A small turbine speed closing valve oil line pressure stabilizing sudden closing prevention system

Abstract

The application discloses a small steam turbine speed closing valve oil path stable pressure burst closing prevention system and relates to the technical field of small steam turbine hydraulic control. The system comprises a small machine lubricating oil tank, an oil pump, a main oil channel and an original accumulator group connected to the main oil channel. The first oil outlet is connected with the lubricating oil supply pipeline, and the second oil outlet is connected with the small machine adjusting oil supply pipeline. The adjusting oil filter is arranged on the small machine adjusting oil supply pipeline. The oil outlet side of the adjusting oil filter is connected with a new accumulator group. The oil outlet of the new accumulator group is only communicated with the pipe section between the oil outlet side of the adjusting oil filter and the small machine adjusting oil system to independently supply oil to the small machine adjusting oil system. The application adds the new accumulator group for the end of the adjusting oil path downstream of the adjusting oil filter to realize the independent stable pressure of the lubricating oil path and the adjusting oil path, greatly shortens the oil supply path, avoids the lubricating oil path shunting, and effectively prevents the abnormal burst closing of the speed closing valve.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology for small steam turbines, specifically to a pressure stabilization and anti-sudden shutdown system for the oil circuit of a small steam turbine's fast-closing valve. Background Technology

[0002] Small steam turbines (hereinafter referred to as small turbines) are the driving equipment for important auxiliary machines such as feedwater pumps and induced draft fans in thermal power units. Their operational reliability is directly related to the unit's load-bearing capacity and safety stability. The quick-closing valve, as the main steam inlet valve for the small turbine, adopts the control principle of "opening under pressure and closing under pressure," relying on regulating oil pressure to overcome spring force to maintain its open state. When the regulating oil pressure momentarily drops to the closing threshold, the quick-closing valve immediately closes, forcing the small turbine to trip or trip, leading to a series of serious consequences such as the shutdown of the steam-driven feedwater pump or induced draft fan, a sudden drop in unit feedwater flow or a sharp reduction in induced draft capacity, and a forced rapid reduction in load. During unit operation, when the oil system operating conditions change, such as during lubricating oil pump switching or quick-closing valve operation tests, the instantaneous fluctuation of regulating oil pressure is the main cause of the quick-closing valve's sudden closure. Through on-site investigation and literature review, multiple power plants have found that the quick-closing valves of similar small turbines in Hangzhou Steam Turbine Plant have experienced the problem of sudden closure due to unstable quick-closing oil pressure during changes in operating conditions, a common and long-standing problem for this type of equipment.

[0003] Currently, small engine oil systems are typically equipped with accumulators to stabilize oil supply pressure. For example, Chinese utility model patent CN2864183Y discloses a turbine oil supply system in which an accumulator group is connected to the main oil pump outlet's oil supply header to meet the instantaneous high-flow-rate oil supply demands such as the rapid shut-off action of the hydraulic actuator. This solution, and the conventional practice of existing small engine oil systems, involves directly connecting the accumulator group to the main oil supply header, with one accumulator group simultaneously supplying oil to both the lubrication and regulating oil circuits. However, in the specific application scenarios of small steam turbines, since the regulating oil and lubrication oil share a single oil pump supply network, and the main oil channel has lubrication oil inlets and regulating oil inlets sequentially along the oil flow direction, the aforementioned solution of placing a single accumulator group at the very upstream of the main oil channel has the following two structural defects: Firstly, the original accumulator is far from the quick-closing valve body, with multiple components such as the regulating oil filter in between, resulting in high pipeline pressure loss. The pressure oil released by the accumulator has to go through a long path and multiple resistance elements before reaching the quick-closing valve, which leads to response delay and reduced compensation effect, making it impossible to achieve rapid and accurate pressure replenishment during the transient process of pressure fluctuation.

[0004] Secondly, the original accumulator needed to simultaneously supply and stabilize the oil pressure of both the lubrication and regulating oil circuits, and its capacity and release flow rate were designed based on the combined operating conditions of both circuits. Since the lubrication oil inlet is located before the regulating oil inlet, during fluctuations in operating conditions, most of the oil volume and pressure released instantaneously by the original accumulator is preferentially consumed by the pre-positioned lubrication oil branch. The instantaneous compensation flow rate obtained by the regulating oil circuit is severely diverted, making it difficult to meet the regulating oil pressure and volume required to maintain the opening of the quick-closing valve. Especially during conditions such as lubrication pump switching, the compensating capacity of the regulating oil circuit is severely insufficient when the system pressure drops instantaneously.

