Coal mill air duct capable of preventing airflow scouring

Abstract

The invention belongs to the technical field of coal mill pulverizing equipment, and particularly relates to a coal mill air duct capable of preventing airflow scouring, the coal mill air duct comprises an air duct body and a flow blocking assembly, the air duct body comprises an upper rectangular air duct, an upper rectangular elbow, a vertical rectangular air duct, a lower rectangular elbow and a lower rectangular air duct which are communicated in sequence; the flow choking assembly comprises vertical flow choking rings arranged in the upper rectangular air channel and the lower rectangular air channel, and inclined flow choking rings and bent flow choking pieces arranged in the upper rectangular elbow and the lower rectangular elbow. Air flow stagnation areas are formed on the inner walls of the upper rectangular air duct and the lower rectangular air duct through the vertical flow choking rings, and dust-containing hot air is prevented from directly washing the inner wall of the air duct body; besides, the upper rectangular elbow and the lower rectangular elbow adopt the mode that inclined flow blocking rings and bent flow blocking pieces are matched with each other, a plurality of airflow stagnation areas which are in a grid shape on the whole are formed on the first wall face and the second wall face, and the effect that airflow can still be prevented from scouring the inner wall of the air duct body in a complex flow field is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mill pulverizing equipment, and particularly relates to a coal mill air duct that prevents air flow erosion. Background Art

[0002] When the hot air entering the coal mill flows through the rotary air preheater, it will inevitably mix with some dust. When this hot air containing dust flows in the air duct, the dust will often form a strong erosion on the wall surface of the air duct under the drive of the air flow. In severe cases, the wall surface of the air duct will even be worn through. Since the flow area of the coal mill air duct is significantly smaller than that of the hot air main pipe, when the hot air flow with dust passes through the coal mill air duct, the wind speed increases significantly, resulting in a very common erosion phenomenon on the inner wall of the coal mill air duct.

[0003] In response to the erosion phenomenon of the coal mill air duct, at present, it is mainly solved by measures such as pasting ceramics or coating mastic on the inner wall of the air duct. However, the ceramics have the problem of insecure pasting and are very easy to fall off. And the mastic has a relatively large mass, which increases a large load on the air duct, and the cost of the mastic is relatively high. Therefore, it is of great significance to design an air duct with low cost and good anti-air flow erosion effect. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a coal mill air duct that prevents air flow erosion. A flow-limiting component is provided on the inner wall of each part of the air duct body, and the cooperation of each component in the flow-limiting component forms an air flow stagnation area on the inner wall of the air duct body to prevent the air flow from eroding the inner wall of the air duct.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A coal mill air duct that prevents air flow erosion is arranged between the hot air main pipe and the coal mill body and is used to transfer the hot air provided by the hot air main pipe to the coal mill body. The coal mill air duct includes:

[0007] An air duct body, including a upper rectangular air duct, an upper rectangular elbow, a vertical rectangular air duct, a lower rectangular elbow, and a lower rectangular air duct that are connected in sequence. One port of the upper rectangular air duct is connected to the hot air main pipe, one port of the lower rectangular air duct is connected to the coal mill body, and after the hot air provided by the hot air main pipe enters the interior of the air duct body from the upper rectangular air duct, it sequentially passes through the upper rectangular elbow, the vertical rectangular air duct, the lower rectangular elbow, and the lower rectangular air duct, and finally is transferred to the coal mill body. In addition, the included angle between the two port directions of the upper rectangular elbow is 90°, and the included angle between the two port directions of the lower rectangular elbow is also 90°;

[0008] The flow blocking component includes a number of vertical flow blocking rings. A number of the vertical flow blocking rings are parallel to each other and evenly distributed at equal intervals on the inner walls of the upper rectangular air duct and the lower rectangular air duct, and the vertical flow blocking rings are perpendicular to the inner walls of the upper rectangular air duct and the lower rectangular air duct;

[0009] In addition, the flow blocking component further includes a number of inclined flow blocking rings and a number of bent flow blocking sheets arranged inside the upper rectangular elbow and the lower rectangular elbow, where:

