A method for purging a governing system in a steam turbine

Abstract

The application discloses a flushing method for a speed regulating system in a steam turbine, and belongs to the field of steam turbine flushing. The method comprises the following steps: firstly, heating original fire-resistant oil to carry out oil circulation and flushing, and then discharging the oil; replacing servo valves, electromagnetic valves, shut-off valves and emergency stop valves in the speed regulating system with flushing plates, removing throttling holes, injecting flushing oil, and adopting a large-flow circulation flushing method to carry out twice flushing; restoring part of the valves and the throttling holes, and then flushing oil cylinders of oil motors in the speed regulating system; during the flushing process, continuously filtering the fire-resistant oil, discharging waste oil after the oil quality reaches a standard; adding working oil, carrying out oil circulation of the speed regulating system, and restoring the servo valves after the oil quality reaches the standard. The method adopts the large-flow circulation flushing method, can accelerate the flow speed of the oil in the system, enhances the flushing effect, ensures the comprehensiveness and thoroughness of the flushing through multiple times of flushing, and improves the flushing efficiency.

Description

Technical Field

[0001] This invention relates to the field of steam turbine flushing technology, and more particularly to a flushing method for the speed control system in a steam turbine. Background Technology

[0002] The turbine speed control system is a core subsystem ensuring the efficient and safe operation of the turbine. Its primary task is to provide high-quality phosphate ester fire-resistant oil to the turbine's regulating and protection systems. This oil not only handles energy transfer but also performs multiple functions, including lubrication, cooling, sealing, and rust prevention, making it crucial for maintaining the overall performance of the turbine. The speed control system precisely supplies oil to the shut-off valves and regulating valve operating mechanisms of the high-pressure and low-pressure cylinders, ensuring that these critical components can respond quickly and accurately to control commands.

[0003] However, as the unit operates for longer periods, phosphate ester fire-resistant oil gradually ages and decomposes under complex environmental conditions, forming deposits inside the oil actuator. These deposits obstruct oil flow, affecting the normal operation of control components such as cartridge valves, and consequently threatening the safe and stable operation of the turbine. Therefore, it is essential to regularly and rigorously flush the inside of the oil actuator to ensure that the equipment functions as intended.

[0004] Currently, the common flushing method for speed control systems involves flushing the system once with a small amount of flushing oil using an oil pump. However, this method has several drawbacks. For example, without disassembling the solenoid valves, shut-off valves, and servo valves, contaminants can easily clog them during flushing, causing servo valve jamming and potentially leading to hydraulic actuator malfunction. Furthermore, without operating the hydraulic actuator, the internal cylinder of the actuator cannot be flushed. Failure to replace the speed control system filter can cause secondary contamination. Incomplete flushing without flushing the accumulator can also lead to incomplete system flushing. Failure to clean the main oil tank can also cause secondary contamination. Finally, a single flush is insufficient to achieve the desired flushing effect and efficiency. Therefore, a more efficient and thorough flushing method for speed control systems is urgently needed to regularly perform rigorous flushing operations and maintain the system in good working condition. Summary of the Invention

[0005] To address the problem of low flushing efficiency in existing steam turbine speed control systems, this invention provides a flushing method for the speed control system in a steam turbine. This invention thoroughly removes aged components and deposits from the oil, restoring unobstructed oil passages, thereby ensuring the quality and performance of phosphate ester fire-resistant oil and providing strong support for the long-term, efficient operation of the steam turbine.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a flushing method for a speed regulating system in a steam turbine, comprising the following steps:

[0008] The original fire-resistant oil in the speed control system is heated to circulate and flush the oil in the speed control system. After flushing, the original fire-resistant oil is discharged.

[0009] Replace the servo valve, solenoid valve, shut-off valve and emergency shut-off valve in the speed control system with flushing plates, remove the throttle orifice, inject fire-resistant oil, and use a high-flow circulation flushing method to flush the speed control system for the first time. After flushing, discharge the fire-resistant oil.

[0010] Inject fire-resistant oil and use a high-flow-rate circulating flushing method to flush the speed control system a second time. When the oil quality reaches the standard, restore the solenoid valve, shut-off valve, emergency shut-off valve and throttle orifice in the speed control system, and then flush the oil cylinder of the hydraulic motor in the speed control system. During the flushing process, continuously filter the fire-resistant oil. After the oil quality reaches the standard, discharge the fire-resistant oil.

[0011] Add working oil, and the speed control system circulates the oil. Once the oil quality reaches the standard, restore the servo valve.

