A passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders

Abstract

The application discloses a kind of for supercritical CO2 turbine cylinder shaft seal passive adaptive sealing system, including high-pressure outer cylinder and coaxially arranged in high-pressure outer cylinder high-pressure inner cylinder;Upper gas seal chamber and lower gas seal chamber are respectively arranged on the inner side of high-pressure inner cylinder upper half and high-pressure inner cylinder lower half at the end seal of high-pressure inner cylinder;Upper through-flow chamber and lower through-flow chamber are respectively arranged on the inner side of high-pressure inner cylinder upper half and high-pressure inner cylinder lower half at the flow section of high-pressure inner cylinder;First self-flow gas guide pipe is communicated between upper through-flow chamber and upper gas seal chamber, and first drainage channel is formed by the directional flow of upper through-flow chamber to upper gas seal chamber;Second self-flow gas guide pipe is communicated between lower gas seal chamber and lower through-flow chamber, and second drainage channel is formed by the directional flow of lower gas seal chamber to lower through-flow chamber.The application can significantly improve the sealing efficiency of the system, effectively reduce the heat loss, reduce unnecessary air leakage, and realize the economic efficiency and reliability of equipment operation.

Description

Technical Field

[0001] This invention belongs to the field of turbine cylinder technology, specifically a passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders. Background Technology

[0002] Supercritical CO2 power cycles have broad prospects in fields such as fourth-generation nuclear energy, solar thermal power generation, and ship propulsion due to their advantages such as high energy conversion efficiency and compact system structure. Among them, the turbine is the core working component, and the shaft end seal between its rotor and the stationary cylinder is the key to ensuring cycle efficiency and safe operation.

[0003] Supercritical CO2 exhibits drastic changes in physical properties (such as density and viscosity) near its critical point. Current technologies typically employ labyrinth seals, dry gas seals, or a combination of both. However, these methods present the following problems: 1) The labyrinth seal has inherent leakage, which negatively impacts circulation efficiency; 2) Active seals such as dry gas seals require complex external gas sources, filtration systems and control systems, which increases system complexity and potential failure points, and may lag in response under transient conditions.

[0004] With the development of high-power, high-parameter supercritical CO2 turbine units, higher requirements have been placed on the reliability and adaptability of cylinder shaft end seals. High-power, high-parameter supercritical CO2 high-pressure modules adopt an inner and outer double-layer cylinder structure; the high-pressure inner cylinder often uses a single-flow cylinder structure, resulting in leakage at the end of the high-pressure inner cylinder into the cylinder interlayer between the high-pressure inner and outer cylinders. Because the high-parameter supercritical CO2 working fluid entering the high-pressure inner cylinder directly enters the cylinder interlayer through the shaft seal at the end of the high-pressure inner cylinder, the working mass entering the cylinder interlayer is relatively large, and the temperature is also relatively high. Significant high-temperature leakage increases the unit's heat consumption and also leads to an increase in the temperature of the outer cylinder, affecting the lifespan of the outer cylinder and the flange sealing performance.

[0005] To address the aforementioned issues, there is an urgent need to develop a novel shaft sealing technology that is simple in structure, requires no external intervention, and can adapt to changes in supercritical CO2 operating conditions. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders that can reduce air leakage and lower the leakage temperature of the shaft seal entering the outer cylinder.

[0007] The technical objective of this invention is achieved through the following technical solution: A passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders includes a high-pressure outer cylinder and a high-pressure inner cylinder coaxially disposed within the high-pressure outer cylinder; an upper sealing chamber and a lower sealing chamber are respectively provided at the end shaft seal of the high-pressure inner cylinder, on the inner side of the upper half and the lower half of the high-pressure inner cylinder; The high-pressure inner cylinder has an upper flow passage chamber and a lower flow passage chamber respectively located on the inner side of the upper and lower halves of the high-pressure inner cylinder. The upper flow passage chamber is connected to the upper air seal chamber by a first gravity-flow air pipe, forming a first flow channel that directs flow from the upper flow passage chamber to the upper air seal chamber. The first gravity-flow air pipe is located between the upper half of the high-pressure outer cylinder and the upper half of the high-pressure inner cylinder. The lower air seal chamber is connected to the lower flow passage chamber by a second gravity-flow air pipe, forming a second flow channel that directs flow from the lower air seal chamber to the lower flow passage chamber. The second gravity-flow air pipe is located between the lower half of the high-pressure outer cylinder and the lower half of the high-pressure inner cylinder.

