Medium-speed mill base sealing device

Abstract

The utility model relates to a medium-speed mill base sealing device, which comprises a movable sealing ring, the top of which is connected with a driving disc and moves along with the driving disc; the bottom of the static sealing ring is connected with the shell bottom plate; the movable sealing ring extends downwards, the static sealing ring extends upwards, the overlapped position of the movable sealing ring and the static sealing ring forms a big-end-up annular area, the third annular gap is located below the annular area, and the annular area is communicated with the sealing cavity; the carbon ring body is fixed to the bottom of the static sealing ring through a carbon ring pressing plate, and the carbon ring body and the transmission disc are tightly attached in the radial direction to form contact type sealing. The bottom of the static sealing ring is connected with a sealing air pipe, and the sealing air pipe communicates with the sealing cavity. Pulverized coal in a primary air chamber is prevented from entering a sealing cavity, the problem of abrasion of a carbon ring of an original engine base sealing structure is fundamentally solved, and therefore it is guaranteed that the engine base sealing structure is in an effective sealing state for a long time, and the engine base sealing structure has important significance on solving the problems that an existing medium-speed coal mill is short in service life, large in overhaul and maintenance difficulty and the like. Wide application prospects are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of powder making and grinding, and more specifically to a sealing device for a medium-speed grinding machine seat. Background Art

[0002] The structure of the medium speed coal mill is shown in the attached Figure 2 The transmission disc 10 is installed at the output end of the main reducer 11. The main reducer 11, driven by the main motor 12, drives the transmission disc 10 to rotate horizontally around the center line L of the coal mill. The shell 13, the transmission disc 10, the dynamic air ring 14, the static air ring 15 and the machine base sealing device 16 together form a primary air chamber 17. The hot primary air enters the primary air chamber 17 from the primary air inlet 171, passes through the annular dynamic air ring 14 and enters the coal mill upward. The hot primary air usually has a temperature of about 300°C and a pressure of about 7kpa higher than the atmospheric pressure. In order to prevent the hot primary air from leaking from the primary air chamber 17 to the outside of the coal mill, a machine base sealing device 16 is installed at the dynamic and static combination position of the shell 13 and the transmission disc 10.

[0003] The base seal is a device that uses sealing air to seal. Figure 3 . The base sealing device 16 includes a sealing ring 161, a carbon ring 162, a pressure plate 163 and a sealing air duct 164. The sealing ring 161 is installed on the bottom plate 131 of the outer shell, and forms a first annular gap A and a second annular gap B with the transmission disc 10. The carbon ring 162 is installed below the sealing ring 161 through the pressure plate 163. The carbon ring 162 is pressed against the outer cylindrical surface of the transmission disc 10 to form a contact seal. The sealing ring 161, the transmission disc 10 and the carbon ring 162 together form an annular sealed chamber. The sealing air duct 164 is installed at the bottom of the sealing ring 161. The sealing air enters the sealed chamber through the sealing air duct 164, so that the pressure in the sealed chamber is higher than the pressure in the primary air chamber 17. As a result, the high-temperature primary air in the primary air chamber cannot enter the sealed chamber, thereby achieving a sealing effect on the hot primary air and preventing the primary air from leaking out of the coal mill.

[0004] However, in actual use, seal failure often occurs, the contact position of the transmission disc 10 and the carbon ring 162 is severely worn, and the hot primary air carries coal powder from the first annular gap A to the outside of the coal mill, which not only causes environmental pollution at the production site, but also brings safety hazards. The location of the machine base seal device 16 is very inconvenient for inspection and maintenance. Each time the machine base seal is replaced, the coal mill must be stopped, and the grinding rollers, transmission discs, and scrapers inside the coal mill must be removed before maintenance operations can be performed. The inspection time is long, the disassembly and reinstallation workload is large, and the inspection and maintenance costs are increased.

[0005] Therefore, how to improve the reliability of the above-mentioned machine base seal and facilitate maintenance is an urgent problem that those skilled in the art need to solve. Utility Model Content

[0006] Therefore, the purpose of the utility model is to provide a medium-speed mill base sealing device to solve the problem of failure of the base sealing device in the prior art.

