An independently-operable combined cycle unit seal oil system

Abstract

The present application relates to the field of generator set lubrication, in particular to a kind of independently operated combined cycle unit seal oil system;The lubricating oil tank is located in the first height layer, the vacuum oil tank is located in the second height layer lower than the first height layer, the oil inlet of the seal oil system is communicated with the oil supply port of the vacuum oil tank, the oil return port of seal oil system is communicated with lubricating oil tank, it further includes: bypass pipeline, one end of the bypass pipeline is communicated with the lubricating oil tank accident oil discharge pipeline, the other end is communicated with the oil return port of the vacuum oil tank;Flow regulating valve, it is installed on the bypass pipeline, for controlling the on-off of the bypass pipeline and adjusting the oil flow in bypass pipeline.The present application realizes the independent operation of seal oil system, eliminates the dependence on lubricating oil system, while realizing zero energy consumption passive oil supply and blocking the pollution cycle between systems.

Description

Technical Field

[0001] This invention relates to the field of generator set lubrication, and more specifically to a sealing oil system for a combined cycle generator set that can operate independently. Background Technology

[0002] In modern power systems, hydrogen sealing oil systems, as supporting facilities for large hydrogen-cooled generator sets, play a crucial role in efficiently cooling and preventing hydrogen leakage, and are an important foundation for ensuring the safe and efficient operation of generator sets.

[0003] Existing sealing oil systems mainly rely on the lubrication oil system to supply oil and maintain the oil level, thus forming a two-way oil circuit interaction.

[0004] In current technology, the sealing oil system and the lubrication oil system operate in a tightly coupled manner. Under normal operating conditions, the lubrication oil system continuously supplies the sealing oil system with a basic oil source through the oil circuit and maintains its oil level stability, ensuring the normal operation of the sealing oil circulation. Simultaneously, the hydrogen-side drained oil from the sealing oil system is partially reinjected into the lubrication oil system after being treated in the circulating oil tank, forming a bidirectional oil circuit interaction between the two systems. When the sealing oil system needs to be shut down for maintenance, the generator must be switched to cold standby or maintenance mode, and the internal hydrogen must be purged and replaced before proceeding.

[0005] However, the above operating mode has the following problems in practical applications. First, when the lubricating oil system needs to be shut down for emergency repairs due to sudden situations such as oil pump failure, filter blockage, or pipeline rupture, the sealing oil system cannot be shut down simultaneously. Once the lubricating oil supply is cut off, the sealing oil system will experience a sudden pressure drop due to the loss of oil source, potentially leading to safety accidents such as hydrogen leakage or even explosion inside the generator. Second, the bidirectional oil circuit interaction creates a contamination cycle, meaning that contaminants from the lubricating oil system will enter the sealing oil system through the oil circuit replenishment, and the hydrides or moisture carried by the hydrogen from contact with the hydrogen in the sealing oil system will also cause lubricating oil deterioration after reinjection. In addition, the above system requires highly skilled operators; misoperation may cause serious consequences such as a sudden drop in sealing oil pressure, threatening the safe operation of the unit. Summary of the Invention

[0006] In view of the problems mentioned in the prior art, the present invention proposes a sealing oil system for a combined cycle unit that can operate independently, so as to solve the problems in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention proposes a sealing oil system for a combined cycle power unit that can operate independently, comprising a lubricating oil tank, a vacuum oil tank, and a sealing oil system. The lubricating oil tank is located at a first height level, and the vacuum oil tank is located at a second height level below the first height level. The oil inlet of the sealing oil system is connected to the oil supply port of the vacuum oil tank, and the oil return port of the sealing oil system is connected to the lubricating oil tank. The system also includes: A bypass pipeline, one end of which is connected to the emergency drain pipeline of the lubricating oil tank, and the other end of which is connected to the return oil port of the vacuum oil tank. A flow regulating valve is installed on the bypass pipeline to control the opening and closing of the bypass pipeline and to regulate the flow rate of oil in the bypass pipeline. Under the combined effect of gravitational potential energy generated by the vertical height difference between the lubricating oil tank and the vacuum oil tank, and the negative pressure suction of the vacuum oil tank, the oil in the lubricating oil tank is transported to the vacuum oil tank through the bypass pipe, and then returns to the lubricating oil tank after passing through the sealing oil system, forming a circulation loop independent of the lubricating oil system.

