A micro axial flow turbine sealing device

Abstract

The present invention relates to the field of rotary machine seals, and discloses a micro axial flow turbine sealing device disposed between a housing and a rotating shaft, including: a micro axial flow turbine and a multi-stage annular seal arranged axially. A stage interval is formed between any two adjacent annular seals, and at least one stage interval is provided with a micro axial flow turbine. The micro axial flow turbine includes a plurality of turbine blades arranged circumferentially along the rotating shaft, and each turbine blade is fixedly connected to the rotating shaft. Each turbine blade can expand and reduce the pressure of the leakage gas, and when the leakage gas flows along the axial direction of the rotating shaft, each turbine blade can deflect the flow direction of the leakage gas. By expanding and reducing the pressure of the leakage gas, the pressure of the leakage gas can be reduced. At the same time, by deflecting the flow direction of the leakage gas, the airflow flowing to the next-stage annular seal can be reduced, thereby improving the sealing effect. The cooperation of the micro axial flow turbine and the annular seal can shorten the axial distance.

Description

Technical Field

[0001] The present invention relates to the field of rotary machine seals, and particularly to a micro axial flow turbine seal device. Background Art

[0002] As a core component in industrial production, the sealing problem of rotary machines is one of the technical difficulties, especially when the leaked gas is toxic, flammable or explosive. As Figure 10 and Figure 11 shown, non-contact seals are generally used on rotary machines, such as annular seal seals. As the name implies, there is a certain gap between the rotating shaft and the annular seal in non-contact seals without contact. Where there is a gap, there must be leakage. To reduce the leakage amount, the most commonly used sealing method is to increase the number of stages of annular seals. The principle is that the leaked gas loses energy and reduces pressure in one stage after another of annular seals, that is, the power to flow towards the outlet at the low-pressure direction is reduced until the pressure of the leaked gas is equal to the pressure at the low-pressure end of the seal, and finally the anti-leakage effect is achieved. The most important defect of this sealing method is that it requires a sufficient axial distance to meet the placement space requirements of multiple stages of annular seals. At the same time, the too long axial distance affects the rotor dynamics characteristics and is not conducive to the operation safety of the whole machine.

[0003] Therefore, how to overcome the above defects has become an urgent problem to be solved by those skilled in the art at present. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a micro axial flow turbine seal device to shorten the axial distance.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a micro axial flow turbine seal device disposed between a housing and a rotating shaft, including: a micro axial flow turbine and multiple stages of annular seals arranged axially. A stage interval is formed between any two adjacent stages of the annular seals, and at least one of the stage intervals is provided with the micro axial flow turbine. The micro axial flow turbine includes a plurality of turbine blades arranged circumferentially along the rotating shaft, each of the turbine blades is fixedly connected to the rotating shaft, and each of the turbine blades can expand and depressurize the leaked gas, and when the leaked gas flows along the axis direction of the rotating shaft, each of the turbine blades can deflect the flow direction of the leaked gas.

[0007] Optionally, one end of the turbine blade is closer to the high-pressure side than the other end. The end of the turbine blade closer to the high-pressure side is the leading edge, and the other end is the trailing edge. The turbine blade has an arc-shaped structure or a nearly semi-circular structure from the leading edge to the trailing edge, and the opening of the arc-shaped structure or the opening of the nearly semi-circular structure faces the high-pressure side, so that the flow direction of the leakage gas is deflected by 180°.

[0008] Optionally, the thickness of the turbine blade gradually decreases from its leading edge to its trailing edge.

[0009] Optionally, both the leading edge end and the trailing edge end of the turbine blade are arc-shaped end faces.

[0010] Optionally, the side of the turbine blade facing the high-pressure side is the pressure surface, and the side facing the low-pressure side is the suction surface. The angle between the tangent direction of the outer contour of the suction surface of the leading edge of the turbine blade and the axis of the rotating shaft is the installation angle, and the installation angle is from 0° to 90°.

[0011] Optionally, the number of the micro axial-flow turbines is multiple, and all the micro axial-flow turbines are respectively arranged in the stage intervals at different positions.

