Coal mill nozzle ring moving ring and coal mill
By designing a detachable coal mill nozzle ring moving ring to increase the air circulation area, the problems of increased voltage drop and increased power consumption caused by nozzle ring wear are solved, and better separation of coal powder and reduced power consumption are achieved.
Patent Information
- Application Number
- CN202421747028.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-22
- Publication Date
- 2025-05-30
- Estimated Expiration
- 2034-07-22
AI Technical Summary
The nozzle ring of the coal mill is prone to wear on the upper part due to high wind speed and material impact. The prior art is divided into upper and lower parts and connected, but increases resistance, resulting in an increase in voltage drop and an increase in power consumption.
A coal mill nozzle ring is designed, including a detachable first and second annular body, a connecting plate and a fan blade plate, which increases the air circulation area, reduces resistance and reduces pressure drop by forming a flow channel.
It realizes convenient replacement of nozzle rings, reduces voltage drop, reduces production power consumption, and better separation of coal powder.
Smart Images
Figure CN222918757U_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of coal mills, and in particular, to a movable ring of a nozzle ring of a coal mill and a coal mill. Background Art
[0002] When the coal mill is working, since the wind speed at the nozzle ring is relatively high and it is simultaneously subjected to the impact of materials and pebble coal, the upper part of the nozzle ring is easily worn. In the related art, the nozzle ring is divided into upper and lower parts and connected by a connecting component to achieve local replacement of the nozzle ring, which is convenient for operation and saves costs. However, after the connecting component is set, the resistance of the nozzle ring is increased, resulting in an increase in the pressure drop of the nozzle ring, thereby increasing the production power consumption. Summary of the Utility Model
[0003] The purpose of the present disclosure is to provide a movable ring of a nozzle ring of a coal mill and a coal mill. The movable ring of the nozzle ring of the coal mill can reduce the pressure drop, increase the flow area of the primary air passing through the movable ring of the nozzle ring of the coal mill, and better separate the pulverized coal.
[0004] To achieve the above object, the present disclosure provides a movable ring of a nozzle ring of a coal mill. The movable ring of the nozzle ring of the coal mill includes: a first movable ring, the first movable ring includes a first annular main body and a first connecting plate, the first annular main body is used to be fixed to a grinding table of the coal mill, and a first channel is formed between the first annular main body and the first connecting plate; a second movable ring, the second movable ring includes a second annular main body and a second connecting plate, the second annular main body is detachably connected to the first annular main body and is used to be fixed to the grinding table of the coal mill, the second connecting plate is detachably connected to the first connecting plate, a second channel is formed between the second annular main body and the second connecting plate, and the second channel is communicated with the first channel to form a flow channel; and a first fan blade plate and a second fan blade plate, the first connecting plate connects the first annular main body through the first fan blade plate, the second connecting plate connects the second annular main body through the second fan blade plate, the first fan blade plate and the second fan blade plate are respectively provided with a first through hole and a second through hole, and both the first through hole and the second through hole are communicated with the flow channel.
[0005] Optionally, the movable ring of the nozzle ring of the coal mill further includes a third fan blade plate, the third fan blade plate connects the first annular main body and the first connecting plate, and the third fan blade plate is provided with a third through hole communicated with the flow channel.
[0006] Optionally, the third fan blade plate is welded to connect the first annular main body and the first connecting plate.
[0007] Optionally, a first connecting ear is connected to the first connecting plate, a second connecting ear is connected to the second connecting plate, the first connecting ear and the second connecting ear are attached to each other and are tightly connected by a first fastener.
[0008] Optionally, the mating surface of the first connecting ear and the second connecting ear is flush with the mating surface of the first connecting plate and the second connecting plate.
[0009] Optionally, the first annular body includes a connected first body section and a lapping section, an obtuse angle is formed between the first body section and the lapping section, the lapping section is provided with a mounting hole, the second annular body includes a second body section and a bending section, the bending section includes a connected first section and a second section, an obtuse angle is formed between the first section and the second section, the second section is connected to the second body section, the first section is provided with a connecting hole, the connecting hole is coaxially arranged with the mounting hole, the first body section and the second body section are coaxially arranged, the lapping section laps on the first section and is connected to the grinding disc by a second fastener.