[0008] Preferably, the upper and lower air-sealing chambers are two annular grooves spaced axially on the inner side of the end shaft seal of the high-pressure inner cylinder; the upper and lower flow passage chambers are two annular grooves spaced axially on the inner side of the flow passage section of the high-pressure inner cylinder; the upper half of the high-pressure inner cylinder is radially provided with a first air-sealing chamber interface connecting the outer wall of the upper half of the high-pressure inner cylinder and the upper air-sealing chamber, and a first flow passage chamber interface connecting the outer wall of the upper half of the high-pressure inner cylinder and the upper flow passage chamber; the lower half of the high-pressure inner cylinder is radially provided with a second air-sealing chamber interface connecting the outer wall of the lower half of the high-pressure inner cylinder and the lower air-sealing chamber, and a second flow passage chamber interface connecting the outer wall of the lower half of the high-pressure inner cylinder and the lower flow passage chamber; one end of the first gravity-flow air pipe is detachably connected to the first air-sealing chamber interface, and the other end is detachably connected to the first flow passage chamber interface; one end of the second gravity-flow air pipe is detachably connected to the second air-sealing chamber interface, and the other end is detachably connected to the second flow passage chamber interface.

[0009] Preferably, both ends of the first gravity-flow air pipe are provided with screw-in pipe fittings, and the first air-sealed chamber interface and the first flow-through chamber interface are respectively provided with internal threads that are threadedly connected to the screw-in pipe fittings; both ends of the second gravity-flow air pipe are provided with screw-in pipe fittings, and the second air-sealed chamber interface and the second flow-through chamber interface are respectively provided with internal threads that are threadedly connected to the screw-in pipe fittings.

[0010] Preferably, the two ends of the first and second self-flowing air pipes are welded to screw-in pipe fittings.

[0011] Preferably, the screw-in pipe joint, the first self-flowing air tube, and the second self-flowing air tube are all made of high-temperature resistant alloy material, and their inner walls are surface hardened.

[0012] Preferably, multiple red rings are provided at the end shaft seal of the high-pressure inner cylinder at axial intervals on the outside of the high-pressure inner cylinder; the upper air seal chamber and the lower air seal chamber are arranged at axial intervals on the inner side of the high-pressure inner cylinder near the red rings.

[0013] Preferably, a cylinder interlayer is provided between the high-pressure inner cylinder and the high-pressure outer cylinder, at the end shaft seal of the high-pressure outer cylinder, the upper air seal chamber is disposed close to the cylinder interlayer, and the lower air seal chamber is disposed at intervals on the side of the upper air seal chamber away from the cylinder interlayer.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention helps to significantly improve the sealing efficiency of the system, thereby effectively reducing heat loss, minimizing unnecessary air leakage, and ultimately improving the economy and reliability of equipment operation.

