Coal mill movable and stationary ring structure

Abstract

The application relates to the technical field of coal chemical grinding equipment, in particular to a movable and static ring structure of a coal mill, which comprises a movable ring main body, a static ring and a grinding disc, the static ring is arranged on the inner wall of the coal mill, and the movable ring main body is coaxially arranged with the static ring; the movable ring main body comprises an inner ring wall and an outer ring wall, the inner ring wall is fixedly connected with the outer ring wall; the inner ring wall is detachably connected with the edge of the grinding disc; the inner ring wall and the outer ring wall jointly enclose an air channel for circulating primary air, the air channel is sequentially divided into multiple stepped sections along the direction of air flow from the inlet to the outlet, and the air flow circulation cross-sectional area in each stepped section remains constant; a sudden change step is arranged between the two adjacent stepped sections, and the step surface of the sudden change step faces the downstream direction of the air flow. The application has the effect of significantly improving the primary air outlet velocity and the turbulence intensity and enhancing the carrying and separating capacity of the coal powder particles by designing the air channel as the stepped section structure with the air flow direction stepwise decreasing in the air flow direction.

Description

Technical Field

[0001] This application relates to the technical field of coal chemical pulverizing equipment, and in particular to a coal mill motor stationary ring structure. Background Technology

[0002] Medium-speed coal mills are core equipment in coal powder preparation systems of thermal power plants and coal chemical enterprises. During the operation of the coal mill, the moving ring (also known as the air ring or nozzle ring) serves as the channel for hot primary air to enter the grinding zone inside the coal mill. Its air duct profile directly determines the outlet velocity field of the primary air, the powder delivery capacity, and the overall ventilation resistance of the machine.

[0003] Currently, the conventional circulating air duct for coal mills in the industry mainly involves setting up air inlets next to the mill disc, and then ventilating from the bottom of the coal mill to blow coal powder from the mill disc to the upper outlet for collection. However, the air inlets at the edge of the mill disc are relatively large and the air velocity is low. The primary air in the air duct is basically in a laminar or weakly turbulent state. The lateral distribution of coal powder particles in the airflow is uneven, resulting in high coal powder concentration and low air velocity in some areas. As a result, the efficiency of blowing coal powder upward is low and the collection rate is slow.

[0004] Therefore, the low intensity of upward airflow inside the coal mill results in a weak ability to carry and separate pulverized coal, which is the problem that needs to be solved. Summary of the Invention

[0005] To solve the above problems, this application provides a coal mill moving stationary ring structure, which adopts the following technical solution: Includes the rotating ring body, the stationary ring, and the grinding disc; The stationary ring is disposed on the inner wall of the coal mill; The moving ring body is coaxially arranged with the stationary ring; the moving ring body includes an inner ring wall and an outer ring wall, the inner ring wall and the outer ring wall are fixedly connected; the inner ring wall is detachably connected to the edge of the grinding disc; the inner ring wall and the outer ring wall together form an air passage for the flow of primary air; The air passage is divided into multiple stepped sections along the direction of airflow from the inlet to the outlet, and the airflow cross-sectional area within each stepped section remains constant; a sudden step is provided between two adjacent stepped sections, and the step surface of the sudden step faces the downstream direction of the airflow, so that the airflow cross-sectional area of ​​the air passage decreases in a stepped manner along the direction of airflow.

[0006] By adopting the above technical solution, the cross-sectional area of ​​the air passage decreases in a stepwise manner along the airflow direction. According to the fluid continuity equation, the airflow velocity increases accordingly when the cross-sectional area decreases, thereby obtaining a higher primary air velocity at the air passage outlet. At the same time, the cross-sectional area remains constant within each step, allowing the airflow to develop stably within that step. However, local vortex disturbances are generated at abrupt steps, causing the airflow to change from a laminar or weakly turbulent state to a strongly turbulent state. This enhances the lateral mixing and carrying capacity of the airflow for pulverized coal particles, effectively improves the uniformity of pulverized coal concentration distribution in the airflow, and increases the efficiency and collection rate of upward-blown pulverized coal.

[0007] Optionally, the airway is divided into 3 to 5 stepped sections along the airflow direction; The ratio of the flow cross-sectional area at the inlet to the flow cross-sectional area at the outlet of the airway is 1.5 to 3.0.

