A coal mill air-powder coupling device

Abstract

The application discloses a coal mill air-powder coupling device applied to the technical field of coal mills of thermal power plants, and the segmented dynamic ring impeller, the static ring pressing plate and the double-layer sealing unit are arranged, so that the coal powder and the airflow above the grinding disc can be effectively prevented from leaking downward to the primary air chamber, and the wear of the air ring is reduced; under the action of the inclined guide vane, the airflow jet angle, the stable radial velocity component and the vertical velocity component can be ensured while the outlet speed of the air ring is stabilized, the air-powder mixing degree and the lifting effect are improved, and the airflow uniformity is improved; in addition, through the inclined design of the primary sealing position and the secondary sealing position, the leakage of the micro powder in the airflow into the sealing cavity is effectively intercepted, and the wear of the contact position is effectively reduced; meanwhile, the secondary sealing position is converted from the hard contact into the elastic contact through the arrangement of the sandwiched embedded capsule, and the wear between the two is effectively reduced.

Description

Technical Field

[0001] This invention relates to the technical field of coal mills in thermal power plants, and in particular to a coal mill air-coal coupling device. Background Technology

[0002] Medium-speed coal mills (such as MPS, HP, and RP mills) are core equipment in the pulverizing system of coal-fired power plants. They crush raw coal through the grinding action of grinding rollers and grinding discs, and use hot primary air to dry and transport the pulverized coal. The air ring, as a key component of the coal mill, is responsible for generating high-speed airflow to lift and separate the pulverized coal; its performance directly affects the mill's output, efficiency, and operational stability. However, traditional air ring structures have the following drawbacks: First, the standardized design of the air ring fails to accurately match the actual coal type characteristics, primary air temperature, and grinding disc diameter, resulting in poor air-coal mixing and rapid attenuation of outlet airflow, leading to problems such as high emissions of coke and insufficient ventilation output. Second, wear is a significant issue: the air ring area is continuously eroded by high-speed, dust-laden airflow, especially the impeller parts of the stationary and moving rings, which are prone to localized blow-out damage. This not only shortens the equipment's lifespan but also increases maintenance costs due to frequent replacements. In addition, poor airflow uniformity is also a key defect. Traditional air rings cannot guarantee airflow uniformity along the circumference and vertical direction, which can easily lead to insufficient pulverized coal lifting force in local areas, resulting in pulverized coal falling, unstable material layer, and affecting grinding efficiency and uniformity of pulverized coal fineness.

[0003] To address the above problems, some improvements have been made in the existing technology, but some issues still remain: Chinese patent CN218654880U discloses a coal mill air ring device, which mainly focuses on the flow guiding form of the stationary ring, but neglects the overall sealing design, resulting in poor wear control. Chinese patent CN115672481A discloses a coal mill grinding coupling device and its usage method, emphasizing the improvement of the flow field stability in the middle section by the flow channel shape of the air ring. However, its air ring is a single piece and also neglects sealing design, making it prone to overall wear. Furthermore, even after localized wear, extensive replacement is still required, resulting in high maintenance costs. Summary of the Invention

[0004] 1. Technical problems to be solved The core of this invention lies in its segmented moving ring impeller and stationary ring pressure plate design, which solves the problem of high costs associated with replacing the entire impeller after partial wear in existing technologies. Simultaneously, the double-layer sealing unit forming a sealed cavity effectively prevents coal dust and airflow above the grinding disc from leaking downwards into the primary air chamber, thereby reducing wear on the air ring.

[0005] 2. Technical Solution To solve the above problems, the present invention adopts the following technical solution.