[0015] 2. This invention simplifies the manufacturing process of the high-pressure inner cylinder and reduces manufacturing costs by setting the upper air-sealing chamber, lower air-sealing chamber, upper flow chamber, and lower flow chamber as annular grooves on the high-pressure inner cylinder and arranging a detachable self-flowing air pipe. At the same time, it facilitates the installation, maintenance, and replacement of the self-flowing air pipe, thereby improving the maintainability of the system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 A schematic diagram showing the connection of the second self-flowing air pipe, the screw-in pipe joint, and the lower half of the high-pressure inner cylinder. Reference numerals: 11—Upper half of high-pressure outer cylinder; 12—Lower half of high-pressure outer cylinder; 21—Upper half of high-pressure inner cylinder; 22—Lower half of high-pressure inner cylinder; 31—Upper air-sealing chamber; 32—Lower air-sealing chamber; 41—Upper flow chamber; 42—Lower flow chamber; 51—First self-flowing air pipe; 52—Second self-flowing air pipe; 61—First air-sealing chamber interface; 62—Second air-sealing chamber interface; 71—First flow chamber interface; 72—Second flow chamber interface; 8—Screw-in pipe fitting; 9—Red collar; 101—Cylinder jacket. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0020] like Figure 1 , Figure 2 As shown, a passive adaptive sealing system for a supercritical CO2 turbine cylinder shaft seal includes a high-pressure outer cylinder and a high-pressure inner cylinder coaxially disposed within the high-pressure outer cylinder; an upper sealing chamber 31 and a lower sealing chamber 32 are respectively provided at the end shaft seal of the high-pressure inner cylinder, on the inner sides of the upper half 21 and the lower half 22 of the high-pressure inner cylinder; an upper flow passage chamber 41 and a lower flow passage chamber 42 are respectively provided at the flow passage section of the high-pressure inner cylinder, on the inner sides of the upper half 21 and the lower half 22 of the high-pressure inner cylinder; the upper flow passage chamber 41 and the upper sealing chamber 32 are respectively connected. The upper part 11 of the high-pressure outer cylinder and the upper part 21 of the high-pressure inner cylinder are connected by a first gravity-flow duct 51, forming a first drainage channel that directs flow from the upper flow chamber 41 to the upper air seal chamber 31. The first gravity-flow duct 51 is located between the upper part 11 of the high-pressure outer cylinder and the upper part 21 of the high-pressure inner cylinder. The lower air seal chamber 32 and the lower flow chamber 42 are connected by a second gravity-flow duct 52, forming a second drainage channel that directs flow from the lower air seal chamber 32 to the lower flow chamber 42. The second gravity-flow duct 52 is located between the lower part 12 of the high-pressure outer cylinder and the lower part 22 of the high-pressure inner cylinder. Through the first drainage channel that connects the upper flow chamber 41 and the upper air seal chamber 31, and the second drainage channel that connects the lower air seal chamber 32 and the lower flow chamber 42, the leakage working fluid is driven to recover by gravity flow using a pressure gradient. This achieves passive adaptive sealing of the supercritical CO2 turbine cylinder shaft seal, significantly reducing leakage and lowering leakage temperature, thereby improving the unit's economy and the life of the outer cylinder.

[0021] like Figure 1 As shown, in this embodiment, the high-pressure outer cylinder includes an upper high-pressure outer cylinder 11 and a lower high-pressure outer cylinder 12. The high-pressure inner cylinder includes an upper high-pressure inner cylinder 21 and a lower high-pressure inner cylinder 22.

[0022] In practice, the first gravity-flow air pipe 51 is installed between the upper half 11 of the high-pressure outer cylinder and the upper half 21 of the high-pressure inner cylinder. The second gravity-flow air pipe 52 is installed between the lower half 12 of the high-pressure outer cylinder and the lower half 22 of the high-pressure inner cylinder.

[0023] like Figure 1 As shown, the upper air-sealing chamber 31 and the lower air-sealing chamber 32 are two annular grooves spaced axially on the inner side of the end shaft seal of the high-pressure inner cylinder; the upper flow passage chamber 41 and the lower flow passage chamber 42 are two annular grooves spaced axially on the inner side of the flow passage section of the high-pressure inner cylinder; the upper half 21 of the high-pressure inner cylinder is provided radially with a first air-sealing chamber interface 61 connecting the outer wall of the upper half 21 of the high-pressure inner cylinder and the upper air-sealing chamber 31, and a first flow passage chamber interface 71 connecting the outer wall of the upper half 21 of the high-pressure inner cylinder and the upper flow passage chamber 41; the lower half 2... 2. A second air-sealing chamber interface 62, connecting the outer wall of the lower half 22 of the high-pressure inner cylinder and the lower air-sealing chamber 32, and a second flow-through chamber interface 72, connecting the outer wall of the lower half 22 of the high-pressure inner cylinder and the lower flow-through chamber 42, are provided radially. One end of the first self-flowing air pipe 51 is detachably connected to the first air-sealing chamber interface 61, and the other end is detachably connected to the first flow-through chamber interface 71. One end of the second self-flowing air pipe 52 is detachably connected to the second air-sealing chamber interface 62, and the other end is detachably connected to the second flow-through chamber interface 72. By setting the upper air-sealing chamber 31, lower air-sealing chamber 32, upper flow-through chamber 41, and lower flow-through chamber 42 as annular grooves on the high-pressure inner cylinder and arranging detachably connected self-flowing air pipes, the processing technology of the high-pressure inner cylinder is greatly simplified, the manufacturing cost is reduced, and the installation, maintenance, and replacement of the self-flowing air pipes are facilitated, thus improving the maintainability of the system.

