Inflation sealing type stationary blade bearing for axial flow turbine unit and sealing method

Abstract

The invention relates to the technical field of large turbine machinery, and provides an inflatable sealing type stationary blade bearing for an axial flow turbine unit, which comprises a bearing body, the bearing body is of a cylindrical structure, a cavity penetrating along the axial direction and a rotating shaft used for mounting and supporting a stationary blade are arranged in the bearing body, one end of the bearing body is provided with a flange sealing surface connected with a unit bearing cylinder body, and the other end of the bearing body is provided with a flange. An air inlet threaded hole channel is formed in the flange sealing surface and is used for introducing sealing air into an internal air path arranged in the bearing body; the internal air channel comprises an axial hole channel communicated with the air inlet threaded hole channel, a radial hole channel communicated with the end, away from the air inlet, of the axial hole channel, an annular pressure equalizing groove formed in the outer wall of the bearing body and communicated with the radial hole channel and a plurality of air guide hole channels communicated with the annular pressure equalizing groove and the cavity, and the air guide hole channels are evenly arranged in the circumferential direction; a top bearing and a bottom bearing are respectively arranged at two ends of the cavity. The problem that in the prior art, a system is forced to stop due to the fact that static blades of a unit are prone to being jammed due to running environment damage is solved.

Description

Technical Field

[0001] This invention relates to the field of large-scale turbine machinery technology, and in particular to an air-filled sealed stationary blade bearing and sealing method for axial flow turbine units. Background Technology

[0002] Large industrial axial flow turbine units (such as axial flow compressors and blowers) are key core equipment in petrochemical, coal chemical, and metallurgical industries. The continuity and stability of their operation directly affect the safety and economic benefits of the entire production plant. To adapt to complex process conditions, modern large axial flow units generally adopt adjustable stationary blade technology, which optimizes unit efficiency and regulates gas flow by changing the installation angle of the stationary blades in real time.

[0003] In the adjustable vane mechanism, the vane bearing is the core component for achieving the adjustment function. It is fixedly installed on the vane bearing body or housing of the unit, and the vane shaft is assembled in the inner hole of the bearing. The vane bearing plays the roles of support and lubrication, rotation center, and interface sealing. At the same time, the vane rotates under the drive ring and the crank at the tail of the vane, thereby adjusting the vane angle and thus achieving the purpose of regulating the gas flow.

[0004] Currently, graphite sleeves are commonly used for lubrication and sealing at both ends of the stator bearing. Graphite material has certain self-lubricating and high-temperature resistance properties, which are acceptable in short-term clean operating conditions. However, in actual industrial operating environments, the compressed process gas often contains dust, catalyst particles, moisture, condensate oil, and even corrosive media such as hydrogen sulfide. Because graphite is relatively soft, wear is inevitable between it and the stator blade during long-term operation, leading to a gradual increase in the clearance. This increased clearance provides a channel for impurities and condensate in the gas. These contaminants can penetrate the tiny gaps between the bearing and the stator blade, mix with the graphite powder produced by wear, gradually harden, and form a stubborn fouling layer. Ultimately, this leads to a sharp increase in the stator blade's rotational resistance until it becomes completely jammed and unable to rotate. Once the stator blade jams, it can cause problems such as the inability to adjust the stator blade angle, shearing of the crank pin, and breakage of the pistol plate. The unit's adjustable stator blade function will completely fail, affecting process operation, forcing the entire system to shut down for maintenance, and resulting in huge economic losses. Summary of the Invention

[0005] This invention provides an air-filled sealed stator bearing and sealing method for axial flow turbine units, to solve the problem in the prior art where the stator blades are easily jammed due to damage from the operating environment, leading to forced system shutdown.

