A segmented bridge pass seal, method, and steam turbine with reduced steam leakage

Abstract

This invention provides a segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage, applicable to steam turbines. The steam turbine includes an intermediate-high pressure outer cylinder, an integral high pressure inner cylinder, an intermediate pressure inner cylinder, a segmented cross-bridge steam seal, and an intermediate-high pressure rotor. The integral high pressure inner cylinder and intermediate pressure inner cylinder are both located within the intermediate-high pressure outer cylinder, and the segmented cross-bridge steam seal is located between the integral high pressure inner cylinder and the intermediate pressure inner cylinder. The segmented cross-bridge steam seal has several cross-bridge steam seal outlet rectifier chambers, and the integral high pressure inner cylinder includes several high pressure cylinder extraction chambers. The several cross-bridge steam seal outlet rectifier chambers are respectively connected to the several high pressure cylinder extraction chambers. In this invention, the main steam leaking from the segmented cross-bridge steam seal enters the integral high pressure inner cylinder through the make-up steam chamber, realizing the reuse of the main steam leaking from the segmented cross-bridge steam seal. This solves the problems of large steam leakage from the cross-bridge steam seal, waste of heat energy in high-quality steam, and high overall heat consumption rate of the turbine.

Description

Technical Field

[0001] This invention relates to the field of high-pressure combined cylinder steam turbine technology, and in particular to a segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage. Background Technology

[0002] For steam turbine units with combined high- and intermediate-pressure cylinders, a corresponding balancing piston seal (i.e., a "bridge seal") needs to be installed between the high-pressure cylinder inlet and the intermediate-pressure cylinder inlet to balance the thrust between the high-pressure and intermediate-pressure flow. The sealing structure in this area mostly adopts a non-contact seal—the labyrinth seal. This seal has advantages such as simple structure, stable performance, easy installation, and low cost, and is therefore widely used in turbomachinery such as steam turbines, gas turbines, compressors, and blowers.

[0003] The steam flow system diagram of the existing technology using an integral bridge steam seal is shown below. Figure 1 As shown, specifically:

[0004] Step 1: The main steam flows out from the steam generator (usually a boiler), and after passing through the main steam valve 1, it is divided into two parallel paths. One path flows through the main control valve 2 and enters the high-pressure cylinder inlet chamber 200 (defined as: steam 008 after the main control valve). After entering the high-pressure cylinder inlet chamber 200, the steam 008 after the main control valve is divided into two paths. One path does work on the expansion channel of the moving and stationary blades on the high-pressure rotor 20 (defined as: steam flow through the integral high-pressure inner cylinder 340). After the integral high-pressure inner cylinder steam flow 340 completes its expansion, it enters the high-pressure cylinder exhaust chamber 202. Another path enters the integral bridge steam seal 8 (defined as: steam 300 leaking through the integral bridge steam seal). Part of the steam 300 leaking through the integral bridge steam seal enters the high-pressure cylinder exhaust chamber 202 (defined as: steam leakage 011 from the bridge steam seal outlet to the high-pressure cylinder exhaust chamber), and the other part enters the intermediate-pressure steam inlet side balance piston steam seal ring 9 (defined as: steam 320 leaking through the intermediate-pressure steam inlet side balance piston steam seal ring).

[0005] Step 2: The other path after the main steam valve 1 flows through the make-up steam valve 5 (defined as: steam 009 after the make-up steam valve). The steam 009 after the make-up steam valve enters the make-up steam chamber 205 through the steam inlet pipe 26 of the make-up steam valve, and is then collected and enters the integral high-pressure inner cylinder steam flow 340. After expansion is completed, it enters the high-pressure cylinder exhaust chamber 202.

[0006] Step 3: The main steam in the high-pressure cylinder exhaust chamber 202 enters the reheater 11 (defined as: steam 012 from the high-pressure cylinder exhaust chamber to the reheater), and is reheated to become high-quality reheated main steam. Then, it enters the intermediate-pressure cylinder inlet chamber 201 (defined as: steam 007 after the reheating main control valve) through the reheating main steam valve 3 and the reheating main control valve 4. The steam 007 after the reheating main control valve enters the intermediate-pressure cylinder inlet chamber 201 and expands to drive the intermediate-pressure rotor 20 to rotate (defined as: intermediate-pressure inner cylinder steam flow 330). After the intermediate-pressure inner cylinder steam flow 330 expands, it enters the intermediate-pressure cylinder exhaust chamber 204, and finally passes through the intermediate-pressure cylinder extraction chamber 203 or the intermediate-pressure cylinder exhaust chamber 204 for subsequent processes. (The reheated main steam discharged through the intermediate pressure cylinder extraction chamber 203 is defined as: the first reheat extraction of the intermediate pressure cylinder 014; the reheated main steam discharged through the intermediate pressure cylinder exhaust chamber 204 is defined as: the steam in the intermediate pressure cylinder exhaust chamber 015). The subsequent process can be to continue to enter the low-pressure inner cylinder for expansion and work.

[0007] To improve the overall cycle thermal efficiency of the generator set, the steam inlet parameters (pressure and temperature) of the high-pressure and intermediate-pressure cylinders of the steam turbine have been upgraded from subcritical and supercritical to ultra-supercritical parameters. However, due to the high-temperature operating environment, the components in the inlet area exhibit significant radial and axial absolute thermal expansion and differential expansion between moving and stationary parts. This results in large hot-state operating clearances between moving and stationary parts, and the pressure ratio between the inlet and outlet sides of the bridge steam seal is much greater than in other areas such as the cylinder end shaft seal area. Ultimately, this leads to relatively large steam leakage in the bridge steam seal area, reaching 2-3% of the main steam flow. During actual operation, the actual steam leakage of the bridge steam seal can exceed the design value by 3-4 times, and a 1% leakage of the main steam flow will increase the overall heat rate of the unit by about 0.3%. Furthermore, after long-term operation in a high-temperature environment, the components in this area also experience significant high-temperature creep strain, leading to significant misalignment between moving and stationary parts. During overhaul and maintenance of the unit, varying degrees of wear on the steam seal teeth in this area are frequently observed. Reducing steam leakage at the bridge seal of a high-pressure and intermediate-pressure combined cylinder turbine unit has become an important issue for unit retrofitting and new unit development.

[0008] Currently, improvements to the technology of the bridge steam seal area mainly focus on structural optimization of the seal ring in this area. For example, in existing technologies, in addition to the commonly used non-contact labyrinth seal, there are also contact seals and honeycomb seals. Contact seals theoretically achieve gapless operation and good sealing performance, with contact teeth enabling automatic tracking and compensation. However, they are prone to causing unit vibration, making startup difficult, and causing some wear on the main shaft. After high-temperature creep deformation, the seal gap widens, leading to increased leakage. Compared to non-contact labyrinth seals, honeycomb seals eliminate the short seal teeth and effectively reduce steam leakage using a honeycomb strip. However, the honeycomb strip is prone to scale buildup, making cleaning difficult and leading to loss of sealing function. It also has a short service life, and the large area of ​​the honeycomb strip, if improperly set, can easily cause dynamic and static friction. Due to the drawbacks of contact and honeycomb seals, most high- and medium-pressure combined turbine units still use non-contact sealing seals.