[0005] The aforementioned reasons prevent the single accumulator group located upstream of the main oil passage in existing small oil systems from effectively ensuring the stability of the regulating oil pressure of the quick-closing valve when operating conditions change. Current industry analyses primarily focus on factors such as insufficient accumulator bladder pressure, excessively long oil stop time for thermal control logic, and internal leakage in the quick-closing valve cylinder. The ultimate solutions are merely preventative maintenance or avoiding quick-closing valve operation tests during operation, failing to fundamentally solve the problem of sudden valve closure caused by defects in the oil circuit topology.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: This invention provides a pressure stabilization and anti-sudden shutdown system for the oil circuit of a small steam turbine's fast-closing valve, comprising a small turbine lubricating oil tank, an oil pump, a main oil passage, and a primary accumulator group connected to the main oil passage; The main oil channel is provided with a first oil inlet and a second oil inlet in sequence along the oil flow direction. The first oil inlet is connected to a lubricating oil supply pipeline, and the second oil inlet is connected to a small engine regulating oil supply pipeline. The outlet end of the small machine regulating oil supply pipeline is used to connect to the small machine regulating oil system, and the small machine regulating oil supply pipeline is equipped with a regulating oil filter. The oil outlet side of the regulating oil filter is connected to a new accumulator group. The oil outlet of the new accumulator group is only connected to the section of the small turbine regulating oil supply pipeline located between the oil outlet side of the regulating oil filter and the small turbine regulating oil system, so as to independently supply oil to the small turbine regulating oil system.

[0007] The original accumulator group is located on the main oil channel and in the upstream area of ​​the first oil intake.

[0008] The lubricating oil supply pipeline is provided with a lubricating oil cooler group and a lubricating oil filter group in sequence along the oil flow direction. The oil outlet of the lubricating oil filter group is connected to each lubricating oil terminal through pipelines.

[0009] The regulating oil filter and the lubricating oil filter group are both dual filter structures, which include two filter element assemblies arranged in parallel and a switching valve for switching the oil circuits of the two filter element assemblies.

[0010] The new accumulator group is connected to the small turbine regulating oil supply pipeline by a first shut-off valve, and the original accumulator group is connected to the main oil channel by a second shut-off valve.

[0011] The new accumulator group is equipped with a first return oil pipeline, and the original accumulator group is equipped with a second return oil pipeline. Both the first and second return oil pipelines are connected to the lubricating oil tank of the small machine, and each return oil pipeline is equipped with a normally closed grease valve.

[0012] The new accumulator group and the original accumulator group are both bladder-type accumulators.

[0013] This also includes an emergency oil pump supply pipeline, one end of which is connected to the small machine lubricating oil tank, and the other end is connected to the downstream pipeline of the lubricating oil filter group on the lubricating oil supply pipeline.

[0014] The main oil channel is provided with a third oil outlet located downstream of the second oil outlet. The third oil outlet is connected to a small machine turning gear oil supply pipeline. The small machine turning gear oil supply pipeline is provided with a small machine turning gear solenoid valve group, and the end of the small machine turning gear oil supply pipeline is connected to a small machine hydraulic turning gear device.

[0015] (III) Beneficial Effects Compared with the prior art, the present invention provides a pressure stabilization and anti-sudden shutdown system for the oil circuit of a small steam turbine quick-closing valve, which has the following beneficial effects: This small steam turbine's quick-closing valve oil circuit pressure stabilization and anti-sudden closure system adds a new accumulator group dedicated to the regulating oil circuit on the oil outlet side of the regulating oil filter. This new accumulator group independently undertakes the pressure stabilization function at the end of the regulating oil circuit, avoiding the problem of the original accumulator, which simultaneously supplies oil to both the lubrication and regulating oil circuits, causing the transient release pressure to be preferentially diverted and consumed by the lubrication oil circuit. At the same time, the new accumulator group is set up close to the regulating oil system, significantly shortening the oil replenishment path and eliminating the response delay and pipeline pressure loss caused by the original accumulator being too far from the quick-closing valve and passing through multiple resistance elements. It can achieve rapid and accurate pressure replenishment during the transient process of regulating oil pressure fluctuations, fundamentally preventing abnormal sudden closure of the quick-closing valve and ensuring the safe and stable operation of the small steam turbine and the unit. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0017] In the diagram: 1. Small machine lubricating oil tank; 2. Oil pump; 3. Main oil passage; 4. Original accumulator group; 5. First oil inlet; 6. Second oil inlet; 7. Lubricating oil supply pipeline; 8. Small machine regulating oil supply pipeline; 9. Small machine turning gear solenoid valve group; 10. Regulating oil filter; 11. New accumulator group; 12. First return oil pipeline; 13. Lubricating oil cooler group; 14. Lubricating oil filter group; 15. Second return oil pipeline; 16. Normally closed slack drain valve; 17. Small machine hydraulic turning gear device; 18. Emergency oil pump supply pipeline; 19. First shut-off valve; 20. Second shut-off valve; 21. Third oil inlet; 22. Small machine turning gear supply pipeline. Detailed Implementation