[0010] The number of inclined flow blocking rings is configured into two groups, and each group of inclined flow blocking rings is evenly arranged inside the upper rectangular elbow and the lower rectangular elbow in such a form that the angle between any two adjacent inclined flow blocking rings is equal, based on the vertices of the bending angles of the upper rectangular elbow and the lower rectangular elbow as axes respectively; in addition, the inner wall surfaces of the upper rectangular elbow and the lower rectangular elbow away from the vertices of the bending angles are respectively configured as the first wall surface and the second wall surface, and a number of bent flow blocking sheets are evenly arranged on the first wall surface and the second wall surface of the upper rectangular elbow and the lower rectangular elbow respectively at equal intervals on the basis that the extending direction coincides with the flowing direction of the hot air;

[0011] The body structure of the upper rectangular elbow is configured as a first air inlet part and a first air outlet part according to the sequential flowing path of the hot air. Among them, among the number of inclined flow blocking rings located inside the upper rectangular elbow, a part of the inclined flow blocking rings configured inside the first air outlet part are at 90° at the position fixed to the first wall surface; in addition, the body structure of the lower rectangular elbow is configured as a second air inlet part and a second air outlet part according to the sequential flowing path of the hot air. Among them, among the number of inclined flow blocking rings located inside the lower rectangular elbow, a part of the inclined flow blocking rings configured inside the second air outlet part are also at 90° at the position fixed to the second wall surface;

[0012] On this basis, according to the flowing direction of the hot air inside the upper rectangular elbow and the lower rectangular elbow, the angle of the windward direction among the angles formed by a number of inclined flow blocking rings with the first wall surface and the second wall surface respectively is the windward angle β, and β ≤ 90°.

[0013] Preferably, in the flow blocking component, both the vertical flow blocking rings and the inclined flow blocking rings are formed by enclosing four rectangular flow blocking unit plates, and the four flow blocking unit plates are welded and fixed to each other. In addition, the vertical flow blocking rings, the inclined flow blocking rings, and the bent flow blocking sheets are also welded and fixed to the inner wall of the air duct body.

[0014] Preferably, in the vertical flow blocking rings and the inclined flow blocking rings, the length of the flow blocking unit plate matches the inner wall of the air duct body. The width of the flow blocking unit plate is L1, and 20 mm < L1 < 50 mm. The thickness of the flow blocking unit plate is L2, and 4 mm < L2 < 10 mm.

[0015] Preferably, in the upper rectangular elbow and the lower rectangular elbow, the included angle between two adjacent inclined flow blocking rings is α, and 20° < α < 40°.

[0016] Preferably, in the upper rectangular elbow and the lower rectangular elbow, the width of the bent flow blocking piece is L3, and 20 mm < L3 < 50 mm, and the thickness of the bent flow blocking piece is L4, and 4 mm < L4 < 10 mm.

[0017] Preferably, in the upper rectangular elbow and the lower rectangular elbow, the distance between two adjacent bent flow blocking pieces is L5, and 200 mm < L5 < 400 mm.

[0018] Preferably, in the upper rectangular air duct and the lower rectangular air duct, the distance between two adjacent vertical flow blocking rings is L6, and 200 mm < L6 < 400 mm.

[0019] Preferably, in the upper rectangular air duct and the lower rectangular air duct, an air flow stagnation zone is formed between two adjacent vertical flow blocking rings.

[0020] Preferably, in the upper rectangular elbow and the lower rectangular elbow, the flow blocking unit plates fixed and welded to the first wall surface and the second wall surface in each inclined flow blocking ring are formed plates, and several of the formed plates intersect with several of the bent flow blocking pieces to form several grid-shaped air flow stagnation zones.

[0021] Preferably, in the flow blocking assembly, the vertical flow blocking rings, the inclined flow blocking rings and the bent flow blocking pieces are all made of carbon steel.