[0012] Optionally, a plurality of first annular grooves and a plurality of second annular grooves are axially arranged on the inner wall of the housing. One second annular groove is arranged between any two adjacent first annular grooves. The annular seals correspond to the first annular grooves one by one. Each annular seal is partially embedded in the corresponding first annular groove, and gaskets for positioning adjacent two-stage annular seals are arranged in each second annular groove.

[0013] Optionally, the side of the turbine blade connected to the rotating shaft is the inner side, and the other side of the turbine blade opposite to the inner side is the outer side, and there is a gap between the outer side and the gasket.

[0014] Optionally, the annular seal is a carbon ring.

[0015] The present invention has achieved the following technical effects compared with the prior art:

[0016] The micro axial-flow turbine sealing device provided by the present invention is arranged between a housing and a rotating shaft, and includes: a micro axial-flow turbine and a plurality of axially arranged annular seals. A stage interval is formed between any two adjacent annular seals. At least one stage interval is provided with a micro axial-flow turbine. The micro axial-flow turbine includes a plurality of turbine blades arranged circumferentially along the rotating shaft. Each turbine blade is fixedly connected to the rotating shaft. Each turbine blade can expand and depressurize the leakage gas, and when the leakage gas flows along the axis direction of the rotating shaft, each turbine blade can deflect the flow direction of the leakage gas.

[0017] Compared with only setting multi-stage annular seals, the micro axial-flow turbine seal device provided by the present invention adds a micro axial-flow turbine. During the specific use process, the turbine blades rotate synchronously with the rotating shaft. When the leakage gas passes through the micro axial-flow turbine, the turbine blades can cause the leakage gas to expand and reduce pressure, so that the pressure of the leakage gas decreases. At the same time, the turbine blades can deflect the flow direction of the leakage gas, so that the gas flow rate flowing to the next-stage annular seal is reduced, and the sealing effect is improved. Compared with only setting multi-stage annular seals, the micro axial-flow turbine seal device provided by the present invention reduces the number of required annular seal stages by matching the micro axial-flow turbine with multi-stage annular seals, thereby effectively shortening the axial distance (the length of the rotating shaft). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a cross-sectional view of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the setting method of the micro axial-flow turbine of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of the arrangement method of the turbine blades of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0022] Figure 4 It is a schematic diagram of the structure of the housing of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0023] Figure 5 It is a schematic diagram of the velocity triangle of the turbine blades of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0024] Figure 6 It is a schematic diagram of the structure of the turbine blades of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0025] Figure 7 It is a schematic diagram of the cooperation mode between the turbine blades and the gasket of the micro axial-flow turbine seal device provided in the embodiment of the present invention;

[0026] Figure 8 It is a comparison diagram of the sealing effects between the micro axial-flow turbine seal device provided in the embodiment of the present invention and the conventional sealing method;

[0027] Figure 9 This is the sealing principle diagram of the micro axial-flow turbine sealing device provided in the embodiments of the present invention;

[0028] Figure 10 This is a schematic diagram of the sealing method of the non-contact seal mentioned in the background art;

[0029] Figure 11 This is the sealing principle diagram of the non-contact seal mentioned in the background art.

[0030] Figures 1-9 Explanation of reference numerals: 100, micro axial-flow turbine sealing device; 1, annular seal; 2, housing; 201, first annular groove; 202, second annular groove; 3, rotating shaft; 4, gap; 5, gasket; 6, clearance; 7, turbine blade; 701, suction surface; 702, pressure surface; 703, leading edge; 704, trailing edge.

[0031] Figures 10-11 Explanation of reference numerals: 1', rotating shaft; 2', annular seal. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] The purpose of the present invention is to provide a micro axial-flow turbine sealing device that can effectively shorten the axial distance.

