A smoke and air duct structure and denitrification system adapted to a semi-inclined rectifier grid

Abstract

The present invention discloses a smoke duct structure and a denitrification system adapted to a semi-inclined rectifying grid. In the smoke duct structure, a first guide component and a second guide component are provided at the end of the smoke duct inlet. The first guide component is used to uniformly guide the smoke in the low-level smoke duct in the smoke duct inlet into the inclined section rectifying grid; the second guide component is used to uniformly guide the smoke in the high-level smoke duct in the smoke duct inlet into the horizontal section rectifying grid of the semi-inclined rectifying grid. This structure of the present invention can make the smoke volume and flow velocity distribution on the entire cross section of the semi-inclined rectifying grid more uniform, ensure the uniformity of the flow field entering the catalyst inlet cross section, avoid the occurrence of high and low speed areas, and under the condition that the aspect ratio of the rectifying grid is the same, the present invention can further ensure that the deflection angle of the smoke incident catalyst streamline is much lower than that of the prior art, avoiding the problem of dust accumulation and wear of the catalyst due to excessive airflow incidence angle.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technology, and in particular to a smoke and air duct structure and a denitration system adapted to a semi-inclined rectifying grid. Background Art

[0002] At present, in order to ensure that the denitration catalyst of the ultra-low emission unit of the coal-fired power plant has a good denitration effect, higher requirements are put forward for the uniformity of the flow field and the streamline incident angle of the catalyst inlet section. Above the catalyst of the denitration device is a regular incident catalyst flue gas flow line, and a rectifier grid is arranged above the catalyst. There are many sites that use a semi-inclined rectifier grid structure. This semi-inclined rectifier grid structure will cause the angle of the flue gas incident on the catalyst to be skewed. At the same time, there will be obvious high and low speed areas near the front of the furnace and the end of the inclined section rectifier grid, resulting in uneven flow velocity distribution in the catalyst inlet section, affecting the denitration effect, and causing dust accumulation, blockage and wear on the catalyst surface.

[0003] In summary, the problems of the prior art are as follows:

[0004] 1. Due to the effect of the semi-inclined rectifier grid structure, there will be obvious high and low speed areas at the furnace front position and the end of the inclined rectifier grid, and the catalyst inlet velocity distribution deviation is large, such as Figure 2 As shown, it affects the denitrification effect. At the same time, the actual performance on site is the accumulation of dust, blockage and wear on the catalyst surface.

[0005] 2. The semi-inclined rectifier grid is arranged above the catalyst, which does not match the flue structure layout, directly resulting in the flue gas incident on the catalyst at a too large angle, such as Figure 3 As shown, the catalyst wear and dust accumulation problems are further aggravated. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a smoke and air duct structure and a denitrification system adapted to a semi-inclined rectifying grid. The present invention can ensure the uniformity of the velocity before entering the first layer of catalyst after passing through the semi-inclined rectifying grid, while helping to reduce the deflection angle of the airflow incident on the catalyst.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A smoke and air duct structure adapted for a semi-inclined rectifying grid comprises a smoke and air duct body, wherein the smoke and air duct body comprises a smoke and air duct inlet, a smoke and air duct outlet and a top cover inclined smoke duct which are interconnected, wherein the smoke and air duct inlet and the smoke and air duct outlet are connected through the top cover inclined smoke duct, wherein a semi-inclined rectifying grid is arranged on the top of the smoke and air duct outlet, wherein an inclined rectifying grid of the semi-inclined rectifying grid is located on a side close to the smoke and air duct inlet, and a catalyst is arranged on the top of the smoke and air duct outlet below the semi-inclined rectifying grid;

[0009] A first guide component and a second guide component are provided at the end of the smoke and air duct entrance. The first guide component is used to evenly guide the smoke in the low-level section of the smoke and air duct inlet into the semi-inclined section rectifying grid; the second guide component is used to evenly guide the smoke in the high-level section of the smoke and air duct inlet into the horizontal section rectifying grid of the semi-inclined rectifying grid.