[0024] like Figure 1 As shown, in this embodiment, two red rings 9 are provided at the end shaft seal of the high-pressure inner cylinder and at axial intervals on the outside of the high-pressure inner cylinder; the upper air seal chamber 31 and the lower air seal chamber 32 are provided at axial intervals on the inner side of the high-pressure inner cylinder near the red rings 9.

[0025] The high-pressure inner cylinder and the high-pressure outer cylinder are connected by a cylinder interlayer 101 at the end shaft seal of the high-pressure outer cylinder. The upper air seal chamber 31 is located close to the cylinder interlayer 101, and the lower air seal chamber 32 is spaced apart on the side of the upper air seal chamber 31 away from the cylinder interlayer 101.

[0026] The upper flow chamber 41 and the lower flow chamber 42 are two annular grooves spaced axially on the inner side of the flow section of the high-pressure inner cylinder; the upper flow chamber 41 is located on the side of the lower flow chamber 42 near the cylinder interlayer 101.

[0027] like Figure 1 As shown, screw-in pipe fittings 8 are respectively provided at both ends of the first self-flowing air intake pipe 51, and the first air-sealed chamber interface 61 and the first flow-through chamber interface 71 are respectively provided with internal threads that are threadedly connected to the screw-in pipe fittings 8; screw-in pipe fittings 8 are respectively provided at both ends of the second self-flowing air intake pipe 52, and the second air-sealed chamber interface 62 and the second flow-through chamber interface 72 are respectively provided with internal threads that are threadedly connected to the screw-in pipe fittings 8.

[0028] Specifically, the two ends of the first self-flowing air pipe 51 and the second self-flowing air pipe 52 are welded to the screw-in pipe fitting 8, respectively. For example... Figure 2 As shown, one end of the screw-in pipe fitting 8 is welded to one end of the second self-flowing air pipe 52.

[0029] In practice, the screw-in pipe joint 8, the first self-flowing air pipe 51 and the second self-flowing air pipe 52 are all made of high-temperature resistant alloy materials, and their inner walls are surface hardened.

[0030] Working principle: Under normal operating conditions of the turbine, the pressure at the inlet of the high-pressure inner cylinder remains the highest, successively exceeding the pressure in the upper flow chamber 41 and the lower flow chamber 42, forming a stable pressure gradient distribution. There is air leakage at the gas seal at the end of the high-pressure inner cylinder's intake chamber. This leakage first enters the lower gas seal chamber 32 and then continues to flow to the lower flow chamber 42, where the pressure is lower.

[0031] Meanwhile, the upper flow chamber 41 and the upper air seal chamber 31 are interconnected through the first gravity flow air inlet pipe 51. Since the pressure of the upper flow chamber 41 is higher than that of the lower flow chamber 42 and the lower air seal chamber 32, and the upper air seal chamber 31 and the lower air seal chamber 32 are adjacent and connected, the leakage in the upper air seal chamber 31 is divided into two paths under the action of pressure difference: one path flows in reverse into the lower air seal chamber 32 with lower pressure, and finally merges into the lower flow chamber 42 through the second flow channel; the other path flows outward into the cylinder interlayer 101 space between the high-pressure inner cylinder and the high-pressure outer cylinder.

