Turbine high-pressure cylinder rear shaft seal body and shaft end sealing structure comprising same

Abstract

The utility model discloses a steam turbine high pressure cylinder rear shaft seal body and contain the shaft seal body's axle end seal structure, wherein, steam turbine high pressure cylinder rear shaft seal body includes the shaft seal main part, the annular seal key of section is L type, steam turbine high pressure cylinder rear axle end seal structure includes end take steam seal body, and rear shaft seal body, and the inner wall of end take steam seal body, and every circle steam seal block installation groove all have inserted steam seal block, form SSR chamber between second compartment and steam cylinder body, and form CF chamber between end take steam seal body, shaft seal main part, rotor axle and steam cylinder body. Advantage: the utility model sets up two independent chambers of SSR chamber and CF chamber, effectively reduces the pressure that end take steam seal body suffered, and steam leakage amount is reduced greatly, breaks through the steam leakage bottleneck of traditional single chamber design, and L type seal's metal face contact is matched with steam cylinder body seal groove, can adapt to steam cylinder body thermal deformation, maintains the stability of sealed clearance, avoids the clearance increase due to deformation.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine equipment technology, and in particular to the rear shaft seal body of the high-pressure cylinder of a steam turbine and the shaft end sealing structure including the shaft seal body. Background Technology

[0002] The turbine of Unit 9 is an NZK660-28 / 600 / 620 ultra-supercritical turbine manufactured by Dongfang Turbine Works. It adopts a three-cylinder, two-exhaust structure. The high-pressure cylinder rear shaft seal (hereinafter referred to as the No. 2 shaft seal) is made of ZG15Cr1Mo1, and its sealing structure is a split upper and lower structure. The middle split surface uses a flat contact seal and is fastened with bolts. Figure 1 As shown, the shaft seal body 1 has four rings of steam seal blocks 4 inside. The steam seal teeth 4.1 on the steam seal blocks cooperate with the rotor shaft 8 to form a pressure reducing device. There is an SSR chamber body 6 between the cylinder block (turbine outer cylinder block 5) and the shaft seal body 1. The steam volume in the chamber is large, and the high-pressure steam directly acts on the end handle steam seal body 3. The end handle steam seal body is prone to deformation and leakage due to long-term exposure to high temperature. At the same time, if the shaft seal body mating surface is deformed or the gap exceeds the standard, the SSR chamber is connected to the outside, and the extraction system cannot completely suppress steam leakage. The original shaft seal body structure did not consider the thermal expansion difference under ultra-supercritical conditions. During operation, the cylinder block and shaft seal body deform asynchronously, resulting in an increase in the mating surface gap. In addition, the bolt spacing at the split surface of shaft seal body No. 2 is too large, resulting in uneven distribution of sealing force. The split surface is prone to opening. For example, during the maintenance in 2019, it was found that the maximum gap at the split surface of shaft seal body No. 2 reached 1.30mm, and steam leaked directly from the gap.

[0003] Since its commissioning, the No. 2 shaft seal of the steam turbine has been experiencing steam leakage, and the problem has even worsened. To address the steam leakage issue, modifications were made to the shaft seal, including (1) upgrading the material to ZG1Cr10MoNiVNbN to improve its high-temperature resistance and deformation resistance; (2) increasing the size of the split bolts from M20 to M27 to increase the sealing preload; (3) adding a sealing key and pressure relief groove to the split surface of the shaft seal to try to reduce steam leakage through mechanical structure; and (4) performing sealing welding on the vertical flange face and the split surface of the shaft seal where the gap exceeds the standard to try to fill the leakage channel.