[0006] A coal mill air-coal coupling device includes a segmented air ring disposed between the inner wall of the coal mill and the outer wall of the grinding disc. The segmented air ring includes a moving ring impeller connected to the outer wall of the grinding disc and a double-layer sealing unit disposed between the moving ring impeller and the inner wall of the coal mill housing. The moving ring impeller includes multiple flow guiding units. Each flow guiding unit includes an inner impeller ring fixedly connected to the grinding disc by bolts, an outer impeller ring fixedly connected to the double-layer sealing unit, and multiple flow guiding blades fixedly connected between the inner and outer impeller rings. The multiple inner and outer impeller rings respectively form a complete ring. The double-layer sealing unit includes a stationary ring fixing plate and a stationary ring sealing ring fixedly connected to the inner wall of the coal mill casing, as well as a primary sealing ring and a secondary sealing ring fixedly connected to the outer end of the impeller outer ring. The stationary ring fixing plate is located above the stationary ring sealing ring, and the primary sealing ring is located above the secondary sealing ring. Multiple stationary ring pressure plates are fixedly connected to the upper end of the stationary ring fixing plate by bolts. The multiple stationary ring pressure plates form a complete ring. Two sets of stationary ring support plates are also welded to the inner wall of the coal mill casing, and there are multiple stationary ring support plates in each set. The two sets of stationary ring support plates are located below the stationary ring fixing plate and the stationary ring sealing ring, respectively, and are in contact with each other.

[0007] Furthermore, the primary sealing ring and the stationary ring fixing plate correspond to each other but do not contact each other. The upper surface of the primary sealing ring is flush with the upper end of the outer ring of the impeller, and the upper surface of the primary sealing ring is in contact with the lower surface of the stationary ring pressure plate. The two together form a primary sealing structure.

[0008] Furthermore, the secondary sealing ring is located on the upper surface of the stationary sealing ring, and the ends of the two overlap and contact each other. The secondary sealing ring and the stationary sealing ring form a secondary sealing structure, and the primary sealing structure and the secondary sealing structure form a sealing cavity.

[0009] Furthermore, the guide vane includes an upper guide vane and an inclined guide vane fixedly connected to one end of the upper guide vane below it, with the upper guide vane having an angle inclination range of -5° to 30°.

[0010] Optionally, the end faces of the stationary ring pressure plate and the primary sealing ring that come into contact with each other are inclined, with the inclined surfaces decreasing in the direction away from the outer ring of the impeller. The end faces of the stationary ring sealing ring and the secondary sealing ring that come into contact with each other are also inclined, with the inclined surfaces decreasing in the direction close to the outer ring of the impeller. A sandwich bladder is also provided between the stationary ring sealing ring and the secondary sealing ring. The sandwich bladder is saturated with air, and the outer surface of the sandwich bladder is coated with LINE-X coating.

[0011] Furthermore, the inclined portion of the stationary ring sealing ring is fixedly inlaid with a pre-avoidance layer, which is an elastic structure.

[0012] Furthermore, the sandwich-type capsule includes a wind-sensing layer located below the stationary sealing ring and the secondary sealing ring, a positioning layer fixedly attached to the secondary sealing ring, a wall-adhering layer in contact with and attached to the stationary sealing ring, a wind-gathering layer located above the stationary sealing ring, and a pressure-relief layer fixedly connected between the upper ends of the positioning layer and the wind-gathering layer. The middle parts of the wall-adhering layer and the positioning layer both span between the stationary sealing ring and the secondary sealing ring.

[0013] Furthermore, both the wind-sensing layer and the pressure relief layer are sealed elastic structures. The cross-section of the wind-sensing layer is semi-circular, the cross-section of the pressure relief layer is linear, the positioning layer is a rigid structure, the part of the wall-adhering layer that contacts the pre-avoidance layer is an elastic structure, and the rest of the wall-adhering layer is a rigid structure.

[0014] 3. Beneficial Effects Compared with the prior art, the advantages of this invention are: This solution addresses the high cost associated with replacing the entire impeller after partial wear, which is a problem in existing technologies, by using a segmented moving ring impeller and a stationary ring pressure plate. Simultaneously, the double-layer sealing unit forms a sealed cavity, effectively preventing coal dust and airflow above the grinding disc from leaking downwards into the primary air chamber, thereby reducing wear on the air ring.