[0009] In addition, the prior art application number CN202110227226.5 proposes a structure to reduce the leakage of steam seals across bridges. The structure guides the leakage steam through an axial flow rotating steam seal to form a high-pressure vortex to block the leakage steam from pouring to the low-pressure side. The axial flow steam seal teeth rotate with the rotor and continuously and periodically squeeze the leakage steam in the steam seal gap, thereby forming a high-pressure vortex and steam curtain to block the leakage steam from leaking out.

[0010] The prior art application CN202221210737.2 discloses a bridge steam seal for a steam power generation device, including an annular steam seal body and a plurality of annular ribs disposed within the annular steam seal body. The plurality of annular ribs are spaced apart. A first annular groove is formed on the inner wall of the annular steam seal body. The groove extends circumferentially along the annular steam seal body. The annular ribs are provided between the groove opening and the inlet of the annular steam seal body and between the groove opening and the outlet of the annular steam seal body. The bridge steam seal is an integral structure.

[0011] In summary, existing methods for reducing steam leakage from bridge steam seals primarily involve optimizing the structure of the sealing teeth on the sealing ring. Essentially, this is based on the principle that the labyrinth seal applies pressure differential resistance to the flow of leaking steam, dissipating the pressure differential driving the steam leakage into kinetic energy, which is ultimately dissipated into heat energy, thus reducing steam leakage. Compared to conventional non-contact labyrinth sealing ring structures, the structural solutions proposed in the two patents mentioned above are relatively complex, have very high machining costs, and face significant challenges in large-scale engineering applications. Therefore, there is potential for further optimization of the technical solutions for reducing steam leakage from bridge steam seals. Summary of the Invention

[0012] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage. The main steam leaking through the cross-bridge steam seal is redirected to leak into a certain extraction or makeup steam chamber. By reducing the pressure in stages, the inlet and outlet pressure ratio of the cross-bridge steam seal is reduced, and the amount of main steam leaking directly through the integral cross-bridge steam seal to the high-pressure cylinder exhaust chamber is reduced. This solves the problems of large steam leakage from the cross-bridge steam seal, waste of heat energy in high-quality steam, and high overall heat consumption rate in the prior art.

[0013] To achieve the above and other related objectives, this invention provides a segmented cross-bridge steam seal for reducing steam leakage, applied in a steam turbine. The steam turbine includes an intermediate-high pressure outer cylinder, an integral high-pressure inner cylinder, an intermediate-pressure inner cylinder, a segmented cross-bridge steam seal, and an intermediate-high pressure rotor. The integral high-pressure inner cylinder and the intermediate-pressure inner cylinder are both located within the intermediate-high pressure outer cylinder, and the segmented cross-bridge steam seal is located between the integral high-pressure inner cylinder and the intermediate-pressure inner cylinder. The segmented cross-bridge steam seal has several cross-bridge steam seal outlet rectifier chambers. The integral high-pressure inner cylinder includes several high-pressure cylinder extraction chambers and several steam leakage pipes. The several cross-bridge steam seal outlet rectifier chambers are respectively connected to the several high-pressure cylinder extraction chambers through the steam leakage pipes. The main steam enters the integral high-pressure inner cylinder and is divided into two paths. One path of main steam expands and performs work in the integral high-pressure inner cylinder, driving the intermediate-high pressure rotor to rotate. The other path of main steam enters the segmented cross-bridge steam seal and, through the several cross-bridge steam seal outlet rectifier chambers, enters the several high-pressure cylinder extraction chambers for recycling.

[0014] Preferably, the integral high-pressure inner cylinder further includes a steam replenishment chamber, and the high- and medium-pressure outer cylinder is also provided with a steam replenishment valve inlet pipe. A steam replenishment valve is provided on the steam replenishment valve inlet pipe, and the steam replenishment valve inlet pipe is connected to the steam replenishment chamber; any of the bridge steam seal outlet rectifier chambers is connected to the steam replenishment chamber through a steam leakage pipe.

[0015] Preferably, the segmented cross-bridge steam seal includes a two-section cross-bridge steam seal, the number of the cross-bridge steam seal outlet rectifier cavity is one, and the cross-bridge steam seal outlet rectifier cavity is connected to the extraction steam cavity of any high-pressure cylinder; or the cross-bridge steam seal outlet rectifier cavity is connected to the make-up steam cavity.

[0016] Preferably, the number of the steam leakage pipes is at least one, and the steam leakage pipes connect the rectifier cavity of the bridge steam seal outlet to any high-pressure cylinder extraction cavity, or the steam leakage pipes connect the rectifier cavity of the bridge steam seal outlet to the make-up steam cavity.

[0017] Preferably, the segmented cross-bridge steam seal includes a three-section cross-bridge steam seal, and the number of the cross-bridge steam seal outlet rectifier cavities is two, and the two cross-bridge steam seal outlet rectifier cavities are connected to any two high-pressure cylinder extraction steam cavities; or the two cross-bridge steam seal outlet rectifier cavities are respectively connected to the make-up steam cavity and any one of the high-pressure cylinder extraction steam cavities.

[0018] Preferably, the number of the steam leakage pipes is at least two, and the two bridge steam seal outlet rectifier cavities are connected to any two high-pressure cylinder extraction cavities, or the two bridge steam seal outlet rectifier cavities are respectively connected to the make-up steam cavity and any one high-pressure cylinder extraction cavity through the steam leakage pipes.

[0019] To achieve the above or other objectives, the present invention also discloses a method for reducing steam leakage in a segmented bridge steam seal, the steps of which are as follows:

[0020] S1: Determine the pressure data and pressure ratio of the integral high-pressure inner cylinder inlet pressure, integral high-pressure inner cylinder exhaust pressure, and intermediate-pressure inner cylinder inlet pressure. Combined with the axial arrangement space at the segmented bridge steam seal, determine the number of steam seal segments to be divided by the segmented bridge steam seal.

[0021] S2: Based on the steam inlet pressure of the integral high-pressure inner cylinder, the steam outlet pressure of the integral high-pressure inner cylinder, the structural parameters of the steam seal teeth in each steam seal section, and the axial and radial hot operating clearance data of each steam seal section, calculate and evaluate the pressure of the rectifier chamber at the outlet of each bridge steam seal and the corresponding steam leakage of each steam seal section.

[0022] S3: Based on the leakage of each steam seal section, the number of steam leakage pipes, the selected pipe diameter and pipeline layout of the steam leakage pipes, calculate and evaluate the pipeline pressure loss between the rectifier chamber at the outlet of each bridge steam seal and the extraction chamber of the high-pressure cylinder, and meet the following requirements: the pressure of the rectifier chamber at the outlet of each bridge steam seal minus the pipeline pressure loss of the steam leakage pipe is equal to the pressure of the extraction chamber of the high-pressure cylinder at the connection of the steam leakage pipe.

[0023] Preferably, in step S3, if the pressure of the rectifier chamber at the outlet of each bridge steam seal, the pressure loss of the steam leakage pipe, and the pressure of the high-pressure cylinder extraction chamber at the connection of the steam leakage pipe cannot meet the above requirements, the diameter, quantity, and pipeline layout of the steam leakage pipe should be adjusted to regulate the pressure loss of the steam leakage pipe; or the number of steam seal teeth in each steam seal section in step S2 should be adjusted to regulate the pressure of the rectifier chamber at the outlet of each bridge steam seal.