[0010] Preferably, the first guide assembly includes a plurality of first guide plates, which are arranged at intervals along the height direction of the low-level flue, and the first guide plates include a low-level guide section guide plate and a low-level down-pressure section guide plate, which are connected to the low-level guide section guide plate, the low-level guide section guide plate is parallel to the flue gas flow direction at the entrance of the smoke and air duct, and the low-level down-pressure section guide plate is parallel to the top cover inclined flue;

[0011] The second guide assembly includes a plurality of second guide plates, which are arranged at intervals along the height direction of the low-level flue. The second guide plates include a high-level guide section guide plate and a high-level downward pressure section guide plate. The high-level guide section guide plate and the high-level downward pressure section guide plate are connected. The high-level guide section guide plate is parallel to the smoke flow direction at the entrance of the smoke and air duct, and the high-level downward pressure section guide plate is parallel to the inclined flue of the top cover.

[0012] Preferably, the height a of the low-level flue is calculated by the following formula:

[0013] a=b×c / d

[0014] Among them, b is the height of the high-level flue, c is the length of the inclined section rectifier grille, d is the length of the horizontal section rectifier grille, and the sum of the height a of the low-level flue and the height b of the high-level flue is the height of the smoke and air duct entrance.

[0015] Preferably, in the first guide assembly, the inflection point of all the first guide plates is located on the line between the central point and the bottom end point of the smoke and air duct inlet end, wherein the inflection point of the first guide plate is the connecting part of the low-position guide section guide plate and the low-position downward pressure section guide plate of the first guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue, passing through the top intersection point of the inclined section rectifier grille and the horizontal section rectifier grille, and the interface between the low-section flue and the high-section flue.

[0016] Preferably, the guide plates of the low-position guide sections of all the first guide plates are arranged at equal intervals, the lengths of all the guide plates of the low-position guide sections are the same, and the lengths of all the guide plates of the low-position downward pressure sections are the same.

[0017] Preferably, a distance is left between the guide plate of the low-position guide section of the lowest first guide plate among all the first guide plates and the bottom of the smoke and air duct inlet.

[0018] Preferably, in the second guide assembly, the inflection point of all the second guide plates is located on the line between the central point and the top end point of the smoke and air duct inlet end, wherein the inflection point of the second guide plate is the connecting part of the high-position guide section guide plate and the high-position downward pressure section guide plate of the second guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue, passing through the top intersection point of the inclined section rectifier grille and the horizontal section rectifier grille, and the interface between the low-section flue and the high-section flue.

[0019] Preferably, the guide plates of the high-position guide sections of all the second guide plates are arranged at equal intervals, the lengths of all the guide plates of the high-position guide sections are the same, and the lengths of all the guide plates of the high-position downward pressure sections are the same.

[0020] Preferably, the high-position downward pressure section guide plate of the lowest second guide plate among all the second guide plates is located on a straight line parallel to the top cover inclined flue and passing through the top intersection point of the inclined section rectifying grid and the horizontal section rectifying grid.

[0021] The present invention further provides a denitration system, the smoke and air duct structure of the denitration system adopts the smoke and air duct structure adapted to the semi-inclined rectifying grid as described above in the present invention.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] In the smoke and air duct structure adapted to the semi-inclined rectifying grid of the present invention, a first guide component and a second guide component are provided according to the characteristics of the semi-inclined rectifying grid. The first guide component can be used to evenly guide the smoke in the low-level smoke duct at the entrance of the smoke and air duct into the semi-inclined rectifying grid, and the second guide component can be used to evenly guide the smoke in the high-level smoke duct at the entrance of the smoke and air duct into the horizontal section rectifying grid of the semi-inclined rectifying grid. In this way, the smoke volume and flow velocity distribution on the entire cross-section of the semi-inclined rectifying grid can be more even, thereby ensuring the uniformity of the flow field in the cross-section entering the catalyst entrance, avoiding the occurrence of obvious high-speed and low-speed areas above the first layer of catalyst. When the width-to-height ratio of the rectifying grid is the same, the present invention can further ensure that the deflection angle of the smoke incident catalyst streamline is much lower than that of the prior art, thereby avoiding the problem of dust accumulation and wear of the catalyst due to excessive airflow incidence angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the smoke and air duct structure of the prior art;

[0025] Figure 2 It is a flow velocity distribution diagram of the catalyst inlet of the smoke and air duct structure of the prior art;

[0026] Figure 3 It is an air flow streamline diagram of the smoke and air duct structure of the prior art;

[0027] Figure 4It is a structural schematic diagram of the smoke and air duct structure adapted to the semi-inclined rectifying grid of the present invention;

[0028] Figure 5 This is a flow velocity distribution diagram of the catalyst inlet of the smoke and air duct structure adapted to the semi-inclined rectifying grid of the present invention;

[0029] Figure 6 It is an air flow streamline diagram of the smoke and air duct structure adapted to the semi-inclined rectifying grid of the present invention.