[0015] By designing inclined and upper guide vanes, the airflow jet angle is ensured while maintaining a stable outlet velocity of the air ring, stabilizing the radial and vertical velocity components, improving air-powder mixing and lifting effect, and enhancing airflow uniformity. The inclined design of the primary and secondary seals effectively intercepts the leakage of fine powder from the airflow into the sealing cavity, thereby effectively reducing wear at the contact points. Simultaneously, the sandwiched bladder design allows for a certain degree of compression of the inclined surface of the stationary ring seal under the pressure of the primary airflow, creating a gap between the secondary and stationary ring seals. This transforms the hard contact between them into an elastic contact, effectively improving the sealing performance and reducing wear. Attached Figure Description

[0016] Figure 1 This is a partial sectional perspective view of the present invention; Figure 2 for Figure 1 A schematic diagram at point A in the middle; Figure 3 This is a perspective view of the present invention; Figure 4 This is a top view of the present invention; Figure 5 This is a cross-sectional schematic diagram of the double-layer sealing unit when both the primary sealing structure and the secondary sealing structure of the present invention are in horizontal contact; Figure 6 This is a perspective view of the flow guiding unit of the present invention; Figure 7This is an exploded view of the flow guiding unit of the present invention; Figure 8 This is a side view of the guide vane of the present invention; Figure 9 This is a cross-sectional schematic diagram of the double-layer sealing unit when both the primary sealing structure and the secondary sealing structure of the present invention are in inclined contact; Figure 10 This is a partial cross-sectional schematic diagram of the secondary sealing structure of the present invention; Figure 11 This is a schematic diagram of the present invention when the secondary sealing structures are converted into an elastic contact seal under the action of primary wind pressure.

[0017] The following are the labels in the diagram: 11 stationary ring pressure plate, 12 stationary ring fixing plate, 13 stationary ring sealing ring, 101 stationary ring support plate, 102 pre-avoidance layer, 2 guide unit, 21 impeller inner ring, 22 impeller outer ring, 23 guide vane, 231 upper guide vane, 232 inclined guide vane, 31 primary sealing ring, 32 secondary sealing ring, 4 sandwich bladder, 41 wind-sensing layer, 42 wall-attached layer, 43 wind-gathering layer, 44 pressure relief layer, 45 positioning layer. Detailed Implementation

[0018] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0019] Example 1:

[0020] Please see Figure 1 , Figure 3 , Figure 4 In the figure, a represents the coal mill outer shell, b represents the grinding disc, and c represents the primary air chamber. A coal mill air-powder coupling device includes a segmented air ring disposed between the inner wall of the coal mill and the outer wall of the grinding disc. The segmented air ring includes a moving ring impeller connected to the outer wall of the grinding disc and a double-layer sealing unit disposed between the moving ring impeller and the inner wall of the coal mill outer shell. Figures 6-7 The moving ring impeller includes multiple flow guiding units 2. Each flow guiding unit 2 includes an inner impeller ring 21 fixedly connected to the grinding disc by bolts, an outer impeller ring 22 fixedly connected to the double-layer sealing unit, and multiple flow guiding blades 23 fixedly connected between the inner impeller ring 21 and the outer impeller ring 22. The multiple inner impeller rings 21 and the multiple outer impeller rings 22 respectively form a complete ring. Both the moving ring impeller and the stationary ring pressure plate 11 are segmented structures, so that when wear occurs, only the corresponding part can be replaced, without the need for overall replacement, thereby effectively reducing its usage cost. like Figures 1-2The double-layer sealing unit includes a stationary ring fixing plate 12 and a stationary ring sealing ring 13 fixedly connected to the inner wall of the coal mill casing, and a primary sealing ring 31 and a secondary sealing ring 32 fixedly connected to the outer end of the impeller outer ring 22. The stationary ring fixing plate 12 is located above the stationary ring sealing ring 13, and the primary sealing ring 31 is located above the secondary sealing ring 32. Multiple stationary ring pressure plates 11 are fixedly connected to the upper end of the stationary ring fixing plate 12 by bolts, and the multiple stationary ring pressure plates 11 form a complete ring. The upper surface of the primary sealing ring 31 is flush with the upper end of the impeller outer ring 22, and the upper surface of the primary sealing ring 31 is in contact with the lower surface of the stationary ring pressure plate 11, and the two together form a primary sealing structure. The secondary sealing ring 32 is located above the stationary ring sealing ring. The upper surface of ring 13 overlaps and contacts each other at the ends. The secondary sealing ring 32 and the stationary sealing ring 13 form a secondary sealing structure. The primary sealing structure and the secondary sealing structure form a sealing cavity. The primary sealing structure can effectively intercept coal dust carried by the airflow at the edge of the grinding disc from entering between the coal mill and the grinding disc and into the primary air chamber. Some heavy, large, and humid particles that are difficult to be lifted by the airflow will fall into the primary air chamber along the gap inside the moving ring impeller and eventually fall into the slag discharge box inside. The secondary sealing structure can effectively intercept small particles carried by these particles from entering between the coal mill and the grinding disc, thereby effectively avoiding excessive wear of the segmented air ring.

