A shaft seal for a coal mill drive shaft

Abstract

This invention discloses a shaft seal for a coal mill drive shaft, comprising a drive shaft, a raw coal mill reducer, and a raw coal mill hopper. The output end of the raw coal mill reducer is connected to the drive shaft via a first bolt. The drive shaft is connected to the bottom plate of the raw coal mill hopper via a connecting support mechanism. A sealing assembly is provided between the connecting support mechanism and the drive shaft. The suspended floating seal design adopts a contact type arrangement, which is reasonable and compact in process, wear-resistant, always in close contact with the drive shaft, and easy to disassemble. It not only eradicates the persistent problem of large-scale coal powder leakage from the drive shaft, but also reduces equipment maintenance costs and labor costs, improves equipment efficiency, requires less maintenance, is convenient to repair, and has a long maintenance cycle. It not only eradicates the persistent problem of large-scale coal powder leakage from the drive shaft, improves the working environment, and reduces labor intensity, but also achieves significant economic benefits in terms of cost saving and work efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of mechanical seals, specifically a shaft seal for a coal mill drive shaft. Background Technology

[0002] The traditional coal mill drive shaft sealing structure in the pulverizing system of a thermal power plant boiler uses a non-contact labyrinth seal. After several years of operational experience, this structure has revealed significant shortcomings. Vibration caused by machining concentricity or other factors during operation disrupts the original clearance between the toothed seal ring and the drive shaft, leading to friction and wear. The designed seal clearance (0.20 mm-0.40 mm) cannot be maintained, directly resulting in an increased seal clearance and insufficient sealing pressure, causing coal dust leakage from the drive shaft seal. This significant coal dust leakage further increases the clearance between the toothed seal ring and the drive shaft, creating a vicious cycle. Ultimately, this leads to substantial coal dust leakage from the drive shaft seal, severely impacting on-site production.

[0003] According to application number 201821212116.1, a medium-speed coal mill drive shaft sealing assembly includes a grinding bowl, an outer gas seal, an inner gas seal, and a skirt. The inner gas seal is composed of a longitudinal vertical plate and a transverse horizontal plate, which are L-shaped. The top end face of the horizontal plate is composed of a first slope and a first plane, with the first plane located between the first slope and the vertical plate. The skirt has a top edge and a bottom edge. The top edge rests against the bottom of the bell mouth of the grinding bowl. The bottom edge has a third plane, a second slope corresponding to the first slope, and a second plane corresponding to the first plane. The second slope is located between the third plane and the second plane. The skirt and the inner gas seal are assembled such that the first slope and the second slope, and the first plane and the second plane are assembled to form a sealing structure. The cavity formed after the grinding bowl, the outer gas seal, the inner gas seal, and the skirt are assembled is a sealed air chamber.

[0004] The aforementioned coal mill drive shaft seal increases the length of the sealing surface, providing a certain degree of sealing. However, this only increases the length of the seal without making any substantial changes. During operation, vibrations caused by machining concentricity or other factors can disrupt the original gap between the toothed seal ring and the drive shaft, leading to friction and wear. This compromises the sealing gap, prevents the establishment of sufficient sealing pressure, and causes coal powder to leak from the drive shaft seal. Therefore, further addressing the issues of "running, leaking, dripping, and seeping" in the pulverizing system, improving the civilized production and equipment reliability of the boiler pulverizing system, and conducting technical research on the sealing structure of the high-speed coal mill drive shaft in the boiler pulverizing system are essential. Summary of the Invention

[0005] The present invention mainly provides a shaft seal for a coal mill drive shaft to solve the technical problems mentioned in the background art.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A shaft seal for a coal mill drive shaft includes a drive shaft, a raw coal mill reducer, and a raw coal mill chamber. The output end of the raw coal mill reducer is connected to the drive shaft via a first bolt. The drive shaft is connected to the bottom plate of the raw coal mill chamber via a connecting support mechanism. A sealing assembly is provided between the connecting support mechanism and the drive shaft.