[0008] As a further improvement of the present invention, a vacuum compression device is connected to the top of the vacuum oil tank. The vacuum compression device is used to maintain the vacuum level inside the vacuum oil tank and provide negative pressure suction power.

[0009] As a further improvement of the present invention, the flow regulating valve is a steel shut-off valve, which is located at one end of the bypass pipeline near the emergency drain line interface of the lubricating oil tank.

[0010] As a further improvement of the present invention, the diameter of the bypass pipe is matched with the diameter of the emergency drain pipe of the lubricating oil tank, and the pressure rating of the bypass pipe is matched with the working pressure of the sealing oil system.

[0011] As a further improvement of the present invention, the opening of the flow regulating valve is configured such that the replenishment flow rate in the bypass pipeline is dynamically balanced with the oil loss of the sealing oil system, so as to maintain a constant liquid level in the vacuum oil tank.

[0012] As a further improvement of the present invention, it also includes an online oil filtration device, which is located on the return oil pipeline between the return oil port of the sealing oil system and the lubricating oil tank, and is used to filter and purify the oil returning to the lubricating oil tank.

[0013] As a further improvement of the present invention, the emergency drain pipeline is also provided with an isolation valve, and the oil inlet end of the bypass pipeline is connected to the upstream side of the isolation valve; When the isolation valve is closed, the lubricating oil tank, bypass pipeline, vacuum oil tank, and sealing oil system form an independent circulation loop.

[0014] As a further improvement of the present invention, the bypass pipe is made of seamless steel pipe.

[0015] As a further improvement of the present invention, the height of the first height layer is 6.5m and the height of the second height layer is 1.5m.

[0016] As a further improvement of the present invention, it also includes an operation and maintenance platform, which is located at the installation position of the flow regulating valve.

[0017] Compared with the prior art, the present invention achieves the following technical effects: This invention connects the emergency drain line of the lubricating oil tank directly to the return port of the vacuum oil tank via a bypass pipeline, and uses a flow regulating valve to control the replenishment flow, thus providing the sealing oil system with an independent replenishment channel separate from the normal oil supply path of the lubricating oil system. Even if the lubricating oil system is cut off due to emergencies such as pump failure, filter blockage, or pipe rupture, the sealing oil system can still obtain a stable oil supply through an independent circuit, maintaining the sealing oil pressure and eliminating the risk of hydrogen leakage and secondary safety accidents caused by system coupling.

[0018] This invention utilizes the inherent spatial layout of the field equipment, placing the lubricating oil tank at a high position and the vacuum oil tank at a low position, leveraging the vertical height difference between the two to create gravitational potential energy. Simultaneously, the vacuum oil tank maintains a negative pressure state to create suction force. Driven by the combined gravitational potential energy and negative pressure suction force, the oil can flow by gravity through the bypass pipeline to the vacuum oil tank without any external power pump, achieving zero-energy passive oil supply, significantly reducing system operating power consumption and equipment complexity. In addition, the circulation loop constructed by this invention achieves physical isolation through the bypass pipeline and flow regulating valve, eliminating the oil circuit interaction channel for normal operation and replenishment between the two systems. Contaminants cannot spread, fundamentally eliminating the conditions for the formation of contamination circulation, and ensuring the oil quality and component operating performance and service life between the systems. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Reference numerals in the attached diagram: 1. Lubricating oil tank; 2. Vacuum oil tank; 3. Bypass pipeline; 4. Flow regulating valve; 5. Online oil filter device; 6. Sealing oil system. Detailed Implementation