[0022] The beneficial effects of the present invention are as follows:

[0023] Generally speaking, the present invention arranges several vertical flow blocking rings on the inner walls of the upper rectangular air duct and the lower rectangular air duct, and utilizes the properties of fluid mechanics. When the hot air flows to the vertical flow blocking rings, under the blocking action of the vertical flow blocking rings, the air flow cannot continue to flow along the inner wall surface of the air duct body. Therefore, the kinetic energy of the air flow is converted into potential energy, that is, the flow velocity decreases and the pressure increases. Therefore, an air flow stagnation zone is formed in the area between two adjacent vertical flow blocking rings. Due to the high-pressure characteristics brought by the conversion of kinetic energy to potential energy in this air flow stagnation zone, the air pressure outside the air flow stagnation zone is lower than the pressure inside the air flow stagnation zone. Therefore, the air flow outside the air flow stagnation zone cannot enter the air flow stagnation zone, and thus the dust carried by the air flow will not enter the stagnation zone, so that the air duct wall surface will not be scoured.

[0024] In addition, since the flow field of the hot air flow at the upper rectangular elbow and the lower rectangular elbow is more complex and the turbulence is stronger, on the basis of the mutual cooperation of the inclined baffle ring and the bent baffle at the upper rectangular elbow and the lower rectangular elbow, a number of overall grid-shaped air flow stagnation areas are formed on both the first wall surface and the second wall surface, achieving the effect of preventing the air flow from scouring the inner wall of the air duct under a complex flow field; in addition, the present invention also limits the size of the windward angle β formed by the inclined baffle ring and the first wall surface and the second wall surface to β ≤ 90°, such a setting is beneficial to the formation of the air flow stagnation area at this position, enabling the device to generally achieve the effect of preventing air flow scouring on the premise of cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 Front view schematic diagram of the overall structure of the present invention;

[0027] Figure 2 Front view partial structure schematic diagram of the upper rectangular elbow of the present invention;

[0028] Figure 3 Three-dimensional structure schematic diagram of the upper rectangular elbow of the present invention;

[0029] Figure 4 Front view partial structure schematic diagram of the lower rectangular elbow of the present invention;

[0030] Figure 5 Three-dimensional structure schematic diagram of the lower rectangular elbow of the present invention;

[0031] Figure 6 Combined structure schematic diagram of the baffle unit plate of the present invention;

[0032] Figure 7 Schematic diagram of the formation method of the air flow stagnation area of the present invention;

[0033] Figure 8 Side view partial structure schematic diagram of the upper rectangular elbow of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention; the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] Next, the solution provided by the present invention will be described in detail in conjunction with the accompanying drawings.

[0037] In the present technical solution, as Figure 1 shown, a pulverizer air duct for preventing air flow erosion is provided between the hot air main pipe 1 and the pulverizer body 2, and is used to transfer the hot air provided by the hot air main pipe 1 into the pulverizer body 2. Among them, the pulverizer air duct includes: an air duct body 3 and a flow blocking component 4.

[0038] Specifically, the air duct body 3 includes a rectangular upper air duct 301, a rectangular upper elbow 302, a vertical rectangular air duct 303, a rectangular lower elbow 304, and a rectangular lower air duct 305 that are connected in sequence. The cross-sections of the rectangular upper air duct 301, the rectangular upper elbow 302, the vertical rectangular air duct 303, the rectangular lower elbow 304, and the rectangular lower air duct 305 are all rectangular. One port of the rectangular upper air duct 301 is connected to the hot air main pipe 1, and one port of the rectangular lower air duct 305 is connected to the mill body 2. After the hot air provided by the hot air main pipe 1 enters the air duct body through the rectangular upper air duct 301, it passes through the rectangular upper elbow 302, the vertical rectangular air duct 303, the rectangular lower elbow 304, and the rectangular lower air duct 305 in sequence, and finally is transmitted to the mill body 2. In addition, the included angle between the two port directions of the rectangular upper elbow 302 is 90°, and the included angle between the two port directions of the rectangular lower elbow 304 is also 90°. The specific structure is as Figure 1 shown.