[0007] The technical solution of the utility model is a medium-speed mill seat sealing device, comprising:

[0008] A dynamic sealing ring, the top of which is connected to the transmission disc and moves with it;

[0009] A static sealing ring, the bottom of which is connected to the bottom plate of the housing; the dynamic sealing ring extends downward, the static sealing ring extends upward, the overlapping position of the dynamic sealing ring and the static sealing ring forms an annular area with a larger top and a smaller bottom, the third annular gap is located below the annular area, and the annular area is communicated with the sealing chamber;

[0010] A carbon ring body, wherein the carbon ring body is fixed to the bottom of the static sealing ring through a carbon ring pressure plate, and the carbon ring body is radially close to the transmission disk to form a contact seal;

[0011] A sealed air duct is connected to the bottom of the static sealing ring, and the sealed air duct is communicated with the sealed chamber.

[0012] According to the technical solution of the utility model, the dynamic sealing ring is connected with a first annular segment, a first conical segment and a first cylindrical segment in sequence from top to bottom. The top of the first annular segment forms a plane and is rigidly connected to the transmission disc and rotates with the transmission disc.

[0013] According to the technical solution of the utility model, the first annular segment extends inwardly relative to the first conical segment to form a plane, and the first conical segment gradually extends outwardly relative to the first cylindrical segment to form a first taper.

[0014] According to the technical solution of the utility model, the angle between the first conical section and the first cylindrical section is 150°-180°.

[0015] According to the technical solution of the utility model, the static sealing ring is connected with a second conical section, a second cylindrical section and a second annular section in sequence from top to bottom, the second conical section has a taper direction opposite to that of the first conical section, and forms a V-shaped annular area, a third annular gap is formed between the first cylindrical section and the second cylindrical section, the second annular section is rigidly connected to the bottom plate of the outer shell, the carbon ring body is fixed on the second annular section, and the sealing air duct is connected to the bottom of the second annular section.

[0016] According to the technical solution of the utility model, the second conical segment gradually forms a second taper inwardly relative to the second cylindrical segment, and the second annular segment extends inwardly relative to the second cylindrical segment to form an annular plane.

[0017] According to the technical solution of the utility model, the angle between the second conical section and the second cylindrical section is 145°-150°.

[0018] According to the technical solution of the utility model, the width of the third annular gap is 2-5 mm.

[0019] According to the technical solution of the utility model, the horizontal distance of the V-shaped annular area increases with the increase of height.

[0020] According to the technical solution of the utility model, the flow cross-sectional area of ​​the annular zone is larger than the flow cross-sectional area of ​​the third annular gap.

[0021] It can be seen from the above technical solution that compared with the prior art, the utility model has the following beneficial effects:

[0022] The utility model has an additional annular area with a larger top and a smaller bottom in the sealed chamber. When the pressure fluctuation in the primary air chamber causes the hot primary air to carry coal powder into the sealed chamber at a certain moment in a part of the third annular gap, for the original machine base sealing structure, the coal powder carried into the sealed chamber by the hot primary air is deposited in the sealed chamber. For the machine base sealing device provided by the utility model, the coal powder carried into the sealed chamber by the hot primary air is deposited in the annular area with a larger top and a smaller bottom. When the pressure of the sealed chamber at this position is higher than the pressure of the primary air chamber at the next moment, the coal powder deposited in the annular area with a larger top and a smaller bottom is blown back into the primary air chamber.

[0023] The utility model prevents coal powder in the primary air chamber from entering the sealing chamber without increasing the sealing air pressure through structural optimization, fundamentally solves the wear problem of the carbon ring of the original machine base sealing structure, thereby ensuring that the machine base seal is in an effective sealing state for a long time. This is of great significance for solving the current problems of short machine base seal life and great difficulty in overhaul and maintenance of medium-speed coal mills, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 A structural schematic diagram of a medium-speed mill seat sealing device provided by the utility model;

[0026] Figure 2 A schematic diagram of a medium-speed coal mill using a base sealing structure of the prior art;

[0027] Figure 3 It is a schematic diagram of the machine base sealing structure of the prior art;

[0028] Figure 4 This is a top view of the primary air chamber;

[0029] Figure 5 A three-dimensional cross-sectional view of a dynamic sealing ring of a medium-speed mill seat sealing device provided by the utility model;

[0030] Figure 6 A three-dimensional cross-sectional view of a static sealing ring of a medium-speed mill seat sealing device provided by the utility model;

