraying branch pipes which are arranged in parallel at equal intervals in the direction perpendicular to the flue gas circulation direction, a row of first nozzles and a row of second nozzles are obliquely arranged on each first ammonia spraying branch pipe in the length direction, the number of the nozzles in each row is multiple, and the first nozzles and the second nozzles are arranged in a staggered mode and face different directions; each ammonia spraying branch pipe is communicated with the ammonia supply pipe, and an ammonia gas control valve is arranged on each first ammonia spraying branch pipe. Through cooperative use of the main ammonia injection grid and the supplementary ammonia injection grid, ammonia escape is reduced, uniform injection of ammonia gas in the whole reaction space is realized, and it is ensured that ammonia escape is maintained at a reasonable level.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas denitration, and in particular relates to an SCR denitration system. Background Art

[0002] In order to reduce NOx emissions from coal-fired power generation, flue gas denitrification technology is currently a commonly used method. Among them, selective catalytic reduction (SCR) denitrification technology refers to the reaction of the reducing agent (ammonia) with nitrogen oxides in the flue gas under the action of a catalyst to generate harmless nitrogen and water, thereby removing NOx from the flue gas. The efficient and stable operation of SCR denitrification devices has attracted universal attention. In the existing SCR denitrification devices, an ammonia spray grid is horizontally arranged at a certain height in the flue, and the nozzle of the ammonia spray grid is arranged on the leeward side of the ammonia spray grid. Ammonia is sprayed into the flue gas along the flow direction of the flue gas, and the mixed gas and the flue gas react in the catalytic bin to achieve denitrification. However, in the process of catalytic reduction of NOx in the flue gas to N2, there is inevitably a certain amount of ammonia escape. When the ammonia escape level is too large, the escaped ammonia will form serious ammonium bisulfate blockage with SO3 in the flue gas at the cold end of the air preheater, which can easily cause blockage of the air preheater and adversely affect the downstream dust removal equipment, low-pressure economizer, etc. Therefore, it is necessary to develop a device that can improve the accuracy of ammonia spraying and reduce ammonia escape. Summary of the invention

[0003] In view of the deficiencies in the prior art, the object of the present invention is to provide an SCR denitration system to solve the technical problems in the prior art that the amount of ammonia escape from the denitration system is large and the SCR denitration system is easily blocked.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0005] An SCR denitration system comprises an SCR denitration tower, wherein a flue guide plate, a flue gas premixer, a main ammonia injection grid, an ammonia-smoke spoiler, a main catalyst layer, a supplementary ammonia injection grid and a supplementary catalyst layer are sequentially arranged in the SCR denitration tower along the flue gas flow direction;

[0006] The main ammonia injection grid comprises a plurality of first ammonia injection branch pipes which are arranged in parallel and at equal intervals perpendicular to the flue gas flow direction, each of which is provided with a row of first nozzles and a row of second nozzles obliquely along the length direction, each row of nozzles has a plurality of nozzles, and the first nozzles and the second nozzles are arranged alternately and in different directions;

[0007] Each of the ammonia injection branch pipes is connected to the ammonia supply pipe, and each of the first ammonia injection branch pipes is provided with an ammonia control valve.

[0008] The present invention also has the following technical features:

[0009] Specifically, anti-clogging nozzles are provided at the head ends of the first nozzle and the second nozzle.

[0010] Furthermore, air inlets and mixed gas outlets are respectively provided at both ends of the ammonia supply pipe, and at least one mounting hole is opened on the wall of the ammonia supply pipe, and an ammonia air supply pipe is passed through the mounting hole; the air inlet is connected to the air duct, and the mixed gas outlet is connected to the ammonia air inlet pipe.

[0011] Furthermore, the ammonia air supply pipe is provided with a plurality of ammonia air supply ports.

[0012] Furthermore, the supplementary ammonia injection grid comprises a plurality of second ammonia injection branch pipes arranged in parallel, each of the second ammonia injection branch pipes is provided with a plurality of third nozzles, and the third nozzles are arranged facing away from the flue gas flow direction.