[0021] like Figure 5 The inner wall of the coal mill shell is also welded with two sets of stationary ring support plates 101, and there are multiple stationary ring support plates 101 in each set. The two sets of stationary ring support plates 101 are located below the stationary ring fixing plate 12 and the stationary ring sealing ring 13 respectively and are in contact with each other. The two sets of stationary ring support plates 101 can be used to support the stationary ring fixing plate 12 and the stationary ring sealing ring 13 respectively, thereby effectively ensuring the stability of the segmented air ring. The primary sealing ring 31 and the stationary ring fixing plate 12 correspond to each other and do not contact each other, so that the stationary ring fixing plate 12 does not easily affect the rotation of the primary sealing ring 31 following the rotating ring impeller.

[0022] like Figure 8 The guide vane 23 includes an upper guide vane 231 and an inclined guide vane 232 fixedly connected to one end of the upper guide vane 231. The angle of the upper guide vane 231 is inclination range from -5° to 30°. The inclined design of the inclined guide vane 232 can effectively reduce the direct scouring of the impeller by the airflow. According to the actual coal type, the included angle between the upper guide vane 231 and the inclined guide vane 232 is designed to ensure the airflow jet angle while ensuring the stability of the air ring outlet velocity, stabilize the radial velocity component and the vertical velocity component, improve the air-powder mixing degree and lifting effect, improve the airflow uniformity, and thus reasonably match the airflow on the wind side with the gravity of the stones, reducing the amount of stone coal discharged.

[0023] It is worth noting that high-hardness wear-resistant materials are welded or inlaid on the windward side and end of the guide vane 23, which are prone to wear, to ensure its strength and make it less susceptible to wear.

[0024] In summary, this solution addresses the high cost associated with replacing the entire impeller after partial wear, as required in existing technologies, by using a segmented moving ring impeller and a stationary ring pressure plate 11. Simultaneously, the double-layer sealing unit forming a sealed cavity effectively prevents coal dust and airflow above the grinding disc from leaking downwards into the primary air chamber, thus reducing wear on the air ring. Furthermore, the design of the inclined guide vane 232 and the upper guide vane 231 ensures stable airflow jet angle while maintaining stable air ring outlet velocity, stabilizing radial and vertical velocity components, improving air-coal mixing and lifting effects, and enhancing airflow uniformity.

[0025] Example 2:

[0026] In this embodiment, the contact method between the stationary ring pressure plate 11 and the primary sealing ring 31, and between the stationary ring sealing ring 13 and the secondary sealing ring 32, is changed to an inclined contact, and the inclined angle of the contact surface is no greater than 30°. An interlayer insert 4 is added, and the rest is consistent with the embodiment 1.

[0027] like Figure 9 The contact surfaces of the stationary ring pressure plate 11 and the primary sealing ring 31 are both inclined, with the inclined surfaces decreasing in the direction away from the outer ring 22 of the impeller. Here, the primary airflow blowing out from the moving ring impeller blows away some coal dust. The airflow tends upward at the contact point between the stationary ring pressure plate 11 and the primary sealing ring 31, while the contact point is inclined downward, in the opposite direction to the airflow direction. This effectively reduces the occurrence of some fine powder seeping into the contact point with the airflow. The contact surfaces of the stationary ring sealing ring 13 and the secondary sealing ring 32 are also inclined, with the inclined surfaces decreasing in the direction away from the outer ring of the impeller. The direction of 22 is lowered, and a sandwich bladder 4 is also provided between the stationary ring sealing ring 13 and the secondary sealing ring 32. The sandwich bladder 4 is saturated with air, so that the sandwich bladder 4 is in a full and bulging state, so that it can form a large wrapping layer outside the contact area of ​​the stationary ring sealing ring 13 and the secondary sealing ring 32, thereby sealing the gap between the two. The outer surface of the sandwich bladder 4 is coated with LINE-X coating. The LINE-X coating can significantly improve the wear resistance and tensile strength of the sandwich bladder 4, so that the sandwich bladder 4 is not easily damaged by contact friction with the stationary ring sealing ring 13 when it rotates with the moving ring impeller.