[0010] Optionally, the number of the first connecting plates is multiple, the multiple first connecting plates are arranged at intervals along the circumferential direction of the first annular body, and each first connecting plate is respectively connected to the first annular body through its corresponding first fan blade plate, and the first fan blade plate is welded to connect the first connecting plate and the first annular body.
[0011] Optionally, the number of the second connecting plates is multiple, the multiple second connecting plates are arranged at intervals along the circumferential direction of the second annular body, and each second connecting plate is respectively connected to the second annular body through its corresponding second fan blade plate, and the second fan blade plate is welded to connect the second connecting plate and the second annular body.
[0012] Optionally, the number of the first through holes is multiple, and the diameter of the first through holes is 2 mm to 4 mm, and / or, the number of the second through holes is multiple, and the diameter of the second through holes is 0.5 mm to 2 mm.
[0013] On the basis of the above solution, the present disclosure further provides a coal mill, including a middle frame body, a grinding disc and a static ring of the coal mill nozzle ring. The static ring of the coal mill nozzle ring is fixed to the middle frame body. The coal mill further includes the above-mentioned moving ring of the coal mill nozzle ring. The moving ring of the coal mill nozzle ring is detachably connected to the grinding disc, and the static ring of the coal mill nozzle ring surrounds the moving ring of the coal mill nozzle ring.
[0014] With the above technical solution, in the movable ring of the mill nozzle ring provided in the present disclosure, the second annular body is detachably connected to the first annular body and is used to be fixed to the grinding table of the mill. The second connecting plate is detachably connected to the first connecting plate. The first connecting plate is connected to the first annular body through the first fan blade plate, and the second connecting plate is connected to the second annular body through the second fan blade plate. Therefore, when wear occurs at the upper end of the movable ring of the mill nozzle ring, by releasing the connections between the first annular body, the second annular body and the grinding table, and the connection between the first connecting plate and the second connecting plate, the first movable ring can be replaced, which is convenient for operation. In addition, since a first channel is formed between the first annular body and the first connecting plate, a second channel is formed between the second annular body and the second connecting plate, the second channel communicates with the first channel to form a circulation channel, and the first through hole on the first fan blade plate and the second through hole on the second fan blade plate are both communicated with the circulation channel, the flow area of the primary air passing through the movable ring of the mill nozzle ring can be increased, the resistance of the movable ring of the mill nozzle ring is reduced, the pressure drop of the movable ring of the mill nozzle ring is decreased, the pulverized coal can be better separated, and the production power consumption is reduced at the same time.
[0015] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Brief Description of the Drawings
[0016] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:
[0017] Figure 1 is a schematic installation diagram of the movable ring of the mill nozzle ring and the grinding table provided by an embodiment of the present disclosure;
[0018] Figure 2 is a sectional view of the movable ring of the mill nozzle ring provided by an embodiment of the present disclosure;
[0019] Figure 3 is a schematic structural diagram of the movable ring of the mill nozzle ring provided by an embodiment of the present disclosure;
[0020] Figure 4 is another schematic structural diagram of the movable ring of the mill nozzle ring provided by an embodiment of the present disclosure;
[0021] Figure 5 is a schematic structural diagram of the first fan blade plate in the movable ring of the mill nozzle ring provided by an embodiment of the present disclosure;
[0022] Figure 6 is a schematic structural diagram of the second fan blade plate in the movable ring of the mill nozzle ring provided by an embodiment of the present disclosure.
[0023] Description of the Reference Numerals
[0024] 1 - Moving ring of coal mill nozzle ring; 10 - First channel; 11 - First moving ring; 110 - First annular body; 1101 - First main body section; 1102 - Lapping section; 1103 - Mounting hole; 111 - First connecting plate; 112 - First connecting ear; 12 - Second moving ring; 120 - Second annular body; 1201 - Bent section; 1202 - Second main body section; 1203 - First section; 1204 - Second section; 121 - Second connecting plate; 122 - Second connecting ear; 2 - Stationary ring of coal mill nozzle ring; 20 - Second channel; 3 - First fan blade plate; 31 - First through hole; 4 - Second fan blade plate; 41 - Second through hole; 5 - Grinding table; 6 - Third fan blade plate; 7 - First fastener; 8 - Second fastener. Detailed implementation manners
[0025] The following will describe in detail the detailed implementation manners of the present disclosure with reference to the accompanying drawings. It should be understood that the detailed implementation manners described herein are only for explaining and illustrating the present disclosure, and are not used to limit the present disclosure.