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0035] Refer to Figures 1-9 As shown, the micro axial-flow turbine sealing device 100 provided in this embodiment is arranged between the housing 2 and the rotating shaft 3, and includes: a micro axial-flow turbine and a multi-stage annular seal 1 arranged axially. A stage interval is formed between any two adjacent stages of annular seals 1, and at least one stage interval is provided with a micro axial-flow turbine. The micro axial-flow turbine includes a plurality of turbine blades 7 arranged circumferentially along the rotating shaft 3. Each turbine blade 7 is fixedly connected to the rotating shaft 3, and each turbine blade 7 can expand and depressurize the leaked gas, and when the leaked gas flows along the axis direction of the rotating shaft 3, each turbine blade 7 can deflect the flow direction of the leaked gas.

[0036] Compared with only setting the multi-stage annular seal 1, the micro axial-flow turbine seal device 100 provided by the present invention adds a micro axial-flow turbine. During the specific use process, the turbine blades 7 rotate synchronously with the rotating shaft 3. When the leakage gas passes through the micro axial-flow turbine, the turbine blades 7 can cause the leakage gas to expand and reduce pressure, so that the pressure of the leakage gas decreases. At the same time, the turbine blades 7 can deflect the flow direction of the leakage gas, so that the gas flow rate flowing to the next-stage annular seal 1 is reduced, and the sealing effect is improved. Compared with only setting the multi-stage annular seal 1, the micro axial-flow turbine seal device 100 provided by the present invention reduces the number of stages of the required annular seal 1 by matching the micro axial-flow turbine with the multi-stage annular seal 1, thereby effectively shortening the axial distance (the length of the rotating shaft 3).

[0037] The micro axial-flow turbine seal device 100 provided in this embodiment couples the turbine into the existing conventional non-contact micro axial-flow turbine seal device 100. In the non-contact seal, the rotating shaft 3 serves as the turbine power shaft, and the principle of using the work output of the turbine to reduce pressure is used to achieve rapid pressure reduction with a short axial distance. At the same time, by using the guiding property of the curved surface of the turbine blade, the turning of the high-pressure inlet air flow is changed, avoiding the axial direct impact of the air flow towards the outlet, thereby reducing leakage and improving the sealing effect.

[0038] In this embodiment, as Figure 5 shown, one end of the turbine blade 7 is closer to the high-pressure side than the other end. The end of the turbine blade 7 close to the high-pressure side is the leading edge 703, and the other end is the trailing edge 704. The turbine blade 7 is in an arc structure or a near-semicircular structure from the leading edge 703 to the trailing edge 704, and the opening of the arc structure or the opening of the near-semicircular structure faces the high-pressure side, so that the flow direction of the leakage gas is deflected by 180°. By deflecting the flow direction of the leakage gas by 180 degrees, the deflected air flow can collide with the intake air flow, effectively hindering the flow of the intake air flow, and thus effectively improving the sealing effect. In addition, it should be noted that the near-semicircular structure includes the semicircular structure and the case that is basically in a semicircular structure.

[0039] Specifically, Figure 5 shows the velocity triangle of the turbine blade 7, Figure 5 in which the left side is the high-pressure inlet, the right side is the low-pressure outlet, the high-pressure air flow enters from the left, the axial velocity is upward, the inlet absolute velocity is axially to the right, the axial velocity plus the relative velocity equals the absolute velocity, and the air flow flows from the leading edge 703 along the blade surface to the trailing edge 704. At the trailing edge 704, the outlet absolute velocity is opposite to the inlet absolute velocity direction of the leading edge 703. Figure 5 In it, W1 is the inlet relative velocity of the turbine blade 7, W2 is the outlet relative velocity of the turbine blade 7, V1 is the inlet absolute velocity of the turbine blade 7, V2 is the outlet absolute velocity of the turbine blade 7, and U is the rim velocity.

[0040] It should be noted that the turbine blade 7 is not limited to deflecting the flow direction of the leakage gas by 180 degrees, but can also be any other angle, and the specific angle depends on the shape of the turbine blade 7. As long as the flow direction of the air flow deflects relative to the axis direction of the rotating shaft 33, the air flow rate flowing to the next-stage annular seal 1 can be reduced, thereby improving the sealing effect.