[0013] Furthermore, the ammonia-smoke spoiler includes a base plate, a plurality of blade mounting holes are formed on the base plate, and the plurality of blade mounting holes are arranged at equal intervals in the longitudinal and transverse directions; spoiler blades are movably mounted in the blade mounting holes.

[0014] Furthermore, a flue gas inlet is provided at the top of the SCR denitrification tower, and a clean gas outlet is provided at the bottom of the SCR denitrification tower; the space inside the SCR denitrification tower constitutes a reaction chamber;

[0015] The reaction chamber between the flue gas inlet and the flue guide plate is a guide chamber, the reaction chamber between the flue guide plate and the flue gas premixer is a premixing chamber, the reaction chamber between the flue gas premixer and the main ammonia injection grid is the main ammonia injection warehouse, the reaction chamber between the main ammonia injection grid and the ammonia-smoke spoiler is a spoiler chamber, the reaction chamber between the ammonia-smoke spoiler and the main catalyst layer is the main catalytic warehouse, the reaction chamber between the main catalyst layer and the supplementary ammonia injection grid is the supplementary ammonia injection warehouse, the reaction chamber between the supplementary ammonia injection grid and the supplementary catalyst layer is the supplementary catalytic warehouse, and the reaction chamber between the supplementary catalyst layer and the clean gas outlet is the gas outlet warehouse; the flue gas inlet is sequentially connected with the guide chamber, the premixing chamber, the main ammonia injection warehouse, the spoiler chamber, the main catalytic warehouse, the supplementary ammonia injection warehouse, the supplementary catalytic warehouse, the gas outlet warehouse and the clean gas outlet.

[0016] Furthermore, the flue gas inlet is connected to an air intake pipe, the clean gas outlet is connected to an air outlet pipe, and the air intake pipe, the supplementary ammonia spraying tank and the air outlet pipe are all provided with NOx concentration detectors.

[0017] Furthermore, an ammonia detector is also provided in the gas outlet pipe.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] (1) The SCR denitration system of the present invention reduces ammonia slip by using a main ammonia injection grid and a supplementary ammonia injection grid in combination, realizes uniform injection of ammonia in the entire reaction space, and ensures that ammonia slip is maintained at a reasonable level, wherein the main ammonia injection grid is composed of a plurality of first ammonia injection branch pipes, and the ammonia flow rate in each first ammonia injection branch pipe can be adjusted individually, thereby realizing the adjustability of ammonia concentration on the same cross section in the SCR denitration tower; the conversion rate of NOx in flue gas is improved by using a main catalyst layer and a supplementary catalyst layer in combination, and the supplementary catalyst layer has a small thickness and a simple structure.

[0020] (2) In the SCR denitration system of the present invention, pure ammonia and dilution air are evenly mixed in the ammonia supply pipe, ensuring uniform distribution of ammonia concentration in the ammonia injection branch pipe, and an anti-wear and anti-clogging nozzle is provided on the ammonia nozzle, which can effectively protect the nozzle and achieve the effect of uniform flow and anti-clogging.

[0021] (3) The present invention adopts flue guide plates and flue gas premixers to evenly distribute the flue gas from upstream, which can improve the flue gas flow field, reduce the impact of operating condition changes on the NOx distribution in the flue cross section of the denitrification inlet, and improve the full load adaptability of the ammonia injection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the overall structure of the device of the present invention, wherein the arrow indicates the direction of smoke flow;

[0023] Figure 2 A schematic diagram of the three-dimensional structure of the main ammonia injection grid;

[0024] Figure 3 This is a schematic diagram of the partial structure of the main ammonia injection grid;

[0025] Figure 4 This is a schematic diagram of the ammonia supply pipe structure;

[0026] Figure 5 This is a rear view of the first ammonia injection branch pipe;

[0027] Figure 6 Schematic diagram of the ammonia-smoke spoiler structure.