[0021] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] See Figure 1 This embodiment proposes an independently operable sealing oil system for a combined cycle power unit, including a lubricating oil tank 1, a vacuum oil tank 2, and a sealing oil system 6. The lubricating oil tank 1 is located at a first height level, and the vacuum oil tank 2 is located at a second height level below the first height level. The oil inlet of the sealing oil system 6 is connected to the oil supply port of the vacuum oil tank 2, and the oil return port of the sealing oil system 6 is connected to the lubricating oil tank 1. The system also includes: Bypass pipe 3, one end of which is connected to the emergency drain pipe of the lubricating oil tank 1, and the other end is connected to the return port of the vacuum oil tank 2; A flow regulating valve 4 is installed on the bypass pipe 3 and is used to control the opening and closing of the bypass pipe 3 and regulate the oil flow rate in the bypass pipe 3. Under the combined effect of the gravitational potential energy generated by the vertical height difference between the lubricating oil tank 1 and the vacuum oil tank 2, and the negative pressure suction of the vacuum oil tank 2, the oil in the lubricating oil tank 1 is transported to the vacuum oil tank 2 through the bypass pipe 3, and then returns to the lubricating oil tank 1 after passing through the sealing oil system 6, forming a circulation loop independent of the lubricating oil system.

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] like Figure 1As shown, the system in this embodiment includes a lubricating oil tank 1, a vacuum oil tank 2, a sealing oil system 6, a bypass pipeline 3, and a flow regulating valve 4. The lubricating oil tank 1 is located on the first height level of the generator plant, while the vacuum oil tank 2 is located on a second height level below the first height level. In this embodiment, the lubricating oil tank 1 is located at 6.5m, and the vacuum oil tank 2 is located at 1.5m, forming a vertical height difference of approximately 5m between them.

[0033] The sealing oil system 6 in this embodiment is an existing component of the generator set. Internally, it includes sealing tiles, a hydrogen-side oil circuit, and an air-side oil circuit distributor. The oil inlet of the sealing oil system 6 is connected to the oil supply port of the vacuum oil tank 2 via an oil supply pipeline, and the oil return port of the sealing oil system 6 is connected to the lubricating oil tank 1 via a return pipeline. One end of the bypass pipeline 3 is connected to the emergency drain pipeline of the lubricating oil tank 1, and the other end is connected to the oil return port at the top of the vacuum oil tank 2. A flow regulating valve 4 is installed on the bypass pipeline 3. Under the influence of its own gravity and the negative pressure inside the vacuum oil tank 2, the oil in the lubricating oil tank 1 flows into the vacuum oil tank 2 through the bypass pipeline 3, and then is supplied to the sealing oil system 6 from the oil supply port of the vacuum oil tank 2. The oil returning after passing through the sealing oil system 6 finally returns to the lubricating oil tank 1, forming a complete circulation loop independent of the original oil supply path of the lubricating oil system.

[0034] The specific structure of each component and their interconnections will be further described below.

[0035] In this embodiment, the lubricating oil tank 1 has a sealed steel structure under normal pressure, and integrates supporting lubrication components such as an emergency lubricating oil pump and multiple AC lubricating oil pumps. The side walls are equipped with multiple oil circuit interfaces, including an emergency drain line, a lubricating oil return line, and a replenishment line. An isolation valve is installed on the emergency drain line to control the opening and closing of the emergency drain passage. In this embodiment, the bypass pipe 3 is connected upstream of the isolation valve, ensuring that the bypass pipe 3 can still draw oil from the lubricating oil tank normally when the isolation valve is closed. The lubricating oil tank 1 stores turbine oil, serving as the oil source for the entire independent sealing oil circulation loop, and also receives the return oil from the sealing oil system 6, maintaining the total oil volume balance in the circulation loop.

[0036] In this embodiment, the vacuum oil tank 2 is located at a second height level, below the first height level, with an installation elevation of 1.5m. This creates a 5m vertical height difference with the higher-positioned lubricating oil tank 1, providing potential energy for the gravity-driven flow of the oil. The top interface of the vacuum oil tank 2 is connected to a vacuum compression device. During normal operation, the vacuum compression device continuously extracts gas from inside the vacuum oil tank 2, maintaining a stable negative pressure vacuum inside the tank. This serves two purposes: firstly, it degasses the oil entering the tank, removing any gas and moisture mixed in; secondly, it provides continuous negative pressure suction power to the bypass pipe 3, working in conjunction with gravitational potential energy to drive the oil flow. The bottom of the vacuum oil tank 2 is equipped with an oil supply port and an oil return port. The oil supply port is located on the side of the bottom of the oil tank and is connected to the oil inlet of the sealing oil system 6 through the oil supply pipeline. It is used to supply the sealing oil system 6 with a stable pressure. The oil return port is located on the other side of the bottom of the oil tank and is directly connected to the oil outlet of the bypass pipeline 3. This allows the oil replenished by the bypass pipeline 3 to directly enter the vacuum oil tank 2. After being treated by negative pressure degassing and pressure stabilization, it enters the oil supply stage, ensuring that the replenished oil does not affect the oil supply stability of the sealing oil.