[0008] Preferably, the sealing assembly includes sealing rings, and a total of twelve sealing rings are provided. Each sealing ring has a groove, and the sealing rings are evenly distributed on the outer circumferential wall of the bottom of the drive shaft. The grooves of the sealing rings are connected by springs.

[0009] Preferably, two connecting support mechanisms are provided, symmetrically located on both sides of the bottom of the drive shaft. Each connecting support mechanism includes a first connecting component and a second connecting component. Each first connecting component includes a first support plate, which is L-shaped. One top end of the first support plate abuts against the bottom of the wing plate on the top circumferential wall of the drive shaft, and the other end of the first support plate abuts against the bottom outer wall of the drive shaft. A second support plate, which is connected to the original coal mill chamber bottom plate, is connected to the top corner of each first support plate. The second support plate is connected to the original coal mill chamber bottom plate by a second bolt.

[0010] Preferably, an adjusting shim is fitted on the outer circumferential wall of the second bolt located between the second support plate and the original coal mill bottom plate.

[0011] Preferably, the second connecting component includes a third support plate, which is arranged in an inverted L-shape. The top of the third support plate abuts against the bottom of the first support plate. A first connecting plate is connected to the bottom of the third support plate near the drive shaft. A cavity for accommodating the sealing component is formed between the third support plate and the first connecting plate. The sealing component is located on the outer circumferential wall of the bottom of the drive shaft inside the cavity.

[0012] Preferably, a first slag-blocking ring is provided on the outer wall between the top of the first support plate and the drive shaft. The first slag-blocking ring is fixed to the drive shaft by a third bolt. A second slag-blocking ring is provided at the top of the first support plate at the end away from the first slag-blocking ring. The second slag-blocking ring is connected to the drive shaft.

[0013] Preferably, a slag discharge hole is formed through the first support plate.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. The floating seal design adopts a contact type, which is reasonable and compact in process;

[0016] 2. Due to the new floating seal technology, it has the characteristics of wear resistance, always in close contact with the drive shaft, and easy disassembly. It not only eradicates the stubborn problem of large-scale leakage of coal powder from the drive shaft, but also reduces equipment maintenance costs and labor costs, and improves equipment utilization efficiency.

[0017] 3. The new wear-resistant material used in the suspended floating seal technology—antimony-impregnated graphite carbon crystal ring (sealing ring)—is a high-temperature resistant, wear-resistant, and self-lubricating solid material with a service life of 20,000 to 25,000 hours, which can ensure the long-term reliable operation of the coal mill.

[0018] 4. Low maintenance, convenient repair, and long service life;

[0019] 5. Based on the above characteristics, the adoption of the new floating seal technology can not only eradicate the persistent problem of large-scale coal powder leakage from the drive shaft, improve the working environment, and reduce labor intensity, but also achieve significant economic benefits in terms of cost saving and work efficiency improvement.

[0020] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0021] Figure 1 This is the overall front view of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the present invention;

[0023] Figure 3 This is a cross-sectional view of the sealing ring of the present invention;

[0024] Figure 4 This is a schematic diagram of the connection support mechanism of the present invention.

[0025] Figure descriptions: 1. Drive shaft; 2. Raw coal mill reducer; 3. Raw coal mill chamber; 4. First bolt; 5. Connecting support mechanism; 51. First support plate; 52. Second support plate; 53. Second bolt; 54. Adjusting shim; 55. Third support plate; 56. First connecting plate; 6. Sealing assembly; 61. Sealing ring; 62. Spring; 7. First slag-blocking ring; 71. Third bolt; 72. Second slag-blocking ring. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Please refer to the appendix carefully. Figure 1-4 As shown, a shaft seal for a coal mill drive shaft includes a drive shaft 1, a raw coal mill reducer 2, and a raw coal mill chamber 3. The output end of the raw coal mill reducer 2 is connected to the drive shaft 1 by a first bolt 4. The drive shaft 1 is connected to the bottom plate of the raw coal mill chamber 3 by a connecting support mechanism 5. A sealing assembly 6 is provided between the connecting support mechanism 5 and the drive shaft 1. The sealing assembly 6 includes sealing rings 61. A total of twelve sealing rings 61 are provided. Each sealing ring 61 has a groove. The multiple sealing rings 61 are evenly distributed on the outer circumferential wall at the bottom of the drive shaft 1. The grooves of the multiple sealing rings 61 are connected by springs 62.