[0026] In the present disclosure, the terms "first", "second", etc. used in the present disclosure are used to distinguish one element from another element, and do not have sequentiality and importance. In the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings represent the same or similar elements. The above definitions are only for explaining and illustrating the present disclosure, and should not be construed as a limitation to the present disclosure.
[0027] According to an exemplary implementation manner of the present disclosure, as shown in Figures 1 to 6 a moving ring of a coal mill nozzle ring is provided. The moving ring 1 of the coal mill nozzle ring includes: a first moving ring 11, the first moving ring 11 includes a first annular body 110 and a first connecting plate 111, the first annular body 110 is used for being fixed to the grinding table 5 of the coal mill, and a first channel 10 is formed between the first annular body 110 and the first connecting plate 111; a second moving ring 12, the second moving ring 12 includes a second annular body 120 and a second connecting plate 121, the second annular body 120 is detachably connected to the first annular body 110 and is used for being fixed to the grinding table 5 of the coal mill, the second connecting plate 121 is detachably connected to the first connecting plate 111, a second channel 20 is formed between the second annular body 120 and the second connecting plate 121, and the second channel 20 communicates with the first channel 10 to form a flow channel; and a first fan blade plate 3 and a second fan blade plate 4, the first connecting plate 111 is connected to the first annular body 110 through the first fan blade plate 3, the second connecting plate 121 is connected to the second annular body 120 through the second fan blade plate 4, the first fan blade plate 3 and the second fan blade plate 4 are respectively provided with a first through hole 31 and a second through hole 41, and both the first through hole 31 and the second through hole 41 communicate with the flow channel.
[0028] Through the above technical solution, in the movable ring of the mill nozzle ring provided by the present disclosure, the second annular main body 120 is detachably connected to the first annular main body 110 and is used to be fixed to the grinding table 5 of the mill. The second connecting plate 121 is detachably connected to the first connecting plate 111. The first connecting plate 111 is connected to the first annular main body 110 through the first fan blade 3, and the second connecting plate 121 is connected to the second annular main body 120 through the second fan blade 4. When wear occurs at the upper end of the movable ring of the mill nozzle ring, by releasing the connection between the first annular main body 110, the second annular main body 120 and the grinding table 5 and the connection between the first connecting plate 111 and the second connecting plate 121, the first movable ring 11 can be replaced, and the operation is convenient. In addition, since a first channel 10 is formed between the first annular main body 110 and the first connecting plate 111, a second channel 20 is formed between the second annular main body 120 and the second connecting plate 121, the second channel 20 communicates with the first channel 10 to form a flow channel, and the first through hole 31 on the first fan blade 3 and the second through hole 41 on the second fan blade 4 are both communicated with the flow channel, the flow area of the primary air passing through the movable ring of the mill nozzle ring can be increased, the resistance of the movable ring of the mill nozzle ring is reduced, thereby reducing the pressure drop of the movable ring of the mill nozzle ring, enabling better separation of pulverized coal, and at the same time reducing the production power consumption.
[0029] According to an exemplary embodiment of the present disclosure, referring to Figure 1 as shown in, the movable ring of the mill nozzle ring may further include a third fan blade 6. The third fan blade 6 connects the first annular main body 110 and the first connecting plate 111, and the third fan blade 6 is provided with a third through hole communicating with the flow channel. By providing the third fan blade 6, the connection strength between the first annular main body 110 and the first connecting plate 111 is improved. By providing the third through hole on the third fan blade 6 and communicating the third through hole with the flow channel, the flow area of the primary air passing through can be increased, which is beneficial to better separation of pulverized coal.