[0037] In this embodiment, the bypass pipe 3 is preferably made of oil-resistant seamless steel pipe. The pressure rating of the pipe material is fully matched with the maximum working pressure of the sealing oil system 6. The pipe diameter is consistent with the pipe diameter of the emergency drain pipe of the lubricating oil tank (1) to ensure that the flow capacity of the oil can meet the maximum oil replenishment requirements of the system. The oil inlet of the bypass pipe 3 is connected to the upstream side of the isolation valve on the emergency drain pipe of the lubricating oil tank 1 through a flange connection. The oil outlet is also connected to the return port of the vacuum oil tank 2 through a flange connection. The flange connection not only ensures the sealing performance of the pipe interface, but also facilitates the later maintenance, disassembly and modification of the pipe. In terms of pipeline routing, the bypass pipeline 3 is led out from the emergency drain port of the lubricating oil tank (1), and is first raised to avoid the strong vibration area where the turbine body is located and the surrounding high-temperature steam pipelines. This avoids the vibration fatigue of the unit during long-term operation from affecting the sealing of the pipeline connection and ensures the stability of the physical and chemical properties of the oil. After being raised, the pipeline extends horizontally along the fixed support frame of the unit until it reaches the position above the vacuum oil tank 2, and then bends downwards gently, finally connecting to the return port of the vacuum oil tank 2. The entire pipeline routing is fixedly installed based on the existing equipment frame on site, without the need to add a large support structure. The modification cost is low and the impact on the original layout on site is minimal. At the same time, the pipeline maintains a smooth slope design throughout, without any dead corners where oil accumulates locally, ensuring that the oil can flow smoothly and continuously in the pipeline without problems such as oil accumulation or air lock.

[0038] In this embodiment, the flow regulating valve 4 is installed at the emergency drain port of the bypass pipeline 3 near the lubricating oil tank 1. It is preferably a steel shut-off valve. The pressure rating of the flow regulating valve 4 is consistent with the pressure bearing standard of the bypass pipeline 3, and its diameter matches the pipeline diameter. It has the functions of pipeline opening and closing and flow regulation, and the replenishment oil flow in the bypass pipeline 3 can be precisely controlled by adjusting the valve opening. In addition to the flow regulating valve 4, the bypass pipeline 3 in this embodiment also has a bypass isolation gate valve. The bypass isolation gate valve can serve as an emergency backup path. When the flow regulating valve 4 malfunctions, becomes stuck, or needs disassembly and repair, the system can be temporarily switched to the bypass isolation gate valve to control the oil circuit, ensuring that the replenishment path is not interrupted, effectively improving the redundancy and reliability of the system operation.

[0039] A dedicated operation and maintenance platform is also set up at the valve installation location. The installation height of the operation and maintenance platform is adapted to the operation needs of operation and maintenance personnel. It not only facilitates the daily adjustment of valve opening and inspection of pipeline operation status by the operators, but also provides a safe and stable operating space for valve maintenance and replacement operations.

[0040] The online oil filter device 5 is located on the return oil pipeline between the return oil port of the sealing oil system 6 and the lubricating oil tank 1. When the return oil of the sealing oil system 6 completes the sealing operation, it first passes through the multi-stage filtration and purification of the online oil filter device (5) to remove metal particles, water and solid impurities mixed in the oil before returning to the lubricating oil tank 1. This ensures that the oil quality in the entire independent circulation loop meets the unit operation standards and prevents impurities from entering the vacuum oil tank 2 and the generator sealing tile components with the oil circuit, affecting the hydrogen sealing performance.

