A seal for a steam turbine

Abstract

This invention relates to a sealing device for a steam turbine, which is disposed at the end of a bearing housing and fitted onto the turbine rotor. The sealing device has a bearing side near the bearing and an air side on the other side. The sealing device includes an upper sealing assembly and a lower sealing assembly. The arc-shaped inner edges of the upper sealing assembly and the lower sealing assembly together form a rotor through hole, and the rotor is located in the rotor through hole. Airtight channels are respectively provided inside the upper sealing assembly and the lower sealing assembly. The airtight channels include a main vent hole, a group of auxiliary vent holes, and an air chamber. The main vent hole extends from the outer edge of the upper or lower sealing assembly into the air chamber. The group of auxiliary vent holes includes several auxiliary vent holes, which extend from the arc-shaped inner edge of the upper or lower sealing assembly into the air chamber.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, and more specifically to a sealing device for a steam turbine. Background Technology

[0002] A steam turbine is an external combustion rotary machine that converts the thermal energy of steam into mechanical work. The area where the turbine rotor mates with the oil baffle ring is a sealed chamber with small inlet and outlet. When the bearing housings on both sides of the turbine rotor are under negative pressure, impurities such as insulation cotton lint and inorganic dust from the working environment are easily drawn into the oil baffle ring of the bearing housing. At the same time, when the turbine is working, the impurities continuously drawn in mix with the lubricating oil and accumulate in the gap between the oil baffle teeth and the turbine rotor. Under the influence of high temperatures such as shaft seals, carbonization occurs. The carbonized material has high hardness and is prone to dynamic and static rubbing failures, which causes nonlinear vibration of the turbine rotor system. In particular, the bearings may exhibit random and irregular sudden jumping phenomena, which may even cause the turbine to trip, seriously affecting the operating stability and safety of the turbine. Summary of the Invention

[0003] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a sealing device for a steam turbine, which effectively prevents the steam turbine from sucking in external impurities during operation and prevents carbon buildup in the bearing positions of the steam turbine.

[0004] To achieve the above objectives, the present invention provides a sealing device for a steam turbine, which is disposed at the end of a bearing housing and fitted onto the rotor of the steam turbine. The side of the sealing device closest to the bearing is the bearing side, and the other side is the air side. The sealing device includes an upper sealing assembly and a lower sealing assembly. The arc-shaped inner edges of the upper sealing assembly and the lower sealing assembly together form a rotor through hole, and the rotor is located in the rotor through hole. Airtight channels are respectively provided inside the upper sealing assembly and the lower sealing assembly. The airtight channels include a main vent hole, a group of auxiliary vent holes, and an air chamber. The main vent hole extends from the outer edge of the upper sealing assembly or the lower sealing assembly into the air chamber. The group of auxiliary vent holes includes a plurality of auxiliary vent holes, which extend from the arc-shaped inner edge of the upper sealing assembly or the lower sealing assembly into the air chamber.

[0005] Furthermore, multiple oil seal plate groups are provided on the arc-shaped inner edge of the upper sealing assembly and the arc-shaped inner edge of the lower sealing assembly, and the multiple oil seal plate groups are arranged at intervals along the circumferential direction of the arc-shaped inner edge.

[0006] Furthermore, the oil seal assembly includes multiple oil seals, all of which are axially spaced along the inner edge of the arc, and all oil seals are flush at the end closest to the rotor.

[0007] Furthermore, both the inner arc-shaped edge of the upper sealing assembly and the inner arc-shaped edge of the lower sealing assembly are provided with stepped structures, the stepped structures including several stepped surfaces, and the diameter of the rotor through hole decreases in a stepped manner from the bearing side to the air side.

[0008] Furthermore, grooves are provided on the arc-shaped inner edge of the upper sealing component and the arc-shaped inner edge of the lower sealing component, and the oil seal is fixedly installed in the grooves by a press-riveting process.

[0009] Furthermore, an oil return groove is provided on the arc-shaped inner edge of the lower sealing assembly, and the oil return groove extends from the air side to the bearing side along the axial direction of the rotor.