[0030] Among them: 1-smoke and air duct inlet, 2-low-position drainage section guide plate, 3-low-position downward pressure section guide plate, 4-high-position drainage section guide plate, 5-high-position downward pressure section guide plate, 6-top cover inclined flue, 7-inclined section rectifying grille, 8-horizontal section rectifying grille, 9-smoke and air duct outlet, 10-catalyst. DETAILED DESCRIPTION

[0031] The following are the drawings and specific embodiments of the present invention to further illustrate the present invention. 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.

[0032] Reference Figure 4 The present invention is adapted to a smoke and air duct structure of a semi-inclined rectifying grid, comprising a smoke and air duct body, wherein the smoke and air duct body comprises a smoke and air duct inlet 1, a smoke and air duct outlet 9 and a top cover inclined flue 6 which are interconnected, the smoke and air duct inlet 1 and the smoke and air duct outlet 9 are connected through the top cover inclined flue 6, a semi-inclined rectifying grid is provided on the top of the smoke and air duct outlet 9, an inclined section rectifying grid 7 of the semi-inclined rectifying grid is located on a side close to the smoke and air duct inlet 1, and a catalyst 10 is provided on the top of the smoke and air duct outlet 9 below the semi-inclined section rectifying grid; a first guide component and a second guide component are provided at the end of the smoke and air duct inlet 1, the first guide component is used to uniformly guide the smoke in the low-level section of the smoke and air duct inlet 1 into the inclined section rectifying grid 7; the second guide component is used to uniformly guide the smoke in the high-level section of the smoke and air duct inlet 1 into the horizontal section rectifying grid 8 of the semi-inclined rectifying grid. Comparison Figure 1 The present invention is to set a first guide component and a second guide component in the existing smoke and air duct structure, through which the flow field in the gas flow process can be fully evenly distributed to avoid the occurrence of local high and low speed areas, which is conducive to the uniform distribution of smoke when it flows through the semi-inclined rectifying grid and the angle of smoke incident on the catalyst is close to vertical. Figure 2 and Figure 5 By comparison, it can be seen that Figure 2 The velocity distribution of the catalyst inlet is extremely uneven near the entrance of the smoke and air duct, and the velocity distribution shows obvious peaks and troughs; Figure 5It can be seen that in the present invention, the catalyst inlet velocity is basically evenly distributed in the parts corresponding to the inclined section rectifying grid 7 and the horizontal section rectifying grid 8, and there is no part with large velocity fluctuation. The catalyst inlet velocity distribution deviation is significantly reduced as a whole compared with the existing structure deviation. Figure 3 and Figure 6 By comparison, it can be seen that Figure 3 After the flue gas passes through the semi-inclined rectifier grid, the flue gas above the catalyst (not entering the catalyst 10) tilts to the left, and the tilt becomes more and more serious from right to left; Figure 4 It can be seen that in the present invention, after the flue gas passes through the semi-inclined rectifier grid, the flue gas on the upper part of the first layer of catalyst (not entering the catalyst 10) is evenly distributed from right to left as a whole, and the streamline distribution is regular, eliminating the problem of the inclination of the streamline of the airflow incident catalyst.

[0033] As a preferred embodiment of the present invention, refer to Figure 4 The first guide assembly includes a plurality of first guide plates, which are arranged at intervals along the height direction of the low-level flue, and the first guide plates include a low-level guide section guide plate 2 and a low-level downward pressure section guide plate 3, the low-level guide section guide plate 2 and the low-level downward pressure section guide plate 3 are connected, the low-level guide section guide plate 2 is parallel to the smoke flow direction of the smoke and air duct inlet 1, and the low-level downward pressure section guide plate 3 is parallel to the top cover inclined flue 6; the second guide assembly includes a plurality of second guide plates, which are arranged at intervals along the height direction of the low-level flue, and the second guide plates include a high-level guide section guide plate 4 and a high-level downward pressure section guide plate 5, the high-level guide section guide plate 4 and the high-level downward pressure section guide plate 5 are connected, the high-level guide section guide plate 4 is parallel to the smoke flow direction of the smoke and air duct inlet 1, and the high-level downward pressure section guide plate 5 is parallel to the top cover inclined flue 6. Generally speaking, the first guide plate and the second guide plate have the same structure, both of which are folded plate structures. Due to the limitations of their respective installation spaces, they differ in size.

