End seal structure of steam turbine and steam turbine

Abstract

This invention relates to the field of steam turbine technology, and more particularly to an end-seal structure for a steam turbine and a steam turbine employing this end-seal structure. The end-seal structure includes a cylinder and a turbine rotor with a clearance fit. A seal chamber is formed at the end of the cylinder closest to the outside. Seal rings are respectively engaged on both sides of the seal chamber. Seal teeth for throttling and engaging with the seal teeth on the seal rings are inlaid or machined on the outer surface of the turbine rotor. A guide vane extends continuously circumferentially on the outer surface of the turbine rotor, with a height higher than the height of the seal teeth. The guide vane is located between the seal rings on both sides of the seal chamber. The guide vane can block the jet flow, preventing the steam flow from the outlet of the seal ring far from the outside from directly impacting the inlet of the seal ring close to the outside, ensuring that the pressure at the inlet of the seal ring close to the outside does not exceed the outside atmospheric pressure, thereby giving the steam turbine good airtightness when the seal system is functioning properly.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, and more particularly to an end seal structure for a steam turbine and a steam turbine employing the end seal structure. Background Technology

[0002] See Figure 1 The steam in cylinder 1 of the steam turbine is throttled by multiple steam seal rings b, resulting in pressure dissipation. The steam is then recovered by the slightly negative pressure shaft seal heater. Simultaneously, a small amount of outside air is drawn into the shaft seal heater. Steam seal chamber a is the last leaking chamber before the end steam seal outlet of the steam turbine. It is connected to the shaft seal heater via a pipe, and multiple steam seal rings b are installed on both sides of steam seal chamber a. The shaft seal heater maintains a slightly negative pressure environment, approximately 1 kPa lower than atmospheric pressure. Due to flow pressure loss, when the pressure at steam seal chamber a is approximately 0.5 kPa lower than atmospheric pressure or slightly lower, the steam in the cylinder can be completely drawn away by the end steam seal system, preventing steam leakage.

[0003] For existing end-seal designs, improving shaft seal performance typically focuses on optimizing the seal between the turbine's moving and stationary components. This involves continuously reducing the seal gap and increasing the complexity of the seal flow channel, such as optimization measures with brush-type seals, seal teeth mounted on the seal ring or rotor surface, optimization measures with labyrinth vortex chambers, and optimization methods with honeycomb seals. However, due to limited axial space, and the fact that excessively long seal rings continuously arranged on both sides of the seal chamber can easily cause gap vibration, which is detrimental to shaft stability, the number of seal rings and seal teeth is limited. Therefore, the jet energy at the outlet of seal ring b on the upstream side of seal chamber a remains relatively high. See also Figure 1 Steam sealing rings b are provided on both the left and right sides of the steam sealing chamber a. The right side of the steam sealing chamber a is the upstream side, and the left side is the downstream side. Under certain special operating conditions or when the steam sealing teeth are worn, the jet at the outlet of the upstream steam sealing ring b of the steam sealing chamber a may directly impact the inlet of the downstream steam sealing ring b of the steam sealing chamber a. Since the steam flow has a high velocity, it converts kinetic energy into static pressure after being blocked, which increases the static pressure at the inlet of the downstream steam sealing ring b of the steam sealing chamber a. Even if the steam sealing chamber a is in a slightly negative pressure state, the inlet of the downstream steam sealing ring b of the steam sealing chamber a will still be higher than the external atmospheric pressure, resulting in steam leakage. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides an end steam seal structure for a steam turbine that enables the steam turbine to have good airtightness when the steam sealing system is working well.

[0005] The present invention adopts the following technical solution:

[0006] This invention provides an end seal structure for a steam turbine, including a cylinder and a steam turbine rotor with clearance fit. A seal chamber is provided at the end of the cylinder near the outside. Seal rings are respectively snapped into both sides of the seal chamber. Seal teeth for throttling are inlaid or machined on the outer surface of the steam turbine rotor and cooperate with the seal teeth on the seal rings. A guide element is continuously extended circumferentially on the outer surface of the steam turbine rotor. The height of the guide element is higher than the height of the seal teeth. The guide element is located between the seal rings on both sides of the seal chamber.

[0007] Preferably, the guide element is a guide tooth embedded in the turbine rotor.

[0008] Preferably, multiple guide teeth are provided, and the multiple guide teeth are continuously and spaced apart from the outlet of the steam seal ring on the side of the steam turbine rotor near the steam seal chamber to the outlet of the steam seal ring on the other side of the steam turbine rotor near the steam seal chamber.