[0028] The meanings of the numbers and symbols in the figure are:

[0029] 1-SCR denitration tower, 2-reaction chamber, 3-flue guide plate, 4-flue gas premixer, 5-main ammonia grid, 6-ammonia-smoke spoiler, 7-main catalyst layer, 8-supplementary ammonia grid, 9-supplementary catalyst layer, 10-ammonia control valve, 11-inlet pipe, 12-outlet pipe, 13-NOx concentration detector, 14-ammonia detector;

[0030] 101-smoke inlet, 102-clean gas outlet;

[0031] 201- flow guide chamber, 202- premixing chamber, 203- ammonia spraying chamber, 204- flow disturbance chamber, 205- main catalytic chamber, 206- supplementary ammonia spraying chamber, 207- supplementary catalytic chamber, 208- gas outlet chamber;

[0032] 501-first ammonia spraying branch pipe, 502-first nozzle, 503-second nozzle, 504-ammonia supply pipe, 505-ammonia air supply pipe, 506-anti-blocking nozzle;

[0033] 601-base plate, 602-blade mounting hole, 603-spoiler blade;

[0034] 801-second ammonia injection branch pipe, 802-third nozzle;

[0035] 5041-air inlet, 5042-mixed gas outlet, 5043-mounting hole;

[0036] 5051-Ammonia air supply vent.

[0037] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0038] It should be noted that all components and instruments in the present invention, unless otherwise specified, are components and instruments known in the art. For example, the flue guide plate adopts a conventional gas guide plate known in the prior art, such as a gas guide plate composed of multiple guide plates.

[0039] The flue gas premixer adopts a conventional gas premixer known in the prior art, also called a flue gas mixer.

[0040] NO X The concentration detection instrument adopts a conventional nitrogen oxide detector known in the prior art, and the ammonia detector also adopts a conventional ammonia detector known in the prior art. The ammonia control valve is a conventional gas control valve.

[0041] The terms "upper", "lower", "front", "back", "top", "bottom", etc. used in the present invention to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. "Inside" and "outside" refer to the inside and outside of the contour of the corresponding components, and the above terms should not be understood as limitations on the present invention.

[0042] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0043] In the absence of any contrary explanation, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0044] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0045] Example:

[0046] Following the above technical solution, Figure 1 As shown, this embodiment provides an SCR denitration system, including an SCR denitration tower 1, in which a flue guide plate 3, a flue gas premixer 4, a main ammonia injection grid 5, an ammonia-smoke spoiler 6, a main catalyst layer 7, a supplementary ammonia injection grid 8 and a supplementary catalyst layer 9 are sequentially arranged along the flue gas flow direction in the SCR denitration tower 1;

[0047] like Figure 2 , Figure 3 and Figure 5 As shown, the main ammonia injection grid 5 includes a plurality of first ammonia injection branch pipes 501 arranged in parallel at equal intervals perpendicular to the flue gas flow direction, and a row of first nozzles 502 and a row of second nozzles 503 are respectively arranged obliquely along the length direction on the pipe wall of the upper half of each first ammonia injection branch pipe 501, and the first nozzles 502 and the second nozzles 503 are arranged alternately and in different directions; the number of the first nozzles 502 and the second nozzles 503 are both multiple. In this embodiment, the first nozzle 502 is arranged obliquely toward the upper left, and the second nozzle 503 is arranged obliquely toward the upper right, and the angle formed by the projections of the first nozzle 502 and the second nozzle 503 in the same vertical plane is 30-150°, and spoilers are set on the first nozzle 502 and the second nozzle 503.

[0048] Each first ammonia injection branch pipe 501 is connected to an ammonia supply pipe 504 . The ammonia supply pipe 504 is used to introduce a mixture of ammonia and air into the ammonia supply pipe. Each first ammonia injection branch pipe 501 is provided with an ammonia control valve 10 .

[0049] In other schemes, the main ammonia injection grid 5 can be divided into multiple ammonia injection grid units, and the flow rate of ammonia in each ammonia injection grid unit can be adjusted by an independently arranged ammonia control valve 10, thereby completing the adjustment of the ammonia injection amount of each ammonia injection grid unit, so as to achieve the adjustment of the ammonia concentration at a certain cross-section above and below the main ammonia injection grid 5.