[0008] By adopting the above technical solution, the number of stepped sections is limited to 3 to 5, which ensures that there are enough steps to accelerate the airflow step by step and subject it to multiple step disturbances to achieve full turbulence, while avoiding the situation where too many steps result in too small a step height, making the disturbance effect insignificant or increasing the processing difficulty. The ratio of the inlet to outlet cross-sectional area is 1.5 to 3.0, ensuring that the airflow obtains a velocity gain of 1.5 to 3.0 times at the outlet. This significantly improves the outlet wind speed and powder delivery capacity while keeping the total ventilation resistance within a reasonable range, avoiding excessive pressure loss caused by a sudden reduction in cross-sectional area.

[0009] Optionally, the abrupt step is disposed on the inner ring wall and / or the outer ring wall; The step height of the abrupt change step is 5% to 15% of the radial width of the airway at the step location.

[0010] By adopting the above technical solution, the abrupt step can be flexibly set on the inner ring wall, outer ring wall, or both, which facilitates adaptive design according to the actual airway configuration and installation space. The step height is limited to 5% to 15% of the radial width of the airway. Steps within this range can generate sufficiently strong backward step vortices to enhance the turbulent mixing effect, without causing severe flow separation and excessive local pressure loss due to excessive step height, thus achieving an optimal balance between turbulence acceleration and resistance control.

[0011] Optionally, along the airflow direction, the length of each of the stepped segments accounts for 15% to 25% of the total length of the airway; The length of the step segment closest to the airway outlet is shorter than the length of the step segment closest to the airway inlet.

[0012] By adopting the above technical solution, the length of each step segment accounts for 15% to 25% of the total length, ensuring that the airflow has sufficient flow development distance in each step segment. This allows the airflow to reattach and stabilize after passing through the abrupt step disturbance, avoiding the situation where the vortex generated by the previous step enters the next step before it dissipates, resulting in flow turbulence and superimposed energy loss. The length of the step segment at the outlet end is shorter than that at the inlet end because the airflow velocity is already high and the Reynolds number is large near the outlet, and the distance required for flow reattachment is relatively short. Shortening the length of the outlet end segment allows for a reasonable allocation of the proportion of each segment within the limited total length of the air passage, while maintaining a high turbulence intensity before the outlet, which is beneficial for the uniform dispersion and efficient carrying of pulverized coal.

[0013] Optionally, the abrupt step has a plurality of flow-guiding ribs on its surface; the plurality of flow-guiding ribs are arranged at intervals along the radial direction of the abrupt step, and the height of the flow-guiding ribs is 30% to 50% of the step height.

[0014] By adopting the above technical solution, the guide ribs are set on the step surface and arranged at radial intervals, which can break the large-scale backflow vortex formed at the step into multiple small-scale vortices, accelerate the dissipation of vortices and the reattachment process of airflow, reduce the range of low-pressure backflow zone behind the step, and thus reduce local pressure loss. The height of the guide ribs is 30% to 50% of the step height, which can effectively guide the airflow direction and suppress large-scale separation, without forming new obstacles due to excessive rib height. At the same time, the guide ribs can also enhance the uniformity of airflow in the radial direction, making the coal powder particles more evenly distributed on the cross-section of the air passage.

[0015] Optionally, the airway wall within the stepped section is provided with drag-reducing microstructures; the drag-reducing microstructures include multiple micro-ridge-like protrusions arranged parallel to the airflow direction.

[0016] By adopting the above technical solution, the drag-reducing microstructure formed by the micro-ridge protrusions can suppress the development of transverse vortices in the near-wall region, reduce wall friction resistance, and reduce energy loss caused by wall friction in each step of the airflow. In the stepped acceleration air passage, the airflow velocity increases step by step along the path, and the wall friction resistance increases accordingly. The drag-reducing microstructure can effectively compensate for the additional friction loss caused by acceleration, so that more airflow energy can be used to improve the outlet wind speed and coal powder carrying capacity, rather than being consumed by wall friction.

[0017] Optionally, the ridge height of the micro-ridge protrusion is 0.1 mm to 0.5 mm, and the ridge distance between two adjacent micro-ridge protrusions is 0.5 mm to 2 mm.

[0018] By adopting the above technical solution, the size range of ridge height from 0.1 mm to 0.5 mm and ridge spacing from 0.5 mm to 2 mm matches the typical flow Reynolds number and near-wall turbulent boundary layer thickness in the coal mill motor annular gas passage. This effectively embeds the ridge-shaped protrusions into the viscous sublayer region, limiting the spanwise scale of the transverse turbulent vortex, thereby achieving a significant drag reduction effect. This size range also takes into account both processing feasibility and wear resistance, avoiding rapid wear failure under high-concentration coal powder airflow due to excessively small ridge height, or excessively large ridge height that increases roughness drag.