[0018] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1 The present invention provides a pressure stabilization and anti-sudden shutdown system for the oil circuit of a small steam turbine quick-closing valve, including a small turbine lubricating oil tank 1, an oil pump 2, a main oil passage 3, and a primary accumulator group 4 connected to the main oil passage 3.

[0020] The small turbine lubricating oil tank 1 stores all the lubricating and regulating oil required by the small turbine hydraulic system. Its capacity is designed according to the system's oil consumption and is usually located on the ground or platform foundation near the turbine body. The oil pump 2 is located inside the small turbine lubricating oil tank 1 or at the oil suction port at the bottom of the tank. It is used to transport the pressurized oil in the small turbine lubricating oil tank 1 to the main oil passage 3, providing a continuous and stable pressurized oil source for the entire small turbine oil system. The oil pump 2 can be a screw pump or a gear pump, and its outlet pressure is set according to the requirements of the small turbine regulating oil system and lubricating oil system, typically between 0.8 MPa and 1.2 MPa. The oil outlet of the oil pump 2 is connected to the inlet of the main oil passage 3 via a pipeline.

[0021] Main oil channel 3 is the main oil supply header for the small engine oil system. Its diameter is determined based on the total system flow rate and is typically made of seamless stainless steel. Main oil channel 3 has a first oil inlet 5 and a second oil inlet 6 sequentially along the oil flow direction. The first oil inlet 5 is connected to the lubricating oil supply line 7, and the second oil inlet 6 is connected to the small engine regulating oil supply line 8. This sequential oil intake structure of main oil channel 3 determines the topological relationship where the lubricating oil supply line 7 is located upstream and the small engine regulating oil supply line 8 is located downstream, resulting in an inherent pressure drop along the pipeline. When the system pressure fluctuates, the upstream lubricating oil branch receives compensation oil preferentially, while the downstream regulating oil branch receives compensation significantly later.

[0022] The original accumulator group 4 is connected to the main oil passage 3 and is located upstream of the first oil inlet 5. The original accumulator group 4 is an existing energy storage device in the original small engine oil system. Its inlet is connected to the main oil passage 3, and it is used to release stored pressurized oil into the main oil passage 3 when the system pressure fluctuates, simultaneously stabilizing the pressure of the lubricating oil supply line 7 and the small engine regulating oil supply line 8. The number and volume of the original accumulator group 4 are determined according to the total capacity and load characteristics of the small engine oil system. Typically, two accumulators are connected in parallel to form a group, with a single unit volume of 6.3L to 10L. It should be noted that because the original accumulator group 4 is located upstream of the main oil passage 3 and before the first oil inlet 5, the released pressurized oil must pass through the branching node of the lubricating oil supply line 7 before reaching the downstream regulating oil line. The path is long and contains multiple resistance elements, resulting in an inherent delay in responding to transient fluctuations in the regulating oil pressure of the end-of-line quick-closing valve.

[0023] The inlet end of the small turbine regulating oil supply pipeline 8 is connected to the second oil inlet 6 of the main oil channel 3, and the outlet end is used to connect to the small turbine regulating oil system. The small turbine regulating oil system includes control components such as a quick-closing valve and a quick-closing valve solenoid valve assembly, used to control the opening and closing of the quick-closing valve. A regulating oil filter 10 is installed along the oil flow direction on the small turbine regulating oil supply pipeline 8. The regulating oil filter 10 is used to filter solid particulate impurities in the regulating oil to ensure that the cleanliness of the regulating oil entering the quick-closing valve and the quick-closing valve solenoid valve assembly meets the requirements, preventing the quick-closing valve from jamming or the solenoid valve assembly from failing due to oil contamination. The filtration accuracy of the regulating oil filter 10 is usually 10μm to 20μm, and its inlet and outlet pressure difference should be controlled within 0.1MPa. When the pressure difference exceeds the set value, the filter element needs to be switched or the filter screen replaced.