[0030] To improve the connection stability, the third fan blade 6 may be welded to connect the first annular main body 110 and the first connecting plate 111. Here, to improve the overall connection stability, the third fan blade 6 may be provided at one end of the first annular main body 110 close to the second annular main body 120. At the same time, the second fan blade 4 may also be provided at one end of the second annular main body 120 close to the first annular main body 110, and the third fan blade 6 is made to fit with the second fan blade 4, so that the contact area between the first movable ring 11 and the second movable ring 12 is increased, thereby improving the connection stability between the first movable ring 11 and the second movable ring 12.
[0031] According to an exemplary embodiment of the present disclosure, referring to Figure 2As shown, the first connecting plate 111 is connected with a first connecting ear 112, and the second connecting plate 121 is connected with a second connecting ear 122. The first connecting ear 112 and the second connecting ear 122 are mutually attached and tightly connected through a first fastener 7. In the above technical solution, the first fastener 7 can be a bolt or a connecting key. When the first fastener 7 is a bolt, the bolt sequentially passes through the first connecting ear 112 and the second connecting ear 112 and then is threadedly connected with a nut, thereby realizing the connection between the first moving ring 11 and the second moving ring 12, which is convenient for disassembly and assembly and easy for local replacement.
[0032] According to an exemplary embodiment of the present disclosure, referring to Figure 2 and Figure 3 As shown, the mating surfaces of the first connecting ear 112 and the second connecting ear 122 can be flush with the mating surfaces of the first connecting plate 111 and the second connecting plate 121. By such a setting, when the first connecting ear 112 and the second connecting ear 122 are connected through the first fastener 7, the first connecting plate 111 and the second connecting plate 121 can be driven to approach each other, and the first connecting plate 111 and the second connecting plate 121 can be attached more tightly, improving the connection reliability. In addition, the overall aesthetics is also improved.
[0033] According to an exemplary embodiment of the present disclosure, referring to Figure 2 As shown, the first annular body 110 can include a connected first body section 1101 and a lapping section 1102. An obtuse angle is arranged between the first body section 1101 and the lapping section 1102. The lapping section 1102 is provided with a mounting hole 1103. The second annular body 120 can include a second body section 1202 and a bending section 1201. The bending section 1201 includes a connected first section 1203 and a second section 1204. An obtuse angle is arranged between the first section 1203 and the second section 1204. The second section 1204 is connected to the second body section 1202. The first section 1203 is provided with a connection hole, and the connection hole is coaxially arranged with the mounting hole 1103. The first body section 1101 and the second body section 1202 are coaxially arranged. The lapping section 1102 laps on the first section 1203 and is connected to the grinding disc 5 through a second fastener 8. Through the above setting, both the first annular body 110 and the second annular body 120 are connected to the grinding disc 5, and there is a larger contact area between the second annular body 120 and the first annular body 110, improving the connection reliability. Among them, the second fastener 8 can be a screw. By adopting the above connection method, when local replacement is needed, only the connections between the first annular body 110, the second annular body 120 and the grinding disc 5 and the connection between the first connecting plate 111 and the second connecting plate 121 need to be released, and the disassembly and assembly are convenient.
[0034] According to an exemplary embodiment of the present disclosure, referring to Figure 3 and Figure 4As shown in the figure, the number of the first connecting plates 111 is multiple. The multiple first connecting plates 111 are arranged at intervals along the circumferential direction of the first annular body 110. And each first connecting plate 111 is respectively connected to the first annular body 110 through its corresponding first fan blade 3. The first fan blade 3 is welded to connect the first connecting plate 111 and the first annular body 110. Through the above arrangement, a plurality of first channels 10 are formed on the outer periphery of the first annular body 110. The first fan blade 3 is welded to connect the first connecting plate 111 and the first annular body 110. Since the first fan blade 3 is provided with a first through hole 31 and the first through hole 31 communicates with the first channel 10, the flow area of the primary air passing through the first moving ring 11 can be increased.
[0035] According to an exemplary embodiment of the present disclosure, referring to Figure 3 and Figure 4 As shown in the figure, the number of the second connecting plates 121 is multiple. The multiple second connecting plates 121 are arranged at intervals along the circumferential direction of the second annular body 120. And each second connecting plate 121 is respectively connected to the second annular body 120 through its corresponding second fan blade 4. The second fan blade 4 is welded to connect the second connecting plate 121 and the second annular body 120. In this way, a plurality of second channels 20 are formed on the outer periphery of the second annular body 120. The second fan blade 4 is welded to connect the second fan blade 4. Since the second fan blade 4 is provided with a second through hole 41 and the second through hole 41 communicates with the second channel 20, the flow area of the primary air passing through the second moving ring 12 can be increased.