[0028] The inclined portion of the stationary ring sealing ring 13 is fixedly inlaid with a pre-avoidance layer 102. The pre-avoidance layer 102 is an elastic structure. Due to the air saturation inside the interlayer capsule 4, there is a force that squeezes the interlayer capsule 4 outward, so that the pre-avoidance layer 102 can be subjected to a certain amount of compression and appear slightly compressed. This results in a certain small gap between the stationary ring sealing ring 13 and the secondary sealing ring 32, so that the friction between the secondary sealing ring 32 and the stationary ring sealing ring 13 is small when the impeller rotates.

[0029] like Figure 10 The interlayer capsule 4 includes a wind-sensing layer 41 located below the stationary sealing ring 13 and the secondary sealing ring 32, a positioning layer 45 fixedly attached to the secondary sealing ring 32, a wall-adhering layer 42 in contact with and attached to the stationary sealing ring 13, a wind-gathering layer 43 located above the stationary sealing ring 13, and a pressure-relief layer 44 fixedly connected between the upper ends of the positioning layer 45 and the wind-gathering layer 43. The middle parts of the wall-adhering layer 42 and the positioning layer 45 both span between the stationary sealing ring 13 and the secondary sealing ring 32. The wind-sensing layer 41 and the pressure-relief layer 44 are both sealed elastic structures. The cross-section of the wind-sensing layer 41 is semi-circular, and the cross-section of the pressure-relief layer 44 is linear. The positioning layer 45 is a rigid structure. The part of the wall-adhering layer 42 that contacts the pre-avoidance layer 102 is an elastic structure, and the rest of the wall-adhering layer 42 is a rigid structure.

[0030] During use, under the pressure of the primary air in the primary air chamber, the wind-sensing layer 41 deforms towards the contact point between the stationary ring sealing ring 13 and the secondary sealing ring 32, causing the compressed air inside to gather towards that point. This increases the compressive force on the pre-avoidance layer 102, making its compression more pronounced and creating a noticeable gap. At this time, as the secondary sealing ring 32 rotates with the impeller, the interlayer insert 4 also rotates with it. This changes the hard contact friction between the stationary ring sealing ring 13 and the secondary sealing ring 32 in Example 1 to elastic contact friction between the interlayer insert 4 and the pre-avoidance layer 102. Furthermore, under the action of wind pressure, the surface compression force between the interlayer insert 4 and the stationary ring sealing ring 13 is greater, and the fit is higher. Thus, even when the two are not in contact, the sealing performance is effectively guaranteed. This effectively prevents coal dust and airflow above the grinding disc from leaking downwards into the primary air chamber, and also effectively reduces the entry of small particles such as stones and coal blocks into the sealing cavity. This effectively ensures the smoothness of the rotating ring impeller and reduces friction damage.

[0031] The inclined design of the primary and secondary sealing points effectively intercepts the leakage of micro-powder in the airflow into the sealing cavity, thereby effectively reducing wear at the contact points. Simultaneously, in conjunction with the sandwiched bladder 4, the inclined surface of the stationary sealing ring 13 is compressed under the pressure of the primary airflow, creating a gap between the secondary sealing ring 32 and the stationary sealing ring 13. This transforms the rigid contact between them into an elastic contact, effectively improving the sealing performance and reducing wear. The above description is merely a preferred embodiment of the present invention and encompasses all protection scope of the invention. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this invention, based on the technical solution and its improved concepts, should be covered within the protection scope of this invention.