[0019] Optionally, the moving ring body is divided into 12 to 16 moving ring segments along the circumference. Adjacent moving ring segments can be disassembled and spliced ​​to form a complete circular ring structure, and each moving ring segment is interchangeable.

[0020] By adopting the above technical solution, the main body of the rotating ring is divided into 12 to 16 equal segments. Each segment has a moderate size and weight, making it easy to enter and exit through the coal mill maintenance port, thus solving the problem of difficult overall hoisting of large-diameter rotating rings. The segments are interchangeable, meaning that any segment can be replaced individually after wear without disassembling the entire rotating ring, significantly shortening maintenance downtime and reducing spare parts management costs. At the same time, the number of segments is in the range of 12 to 16, which ensures that there are enough segments to control the weight of a single segment, while avoiding excessively dense splicing seams due to too many segments, which would affect the continuity and sealing of the inner wall of the gas passage.

[0021] Optionally, it also includes multiple air passage blades, the grinding disc is provided with a groove, and the multiple air passage blades are circumferentially spaced in the groove; the moving ring body and the air passage blades are integrally formed using high-chromium wear-resistant alloy material.

[0022] By adopting the above technical solutions, high-chromium wear-resistant alloy materials have excellent wear resistance and high-temperature oxidation resistance, which can effectively resist the continuous erosion and wear of high-concentration coal powder gas flow and extend the service life of the dynamic ring. The one-piece molding process eliminates the welding joint between the dynamic ring body and the gas duct blade, avoiding the problem of preferential wear and cracking caused by uneven material and residual stress at the weld. At the same time, it ensures the smooth continuity of the gas duct inner wall, which is conducive to maintaining the accuracy of the designed stepped gas duct profile and the integrity of the drag-reducing microstructure.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. The cross-sectional area of ​​the air passage decreases in a stepwise manner along the airflow direction. According to the fluid continuity equation, the airflow velocity increases accordingly when the cross-sectional area decreases, thus obtaining a higher primary air velocity at the air passage outlet. At the same time, the cross-sectional area remains constant within each step, allowing the airflow to develop stably within that step. However, local vortex disturbances are generated at abrupt steps, causing the airflow to change from a laminar or weakly turbulent state to a strongly turbulent state. This enhances the airflow's ability to laterally mix and carry coal powder particles, effectively improving the uniformity of coal powder concentration distribution in the airflow and increasing the efficiency and collection rate of upward-blown coal powder. 2. By setting guide ribs on the abrupt step surface, the large-scale backflow vortex is broken into small-scale vortices, which accelerates the reattachment of airflow, reduces local pressure loss, and improves the uniformity of airflow in the radial direction, making the coal powder concentration distribution more uniform. 3. By setting micro-ridge-shaped protrusions on the airway wall in the stepped section to reduce drag, the wall friction resistance is effectively reduced, the additional friction energy loss caused by the gradual acceleration of airflow is reduced, and more kinetic energy is used to improve the outlet wind speed and pulverized coal carrying efficiency. 4. By dividing the main body of the rotating ring into 12 to 16 interchangeable detachable sections and using high-chromium wear-resistant alloy for one-piece molding, the convenience of installation and maintenance, the interchangeability of spare parts, and the overall wear resistance life are taken into account, thereby reducing operation and maintenance costs. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the coal mill moving ring structure according to an embodiment of this application; Figure 2 This is a cross-sectional schematic diagram of the coal mill moving ring structure according to an embodiment of this application; Figure 3 This is a schematic longitudinal cross-sectional view of the airway along the airflow direction in an embodiment of this application; Figure 4 yes Figure 3 An enlarged schematic diagram of part A in the middle; Figure 5 yes Figure 3 Enlarged schematic diagram of part B; In the picture, 1. Main body of the moving ring; 11. Inner ring wall; 12. Outer ring wall; 13. Moving ring segment; 2. Static ring; 3. Airway; 31. Stepped section; 32. Abrupt step; 321. Step surface; 322. Guide rib; 4. Grinding disc; 5. Air passage blades; 6. Drag-reducing microstructure. Detailed Implementation

[0025] The following is in conjunction with the appendix Figure 1 - Appendix Figure 5 This application will be described in further detail below.