[0041] In this embodiment, specifically, as Figure 5 shown, the thickness of the turbine blade 7 gradually thins from its leading edge 703 to its trailing edge 704.

[0042] In this embodiment, specifically, as Figure 5 shown, both the end of the leading edge 703 and the end of the trailing edge 704 of the turbine blade 7 are arc-shaped end faces.

[0043] In this embodiment, specifically, as Figure 5 shown, the side of the turbine blade 7 facing the high-pressure side is the pressure surface 702, and the side facing the low-pressure side is the suction surface 701. The included angle between the tangent direction of the outer contour of the suction surface 701 of the leading edge 703 of the turbine blade 7 and the axis of the rotating shaft 3 is the installation angle, and the installation angle is from 0° to 90°, and the specific value of the installation angle is determined according to the actual situation.

[0044] In this embodiment, the number of micro axial-flow turbines is multiple, and all the micro axial-flow turbines are respectively arranged in the stage intervals at different positions, and the specific number of the micro axial-flow turbines is determined according to the actual situation.

[0045] In this embodiment, specifically, as Figure 4 shown, a plurality of first annular grooves 201 and a plurality of second annular grooves 202 are axially arranged on the inner wall of the housing 2. A second annular groove 202 is arranged between any two adjacent first annular grooves 201. The first annular grooves 201 and the second annular grooves 202 are arranged at intervals. The annular seals 1 correspond to the first annular grooves 201 one by one, and each annular seal 1 is partially embedded in its corresponding first annular groove 201. Gaskets 5 for positioning adjacent two-stage annular seals 1 are arranged in each second annular groove 202.

[0046] In this embodiment, specifically, as Figure 7 and Figure 9 shown, the side of the turbine blade 7 connected to the rotating shaft 3 is the inner side, and the other side of the turbine blade 7 opposite to the inner side is the outer side, and there is a gap 6 between the outer side and the gasket 5.

[0047] In this embodiment, specifically, the annular seal 1 is a carbon ring. It should be noted that the annular seal 1 is not limited to being a carbon ring, and other annular sealing structures can also be selected to act as the annular seal 1.

[0048] During specific use, the turbine blades 7 are designed and matched according to the rotation direction of the rotating shaft 3, the pressure conditions before and after the micro axial-flow turbine sealing device 100, and the size of the gap 4 between the annular seal 1 and the rotating shaft 3. The design content includes: Figure 5 the configurations of the suction surface 701 and the pressure surface 702 of the shown turbine blade 7, Figure 6 the height H of the shown turbine blade 7, the installation angle α of the turbine blade 7 shown in the figure, the solidity of the turbine blade 7, and Figure 7 the gap 6 between the outer side of the shown turbine blade 7 and the gasket 5.

[0049] Figure 8 Fig. shows a comparison diagram of the sealing effects between the micro axial-flow turbine sealing device 100 provided in this embodiment and the conventional sealing method. The placement position of the axial seal corresponds to the line graph. Figure 8 In this embodiment, the micro axial-flow turbine sealing device 100 provided takes a two-stage micro axial-flow turbine coupled with a three-stage carbon ring seal (with the micro axial-flow turbine sealing method) as an example, and the conventional sealing method takes a multi-stage carbon ring seal (without the micro axial-flow turbine sealing method) as an example. Since the conventional sealing method does not have a micro axial-flow turbine, there is a cavity between the gasket 5 and the rotating shaft 3. The abscissa is the axial direction from the high-pressure inlet to the low-pressure outlet, and the ordinates are the total pressure and the leakage rate respectively. Under the same inlet pressure and the same shaft speed, the sealing method with the micro axial-flow turbine provided in this embodiment reaches the pressure value at the low-pressure outlet faster than the conventional sealing method without the micro axial-flow turbine, and the leakage rate is much lower than that of the conventional sealing method without the micro axial-flow turbine. The conventional sealing method without the micro axial-flow turbine needs to increase several stages to reach the pressure value at the low-pressure outlet, and no matter how many stages of carbon rings there are, the last stage of the carbon ring plays a greater pressure-reducing role than the previous stages of carbon rings. From the area near the outlet of the carbon ring to the outlet area, there is a large pressure drop. Compared with the conventional sealing method without the micro axial-flow turbine, the micro axial-flow turbine of the sealing method with the micro axial-flow turbine provided in this embodiment provides the main pressure-reducing function and has the function of preventing the air flow from directly rushing towards the outlet. Therefore, there is no large pressure drop at the outlet of the last stage of the carbon ring sealed by the sealing method with the micro axial-flow turbine provided in this embodiment. Therefore, the final anti-leakage effect is better than that of the sealing method without the micro axial-flow turbine with increased stages.