[0036] In the present disclosure, referring to Figure 3 As shown in the figure, the multiple first channels 10 and the multiple second channels 20 are correspondingly communicated to form a plurality of flow channels, which improves the flow area of the primary air passing through the moving ring of the mill nozzle ring, increases the air volume, and enables better separation of the pulverized coal. In addition, since only the first fan blade 3, the second fan blade 4 and the third fan blade 6 are provided in the flow channel, and the second fan blade 4 and the third fan blade 6 are in contact with each other, there are more gaps formed in the flow channel, so that the ungrindable pebble coal can pass more smoothly between two adjacent fan blades, reducing the risk of blockage, and at the same time avoiding the problem of reduced air volume caused by blockage, and improving the effect of the pulverized coal being blown upward.
[0037] According to an exemplary embodiment of the present disclosure, referring to Figure 5 and Figure 6As shown, the number of the first through holes 31 can be multiple, and the diameter of the first through holes 31 is 2 mm to 4 mm. Exemplarily, the diameter of the first through holes 31 can be 2 mm, 3 mm or 4 mm, which increases the flow area of the primary air and facilitates the separation of pulverized coal. The number of the second through holes 41 can also be multiple, and the diameter of the second through holes 41 is 0.5 mm to 2 mm. Exemplarily, the diameter of the second through holes 41 can be 0.5 mm, 1 mm or 2 mm. In this way, the diameter of the second through holes 41 not only meets the requirement of increasing the flow area of the primary air, but also ensures the strength of the second moving ring 12. Among them, the first through holes 31 and the second through holes 41 can be arranged in a staggered manner or in a matrix arrangement, and the present disclosure does not limit this.
[0038] On the basis of the above solution, the present disclosure further provides a coal mill, including a middle frame body, a grinding table 5 and a static ring 2 of the coal mill nozzle ring. The static ring 2 of the coal mill nozzle ring is fixed to the middle frame body. The coal mill further includes the above-mentioned moving ring of the coal mill nozzle ring. The moving ring 1 of the coal mill nozzle ring is detachably connected to the grinding table 5, and the static ring 2 of the coal mill nozzle ring surrounds the moving ring 1 of the coal mill nozzle ring. Here, the relevant content of the static ring 2 of the coal mill nozzle ring has been described in detail in the foregoing content. To avoid repetition, the present disclosure will not elaborate herein.
[0039] Combined Figures 1 to 6 When the moving ring of the coal mill nozzle ring is installed, each first connecting plate 111 is respectively connected to the second annular body 120 through its corresponding first fan blade 3 to form the first moving ring 11. Each first connecting plate 111 is connected to the second annular body 120 through its corresponding third fan blade 6. Each second connecting plate 121 is respectively connected to the second annular body 120 through its corresponding second fan blade 4 to form the second moving ring 12. Then, the first section 1203 of the second moving ring 12 is lapped on the grinding table 5, the lapping section 1102 of the first moving ring 11 is lapped on the first section 1203 so that the connecting hole and the mounting hole 1103 are coaxially arranged, and the first main body section 1101 and the second main body section 1202 are coaxially arranged. Then, the second fastener 8 is sequentially passed through the mounting hole 1103 and the connecting hole and then connected to the grinding table 5. Each first connecting ear 112 and the corresponding second connecting ear 122 are tightly connected by the first fastener 7. Thus, the installation of the moving ring of the coal mill nozzle ring is completed. When the moving ring of the coal mill nozzle ring is worn, the connection between the first moving ring 11, the second moving ring 12 and the grinding table 5 is released by removing the second fastener 8, and the connection between the first moving ring 11 and the second moving ring 12 is released by removing the first fastener 7. Then, the worn first moving ring 11 or second moving ring 12 is removed, and a new first moving ring 11 or second moving ring 12 is replaced according to the above installation method. The operation is convenient, and compared with replacing the whole moving ring of the coal mill nozzle ring, the cost is saved.