[0006] This invention is achieved through the following technical solution: providing a gas-filled sealed stator bearing for an axial flow turbine unit, comprising a bearing body mounted on the unit's bearing cylinder. The bearing body is a cylindrical structure with an axially penetrating cavity inside for mounting and supporting the stator shaft. One end of the bearing body has a flange sealing surface connected to the unit's bearing cylinder. The flange sealing surface has an inlet threaded channel for introducing sealing gas into an internal air passage within the bearing body. The internal air passage includes an axial channel communicating with the inlet threaded channel, a radial channel communicating with the axial channel away from the inlet end, an annular pressure equalizing groove disposed on the outer wall of the bearing body and communicating with the radial channel, and multiple air guide channels connecting the annular pressure equalizing groove and the cavity. The air guide channels are evenly arranged along the circumference. A top bearing and a bottom bearing are respectively disposed at both ends of the cavity.

[0007] Specifically, the top bearing is located at one end near the axial passage, and the top bearing also includes a positioning flange, which is fixed to the end of the top bearing and closes the port of the axial passage near the flange sealing surface; the working surfaces of the top bearing and the bottom bearing are provided with a self-lubricating structure.

[0008] Specifically, the cavity includes, in sequence along the axial direction, a first cavity segment, a second cavity segment, and a third cavity segment arranged coaxially, wherein the diameter of the second cavity segment is smaller than that of the first cavity segment and the third cavity segment; the top bearing is installed in the first cavity segment, and the bottom bearing is installed in the third cavity segment.

[0009] Specifically, the first cavity segment and the third cavity segment are each provided with a 1° chamfer inward.

[0010] Specifically, a polytetrafluoroethylene (PTFE) sealing ring is provided between the bottom bearing and the cavity wall of the third cavity section.

[0011] Specifically, four air guide channels are provided.

[0012] Specifically, the bearing body has an annular groove on the outer wall of the end where the bottom bearing is located, and the annular groove is used to install a sealing ring.

[0013] Specifically, the flange sealing surface is provided with two connecting bolt holes.

[0014] A sealing method for a gas-filled sealed type stationary vane bearing in an axial flow turbine unit, comprising the following steps:

[0015] S1, The stationary vane bearing is installed and fixed to the unit bearing cylinder body, and the stationary vane shaft passes through the cavity of the bearing body;

[0016] S2, introduce sealing gas into the air inlet threaded passage;

[0017] S3, the sealing gas flows sequentially through the axial channel and the radial channel into the annular pressure equalization groove;

[0018] S4, after the sealing gas is pressurized in the annular pressure equalization groove, it flows evenly through the multiple air guide channels to the gap between the stationary blade shaft and the inner wall of the bearing body to form an annular air curtain;

[0019] S5, maintain the pressure of the sealing gas so that it remains higher than the medium pressure of the environment in which the stationary blade bearing is located.

[0020] Specifically, the step of maintaining the sealing gas pressure in S5 is as follows:

[0021] S51 provides a high-pressure inflation branch before the pneumatic control valve and a low-pressure inflation branch after the valve.

[0022] S52, select either the high-pressure inflation branch or the low-pressure inflation branch as the air source based on the real-time value of the medium pressure.

[0023] S53, adjust the pressure of the gas source to make it stably 20 kPa to 30 kPa higher than the pressure of the medium.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] A sealed gas channel is constructed by using axial, radial, and circumferentially distributed air guide channels within the bearing housing to directly reach the bearing's working clearance from an external air source. A slightly positive pressure sealing gas is actively introduced and maintained. This sealing gas is introduced into the threaded channels, then enters the axial channels, flows out from the radial channels into the annular pressure equalization groove, accumulates, and flows back into the air guide channels. It then enters the gap between the stator shaft and the bearing housing cavity, forming an air-filled seal. This creates a uniform and stable annular air curtain barrier around the stator shaft. Finally, the sealing gas flows out axially from the gap between the bearing housing and the stator shaft. This barrier continuously prevents the intrusion of dust, droplets, and other impurities, ensuring that the unit will not be forced to shut down due to stator jamming, greatly improving the unit's operational safety and stability, and reducing the frequency of unexpected shutdowns. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the connection structure of the pneumatically sealed stationary blade bearing used in an axial flow turbine unit according to the present invention;

[0027] Figure 2 This is a schematic cross-sectional view of the pneumatically sealed stator bearing used in an axial-flow turbine unit according to the present invention. Figure 1 ;

