Steam turbine intermediate pressure cylinder front shaft seal body and shaft end sealing structure including the shaft seal body

Abstract

This utility model discloses a front shaft seal body for a steam turbine intermediate-pressure cylinder and a shaft end sealing structure including the shaft seal body. The front shaft seal body for the steam turbine intermediate-pressure cylinder includes a shaft seal body and an L-shaped annular sealing key. The front end of the shaft seal body has an integrally formed forward-bent section. The front shaft end sealing structure for the steam turbine intermediate-pressure cylinder includes an end-hand steam seal body and a front shaft seal body. Steam seal blocks are embedded in the inner ring of the end-hand steam seal body and in the steam seal block mounting groove of each ring. An SSR chamber is formed between the bent section, the shaft seal body, and the rotor shaft, and a CF chamber is formed between the end-hand steam seal body, the bent section, the rotor shaft, and the cylinder body. Advantages: Compared with the original single SSR chamber, this utility model sets two independent chambers, the SSR chamber and the CF chamber, which effectively reduces the pressure on the end-hand steam seal body, significantly reduces steam leakage, and breaks through the leakage bottleneck of the traditional single-chamber design.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine equipment technology, and in particular to the front shaft seal body of the intermediate 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 unit manufactured by Dongfang Turbine Works. It adopts a three-cylinder, two-exhaust structure. The intermediate-pressure cylinder front shaft seal (hereinafter referred to as the No. 3 shaft seal) is made of conventional high-temperature resistant alloy. The sealing structure is a split upper and lower structure, with a planar contact seal on the split surface, secured by bolts. Figure 1 As shown, the shaft seal body 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 6 between the cylinder body (steam turbine outer cylinder body 5), the end handle steam seal body 3 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. The end handle steam seal body is prone to deformation and leakage when it is under high temperature for a long time. At the same time, if the shaft seal body mating surface deforms 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 body and the shaft seal body deform asynchronously, resulting in an increase in the mating surface gap.

[0003] Since its commissioning, the No. 3 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) increasing the size of the bolts on the split face from M20 to M27 to increase the sealing preload; (2) adding a sealing key and pressure relief groove to the split face of the shaft seal to try to reduce steam leakage through mechanical structure; and (3) performing sealing welding on the vertical flange face and the split face 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 front shaft seal of the intermediate pressure cylinder of a steam turbine and a shaft end sealing structure including the shaft seal, which can effectively reduce steam leakage.

[0007] This utility model is implemented by the following technical solution: a front shaft seal body for a steam turbine intermediate pressure cylinder, comprising a shaft seal body with a two-part structure connected by bolts, wherein the inner wall of the shaft seal body has four steam seal block mounting grooves; characterized in that it further comprises an L-shaped annular sealing key; the front end of the shaft seal body is integrally formed with a bent portion that bends forward, and the inner wall of the bend portion has a steam seal block mounting groove; the outer wall of the shaft seal body is integrally formed with a first sealing ring and a second sealing ring from left to right; a slot is provided on the side wall of the first sealing ring, and the horizontal section of the annular sealing key is inserted into the slot; an exhaust hole is provided on the side wall of the bent portion.

[0008] The front shaft end sealing structure of the intermediate pressure cylinder of a steam turbine includes an end-hand steam seal body and a front shaft seal body. Steam seal blocks are embedded in the inner ring of the end-hand steam seal body and in the steam seal block mounting groove of each ring. The annular sealing key on the first sealing ring and the top edge of the second 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 bent part, the shaft seal body and the rotor shaft, and a CF chamber is formed between the end-hand steam seal body, the bent part, 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.

[0011] This invention achieves efficient leak prevention by reconstructing the sealing interface between the shaft seal body and the cylinder block, as well as the pressure distribution in the chamber. It prevents steam from carrying water vapor and dust into the high and medium pressure bearing box, avoids corrosion or jamming of the sliding pin system, ensures smooth thermal expansion during turbine start-up and shutdown, and reduces the risk of abnormal vibration. At the same time, it reduces heat consumption rate and improves unit operating efficiency. 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 front shaft seal of the intermediate pressure cylinder described in the background art.

