A supercritical carbon dioxide turbine generator self-circulation dry seal device

Abstract

The application discloses a supercritical carbon dioxide turbine generator self-circulation dry seal device, which is used for dynamic seal of a high specific power and compact supercritical carbon dioxide power system turbine generator set and comprises a labyrinth seal ring, a seal cavity and a dry seal body. The labyrinth seal is used as a first-stage seal structure of the self-circulation dry seal device and can significantly reduce the carbon dioxide pressure discharged into the seal cavity. The dry seal body is used for inhibiting the leakage of the carbon dioxide in the seal cavity to a low-pressure side. The seal cavity is connected with a low-pressure node of a parent machine and forms a self-circulation loop. Through the self-circulation loop, the high-pressure CO2 retained in the seal cavity is recovered to a circulating system, the temperature and the pressure of the CO2 in the seal cavity are reduced by virtue of the negative feedback effect of the self-circulation loop, the damage of the high-temperature and high-pressure environment to the dry seal body is improved, the technical requirement and the construction cost of the dynamic seal system of the supercritical fluid power system turbine generator are reduced, and the technical requirement and the construction cost of the seal system are significantly reduced.

Description

Technical Field

[0001] This invention relates to a dynamic sealing device, specifically to a self-circulating dry sealing device for a supercritical carbon dioxide turbine generator. Background Technology

[0002] Dry gas seals are a new type of non-contact sealing technology developed based on gas dynamic bearings. Through the dynamic pressure effect of the fluid in the gap and corresponding auxiliary systems, dry gas seals achieve non-contact operation of the sealing end face. Today, dry gas seals have become the most commonly used dynamic sealing technology in large-scale fluid machinery and process equipment.

[0003] However, although dry gas seals offer better sealing performance, longer service life, and lower vibration disturbance compared to traditional seals such as mechanical / gear seals, the technical requirements and manufacturing costs of seals increase rapidly under harsh operating conditions such as high pressure differentials, high temperatures, and high speeds. This is due to significantly increased technical requirements for component strength (pressure resistance >15MPa), machining precision, and heat resistance (>350℃). Furthermore, the operation of dry gas seals requires real-time flow balancing between the high-pressure continuous external gas source (sealing / isolating gas) and the process gas. Therefore, in addition to the sealing device itself, dry gas seal systems also include numerous instruments, sensors, valve assemblies, and pneumatic gas pressurization equipment, resulting in control cabinets ranging from 1 to 2 meters in size, significantly increasing the overall volumetric footprint of the dry gas seal assembly system.

[0004] For small- to medium-scale applications such as low-power supercritical fluid dynamic cycles, aerospace / underwater weapon power platforms, and mobile high-load compact turbine expanders, traditional dry gas seals not only have a low cost-effectiveness ratio but also cannot meet the special requirements of miniaturization and simplicity of equipment platforms. Therefore, it is necessary to propose a high-efficiency, cost-effective, and highly compact rotary dynamic seal technology that combines new design concepts such as high sealing performance, controllable cost, and miniaturization. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency, cost-effective, and highly compact rotary dynamic seal technology for small and medium-scale special applications such as micro-power supercritical fluid dynamic cycles, aerospace / underwater weapon power platforms, and mobile high-load compact turbine expanders, as well as micro-miniature fluid and turbomachinery, enabling it to be initially applied to confined spaces of 1×1×0.5 meters and below.

[0006] This invention is achieved through the following technical solution:

[0007] A self-circulating dry sealing device for a supercritical carbon dioxide turbine generator includes an impeller assembly, a labyrinth seal ring, a sealing cavity, and a dry gas sealing body.

[0008] The impeller assembly is installed in the volute of the mother machine. The blade ends of the impeller assembly are located at the low-pressure node of the volute. The labyrinth seal and dry gas seal bodies are coaxially sleeved on the impeller assembly and arranged sequentially from the working fluid side to the atmospheric side.

[0009] A sealing cavity is provided between the labyrinth seal ring and the dry gas sealing body. The inlet of the labyrinth seal ring is connected to the rotation gap between the impeller assembly and the volute, and the outlet of the labyrinth seal ring is connected to the sealing cavity. The sealing cavity is connected to the low-pressure node of the mother machine through a circulation pipeline.

[0010] Preferably, the volute is provided with a front exhaust port, one end of which is connected to the sealing cavity, and the other end is connected to the low-pressure node of the mother machine through a circulation pipeline.