[0010] Furthermore, the airtight channel is provided with multiple main vent holes and multiple secondary vent hole groups.

[0011] Furthermore, the air chamber is configured as an arc shape, and the air chamber is coaxially arranged with the rotor through hole.

[0012] Furthermore, the secondary vent group includes two secondary vents, the axes of which are located on both sides of the axis of the main vent along the axial direction of the inner edge of the arc, and the axes of the two secondary vents form angles α1 and α2 with the axis of the main vent, respectively, where 5°≤α1≤13° and 5°≤α2≤13°.

[0013] Furthermore, both the upper sealing assembly and the lower sealing assembly have air grooves on their air sides, and a sealing plate is provided on the opening of the air groove. An air chamber is formed between the air groove and the sealing plate.

[0014] As described above, the turbine sealing device of the present invention has the following beneficial effects:

[0015] 1. By setting airtight channels in the upper and lower sealing components respectively, when a micro-vacuum is established in the bearing housing, positive pressure can be formed in the rotor through hole, thereby preventing impurities from entering the bearing side of the sealing device and entering the bearing housing. This prevents impurities in the environment from being sucked into the bearing housing and avoids carbon buildup in the turbine bearing position. Correspondingly, it also prevents vibration problems caused by carbon buildup during turbine operation.

[0016] 2. By setting two secondary vents in the secondary vent group, it is possible to form a vortex in the airflow within the two secondary vents. The vortex can effectively prevent particulate impurities from entering the air chamber, ensuring the cleanliness of the air chamber and cleaning impurities within the air chamber. At the same time, the vortex can also effectively prevent the mixing of particulate impurities and lubricating oil, further avoiding carbon buildup at the turbine bearing positions, and effectively preventing the intake of water vapor, thus ensuring the quality of the lubricating oil. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the sealing device in this invention.

[0018] Figure 2 This is a schematic diagram of the main vent and air chamber in this invention.

[0019] Figure 3 This is a schematic diagram of the upper sealing assembly in this invention.

[0020] Figure 4 This is a schematic diagram of the lower sealing assembly in this invention.

[0021] Explanation of icon numbers

[0022] 1. Upper sealing assembly, 2. Lower sealing assembly, 3. Rotor through hole, 4. Main vent hole, 5. Secondary vent hole, 6. Air chamber, 7. Stepped structure, 701. Stepped surface, 702. Groove, 8. Oil seal plate assembly, 801. Oil seal plate, 9. Oil groove, 10. Bearing side, 11. Air side. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] See Figures 1 to 4 This invention provides a sealing device for a steam turbine, which is disposed at the end of a bearing housing and fitted onto the turbine rotor. The sealing device has a bearing side 10 near the bearing and an air side 11 on the other side. The sealing device includes an upper sealing assembly 1 and a lower sealing assembly 2. The arc-shaped inner edges of the upper sealing assembly 1 and the lower sealing assembly 2 together form a rotor through hole 3, and the rotor is located in the rotor through hole 3. Both the upper sealing assembly 1 and the lower sealing assembly 2 have airtight channels inside. Each airtight channel includes a main vent 4, a secondary vent group, and an air chamber 6. The main vent 4 extends from the outer edge of the upper sealing assembly 1 or the lower sealing assembly 2 to the air chamber 6. Specifically, the main vent 4 inside the upper sealing assembly 1 extends from the outer edge of the upper sealing assembly 1 to the air chamber 6 of the upper sealing assembly 1. The airtight channel inside the lower sealing assembly 2... The main vent 4 extends from the outer edge of the lower sealing assembly 2 into the air chamber 6 of the lower sealing assembly 2. A pipe interface and a shut-off valve are provided at the end of the main vent 4 furthest from the air chamber 6. The pipe interface is used to introduce gas into the main vent 4, and the shut-off valve is used to control the gas flow. Preferably, the diameter of the main vent 4 is 13.5 mm. The secondary vent group includes several secondary vents 5. Each secondary vent 5 extends from the inner arc-shaped edge of the upper sealing assembly 1 or the lower sealing assembly 2 into the air chamber 6. Specifically, the secondary vents 5 inside the upper sealing assembly 1 extend from the inner arc-shaped edge of the upper sealing assembly 1 into the air chamber 6 of the upper sealing assembly 1, and the secondary vents 5 inside the lower sealing assembly 2 extend from the inner arc-shaped edge of the lower sealing assembly 2 into the air chamber 6 of the lower sealing assembly 2. Preferably, the diameter of the secondary vent 5 is 3 mm.