[0034] As a preferred embodiment of the present invention, refer to Figure 4 , the height a of the low-level flue is calculated by the following formula:

[0035] a=b×c / d

[0036] Among them, b is the height of the high-level flue, c is the length c of the inclined-level rectifying grid 7, d is the length of the horizontal-level rectifying grid 8, and the sum of the height a of the low-level flue and the height b of the high-level flue is the height of the smoke and air duct inlet 1.

[0037] As a preferred embodiment of the present invention, refer to Figure 4In the first guide assembly, the inflection points of all the first guide plates are located on the line between the central point and the bottom end point of the smoke and air duct inlet 1, wherein the inflection point of the first guide plate is the connection part of the low-position guide section guide plate 2 and the low-position downward pressure section guide plate 3 of the first guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue 6, passing through the top intersection point of the inclined section rectifying grille 7 and the horizontal section rectifying grille 8, and the interface between the low-section flue and the high-section flue.

[0038] As a preferred embodiment of the present invention, refer to Figure 4 The low-position guide section guide plates 2 of all first guide plates are arranged at equal intervals, the lengths of all low-position guide section guide plates 2 are the same, and the lengths of all low-position downward pressure section guide plates 3 are the same.

[0039] As a preferred embodiment of the present invention, refer to Figure 4 There is a gap between the low-position guide section guide plate 2 of the lowest first guide plate among all the first guide plates and the bottom of the smoke and air duct inlet 1. Firstly, the design of this structure takes advantage of the fact that the smoke can still flow normally under the lowest first guide plate to ensure the speed of the smoke flowing there, and prevent the accumulation of dust when passing the left end of the inclined section rectifying grid 7. At the same time, this gap is the same as the gap between the low-position guide section guide plates 2 and the low-position guide section guide plates 2.

[0040] As a preferred embodiment of the present invention, refer to Figure 4 In the second guide assembly, the inflection points of all the second guide plates are located on the line between the central point and the top end point of the smoke and air duct inlet 1, wherein the inflection point of the second guide plate is the connection part of the high-position guide section guide plate 4 and the high-position downward pressure section guide plate 5 of the second guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue 6, passing through the top intersection point of the inclined section rectifying grille 7 and the horizontal section rectifying grille 8, and the interface between the low-section flue and the high-section flue.

[0041] As a preferred embodiment of the present invention, refer to Figure 4 The high-position drainage section guide plates 4 of all second guide plates are arranged at equal intervals, the lengths of all high-position drainage section guide plates 4 are the same, and the lengths of all high-position downward pressure section guide plates 5 are the same.

[0042] As a preferred embodiment of the present invention, refer to Figure 4 The high-position downward pressure section guide plate 5 of the lowest second guide plate among all the second guide plates is located on a straight line parallel to the top cover inclined flue 6 and passing through the top intersection of the inclined section rectifying grid 7 and the horizontal section rectifying grid 8. The straight line is Figure 4As shown in the dotted line parallel to the inclined flue 6 of the top cover, the lowest second guide plate among the second guide plates is located exactly at the interface between the low-section flue and the high-section flue. The purpose of setting the high-position downward pressure section guide plate 5 here is that since the high-position downward pressure section guide plate 5 is longer than the low-position downward pressure section guide plate 3, the smoke can be smoothly separated here to keep the smoke flow field stable.

[0043] The present invention further provides a denitration system, the smoke and air duct structure of the denitration system adopts the smoke and air duct structure adapted to the semi-inclined rectifying grid as described above in the present invention.