[0041] The oil inlet of the sealing oil system 6 is connected to the oil supply port of the vacuum oil tank 2 via an oil supply pipeline. It receives the pressure-stabilizing sealing oil output from the vacuum oil tank 2 and delivers it to the sealing tiles of the generator, forming a stable oil film barrier between the sealing tiles and the shaft. This ensures reliable sealing of the hydrogen inside the generator and prevents hydrogen leakage. The hydrogen-side return port of the sealing oil system 6 is connected to the lubricating oil tank 1 via a return oil pipeline. After the sealing operation is completed, the oil is delivered to the online oil filter device 5 via the return oil pipeline. After filtration and purification, it flows back to the lubricating oil tank 1, completing the return cycle of the entire system.

[0042] In this embodiment, the oil circuit of the independent circulation loop is arranged as follows: lubricating oil tank 1, emergency drain line, bypass line 3, vacuum oil tank 2 return port, vacuum oil tank 2, sealing oil system 6, online oil filter device 5, and lubricating oil tank 1, forming a complete closed oil circulation path. When the isolation valve on the emergency drain line of lubricating oil tank 1 is closed, this circulation path is completely disconnected from the bearing lubrication branch and oil purification branch of the lubricating oil system, and there is no oil circuit interaction, thereby realizing the completely independent operation of the sealing oil system, which no longer depends on the oil supply of the lubricating oil system.

[0043] In the specific implementation process, a comprehensive system survey and parameter collection were first carried out for the target unit. The actual installation height difference between the lubricating oil tank 1 and the vacuum oil tank 2 was confirmed through on-site measurement, verifying the basic conditions for gravity-driven flow. The pipe diameter, interface type and pressure rating of the original emergency drain pipeline were checked to confirm that the newly added bypass pipeline 3 could be directly adapted and installed with the original pipeline. Long-term operation monitoring data of the vacuum oil tank 2 were retrieved to confirm the long-term stability of the vacuum degree and verify the reliability of the negative pressure suction power. At the same time, the oil in use in the system was sampled and tested to obtain the physical and chemical parameters such as the density and viscosity of the oil, providing accurate basic data support for subsequent pipeline flow calculation and resistance calculation.

[0044] After completing parameter acquisition, the design and fluid dynamics verification of bypass pipeline 3 were carried out. The theoretical oil replenishment flow rate of bypass pipeline 3 was calculated to confirm that its value can cover the maximum oil replenishment demand of sealing oil system 6 and meet the oil replenishment requirements of system operation. At the same time, the frictional resistance and local resistance loss along the bypass pipeline 3 were calculated to verify that the total driving energy composed of gravitational potential energy and negative pressure suction force is greater than the total resistance loss during pipeline flow, ensuring that stable oil replenishment can be achieved without the need for additional power equipment such as oil replenishment pumps.

[0045] After design verification, on-site installation was carried out. First, a bypass connection point was selected on the emergency drain line of lubricating oil tank 1. The connection point was located upstream of the isolation valve, and bypass pipeline 3 was led out using a flange connection. Bypass pipeline 3 was laid according to the pre-planned path. Then, a flow regulating valve 4 and a parallel bypass isolation gate valve were installed near the end of bypass pipeline 3, and an operation and maintenance platform was built simultaneously. Finally, the other end of bypass pipeline 3 was connected to the return port of vacuum oil tank 2, completing the connection and installation of all pipelines. After all installation work was completed, a sealing pressure test was conducted on all welds and flange connections to eliminate potential leakage risks and confirm that all components could function normally.

[0046] First, a continuity test is conducted. The operator stands on the operation and maintenance platform and opens the flow regulating valve 4, allowing the oil in the lubricating oil tank 1 to gradually flow into the bypass pipe 3. Throughout the process, the flow of oil in the pipe and the changes in the liquid level in the vacuum oil tank 2 are observed to confirm that there are no blockages or leaks in the pipe and that the oil can flow smoothly into the cavity of the vacuum oil tank 2, verifying that the oil replenishment path is functioning normally. After the continuity verification is completed, flow balance adjustment is performed. Based on the actual oil loss during the operation of the sealing oil system 6, the opening of the flow regulating valve 4 is gradually fine-tuned to achieve a dynamic balance between the amount of oil replenished in the bypass pipe 3 and the amount of oil lost by the system. This keeps the liquid level in the vacuum oil tank 2 stable within the standard operating range, ensuring that the oil supply pressure of the sealing oil system 6 remains stable and meets the generator sealing requirements.

