A sealing structure based on circumferential relative speed

Abstract

The present invention relates to a sealing structure based on circumferential relative speed, comprising a head: the head is annular, and a protruding annular sealing tooth is formed on the inner circumference of the head; a sealing body: the sealing body is annular, and a concave annular sealing groove is formed on the outer circumference of the sealing body. When the head and the sealing body are matched, the head is coaxially sleeved on the outer side of the sealing body, and the sealing tooth of the head is inserted into the sealing groove of the sealing body. The sealing structure also includes a blade component, and the blade component includes at least one of a plurality of first concave surfaces arranged on one side end face of the head and a plurality of blades arranged in the sealing groove of the sealing body, and the blade surface of the blade faces one side. The present invention uses the blade structure designed by the kinetic energy of the working fluid in circumferential motion to reduce or block the flow rate and leakage of the working fluid flowing through the sealing structure. The higher the circumferential motion speed of the working fluid, the higher the available circumferential kinetic energy, and the better the sealing performance.

Description

Technical Field

[0001] The invention belongs to the field of steam turbines, and in particular relates to a sealing structure based on circumferential relative speed. Background Art

[0002] During the normal operation of the steam turbine, there is a certain radial clearance when the internal main shaft passes through the cylinder, and the effect of the steam pressure difference causes the interstage steam to leak from the high-pressure end to the low-pressure end in the gap between the main shaft and the partition, and between the cylinder (or partition sleeve) and the top of the moving blade. In addition, there is also steam leakage from high pressure to low pressure at both ends of each cylinder of the steam turbine. It is precisely because of these problems that the efficiency of each stage of the steam turbine is reduced.

[0003] Steam seal is an important part of steam turbine structure. Practice has proved that during the overhaul of steam turbine, the relative internal efficiency of steam turbine can be significantly improved by adjusting the steam seal gap, modifying the steam seal structure, and improving the tightness of the steam seal of the flow part of the steam turbine. In order to reduce steam leakage loss and improve the safety and economy of the unit, many new steam seals have appeared in the past decade. The traditional labyrinth steam seal is a non-contact steam seal, which generally adopts a tooth structure, including several typical structures such as high and low teeth, flat teeth, oblique flat teeth, fir teeth, and inlaid teeth. Due to its simple structure, mature technology, safety and reliability, it is still widely used in steam turbines, especially in large steam turbines, where labyrinth steam seals are still the main sealing form.

[0004] In view of the possible problems of traditional labyrinth steam seals, in order to ensure the safety of unit operation and improve unit efficiency, research on new steam seal structures, materials, processes, theoretical calculations, tests and operating characteristics has been carried out at home and abroad. Among them, the most widely studied ones include honeycomb steam seals, brush steam seals, contact steam seals, adjustable steam seals, eddy current steam seals, etc. At the same time, the transformation of traditional steam seals for old units is also continuing, and has achieved certain results in reducing heat consumption, increasing vacuum, and improving lubricating oil quality. The research on new steam seals and the success achieved in the transformation of old units, some new steam seals such as honeycomb steam seals and brush steam seals have been used on new units.

[0005] The function of the steam seal is to minimize the gap between the moving and static components inside the steam turbine, bypass the throughflow, and flow from the relatively high pressure area to the relatively low pressure area. The steam flow near the steam seal inlet and in its internal structure is not a simple axial flow. The actual flow situation is more complicated. There are certain flow velocities in the axial, circumferential and radial directions, and there are vortices in the steam seal structure. The current steam seal technology mainly achieves the purpose of blocking flow and slowing down the axial flow speed by reducing the gap between the steam seal plate and the steam seal groove and enhancing the axial vortex in the steam seal. There are fewer technologies that use the circumferential movement speed of steam. Some literature has been used to enhance the circumferential vortex of steam flow inside the steam seal structure. Summary of the invention

[0006] An object of the present invention is to provide a sealing structure based on circumferential relative speed.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A sealing structure based on circumferential relative velocity, comprising:

[0009] Sealing head: the sealing head is annular, and the inner circumference of the sealing head is formed with protruding annular sealing teeth;

[0010] Sealing body: The sealing body is annular, and a concave annular sealing groove is formed on the outer circumference of the sealing body.

[0011] When the sealing head and the sealing body are matched, the sealing head is coaxially sleeved on the outside of the sealing body, and the sealing teeth of the sealing head are inserted into the sealing grooves of the sealing body.

[0012] The sealing structure also includes a blade assembly, which includes at least one of a plurality of first concave surfaces arranged on one end surface of the head and a plurality of blades arranged in the sealing groove of the sealing body, and the blade surface of the blade faces one side.