[0044] Example

[0045] According to the actual on-site survey, the height dimension a+b of the smoke and air duct entrance 1, the length c of the inclined section rectifying grid, the length d of the horizontal section rectifying grid and the angle e of the top cover inclined smoke duct can be directly measured on-site; the height dimension a of the low-level smoke duct and the dimension a=b*c / d of the high-level smoke duct are determined, the height dimension of the low-level smoke duct is a, and the height dimension of the high-level smoke duct is b. This dimension calculation mode ensures that the smoke of the low-level smoke duct passes through the low-level drainage section guide plate 2 and the low-level down-pressure section guide plate 3, and then all enters the inclined section rectifying grid 7, and the smoke of the high-level smoke duct passes through the high-level drainage section guide plate 4 and the high-level down-pressure section guide plate 5, and then all enters the horizontal section rectifying grid 8, ensuring that the smoke and air duct outlet can continue the uniformity of the smoke volume and flow velocity of the smoke and air duct entrance, and ensuring the uniformity of the flow field of the catalyst inlet section;

[0046] The top intersection of the inclined section rectifier grid 7 and the horizontal section rectifier grid 8 is made into an auxiliary line along the angle e of the top cover inclined flue 6, and an intersection is generated with the interface of the low section flue and the high section flue. The intersection is used as the central point (such as Figure 4 As shown, the points where the corners of the high-position drainage section guide plate 4 and the high-position downward pressure section guide plate 5 of the lowest second guide plate are located coincide with the central point), and form an auxiliary line with the top end point of the smoke and air duct inlet 1, and all the internal guide plate intersections of the high-position drainage section guide plate 4 and the high-position downward pressure section guide plate 5 (i.e., the inflection points at the connection between the high-position drainage section guide plate 4 and the high-position downward pressure section guide plate 5) are on this auxiliary line, and all the second guide plates are evenly arranged along the auxiliary line; the central point then forms an auxiliary line with the bottom end point of the smoke and air duct inlet 1, and all the internal guide plate intersections of the low-position drainage section guide plate 2 and the low-position downward pressure section guide plate 3 (i.e., the inflection points at the connection between the low-position drainage section guide plate 2 and the low-position downward pressure section guide plate 3) are on this auxiliary line, and all the first guide plates are evenly arranged along the auxiliary line.

[0047] The guide plates 2 of the low-level drainage section are equidistantly distributed on the cross-section of the low-level section inlet flue to ensure that the airflow flow rates entering each channel of the low-level drainage section guide plates 2 are the same, and the number is determined according to the numerical simulation results; the guide plates 4 of the high-level drainage section are equidistantly distributed on the cross-section of the high-level section inlet flue to ensure that the airflow flow rates entering each channel of the high-level drainage section guide plates 4 are the same, and the number is determined according to the numerical simulation results.

[0048] The angles of the low-level down-pressure section guide plate 3 and the high-level down-pressure section guide plate 5 are consistent with the angle e of the top cover inclined flue, and their lengths are determined according to the numerical simulation results. The flow paths of the low-level down-pressure section guide plate 3 and the high-level down-pressure section guide plate 5 are similar, and the turning angles are the same, so the resistance coefficients are basically the same, and the flow rates of the various guide plate channels are basically the same, further ensuring the uniformity of the flow field at the catalyst inlet section. When the aspect ratio of the rectifier grid is sufficient, it also ensures that the angle of the flue gas incident on the catalyst is not deflected.

[0049] In summary, it can be seen that the present invention can ensure that the flow paths of each guide plate are similar, the steering angle is the same, the resistance coefficient is basically the same, and the catalyst inlet section can continue the uniformity of the flue gas volume and flow velocity at the smoke and air duct inlet, ensuring the uniformity of the flow field entering the catalyst inlet section. When the aspect ratio of the rectifying grid is sufficient, the angle of the flue gas incident on the catalyst is guaranteed not to be deflected, effectively reducing the problem of catalyst dust accumulation and wear.