[0012] The oil quality meets the standard that the fire-resistant oil particle size meets SAE AS4059F 5 level.

[0013] The high-flow-rate circulating flushing method is specifically as follows:

[0014] Close all accumulator inlet valves and drain valves of the speed control system;

[0015] Close the front manual door, rear manual door, and bypass door of all hydraulic actuator oil supply filters;

[0016] Start EH oil pump A, adjust the outlet pressure of EH oil pump A to 6MPa, then stop EH oil pump A; start EH oil pump B, and adjust the outlet pressure of EH oil pump B to 6MPa.

[0017] Open the front and rear manual doors of the central valve throttle oil supply filter;

[0018] Open the EH oil B pump filter outlet shut-off valve. When it is halfway open, check the system for leaks. If there is a leak, close the EH oil B pump filter outlet shut-off valve and stop the pump. If there is no leak, fully open the EH oil B pump filter outlet shut-off valve. Then start the EH oil A pump and open the EH oil A pump filter outlet shut-off valve. The EH oil A pump and EH oil B pump will run simultaneously.

[0019] After flushing the Zhonglianmen hydrator for 2-3 hours, open the bypass door of the Zhonglianmen hydrator oil supply filter and continue flushing for 2-3 hours.

[0020] After flushing the central valve oil motor, close the front manual door, rear manual door, and bypass door of the central valve oil motor oil supply filter, and open the front manual door and rear manual door of the main steam valve oil motor oil supply filter. After flushing the main steam valve oil motor for 2-3 hours, open the bypass door of the main steam valve oil motor oil supply filter and continue flushing for 2-3 hours.

[0021] After flushing the main steam valve oil motor, flush the high-pressure valve oil motor and the small oil motor following the same steps as flushing the main steam valve oil motor.

[0022] After all the oil motors have been flushed, open all the accumulator inlet and drain valves to flush each accumulator one by one. At the same time, start the EH oil circulation pump to flush the oil cooler. The flushing time shall not be less than 30 minutes.

[0023] Release the fire-resistant oil, clean the inner wall of the fuel tank and the return oil filter element, and replace the inlet filter elements of the EH oil A pump, EH oil B pump and EH oil circulation pump.

[0024] During the high-flow circulation flushing process, the oil temperature is monitored in real time. When the oil temperature exceeds 65°C, the running oil pump is shut down, and the circulation flushing is resumed when the oil temperature drops below 65°C.

[0025] The flushing of the hydraulic cylinders in the speed control system specifically involves:

[0026] Switch the flushing plate corresponding to the servo valve to the neutral position, start the EH oil A pump, and adjust the outlet pressure of the EH oil A pump to 13.8-14.2 MPa;

[0027] Operate the flushing plate handle corresponding to the servo valve of the hydraulic motor to clean the cylinders of all hydraulic motors in the speed control system in sequence. Each hydraulic motor is flushed twice, and each flushing lasts for 8-9 hours. After the hydraulic motor is flushed, place the flushing plate handle in the middle position and circulate to flush the cylinders of each hydraulic motor until the oil quality is qualified.

[0028] During the flushing process, continuously filter fire-resistant oil and check for leaks. Take samples for testing daily. Continue flushing until the oil quality meets SAE AS 4059F 5 standards.

[0029] During the flushing process of the hydraulic cylinder of the speed control system, the oil temperature is controlled below 65℃. When the oil temperature exceeds 65℃, the cooling water system is activated. If the oil temperature still exceeds 65℃, the running oil pump is shut down, and the circulation flushing is carried out again when the oil temperature is below 65℃.

[0030] The process of adding working oil and circulating it in the speed control system until the oil quality meets the standard requirements is completed, then restoring the servo valve, specifically:

[0031] Add working oil to the specified level in the oil tank, turn on the oil filter to circulate the oil in the tank, and ensure that the fire-resistant oil particle size index reaches SAE AS4059F level 5. Then, the speed control system starts oil circulation. During the oil circulation process, the working oil is continuously filtered. Samples are taken and tested once a day. Once the oil quality reaches SAE AS4059F level 5, circulation is stopped and the servo valve is reinstalled.

[0032] Replace all filters in the speed control system before adding working oil.

[0033] During the addition of working oil and the oil circulation process of the speed regulating system, the pressure of the main pipe of the speed regulating system is between 14±0.2MPa, the oil level in the oil tank is between 350mm and 400mm, the oil temperature in the oil tank is between 35 and 54℃, and the differential pressure of the outlet filters of all oil pumps is less than 0.5MPa.