[0039] As the core of this application, a flow blocking component 4 is arranged inside the air duct body 3 to achieve the effect of preventing the inner wall of the air duct body 3 from being scoured by the air flow. Specifically, as Figure 1 shown, the flow blocking component 4 includes a plurality of vertical flow blocking rings 5. The plurality of vertical flow blocking rings 5 are parallel to each other and evenly distributed at equal intervals on the inner walls of the rectangular upper air duct 301 and the rectangular lower air duct 305, and the vertical flow blocking rings 5 are perpendicular to the inner walls of the rectangular upper air duct 301 and the rectangular lower air duct 305.

[0040] In addition, as Figures 1-5 shown, the flow blocking component 4 further includes a plurality of inclined flow blocking rings 6 and a plurality of curved flow blocking sheets 7 arranged inside the rectangular upper elbow 302 and the rectangular lower elbow 304, where:

[0041] The plurality of inclined flow blocking rings 6 are configured into two groups. Each group of inclined flow blocking rings 6 is evenly arranged inside the rectangular upper elbow 302 and the rectangular lower elbow 304 in the form that the included angle α between any two adjacent inclined flow blocking rings 6 is 20° < α < 40° on the basis of taking the vertex O of the bending angle of the rectangular upper elbow 302 and the rectangular lower elbow 304 as the axis. The specific structure is as Figures 2-5 shown; in addition, the inner wall surfaces of the rectangular upper elbow 302 and the rectangular lower elbow 304 far from the vertex O of the bending angle are respectively configured as the first wall surface 306 and the second wall surface 307, and the plurality of curved flow blocking sheets 7 are evenly arranged on the first wall surface 306 and the second wall surface 307 of the rectangular upper elbow 302 and the rectangular lower elbow 304 at equal intervals on the basis that the extending direction coincides with the flowing direction of the hot air.

[0042] More specifically, in the flow blocking component 4, as Figure 6As shown in the figure, the vertical flow blocking ring 5 and the inclined flow blocking ring 6 are both formed by enclosing four rectangular flow blocking unit plates 8, and the four flow blocking unit plates 8 are welded and fixed to each other. In addition, the vertical flow blocking ring 5, the inclined flow blocking ring 6, and the bent flow blocking piece 7 are also welded and fixed to the inner wall of the air duct body 3. Among them:

[0043] In the vertical flow blocking ring 5 and the inclined flow blocking ring 6, the length of the flow blocking unit plate 8 is matched with the inner wall of the air duct body 3. The width of the flow blocking unit plate 8 is L1, and 20mm < L1 < 50mm. The thickness of the flow blocking unit plate 8 is L2, and 4mm < L2 < 10mm. The specific structure is as Figures 6-7 shown.

[0044] In the upper rectangular elbow 302 and the lower rectangular elbow 304, the width of the bent flow blocking piece 7 is L3, and 20mm < L3 < 50mm. The thickness of the bent flow blocking piece 7 is L4, and 4mm < L4 < 10mm. The specific structure is as Figure 8 shown.

[0045] In the upper rectangular elbow 302 and the lower rectangular elbow 304, the distance between two adjacent bent flow blocking pieces 7 is L5, and 200mm < L5 < 400mm; in the upper rectangular air duct 301 and the lower rectangular air duct 305, the distance between two adjacent vertical flow blocking rings 5 is L6, and 200mm < L6 < 400mm. The specific structure is as Figure 1 、 Figure 8 shown.

[0046] Based on the above core points, the limitation of the included angle α between two adjacent inclined flow blocking rings 6, the limitation of the width L1 and thickness L2 of the flow blocking unit plate 8, and the limitation of the width L3 and thickness L4 of the bent flow blocking piece 7 are set in cooperation based on the properties of fluid mechanics in the prior art. That is, on the basis of fluid mechanics, the pulverizer air duct is designed according to the value ranges of the above various quantities, and the anti-airflow erosion effect obtained is more significant, and the service life of the air duct is extended.