Claims

1. A smoke and air duct structure adapted to a semi-inclined rectifier grid, characterized in that: The smoke duct body comprises a smoke duct inlet (1), a smoke duct outlet (9) and a top cover inclined smoke duct (6) which are interconnected, the smoke duct inlet (1) and the smoke duct outlet (9) are connected via the top cover inclined smoke duct (6), a semi-inclined rectifying grid is provided on the top of the smoke duct outlet (9), an inclined rectifying grid (7) of the semi-inclined rectifying grid is located on a side close to the smoke duct inlet (1), and a catalyst (10) is provided on the top of the smoke duct outlet (9) below the semi-inclined rectifying grid; A first flow guide component and a second flow guide component are provided at the end of the smoke and air duct inlet (1); the first flow guide component is used to uniformly guide the smoke in the low-level smoke duct in the smoke and air duct inlet (1) into the semi-inclined section rectifying grid; the second flow guide component is used to uniformly guide the smoke in the high-level smoke duct in the smoke and air duct inlet (1) into the horizontal section rectifying grid (8) of the semi-inclined rectifying grid; The first flow guide assembly comprises a plurality of first flow guide plates, the plurality of first flow guide plates being arranged at intervals along the height direction of the low-level flue, the first flow guide plates comprising a low-level flow guide plate (2) and a low-level downward pressure section flow guide plate (3), the low-level flow guide plate (2) and the low-level downward pressure section flow guide plate (3) being connected, the low-level flow guide plate (2) being parallel to the flue gas flow direction of the smoke and air duct inlet (1), and the low-level downward pressure section flow guide plate (3) being parallel to the top cover inclined flue (6); The second flow guide assembly comprises a plurality of second flow guide plates, the plurality of second flow guide plates being arranged at intervals along the height direction of the low-level flue, the second flow guide plates comprising a high-level flow guide plate (4) and a high-level downward pressure section flow guide plate (5), the high-level flow guide plate (4) and the high-level downward pressure section flow guide plate (5) being connected, the high-level flow guide plate (4) being parallel to the flue gas flow direction of the smoke and air duct inlet (1), and the high-level downward pressure section flow guide plate (5) being parallel to the top cover inclined flue (6); The height a of the low-level flue is calculated by the following formula: a=b×c / d Wherein, b is the height of the high-level flue, c is the length c of the inclined-level rectifying grid (7), d is the length of the horizontal-level rectifying grid (8), and the sum of the height a of the low-level flue and the height b of the high-level flue is the height of the smoke and air duct inlet (1); In the first guide assembly, the inflection points of all the first guide plates are located on the line between the central point and the bottom end point of the smoke and air duct inlet (1), wherein the inflection point of the first guide plate is the connection part of the low-position guide section guide plate (2) and the low-position downward pressure section guide plate (3) of the first guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue (6), passing through the top intersection point of the inclined section rectifying grille (7) and the horizontal section rectifying grille (8), and the interface between the low section flue and the high section flue; In the second guide assembly, the inflection points of all the second guide plates are located on the line between the central point and the top end point of the smoke and air duct inlet (1), wherein the inflection point of the second guide plate is the connection part of the high-position guide section guide plate (4) and the high-position downward pressure section guide plate (5) of the second guide plate, and the central point is the intersection of a straight line parallel to the top cover inclined flue (6), passing through the top intersection point of the inclined section rectifying grille (7) and the horizontal section rectifying grille (8), and the interface between the low section flue and the high section flue.

2. A smoke and air duct structure adapted to a semi-inclined rectifier grid according to claim 1, characterized in that: The low-position guide section guide plates (2) of all the first guide plates are arranged at equal intervals, the low-position guide section guide plates (2) have the same length, and the low-position downward pressure section guide plates (3) have the same length.

3. The smoke and air duct structure adapted to the semi-inclined rectifier grid according to claim 2 is characterized in that: A gap is left between the low-position guide section guide plate (2) of the lowest first guide plate among all the first guide plates and the bottom of the smoke and air duct inlet (1).

4. The smoke and air duct structure adapted to the semi-inclined rectifier grid according to claim 1, characterized in that: The high-position guide section guide plates (4) of all the second guide plates are arranged at equal intervals, the high-position guide section guide plates (4) have the same length, and the high-position downward pressure section guide plates (5) have the same length.

5. The smoke and air duct structure adapted to the semi-inclined rectifying grid according to claim 1, characterized in that: The high-position downward pressure section guide plate (5) of the lowest second guide plate among all the second guide plates is located on a straight line parallel to the top cover inclined flue (6) and passing through the top intersection point of the inclined section rectifying grid (7) and the horizontal section rectifying grid (8).

6. A denitration system, characterized in that: The smoke and air duct structure of the denitration system adopts the smoke and air duct structure adapted to the semi-inclined rectifying grid as described in any one of claims 1 to 5.

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