[0024] A new accumulator group 11 is connected to the oil outlet side of the regulating oil filter 10. The oil outlet of the new accumulator group 11 is only connected to the section of the small engine regulating oil supply pipeline 8 located between the oil outlet side of the regulating oil filter 10 and the small engine regulating oil system, so as to independently supply oil to the small engine regulating oil system. It should be noted that the oil outlet of the new accumulator group 11 is only connected to this section of the regulating oil supply pipeline 8. It is an independent energy storage device dedicated to the end of the regulating oil circuit. The pressure oil stored in it is only released when the pressure in the regulating oil supply pipeline 8 drops, and all of it is released into the regulating oil supply pipeline 8. It will not be diverted and consumed by the lubricating oil supply pipeline 7, ensuring that the end of the regulating oil circuit receives sufficient and timely compensation oil during pressure fluctuation transients.

[0025] The new accumulator group 11 is installed on the oil outlet side of the regulating oil filter 10, adjacent to the small turbine regulating oil system (i.e., the quick-closing valve and the quick-closing valve solenoid valve assembly). The pipeline distance between its oil supply port and the oil inlet of the quick-closing valve should be minimized, usually controlled within 2m. No other resistance elements should be installed in the pipeline except for the quick-closing valve solenoid valve assembly to ensure minimal pressure loss and the fastest response. When the pressure in the regulating oil supply pipeline 8 fluctuates instantaneously due to conditions such as oil pump 2 switching or quick-closing valve operation testing, the new accumulator group 11 can instantly release the stored pressurized oil to the small turbine regulating oil system via the shortest path and with minimal pressure loss to replenish pressure. This fundamentally solves the response delay and pipeline pressure loss problems caused by the original accumulator group 4 being too far from the quick-closing valve and having multiple resistance elements in between.

[0026] The bladder inflation pressure of the new accumulator group 11 should be set according to the normal operating pressure of the regulating oil supply line 8 of the small turbine, typically set to 60% to 80% of the normal operating pressure of the regulating oil. For example, when the normal operating pressure of the regulating oil is 0.8 MPa, the bladder inflation pressure of the new accumulator group 11 can be set to 0.5 MPa. This setting ensures that the new accumulator group 11 stores a certain amount of pressurized oil when the system is operating normally, and can quickly release the stored oil to replenish pressure when the regulating oil pressure drops.

[0027] In this embodiment, the original accumulator group 4 is located on the main oil channel 3 and upstream of the first oil intake port 5. It should be noted that the original accumulator group 4 is located before the oil intake node of the main oil channel 3. The pressure oil released by it needs to pass through the node where the first oil intake port 5 is located. This node is connected to the lubricating oil supply pipeline 7, which causes a portion of the pressure oil released by the original accumulator group 4 to be diverted by the lubricating oil supply pipeline 7. The actual amount of pressure oil reaching the downstream regulating oil supply pipeline 8 is reduced, further exacerbating the problem of insufficient compensation at the end of the regulating oil circuit.

[0028] In this embodiment, the lubricating oil supply pipeline 7 is sequentially equipped with a lubricating oil cooler assembly 13 and a lubricating oil filter assembly 14 along the oil flow direction. The oil outlet of the lubricating oil filter assembly 14 is connected to each lubricating oil terminal through pipelines. The lubricating oil cooler assembly 13 is used to cool the lubricating oil, control the lubricating oil temperature within a suitable operating range, and ensure the viscosity and lubrication effect of the lubricating oil. The lubricating oil cooler assembly 13 can be a tubular oil cooler or a plate heat exchanger, and the cooling medium is usually the unit's open cooling water. The lubricating oil filter assembly 14 is used to filter impurities in the lubricating oil, ensuring that the cleanliness of the lubricating oil entering each lubricating oil terminal meets the requirements, and preventing serious equipment accidents such as bearing wear or bearing burnout caused by poor oil quality. The lubricating oil terminals include, but are not limited to, the following: small turbine thrust bearing, small turbine front bearing, small turbine rear bearing, steam-driven feedwater pump (or steam-driven induced draft fan) front bearing, steam-driven feedwater pump (or steam-driven induced draft fan) rear bearing, and small turbine top shaft oil system, etc.