[0050] As a preferred solution of this embodiment, the head ends of the first nozzle 502 and the second nozzle 503 are both provided with anti-clogging nozzles 506 .

[0051] In this embodiment, a flue gas inlet 101 is provided at the top of the SCR denitration tower 1, and a clean gas outlet 102 is provided at the bottom of the SCR denitration tower; the space inside the SCR denitration tower 1 constitutes a reaction chamber 2, and the flue gas enters the SCR denitration tower 1 from the flue gas inlet 101 and moves along the flue gas flow direction, and the purified flue gas is discharged from the clean gas outlet 102. The flue guide plate 3 and the flue gas premixer 4 are mainly used to evenly distribute the flue gas from upstream, improve the flue gas flow field, and the flue gas flow velocity distribution deviation is not more than 15%. Preferably, the SCR denitration tower 1 is also connected to a cold air bypass, and the temperature of the flue gas entering the SCR denitration tower 1 is adjusted by inputting cold air and exchanging heat with the high-temperature flue gas, so that the operating temperature in the SCR denitration tower 1 is maintained at 320-420°C. The reaction of NOx and ammonia in the flue gas is carried out in the main catalyst layer 7 and the supplementary catalyst layer 9, and the main catalyst layer 7 and the supplementary catalyst layer 9 are filled with known conventional catalysts for denitration, such as catalysts with titanium dioxide as the main component. The main catalyst layer 7 is installed in a "2+1" manner, that is, the middle layer and the lower layer are initially installed, and the upper layer is reserved. The upper layer can be added according to the initial NOx concentration of the original flue gas and the denitrification efficiency. The supplementary catalyst layer 9 is installed as a single layer, and the supplementary catalyst layer 9 is used to further carry out the denitrification reaction to improve the denitrification efficiency.

[0052] The conversion rate of NOx in flue gas is improved by using the main catalyst layer and the supplementary catalyst layer in combination, and the supplementary catalyst layer is appropriately thinned and has a simple structure.

[0053] As a preferred solution of this embodiment, Figure 4 As shown, an air inlet 5041 and a mixed gas outlet 5042 are respectively provided at both ends of the ammonia supply pipe 504, and at least one mounting hole 5043 is also opened on the wall of the ammonia supply pipe 504, and an ammonia air supply pipe 505 is inserted into the mounting hole 5043; the air inlet 5041 is connected to an air duct, and the mixed gas outlet 5042 is connected to the first ammonia injection branch pipe 501. The ammonia supply pipe 504 extends to the outside of the SCR denitration tower 1 and is connected to the ammonia storage tank.

[0054] As a preferred solution of this embodiment, a plurality of ammonia air supply ports 5051 are provided on the ammonia air supply pipe 505. Ammonia in the ammonia air supply pipe 505 enters the ammonia supply pipe 504 through the ammonia air supply ports 5051, and is mixed with the air entering through the air inlet 5041 to obtain a mixed gas, and the mixed gas enters the first ammonia injection branch pipe 501 through the mixed gas outlet 5042.

[0055] As a preferred solution of this embodiment, the supplementary ammonia injection grid 8 includes a plurality of second ammonia injection branch pipes 801 arranged in parallel, each of which is provided with a plurality of third nozzles 802, and the third nozzles 802 are arranged facing away from the flue gas flow direction.

[0056] like Figure 6 As shown, as a preferred solution of this embodiment, the ammonia-smoke spoiler 6 includes a substrate 601, on which a plurality of blade mounting holes 602 are provided, and the plurality of blade mounting holes 602 are arranged at equal intervals along the longitudinal direction and the transverse direction; spoiler blades 603 are movably mounted in the blade mounting holes 602. The spoiler blades 603 can rotate 360 ​​degrees in the blade mounting holes 602, and can swing to both sides with the middle part as the axis.