[0028] Figure 3This is a schematic cross-sectional view of the pneumatically sealed stator bearing used in an axial-flow turbine unit according to the present invention. Figure 2 ;

[0029] Figure 4 This is a top view of the pneumatically sealed stator bearing for axial flow turbine units according to the present invention. Figure 1 ;

[0030] Figure 5 This is a top view of the pneumatically sealed stator bearing for axial flow turbine units according to the present invention. Figure 2 ;

[0031] Figure 6 This is a schematic diagram of the top bearing structure of the pneumatically sealed stationary vane bearing used in an axial flow turbine unit according to the present invention.

[0032] Figure 7 This is a top view of the top bearing structure of the pneumatically sealed stationary blade bearing for an axial flow turbine unit according to the present invention.

[0033] Figure 8 This is a schematic diagram of the bottom bearing cross-section structure of the pneumatically sealed stationary vane bearing used in an axial flow turbine unit according to the present invention.

[0034] Figure 9 This is a bottom view of the bottom bearing structure of the pneumatically sealed stationary vane bearing of the present invention for an axial flow turbine unit.

[0035] Figure 10 This is a schematic diagram of the polytetrafluoroethylene (PTFE) sealing ring structure for the gas-filled sealed stator vane bearing of an axial flow turbine unit according to the present invention. Figure 1 ;

[0036] Figure 11 This is a schematic diagram of the polytetrafluoroethylene (PTFE) sealing ring structure for the gas-filled sealed stator vane bearing of an axial flow turbine unit according to the present invention. Figure 2 ;

[0037] Figure 12 This is a schematic diagram of the installation cross-sectional structure of the pneumatically sealed stator bearing used in an axial flow turbine unit according to the present invention.

[0038] Figure 13 This is a schematic diagram of the nitrogen gas sealing main pipe for the gas-filled sealed stationary blade bearing of the present invention used in axial flow turbine units.

[0039] In the attached diagram: 1. Bearing body; 11. Connecting bolt hole; 12. First cavity section; 121. First chamfer; 13. Third cavity section; 131. Second chamfer; 14. Axial channel; 15. Inlet threaded channel; 16. Radial channel; 17. Air guide channel; 18. Annular groove; 19. Annular pressure equalizing groove; 2. Top bearing; 21. Top bearing body; 22. Top graphite column; 211. Positioning flange; 3. Bottom bearing; 31. Bottom bearing body; 32. Bottom graphite column; 4. Sealing ring; 5. PTFE sealing ring; 6. Joint; 7. Pipe; 71. T-joint; 72. Pipe joint; 73. Pipe clamp; 8. Unit bearing cylinder body. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0042] Please see Figures 1-13 The present invention provides an air-sealed stationary blade bearing for an axial flow turbine unit, comprising a bearing body 1, a top bearing 2 and a bottom bearing 3;

[0043] The bearing housing 1 is mounted on the unit bearing cylinder 8 of the axial flow turbine unit. The bearing housing 1 has a cylindrical structure with an axially extending cavity inside. The cavity is used to install and support the rotating shaft of the stator vanes. One end of the bearing housing 1 has a flange sealing surface that connects to the unit bearing cylinder 8. The flange sealing surface has an air inlet threaded channel 15 for connecting to an external air inlet pipe connector 72. The air inlet threaded channel 15 is used to introduce sealing gas into the internal air passage provided inside the bearing housing 1. Figure 4 As shown, a connector 6 is provided on the air intake threaded channel 15, and the connector 6 is matched with the pipe connector 72.

[0044] The internal air passage includes an axial passage 14 connected to the inlet threaded passage 15, a radial passage 16 connected to the axial passage 14 away from the inlet end, an annular pressure equalizing groove 19 disposed on the outer wall of the bearing body 1 and connected to the radial passage 16, and a plurality of air guide passages 17 connecting the annular pressure equalizing groove 19 and the cavity. The air guide passages 17 are evenly arranged along the circumference to ensure the sealing effect.