[0024] To achieve the above or other objectives, the present invention also discloses a steam turbine, the steam turbine including the segmented bridge steam seal described above for reducing steam leakage.

[0025] Preferably, the steam turbine further includes a high-pressure cylinder inlet chamber, a high-pressure cylinder outlet chamber, an intermediate-pressure cylinder inlet chamber, and an intermediate-pressure cylinder outlet chamber. Main steam enters the integral high-pressure inner cylinder through the high-pressure cylinder inlet chamber. The main steam expands and performs work within the integral high-pressure inner cylinder, driving the intermediate-pressure rotor to rotate. After completing its expansion and work, the main steam enters the high-pressure cylinder outlet chamber. The main steam in the high-pressure cylinder outlet chamber is heated by a reheater and then enters the intermediate-pressure inner cylinder through the intermediate-pressure cylinder inlet chamber. The reheated main steam expands and performs work within the intermediate-pressure inner cylinder, driving the intermediate-pressure rotor to rotate. After completing its expansion and work within the intermediate-pressure inner cylinder, the reheated main steam enters the intermediate-pressure cylinder outlet chamber and exits the intermediate-pressure inner cylinder.

[0026] Preferably, a high-pressure exhaust-side balance piston steam seal ring is further provided between the high-pressure cylinder exhaust chamber and the intermediate-pressure outer cylinder, and an intermediate-pressure inlet-side balance piston steam seal ring is further provided between the high-pressure cylinder exhaust chamber and the intermediate-pressure inner cylinder. The high-pressure exhaust-side balance piston steam seal ring and the intermediate-pressure outer cylinder form a high-pressure exhaust-side balance piston steam seal ring outlet rectifier chamber, and the high-pressure exhaust-side balance piston steam seal ring outlet rectifier chamber is connected to the intermediate-pressure cylinder exhaust chamber through a balance pipe.

[0027] As described above, the segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage involved in this invention have the following beneficial effects:

[0028] This invention relates to a segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage. The segmented cross-bridge steam seal includes several outlet rectifier chambers, and the integral high-pressure inner cylinder has several high-pressure extraction chambers. This allows the main steam leaking from the segmented cross-bridge steam seal to be reused for heat recovery through the high-pressure extraction chambers. The integral high-pressure inner cylinder may also have a make-up steam chamber, connected to the outlet rectifier chambers. The main steam leaking from the segmented cross-bridge steam seal enters the integral high-pressure inner cylinder through the make-up steam chamber, thus expanding and performing work on the high- and intermediate-pressure rotor. This achieves the reuse of the main steam leaking from the segmented cross-bridge steam seal, solving the problems of large steam leakage, waste of heat energy in high-quality steam, and high overall heat consumption rate in existing technologies. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the steam flow principle when using an integral bridge steam seal in existing technology (including the steam injection chamber).

[0030] Figure 2 This is a schematic diagram illustrating the steam flow principle when a two-stage bridge steam seal is used in this invention.

[0031] Figure 3 This is a cross-sectional view of the high-pressure combined cylinder steam turbine using a two-stage bridge steam seal in this invention;

[0032] Figure 4for Figure 3 Enlarged view of the steam seal at the two-section bridge section;

[0033] Figure 5 A three-dimensional structural diagram of the integral high-pressure inner cylinder when a two-stage bridge steam seal is used;

[0034] Figure 6 This is a schematic diagram illustrating the steam flow principle when a three-section bridge steam seal is used in this invention.

[0035] Figure 7 This is a cross-sectional view of the high-pressure combined cylinder steam turbine using a three-section cross-bridge steam seal in this invention;

[0036] Figure 8 for Figure 7 Enlarged view of the steam seal at the three-section bridge section;

[0037] Figure 9 This is a three-dimensional structural diagram of the integral high-pressure inner cylinder when a three-section bridge steam seal is used;

[0038] Figure 10 This is a schematic diagram illustrating the steam flow principle when using a two-stage bridge steam seal in this invention; (the integral high-pressure inner cylinder does not include the steam injection chamber).

[0039] Figure 11 This is a schematic diagram illustrating the steam flow principle when using a three-section bridge steam seal in this invention; (the integral high-pressure inner cylinder does not include the steam injection chamber).

[0040] Explanation of reference numerals in the attached figures:

[0041]

[0042]

[0043] Detailed Implementation

[0044] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0045] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0046] like Figures 2-11 As shown, this invention provides a segmented cross-bridge steam seal for reducing steam leakage, applied in a steam turbine. The steam turbine includes an intermediate and high-pressure outer cylinder 21, an integral high-pressure inner cylinder 6, an intermediate-pressure inner cylinder 7, a segmented cross-bridge steam seal, and an intermediate and high-pressure rotor 20. The integral high-pressure inner cylinder 6 and the intermediate-pressure inner cylinder 7 are both located within the intermediate and high-pressure outer cylinder 21, and the segmented cross-bridge steam seal is located between the integral high-pressure inner cylinder 6 and the intermediate-pressure inner cylinder 7. The segmented cross-bridge steam seal has several cross-bridge steam seal outlet rectifier chambers. The inner cylinder 6 includes several high-pressure cylinder extraction chambers 206 and several bridge steam seal outlet rectifier chambers, which are respectively connected to several high-pressure cylinder extraction chambers 206. The main steam enters the integral high-pressure inner cylinder 6 and is divided into two paths. One path is used as the integral high-pressure inner cylinder steam flow 340 to expand and do work in the integral high-pressure inner cylinder 6, driving the high- and medium-pressure rotor 20 to rotate. The other path enters the segmented bridge steam seal and enters the several high-pressure cylinder extraction chambers 206 through several bridge steam seal outlet rectifier chambers for recycling.

[0047] The present invention relates to a segmented cross-bridge steam seal for reducing steam leakage. When the main steam introduced into the integral high-pressure inner cylinder 6 enters the segmented cross-bridge steam seal, it will converge in the cross-bridge steam seal outlet rectifier cavity and enter the high-pressure cylinder extraction chamber 206. The high-pressure cylinder extraction chamber 206 recovers and utilizes a certain amount of leaked high-quality steam, solving the problems of large steam leakage, waste of heat energy of high-quality leaked steam, and high turbine heat consumption rate in the prior art.