Claims

1. A mill air coupling device, comprising a segmented air ring arranged between the inner wall of the mill and the outer wall of the mill disc, the segmented air ring comprising a moving ring impeller connected to the outer wall of the mill disc and a double-layer sealing unit arranged between the moving ring impeller and the inner wall of the mill housing, characterized in that: The moving ring impeller includes multiple flow guiding units (2). Each flow guiding unit (2) includes an inner impeller ring (21) fixedly connected to the grinding disc by bolts, an outer impeller ring (22) fixedly connected to the double-layer sealing unit, and multiple flow guiding blades (23) fixedly connected between the inner impeller ring (21) and the outer impeller ring (22). The multiple inner impeller rings (21) and the multiple outer impeller rings (22) respectively form a complete ring. The double-layer sealing unit includes a stationary ring fixing plate (12) and a stationary ring sealing ring (13) fixedly connected to the inner wall of the coal mill shell, and a primary sealing ring (31) and a secondary sealing ring (32) fixedly connected to the outer end of the impeller outer ring (22). The stationary ring fixing plate (12) is located above the stationary ring sealing ring (13), and the primary sealing ring (31) is located above the secondary sealing ring (32). Multiple stationary ring pressure plates (11) are fixedly connected to the upper end of the stationary ring fixing plate (12) by bolts. The multiple stationary ring pressure plates (11) form a complete ring. Two sets of stationary ring support plates (101) are also welded to the inner wall of the coal mill shell, and there are multiple sets of each set of stationary ring support plates (101). The two sets of stationary ring support plates (101) are located below the stationary ring fixing plate (12) and the stationary ring sealing ring (13) respectively and are in contact with each other. The end faces of the stationary ring pressure plate (11) and the primary sealing ring (31) that come into contact with each other are inclined, and the inclined surfaces decrease in the direction away from the outer ring (22) of the impeller. The end faces of the stationary ring sealing ring (13) and the secondary sealing ring (32) that come into contact with each other are also inclined, and the inclined surfaces decrease in the direction close to the outer ring (22) of the impeller. A sandwich bladder (4) is also provided between the stationary ring sealing ring (13) and the secondary sealing ring (32). The sandwich bladder (4) is saturated with air, and the outer surface of the sandwich bladder (4) is coated with LINE-X coating. The inclined portion of the stationary sealing ring (13) is fixedly inlaid with a pre-avoidance layer (102), which is an elastic structure. The interlayer capsule (4) includes a wind-sensing layer (41) located below the stationary sealing ring (13) and the secondary sealing ring (32), a positioning layer (45) fixedly attached to the secondary sealing ring (32), a wall-adhering layer (42) in contact with the stationary sealing ring (13), a wind-gathering layer (43) located above the stationary sealing ring (13), and a pressure-relief layer (44) fixedly connected between the upper ends of the positioning layer (45) and the wind-gathering layer (43). The middle portions of the wall-adhering layer (42) and the positioning layer (45) both span between the stationary sealing ring (13) and the secondary sealing ring (32).

2. The coal mill air-coal coupling device according to claim 1, characterized in that: The primary sealing ring (31) and the stationary ring fixing plate (12) correspond to each other and do not contact each other. The upper surface of the primary sealing ring (31) is flush with the upper end of the outer ring (22) of the impeller. The upper surface of the primary sealing ring (31) is in contact with the lower surface of the stationary ring pressure plate (11), and the two form a primary sealing structure.

3. The coal mill air-coal coupling device according to claim 1, characterized in that: The secondary sealing ring (32) is located on the upper surface of the stationary sealing ring (13), and the ends of the two overlap and contact each other. The secondary sealing ring (32) and the stationary sealing ring (13) form a secondary sealing structure, and the primary sealing structure and the secondary sealing structure form a sealing cavity.

4. The coal mill air-coal coupling device according to claim 1, characterized in that: The guide vane (23) includes an upper guide vane (231) and an inclined guide vane (232) fixedly connected below one end of the upper guide vane (231). The angle of the upper guide vane (231) is inclination range from -5° to 30°.

5. A coal mill air-coal coupling device according to claim 1, characterized in that: The wind-sensing layer (41) and the pressure relief layer (44) are both sealed elastic structures. The cross-section of the wind-sensing layer (41) is semi-circular, and the cross-section of the pressure relief layer (44) is straight. The positioning layer (45) is a rigid structure. The part of the wall-adhering layer (42) that contacts the pre-avoidance layer (102) is an elastic structure, and the rest of the wall-adhering layer (42) is a rigid structure.

Images