[0057] As a specific solution of this embodiment, Figure 1 As shown, a flue gas inlet 101 is provided at the top of the SCR denitration tower 1, and a clean gas outlet 102 is provided at the bottom of the SCR denitration tower; the space inside the SCR denitration tower 1 constitutes a reaction chamber 2, the reaction chamber 2 between the flue gas inlet and the flue guide plate 3 is a guide chamber 201, the reaction chamber 2 between the flue guide plate 3 and the flue gas premixer 4 is a premixing chamber 202, the reaction chamber 2 between the flue gas premixer 4 and the main ammonia injection grid 5 is a main ammonia injection chamber 203, the reaction chamber 2 between the main ammonia injection grid 5 and the ammonia-smoke spoiler 6 is a spoiler chamber 204, and the reaction chamber 2 between the ammonia-smoke spoiler 6 and the main catalyst layer 7 is a spoiler chamber 205. The reaction chamber 2 between the main catalyst layer 7 and the supplementary ammonia injection grid 8 is the supplementary ammonia injection bin 206, the reaction chamber 2 between the supplementary ammonia injection grid 8 and the supplementary catalyst layer 7 is the supplementary catalytic bin 207, and the reaction chamber 2 between the supplementary catalyst layer 7 and the clean gas outlet is the gas outlet bin 208; the flue gas inlet 101 is sequentially connected with the guide bin 201, the premixing bin 202, the main ammonia injection bin 203, the turbulence bin 204, the main catalytic bin 205, the supplementary ammonia injection bin 206, the supplementary catalytic bin 207, the gas outlet bin 208 and the clean gas outlet 102.

[0058] As a preferred solution of this embodiment, the flue gas inlet 201 is connected to an air inlet pipe 11, the clean gas outlet 102 is connected to an air outlet pipe 12, and the air inlet pipe 11, the ammonia replenishing tank 206 and the air outlet pipe 12 are all provided with a NOx concentration detector 13. X The detector 13 can detect the NOx concentration at multiple measuring points and feed back the detection results to the connected control system. The control system controls the opening of the ammonia control valve 10 through pre-installed software to adjust the amount of ammonia injection to achieve NOx concentration in the flue gas. X Precise ammonia spraying.

[0059] As a specific solution of this embodiment, Figure 1 As shown, an ammonia detector 14 is also provided on the gas outlet pipe 12 .

[0060] The working process of the present invention mainly comprises the following steps:

[0061] Step 1, the flue gas enters the SCR denitrification tower 1 through the flue gas inlet 101, and the flue gas flows through the guide chamber 201, the flue guide plate 3, the premixing chamber 202 and the flue gas premixer 4 in sequence, and then enters the ammonia injection chamber 203 and the spoiler chamber 204;

[0062] Step 2, open the ammonia control valve, and the ammonia mixed with air enters the ammonia supply pipe, then flows into the first ammonia spray branch pipe 501, and then is sprayed into the ammonia spray bin 203 and the spoiler bin 204 through the first nozzle 502 and the second nozzle 503;

[0063] Step 3, the flue gas and ammonia are mixed in the ammonia spraying bin 203 and the turbulence bin 204, enter the main catalytic bin 205, and then react under the action of the catalyst to achieve primary denitration;

[0064] Step 4: After the flue gas after primary denitration enters the supplementary ammonia spraying bin 206, the ammonia mixed with air enters the second ammonia spraying branch pipe 801 and is sprayed out through the third nozzle 802; the ammonia mixed with air is mixed with the ammonia after primary denitration and enters the supplementary main catalytic bin 207; the reaction is carried out under the action of the catalyst in the supplementary catalyst layer 9 to achieve secondary denitration;

[0065] Step 5: The flue gas after secondary denitrification enters the gas outlet bin 208 and is finally discharged from the clean gas outlet 102.

[0066] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0067] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An SCR denitration system, comprising an SCR denitration tower (1), characterized in that: The SCR denitration tower (1) is provided with a flue guide plate (3), a flue gas premixer (4), a main ammonia injection grid (5), an ammonia-smoke spoiler (6), a main catalyst layer (7), a supplementary ammonia injection grid (8) and a supplementary catalyst layer (9) in sequence along the flue gas flow direction; The main ammonia injection grid (5) comprises a plurality of first ammonia injection branch pipes (501) arranged in parallel and at equal intervals perpendicular to the flue gas flow direction, each of the first ammonia injection branch pipes (501) being obliquely arranged along the length direction with a row of first nozzles (502) and a row of second nozzles (503), the first nozzles (502) and the second nozzles (503) being staggered and oriented in different directions; Each of the first ammonia injection branch pipes (501) is connected to the ammonia supply pipe (504), and each of the first ammonia injection branch pipes (501) is provided with an ammonia control valve (10).