[0028] The basic working principle of the turbine sealing device involved in this invention is as follows: When the turbine is running, compressed air is introduced into the sealing device through the main vent 4. Under the action of internal pressure, the compressed air returns to its original volume in the air chamber 6, while the air originally inside the air chamber 6 is squeezed out. At the same time, the diameter of the auxiliary vent 5 is preferably smaller than the diameter of the main vent 4. According to the continuity equation, when the cross-section decreases, the flow velocity increases. Therefore, by setting the auxiliary vent 5, the gas in the air chamber 6 can flow out at high speed, thereby forming a positive pressure in the rotor through hole 3. When a micro-vacuum is established in the bearing housing, the positive pressure can prevent impurities from entering the bearing side 10 of the sealing device through the rotor through hole 3 and entering the bearing housing. This prevents impurities in the environment from being sucked into the bearing housing and avoids carbon buildup at the bearing position of the turbine. Correspondingly, it also prevents vibration problems caused by carbon buildup during turbine operation.

[0029] See Figures 1 to 4 The present invention will be further described below with reference to a specific embodiment:

[0030] In this embodiment, see Figure 3 and Figure 4 As a preferred design, multiple oil seal plate groups 8 are provided on the arc-shaped inner edge of the upper sealing component 1 and the arc-shaped inner edge of the lower sealing component 2. The multiple oil seal plate groups 8 are arranged at intervals along the circumference of the arc-shaped inner edge. The multiple oil seal plate groups 8 can collect lubricating oil that has not been thrown off the rotor by centrifugal force and leaked along the rotor from all directions of the rotor, thereby improving the efficiency of lubricating oil collection.

[0031] In this embodiment, see Figure 3 and Figure 4 As a preferred design, the oil seal assembly 8 includes multiple oil seals 801, and the multiple oil seals 801 are axially spaced along the inner edge of the arc. All oil seals 801 are flush at the end near the rotor, so that the distance between the end of the oil seal 801 near the rotor and the rotor is the same. When lubricating oil leaks out, the lubricating oil can flow along the oil seal 801, which facilitates the return of lubricating oil and improves the efficiency of lubricating oil return.

[0032] In this embodiment, see Figure 3 and Figure 4 As a preferred design, both the inner arc-shaped edges of the upper sealing assembly 1 and the lower sealing assembly 2 are provided with stepped structures 7 for the return of lubricating oil. The stepped structure 7 includes several stepped surfaces 701. The diameter of the rotor through-hole 3 decreases in a stepped manner from the bearing side 10 to the air side 11. Specifically, the lubricating oil on the stepped structure 7 in the upper sealing assembly 1 can flow along the wall from the stepped surface 701 with a larger radius to the stepped surface 701 with a smaller radius under the action of gravity at adjacent stepped surfaces 701. The stepped structure 7 of the lower sealing assembly 2 allows lubricating oil to flow from the bearing side 10 to the air side 11 along the stepped surface 701. Based on a similar principle, the stepped structure 7 of the lower sealing assembly 2 allows lubricating oil to flow from the air side 11 to the bearing side 10 along the stepped surface 701. On the one hand, the flow of lubricating oil along the stepped surface 701 can further improve the efficiency of lubricating oil return. On the other hand, the stepped structure 7 makes the lubricating oil on the upper side of the rotor and the lubricating oil on the lower side of the rotor flow in different directions, which can prevent the lubricating oil return from being blocked and not flowing smoothly.