[0048] Preferred, such as Figure 2 , Figure 3 , Figure 6 , Figure 7As shown, the segmented cross-bridge steam seal for reducing steam leakage involved in this invention is applied in a steam turbine. The steam turbine also includes a high-pressure cylinder inlet chamber 200, a high-pressure cylinder exhaust chamber 202, an intermediate-pressure cylinder inlet chamber 201, and an intermediate-pressure cylinder exhaust chamber 204. A reheater 11 is also provided on the outside of the steam turbine, which is used to heat the steam. The main steam enters the integral high-pressure inner cylinder 6 through the high-pressure cylinder inlet chamber 200. In the integral high-pressure inner cylinder 6, the main steam expands and performs work, forming a steam flow 340 that drives the intermediate and high-pressure rotor 20 to rotate. After the main steam completes its expansion and work, it enters the high-pressure cylinder exhaust chamber 202. The main steam in the high-pressure cylinder exhaust chamber 202 is heated by the reheater 11 and enters the intermediate-pressure inner cylinder 7 through the intermediate-pressure cylinder inlet chamber 201. The reheated main steam expands and performs work in the intermediate-pressure inner cylinder 7, forming a steam flow 330 that drives the intermediate and high-pressure rotor 20 to rotate. After the reheated main steam completes its expansion and work in the intermediate-pressure inner cylinder 7, it enters the intermediate-pressure cylinder exhaust chamber 204 and is discharged from the intermediate-pressure inner cylinder 7. Furthermore, the main steam flow pipeline is also equipped with a main steam valve 1 and a main regulating valve 2. The main steam valve 1 controls the on / off flow of main steam into the turbine, and the main regulating valve 2 controls the flow rate of main steam into the turbine.

[0049] Preferred, such as Figure 3 , Figure 7 As shown, a high-pressure exhaust-side balance piston steam seal ring 10 is provided between the high-pressure cylinder exhaust chamber 202 and the intermediate-pressure outer cylinder 21, and an intermediate-pressure inlet-side balance piston steam seal ring 9 is provided between the high-pressure cylinder exhaust chamber 202 and the intermediate-pressure inner cylinder 7. The cavity between the high-pressure exhaust-side balance piston steam seal ring 10 and the intermediate-pressure outer cylinder 21 is connected to the intermediate-pressure cylinder exhaust chamber 204 through a balance pipe. Furthermore, a left-side internal end steam seal body 22 is provided between the left-side outer wall of the intermediate-pressure outer cylinder 21 and the intermediate-pressure rotor 20, a left-side external end steam seal body 23 is provided between the left-side inner wall of the intermediate-pressure outer cylinder 21 and the intermediate-pressure rotor 20, a right-side internal end steam seal body 24 is provided between the right-side inner wall of the intermediate-pressure outer cylinder 21 and the intermediate-pressure rotor 20, and a right-side external end steam seal body 25 is provided between the right-side outer wall of the intermediate-pressure outer cylinder 21 and the intermediate-pressure rotor 20. This application includes a high-pressure exhaust-side balance piston steam seal ring 10 and a medium-pressure inlet-side balance piston steam seal ring 9 to isolate the integral high-pressure inner cylinder 6 from the medium-pressure inner cylinder 7, preventing main steam from directly entering the medium-pressure inner cylinder 7 from the integral high-pressure inner cylinder 6. A left-side internal end steam seal body 22, a left-side external end steam seal body 23, a right-side internal end steam seal body 24, and a right-side external end steam seal body 25 are provided to isolate the integral high-pressure inner cylinder 6, the medium-pressure inner cylinder 7, the intermediate-high-pressure outer cylinder 21, and the external air, preventing steam leakage from the integral high-pressure inner cylinder 6 and the medium-pressure inner cylinder 7 into the intermediate-high-pressure outer cylinder 21, and preventing steam leakage from the intermediate-high-pressure outer cylinder 21 into the external air, thus preventing heat loss.

[0050] Preferred, such as Figures 3-9 As shown, the integral high-pressure inner cylinder 6 also includes a steam replenishment chamber 205, and any of the bridge steam seal outlet rectifier chambers are also connected to the steam replenishment chamber 205; the high- and medium-pressure outer cylinder 21 is also provided with a steam replenishment valve inlet pipe 26, and a steam replenishment valve 5 is provided on the steam replenishment valve inlet pipe 26, which is connected to the steam replenishment chamber 205; the steam replenishment chamber 205 and the steam replenishment valve 5 are used to replenish the amount of steam in the integral high-pressure inner cylinder 6, ensuring that the steam flow 340 in the integral high-pressure inner cylinder 6 expands and does work.

[0051] Furthermore, the segmented bridge steam seal in this application is divided into a two-section bridge steam seal 80 and a three-section bridge steam seal 800. The integral high-pressure inner cylinder 6 in this application has two structural embodiments: one with a steam replenishment chamber 205 and the other without a steam replenishment chamber 205. Therefore, this application has the following embodiments:

[0052] 1. First embodiment: The segmented bridge steam seal is a two-stage bridge steam seal 80

[0053] like Figures 2-4 , Figure 10 As shown, the segmented bridge steam seal is configured as a two-section bridge steam seal 80, which includes a first bridge steam seal section 100 and a second bridge steam seal section 101. The number of bridge steam seal outlet rectifier chambers is one, defined as the first bridge steam seal outlet rectifier chamber 208. The first bridge steam seal outlet rectifier chamber 208 is located between the outlet of the first bridge steam seal section 100 and the inlet of the second bridge steam seal section 101. The first bridge steam seal outlet rectifier chamber 208 is connected to the make-up steam chamber 205 or any high-pressure cylinder extraction steam chamber 206.

[0054] Furthermore, the first bridge steam seal section 100 consists of five conventional non-contact labyrinth steam seal rings, and the second bridge steam seal section 101 consists of three conventional non-contact labyrinth steam seal rings. In this embodiment, the two-section bridge steam seal 80 rings adopt a "five + three" steam seal ring combination, which can be combined in various ways depending on the pressure at the segmentation point, the steam seal ring structure, and the leakage control target.

[0055] At this point, the integral high-pressure inner cylinder 6 has two configurations: one with a steam injection chamber 205 and the other without. The two configurations will now be analyzed separately:

[0056] 1.1 The integral high-pressure inner cylinder 6 has a steam injection chamber 205.

[0057] like Figure 2 As shown in embodiment 1.1, the steam flow principle in the steam turbine is as follows:

[0058] Step 1: The main steam flows out from the steam generator (usually a boiler), and after passing through the main steam valve 1, it splits into two parallel paths. One path flows through the main regulating valve 2 and enters the high-pressure cylinder inlet chamber 200 (defined as: steam 008 after the main regulating valve). After entering the high-pressure cylinder inlet chamber 200, the steam 008 after the main regulating valve splits into two paths again. One path performs work on the expansion channels of the moving and stationary blades on the high-pressure rotor 20 (defined as: steam flow through the integral high-pressure inner cylinder 340). After the integral high-pressure inner cylinder steam flow 340 expands, it enters the high-pressure cylinder exhaust chamber 202. The other path enters the first bridge steam seal section 100 (defined as: leakage steam 301 flowing through the first bridge steam seal section). Part of the leakage steam 301 flowing through the first bridge steam seal section enters the first bridge steam seal outlet rectifier chamber 208, and the other part enters the second bridge steam seal section 101 (defined as: leakage steam 302 flowing through the second bridge steam seal section).

[0059] Step 2: The other path after the main steam valve 1 flows through the make-up steam valve 5 (defined as: steam 009 after the make-up steam valve). The steam 009 after the make-up steam valve enters the make-up steam chamber 205 through the steam inlet pipe 26 of the make-up steam valve, and is combined with the steam from the first bridge steam seal outlet rectifier chamber 208 to enter the integral high-pressure inner cylinder steam flow 340. After expansion is completed, it enters the high-pressure cylinder exhaust chamber 202.