[0011] Preferably, the impeller assembly includes an impeller nose cone, a radial impeller, and a main shaft;

[0012] The radial impeller is mounted on the main shaft, the impeller nose cone is located at the end of the main shaft, the impeller nose cone is coaxially connected to the radial impeller, and the labyrinth seal ring and dry gas seal body are mounted on the main shaft.

[0013] Preferably, the labyrinth seal ring is fitted onto the wear-resistant annular gasket, the wear-resistant annular gasket is fitted onto the main shaft, and a bushing is fitted onto the end of the main shaft near the low-pressure side, which can be located at the end of the dry seal body.

[0014] Preferably, the sealing teeth of the labyrinth seal ring are interference-fitted with the wear-resistant annular gasket.

[0015] Preferably, the mother machine is a compressor or a turbine;

[0016] When the mother machine is a compressor, the compressor inlet is designated as the low-pressure node; when the mother machine is a turbine, the turbine outlet is designated as the low-pressure node.

[0017] Preferably, a flow controller is provided on the circulation pipeline.

[0018] Preferably, the dry sealing body includes a dynamic sealing ring assembly, a static sealing ring assembly, a static sealing ring, a dynamic sealing ring, and a loading spring;

[0019] The dynamic sealing ring assembly is sleeved on the main shaft. One end of the dynamic sealing ring assembly is provided with a sealing groove, and the dynamic sealing ring is set in the sealing groove. The static sealing ring assembly is provided with an installation groove, in which the static sealing ring and a loading spring are set. The static sealing ring assembly is loosely sleeved outside the dynamic sealing ring assembly and connected to the turbine generator housing. The end face of the static sealing ring and the end face of the dynamic sealing ring abut against each other. A dynamic pressure groove is provided on the contact surface of the static sealing ring and the dynamic sealing ring.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention provides a self-circulating dry sealing device for a supercritical carbon dioxide turbine generator, used for the dynamic sealing of a high-specific-power, compact supercritical carbon dioxide power system turbine generator set. It includes a labyrinth seal ring, a sealing cavity, and a dry sealing body. The labyrinth seal, as the primary sealing structure of the self-circulating dry sealing device, significantly reduces the pressure of carbon dioxide discharged into the sealing cavity. The dry sealing body is used to suppress carbon dioxide leakage from the sealing cavity to the low-pressure side. The sealing cavity is connected to the low-pressure node of the main unit to form a self-circulating loop. Through the self-circulating loop, not only is the high-pressure CO2 retained in the sealing cavity recovered to the circulation system, but the negative feedback effect of the self-circulating loop also reduces the temperature and pressure of CO2 in the sealing cavity, thereby mitigating the damage to the dry sealing body caused by the high-temperature and high-pressure environment. This significantly reduces the technical requirements and construction costs of the dynamic sealing system for the supercritical fluid power system turbine generator.

[0022] Furthermore, the dry seal body, through the reinforcement and optimization of the dynamic and static ring structures, eliminates the need for external auxiliary air sources and large control and auxiliary systems to operate the seal. This eliminates the complex control system and auxiliary facilities of dry gas seals, significantly reducing the cost of the entire system and improving the cost-effectiveness and market competitiveness of the dynamic seal device. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to the present invention.

[0024] Figure 2 This is a schematic diagram of the dry seal body in a self-circulating dry seal device for a supercritical carbon dioxide turbine generator according to the present invention.

[0025] In the diagram: 1. Labyrinth seal ring, 2. Sealing cavity, 3. Front exhaust port, 4. Wear-resistant annular gasket, 5. Dry seal body, 6. Impeller nose cone, 7. Radial impeller, 8. Flexible coupling, 9. Shaft sleeve, 10. Support kit, 11. Bolt, 12. Inner cartridge plate, 13. Dynamic seal ring assembly, 14. Static seal ring assembly, 15. Dynamic seal ring, 16. Static seal ring, 17. Loading spring. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0027] See Figure 1-2 A self-circulating dry sealing device for a supercritical carbon dioxide turbine generator includes a volute, an impeller assembly, a labyrinth seal ring 1, a sealing cavity 2, a front exhaust port 3, and a dry gas sealing body 5.