[0031] Figure 7 It is a cross-sectional view of the annular area formed by the dynamic sealing ring and the static sealing ring. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0033] The inventor of the present invention has analyzed the structure of the existing sealing device and the sealing failure phenomenon, and has found that the sealing device of the present invention is Figure 2-4 It is believed that the seal failure process is that first, coal powder enters the sealed chamber, and then the coal powder reaches the joint position of the carbon ring 162 and the transmission disc 10. Since the transmission disc 10 is rotating, the coal powder causes wear of the transmission disc 10 and the carbon ring 162. As the wear intensifies, a gap begins to appear between the carbon ring 162 and the transmission disc 10. The sealing air in the sealed chamber leaks outward from the gap. At this time, a small amount of coal powder leakage and sealing air leakage can be observed outside the coal mill, but there is no hot primary air leakage. As the sealing air leakage increases, the pressure in the sealed chamber gradually decreases, which causes more coal powder to enter the sealed chamber. The entry of more coal powder further intensifies the wear of the transmission disc 10 and the carbon ring 162, and increases the gap between the carbon ring 162 and the transmission disc 10. This vicious cycle eventually leads to complete failure of the seal and leakage of a large amount of hot primary air and coal powder.

[0034] The above analysis shows that the most critical issue in the entire sealing failure process is how the coal powder entered the sealing chamber. If the coal powder did not enter the sealing chamber, the subsequent chain reaction would not occur. The pressure in the sealing chamber is higher than the pressure in the primary air chamber. The coal mill operation regulations require that the pressure of the sealing air is at least 2kpa higher than the primary air pressure. According to the above requirements, only the sealing air in the sealing chamber can enter the primary air chamber through the second annular gap B, and the phenomenon of hot primary air carrying coal powder backflow into the sealing chamber will not occur.

[0035] The primary air chamber 17 is an annular area between the coal mill housing 13 and the drive plate 10, and the primary air inlet 171 is on the left side. Figure 4 The primary air outlet is the dynamic air ring above the primary air chamber, see attached Figure 2 , four scraper devices 18 are installed on the transmission disc 10 and rotate with the transmission disc 10. Through further structural analysis of the primary air chamber 17, it can be concluded that the hot primary air enters the primary air chamber 17 from the primary air inlet 171, and then is discharged from the primary air chamber from the moving air ring 14. The flow field formed in the primary air chamber during this process is uneven. In addition, due to the influence of the scraper device 18, the pressure field in the primary air chamber 17 is constantly fluctuating, and correspondingly, the pressure outside the second annular gap B is also constantly fluctuating. Since the sealing air inlet of the sealing chamber is also local relative to the annular sealing chamber, the flow field formed by the sealing air in the sealing chamber is also uneven, and correspondingly, the pressure inside the second annular gap B is uneven.

[0036] Combining the above two situations may lead to a situation where the average pressure in the sealed chamber is higher than the average pressure in the primary air chamber, but at a certain moment, at a certain position of the second annular gap B, the pressure in the sealed chamber is lower than the pressure in the primary air chamber, and the hot primary air will carry the coal powder into the sealed chamber. Once the coal powder enters the sealed chamber, it will settle and cannot be discharged, eventually causing the carbon ring 162 and the transmission disc 10 to be worn until the seal fails.

[0037] Therefore, as long as the problem of coal powder entering the sealed chamber is solved, the problem of seal failure will also be solved.

[0038] The inventor of the utility model determined through analysis that increasing the sealing air pressure to increase the pressure difference between the sealing chamber and the primary air chamber can ensure that all parts of the second annular gap B are in a sealed state at all times; however, this will increase the pressure and flow of the sealing air, resulting in a significant increase in the sealing cost.

[0039] Through the diligent research of the inventor of the utility model, the utility model provides another solution to solve the problem of coal powder entering the sealed chamber without increasing the sealing air pressure.

[0040] The technical solution of the utility model is a medium-speed mill seat sealing device, see attached Figure 1 , including: a dynamic sealing ring 20, the top of which is connected to the transmission disk 10 and moves with it; a static sealing ring 21, the bottom of which is connected to the bottom plate 131 of the housing; the dynamic sealing ring 20 extends downward, and the static sealing ring 21 extends upward, and the overlapping positions of the dynamic sealing ring 20 and the static sealing ring 21 form an annular area P which is larger at the top and smaller at the bottom, and the third annular gap C is located below the annular area P, and the annular area P is connected to the sealing chamber M; a carbon ring body 22, which is fixed to the bottom of the static sealing ring 21 through a carbon ring pressure plate 23, and the carbon ring body 22 is radially close to the transmission disk 10 to form a contact seal; a sealing air duct 24, and the bottom of the static sealing ring 21 is connected with a sealing air duct 24, and the sealing air duct 24 is connected to the sealing chamber M.