[0060] Step 3: The leaked steam 302 flowing through the second bridge steam seal section in Step 1 is divided into two parts. One part enters the high-pressure cylinder exhaust chamber 202 (defined as: the leaked steam 011 from the bridge steam seal outlet to the high-pressure cylinder exhaust chamber), and the other part enters the medium-pressure steam inlet side balance piston steam seal ring 9 (defined as: the steam 320 leaking through the medium-pressure steam inlet side balance piston steam seal ring).

[0061] Step 4: The main steam in the high-pressure cylinder exhaust chamber 202 enters the reheater 11 (defined as: steam 012 from the high-pressure cylinder exhaust chamber to the reheater), and is reheated to become high-quality reheated main steam. Then, it enters the intermediate-pressure cylinder inlet chamber 201 (defined as: steam 007 after the reheating main control valve) through the reheating main steam valve 3 and the reheating main control valve 4. The steam 007 after the reheating main control valve enters the intermediate-pressure cylinder inlet chamber 201 and expands to drive the intermediate-pressure rotor 20 to rotate (defined as: intermediate-pressure inner cylinder steam flow 330). After the intermediate-pressure inner cylinder steam flow 330 expands, it enters the intermediate-pressure cylinder exhaust chamber 204, and finally passes through the intermediate-pressure cylinder extraction chamber 203 or the intermediate-pressure cylinder exhaust chamber 204 for subsequent processes. (The reheat main steam discharged through the intermediate pressure cylinder extraction chamber 203 is defined as: intermediate pressure cylinder first reheat extraction steam 014; the reheat main steam discharged through the intermediate pressure cylinder exhaust chamber 204 is defined as: intermediate pressure cylinder exhaust steam 015).

[0062] In embodiment 1.1, the first bridge steam seal outlet rectifier cavity 208 is connected to the make-up steam cavity 205.

[0063] 1.2 The integral high-pressure inner cylinder 6 does not have a steam injection chamber 205

[0064] like Figure 10 As shown in embodiment 1.2, the steam flow principle in the steam turbine is as follows:

[0065] Step 1: Main steam flows out from the steam generator (usually a boiler), passes through main steam valve 1 and main control valve 2, and enters the high-pressure cylinder inlet steam chamber 200 (defined as: steam after the main control valve 008). That is, the main steam without a make-up steam chamber 205 directly enters the high-pressure cylinder inlet steam chamber 200; there is only one steam path. The remaining steps of Step 1 are the same as Step 1 in 1.1.

[0066] Step 2: The steam entering the first bridge steam seal outlet rectifier chamber 208 enters the extraction chamber 206 of any high-pressure cylinder (defined as: steam 020 passing through the first steam leakage pipe) to recover and utilize the heat energy of high-quality steam.

[0067] Step 3: This step is the same as step 3 in 1.1, and will not be described again here;

[0068] Step 4: This step is the same as step 4 in 1.1, and will not be described again here.

[0069] Furthermore, in embodiment 1.2, the high-pressure cylinder extraction chamber 206 in step 2 has two independent chambers. The steam in the two independent chambers of the high-pressure cylinder extraction chamber 206 is the first regenerative extraction steam 006 and the second regenerative extraction steam 013 of the high-pressure cylinder, respectively. The pressure of the first regenerative extraction steam 006 is greater than the pressure of the second regenerative extraction steam 013 of the high-pressure cylinder.

[0070] In embodiment 1.2, the first bridge steam seal outlet rectifier chamber 208 is connected to an independent chamber in the high-pressure cylinder extraction chamber 206.

[0071] Furthermore, such as Figure 5 As shown, in the embodiment of the two-stage cross-bridge steam seal 80, the steam leakage pipe is defined as the first steam leakage pipe 27, and there are two first steam leakage pipes 27. Because the steam pressure in the rectifier chamber 208 at the outlet of the first cross-bridge steam seal is higher than the steam pressure in the extraction chamber 206 or the make-up chamber 205 of the high-pressure cylinder, the steam in the rectifier chamber 208 at the outlet of the first cross-bridge steam seal will enter the extraction chamber 206 or the make-up chamber 205 of the high-pressure cylinder along the first steam leakage pipe 27 (defined as steam 020 passing through the first steam leakage pipe).

[0072] Furthermore, considering the difference in thermal expansion between the inlet and outlet of the steam leakage connector connected to the integral high-pressure inner cylinder 6, the first steam leakage connector 27 adopts a serpentine pipe structure, and is fixed to the integral high-pressure inner cylinder 6 by butt welding. Taking into account the flow rate and resistance loss of the leaked steam within the first steam leakage connector 27, the first steam leakage connector 27 is positioned in the upper half of the integral high-pressure inner cylinder 6. This eliminates the need to address the drainage issue of the first steam leakage connector 27, thereby simplifying the piping system.

[0073] 2. Second embodiment: The segmented bridge steam seal is a three-section bridge steam seal 800.

[0074] like Figure 6 , Figure 8 , Figure 9 , Figure 11 As shown, the segmented bridge steam seal is configured as a three-segment bridge steam seal 800, including a first bridge steam seal segment 100, a second bridge steam seal segment 101, and a third bridge steam seal segment 102. The bridge steam seal outlet rectifier cavity has two sections, defined as a first bridge steam seal outlet rectifier cavity 208 and a second bridge steam seal outlet rectifier cavity 209. The first bridge steam seal outlet rectifier cavity 208 is located at the outlet of the first bridge steam seal segment 100 and the outlet of the second bridge steam seal segment 101. Between the inlet and outlet of the first bridge steam seal section 101 and the inlet of the third bridge steam seal section 102; the first bridge steam seal outlet rectifier cavity 208 and the second bridge steam seal outlet rectifier cavity 209 are respectively connected to the extraction steam chambers 206 of the two-stage high-pressure cylinders, or the first bridge steam seal outlet rectifier cavity 208 is connected to the make-up steam chamber 205 and the second bridge steam seal outlet rectifier cavity 209 is connected to the extraction steam chamber 206 of any stage high-pressure cylinder.

[0075] Furthermore, the first bridge steam seal section 100 consists of five conventional non-contact labyrinth steam seal rings, the second bridge steam seal section 101 consists of two conventional non-contact labyrinth steam seal rings, and the third bridge steam seal section 102 consists of one conventional non-contact labyrinth steam seal ring. In this embodiment, the three-section bridge steam seal 800 rings adopt a "five + two + one" steam seal ring combination, which can be further customized by considering the pressure at the segmentation points, the steam seal ring structure, and the leakage control target.

[0076] 2.1 The integral high-pressure inner cylinder 6 has a steam injection chamber of 205.

[0077] like Figure 6 As shown in embodiment 2.1, the steam flow principle in the steam turbine is as follows:

[0078] Step 1: This step 1 is the same as step 1 in embodiment 1.1, and will not be described again here;

[0079] Step 2: Part of the leakage steam 302 flowing through the second bridge steam seal section in Step 1 enters the second bridge steam seal outlet rectifier chamber 209, and the other part enters the third bridge steam seal section 102 (defined as: leakage steam 303 flowing through the third bridge steam seal section);

[0080] Step 3: The steam after the main steam valve 1 flows through the make-up steam valve 5 (defined as: steam 009 after the make-up steam valve). The steam 009 after the make-up steam valve enters the make-up steam chamber 205 through the make-up steam valve inlet pipe 26, and is combined with the steam from the first bridge steam seal outlet rectifier chamber 208 to enter the integral high-pressure inner cylinder steam flow 340. After expansion, it enters the high-pressure cylinder exhaust chamber 202. The steam from the second bridge steam seal outlet rectifier chamber 209 merges into the high-pressure cylinder extraction chamber 206 (defined as: steam 021 after the second leakage pipe).