[0009] Preferably, the height of multiple guide teeth, which are continuously spaced from the outlet of the steam seal ring on the side of the turbine rotor near the steam seal chamber to the outlet of the steam seal ring on the other side of the turbine rotor near the steam seal chamber, gradually increases and then gradually decreases.

[0010] Preferably, the angle α between the guide tooth and the side of the turbine rotor closest to the outside is 30°-90°.

[0011] Preferably, the turbine rotor has a stepped shaft section between the steam seal rings on both sides of the steam seal chamber, and the turbine rotor is provided with guide teeth at the outlet of the steam seal rings near both sides of the steam seal chamber.

[0012] Preferably, the guide element is a guide structure formed during the machining of the turbine rotor.

[0013] Preferably, the turbine rotor has a stepped shaft section between the steam seal rings on both sides of the steam seal chamber, and the flow guiding structure is located at the large diameter position of the stepped structure.

[0014] Preferably, the turbine rotor has multiple flow guiding structures continuously spaced within the space between the steam sealing rings on both sides of the steam sealing chamber, and the height of the multiple flow guiding structures gradually decreases towards the steam sealing rings on both sides of the steam sealing chamber.

[0015] The present invention also provides a steam turbine employing the end steam seal structure of the steam turbine as described in any of the preceding claims.

[0016] Compared with the prior art, the present invention has significant progress:

[0017] The guide vane can block the jet, preventing the steam flow from the steam seal ring outlet far from the outside from directly impacting the inlet area of ​​the steam seal ring near the outside. This avoids the static pressure rise at the inlet of the steam seal ring near the outside and ultimately ensures that the pressure at the inlet of the steam seal ring near the outside is not higher than the outside atmospheric pressure. As a result, the steam turbine has good airtightness when the steam seal system is working well. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the steam flow direction of the end steam seal structure in the background art of this invention (wherein, the direction of the solid arrow is the normal flow direction of the steam flow, and the direction of the hollow arrow is the leakage flow direction of the steam flow).

[0019] Figure 2 This is a schematic diagram of the steam flow direction of the end steam seal structure in Embodiment 1 of the present invention (wherein, the direction of the solid arrow is the direction of the steam flow).

[0020] Figure 3 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment 1 of the present invention.

[0021] Figure 4 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment 2 of the present invention.

[0022] Figure 5 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment 3 of the present invention.

[0023] Figure 6 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment 4 of the present invention.

[0024] Figure 7 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment 5 of the present invention.

[0025] Figure 8 This is a schematic diagram of the end steam seal structure of the steam turbine in Embodiment Six of the present invention.

[0026] The reference numerals in the attached figures are explained as follows:

[0027] 1. Cylinder

[0028] 2. Steam turbine rotor

[0029] 3. Airflow guide

[0030] a. Steam seal chamber

[0031] b. Steam seal ring Detailed Implementation

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0036] It should be noted that, in the present invention Figures 2 to 8 In the diagram, the leftmost side of the paper represents the outside, and the rightmost side represents the inside of cylinder 1.

[0037] Example 1

[0038] like Figures 2 to 3 The image shows a first embodiment of the end steam seal structure of the steam turbine of the present invention.

[0039] See Figure 2The end-seal structure of the steam turbine in this embodiment includes a cylinder 1 with clearance fit and a steam turbine rotor 2. A seal chamber a is provided at the end of the cylinder 1 closest to the outside. Seal rings b are respectively engaged on both sides of the seal chamber a. Seal teeth for throttling are inlaid or machined on the outer surface of the steam turbine rotor 2 and engage with the seal teeth on the seal rings b. A guide member 3 extends continuously along the circumference on the outer surface of the steam turbine rotor 2. The height of the guide member 3 is higher than the height of the seal teeth, and the guide member 3 is located between the seal rings b on both sides of the seal chamber a. The guide member 3 can block the jet flow, preventing the steam flow from the outlet of the seal ring b, which is far from the outside, from directly impacting the inlet area of ​​the seal ring b, which is close to the outside. This avoids an increase in static pressure at the inlet of the seal ring b, which is close to the outside, and ultimately ensures that the pressure at the inlet of the seal ring b, which is close to the outside, is not higher than the outside atmospheric pressure. Therefore, the steam turbine has good airtightness when the seal system is working well.