[0033] In this embodiment, see Figure 3 and Figure 4 As a preferred design, the inner arc of the upper sealing component 1 and the inner arc of the lower sealing component 2 are also provided with grooves 702. The oil seal plate 801 is fixedly installed in the grooves 702 by a press-riveting process, which is easy to install, has high tensile strength, and can provide a durable connection under heavy load.

[0034] In this embodiment, see Figure 1As a preferred design, the lower sealing assembly 2 is provided with an oil return groove 9 on its arc-shaped inner edge, and the oil return groove 9 is preferably located at the bottom of the arc-shaped inner edge. The oil return groove 9 extends from the air side 11 to the bearing side 10 along the axial direction of the rotor, so as to facilitate the return of lubricating oil to the bearing housing.

[0035] In this embodiment, see Figure 1 As a preferred design, the airtight channel is provided with multiple main vent holes 4 and multiple secondary vent hole groups. Multiple main vent holes 4 can improve the efficiency of ventilation into the air chamber 6, and multiple secondary vent hole groups can cover the entire outer circumference of the rotor and improve the sealing performance. Among them, multiple secondary vent hole groups are arranged circumferentially along the inner edge of the arc. Preferably, the central angle between any two adjacent secondary vent hole groups inside the upper sealing component 1 and the center of the inner edge of the arc is 15°, and the central angle between any two adjacent secondary vent hole groups inside the lower sealing component 2 and the center of the inner edge of the arc is 15°, so that the airflow between the multiple secondary vent hole groups does not interfere with each other.

[0036] In this embodiment, see Figure 1 As a preferred design, the air chamber 6 is set in an arc shape, and the air chamber 6 is coaxially arranged with the rotor through hole 3, so that all the secondary vent holes 5 are at the same distance from the inner edge of the arc shape of the upper sealing assembly 1 or the lower sealing assembly 2 to the air chamber 6, which facilitates the setting of the secondary vent holes 5 and can improve the stability of the seal.

[0037] In this embodiment, see Figure 2 As a preferred design, the secondary vent assembly includes two secondary vents 5. The axes of the two secondary vents 5 are located on both sides of the axis of the main vent 4 along the axial direction of the inner edge of the arc. The axes of the two secondary vents (5) form angles α1 and α2 with the axis of the main vent (4), respectively, where 5°≤α1≤13° and 5°≤α2≤13°. The angles α1 and α2 facilitate the formation of vortices in the airflow within the two secondary vents 5. The inner edge of the upper sealing assembly 1 is located on the inner edge of the arc. A positive pressure gradient is formed at the arc-shaped inner edge of the lower sealing component 2, thereby forming a vortex in the air chamber 6. The vortex can effectively prevent particulate impurities from entering the air chamber 6, ensuring the cleanliness of the air chamber 6, and can also clean the impurities in the air chamber 6. At the same time, the vortex can also effectively block the mixing of particulate impurities and lubricating oil, further preventing carbon deposits in the turbine bearings, and effectively preventing the intake of water vapor, ensuring the quality of the lubricating oil.

[0038] In this embodiment, see Figure 1 and Figure 2As a preferred design, air grooves are provided on the air sides 11 of both the upper sealing component 1 and the lower sealing component 2. A sealing plate is provided on the opening of the air groove, and an air chamber 6 is formed between the air groove and the sealing plate. Preferably, the width of the air groove is 15mm, the depth is 30mm, and the thickness of the sealing plate is 5mm. The structure is simple and easy to process.

[0039] As described above, the turbine sealing device of the present invention has the following beneficial effects:

[0040] 1. By setting airtight channels in the upper sealing assembly 1 and the lower sealing assembly 2 respectively, when a micro-vacuum is established in the bearing housing, positive pressure can be formed in the rotor through hole 3, thereby preventing impurities from entering the bearing side 10 of the sealing device and entering the bearing housing. This prevents impurities in the environment from being sucked into the bearing housing and avoids carbon buildup in the turbine bearing position. Correspondingly, it also prevents vibration problems caused by carbon buildup during turbine operation.