[0034] During the above flushing process, if the differential pressure across the oil filter exceeds 0.35 MPa, replace the filter element.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This method employs a high-flow-rate circulating flushing approach, which accelerates the flow rate of oil within the system, enhancing the flushing effect and allowing sludge to be carried out of the system more quickly. Multiple flushing processes, including an initial flush, a first high-flow-rate flush, a second high-flow-rate flush, and flushing of the hydraulic actuator cylinders, ensure comprehensive and thorough flushing, improving flushing efficiency. During the flushing process, servo valves, solenoid valves, shut-off valves, and emergency shut-off valves are replaced with flushing plates, and throttle orifices are removed to ensure the high-flow-rate flushing is carried out effectively and to prevent potential damage to these precision components. Simultaneously, the main fuel tank is cleaned during the flushing process to ensure that the tank does not contaminate the newly injected fuel after flushing. Throughout the flushing process, the fuel is continuously filtered to ensure the fuel quality meets standards and to facilitate the removal of dissolved sludge from the system. Only after the fuel quality meets standards are further operations performed, such as restoring solenoid valves and shut-off valves, effectively preventing the introduction of new contamination sources due to substandard fuel quality and reducing the risk of system contamination. Thorough rinsing and filtration ensure the quality of the oil in the speed control system, providing a strong guarantee for the stable operation of the system.

[0037] Furthermore, by adopting a high-flow-rate circulating flushing method, the oil flow can be concentrated to clean all hydraulic actuators sequentially, ensuring a comprehensive cleaning of the speed control system and reducing cleaning dead spots.

[0038] Furthermore, the oil temperature must be kept below 65°C during the rinsing process. By controlling the oil temperature, the oil quality is prevented from deteriorating too quickly at high temperatures, thus reducing the impact on the speed control system. Rinsing at a suitable oil temperature helps to better flush out impurities and contaminants in the oil, improving the rinsing effect. Moreover, a suitable temperature ensures operational safety.

[0039] Furthermore, after two flushes, working oil is added for oil circulation. During the circulation process, various indicators are monitored and checked to ensure that the speed control system meets the operating standards. Then, the servo valve is reinstalled to avoid damage to precision components such as the servo valve due to substandard oil quality. This helps to reduce operating costs and save resources.

[0040] Furthermore, when the differential pressure across the oil filter exceeds 0.35 MPa, replacing the filter element can improve filtration efficiency and ensure the quality of fire-resistant oil. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0042] Figure 1 This is a flowchart of the flushing method for the speed control system in the steam turbine of the present invention;

[0043] Figure 2 This is a flowchart of the high-flow-rate circulating flushing method of the present invention. Detailed Implementation

[0044] 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, not all, of the embodiments of the present invention. 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.

[0045] In the description of this invention, it should be understood that 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.

[0046] 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.

[0047] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" relationship.

[0048] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0049] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0050] 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.

[0051] like Figure 1 As shown, the present invention provides a flushing method for a steam turbine speed control system, comprising the following steps:

[0052] Heat the original fire-resistant oil in the speed control system to 60-65℃, circulate and flush the oil in the speed control system, and then discharge the original fire-resistant oil after flushing.

[0053] Replace the servo valve, solenoid valve, shut-off valve and emergency shut-off valve in the speed control system with flushing plates, remove the throttle orifice, inject fire-resistant flushing oil, and use a high-flow circulation flushing method to flush the speed control system for the first time. After flushing, discharge the fire-resistant oil.

[0054] The speed control system is flushed a second time using a high-flow-rate circulating flushing method after the new fire-resistant oil is injected. Once the oil quality meets the standard requirements, the solenoid valves, shut-off valves, emergency shut-off valves, and throttle orifices in the speed control system are restored. Then, the cylinders of the hydraulic actuators in the speed control system are flushed. During the flushing process, the fire-resistant oil is continuously filtered. Once the oil quality meets the standard requirements, the fire-resistant oil is discharged.

[0055] Add working oil, and the speed control system circulates the oil until the oil quality meets the standard requirements, then restore the servo valve.