[0013] Preferably, the sealing teeth of the sealing head and the sealing grooves of the sealing body are both provided in plurality, and each sealing tooth of the sealing head is inserted into a sealing groove of the sealing body.

[0014] Preferably, the blade profile assembly further includes a plurality of second concave surfaces arranged on a side surface of the sealing teeth of the head.

[0015] Further preferably, the plurality of second concave surfaces are evenly distributed around the side surface of the sealing head and teeth.

[0016] Preferably, the blades are arranged obliquely relative to the extension direction of the sealing groove.

[0017] Preferably, the plurality of blades are evenly distributed around the sealing groove of the sealing body.

[0018] Preferably, the plurality of first concave surfaces are evenly distributed around the end surface of the head.

[0019] Preferably, the sealing structure is a steam seal structure, a shaft seal structure, a water seal structure, or an oil seal structure. The sealing structure is applicable to the steam seal structure and the shaft seal structure inside the steam turbine. According to the local structure and steam parameters of the steam seal structure and the shaft seal structure, a specific blade type component is designed and arranged on the end face of the seal head or in the windward direction of the seal groove of the seal body. After installation, the steam leakage flow of the steam seal structure and the shaft seal structure can be reduced or blocked, greatly improving the sealing performance of the steam seal structure and the shaft seal structure and improving the efficiency of the steam turbine. It is also applicable to similar sealing structures that can utilize the circumferential movement of the medium, such as the water seal structure of the water pump and the oil seal structure of the oil stop.

[0020] Further preferably, the steam seal structure is a blade tip steam seal, a bridge steam seal, or a partition steam seal.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] The present invention utilizes the kinetic energy of the circumferential motion of the working fluid to design a blade structure, thereby reducing or blocking the flow and leakage of the working fluid flowing through the sealing structure. The higher the circumferential motion speed of the working fluid, the higher the available circumferential kinetic energy and the better the sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 It is a structural schematic diagram of a blade tip steam seal in the prior art;

[0024] Attached Figure 2 It is a structural schematic diagram of embodiment 1;

[0025] Attached Figure 3 It is a structural schematic diagram of Embodiment 2;

[0026] Attached Figure 4 It is a schematic diagram of the structure of the sealing body in the second embodiment;

[0027] Attached Figure 5 This is a schematic diagram of the structure of Embodiment 3;

[0028] Attached Figure 6 It is a schematic diagram of the structure of three heads in the embodiment.

[0029] Among them: 1, sealing head; 10, sealing teeth; 100, second concave surface; 11, first concave surface; 2, sealing body; 20, sealing groove; 21, blades. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] This embodiment takes a simplified blade tip steam seal as an example, which includes a seal head 1 and a seal body 2. Among them:

[0034] like Figure 1 As shown: the head 1 and the sealing body 2 are annular, the inner circumference of the head 1 is formed with protruding annular sealing teeth 10, and the outer circumference of the sealing body 2 is formed with a concave annular sealing groove 20. When the head 1 and the sealing body 2 are matched, the head 1 is coaxially sleeved on the outside of the sealing body 2, and the sealing teeth 10 of the head 1 and the sealing grooves 20 of the sealing body 2 are both provided in plurality, and each sealing tooth 10 of the head 1 is inserted into a sealing groove 20 of the sealing body 2. The head 1 is installed on the inner wall of the inner cylinder and is in a stationary state relative to the turbine casing, and the sealing body 2 is installed on the top of the moving blade and moves counterclockwise with the rotor.

[0035] Steam enters the seal body from the windward side of the blade tip seal and flows to the leeward side through the narrow channel in the seal structure. At the same time, the steam has both axial and circumferential motion speeds when flowing through the seal structure. The initial axial angular velocity of the steam at the seal structure entrance is basically equivalent to the angular velocity of the rotor, and the angular velocity of the rotor is 100π / s (taking a 3000r / min steam turbine as an example). If calculated based on the average diameter of the seal structure channel at this location of 1m, the initial circumferential linear velocity of the steam entering the seal structure is 157.1m / s. The ultimate pressure that can be used for the circumferentially moving steam is the stagnation pressure of the circumferential motion of the steam, and the calculation formula is:

[0036]

[0037] in:

[0038] p c,s ——Stagnation partial pressure of steam circumferential flow, MPa;

[0039] ρ——steam density, kg / m3;

[0040] v – circumferential flow velocity of steam, m / s.

[0041] The calculation of the circumferential partial pressure of steam is shown in Table 1. After entering the steam seal body, the circumferential velocity gradually decays. As shown in Table 1, the circumferential partial pressure that can be used by the steam leaking into the seal groove 20 is basically comparable to the pressure drop of a single seal groove 20. Therefore, the prerequisite for using the circumferential velocity of steam is met.