2. The SCR denitration system according to claim 1, characterized in that: Anti-clogging nozzles (506) are provided at the head ends of the first nozzle (502) and the second nozzle (503).

3. The SCR denitration system according to claim 1, characterized in that: An air inlet (5041) and a mixed gas outlet (5042) are respectively provided at both ends of the ammonia supply pipe (504); at least one mounting hole (5043) is also provided on the wall of the ammonia supply pipe (504); an ammonia air supply pipe (505) is passed through the mounting hole (5043); the air inlet (5041) is connected to an air duct, and the mixed gas outlet is connected to the first ammonia injection branch pipe (501).

4. The SCR denitration system according to claim 3, characterized in that: The ammonia air supply pipe (505) is provided with a plurality of ammonia air supply ports (5051).

5. The SCR denitration system according to claim 4, characterized in that: The supplementary ammonia injection grid (8) comprises a plurality of second ammonia injection branch pipes (801) arranged in parallel, each of the second ammonia injection branch pipes (801) is provided with a plurality of third nozzles (802), and the third nozzles (802) are arranged facing away from the direction of flue gas flow.

6. The SCR denitration system according to claim 1, characterized in that: The ammonia-smoke spoiler (6) comprises a base plate (601), a plurality of blade mounting holes (602) are provided on the base plate (601), the plurality of blade mounting holes (602) are arranged at equal intervals in the longitudinal and transverse directions, and spoiler blades (603) are movably mounted in the blade mounting holes (602).

7. The SCR denitration system according to claim 1, characterized in that: The top of the SCR denitrification tower (1) is provided with a flue gas inlet (101), and the bottom of the SCR denitrification tower is provided with a clean gas outlet (102); the space inside the SCR denitrification tower (1) constitutes a reaction chamber (2); The reaction chamber (2) between the flue gas inlet and the flue guide plate (3) is a guide chamber (201), the reaction chamber (2) between the flue guide plate (3) and the flue gas premixer (4) is a premixing chamber (202), the reaction chamber (2) between the flue gas premixer (4) and the main ammonia injection grid (5) is a main ammonia injection chamber (203), the reaction chamber (2) between the main ammonia injection grid (5) and the ammonia-smoke turbulent device (6) is a turbulent chamber (204), the reaction chamber (2) between the ammonia-smoke turbulent device (6) and the main catalyst layer (7) is a main catalyst chamber (205), the main catalyst layer (7) and the supplementary ammonia injection grid are connected to the reaction chamber (203) and the main catalyst layer (205). The reaction chamber (2) between the grids (8) is a supplementary ammonia spraying chamber (206), the reaction chamber (2) between the supplementary ammonia spraying grid (8) and the supplementary catalyst layer (7) is a supplementary catalytic chamber (207), and the reaction chamber (2) between the supplementary catalyst layer (7) and the clean gas outlet is a gas outlet chamber (208); the flue gas inlet (101) is sequentially connected to the guide chamber (201), the premixing chamber (202), the main ammonia spraying chamber (203), the turbulence chamber (204), the main catalytic chamber (205), the supplementary ammonia spraying chamber (206), the supplementary catalytic chamber (207), the gas outlet chamber (208) and the clean gas outlet (102).

8. The SCR denitration system according to claim 7, characterized in that: The flue gas inlet (201) is connected to an air intake pipe (11), the clean gas outlet (102) is connected to an air outlet pipe (12), and the air intake pipe (11), the ammonia replenishing spray tank (206) and the air outlet pipe (12) are all provided with a NOx concentration detector (13).

9. The SCR denitration system according to claim 8, characterized in that: The gas outlet pipe (12) is also provided with an ammonia detector (14).

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