[0041] 2. By setting two secondary vents 5 in the secondary vent group, the airflow can easily form a vortex in the two secondary vents 5. The vortex can effectively prevent particulate impurities from entering the air chamber 6, ensuring the cleanliness of the air chamber 6. It can also clean the impurities in the air chamber 6. At the same time, the vortex can also effectively prevent the mixing of particulate impurities and lubricating oil, further avoiding carbon buildup at the turbine bearing position, and effectively preventing the intake of water vapor, thus ensuring the quality of the lubricating oil.

[0042] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A sealing device for a steam turbine, disposed at the end of a bearing housing and fitted onto the rotor of the steam turbine, wherein the sealing device has a bearing side (10) near the bearing and an air side (11) on the other side, characterized in that: The sealing device includes an upper sealing component (1) and a lower sealing component (2). The arc-shaped inner edge of the upper sealing component (1) and the arc-shaped inner edge of the lower sealing component (2) together form a rotor through hole (3), and the rotor is located in the rotor through hole (3). The upper sealing component (1) and the lower sealing component (2) are respectively provided with airtight channels. The airtight channels include a main vent (4), a group of auxiliary vents and an air chamber (6). The main vent (4) penetrates from the outer edge of the upper sealing component (1) or the lower sealing component (2) to the air chamber (6). The group of auxiliary vents includes a number of auxiliary vents (5). The auxiliary vents (5) penetrate from the arc-shaped inner edge of the upper sealing component (1) or the lower sealing component (2) to the air chamber (6).

2. The sealing device for a steam turbine according to claim 1, characterized in that: Multiple oil seal plate groups (8) are provided on the arc-shaped inner edge of the upper sealing component (1) and the arc-shaped inner edge of the lower sealing component (2), and the multiple oil seal plate groups (8) are arranged at intervals along the circumference of the arc-shaped inner edge.

3. The sealing device for a steam turbine according to claim 2, characterized in that: The oil seal assembly (8) includes multiple oil seals (801), and the multiple oil seals (801) are axially spaced along the inner edge of the arc, and all oil seals (801) are flush at the end near the rotor.

4. The sealing device for a steam turbine according to claim 1 or 3, characterized in that: Both the inner arc of the upper sealing assembly (1) and the inner arc of the lower sealing assembly (2) are provided with stepped structures (7). The stepped structures (7) include several stepped surfaces (701). The diameter of the rotor through hole (3) decreases in a stepped manner from the bearing side (10) to the air side (11).

5. The sealing device for a steam turbine according to claim 3, characterized in that: The upper sealing assembly (1) and the lower sealing assembly (2) are provided with grooves (702) on their arc-shaped inner edges, and the oil seal (801) is fixedly installed in the grooves (702) by a riveting process.

6. The sealing device for a steam turbine according to claim 1, characterized in that: The lower sealing assembly (2) has an oil return groove (9) on its arc-shaped inner edge, which extends from the air side (11) to the bearing side (10) along the axial direction of the rotor.

7. The sealing device for a steam turbine according to claim 1, characterized in that: The airtight channel is provided with multiple main vents (4) and secondary vents.

8. The sealing device for a steam turbine according to claim 1, characterized in that: The air chamber (6) is configured as an arc shape, and the air chamber (6) is coaxially arranged with the rotor through hole (3).

9. The sealing device for a steam turbine according to claim 1, characterized in that: The auxiliary vent group includes two auxiliary vents (5). The axes of the two auxiliary vents (5) are located on both sides of the axis of the main vent (4) along the axial direction of the inner edge of the arc. The axes of the two auxiliary vents (5) form angles α1 and α2 with the axis of the main vent (4), respectively, where 5°≤α1≤13° and 5°≤α2≤13°.

10. The sealing device for a steam turbine according to claim 1, characterized in that: Both the upper sealing assembly (1) and the lower sealing assembly (2) have air grooves on their air sides (11), and a sealing plate is provided on the opening of the air groove. An air chamber (6) is formed between the air groove and the sealing plate.

Images