[0081] Step 4: The leaked steam 303 flowing through the third cross-bridge steam seal section in Step 2 is divided into two parts. One part enters the high-pressure cylinder exhaust chamber 202 (defined as: the leaked steam 011 from the cross-bridge steam seal outlet to the high-pressure cylinder exhaust chamber), and the other part enters the medium-pressure steam inlet side balance piston steam seal ring 9 (defined as: the steam 320 leaking through the medium-pressure steam inlet side balance piston steam seal ring).

[0082] Step 5: This step is the same as step 4 in embodiment 1.1, and will not be described again here.

[0083] In embodiment 2.1, the first bridge steam seal outlet rectifier cavity 208 is connected to the make-up steam cavity 205, and the second bridge steam seal outlet rectifier cavity 209 is connected to the high-pressure cylinder extraction steam cavity 206.

[0084] 2.2 The integral high-pressure inner cylinder 6 does not have a steam injection chamber 205

[0085] like Figure 11 As shown in embodiment 2.2, the steam flow principle in the steam turbine is as follows:

[0086] Step 1: This step is the same as step 1 in embodiment 1.2, and will not be described again here;

[0087] Step 2: Part of the leakage steam 302 flowing through the second bridge steam seal section in Step 1 enters the second bridge steam seal outlet rectifier chamber 209, and the other part enters the third bridge steam seal section 102 (defined as: leakage steam 303 flowing through the third bridge steam seal section);

[0088] Step 3: The steam entering the first bridge steam seal outlet rectifier chamber 208 enters the extraction chamber 206 of any high-pressure cylinder (defined as: steam 020 passing through the first steam leakage pipe) for high-quality steam heat energy recovery and utilization; the steam entering the second bridge steam seal outlet rectifier chamber 209 enters the extraction chamber 206 of another high-pressure cylinder (defined as: steam 021 passing through the second steam leakage pipe);

[0089] Step 4: The leaked steam 303 flowing through the third cross-bridge steam seal section in Step 2 is divided into two parts. One part enters the high-pressure cylinder exhaust chamber 202 (defined as: the leaked steam 011 from the cross-bridge steam seal outlet to the high-pressure cylinder exhaust chamber), and the other part enters the medium-pressure steam inlet side balance piston steam seal ring 9 (defined as: the steam 320 leaking through the medium-pressure steam inlet side balance piston steam seal ring).

[0090] Step 5: This step is the same as step 4 in embodiment 1.2, and will not be described again here.

[0091] Furthermore, the high-pressure cylinder extraction chamber 206 in step 3 has two independent chamber stages. The steam in the two independent chambers of the two-stage high-pressure cylinder extraction chamber 206 is the first reheat extraction steam 006 and the second reheat extraction steam 013 of the high-pressure cylinder, respectively. The pressure of the first reheat extraction steam 006 is greater than the pressure of the second reheat extraction steam 013 of the high-pressure cylinder.

[0092] In embodiment 2.2, the first bridge steam seal outlet rectifier cavity 208 and the second bridge steam seal outlet rectifier cavity 209 are respectively connected to the first reheat extraction steam 006 and the second reheat extraction steam 013 of the high-pressure cylinder formed by the two independent chambers.

[0093] Furthermore, combining embodiments 2.1 and 2.2, as follows... Figure 9 As shown, in the embodiment of the three-section cross-bridge steam seal 800, the steam leakage pipes are defined as a first steam leakage pipe 27 and a second steam leakage pipe 28. There are two first steam leakage pipes 27 (set on the first cross-bridge steam seal outlet rectifier chamber 208), and there are two second steam leakage pipes 28 (set on the second cross-bridge steam seal outlet rectifier chamber 209). Because the steam pressure in the first cross-bridge steam seal outlet rectifier chamber 208 and the steam pressure in the second cross-bridge steam seal outlet rectifier chamber 209 are higher than the steam pressure in the high-pressure cylinder extraction chamber 206 or the make-up steam chamber 205, the steam in the first cross-bridge steam seal outlet rectifier chamber 208 will enter the high-level high-pressure cylinder extraction chamber 206 or the make-up steam chamber 205 along the first steam leakage pipe 27, and the steam in the second cross-bridge steam seal outlet rectifier chamber 209 will enter the low-level high-pressure cylinder extraction chamber 206 along the second steam leakage pipe 28.

[0094] Furthermore, considering the thermal expansion differences between the inlet and outlet of each steam leakage connector in the integral high-pressure inner cylinder 6, both the first steam leakage connector 27 and the second steam leakage connector 28 adopt a similar serpentine pipe structure, and each steam leakage connector is fixed to the integral high-pressure inner cylinder 6 by butt welding. Similar to the first steam leakage connector, considering the flow rate and resistance loss of leaked steam in the second steam leakage connector 28, the second steam leakage connector 28 is also arranged in the upper half of the integral high-pressure inner cylinder 6. This eliminates the need to address the drainage problem of the second steam leakage connector 28, thereby simplifying the piping system.

[0095] Furthermore, in the above embodiment, the balance pipe is used to connect the cavity between the high-pressure exhaust side balance piston steam seal ring 10 and the intermediate-pressure outer cylinder 21 with the intermediate-pressure cylinder exhaust cavity 204 (defined as: balance pipe steam 010), to balance the axial thrust of the intermediate-pressure rotor 20. Frequency regulation or full-load output requirements under high back pressure conditions are achieved by opening or adjusting the valve opening of the make-up steam valve 5. When the make-up steam valve 5 is closed, only steam 020 passing through the first leakage pipe flows into the make-up steam cavity 205.

[0096] To achieve the above or other objectives, the present invention also discloses a method for reducing steam leakage in a segmented bridge steam seal, the steps of which are as follows:

[0097] A1: Based on the thermodynamic parameters such as the steam inlet pressure P1 of the integral high-pressure inner cylinder, the steam inlet pressure P2 of the intermediate-pressure inner cylinder, the steam replenishment chamber pressure P3, the steam extraction pressure P4 of the integral high-pressure inner cylinder, the steam exhaust pressure P5 of the integral high-pressure inner cylinder, and the steam exhaust pressure P6 of the intermediate-pressure inner cylinder, determine the arrangement and combination of the segmented bridge steam seals; in particular, based on the specific pressure data and pressure ratio of the integral high-pressure inner cylinder inlet pressure P1, the integral high-pressure inner cylinder exhaust pressure P5, and the intermediate-pressure inner cylinder exhaust pressure P6, and considering the overall axial space of the segmented bridge steam seals, determine the combination form of the segmented bridge steam seals;

[0098] A2: Based on the integral high-pressure inner cylinder inlet steam pressure P1, the intermediate-pressure inner cylinder inlet steam pressure P2, the structural parameters of the steam seal teeth in each steam seal section, and the axial and radial hot-state operating clearance data of each steam seal section, calculate the pressure P at the inlet and outlet of each steam seal ring assembly section. ij The total steam leakage M of each steam seal section i And the critical pressure ratio P of each steam seal section under the corresponding steam seal structure and thermodynamic parameter boundary conditions. ki (i and j represent the i-th steam seal section, respectively. A value of 0 for j represents the inlet of a steam seal section, and a value of 1 for j represents the outlet of a steam seal section. The outlet pressure of the steam seal section should be selected to avoid reaching the critical state.)