[0004] However, even after implementing the above modifications, the results were still unsatisfactory. Temporary shielding, fan cooling, and wrapping the bearing vibration test points with insulation cotton were still required on-site to mitigate steam leakage. These measures did not fundamentally solve the problem and could mask equipment malfunctions. Long-term steam leakage from the shaft seals could cause the sliding pin system of the intermediate and high-pressure bearing boxes to become stuck, potentially leading to major malfunctions such as abnormal turbine vibration and impeded thermal expansion. If steam leakage leads to a shutdown for maintenance, the losses from a single unit shutdown would be enormous, and long-term steam leakage would increase the heat rate and energy consumption.

[0005] In summary, existing technologies, due to multiple limitations in structural design, material processing, and system configuration, cannot solve the steam leakage problem of shaft seals in ultra-supercritical steam turbines. A technological breakthrough is urgently needed through innovative structural optimization. Utility Model Content

[0006] The purpose of this utility model is to provide a turbine high-pressure cylinder rear shaft seal body and a shaft end sealing structure including the shaft seal body that can effectively reduce steam leakage.

[0007] This utility model is implemented by the following technical solution: a rear shaft seal body of a high-pressure cylinder of a steam turbine, comprising a shaft seal body with a two-part structure connected by bolts; it also includes an L-shaped annular sealing key; the inner wall of the shaft seal body is provided with five steam seal block mounting grooves, wherein the inner wall of the shaft seal body between the third and fourth steam seal block mounting grooves from left to right is provided with a first exhaust groove, and the inner wall of the shaft seal body between the fourth and fifth steam seal block mounting grooves is provided with a second exhaust groove; the outer wall of the shaft seal body is integrally formed with a first sealing ring, a second sealing ring, and a third sealing ring from left to right; slots are provided on the side walls of the second and third sealing rings, and the horizontal section of the annular sealing key is inserted into the corresponding slot; a first compartment is formed between the first and second sealing rings, and a second compartment is formed between the second and third sealing rings; the first exhaust groove and the first compartment, and the second exhaust groove and the second compartment are connected through exhaust holes.

[0008] The high-pressure cylinder rear shaft end sealing structure of a steam turbine includes an end-hand steam seal body and a rear shaft seal body. Steam seal blocks are embedded in the inner wall of the end-hand steam seal body and in the mounting grooves of each steam seal block. The top of the first sealing ring, the annular sealing key on the second sealing ring, the top edge of the third sealing ring, and the annular sealing key on the third sealing ring are respectively inserted into the corresponding sealing grooves on the inner wall of the cylinder body. An SSR chamber is formed between the second compartment and the cylinder body, and a CF chamber is formed between the end-hand steam seal body, the shaft seal body, the rotor shaft, and the cylinder body.

[0009] Advantages of this invention: Compared with the original single SSR chamber, this invention sets up two independent chambers, the SSR chamber and the CF chamber, forming a pressure classification of "high-pressure extraction chamber - low-pressure buffer chamber", which effectively reduces the pressure on the end-hand steam seal body, significantly reduces steam leakage, and breaks through the steam leakage bottleneck of the traditional single-chamber design.

[0010] The metal-to-metal contact of the L-shaped seal with the cylinder block sealing groove can adapt to the thermal deformation of the cylinder block, maintain the stability of the sealing gap, and avoid the gap increase caused by deformation, thus solving the defect of "welded seals cannot adapt to dynamic deformation" in the existing technology.

[0011] By reconstructing the sealing interface between the shaft seal body and the cylinder block, improving the bolt arrangement and chamber pressure distribution, efficient leakage prevention is achieved, preventing steam from carrying water vapor and dust into the high and medium pressure bearing box, avoiding rust or jamming of the sliding pin system, ensuring smooth thermal expansion during turbine start-up and shutdown, and reducing the risk of abnormal vibration; at the same time, the heat consumption rate is reduced and the unit operating efficiency is improved. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the installation structure of the high-pressure cylinder rear shaft seal body described in the background art.

[0014] Figure 2 This is a schematic diagram of a quarter section of the rear shaft seal of the high-pressure cylinder.