[0026] A coal mill motor stationary ring structure, with reference to Figure 1-3 The mill includes a rotating ring body 1, a stationary ring 2, and a grinding disc 4. The stationary ring 2 is located on the inner wall of the coal mill. The rotating ring body 1 is circular in shape and coaxially arranged with the stationary ring 2. The rotating ring body 1 includes an inner ring wall 11 and an outer ring wall 12. The inner ring wall 11 is located radially inside the outer ring wall 12, and the inner ring wall 11 and the outer ring wall 12 are fixedly connected. The inner ring wall 11 and the outer ring wall 12 together form an air passage 3 for the flow of primary air. The air passage 3 is divided into multiple stepped sections 31 along the direction of airflow from the inlet to the outlet. The cross-sectional area of ​​airflow in each stepped section 31 remains constant. A sudden step 32 is provided between two adjacent stepped sections 31, and the step surface 321 of the sudden step 32 faces the downstream direction of the airflow.

[0027] Reference Figure 1 The main body 1 of the rotating ring is divided into multiple rotating ring segments 13 along its circumference. The central angle of each rotating ring segment 13 is approximately 25.7°. Adjacent rotating ring segments 13 are connected detachably by flange face fitting and high-strength bolts, thus forming a complete ring structure. The external dimensions, mounting hole positions, and air passage 3 profiles of each rotating ring segment 13 are completely identical, and they are interchangeable, meaning that any rotating ring segment 13 can be installed at any position on the ring. When a rotating ring segment 13 needs to be replaced due to wear, only the connecting bolts corresponding to that segment need to be removed, the worn segment can be taken out, and a new segment can be inserted; it is not necessary to remove the entire rotating ring. In other embodiments, the number of rotating ring segments 13 can also be adaptively selected according to the diameter of the coal mill and the size of the inspection port.

[0028] Reference Figure 1 and Figure 2 The grinding disc 4 has a groove, and multiple air passage blades 5 are evenly spaced within the groove along the circumference of the moving ring body 1. The moving ring body 1 and the air passage blades 5 are integrally formed from a high-chromium wear-resistant alloy material. The mass fraction of chromium in the high-chromium wear-resistant alloy material is not less than 25%, which has excellent resistance to coal powder erosion and wear and high-temperature oxidation resistance. Primary air enters from the inlet of the air passage 3 (located below the moving ring), is accelerated by the air passage 3, and is blown out from the outlet of the air passage 3 (located above the moving ring), carrying the ground coal powder on the grinding disc 4 upwards to the separator.

[0029] Reference Figure 3The air passage 3 is divided into multiple stepped sections 31 along the direction of airflow from the inlet to the outlet. In this embodiment, the air passage 3 is divided into four stepped sections 31 along the airflow direction, which are numbered sequentially as the first stepped section 31, the second stepped section 31, the third stepped section 31, and the fourth stepped section 31. The airflow cross-sectional area within each stepped section 31 remains constant, that is, within the same stepped section 31, the area of ​​the flow cross-section enclosed by the inner annular wall 11, the outer annular wall 12, and the air passage blades 5 on both sides does not change along the airflow direction.

[0030] Reference Figure 3 Abrupt step 32 is provided between two adjacent stepped sections 31. The step surface 321 of the abrupt step 32 faces the downstream direction of the airflow, that is, the step surface 321 is approximately perpendicular to the airflow direction. As a result, the flow cross-sectional area of ​​the air passage 3 decreases in a stepped manner along the airflow direction: every time the airflow passes through an abrupt step 32, the flow cross-sectional area suddenly shrinks by one level, and then remains unchanged in the next stepped section 31 until it reaches the next abrupt step 32 and shrinks again.

[0031] In this embodiment, the ratio of the flow cross-sectional area at the inlet to the flow cross-sectional area at the outlet of the air duct 3 is 2.0. That is, as the airflow travels from the inlet to the outlet, the total flow cross-sectional area is reduced to half of its original size. According to the continuity equation, the average airflow velocity at the outlet is approximately twice that at the inlet. In other embodiments, this ratio can be adjusted within the range of 1.5 to 3.0 depending on the model and operating conditions of the coal mill. When the ratio is 1.5, the acceleration effect is relatively mild, suitable for applications with strict ventilation resistance requirements; when the ratio is 3.0, the acceleration effect is significant, suitable for large coal mills requiring higher outlet air velocities to enhance pulverized coal carrying capacity.