[0099] A3: Based on the leakage rate M of each section of the segmented bridge steam seal. i Export pressure P ij and the pressure Q at the point of entry into the flow pathi Calculate the steam pressure loss ΔP within several leaking pipes to determine the pipe diameter, flow velocity, pipe routing, and related structural design; pipe pressure loss ΔP, outlet pressure P ij and the pressure Q at the point of entry into the flow path i The three should satisfy Q. i +ΔP=P ij relation;

[0100] A4: Calculate the steam leakage data when using a segmented bridge steam seal; calculate the steam leakage data when using an integral bridge steam seal, and compare the two.

[0101] The pressure Q at the confluence point in step A3 i This includes not only the pressure at the connection between the high-pressure cylinder extraction chamber 206 and the leakage pipe, but also the pressure at the connection between the make-up steam chamber 205 and the leakage pipe.

[0102] The steam leakage in step A4 refers to the amount of main steam in the integral high-pressure inner cylinder 6 that enters the high-pressure cylinder exhaust chamber 202 through the cross-bridge steam seal (including the integral cross-bridge steam seal 8 and the segmented cross-bridge steam seal).

[0103] The leakage rates of the two-section cross-bridge steam seal 80 in the first embodiment and the three-section cross-bridge steam seal 800 in the third embodiment are now compared with those of the integral cross-bridge steam seal 8; the details are as follows:

[0104] ① First, the comparison is based on the following premises: non-contact labyrinthine steam seal rings with the same structure, and identical axial and radial hot operating clearances between the steam seal teeth; the integral high-pressure inner cylinder inlet steam pressure P1 is 23.6 MPa(a), the make-up steam chamber pressure P3 is 10.427 MPa(a), and the integral high-pressure inner cylinder exhaust steam pressure P5 is 4.436 MPa(a). Within the specific axial arrangement space of the bridge steam seal, the integral bridge steam seal 8 can arrange nine steam seal rings; the two-stage bridge steam seal 80, due to the setting of the first bridge steam seal outlet rectifier chamber 208, can arrange a maximum of "five + three", totaling eight steam seal rings; the three-stage bridge steam seal 800 can arrange a maximum of "five + two + one", totaling eight steam seal rings.

[0105] ② When the integral bridge steam seal 8 is used, the theoretical calculated value of the steam 300 leaking through the integral bridge steam seal is 8.46 kg / s (that is, 30.47 t / h);

[0106] ③ When a two-stage bridge steam seal 80 is used, the theoretically calculated value of the leakage steam 301 flowing through the first bridge steam seal section is 10.37 kg / s, and the theoretically calculated value of the leakage steam 302 flowing through the second bridge steam seal section is 5.95 kg / s (i.e., 21.43 t / h). The theoretically calculated value of the steam 020 entering the make-up steam chamber 205 from the rectifier chamber 208 at the outlet of the first bridge steam seal through the first leakage pipe is 4.42 kg / s (i.e., 10.37 - 5.9). 5 = 4.42), that is, the amount of steam from the integral high-pressure inner cylinder 6 through the two-stage cross-bridge steam seal 80 is 5.95 kg / s, which is 30% lower than the amount of steam from the integral cross-bridge steam seal 8 (1 - 5.95 / 8.46 * 100%). Approximately 42.6% (4.42 / 10.37 * 100%) of the steam re-enters the steam replenishment chamber 205 through the first steam leakage pipe 27 and merges into the integral high-pressure inner cylinder steam flow 340 to continue to expand and do work;

[0107] ④ When using the three-section cross-bridge steam seal 800, the extraction pressure P4 of the integral high-pressure inner cylinder is set to 6.75 MPa(a). The theoretical calculated value of the leakage steam 301 flowing through the first cross-bridge steam seal section is 10.37 kg / s, the theoretical calculated value of the leakage steam 302 flowing through the second cross-bridge steam seal section is 6.14 kg, the amount of steam 020 entering the make-up steam chamber 205 through the first leakage pipe is 4.23 kg / s (10.37-6.14=4.23), the theoretical calculated value of the leakage steam 303 flowing through the third cross-bridge steam seal section is 5.55 kg / s (i.e. 20 t / h), and the theoretical calculated value of the steam 021 flowing through the second leakage pipe is 0.59 kg / s (6.14-5.55=0.59). Compared with the integral cross-bridge steam seal 8, the steam quantity is reduced by 34% (1-5.55 / 8.46*100%).

[0108] In summary, by adopting a segmented cross-bridge steam seal, and by setting several cross-bridge steam seal outlet rectifier chambers within the segmented cross-bridge steam seal, the leaking steam in the cross-bridge steam seal is further depressurized and throttled in stages, and introduced into the make-up steam chamber 205 or the high-pressure cylinder extraction steam chamber 206 through several cross-bridge steam seal outlet rectifier chambers. While ensuring the extraction steam parameter requirements, more main steam in the integral high-pressure inner cylinder 6 expands and does work, further improving the flow efficiency of the integral high-pressure inner cylinder 6.

[0109] To achieve the above or other objectives, the present invention also relates to a steam turbine including the aforementioned segmented bridge steam seal for reducing steam leakage.

[0110] The segmented cross-bridge steam seal, method, and steam turbine for reducing steam leakage involved in this invention have the following beneficial effects:

[0111] 1. This application is based on the non-contact labyrinth steam seal ring, which has a large number of engineering application performance, simple structure and controllable processing and manufacturing costs, and relatively stable operating performance. By dividing the integral bridge steam seal into multiple steam seal sections and multiple bridge steam seal outlet rectifier cavities, the total steam leakage of the bridge steam seal is reduced to the greatest extent by adopting step-by-step pressure reduction and throttling.

[0112] 2. By introducing appropriate flow stage pressure parameters, under suitable pressure ratios, high-quality leaked steam from each steam seal section can be recovered and returned to the flow path to continue expanding and doing work, realizing the cascade utilization of energy and further ensuring the cylinder efficiency level of each cylinder of the steam turbine.

[0113] 3. This application makes full use of the structure of the high-pressure combined cylinder steam turbine, especially the structure of the integral high-pressure inner cylinder, the arrangement characteristics of the high-pressure cylinder extraction chamber 206 and the make-up steam chamber 205, and proposes a control method to reduce the total steam leakage in the bridge steam seal area from the perspective of the entire cylinder module, and reuses the high-quality steam leakage.

[0114] 4. This application enables the reuse of leaked main steam in segmented bridge steam seals, solving the problems of large steam leakage, waste of heat energy in high-quality steam, and high overall heat consumption rate in the prior art.