[0045] The top bearing 2 and the bottom bearing 3 are respectively located at both ends of the cavity.

[0046] This device, through the sequential connection and spatial communication of an inlet threaded channel 15, an axial channel 14, a radial channel 16, an annular pressure equalizing groove 19, and multiple air guide channels 17, collaboratively forms a sealed, integrated internal gas channel. By introducing sealing gas into the threaded channel 15, the sealing gas enters the axial channel 14. The sealing gas flows from the inlet threaded channel 15, sequentially through the axial channel 14 and the radial channel 16, and then into the annular pressure equalizing groove 19 machined on the outer wall of the bearing body 1. After being buffered and pressure-equalized within the annular pressure equalizing groove 19, the gas flows out through the multiple circumferentially distributed air guide channels 17, entering the annular gap between the stator shaft and the inner wall of the bearing body 1, thus forming a uniformly inflated sealing gas curtain surrounding the shaft. Finally, the sealing gas flows out axially through the annular gap. This design greatly prevents media leakage and the entry of impurities and dirt from the media into the stator bearing, thus avoiding stator bearing jamming.

[0047] In an optional embodiment, the top bearing 2 is disposed at one end near the axial passage 14. The top bearing 2 also includes a positioning flange 211, which is fixed to the end of the top bearing 2 and closes the port of the axial passage 14 near the flange sealing surface. The working surfaces of the top bearing 2 and the bottom bearing 3 are provided with a self-lubricating structure.

[0048] In an optional embodiment, the top bearing 2 and the bottom bearing 3 are mounted on the inner wall of the bearing body 1 with a slight interference fit to form a stator bearing. After the top bearing 2 is installed, the end face of the left positioning flange 211 closes the port of the axial channel 14.

[0049] like Figure 3 As shown, a certain distance is left between the air guide channel 17 and the radial channel 16 and the axial channel 14, and the radial channel 16 connects to the end of the axial channel 14. Figure 2 and Figure 3As shown, the top bearing 2 is located at one end near the axial channel 14. The top bearing 2 includes a cylindrical top bearing body 21, multiple top graphite pillars 22, and a positioning flange 211. The multiple top graphite pillars 22 are circumferentially embedded in the side wall of the top bearing body 21. The positioning flange 211 is located at the end of the top bearing body 21. The port of the axial channel 14 is closed by the end face of the positioning flange 211, reducing material consumption. In other embodiments, threads can be machined at the port to screw in plugs or weld them in. The bottom bearing 3 includes a cylindrical bottom bearing body 31 and multiple bottom graphite pillars 32. The multiple bottom graphite pillars 32 are respectively embedded in the side wall and circumferential end face of the bottom bearing body 31.

[0050] In an optional embodiment, such as Figure 6 and Figure 7 As shown, the top bearing body 21 can be made of high-strength brass, which has strong wear resistance, high strength, high hardness, and chemical corrosion resistance. Two rings of top graphite pillars 22 are embedded on the end face of the positioning flange 211. These graphite pillars provide excellent lubrication to the bearing body 1. Figure 8 and Figure 9 As shown, a ring of bottom graphite pillars 32 is provided on the circumferential end face of the bottom bearing body 31.

[0051] In an optional embodiment, such as Figure 3 As shown, the cavity includes a first cavity section 12, a second cavity section, and a third cavity section 13 arranged coaxially along the axial direction. The diameter of the second cavity section is smaller than that of the first cavity section 12 and the third cavity section 13. The top bearing 2 is installed in the first cavity section 12, and the bottom bearing 3 is installed in the third cavity section 13.

[0052] In an optional embodiment, the first cavity 12 and the third cavity 13 are respectively provided with a 1° chamfer inward. The chamfer provided in the first cavity 12 is a first chamfer 121, and the chamfer provided in the third cavity 13 is a second chamfer 131, which facilitates the installation of the top bearing 2 and the bottom bearing 3.

[0053] In an optional embodiment, a space is provided between the bottom bearing 3 and the cavity wall of the third cavity 13 as shown in the figure. Figure 10 and Figure 11 The polytetrafluoroethylene sealing ring 5 shown forms a seal.