[0030] It should be noted that in this embodiment, the sealing ring 61 is made of a novel anti-wear material, an antimony-impregnated graphite carbon crystal ring, which has the advantages of high temperature resistance, wear resistance, and self-lubrication. The carbon crystal ring is processed into the sealing ring 61. A groove is designed at the rear of the sealing ring 61. Twelve sealing rings 61 are arranged around the outer circumference of the drive shaft 1, and their rear ends are fixed together by springs 62. Due to the action of the springs 62 in the groove, when the drive shaft 1 rotates, the sealing rings 61 can swing within the grooves of the third support plate 55 and the first connecting plate 56 with the swing of the drive shaft 1, and always maintain contact with the drive shaft 1, thus achieving a reliable seal. This not only eradicates the persistent problem of large-scale leakage of coal powder from the drive shaft 1, but also reduces equipment maintenance costs and labor costs, and improves equipment utilization efficiency.

[0031] Please refer to the appendix carefully. Figure 1 , 2 As shown in Figure 4, two connecting support mechanisms 5 are provided, symmetrically located on both sides of the bottom of the drive shaft 1. Each connecting support mechanism 5 includes a first connecting component and a second connecting component. Each first connecting component includes a first support plate 51, which is L-shaped. A slag discharge hole is provided through the first support plate 51. One top end of the first support plate 51 abuts against the bottom of the wing plate on the top circumferential wall of the drive shaft 1. A first slag-blocking ring 7 is provided on the outer wall between the top of the first support plate 51 and the drive shaft 1. The first slag-blocking ring 7 passes through... The third bolt 71 is fixed to the drive shaft 1. The first baffle ring 7 is connected to the drive shaft 1 and rotates with the drive shaft 1, sealing the contact point between the drive shaft 1 and the top of the first support plate 51 to prevent excessive leakage of coal dust. The other end of the first support plate 51 abuts against the bottom outer wall of the drive shaft 1. A second baffle ring 72 is provided at the top of the end of the first support plate 51 away from the first baffle ring 7. The second baffle ring 72 is connected to the drive shaft 1 and seals the contact point between the other end of the first support plate 51 and the drive shaft 1 to prevent excessive leakage of coal dust. To prevent leakage, each first support plate 51 is connected at its apex to a second support plate 52, which is connected to the original bottom plate of the coal mill chamber 3. The second support plate 52 is connected to the original bottom plate of the coal mill chamber 3 by a second bolt 53. An adjusting shim 54 is fitted on the outer circumferential wall of the second bolt 53 located between the second support plate 52 and the original bottom plate of the coal mill chamber 3. The second connecting assembly includes a third support plate 55, which is arranged in an inverted L-shape. The top of the third support plate 55 abuts against the bottom of the first support plate 51 and is fixed by bolts. The bottom of the third support plate 55 is close to the drive shaft 1. A first connecting plate 56 is connected to one side, and a cavity for accommodating the sealing assembly 6 is formed between the third support plate 55 and the first connecting plate 56. The sealing assembly 6 is located on the outer circumferential wall of the bottom of the drive shaft 1 inside the cavity. When the drive shaft 1 rotates, the sealing ring 61 can swing with the swing of the drive shaft 1 in the groove of the third support plate 55 and the first connecting plate 56, and always maintain contact with the drive shaft 1, thus achieving a reliable seal. This not only eradicates the stubborn problem of large-scale leakage of coal powder from the drive shaft 1, but also reduces equipment maintenance costs and labor costs, and improves equipment utilization efficiency.