[0032] In practical use, after the working fluid in the upper flow chamber 41 completes its expansion and work, its temperature and pressure have significantly decreased. Therefore, when it leaks into the cylinder jacket 101, its temperature is significantly lower than that of the high-temperature working fluid that leaks directly into the jacket from the main flow channel, which helps to reduce the local heat load on the cylinder. This technical measure helps to significantly improve the sealing efficiency of the system, thereby effectively reducing heat loss, minimizing unnecessary leakage, and ultimately improving the economy and reliability of equipment operation.

[0033] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders, characterized in that, This includes a high-pressure outer cylinder and a high-pressure inner cylinder coaxially mounted within the high-pressure outer cylinder; The high-pressure inner cylinder has an upper air seal chamber and a lower air seal chamber respectively located at the end shaft seal, on the inner side of the upper half and the lower half of the high-pressure inner cylinder. The high-pressure inner cylinder has an upper flow passage chamber and a lower flow passage chamber respectively located on the inner side of the upper half and lower half of the high-pressure inner cylinder. The upper flow chamber and the upper air seal chamber are connected by a first gravity flow air pipe, forming a first flow channel that directs flow from the upper flow chamber to the upper air seal chamber, and the first gravity flow air pipe is located between the upper half of the high-pressure outer cylinder and the upper half of the high-pressure inner cylinder. The lower air seal chamber and the lower flow chamber are connected by a second gravity-flow air pipe, forming a second flow channel that directs flow from the lower air seal chamber to the lower flow chamber. The second gravity-flow air pipe is located between the lower half of the high-pressure outer cylinder and the lower half of the high-pressure inner cylinder.

2. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 1, characterized in that, The upper and lower air seal chambers are two annular grooves spaced axially on the inner side of the end shaft seal of the high-pressure inner cylinder. The upper flow chamber and the lower flow chamber are two annular grooves spaced axially on the inner side of the flow section of the high-pressure inner cylinder. The upper half of the high-pressure inner cylinder is provided radially with a first air seal chamber interface connecting the outer wall of the upper half of the high-pressure inner cylinder and the upper air seal chamber, and a first flow passage chamber interface connecting the outer wall of the upper half of the high-pressure inner cylinder and the upper flow passage chamber. The lower half of the high-pressure inner cylinder is provided radially with a second air seal chamber interface connecting the outer wall of the lower half of the high-pressure inner cylinder and the lower air seal chamber, and a second flow passage chamber interface connecting the outer wall of the lower half of the high-pressure inner cylinder and the lower flow passage chamber. One end of the first self-flowing air tube is detachably connected to the interface of the first air-sealed chamber, and the other end is detachably connected to the interface of the first flow chamber. One end of the second self-flowing air tube is detachably connected to the interface of the second air-sealed chamber, and the other end is detachably connected to the interface of the second flow chamber.

3. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 2, characterized in that, Both ends of the first self-flowing air pipe are respectively provided with screw-in pipe joints, and the first air-sealed chamber interface and the first flow-through chamber interface are respectively provided with internal threads that are threadedly connected to the screw-in pipe joints. The two ends of the second self-flowing air pipe are respectively provided with screw-in pipe joints, and the second air-sealed chamber interface and the second flow chamber interface are respectively provided with internal threads that are threadedly connected to the screw-in pipe joints.

4. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 3, characterized in that, The two ends of the first and second self-flowing air pipes are respectively welded to screw-in pipe fittings.

5. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 3, characterized in that, The screw-in pipe joint, the first self-flowing air tube, and the second self-flowing air tube are all made of high-temperature resistant alloy material, and their inner walls are surface hardened.

6. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 1 or 2, characterized in that, The high-pressure inner cylinder has multiple red rings spaced axially at the end shaft seal and on the outside of the high-pressure inner cylinder; the upper and lower air seal chambers are spaced axially on the inside of the high-pressure inner cylinder near the red rings.

7. The passive adaptive sealing system for shaft seals of supercritical CO2 turbine cylinders according to claim 6, characterized in that, A cylinder interlayer is provided between the high-pressure inner cylinder and the high-pressure outer cylinder, at the end shaft seal of the high-pressure outer cylinder. The upper air seal chamber is located close to the cylinder interlayer, and the lower air seal chamber is spaced apart on the side of the upper air seal chamber away from the cylinder interlayer.

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