[0032] The step height of the abrupt change step 32 is 10% of the radial width of the air passage 3 at that step location. For example, if the radial width of the air passage 3 at the abrupt change step 32 between the first step segment 31 and the second step segment 31 is 50 mm, then the step height of the abrupt change step 32 (i.e., the sum of the step height on the inner ring wall 11 side and the step height on the outer ring wall 12 side) is 5 mm. In other embodiments, the step height can be adjusted within the range of 5% to 15% of the radial width of the air passage 3. When the step height is 5%, the step disturbance is weaker and the pressure loss is smaller; when the step height is 15%, the step disturbance is stronger and the turbulent mixing effect is more significant.

[0033] Along the airflow direction, the length of the first step segment 31 accounts for 25% of the total length of the airway 3, the second step segment 31 accounts for 22%, the third step segment 31 accounts for 18%, and the fourth step segment 31 accounts for 15%. That is, the length of the fourth step segment 31, closest to the outlet of the airway 3, is shorter than the length of the first step segment 31, closest to the inlet of the airway 3. The remaining 20% ​​of the total length of the airway 3 is allocated to the transition area occupied by the three abrupt transition steps 32. This arrangement, where the length of each step segment 31 decreases along the airflow direction, allows the airflow to have a longer stable development distance at the inlet, while at the outlet, due to the already high airflow velocity and Reynolds number, the distance required for reattachment is shorter, thus the length of the step segments 31 is correspondingly shortened. This achieves a reasonable allocation of the proportions of each segment within the limited total length of the airway 3.

[0034] Furthermore, refer to Figure 3 and Figure 4 The abrupt step 32 has a plurality of guide ribs 322 on its step surface 321. These guide ribs 322 are spaced apart along the radial direction of the abrupt step 32 (i.e., from the inner annular wall 11 to the outer annular wall 12). In this embodiment, each abrupt step 32 has 3 to 5 guide ribs 322 on its step surface 321, and the height of the guide ribs 322 is 40% of the step height. For example, if the step height is 5 mm, the height of the guide ribs 322 is 2 mm. The cross-section of the guide ribs 322 is triangular, with the apex pointing downstream of the airflow and the base adhering to the step surface 321. The guide ribs 322 can break the large-scale backflow vortex formed behind the step into multiple small-scale vortices, accelerating the dissipation of the vortices and the reattachment process of the airflow, reducing the range of the backflow zone, and thus reducing local pressure loss. In other embodiments, the height of the guide rib 322 can be adjusted within the range of 30% to 50% of the step height, and the cross-sectional shape of the guide rib 322 can also be semi-circular or rectangular.

[0035] Furthermore, refer to Figure 5The airway 3 within the stepped section 31 has drag-reducing microstructures 6 on its wall surface. The drag-reducing microstructures 6 include multiple micro-ridge-like protrusions arranged parallel to the airflow direction. These micro-ridge-like protrusions are located on the inner surface of the inner ring wall 11, the inner surface of the outer ring wall 12, and the side surface of the airway blades 5. In this embodiment, the ridge height of the micro-ridge-like protrusions is 0.3 mm, and the ridge distance between two adjacent micro-ridge-like protrusions is 1 mm. The cross-section of the micro-ridge-like protrusions is triangular, with the ridge tips pointing towards the interior of the airway 3. In other embodiments, the ridge height of the micro-ridge-like protrusions can be selected from 0.1 mm to 0.5 mm, and the ridge distance can be selected from 0.5 mm to 2 mm, with the specific values ​​optimized based on the airflow velocity and Reynolds number within the airway 3. A combination of a ridge height of 0.1 mm and a ridge distance of 0.5 mm is suitable for the inlet section with lower airflow velocity; a combination of a ridge height of 0.5 mm and a ridge distance of 2 mm is suitable for the outlet section with higher airflow velocity. Micro-ridge-like protrusions are formed on the wall of airway 3 by precision casting or laser processing.

[0036] The implementation principle of this application embodiment is as follows: During coal mill operation, hot primary air enters the inlet of air duct 3 from below the moving ring, first entering the first step section. Within the first step section, the airflow develops fully in the constant cross-sectional area channel, and the flow tends to stabilize. When the airflow reaches the first abrupt step 32, the flow cross-sectional area suddenly shrinks, the airflow velocity increases sharply, and a backward step vortex is generated behind the step. The guide ribs 322 on the step surface 321 break the large vortex into smaller vortices, promoting rapid reattachment of the airflow. The airflow then enters the second step section, where it stabilizes again within the constant cross-sectional area. This gradual acceleration and disturbance occurs as the airflow passes through the second and third abrupt steps, with the flow cross-sectional area decreasing progressively, the airflow velocity increasing progressively, and the turbulence intensity increasing progressively. Finally, the airflow exits at high speed from the outlet of the fourth step section, carrying the coal powder particles on the mill disc upwards to the separator with high velocity and strong turbulence intensity.