[0047] Specifically: Based on the above structure, in the upper rectangular air duct 301 and the lower rectangular air duct 305, an air flow stagnation area 9 is formed between two adjacent vertical flow blocking rings 5; the formation of the air flow stagnation area 9 is due to: when the hot air flow reaches the vertical flow blocking ring 5, under the blocking effect of the vertical flow blocking ring 5, the hot air flow cannot continue to flow along the inner wall surface of the air duct body 3, so the kinetic energy of the hot air flow is converted into potential energy, that is, the flow rate decreases and the pressure increases. Therefore, an air flow stagnation area 9 is formed in the area between two adjacent vertical flow blocking rings 5, and an air film protection wind is formed in the air flow stagnation area 9; and due to the high-pressure characteristic brought by the conversion of kinetic energy to potential energy in the air flow stagnation area 9, the pressure of the hot air flow outside the air flow stagnation area 9 is lower than the pressure inside the air flow stagnation area 9. Therefore, the hot air flow outside the air flow stagnation area 9 cannot enter the air flow stagnation area 9, so the dust carried by the hot air flow will not enter the air flow stagnation area 9 either, and thus will not cause erosion to the air duct wall surface; on this basis, the air film protection wind refers to the air in the air flow stagnation area 9, and the air film protection wind isolates the inner wall surface of the air duct body 3 and the hot air flow inside the air duct body 3, and can prevent the hot air flow inside the air duct body 3 from entraining dust to abrade the inner wall surface.

[0048] As another core of the present invention, the present application also conducts a structural design at the upper rectangular elbow 302 and the lower rectangular elbow 304 where the hot air flow field environment is more complex for the generation of the air flow stagnation area 9, specifically as Figure 3 、 Figure 5 shown. In the upper rectangular elbow 302 and the lower rectangular elbow 304, the flow blocking unit plates 8 that are fixedly welded to the first wall surface 306 and the second wall surface 307 in each inclined flow blocking ring 6 are configured as forming plates, and a plurality of forming plates intersect with a plurality of bent flow blocking pieces 7 to form a plurality of air flow stagnation areas 9 that are generally in a grid shape.

[0049] In addition, the present application also conducts an adaptive design on the specific structure of some inclined flow blocking rings 6 according to the formation method of the air flow stagnation area 9 in fluid mechanics, as Figure 7 shown. According to the flow direction of the hot air inside the upper rectangular elbow 302 and the lower rectangular elbow 304, the included angle in the windward direction among the included angles formed by a plurality of inclined flow blocking rings 6 and the first wall surface 306 and the second wall surface 307 respectively is the windward angle β, β ≤ 90°; and in order to specifically adapt to the setting of the windward angle β, the present application configures the body structure of the upper rectangular elbow 302 as a first air inlet part 10 and a first air outlet part 11 according to the sequential flow path of the hot air. Among them, among the plurality of inclined flow blocking rings 6 located inside the upper rectangular elbow 302, the part of the inclined flow blocking rings 6 arranged inside the first air outlet part 11 is at 90° at the position fixed to the first wall surface 306, that is, the forming plate of the part of the inclined flow blocking rings 6 located inside the first air outlet part 11 is perpendicular to the first wall surface 306. The specific structure is as Figures 2-5As shown in the figure; in addition, in the present application, the body structure of the lower rectangular elbow 304 is configured as a second air inlet part 12 and a second air outlet part 13 according to the sequential flow path of the hot air. Among them, among the several inclined flow blocking rings 6 located inside the lower rectangular elbow 304, the part of the inclined flow blocking rings 6 configured inside the second air outlet part 13 is also at 90° at the position fixed to the second wall surface 307, that is, the forming plate of the part of the inclined flow blocking rings 6 located inside the second air outlet part 13 is perpendicular to the second wall surface 307.

[0050] Based on the above structure, such a setting facilitates the formation of the air flow stagnation zone 9. Because from the perspective of fluid mechanics, if the windward angles β formed by the inclined flow blocking rings 6 and the first wall surface 306 and the second wall surface 307 are greater than 90°, when the hot air flow passes through the inclined flow blocking rings 6, a component velocity in the radial direction of the air duct body 3 will be generated. Even if this velocity is very low, it will cause the hot air flow to flow along the surface of the inclined flow blocking rings 6, so that the appearance of the air flow stagnation zone 9 cannot be ensured, thus destroying the air film protection wind near the inner wall surface of the air duct body 3. Therefore, in the present application, through the improvement of the structure of the inclined flow blocking rings 6, the situation where the windward angles β formed by the inclined flow blocking rings 6 and the first wall surface 306 and the second wall surface 307 are greater than 90° is prevented, and the smooth generation of the air flow stagnation zone 9 is achieved, and finally a good anti-scouring effect is obtained.