[0054] In an optional embodiment, four air guide channels 17 are provided, which are radially arranged around the bearing body 1 to ensure smooth and reliable sealing airflow.

[0055] In an optional embodiment, the bearing body 1 has an annular groove 18 on the outer wall of the end where the bottom bearing 3 is provided. The annular groove 18 is used to install the sealing ring 4 to ensure that a sealing cavity is formed between the outer side of the stationary blade bearing and the mounting hole of the bearing body 1 after the stationary blade bearing is installed. This cavity is used for gas buffering and ensures that the sealing gas in the sealing cavity can flow evenly through the air guide channels 17 that are evenly arranged along the circumference of the bearing body 1.

[0056] In an optional embodiment, such as Figure 5 As shown, there are two connecting bolt holes 11 on the left and right sides on the flange sealing surface. The inner diameter of the right connecting bolt hole 11 is smaller than the outer diameter of the side wall of the bearing body 1. The side wall of the bearing body 1 serves as the surface that mates with the unit's cylinder body 8 after installation.

[0057] A sealing method for a gas-filled sealed type stationary vane bearing in an axial flow turbine unit, comprising the following steps:

[0058] S1: The stator bearing is installed and fixed to the unit bearing cylinder 8 through its flange sealing surface and connecting bolt hole 11, and the stator shaft is inserted into the cavity of the bearing body 1 and supported by the top bearing 2 and the bottom bearing 3.

[0059] S2: Connect the external air inlet pipe connector 72 to the air inlet threaded hole 15 on the flange sealing surface, and introduce sealing gas into the air inlet threaded hole 15.

[0060] S3: As Figure 12 As shown, the sealing gas flows sequentially through the axial channel 14 and the radial channel 16, and then enters the annular equalizing groove 19.

[0061] S4: After the sealing gas is buffered and equalized in the annular pressure equalization groove 19, it flows evenly to the gap between the stationary blade shaft and the inner wall of the bearing body 1 through multiple air guide channels 17 evenly arranged along the circumference, forming an annular air curtain.

[0062] S5: Maintain the pressure of the sealing gas so that it remains higher than the pressure of the medium in the environment where the stator bearing is located.

[0063] The steps for maintaining the sealing gas pressure in S5 are as follows:

[0064] S51: Provides a high-pressure inflation branch before the pneumatic control valve and a low-pressure inflation branch after the valve.

[0065] S52: Select either the high-pressure or low-pressure inflation branch as the air source based on the real-time value of the medium pressure.

[0066] S53: Adjust the pressure of the air source to make it stably 20 kPa to 30 kPa higher than the medium pressure.

[0067] In an optional embodiment, such as Figure 1and Figure 13 As shown, the sealing gas is nitrogen. Two nitrogen charging pipelines are provided: one serves as the primary sealing gas source, taking pressure from before the pneumatic regulating valve (high-pressure charging branch); the other serves as the secondary sealing gas source, taking pressure from after the pneumatic regulating valve (low-pressure charging branch). Each branch is equipped with a manual shut-off valve (DN15 PN1.6MPa) and a pressure gauge. The sealing gas flows in through pipe 7, then through a tee fitting 71 to the pipe fitting 72 of the stator bearing, and is secured with pipe clamps 73. Before starting the axial flow turbine unit, the manual shut-off valves of both nitrogen charging pipeline branches are closed. After starting the axial flow turbine unit, the high-pressure or low-pressure nitrogen charging branch is selected based on the pressure value displayed on the pressure gauge, ensuring that the charging pressure is 20 kPa to 30 kPa higher than the medium pressure.

[0068] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. This application is not limited to the exact structures described above and illustrated in the accompanying drawings, and it should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, various changes and modifications made without departing from the concept of this application should be considered to fall within the protection scope of this application.