[0040] Preferably, in this embodiment, the type of steam seal ring b is not specified, and it can be an interlaced tooth steam seal ring, a flat tooth steam seal ring, a side tooth steam seal ring, a contact steam seal ring, a honeycomb steam seal ring, or a spiral steam seal ring; and in this embodiment, the steam seal teeth are embedded on the outer surface of the turbine rotor 2.

[0041] Preferably, see Figure 3 The guide element 3 is a guide tooth embedded in the turbine rotor 2. The guide element 3 and the turbine rotor 2 are connected by embedding, which helps to reduce the processing difficulty of the guide element 3 and reduce production costs.

[0042] It should be noted that the guide teeth are designed according to conventional steam seal teeth, and the thickness of the guide teeth is not specified. The cross-sectional shape can be a simple thin sheet or a thicker boss. However, the distance between the guide teeth and the steam seal rings b on both sides of the steam seal chamber 2 needs to be considered. Under any operating condition, the guide teeth must not rub against the steam seal rings b on both sides of the steam seal chamber 2.

[0043] Preferably, see Figure 3 Multiple guide teeth are provided, and these guide teeth are continuously spaced from the outlet of the steam seal ring b on the side of the turbine rotor 2 closest to the steam seal chamber a to the outlet of the steam seal ring b on the other side of the turbine rotor 2 closest to the steam seal chamber a. The continuous and spaced arrangement of multiple guide teeth can enhance the blocking effect on the jet and ultimately enable the turbine to have good airtightness when the steam seal system is working well.

[0044] Preferably, see Figure 3Multiple guide teeth, spaced continuously at intervals from the outlet of the steam seal ring b on the side of the turbine rotor 2 closest to the steam seal chamber a, to the outlet of the steam seal ring b on the other side of the turbine rotor 2 closest to the steam seal chamber a, have a height that gradually increases and then gradually decreases. This variation in the height of the multiple guide teeth guides the steam flow exiting from the outlet of the steam seal ring b, which is farther from the outside, directing the steam flow smoothly towards the steam seal chamber a, thereby reducing the pressure loss of the steam seal recovery system.

[0045] Specifically, see Figure 3 In this first embodiment, there are three guide teeth. One of the guide teeth is the tallest and is located between the other two guide teeth. The other two guide teeth are the same height and are respectively located near the outlet of the steam seal ring b on the side of the steam seal chamber a.

[0046] This embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0047] Example 2

[0048] like Figure 4 The image shows a second embodiment of the turbine end seal structure of the present invention. Embodiment two is essentially the same as embodiment one, and the similarities will not be repeated. The difference lies in that, in this embodiment two, the angle α between the guide teeth and the side of the turbine rotor 2 closest to the outside is 30°-90°, so that the guide teeth can effectively guide the steam flow from the outlet of the steam seal ring b, which is far from the outside, guiding the steam flow smoothly towards the steam seal chamber a, thereby reducing the pressure loss of the steam seal recovery system. It should be noted that, for ease of processing and assembly, a rounded corner is permissible at the point where the turbine rotor 2 engages with the guide teeth.

[0049] This embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0050] Example 3

[0051] like Figure 5 The image shows a third embodiment of the end steam seal structure of the steam turbine according to the present invention. Embodiment three is basically the same as embodiment one, and the similarities will not be repeated. The difference lies in that the shaft section of the steam turbine rotor 2 between the steam seal rings b on both sides of the steam seal chamber a has a stepped structure, and the steam turbine rotor 2 is provided with guide teeth at the outlet of the steam seal rings b on both sides near the steam seal chamber a. The stepped structure, together with the guide teeth, can further enhance the blocking effect on the jet, and ultimately enable the steam turbine to have good airtightness when the steam seal system is working well.

[0052] This embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0053] Example 4

[0054] like Figure 6 The image shows a fourth embodiment of the end steam seal structure of the steam turbine according to the present invention. This fourth embodiment is basically the same as the first embodiment, and the similarities will not be repeated. The difference lies in that the guide element 3 is a guide structure formed during the machining of the steam turbine rotor 2. The guide element 3 and the steam turbine rotor 2 are an integral structure, which helps to improve the structural strength of the guide element 3 and extend its service life.

[0055] It should be noted that the flow guiding structure can be processed into different shapes and flow guiding surfaces according to the actual steam flow conditions, so as to block the jet and guide the steam flow from the outlet of the steam seal ring b, which is far away from the outside, and guide the steam flow smoothly to the steam seal chamber a, thereby reducing the pressure loss of the steam seal recovery system.