[0015] Figure 3 This is a schematic diagram illustrating the installation and use of the high-pressure cylinder rear shaft end sealing structure described in this utility model.

[0016] The components in the attached diagram are labeled as follows: Shaft seal body 1, steam seal block mounting groove 1.1, first exhaust groove 1.2, second exhaust groove 1.3, first sealing ring 1.4, second sealing ring 1.5, third sealing ring 1.6, slot 1.7, first compartment 1.8, second compartment 1.9, exhaust hole 1.10, annular sealing key 2, end handle steam seal body 3, steam seal block 4, steam seal tooth 4.1, cylinder body 5, sealing groove 5.1, SSR chamber 6, CF chamber 7, rotor shaft 8. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and 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 this utility model.

[0019] Example 1: As Figure 2 As shown, this embodiment provides a rear shaft seal body for a high-pressure cylinder of a steam turbine, which includes an annular sealing key 2 with an L-shaped cross-section and a shaft seal body 1 with a two-part structure connected by bolts.

[0020] The inner wall of the shaft seal body 1 has five rings of steam seal block mounting grooves 1.1 for mounting steam seal blocks 4, and the steam seal blocks 4 are provided with steam seal teeth 4.1; wherein, the inner wall of the shaft seal body 1 between the third ring of steam seal block mounting grooves 1.1 and the fourth ring of steam seal block mounting grooves 1.1 from left to right has a first exhaust groove 1.2, and the inner wall of the shaft seal body 1 between the fourth ring of steam seal block mounting grooves 1.1 and the fifth ring of steam seal block mounting grooves 1.1 has a second exhaust groove 1.3.

[0021] The outer wall of the shaft seal body 1 is integrally formed from left to right with a first sealing ring 1.4, a second sealing ring 1.5 and a third sealing ring 1.6; the side walls of the second sealing ring 1.5 and the third sealing ring 1.6 are both provided with slots 1.7, the horizontal section of one of the annular sealing keys 2 is engaged in the slot 1.7 of the second sealing ring 1.5, and the horizontal section of the other annular sealing key 2 is engaged in the slot 1.7 of the third sealing ring 1.6.

[0022] A first compartment 1.8 is formed between the first sealing ring 1.4 and the second sealing ring 1.5, and a second compartment 1.9 is formed between the second sealing ring 1.5 and the third sealing ring 1.6. The shaft seal body 1 is provided with an exhaust hole 1.10 that connects the first exhaust groove 1.2 with the first compartment 1.8 and the second exhaust groove 1.3 with the second compartment 1.9. Steam in the first exhaust groove 1.2 is discharged into the first compartment 1.8 through the corresponding exhaust hole 1.10, and steam in the second exhaust groove 1.3 is discharged into the second compartment 1.9 through the corresponding exhaust hole 1.10.

[0023] Example 2: Figure 3As shown, the rear shaft end sealing structure of the high-pressure cylinder of the steam turbine includes an end-hand steam seal body 3 and a rear shaft seal body as in Embodiment 1. A ring of steam seal blocks 4 is embedded in the inner wall of the end-hand steam seal body 3, and a ring of steam seal blocks 4 is also embedded in each ring of steam seal block mounting groove 1.1. During installation and use, the shaft seal body 1 is fitted onto the rotor shaft 8 of the steam turbine, and the steam seal teeth 4.1 on the steam seal blocks 4 are in contact with the rotor shaft 8. The top edge of the first sealing ring 1.4, the annular sealing key 2 on the second sealing ring 1.5, the edge of the third sealing ring 1.6, and the annular sealing key 2 on the third sealing ring 1.6 are respectively inserted into the corresponding sealing groove 5.1 on the inner wall of the cylinder body 5, with a gap. An SSR chamber 6 is formed between the second compartment 1.9 and the cylinder body 5, and a CF chamber 7 is formed between the end-hand steam seal body 3, the shaft seal body 1, the rotor shaft 8, and the cylinder body 5.