[0041] The above scheme has an additional annular area with a larger top and a smaller bottom in the sealed chamber. When the pressure fluctuation in the primary air chamber causes the hot primary air to carry coal powder into the sealed chamber at a certain moment in a local part of the third annular gap, for the original machine base sealing structure, the coal powder carried into the sealed chamber by the hot primary air is deposited in the sealed chamber. For the machine base sealing device provided by the utility model, the coal powder carried into the sealed chamber by the hot primary air is deposited in the annular area with a larger top and a smaller bottom. When the pressure of the sealed chamber at this position is higher than the pressure of the primary air chamber at the next moment, the coal powder deposited in the annular area with a larger top and a smaller bottom is blown back into the primary air chamber.

[0042] The term "overlapping" in the present invention refers to the overlapping state of the shapes of two components in a spatial sense. The shape can be understood as the specific shape of the component, or the shape change of the component during use, and should not be understood as the two components being tightly fitted.

[0043] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0044] See attached Figure 5 In the embodiment of the utility model, the dynamic sealing ring 20 is sequentially connected with a first circular segment 201, a first conical segment 202 and a first cylindrical segment 203 from top to bottom. The top of the first circular segment 201 forms a plane and is rigidly connected to the transmission disc 10 and rotates with the transmission disc 10.

[0045] Specifically, the first annular segment 201 extends inwardly relative to the first conical segment 202 to form a plane, and the first conical segment 202 gradually extends outwardly relative to the first cylindrical segment 203 to form a first taper.

[0046] The included angle Y between the first conical segment 202 and the first cylindrical segment 203 is 150°-180°.

[0047] See attached Figure 6 In a specific embodiment of the utility model, the static sealing ring 21 is sequentially connected with a second conical segment 211, a second cylindrical segment 212 and a second annular segment 213 from top to bottom. The second conical segment 211 has a taper direction opposite to that of the first conical segment 202 and forms a V-shaped annular area P. A third annular gap C is formed between the first cylindrical segment 203 and the second cylindrical segment 212. The second annular segment 213 is rigidly connected to the housing bottom plate 131. The carbon ring body 22 is fixed on the second annular segment 213. The sealing air duct 24 is connected to the bottom of the second annular segment 213.

[0048] In the present utility model, unless otherwise clearly stipulated and limited, the terms such as "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.

[0049] The "rigid connection" in the present invention is also called a rigid connection. In this connection, the connected components can neither move nor rotate relative to each other at the connection. This connection is usually achieved by mechanical methods such as welding and bolting, so that the structure has a higher load-bearing capacity and stability.

[0050] Specifically, the second conical segment 211 gradually forms a second taper inwardly relative to the second cylindrical segment 212 , and the second annular segment 213 extends inwardly relative to the second cylindrical segment 212 to form an annular plane.

[0051] The included angle X between the second conical segment 211 and the second cylindrical segment 212 is 145°-150°.

[0052] In the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0053] See attached Figure 7 , the width T of the third annular gap C is 2-5 mm.

[0054] In the embodiment of the present invention, the horizontal distance S of the V-shaped annular area P increases with the increase of height.

[0055] By comparing T and S, it can be seen that the flow cross-sectional area of ​​the third annular gap C is much lower than the flow cross-sectional area in the V-shaped annular area. That is, the flow cross-sectional area of ​​the annular area P is larger than the flow cross-sectional area of ​​the third annular gap C.

[0056] At a certain moment, when the pressure of the sealed chamber at a certain position of the third annular gap C is lower than the pressure of the primary air chamber, the hot primary air carries the coal powder from this position into the third annular gap C. Assuming the flow rate is V1, when the hot primary air enters the V-shaped annular area, the flow rate of the hot primary air will be inversely proportional to the flow cross-sectional area and rapidly decrease to V2 due to the rapid increase in the cross-sectional area. The rapid decrease in the flow rate of the hot primary air will bring the following two effects: The first effect is that the ability of the hot primary air to carry coal powder is positively correlated with the flow rate. The faster the flow rate, the stronger the carrying capacity. Therefore, after the coal powder carried by the hot primary air in the third annular gap C enters the V-shaped annular area, the large particles of coal powder begin to settle and no longer continue to move with the airflow. The second effect is that due to the rapid decrease in flow rate, the movement speed of the fine coal powder that still flows with the hot primary air slows down. When these fine coal powders have not yet crossed the second conical section of the static sealing ring, the pressure of the sealed chamber here begins to be higher than the pressure of the primary air chamber. The sealing wind suppresses the hot primary air, and the airflow carries the fine coal powder and begins to flow to the primary air chamber. The sealing structure of the utility model significantly reduces the amount of coal powder entering the sealing chamber, reduces the wear between the carbon ring and the transmission disc, and increases the service life of the machine base seal.