[0014] Figure 2 This is a schematic diagram of the structure of the front shaft seal of the intermediate pressure cylinder described in this utility model.

[0015] Figure 3 This is a schematic diagram of the sealing structure at the front shaft end of the intermediate pressure cylinder 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 sealing ring 1.2, second sealing ring 1.3, slot 1.4, exhaust hole 1.5, bending part 1.6, 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 2As shown, this embodiment provides a front shaft seal body for a steam turbine intermediate pressure cylinder, which includes an L-shaped annular sealing key 2 and a two-part shaft seal body 1 connected by bolts. The inner wall of the shaft seal body 1 is provided with four steam seal block mounting grooves 1.1. The front end of the shaft seal body 1 is integrally formed with a forward-bent and tapered section 1.6. The inner wall of the front end of the bent section 1.6 is provided with a steam seal block mounting groove 1.1. The steam seal block mounting groove 1.1 is used to install steam seal blocks 4, and steam seal teeth 4.1 are provided on the steam seal blocks 4.

[0020] The outer wall of the shaft seal body 1 is integrally formed from left to right with a first sealing ring 1.2 and a second sealing ring 1.3; a groove 1.4 is provided on the side wall of the first sealing ring 1.2, and the horizontal section of the annular sealing key 2 is inserted into the groove 1.4; an exhaust hole 1.5 is provided on the side wall of the bent part 1.6.

[0021] Example 2: As Figure 3 As shown, the front shaft end sealing structure of the intermediate pressure cylinder of the steam turbine includes an end-handle steam seal body 3 and a front shaft seal body as in Embodiment 1. Steam seal blocks 4 are embedded in the inner ring of the end-handle steam seal body 3 and in each ring of the 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 block 4 are in contact with the rotor shaft 8. The top edge of the vertical section of the annular sealing key 2 on the first sealing ring 1.2 and the top edge of the second sealing ring 1.3 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 bent part 1.6, the shaft seal body 1 and the rotor shaft 8, and a CF chamber 7 is formed between the end-handle steam seal body 3, the bent part 1.6, the rotor shaft 8 and the cylinder body 5.

[0022] 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, the cylinder body 5 has an air hole that connects to SSR chamber 6 through exhaust port 1.5. SSR chamber 6 maintains the original extraction pressure. CF chamber 7 is connected to the inlet of the shaft fan. Steam flows from right to left, and steam distribution and pressure grading are achieved through the two chambers. The shaft seal body 1 forms a seal with the inner wall of cylinder body 5 through an L-shaped annular sealing key 2, effectively 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.

[0023] 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.

[0024] 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.

[0025] 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 front shaft seal body of an intermediate pressure cylinder in a steam turbine, comprising a shaft seal body of a two-part structure connected by bolts, and four rows of seal block mounting grooves are formed on the inner wall of the shaft seal body; characterized in that, It also includes an L-shaped annular sealing key; The front end of the shaft seal body is integrally formed with a bent part that bends forward and closes out. A ring of steam seal block mounting grooves is formed on the inner wall of the front end of the bent part. The outer wall of the shaft seal body is integrally formed with a first sealing ring and a second sealing ring from left to right; a groove is provided on the side wall of the first sealing ring, and the horizontal section of the annular sealing key is inserted into the groove; Vent holes are provided on the side wall of the bent section.

2. A seal structure for the front shaft end of an intermediate pressure cylinder of a steam turbine, characterized by It includes an end handle steam seal body and a front shaft seal body as described in claim 1, wherein a steam seal block is embedded in the inner ring of the end handle steam seal body and in each ring of the steam seal block mounting groove; the annular sealing key on the first sealing ring and the top edge of the second 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 bent portion, the shaft seal body, and the rotor shaft, and a CF chamber is formed between the end-cap steam seal body, the bent portion, the rotor shaft, and the cylinder block.

Images