[0028] The impeller assembly is installed in the volute of the mother machine. The blade ends of the impeller assembly are located at the low-pressure node of the mother machine volute. The labyrinth seal 1 and the dry gas seal body 5 are coaxially sleeved on the impeller assembly and arranged sequentially from the working fluid side to the atmospheric side. A sealing cavity 2 is provided between the labyrinth seal ring 1 and the dry gas seal body 5. The inlet of the labyrinth seal ring 1 is connected to the rotational gap between the impeller assembly and the volute, and the outlet of the labyrinth seal ring 1 is connected to the sealing cavity 2. The sealing cavity 2 is connected to the low-pressure node of the mother machine through the front exhaust port 3, forming a self-circulation channel for the working fluid.

[0029] The impeller assembly includes an impeller nose cone 6, a radial impeller 7, and a main shaft. The radial impeller 7 is sleeved on the main shaft and connected by a flexible coupling 8. The impeller nose cone 6 is located at the end of the main shaft and is coaxially connected to the radial impeller 7. The wear-resistant annular gasket 4 and the dry seal body 5 are sequentially coaxially sleeved on the main shaft. The wear-resistant annular gasket 4 is located at the end of the radial impeller 7. The labyrinth seal ring 1 is sleeved on the wear-resistant annular gasket 4. The rotation gap is the gap between the radial impeller 7 and the volute. The rotation gap is connected to the inlet of the labyrinth seal ring 1. A bushing 9 is also sleeved at the end of the main shaft near the low-pressure side and can be located at the end of the dry seal body 5.

[0030] The dry sealing body 5 includes an inner manifold 12, a dynamic sealing ring assembly 13, a static sealing ring assembly 14, a static sealing ring 16, a dynamic sealing ring 15, and a loading spring 17. The dynamic sealing ring assembly 13 is mounted on the main shaft via a support kit 10, bolts 11, and the inner manifold 12. One end of the dynamic sealing ring assembly 13 has a first sealing groove. The dynamic sealing ring 15 is installed in the sealing groove via an O-ring. The static sealing ring assembly 14 is fixedly connected to the turbine generator housing and has an installation groove. The static sealing ring 16 and the loading spring 17 are installed in the installation groove. The end of the loading spring 17 has a spring seat that abuts against the static sealing ring 16. The static sealing ring assembly 14 is loosely fitted outside the dynamic sealing ring assembly 13, and the end faces of the static sealing ring 16 and the dynamic sealing ring 15 abut against each other. A dynamic pressure groove is provided on the contact surface of the static sealing ring 16 and the dynamic sealing ring 15. The inner manifold 12 is fixedly connected to the end of the dynamic sealing ring assembly 13 via bolts 11.

[0031] When the dry sealing body 5 is in operation, the dynamic sealing ring 15 rotates at high speed with the turbine generator main shaft under the drive of the dynamic sealing ring assembly 13, while the static sealing ring 16 remains stationary relative to the turbine generator under the constraint of the static sealing ring assembly 14. At this time, the dynamic pressure grooves on the contact surface of the dynamic sealing ring 15 and the static sealing ring 16 form a high-speed relative rotation, which draws the surrounding fluid working medium into the contact surface and causes its pressure to rise significantly, thus slightly lifting the loading spring 17. Finally, a micron-level high-pressure rigid gas film is formed between the contact surface of the dynamic sealing ring 15 and the static sealing ring 16. Under the obstruction of the high-pressure rigid gas film, the leakage path of the fluid working medium from the medium side to the atmosphere side is cut off, thereby realizing the non-contact dynamic sealing function of the dry sealing body.

[0032] The dry seal body does not require external gas sources such as sealing gas and isolation gas for normal operation. Through reinforcement and optimization of the dynamic pressure grooves and ring bodies of the dynamic and static sealing rings, the dry seal body significantly improves its mechanical strength, heat resistance, and wear resistance. It can open and maintain the sealing gap under harsh operating conditions such as dynamic and static interference and idling, eliminating the need for an external auxiliary gas source. Compared to traditional dry gas sealing systems, this eliminates the need for complex control systems and auxiliary facilities.

[0033] The sealing teeth of the labyrinth seal ring 1 form a slight interference fit with the wear-resistant annular gasket. When the unit starts to rotate, the sealing teeth of the labyrinth seal ring adaptively cut a sealing groove with minimal clearance on the inner surface of the annular wear-resistant gasket, significantly improving the sealing performance of the labyrinth seal. The wear-resistant annular gasket is made of metal-based graphite, chromium carbide alloy, or other metallic or non-metallic wear-resistant materials.