[0029] In this embodiment, both the regulating oil filter 10 and the lubricating oil filter assembly 14 are dual-filter structures, comprising two parallel filter element assemblies and a switching valve for switching the oil circuits of the two filter element assemblies. It should be noted that the dual-filter structure allows for online switching of the filter element working circuits without interrupting the oil supply, enabling filter element cleaning or replacement, thereby ensuring continuous system operation and avoiding unplanned downtime due to filter element maintenance. The switching valve typically employs a ball valve or slide valve structure, operated manually or electrically to switch the oil circuit from one filter element to the other. The filter element assemblies are made of glass fiber or metal mesh, and the filtration accuracy is determined according to system requirements; the regulating oil filter 10 has a filtration accuracy of 10μm, and the lubricating oil filter assembly 14 has a filtration accuracy of 20μm.

[0030] In this embodiment, a first shut-off valve 19 is installed on the connecting pipeline between the new accumulator group 11 and the small turbine regulating oil supply pipeline 8, and a second shut-off valve 20 is installed on the connecting pipeline between the original accumulator group 4 and the main oil passage 3. It should be noted that the first shut-off valve 19 controls the connection between the new accumulator group 11 and the small turbine regulating oil supply pipeline 8. During normal system operation, this shut-off valve is in the open position, keeping the new accumulator group 11 connected to the regulating oil supply pipeline 8, ensuring that the new accumulator group 11 can replenish pressure to the regulating oil system at any time. The second shut-off valve 20 controls the connection between the original accumulator group 4 and the main oil passage 3. During normal system operation, it is also in the open position, keeping the original accumulator group 4 connected to the main oil passage 3. The two sets of shut-off valves allow each accumulator group to be independently isolated as needed, facilitating the disconnection of the corresponding accumulator group during maintenance without affecting the overall system operation. The shut-off valve can be a ball valve or a gate valve, and its nominal diameter is determined according to the pipe diameter of the accumulator group connection pipeline, usually DN20 to DN40. Since the new accumulator group 11 and the original accumulator group 4 both adopt a single-port connection structure (i.e., the oil inlet and outlet share the same oil port), the first shut-off valve 19 and the second shut-off valve 20 are fully open during normal operation to ensure that the oil can flow freely in both directions. That is, when the system pressure rises, the oil fills the accumulator through this pipeline to store energy, and when the system pressure drops, the pressurized oil stored in the accumulator flows back to the system through the same pipeline to replenish the pressure. During maintenance, the shut-off valve is fully closed to reliably isolate the accumulator group from the system.

[0031] In this embodiment, the new accumulator group 11 is equipped with a first return oil line 12, and the original accumulator group 4 is equipped with a second return oil line 15. Both the first return oil line 12 and the second return oil line 15 are connected to the small machine lubricating oil tank 1, and each return oil line is equipped with a normally closed drain valve 16. It should be noted that the first return oil line 12 is used for safe oil draining when the new accumulator group 11 is under maintenance or malfunction, and the second return oil line 15 is used for safe oil draining when the original accumulator group 4 is under maintenance or malfunction. The two accumulator groups are equipped with independent return oil lines to avoid mutual interference during oil draining. The normally closed drain valve 16 is kept closed during normal system operation and is only manually opened by the operator when pressure relief or accumulator maintenance is required, allowing the oil inside the accumulator group to be discharged to the small machine lubricating oil tank 1 through the return oil line. The normally closed drain valve 16 ensures that the accumulator group will not be depressurized due to accidental opening of the drain valve during normal pressure stabilization operation, ensuring the safety and reliability of system operation. The diameter of the return oil pipeline is determined based on the accumulator group volume and the oil discharge rate, and is usually DN15 to DN25. The end of each return oil pipeline should extend below the oil level in the small machine's lubricating oil tank 1 to prevent air bubbles or splashing during oil return.