[0047] Subsequently, system independence verification was conducted. The isolation valve on the emergency drain line of lubricating oil tank 1 was closed, leaving only the bypass replenishment line operational. The oil circulation path was continuously monitored to confirm that the oil flowed entirely along the independent closed-loop circuit. Simultaneously, an ultrasonic leak detector was used to inspect all sealing points, including flange connections, to verify the reliable sealing performance of the circuit. After completing all verification items, the system can officially enter independent standby mode. When the lubricating oil system requires emergency shutdown for maintenance due to a malfunction, simply closing the isolation valve allows the sealing oil system 6 to continue operating stably via the independent circulation circuit.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0049] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. 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 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 sealing oil system for a combined cycle power unit that can operate independently, characterized in that, The system includes a lubricating oil tank (1), a vacuum oil tank (2), and a sealing oil system (6). The lubricating oil tank (1) is located at a first height level, and the vacuum oil tank (2) is located at a second height level below the first height level. The oil inlet of the sealing oil system (6) is connected to the oil supply port of the vacuum oil tank (2), and the oil return port of the sealing oil system (6) is connected to the lubricating oil tank (1). The system also includes: Bypass pipe (3), one end of which is connected to the emergency drain pipe of the lubricating oil tank (1), and the other end is connected to the return port of the vacuum oil tank (2); A flow regulating valve (4) is installed on the bypass pipe (3) to control the opening and closing of the bypass pipe (3) and to regulate the oil flow rate in the bypass pipe (3); Under the combined effect of the gravitational potential energy generated by the vertical height difference between the lubricating oil tank (1) and the vacuum oil tank (2) and the negative pressure suction of the vacuum oil tank (2), the oil in the lubricating oil tank (1) is transported to the vacuum oil tank (2) through the bypass pipe (3), and then returns to the lubricating oil tank (1) after passing through the sealing oil system (6), forming a circulation loop independent of the lubricating oil system.

2. The independently operable sealing oil system for a combined cycle power unit according to claim 1, characterized in that, The top of the vacuum oil tank (2) is connected to a vacuum compression device, which is used to maintain the vacuum level inside the vacuum oil tank (2) and provide negative pressure suction power.

3. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, The flow regulating valve (4) is a steel shut-off valve, located at one end of the bypass pipeline (3) near the emergency drain line interface of the lubricating oil tank (1).

4. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, The diameter of the bypass pipe (3) is matched with the diameter of the emergency drain pipe of the lubricating oil tank (1), and the pressure rating of the bypass pipe (3) is matched with the working pressure of the sealing oil system (6).

5. The independently operable sealing oil system for a combined cycle power unit according to claim 1, characterized in that, The opening of the flow regulating valve (4) is configured such that the replenishment flow rate in the bypass pipeline (3) is dynamically balanced with the oil loss of the sealing oil system (6) in order to maintain a constant liquid level in the vacuum oil tank (2).

6. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, It also includes an online oil filter device (5), which is located on the return oil pipeline between the return oil port of the sealing oil system (6) and the lubricating oil tank (1) for filtering and purifying the oil returning to the lubricating oil tank (1).

7. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, An isolation valve is also provided on the accident drain pipeline, and the oil inlet end of the bypass pipeline (3) is connected to the upstream side of the isolation valve; When the isolation valve is closed, the lubricating oil tank (1), the bypass pipeline (3), the vacuum oil tank (2), and the sealing oil system (6) form an independent circulation loop.

8. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, The bypass pipeline (3) is made of seamless steel pipe.

9. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, The height of the first height layer is 6.5m, and the height of the second height layer is 1.5m.

10. The independently operable sealing oil system for a combined cycle unit according to claim 1, characterized in that, It also includes an operation and maintenance platform, which is located at the installation position of the flow regulating valve (4).

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