[0051] In the present technical solution, in the flow blocking assembly 4, the vertical flow blocking ring 5, the inclined flow blocking ring 6, and the bent flow blocking piece 7 are all made of carbon steel, and their high hardness and high corrosion resistance are used to provide a structural basis for the formation of the air flow stagnation zone 9.

[0052] Generally speaking, based on the actual working conditions that the hot air sequentially flows through the upper rectangular air duct 301, the upper rectangular elbow 302, the vertical rectangular air duct 303, the lower rectangular elbow 304, the lower rectangular air duct 305 and finally is transmitted to the coal mill body 2, several vertical flow blocking rings 5 are arranged inside the upper rectangular air duct 301 and the lower rectangular air duct 305, and based on the properties of fluid mechanics, an air flow stagnation zone 9 is formed between any two adjacent vertical flow blocking rings 5 to prevent the hot air flow from scouring the inner walls of the upper rectangular air duct 301 and the lower rectangular air duct 305.

[0053] In addition, in the present application, several inclined flow blocking rings 6 and several bent flow blocking pieces 7 are designed to intersect with each other, and several air flow stagnation zones 9 that are generally in a grid shape are formed at the upper rectangular elbow 302 and the lower rectangular elbow 304 where the hot air flow field environment is more complex, and the inner wall of the air duct body 3 is further protected by the air flow stagnation zone 9.

[0054] On this basis, in order to facilitate the formation of the airflow stagnation zone 9 at the upper rectangular elbow 302 and the lower rectangular elbow 304, the present application also limits the magnitude of the windward angle β formed by the inclined baffle ring 6 and the first wall surface 306 and the second wall surface 307 to not more than 90°. And in order to adapt to this limiting condition, the present application also makes an adaptive design of the specific structure of some of the inclined baffle rings 6 to prevent the situation where the windward angle β formed by the inclined baffle ring 6 and the first wall surface 306 and the second wall surface 307 is greater than 90°, so as to ensure the smooth generation of the airflow stagnation zone 9 and finally achieve a good anti-erosion effect.

[0055] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A pulverizer air duct resistant to air flow scouring is arranged between the hot air main pipe and the pulverizer body and is used to transfer the hot air provided by the hot air main pipe into the pulverizer body. It is characterized in that, The coal mill air duct includes: An air duct body, including a upper rectangular air duct, an upper rectangular elbow, a vertical rectangular air duct, a lower rectangular elbow, and a lower rectangular air duct that are connected in sequence. One port of the upper rectangular air duct is connected to the hot air main pipe, and one port of the lower rectangular air duct is connected to the coal mill body. After the hot air provided by the hot air main pipe enters the interior of the air duct body from the upper rectangular air duct, it passes through the upper rectangular elbow, the vertical rectangular air duct, the lower rectangular elbow, and the lower rectangular air duct in sequence, and finally is transmitted to the coal mill body. In addition, the included angle between the two port directions of the upper rectangular elbow is 90°, and the included angle between the two port directions of the lower rectangular elbow is also 90°; A flow blocking component, including a plurality of vertical flow blocking rings. The plurality of vertical flow blocking rings are parallel to each other and evenly distributed at equal intervals on the inner walls of the upper rectangular air duct and the lower rectangular air duct, and the vertical flow blocking rings are perpendicular to the inner walls of the upper rectangular air duct and the lower rectangular air duct; In addition, the flow blocking component further includes a plurality of inclined flow blocking rings and a plurality of bent flow blocking sheets arranged inside the upper rectangular elbow and the lower rectangular elbow, where: The plurality of inclined flow blocking rings are configured into two groups, and each group of inclined flow blocking rings is evenly arranged inside the upper rectangular elbow and the lower rectangular elbow in a form where the included angle between any two adjacent inclined flow blocking rings is equal, based on the vertices of the bending angles of the upper rectangular elbow and the lower rectangular elbow as axes respectively. In addition, the inner wall surfaces of the upper rectangular elbow and the lower rectangular elbow away from the vertices of the bending angles are respectively configured as the first wall surface and the second wall surface, and the plurality of bent flow blocking sheets are evenly arranged on the first wall surface and the second wall surface of the upper rectangular elbow and the lower rectangular elbow at equal intervals based on the extension direction coinciding with the flow direction of the hot air; The body structure of the upper rectangular elbow is configured as a first air inlet part and a first air outlet part according to the sequential flow path of the hot air. Among the plurality of inclined flow blocking rings located inside the upper rectangular elbow, some of the inclined flow blocking rings configured inside the first air outlet part are at 90° at positions fixed to the first wall surface. In addition, the body structure of the lower rectangular elbow is configured as a second air inlet part and a second air outlet part according to the sequential flow path of the hot air. Among the plurality of inclined flow blocking rings located inside the lower rectangular elbow, some of the inclined flow blocking rings configured inside the second air outlet part are also at 90° at positions fixed to the second wall surface; On this basis, according to the flow direction of the hot air inside the upper rectangular elbow and the lower rectangular elbow, the included angle between the plurality of inclined flow blocking rings and the first wall surface and the second wall surface in the windward direction is the windward angle β, and β ≤ 90°.