[0037] Throughout the flow process, the drag-reducing microstructures 6 on the walls of each stepped section 31 continuously reduce wall friction resistance, allowing more airflow energy to be used to increase the outlet velocity rather than being consumed by wall friction. The main body 1 of the rotating ring is integrally molded from a high-chromium wear-resistant alloy, ensuring the accuracy of the airflow profile and its wear-resistant life. When individual rotating ring sections 13 become severely worn due to long-term operation, they can be replaced individually by removing bolts, making maintenance convenient and minimizing downtime.

[0038] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A coal mill moving stationary ring structure, characterized in that, It includes a moving ring body (1), a stationary ring (2), and a grinding disc (4); The stationary ring (2) is installed on the inner wall of the coal mill; The moving ring body (1) is coaxially arranged with the stationary ring (2); the moving ring body (1) includes an inner ring wall (11) and an outer ring wall (12), the inner ring wall (11) and the outer ring wall (12) are fixedly connected; the inner ring wall (11) is detachably connected to the edge of the grinding disc (4); the inner ring wall (11) and the outer ring wall (12) together form an air passage (3) for the flow of primary air. The air passage (3) is divided into multiple stepped sections (31) along the direction of airflow from inlet to outlet. The cross-sectional area of ​​airflow in each stepped section (31) remains constant. A sudden step (32) is provided between two adjacent stepped sections (31). The step surface (321) of the sudden step (32) faces the downstream direction of the airflow, so that the cross-sectional area of ​​the air passage (3) decreases in a stepped manner along the direction of airflow.

2. The coal mill moving and stationary ring structure according to claim 1, characterized in that, The airway (3) is divided into 3 to 5 stepped segments (31) along the airflow direction. The ratio of the flow cross-sectional area at the inlet to the flow cross-sectional area at the outlet of the airway (3) is 1.5 to 3.

0.

3. The coal mill moving and stationary ring structure according to claim 2, characterized in that, The abrupt step (32) is disposed on the inner ring wall (11) and / or the outer ring wall (12); The step height of the abrupt step (32) is 5% to 15% of the radial width of the airway (3) at the step location.

4. The coal mill moving and stationary ring structure according to claim 1, characterized in that, Along the airflow direction, the length of each of the stepped segments (31) accounts for 15% to 25% of the total length of the airway (3); The length of the step section (31) closest to the outlet of the airway (3) is less than the length of the step section (31) closest to the inlet of the airway (3).

5. The coal mill moving and stationary ring structure according to claim 1, characterized in that, The step surface (321) of the abrupt step (32) is provided with a plurality of flow-guiding ribs (322); the plurality of flow-guiding ribs (322) are arranged at intervals along the radial direction of the abrupt step (32), and the height of the flow-guiding ribs (322) is 30% to 50% of the step height.

6. The coal mill moving and stationary ring structure according to claim 1, characterized in that, The air passage (3) wall in the stepped section (31) is provided with drag-reducing microstructures (6); the drag-reducing microstructures (6) include multiple micro ridge-like protrusions arranged parallel to the airflow direction.

7. The coal mill moving and stationary ring structure according to claim 6, characterized in that, The ridge height of the micro-ridge protrusion is 0.1 mm to 0.5 mm, and the ridge distance between two adjacent micro-ridge protrusions is 0.5 mm to 2 mm.

8. The coal mill moving and stationary ring structure according to claim 1, characterized in that, The moving ring body (1) is divided into 12 to 16 moving ring segments (13) along the circumference. Adjacent moving ring segments (13) can be disassembled and spliced ​​to form a complete ring structure, and each moving ring segment (13) is interchangeable.

9. The coal mill moving and stationary ring structure according to claim 1, characterized in that, It also includes multiple air passage blades (5), the grinding disc (4) is provided with a groove, and the multiple air passage blades (5) are circumferentially spaced in the groove; the moving ring body (1) and the air passage blades (5) are integrally formed using high chromium wear-resistant alloy material.

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