[0056] Better, see Figure 6 In this fourth embodiment, the radial cross-sectional shape of the flow guiding structure is an equilateral triangle.

[0057] This embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0058] Example 5

[0059] like Figure 7 The image shows a fifth embodiment of the end steam seal structure of the steam turbine of the present invention. This fifth embodiment is basically the same as the fourth embodiment, and the similarities will not be repeated. The difference is that the shaft section of the steam turbine rotor 2 between the steam seal rings b on both sides of the steam seal chamber a is a stepped structure, and the flow guiding structure is set at the large diameter position of the stepped structure.

[0060] Better yet, see Figure 7 In this fifth embodiment, the flow guiding structure has a flow guiding surface on the side near the steam seal ring b, which is far from the outside. The flow guiding surface extends obliquely towards the steam seal ring b, which is far from the outside. The flow guiding surface can guide the steam flow from the outlet of the steam seal ring b, which is far from the outside, and guide the steam flow smoothly to the steam seal chamber a, thereby reducing the pressure loss of the steam seal recovery system.

[0061] This fifth embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0062] Example 6

[0063] like Figure 8The image shows a sixth embodiment of the end steam seal structure of the steam turbine according to the present invention. This sixth embodiment is basically the same as the fourth embodiment, and the similarities will not be repeated. The difference lies in that multiple flow guiding structures are continuously and intermittently arranged in the space between the steam seal rings b on both sides of the steam seal chamber a. The height of these multiple flow guiding structures gradually decreases towards the steam seal rings b on both sides of the steam seal chamber a. This gradual decrease in the height of the multiple flow guiding structures towards the steam seal rings b on both sides of the steam seal chamber a can guide the steam flow exiting from the steam seal rings b, which are far from the outside, guiding the steam flow smoothly towards the steam seal chamber a, thereby reducing the pressure loss of the steam seal recovery system.

[0064] Better yet, see Figure 8 In this sixth embodiment, the flow guiding structure is provided with a flow guiding surface, and the flow guiding surface on the lower flow guiding structure of two adjacent flow guiding structures is inclined towards the higher flow guiding structure. The arrangement of multiple flow guiding surfaces on multiple flow guiding structures can further enhance the flow guiding effect for the steam flowing out of the outlet of the steam sealing ring b, which is far from the outside, and guide the steam flow to the steam sealing chamber a more smoothly, thereby further reducing the pressure loss of the steam sealing recovery system.

[0065] Specifically, see Figure 8 In this sixth embodiment, there are two flow guiding structures, one of which is higher than the other, and the flow guiding structure with the lower height is located near the outlet of the steam seal ring b, which is far away from the outside.

[0066] This embodiment also provides a steam turbine that adopts the end steam seal structure of the steam turbine as described above.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. An end seal structure for a steam turbine, comprising a cylinder and a steam turbine rotor with clearance fit, wherein a seal chamber is provided at one end of the cylinder near the outside, and seal rings are respectively engaged on both sides of the seal chamber; and seal teeth for throttling are provided on the outer surface of the steam turbine rotor, which engage with the seal teeth on the seal rings, characterized in that, A guide member is formed continuously along the circumferential direction on the outer surface of the turbine rotor. The height of the guide member is higher than the height of the steam seal tooth. The guide member is located between the steam seal rings on both sides of the steam seal chamber. The guide member is a guide tooth embedded in the turbine rotor. There are multiple guide teeth. The multiple guide teeth are continuously and spaced apart from the outlet of the steam seal ring on the side of the turbine rotor near the steam seal chamber to the outlet of the steam seal ring on the other side of the turbine rotor near the steam seal chamber. The height of the multiple guide teeth that are continuously and spaced apart from the outlet of the steam seal ring on the side of the turbine rotor near the steam seal chamber to the outlet of the steam seal ring on the other side of the turbine rotor near the steam seal chamber first gradually increases and then gradually decreases.

2. The end steam seal structure of the steam turbine according to claim 1, characterized in that, The angle α between the guide tooth and the side of the turbine rotor closest to the outside is 30°-90°.

3. The end steam seal structure of the steam turbine according to claim 1, characterized in that, The turbine rotor has a stepped shaft section between the steam seal rings on both sides of the steam seal chamber, and the turbine rotor is provided with guide teeth at the outlet of the steam seal rings near both sides of the steam seal chamber.

4. A steam turbine, characterized in that, The turbine end seal structure as described in any one of claims 1-3 is adopted.

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