[0042] Calculation of the circumferential partial pressure of steam at a diameter of 1m under the parameters in Table 1 (unit: MPa):

[0043]

[0044] This embodiment utilizes the circumferential relative velocity of the steam flow and arranges blade components at the moving and static parts so that the steam can obtain a certain axial reverse flow ability after flowing through the blade components and merge with the steam in the mainstream direction, thereby reducing the mainstream steam flow rate.

[0045] Embodiment 1 (windward side):

[0046] like Figure 2 As shown: the blade assembly includes a plurality of blade-shaped first concave surfaces 11 arranged on the end surface of the windward side of the head 1, and the plurality of first concave surfaces 11 are evenly distributed around the end surface of the head 1. At the windward side of the steam seal structure, the first concave surfaces 11 are evenly arranged in the circumferential velocity direction, and the flow direction of the steam after leaving the first concave surfaces 11 is changed by utilizing the circumferential velocity of the steam, and the steam flow in the mainstream direction can be slowed down.

[0047] Embodiment 2 (active slot sealing blade):

[0048] like Figure 3 , 4 As shown: the blade assembly includes a plurality of blades 21 arranged in the sealing groove 20 of the sealing body 2, the blade surface of the blade 21 faces the windward side, and the blade 21 is inclined relative to the extension direction of the sealing groove 20, and the plurality of blades 21 are evenly distributed around the sealing groove 20 of the sealing body 2. In this embodiment, the rotation of the rotating shaft drives the blades 21 to move circumferentially with the sealing body 2, so that the steam at the outlet between the blades 21 obtains a reverse flow speed to offset the steam flow in the mainstream direction in part of the steam seal structure. According to the local steam parameters (or working fluid parameters), by controlling the blade type, number, equivalent diameter and other parameters of the blades 21 in the sealing groove 20 at the top of the moving blade, relatively matching structural parameters can be obtained.

[0049] Embodiment 3 (passive concave end cap):

[0050] like Figure 5 , 6 As shown: the blade assembly includes a plurality of blade-shaped first concave surfaces 11 arranged on the end surface of the windward side of the head 1, and a plurality of second concave surfaces 100 arranged on the windward side of the sealing teeth 10 of the head 1. The plurality of first concave surfaces 11 are evenly distributed around the end surface of the head 1, and the plurality of second concave surfaces 100 are evenly distributed around the side surface of the sealing teeth 10 of the head 1. This embodiment utilizes the head 1 and the circumferential flow velocity of the steam entering the steam seal structure, so that when the circumferential flow passes through the head 1 with the blade-shaped concave surface, the flow direction and flow velocity are changed, so as to offset the steam flow in the mainstream direction in part of the steam seal structure, and passively reduce the steam flow through the steam seal structure.

[0051] The blade tip steam seal, partition steam seal, bridge steam seal, shaft seal structure, etc. can all be set with unique blade components according to the axial velocity, circumferential velocity, local pressure and temperature of the specific steam flow. The circumferential velocity of the steam flowing through the steam seal structure and the rotation of the seal groove can be used to reduce or block the steam flow through the steam seal body, thereby making full use of the circumferential velocity of the steam in the steam seal structure and reducing the loss of mechanical energy.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A sealing structure based on circumferential relative velocity, comprising: Sealing head: the sealing head is annular, and the inner circumference of the sealing head is formed with protruding annular sealing teeth; Sealing body: The sealing body is annular, and a concave annular sealing groove is formed on the outer circumference of the sealing body. When the sealing head and the sealing body are matched, the sealing head is coaxially sleeved on the outside of the sealing body, and the sealing teeth of the sealing head are inserted into the sealing grooves of the sealing body. There are multiple sealing teeth of the sealing head and multiple sealing grooves of the sealing body, and each sealing tooth of the sealing head is inserted into a sealing groove of the sealing body. It is characterized in that: the sealing structure also includes a blade-shaped component, which includes a plurality of blade-shaped first concave surfaces arranged on the end face of the windward side of the head, and a plurality of second concave surfaces arranged on the windward side of the sealing teeth of the head, the plurality of first concave surfaces are evenly distributed around the end face of the head, and the plurality of second concave surfaces are evenly distributed around the side face of the sealing teeth of the head.

2. The sealing structure based on circumferential relative velocity according to claim 1, characterized in that: The sealing structure is a steam seal structure, a shaft seal structure, a water seal structure and an oil seal structure.

3. The sealing structure based on circumferential relative velocity according to claim 1, characterized in that: The sealing structure is a steam seal structure and a shaft seal structure in a steam turbine.

4. The sealing structure based on circumferential relative velocity according to claim 2 or 3, characterized in that: The steam seal structure includes a blade tip steam seal, a bridge steam seal and a partition steam seal.

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