[0034] The pre-exhaust port 3 is connected to the low-pressure node of the mother machine through a circulation pipeline to form a self-circulating loop. The self-circulating loop not only recovers the high-pressure carbon dioxide trapped in the sealing cavity 2 to the circulation system, but also significantly reduces the temperature and pressure of carbon dioxide in the sealing cavity due to the negative feedback effect of the self-circulating loop. This improves the damage of the high-temperature and high-pressure environment to the dry seal body and achieves the goal of reducing the technical requirements and construction cost of the turbine generator dry seal system.

[0035] The mother machine is a compressor or a turbine. When the mother machine is a compressor, the front exhaust port 3 is connected to the compressor inlet, and the compressor inlet acts as a low-pressure node of the self-circulating loop. When the mother machine is a turbine, the front exhaust port 3 is connected to the turbine outlet, and the turbine outlet acts as a low-pressure node of the self-circulating loop.

[0036] The self-circulating loop is equipped with a flow controller, which controls the pressure inside the sealed cavity by controlling the return flow of the working fluid, so as to maintain the pressure of the moving parts at a reasonable level.

[0037] Example 1

[0038] The following description uses a supercritical carbon dioxide (CO2) centripetal turbine as an example to illustrate one technical solution of the present invention.

[0039] The dry seal body 5 serves as the main sealing device for a supercritical carbon dioxide centrifugal turbine. It is installed on one side of the impeller of a single-stage cantilever centrifugal compressor (with a labyrinth seal at the front end) for sealing the high-temperature and high-pressure carbon dioxide working fluid, requiring a very small amount of process gas to leak into the atmosphere.

[0040] The front exhaust port is connected to the outlet of the radial turbine. After the sealing airflow passes through the two-stage front carbon ring of the dry seal body, it mixes with the high-temperature fluid (pressure greater than 11.5MPa, temperature about 450℃) leaking from the radial turbine. Under the action of pressure difference, it automatically flows back to the outlet pipeline of the radial turbine through the front exhaust port (without the need for external pump assistance).

[0041] The dry-type sealing body rotates bidirectionally and is used in supercritical carbon dioxide centrifugal turbines. The process gas is high-temperature, high-pressure supercritical carbon dioxide leaking from the moving and stationary gaps of the centrifugal turbine (throttled through a labyrinth seal). The process gas pressure is greater than 11.5 MPa, and the process gas temperature can reach up to 500℃.

[0042] Before the turbine unit starts receiving air, close the inlet and outlet valves of the turbine / compressor. Use the booster pump and self-regulating pressure reducing valve to increase the internal pressure of the turbine / compressor to 7.8 MPa. Note that when pressurizing the compressor unit, the pressure difference between the sealing gas inlet pressure (pressure before the carbon ring) and the internal pressure of the unit (pressure after the carbon ring) should ideally not exceed 1 MPa. The pressure should be increased slowly during the intake process. Once the unit reaches standard operating conditions, the pressure gauge will display approximately 8.5 MPa after the first-stage pressure reduction. The pressure gauge will also display the sealing chamber pressure, and the differential pressure sensor will monitor for any abnormalities such as filter blockage.

[0043] The pre-exhaust port is connected to the low-pressure nodes at the inlet and outlet of the turbine generator, forming a self-circulating loop. This self-circulating loop not only recovers the high-pressure CO2 retained in the sealed cavity into the circulation system, but also reduces the temperature and pressure of CO2 within the sealed cavity through negative feedback. This mitigates the damage to the dry seal body caused by the high-temperature and high-pressure environment, reducing the technical requirements and construction costs of the dynamic sealing system for the supercritical fluid power system turbine generator. Furthermore, because the device uses a dry seal, it eliminates the need for external auxiliary gas sources such as sealing / isolation gases and large control and auxiliary systems, significantly reducing the overall system cost. This improves the cost-effectiveness and market competitiveness of the dynamic sealing device.

[0044] This invention employs a dry-type sealing body, which, compared to traditional dry gas sealing devices, eliminates the need for a high-pressure, continuous external auxiliary gas source such as sealing gas. Therefore, real-time flow balancing between the auxiliary gas source and process gas is unnecessary, allowing for the reduction of numerous instruments, valves, control components, and auxiliary facilities required for dry gas sealing. This significantly reduces the volumetric footprint and weight of the dynamic sealing system, resulting in a substantial increase in compactness, enabling its application in confined spaces of 1×1×0.5 meters or less. Thus, this invention provides a cost-effective and highly compact rotary dynamic sealing technology for small-to-medium-scale special applications such as micro-power supercritical fluid dynamic cycles, aerospace / underwater weapon power platforms, and mobile high-load compact turbine expanders, as well as for micro-miniature fluid and turbomachinery.