[0056] like Figure 2 As shown, the high-flow-rate circulating flushing method specifically includes:

[0057] Close all accumulator inlet valves and drain valves of the speed control system;

[0058] Close the front manual door, rear manual door, and bypass door of all hydraulic actuator oil supply filters;

[0059] Adjust the pressure of EH oil pump A and EH oil pump B to the lowest level (i.e., loosen the locking nut in the pressure compensator and adjust the adjusting screw to the maximum length), start EH oil pump A, and slowly adjust the pressure setting of pump A until the outlet pressure of pump A reaches 6MPa, then stop EH oil pump A; start EH oil pump B, and slowly adjust the pressure setting of pump B until the outlet pressure of pump B reaches 6MPa.

[0060] Open the front and rear manual doors of the central valve throttle oil supply filter;

[0061] Open the EH oil B pump filter outlet shut-off valve. When it is halfway open, check the system for leaks. If there is a leak, close the EH oil B pump filter outlet shut-off valve and stop the pump. If there is no leak, fully open the EH oil B pump filter outlet shut-off valve. Then start the EH oil A pump and open the EH oil A pump filter outlet shut-off valve. The EH oil A pump and EH oil B pump will run simultaneously.

[0062] After flushing the Zhonglianmen hydrator for 2-3 hours, open the bypass door of the Zhonglianmen hydrator oil supply filter and continue flushing for another 2-3 hours.

[0063] After flushing the central valve oil motor, close the front manual door, rear manual door, and bypass door of the central valve oil motor oil supply filter, and open the front manual door and rear manual door of the main steam valve oil motor oil supply filter. After flushing the main steam valve oil motor for 2-3 hours, open the bypass door of the main steam valve oil motor oil supply filter and continue flushing for 2-3 hours.

[0064] After flushing the main steam valve oil motor, flush the high-pressure valve oil motor and the A and B small steam valve oil motors following the same steps as flushing the main steam valve oil motor.

[0065] After all the oil motors have been flushed, open all the accumulator inlet and drain valves to flush each accumulator one by one. At the same time, start the EH oil circulation pump to flush the oil cooler. The flushing time shall not be less than 30 minutes.

[0066] Drain the waste oil from the oil tank, clean the inner wall of the oil tank and the return oil filter element, and replace the inlet filter elements of the EH oil A pump, EH oil B pump and EH oil circulation pump.

[0067] Preferably, during the high-flow circulation flushing process, the oil temperature is monitored. When the oil temperature exceeds 65°C, all oil pumps are stopped, and the circulation flushing is resumed after the oil temperature drops.

[0068] Preferably, during the high-flow-rate circulating flushing process, the weld seams and bends of the oil pipe are tapped to help foreign objects inside the pipe fall off, and the speed control system is carefully checked for leaks and dealt with in a timely manner.

[0069] The specific steps for flushing the hydraulic cylinder of the hydraulic actuator in the speed control system include:

[0070] Switch the servo valve flushing plate to the neutral position, start the EH oil A pump, and adjust the EH oil A pump outlet pressure to 13.8-14.2 MPa;

[0071] Clean the cylinders of all hydraulic actuators in sequence. Operate the flushing plate handle corresponding to the hydraulic actuator servo valve (main steam valve No. 1, and the middle main valves No. 1 and No. 2 do not have servo valves, so operate their corresponding solenoid valves). This operation activates the hydraulic actuator (the hydraulic actuator is turned on when the handle is in the lower position and turned off when the handle is in the upper position). Each hydraulic actuator is activated twice. After the hydraulic actuators have finished activating, place the flushing plate handle in the middle position.

[0072] Flushing the oil cylinders of each hydraulic actuator until the oil quality is up to standard, keeping the oil filter running during the flushing process, and checking for any leaks.

[0073] Samples should be taken and tested daily. The oil should be continuously flushed until it reaches SAE AS 4059F Grade 5, at which point the second flushing should be completed.

[0074] Preferably, the oil temperature is strictly controlled within 65°C. If the oil temperature is too high, the cooling water system is activated; if the oil temperature still cannot be lowered, the system is shut down.

[0075] Add working oil, circulate the oil in the speed control system, and once the oil quality meets the standard requirements, reset the servo valve. Specifically:

[0076] Add working oil to the specified level in the oil tank, turn on the oil filter to circulate the oil in the tank, and ensure that the fire-resistant oil particle size index reaches SAE AS4059F level 5. Then, the speed control system starts oil circulation. During the oil circulation process, the oil filter runs continuously to filter the working oil. Take a sample for testing once a day. After the oil quality reaches SAE AS4059F level 5, stop the circulation and reinstall the servo valve.

[0077] Replace all filters in the speed control system before adding working oil.

[0078] During the flushing process, if the pressure difference across the oil filter exceeds 0.35 MPa, the filter element of the oil filter should be replaced.