[0057] The above technical scheme of the utility model avoids the coal powder in the primary air chamber from entering the sealing chamber without increasing the sealing air pressure, fundamentally solves the wear problem of the carbon ring of the existing machine base sealing structure, thereby ensuring that the machine base seal is in an effective sealing state for a long time. It is of great significance to solve the current problems of short machine base seal life and great difficulty in overhaul and maintenance of medium-speed coal mills, and has broad application prospects.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0059] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A medium speed mill seat sealing device, characterized in that: include: A dynamic sealing ring (20), the top of which is connected to the transmission plate (10) and moves with it; a static sealing ring (21), the bottom of the static sealing ring (21) being connected to the bottom plate (131) of the housing; the dynamic sealing ring (20) extending downward, the static sealing ring (21) extending upward, the overlapping position of the dynamic sealing ring (20) and the static sealing ring (21) forming an annular area (P) with a larger top and a smaller bottom, a third annular gap (C) being located below the annular area (P), and the annular area (P) being in communication with the sealing chamber (M); A carbon ring body (22), wherein the carbon ring body (22) is fixed to the bottom of the static sealing ring (21) via a carbon ring pressure plate (23), and the carbon ring body (22) and the transmission plate (10) are radially close to form a contact seal; A sealed air duct (24), wherein the bottom of the static sealing ring (21) is connected to a sealed air duct (24), and the sealed air duct (24) is in communication with the sealed chamber (M).

2. A medium speed mill seat sealing device according to claim 1, characterized in that: The dynamic sealing ring (20) is connected with a first annular segment (201), a first conical segment (202) and a first cylindrical segment (203) in sequence from top to bottom; the top of the first annular segment (201) forms a plane and is rigidly connected to the transmission disc (10) and rotates with the transmission disc (10).

3. A medium speed mill seat sealing device according to claim 2, characterized in that: The first annular segment (201) extends inwardly relative to the first conical segment (202) to form a plane, and the first conical segment (202) gradually extends outwardly relative to the first cylindrical segment (203) to form a first taper.

4. A medium speed mill seat sealing device according to claim 2, characterized in that: The included angle Y between the first conical section (202) and the first cylindrical section (203) is 150°-180°.

5. A medium speed mill seat sealing device according to claim 2, characterized in that: The static sealing ring (21) is connected with a second conical section (211), a second cylindrical section (212) and a second annular section (213) in sequence from top to bottom; the second conical section (211) has a taper direction opposite to that of the first conical section (202) and forms a V-shaped annular area (P); a third annular gap (C) is formed between the first cylindrical section (203) and the second cylindrical section (212); the second annular section (213) is rigidly connected to the bottom plate (131) of the housing; the carbon ring body (22) is fixed on the second annular section (213); and the sealing air duct (24) is connected to the bottom of the second annular section (213).

6. A medium speed mill seat sealing device according to claim 5, characterized in that: The second conical section (211) gradually forms a second taper inwardly relative to the second cylindrical section (212), and the second annular section (213) extends inwardly relative to the second cylindrical section (212) to form an annular plane.

7. A medium speed mill seat sealing device according to claim 5, characterized in that: An included angle X between the second conical section (211) and the second cylindrical section (212) is 145°-150°.

8. A medium speed mill stand sealing device according to any one of claims 1 to 7, characterized in that: The width T of the third annular gap (C) is 2-5 mm.

9. A medium speed mill seat sealing device according to claim 5, characterized in that: The horizontal distance S of the V-shaped annular area (P) increases with increasing height.

10. A medium speed mill seat sealing device according to claim 9, characterized in that: The flow cross-sectional area of ​​the annular region (P) is greater than the flow cross-sectional area of ​​the third annular gap (C).

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