[0032] In this embodiment, both the new accumulator group 11 and the original accumulator group 4 are bladder-type accumulators. It should be noted that the bladder-type accumulator utilizes nitrogen gas to isolate the oil, converting the hydraulic energy of the pressurized oil into potential energy through compressed gas storage, and rapidly releasing the stored oil to replenish pressure when the system pressure drops. Bladder-type accumulators have advantages such as oil-gas isolation, oil oxidation resistance, compact structure, light weight, sensitive dynamic response, no easily damaged parts, long service life, and maintenance-free operation, making them particularly suitable for hydraulic pressure stabilization applications requiring rapid response. The bladder-type accumulator mainly consists of a shell, a bladder, a charging valve, and an oil port. The bladder material is nitrile rubber or polyurethane, and the charging medium is high-purity nitrogen gas. The new accumulator group 11 can be configured with appropriate volume and charging pressure according to the compensation requirements at the end of the regulating oil circuit, while the original accumulator group 4 is configured with different parameters according to the wide-area buffering requirements of the main oil passage 3. Both can be independently optimized according to their respective functional positioning.

[0033] This embodiment also includes an emergency oil pump supply pipeline 18. One end of the emergency oil pump supply pipeline 18 is connected to the small machine lubricating oil tank 1, and the other end is connected to the downstream pipeline of the lubricating oil filter group 14 on the lubricating oil supply pipeline 7. It should be noted that the emergency oil pump supply pipeline 18 is used to draw pressurized oil from the small machine lubricating oil tank 1 in emergency situations such as oil pump 2 failure or power failure, and deliver it through the emergency oil pump supply pipeline 18 to the downstream pipeline of the lubricating oil filter group 14 on the lubricating oil supply pipeline 7, and then deliver it to each lubrication terminal, ensuring that the bearings can still obtain sufficient lubricating oil during the emergency shutdown coasting process of the small machine, and preventing bearing burnout due to oil interruption. The emergency oil pump, as a backup oil source, is usually a gear pump driven by a DC motor and powered by the unit's DC battery to ensure normal operation under the condition of power failure of the entire plant. Its start signal is usually triggered by low outlet pressure of oil pump 2 connected to the main oil passage 3 or low pressure of lubricating oil supply pipeline 7, realizing automatic activation. A check valve can be installed on the oil supply line 18 of the emergency oil pump to prevent pressurized oil from flowing back to the emergency oil pump side during normal operation.

[0034] In this embodiment, a third oil inlet 21 is provided on the main oil passage 3 downstream of the second oil inlet 6. The third oil inlet 21 is connected to the small machine turning gear oil supply pipeline 22. The small machine turning gear oil supply pipeline 22 is equipped with a small machine turning gear solenoid valve group 9, and the end of the small machine turning gear oil supply pipeline 22 is connected to the small machine hydraulic turning gear device 17. It should be noted that the third oil inlet 21 draws oil from the main oil passage 3 and delivers it to the small machine hydraulic turning gear device 17 via the small machine turning gear oil supply pipeline 22. The small machine turning gear solenoid valve group 9 is used to control the opening and closing and direction of the turning gear oil circuit. It is opened before the unit starts or when turning is required after shutdown, so that pressurized oil enters the hydraulic turning gear device to drive the small machine rotor to rotate at low speed to prevent the rotor from bending and deforming due to its own weight. When the unit is running normally, the solenoid valve group is in the closed state, and the turning gear oil supply pipeline 22 does not participate in the system operation.

[0035] In this embodiment, after the new accumulator group 11 is installed, a pressure test and a quick-closing valve switching activity test should be conducted according to the actual operating conditions of the small turbine regulating oil system to ensure that the accumulator bladder pressure is qualified and can achieve the required instantaneous pressure replenishment function. Simultaneously, it should be verified that the newly installed accumulator group 11 has no adverse effect on the normal switching action of the small turbine quick-closing valve. The pressure test can be conducted by using an inflation tool to measure the nitrogen pressure inside the bladder. Operation can only commence after confirming that the pressure is consistent with the set value. The quick-closing valve switching activity test should be conducted with the small turbine stationary. The quick-closing valve is opened and closed by operating the quick-closing valve solenoid valve group. The regulating oil pressure change curve is observed and recorded to confirm that the new accumulator group 11 can quickly respond to pressure fluctuations caused by the quick-closing valve's action and maintain stable regulating oil pressure.