[0032] The specific process of this invention is as follows:

[0033] The original non-contact labyrinth seal structure was removed. Due to varying degrees of wear at the original seal between the old drive shaft 1 and the toothed seal ring, the repair method was to process it on-site. The turning device of the coal mill reducer was used to drive the coal mill drive shaft 1 to rotate at low speed. A tool holder was designed and installed on-site, and the lead screw was driven by a motor to automatically feed the tool. The worn part of the original drive shaft 1 was repaired, and the diameter was turned from the original Φ1600mm to about Φ1594mm-1596mm; the height was about 200mm-220mm. Polishing was then performed to make the roughness of the shaft at this point reach about 1.6. Install the second slag-blocking ring 72 and the connecting support mechanism 5. The sealing gap between the first support plate 51 and the upper moving shaft 1 grinding table is 1+0.5mm. At the same time, adjust the concentricity of the first support plate 51 and the drive shaft 1 to ≤0.6mm and the perpendicularity to ≤1.2mm. Install the first slag-blocking ring 7 and the third support plate 55 to form an air seal chamber. When installing the air seal chamber, first install 3 / 4 of the circumference of the air seal chamber. Push the carbon crystal ring sealing ring 61 into the air seal chamber from the opening of the first connecting plate 56 until the circumference is reached. Then install the remaining air seal chamber, first connecting plate 56 and third support plate 55 and fix them with bolts. At the same time, adjust the concentricity of the air seal chamber with the drive shaft 1 to ≤0.6mm. The installation is complete.

[0034] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A shaft seal for a coal mill drive shaft, comprising a drive shaft (1), a raw coal mill reducer (2), and a raw coal mill chamber (3), characterized in that... The output end of the raw coal mill reducer (2) is connected to the transmission shaft (1) by the first bolt (4). The transmission shaft (1) is connected to the bottom plate of the raw coal mill chamber (3) by the connecting support mechanism (5). A sealing assembly (6) is provided between the connecting support mechanism (5) and the transmission shaft (1). The sealing assembly (6) includes a sealing ring (61), and there are twelve sealing rings (61) in total. Each sealing ring (61) has a groove. The multiple sealing rings (61) are evenly distributed on the outer circumferential wall at the bottom of the transmission shaft (1). The grooves of the multiple sealing rings (61) are connected by springs (62). There are two connecting support mechanisms (5). The connecting support mechanisms (5) are symmetrically located on both sides of the bottom of the transmission shaft (1). Each connecting support mechanism (5) includes a first connecting component and a second connecting component. Each first connecting component includes a first support plate (51). The first support plate (51) is arranged in an L-shape. One end of the top of the first support plate (51) abuts against the bottom of the wing plate on the top circumferential wall of the transmission shaft (1). The other end of the first support plate (51) abuts against the bottom outer wall of the transmission shaft (1). A second support plate (52) connected to the bottom plate of the original coal mill chamber (3) is connected at the top corner of each first support plate (51). The second support plate (52) is connected to the bottom plate of the original coal mill chamber (3) by a second bolt (53).

2. The shaft seal for a coal mill drive shaft according to claim 1, characterized in that, An adjusting shim (54) is fitted on the outer circumferential wall of the second bolt (53) located between the second support plate (52) and the bottom plate of the original coal mill chamber (3).

3. A shaft seal for a coal mill drive shaft according to claim 1, characterized in that, The second connecting component includes a third support plate (55), which is arranged in an inverted L-shape. The top of the third support plate (55) abuts against the bottom of the first support plate (51). A first connecting plate (56) is connected to the bottom of the third support plate (55) near the drive shaft (1). A cavity for accommodating the sealing component (6) is formed between the third support plate (55) and the first connecting plate (56). The sealing component (6) is located on the outer circumferential wall of the bottom of the drive shaft (1) inside the cavity.

4. A shaft seal for a coal mill drive shaft according to claim 2, characterized in that, A first slag-blocking ring (7) is provided on the outer wall between the top of the first support plate (51) and the transmission shaft (1). The first slag-blocking ring (7) is fixed to the transmission shaft (1) by a third bolt (71). A second slag-blocking ring (72) is provided on the top of the end of the first support plate (51) away from the first slag-blocking ring (7). The second slag-blocking ring (72) is connected to the transmission shaft (1).

5. A shaft seal for a coal mill drive shaft according to claim 3, characterized in that, The first support plate (51) has a through-hole for slag discharge.

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