Claims

1. A gas-filled sealed stator bearing for an axial flow turbine unit, comprising a bearing body (1), said bearing body (1) being mounted on the unit bearing cylinder body (8) of the axial flow turbine unit, characterized in that, The bearing body (1) is a cylindrical structure with an axial cavity inside for installing and supporting the rotating shaft of the stator vane. One end of the bearing body (1) is provided with a flange sealing surface connected to the unit bearing cylinder body (8). An air inlet threaded channel (15) is provided on the flange sealing surface for introducing sealing gas into the internal air passage provided in the bearing body (1). The internal air passage includes an axial passage (14) communicating with the intake threaded passage (15), a radial passage (16) communicating with the axial passage (14) away from the intake end, an annular pressure equalizing groove (19) disposed on the outer wall of the bearing body (1) and communicating with the radial passage (16), and a plurality of air guide passages (17) communicating with the annular pressure equalizing groove (19) and the cavity, wherein the air guide passages (17) are uniformly arranged along the circumferential direction. The cavity is provided with a top bearing (2) and a bottom bearing (3) at both ends.

2. The gas-filled sealed stator bearing for axial flow turbine units according to claim 1, characterized in that, The top bearing (2) is located at one end near the axial passage (14). The top bearing (2) also includes a positioning flange (211), which is fixed to the end of the top bearing (2) and closes the port of the axial passage (14) near the flange sealing surface. The working surfaces of the top bearing (2) and the bottom bearing (3) are provided with self-lubricating structures.

3. The gas-filled sealed stator bearing for axial flow turbine units according to claim 1, characterized in that, The cavity includes, along the axial direction, a first cavity segment (12), a second cavity segment, and a third cavity segment (13) arranged coaxially, wherein the diameter of the second cavity segment is smaller than that of the first cavity segment (12) and the third cavity segment (13). The top bearing (2) is installed in the first cavity (12), and the bottom bearing (3) is installed in the third cavity (13).

4. The gas-filled sealed stator bearing for axial flow turbine units according to claim 3, characterized in that, The first cavity segment (12) and the third cavity segment (13) are respectively provided with a 1° chamfer inward.

5. The gas-filled sealed stationary blade bearing for axial flow turbine units according to claim 3, characterized in that, A polytetrafluoroethylene sealing ring (5) is provided between the bottom bearing (3) and the cavity wall of the third cavity (13).

6. The gas-filled sealed stator bearing for axial flow turbine units according to claim 1, characterized in that, The air guide channel (17) is provided with four.

7. The gas-filled sealed stator bearing for axial flow turbine units according to claim 1, characterized in that, The bearing body (1) has an annular groove (18) on the outer wall of the end where the bottom bearing (3) is located. The annular groove (18) is used to install the sealing ring (4).

8. The gas-filled sealed stator bearing for axial flow turbine units according to claim 1, characterized in that, Two bolt holes are provided on the flange sealing surface.

9. A sealing method for a pneumatically sealed stationary vane bearing in an axial-flow turbine unit, characterized in that, The method for use in the stator bearing according to any one of claims 1-8 includes the following steps. S1, the stationary blade bearing is installed and fixed to the unit bearing cylinder body (8), and the stationary blade shaft is inserted into the cavity of the bearing body (1); S2, introduce sealing gas into the inlet threaded passage (15); S3, the sealing gas flows sequentially through the axial channel (14) and the radial channel (16) into the annular equalizing groove (19). S4, after the sealing gas is pressurized in the annular equalizing groove (19), it flows evenly through the multiple air guide channels (17) to the gap between the stationary blade shaft and the inner wall of the bearing body (1) to form an annular air curtain; S5, maintain the pressure of the sealing gas so that it remains higher than the medium pressure of the environment in which the stationary blade bearing is located.

10. The sealing method for an air-filled sealed stationary blade bearing in an axial flow turbine unit according to claim 9, characterized in that, The step in S5 to maintain the sealing gas pressure is as follows: S51 provides a high-pressure charging branch before the pneumatic control valve and a low-pressure charging branch after the valve. S52, select either the high-pressure inflation branch or the low-pressure inflation branch as the gas source based on the real-time value of the medium pressure. S53, adjust the pressure of the gas source to make it stably 20 kPa to 30 kPa higher than the pressure of the medium.

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