2. The air duct of the coal mill for preventing air flow erosion according to claim 1, characterized in that: In the flow blocking component, the vertical flow blocking rings and the inclined flow blocking rings are each formed by enclosing four rectangular flow blocking unit plates, and the four flow blocking unit plates are welded and fixed to each other. In addition, the vertical flow blocking rings, the inclined flow blocking rings, and the bent flow blocking sheets are also welded and fixed to the inner wall of the air duct body.

3. The air duct of the coal mill for preventing air flow scouring according to claim 2, characterized in that: In the vertical flow-blocking ring and the inclined flow-blocking ring, the length of the flow-blocking unit plate matches the inner wall of the air duct body. The width of the flow-blocking unit plate is L1, and 20 mm < L1 < 50 mm. The thickness of the flow-blocking unit plate is L2, and 4 mm < L2 < 10 mm.

4. A pulverizer air duct for preventing air flow scouring according to claim 3, characterized in that: In the upper rectangular elbow and the lower rectangular elbow, the included angle between two adjacent inclined flow-blocking rings is α, and 20° < α < 40°.

5. A pulverizer air duct for preventing air flow erosion according to claim 4, characterized in that: In the upper rectangular elbow and the lower rectangular elbow, the width of the bent flow-blocking piece is L3, and 20 mm < L3 < 50 mm. The thickness of the bent flow-blocking piece is L4, and 4 mm < L4 < 10 mm.

6. The air duct of the coal mill for preventing air flow scouring according to claim 5, wherein: In the upper rectangular elbow and the lower rectangular elbow, the distance between two adjacent bent flow-blocking pieces is L5, and 200 mm < L5 < 400 mm.

7. The air duct of the coal mill for preventing air flow scouring according to claim 6, characterized in that: In the upper rectangular air duct and the lower rectangular air duct, the distance between two adjacent vertical flow-blocking rings is L6, and 200 mm < L6 < 400 mm.

8. A pulverizer air duct for preventing air flow scouring according to claim 7, characterized in that: In the upper rectangular air duct and the lower rectangular air duct, an air flow stagnation zone is formed between two adjacent vertical flow-blocking rings.

9. The pulverizer air duct for preventing air flow scouring according to claim 8, characterized in that: In the upper rectangular elbow and the lower rectangular elbow, the flow-blocking unit plates fixedly welded to the first wall surface and the second wall surface in each inclined flow-blocking ring are formed plates. A plurality of the formed plates and a plurality of the bent flow-blocking pieces intersect with each other to form a plurality of air flow stagnation zones that are generally in a grid shape.

10. A pulverizer air duct for preventing air flow erosion according to claim 9, characterized in that: In the flow-blocking assembly, the vertical flow-blocking ring, the inclined flow-blocking ring, and the bent flow-blocking piece are all made of carbon steel.

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