[0045] This invention, by employing a self-circulating loop and a dry sealing design, reduces the damage to the sealing component caused by high-temperature, high-pressure supercritical fluids. It lowers the technical requirements and construction costs of the dynamic sealing system for supercritical carbon dioxide turbine generators, and eliminates the complex auxiliary equipment and control systems of traditional dry gas sealing devices. This increases the cost-effectiveness and compactness of dynamic sealing technology in small- to medium-scale applications, enabling the sealing device to be widely used in space-constrained, intermittent, deep-space / deep-sea, and extreme conditions and special scenarios with minimal sealing loss. Therefore, this invention provides a high-efficiency, cost-effective, and compact rotary dynamic sealing technology for small- to medium-scale special applications such as micro-power supercritical fluid power cycles, aerospace / underwater weapon power platforms, and mobile high-load compact turbine expanders, as well as for micro-fluid and turbomachinery. Simultaneously, this invention also expands the application scenarios and technological competitiveness of dynamic sealing technology.

[0046] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A self-circulating dry sealing device for a supercritical carbon dioxide turbine generator, characterized in that, It includes an impeller assembly, a labyrinth seal (1), a sealing cavity (2), and a dry seal body (5); The impeller assembly is installed in the volute of the mother machine. The blade end of the impeller assembly is located at the low-pressure node of the volute. The labyrinth seal ring (1) and the dry seal body (5) are coaxially sleeved on the impeller assembly and arranged sequentially from the working fluid side to the atmospheric side. A sealing cavity (2) is provided between the labyrinth sealing ring (1) and the dry sealing body (5). The inlet of the labyrinth sealing ring (1) is connected to the rotation gap between the impeller assembly and the volute. The outlet of the labyrinth sealing ring (1) is connected to the sealing cavity (2). The sealing cavity (2) is connected to the low-pressure node of the mother machine through a circulation pipeline. The volute is provided with a front exhaust port (3), one end of which is connected to the sealing cavity, and the other end is connected to the low-pressure node of the mother machine through a circulation pipeline; The dry sealing body (5) includes a dynamic sealing ring assembly (13), a static sealing ring assembly (14), a static sealing ring (16), a dynamic sealing ring (15), and a loading spring (17). The dynamic sealing ring assembly (13) is sleeved on the main shaft. One end of the dynamic sealing ring assembly (13) is provided with a sealing groove. The dynamic sealing ring (15) is set in the sealing groove. The static sealing ring assembly (14) is provided with an installation groove. The static sealing ring (16) and a loading spring are set in the installation groove. The static sealing ring assembly (14) is loosely sleeved outside the dynamic sealing ring assembly (13) and connected to the turbine generator housing. The end face of the static sealing ring (16) and the end face of the dynamic sealing ring (15) abut against each other. A dynamic pressure groove is provided on the contact surface of the static sealing ring (16) and the dynamic sealing ring (15). The sealing teeth of the labyrinth seal ring (1) and the wear-resistant annular gasket form an interference fit relationship. When the unit starts to rotate, the sealing teeth of the labyrinth seal ring adaptively cut a sealing groove with a minimum gap on the inner surface of the annular wear-resistant gasket, thereby improving the sealing performance of the labyrinth seal.

2. The self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to claim 1, characterized in that, The impeller assembly includes an impeller nose cone (6), a radial impeller (7), and a main shaft; The radial impeller (7) is fitted on the main shaft, the impeller nose cone (6) is set at the end of the main shaft, the impeller nose cone (6) is coaxially connected with the radial impeller (7), and the labyrinth seal ring (1) and the dry seal body (5) are fitted on the main shaft.

3. The self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to claim 2, characterized in that, The labyrinth seal (1) is fitted on the wear-resistant annular gasket (4), which is fitted on the main shaft. The end of the main shaft near the low-pressure side is also fitted with a bushing (9) and can be located at the end of the dry seal body (5).

4. The self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to claim 3, characterized in that, The sealing teeth of the labyrinth seal ring (1) are interference-fitted with the wear-resistant annular gasket (4).

5. The self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to claim 1, characterized in that, The machine is a compressor or a turbine; When the mother machine is a compressor, the compressor inlet is designated as the low-pressure node; when the mother machine is a turbine, the turbine outlet is designated as the low-pressure node.

6. The self-circulating dry sealing device for a supercritical carbon dioxide turbine generator according to claim 1, characterized in that, A flow controller is installed on the circulation pipeline.

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