[0115] 5. After the turbine unit in this application has been in service for a long time, the steam leakage of each steam seal section in the segmented bridge steam seal increases. However, since the steam is recovered and enters the flow path to continue to expand and do work, its impact on the flow efficiency of the entire integral high-pressure inner cylinder 6 is negligible. This arrangement is superior to the conventional integral bridge steam seal 8.

[0116] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0117] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for reducing steam leakage in a segmented bridge steam seal, characterized in that: A segmented cross-bridge steam seal for reducing steam leakage is adopted and applied in a steam turbine. The steam turbine includes an intermediate and high-pressure outer cylinder (21), an integral high-pressure inner cylinder (6), an intermediate-pressure inner cylinder (7), a segmented cross-bridge steam seal, and an intermediate and high-pressure rotor (20). The integral high-pressure inner cylinder (6) and the intermediate-pressure inner cylinder (7) are both located in the intermediate and high-pressure outer cylinder (21), and the segmented cross-bridge steam seal is located between the integral high-pressure inner cylinder (6) and the intermediate-pressure inner cylinder (7). The segmented cross-bridge steam seal is provided with several cross-bridge steam seal outlet rectifier chambers. The integral high-pressure inner cylinder (6) includes several high-pressure cylinder extraction chambers (206) and several steam leakage pipes. Several bridge steam seal outlet rectifier chambers are connected to several high-pressure cylinder extraction chambers (206) through steam leakage pipes. The main steam enters the integral high-pressure inner cylinder (6) and is divided into two paths. One path of main steam expands and does work in the integral high-pressure inner cylinder (6) to drive the high-pressure and medium-pressure rotor (20) to rotate. The other path of main steam enters the segmented bridge steam seal and enters several high-pressure cylinder extraction chambers (206) through several bridge steam seal outlet rectifier chambers for recycling. The steps of the segmented bridge steam seal method for reducing steam leakage are as follows: S1: Determine the pressure data and pressure ratio of the three components: the steam inlet pressure of the integral high-pressure inner cylinder (6), the steam outlet pressure of the integral high-pressure inner cylinder (6), and the steam inlet pressure of the intermediate-pressure inner cylinder (7). Combined with the axial arrangement space of the segmented bridge steam seal, determine the number of segments of the segmented bridge steam seal. S2: Based on the steam inlet pressure of the integral high-pressure inner cylinder (6), the steam outlet pressure of the integral high-pressure inner cylinder (6), the structural parameters of the steam seal teeth in each steam seal section, and the axial and radial hot operating clearance data of each steam seal section, calculate and evaluate the pressure of the rectifier cavity at the outlet of each bridge steam seal and the corresponding steam leakage of each steam seal section. S3: Based on the leakage of each steam seal section, the number of steam leakage pipes, the selected pipe diameter and pipeline layout of the steam leakage pipes, calculate and evaluate the pipeline pressure loss between the rectifier chamber at the outlet of each bridge steam seal and the high-pressure cylinder extraction chamber (206), and meet the following requirements: the pressure of the rectifier chamber at the outlet of each bridge steam seal minus the pipeline pressure loss of the steam leakage pipe is equal to the pressure of the high-pressure cylinder extraction chamber (206) at the connection of the steam leakage pipe.

2. The method for reducing steam leakage using a segmented bridge steam seal according to claim 1, characterized in that: In step S3, if the pressure of the rectifier chamber at the outlet of each bridge steam seal, the pressure loss of the steam leakage pipe, and the pressure of the high-pressure cylinder extraction chamber (206) at the connection of the steam leakage pipe cannot meet the above requirements, the diameter, quantity, and pipeline layout of the steam leakage pipe should be adjusted to regulate the pressure loss of the steam leakage pipe; or the number of steam seal teeth in each steam seal section in step S2 should be adjusted to regulate the pressure of the rectifier chamber at the outlet of each bridge steam seal.

3. The method for reducing steam leakage using a segmented bridge steam seal according to claim 1, characterized in that: The integral high-pressure inner cylinder (6) also includes a steam replenishment chamber (205), and the high-medium pressure outer cylinder (21) is also provided with a steam replenishment valve inlet pipe (26), and a steam replenishment valve (5) is provided on the steam replenishment valve inlet pipe (26). The steam replenishment valve inlet pipe (26) is connected to the steam replenishment chamber (205); any of the bridge steam seal outlet rectifier chambers is connected to the steam replenishment chamber (205) through a steam leakage pipe.

4. The method for reducing steam leakage using a segmented bridge steam seal according to claim 1 or 3, characterized in that: The segmented cross-bridge steam seal includes a two-section cross-bridge steam seal (80). The number of the cross-bridge steam seal outlet rectifier cavity is one. The cross-bridge steam seal outlet rectifier cavity is connected to any high-pressure cylinder extraction steam cavity (206); or the cross-bridge steam seal outlet rectifier cavity is connected to the make-up steam cavity (205).

5. The method for reducing steam leakage using a segmented bridge steam seal according to claim 4, characterized in that: The number of the steam leakage pipes is at least one, and the steam leakage pipes connect the rectifier cavity of the bridge steam seal outlet to any high-pressure cylinder extraction cavity (206) or the steam leakage cavity of the bridge steam seal outlet to the make-up steam cavity (205).

6. The method for reducing steam leakage in a segmented bridge steam seal according to claim 1 or 3, characterized in that: The segmented bridge steam seal includes a three-section bridge steam seal (800), and the number of the bridge steam seal outlet rectifier cavities is two. The two bridge steam seal outlet rectifier cavities are connected to any two high-pressure cylinder extraction steam cavities (206); or the two bridge steam seal outlet rectifier cavities are respectively connected to the make-up steam cavity (205) and any one of the high-pressure cylinder extraction steam cavities (206).

7. The method for reducing steam leakage using a segmented bridge steam seal according to claim 6, characterized in that: The number of the steam leakage pipes is at least two. The two bridge steam seal outlet rectifier cavities are connected to any two high-pressure cylinder extraction steam cavities (206) through the steam leakage pipes, or the two bridge steam seal outlet rectifier cavities are connected to the make-up steam cavity (205) and any one high-pressure cylinder extraction steam cavity (206) respectively.

8. A steam turbine, characterized in that: The segmented bridge steam seal used in the method for reducing steam leakage as described in any one of claims 1-7.

9. The steam turbine according to claim 8, characterized in that: It also includes a high-pressure cylinder inlet chamber (200), a high-pressure cylinder exhaust chamber (202), a medium-pressure cylinder inlet chamber (201), and a medium-pressure cylinder exhaust chamber (204). A high-pressure exhaust side balance piston steam seal ring (10) is also provided between the high-pressure cylinder exhaust chamber (202) and the high-medium-pressure outer cylinder (21). A medium-pressure inlet side balance piston steam seal ring (9) is also provided between the high-pressure cylinder exhaust chamber (202) and the medium-pressure inner cylinder (7). A high-pressure exhaust side balance piston steam seal ring outlet rectifier chamber (207) is formed between the high-pressure exhaust side balance piston steam seal ring (10) and the high-medium-pressure outer cylinder (21). The high-pressure exhaust side balance piston steam seal ring outlet rectifier chamber (207) and the medium-pressure cylinder exhaust chamber (204) are connected by a balance pipe.

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