[0036] This invention, by adding a new accumulator group 11 downstream of the regulating oil filter 10, changes the traditional oil supply mode where only a single accumulator is installed on the main oil passage 3 to simultaneously supply both the lubricating oil supply line 7 and the small engine regulating oil supply line 8. This achieves graded independent pressure stabilization of the lubricating oil circuit and the regulating oil circuit. The new accumulator group 11 is dedicated to the end of the regulating oil circuit and is located adjacent to the small engine regulating oil system. Its outlet is only connected to the section of the regulating oil supply line 8 located between the outlet side of the regulating oil filter 10 and the regulating oil system. It can independently and instantaneously replenish oil to the quick-closing valve during pressure fluctuations, avoiding the problem of the original accumulator group 4, which was located upstream of the main oil passage 3 and needed to supply oil to both lines simultaneously, resulting in the pressure release being preferentially consumed by the lubricating oil supply line 7 and the regulating oil circuit compensation being delayed. The original accumulator group 4 is responsible for the wide-area buffering of the main oil passage 3, while the new accumulator group 11 is responsible for the precise compensation at the end of the regulating oil passage. The two work together to fundamentally prevent the abnormal sudden closing of the fast-closing valve and effectively ensure the safe and stable operation of the small steam turbine and the unit.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pressure stabilizing and anti-sudden shut-off system for a small steam turbine's fast-closing valve oil circuit, comprising a small turbine lubricating oil tank (1), an oil pump (2), a main oil passage (3), and a primary accumulator group (4) connected to the main oil passage (3); characterized in that: The main oil channel (3) is provided with a first oil inlet (5) and a second oil inlet (6) in sequence along the oil flow direction. The first oil inlet (5) is connected to a lubricating oil supply pipeline (7), and the second oil inlet (6) is connected to a small engine regulating oil supply pipeline (8). The outlet end of the small machine regulating oil supply pipeline (8) is used to connect to the small machine regulating oil system, and the small machine regulating oil supply pipeline (8) is equipped with a regulating oil filter (10). The oil outlet side of the regulating oil filter (10) is connected to a new accumulator group (11). The oil outlet of the new accumulator group (11) is only connected to the section of the small engine regulating oil supply pipeline (8) located between the oil outlet side of the regulating oil filter (10) and the small engine regulating oil system, so as to independently supply oil to the small engine regulating oil system.

2. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine fast-closing valve according to claim 1, characterized in that, The original accumulator group (4) is installed on the main oil channel (3) and is located in the upstream area of ​​the first oil intake (5).

3. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine quick-closing valve according to claim 1, characterized in that, The lubricating oil supply pipeline (7) is provided with a lubricating oil cooler group (13) and a lubricating oil filter group (14) in sequence along the oil flow direction. The oil outlet of the lubricating oil filter group (14) is connected to each lubricating oil terminal through the pipeline.

4. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine quick-closing valve according to claim 3, characterized in that, The regulating oil filter (10) and the lubricating oil filter group (14) are both dual filter structures, which include two filter element assemblies arranged in parallel and a switching valve for switching the oil circuit of the two filter element assemblies.

5. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine quick-closing valve according to claim 1, characterized in that, A first shut-off valve (19) is provided on the connecting pipeline between the new accumulator group (11) and the small machine regulating oil supply pipeline (8), and a second shut-off valve (20) is provided on the connecting pipeline between the original accumulator group (4) and the main oil channel (3).

6. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine fast-closing valve according to claim 1, characterized in that, The new accumulator group (11) is provided with a first oil return line (12), and the original accumulator group (4) is provided with a second oil return line (15). The first oil return line (12) and the second oil return line (15) are both connected to the small machine lubricating oil tank (1), and each oil return line is provided with a normally closed oil drain valve (16).

7. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine quick-closing valve according to claim 1, characterized in that, The new accumulator group (11) and the original accumulator group (4) are both bladder-type accumulators.

8. The oil circuit pressure stabilization and anti-sudden shutdown system for a small steam turbine fast-closing valve according to claim 1, characterized in that, It also includes an emergency oil pump supply line (18), one end of which is connected to the small machine lubricating oil tank (1), and the other end is connected to the downstream pipeline of the lubricating oil filter group (14) on the lubricating oil supply line (7).

9. A pressure-stabilizing and anti-sudden-shutdown system for a small steam turbine fast-closing valve oil circuit according to claim 1, characterized in that, A third oil outlet (21) is provided on the main oil channel (3) downstream of the second oil outlet (6). The third oil outlet (21) is connected to a small machine turning wheel oil supply pipeline (22). The small machine turning wheel oil supply pipeline (22) is equipped with a small machine turning wheel solenoid valve group (9), and the end of the small machine turning wheel oil supply pipeline (22) is connected to a small machine hydraulic turning wheel device (17).

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