[0050] It should be noted that compared with the conventional axial-flow turbine, the turbine in the present invention is arranged between the housing 2 and the rotating shaft 3. The size of the turbine in the present invention is much smaller than that of the conventional axial-flow turbine. Therefore, the turbine in the present invention is called a micro axial-flow turbine. Here, "micro" does not mean that the size of the turbine is smaller than a certain value. The size of the micro axial-flow turbine is adjusted according to the sealing requirements.

[0051] In this specification, specific examples are used to illustrate the principles and implementation manners of the present invention. The description of the above embodiments is only for helping to understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A micro axial flow turbine sealing device is arranged between a housing and a rotating shaft, and is characterized in that, Comprising: A micro axial-flow turbine and a multi-stage annular seal arranged axially. A stage interval is formed between any two adjacent stages of the annular seals. At least one of the stage intervals is provided with the micro axial-flow turbine. The micro axial-flow turbine includes a plurality of turbine blades arranged circumferentially along the rotating shaft. Each of the turbine blades is fixedly connected to the rotating shaft. Each of the turbine blades can expand and depressurize the leakage gas, and when the leakage gas flows along the axis direction of the rotating shaft, each of the turbine blades can deflect the flow direction of the leakage gas; one end of the turbine blade is closer to the high-pressure side than the other end. The end of the turbine blade closer to the high-pressure side is the leading edge, and the other end is the trailing edge. The turbine blade is in an arc-shaped structure or a nearly semi-circular structure from the leading edge to the trailing edge, and the opening of the arc-shaped structure or the opening of the nearly semi-circular structure faces the high-pressure side, so that the flow direction of the leakage gas is deflected by 180°.

2. The micro axial flow turbine sealing device according to claim 1, characterized in that, The thickness of the turbine blade gradually thins from its leading edge to its trailing edge.

3. The micro axial flow turbine sealing device according to claim 1, characterized in that, Both the leading edge end and the trailing edge end of the turbine blade are arc-shaped end faces.

4. The micro axial flow turbine sealing device according to claim 1, characterized in that, The side of the turbine blade facing the high-pressure side is the pressure surface, and the side facing the low-pressure side is the suction surface. The included angle between the tangent direction of the outer contour of the suction surface of the leading edge of the turbine blade and the axis of the rotating shaft is the installation angle, and the installation angle is from 0° to 90°.

5. The micro axial flow turbine sealing device according to claim 1, characterized in that, The number of the micro axial-flow turbines is multiple, and all the micro axial-flow turbines are respectively arranged in the stage intervals at different positions.

6. The micro axial flow turbine sealing device according to claim 1, characterized in that, A plurality of first annular grooves and a plurality of second annular grooves are axially arranged on the inner wall of the housing. One of the second annular grooves is arranged between any two adjacent first annular grooves. The annular seals correspond to the first annular grooves one by one. Each of the annular seals is partially embedded in the corresponding first annular groove. A gasket for positioning two adjacent stages of the annular seals is arranged in each of the second annular grooves.

7. The micro axial flow turbine sealing device according to claim 6, characterized in that, The side of the turbine blade connected to the rotating shaft is the inner side, and the other side of the turbine blade opposite to the inner side is the outer side, and there is a gap between the outer side and the gasket.

8. The micro axial flow turbine sealing device according to claim 1, characterized in that, The annular seal is a carbon ring.

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