[0040] In the above solution, both the first moving ring 11 and the second moving ring 12 can be evenly divided into 2 - 6 segments along the circumferential direction. Exemplarily, they can be divided into 3 segments or 6 segments. In this way, when a large area of wear occurs on the first moving ring 11 or the second moving ring 12, it can be replaced segment by segment, improving the replacement efficiency.
[0041] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.
[0042] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.
[0043] Furthermore, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.
Claims
1. A coal mill nozzle ring, characterized in that: The coal mill nozzle ring includes: a first moving ring, the first moving ring comprising a first annular body and a first connecting plate, the first annular body being used to be fixed to a grinding disc of a coal mill, and a first channel being formed between the first annular body and the first connecting plate; a second movable ring, the second movable ring comprising a second annular body and a second connecting plate, the second annular body being detachably connected to the first annular body and used to be fixed to a grinding disc of the coal mill, the second connecting plate being detachably connected to the first connecting plate, a second channel being formed between the second annular body and the second connecting plate, the second channel being interconnected with the first channel to form a circulation channel; and A first blade plate and a second blade plate, the first connecting plate is connected to the first annular body through the first blade plate, the second connecting plate is connected to the second annular body through the second blade plate, the first blade plate and the second blade plate are respectively provided with a first through hole and a second through hole, and the first through hole and the second through hole are both connected to the circulation channel.
2. The coal mill nozzle ring according to claim 1, characterized in that: The coal mill nozzle annular ring further includes a third blade plate, the third blade plate connects the first annular body and the first connecting plate, and the third blade plate is provided with a third through hole connected to the circulation channel.
3. The coal mill nozzle ring according to claim 2, characterized in that: The third fan blade plate is welded to connect the first annular body and the first connecting plate.
4. The coal mill nozzle ring according to claim 1, characterized in that: The first connecting plate is connected with a first connecting ear, the second connecting plate is connected with a second connecting ear, the first connecting ear and the second connecting ear are fitted to each other and are fastened together by a first fastener.
5. The coal mill nozzle ring according to claim 4, characterized in that: The fitting surfaces of the first connecting ear and the second connecting ear are flush with the fitting surfaces of the first connecting plate and the second connecting plate.
6. The coal mill nozzle ring according to claim 1, characterized in that: The first annular body comprises a first main body section and an overlapping section connected to each other, the first main body section and the overlapping section are arranged at an obtuse angle, and the overlapping section is provided with a mounting hole. The second annular body includes a second main body section and a bent section, the bent section includes a first section and a second section connected to each other, the first section and the second section are arranged at an obtuse angle, the second section is connected to the second main body section, the first section is provided with a connecting hole, and the connecting hole is coaxially arranged with the mounting hole, The first main body section is coaxially arranged with the second main body section, and the overlapping section overlaps the first section and is connected to the grinding disc via a second fastener.
7. The coal mill nozzle ring according to claim 1, characterized in that: There are multiple first connecting plates, which are arranged at intervals along the circumference of the first annular body, and each of the first connecting plates is connected to the first annular body through its corresponding first blade plate, and the first blade plate is welded to connect the first connecting plate and the first annular body.
8. The coal mill nozzle ring according to claim 1, characterized in that: There are multiple second connecting plates, which are arranged at intervals along the circumference of the second annular body, and each of the second connecting plates is connected to the second annular body through its own corresponding second blade plate, and the second blade plate is welded to connect the second connecting plate and the second annular body.
9. The coal mill nozzle ring according to claim 1, characterized in that: The number of the first through holes is plural, and the diameter of the first through holes is 2 mm to 4 mm, and / or, The number of the second through holes is plural, and the diameter of the second through holes is 0.5 mm to 2 mm.
10. A coal mill, characterized in that: It includes a middle frame, a grinding disc and a coal mill nozzle ring static ring, the coal mill nozzle ring static ring is fixed to the middle frame, and is characterized in that the coal mill also includes a coal mill nozzle ring dynamic ring according to any one of claims 1-9, the coal mill nozzle ring dynamic ring is detachably connected to the grinding disc, and the coal mill nozzle ring static ring is arranged around the coal mill nozzle ring dynamic ring.