[0024] Compared to the single SSR chamber 6 in the prior art, this embodiment provides two independent chambers, SSR chamber 6 and CF chamber 7. In actual operation, SSR chamber 6 maintains the original extraction pressure, while CF chamber 7 is connected to the shaft fan inlet. Steam flows from left to right, achieving steam distribution and pressure grading through the two chambers. The shaft seal body 1 forms a seal with the inner wall of the cylinder body 5 through the L-shaped annular sealing key 2, effectively reducing the amount of steam entering SSR chamber 6 and CF chamber 7, especially reducing the amount of steam entering CF chamber 7, effectively reducing the pressure on the end-hand steam seal body 3, and significantly reducing steam leakage. Furthermore, the design of the separated chambers changes the single extraction chamber into a graded pressure chamber, forming a "pressure buffer zone" to block the steam leakage path.

[0025] The bolted two-part structure shaft seal body 1 and the two-part structure end handle steam seal body 3, by increasing the number of bolts, improve the preload of the two-part structure, suppress the opening deformation of the middle part, distribute the axial force of the bolts evenly, reduce the increase in the gap of the middle part of the end handle steam seal body 3 caused by the thermal expansion of the cylinder body 5, and block the steam leakage channel from the source.

[0026] The L-shaped annular seal increases the number and area of ​​sealing surfaces. At the same time, the L-shaped annular seal key 2 utilizes the plastic deformation of metal to achieve dynamic contact with the shaft seal body 1, taking advantage of the thermal expansion difference between the cylinder block 5 and the shaft seal body 1, effectively reducing the amount of steam leaking into the CF chamber 7.

[0027] In actual operation, pressure gauges are installed in the corresponding chambers. The pressure gauge data is used to determine whether the pressure distribution in SSR chamber 6 and CF chamber 7 is abnormal, so as to accurately locate and warn of steam leakage problems.

[0028] The addition of bolts to strengthen mechanical tightening, the optimization of the sealing interface with L-shaped seals, and the use of pressure gauges to monitor operating status, work together to completely eliminate steam leakage problems.

[0029] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A rear shaft seal body for a high-pressure cylinder of a steam turbine, comprising a shaft seal body with two separate structures connected by bolts; characterized in that, It also includes an annular sealing key with an L-shaped cross-section; The inner wall of the shaft seal body is provided with five rings of steam seal block mounting grooves. Among them, the inner wall of the shaft seal body between the third ring of steam seal block mounting groove and the fourth ring of steam seal block mounting groove from left to right is provided with a first exhaust groove, and the inner wall of the shaft seal body between the fourth ring of steam seal block mounting groove and the fifth ring of steam seal block mounting groove is provided with a second exhaust groove. The outer wall of the shaft seal body is integrally formed from left to right with a first sealing ring, a second sealing ring and a third sealing ring; the side walls of the second sealing ring and the third sealing ring are both provided with slots, and the horizontal section of the annular sealing key is inserted into the corresponding slot; A first compartment is formed between the first sealing ring and the second sealing ring, and a second compartment is formed between the second sealing ring and the third sealing ring; the first exhaust groove and the first compartment, and the second exhaust groove and the second compartment are all connected through exhaust holes.

2. A sealing structure at the rear shaft end of a high-pressure cylinder for a steam turbine, characterized in that, It includes an end-handle steam seal body and a rear shaft seal body as described in claim 1, wherein a steam seal block is embedded in the inner wall of the end-handle steam seal body and in each of the steam seal block mounting grooves; the top of the first sealing ring, the annular sealing key on the second sealing ring, the edge of the third sealing ring, and the annular sealing key on the third sealing ring are respectively inserted into the corresponding sealing grooves on the inner wall of the cylinder body; The second compartment forms an SSR chamber between itself and the cylinder block, and the end valve steam seal body, shaft seal body, rotor shaft, and cylinder block form a CF chamber.

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