[0079] During the oil circulation process of the speed control system, the following checks should be performed:

[0080] Check that the main pipe pressure of the speed control system is between 14±0.2MPa, and observe for oil leaks and vibrations in the speed control system pipelines and equipment.

[0081] Check the oil level in the tank to 350mm-400mm. If the oil level is too high, the EH oil pump will stop and cause oil overflow. If the oil level is low, find out the cause and eliminate it in time. If necessary, notify maintenance to add oil.

[0082] Check the current, vibration, sound, bearing temperature, and outlet pressure of EH oil pump A, EH oil pump B, and EH oil circulation pump. The standby pump is in standby mode.

[0083] Check that the differential pressure of all oil pump outlet filters is less than 0.5 MPa and there is no indication of blockage;

[0084] Check the oil temperature in the tank; it should be between 35 and 54°C. If the oil temperature is above 54°C and cannot be adjusted, switch the oil cooler or run it in parallel. Find the cause of the high oil temperature and eliminate it.

[0085] The differential pressure readings from the EH oil to each user's filter screen are normal.

[0086] Example

[0087] Taking the fire-resistant oil system of the turbine of Unit 1 of a certain company as an example, the above-mentioned flushing method was applied for flushing.

[0088] The fire-resistant oil system of Unit 1 turbine includes 2 EH main oil pumps, 2 circulating oil pumps, 2 main steam valves, 4 high-pressure control valves, 2 intermediate control valves, and A and B turbines.

[0089] Preparation before rinsing:

[0090] Inventory all flushing plates and seals of the speed control system to ensure that all flushing spare parts are available.

[0091] Inventory of spare parts for the speed control system, including servo valves, solenoid valves, shut-off valves, and filter elements, to ensure sufficient quantity;

[0092] Prepare spare oil containers for use in discharging the oil, and ensure they are clean;

[0093] Prepare 600L of domestic fire-resistant oil flushing oil, 600L + 1200L of domestic fire-resistant oil new oil, and 600L of domestic fire-resistant oil new oil for emergency treatment;

[0094] Prepare one set of oil filtration machine (with online monitoring function) and matching filter elements.

[0095] The flushing process for the fire-resistant oil system of Unit 1 turbine includes:

[0096] On the first day of Unit 1's shutdown, the original fire-resistant oil was heated to 60°C. The EH oil A pump of the speed control system was then activated to circulate and flush the system oil for at least 5 hours. After flushing, the original fire-resistant oil was discharged into a clean EH oil spare tank, ensuring the recovered oil quality met standards. After draining the oil, the main oil pump, circulating oil pump, accumulator, oil cooler, and other related equipment of the speed control system were inspected. Any defects found were promptly repaired and rectified to ensure the equipment could operate normally.

[0097] On the second day after Unit 1 was shut down, after confirming that all equipment in the speed control system was in normal condition, 600L of domestically produced fire-resistant flushing oil was injected into the oil tank. Simultaneously, the servo valves, solenoid valves, shut-off valves, and emergency shut-off valves in the speed control system were replaced with flushing plates, and throttle orifices (a total of 17 locations, including 6 emergency shut-off modules, 2 main steam valves, 4 high-pressure control valves, 2 intermediate-pressure combined steam valves, and 3 primary and secondary industrial exhaust quick-closing valves) were removed. After the fire-resistant flushing oil injection and flushing plate replacement were completed, the speed control system was flushed for the first time using a high-flow-rate circulating flushing method.

[0098] Close all accumulator inlet valves and drain valves of the speed control system;

[0099] Close the front manual door, rear manual door, and bypass door of all hydraulic actuator oil supply filters;

[0100] Start EH oil pump A, slowly adjust the pressure setting of EH oil pump A until the outlet pressure of EH oil pump A reaches 6MPa, then stop EH oil pump A; start EH oil pump B, slowly adjust the pressure setting of EH oil pump B until the outlet pressure of EH oil pump B reaches 6MPa.

[0101] Open the front and rear manual doors of the oil supply filter screens for the hydraulic actuators of doors 1 and 2;

[0102] Open the EH oil B pump filter outlet shut-off valve. When it is halfway open, check the system for leaks. If there is a leak, close the EH oil B pump filter outlet shut-off valve and stop the pump. If there is no leak, fully open the EH oil B pump filter outlet shut-off valve. Then start the EH oil A pump and open the EH oil A pump filter outlet shut-off valve. The EH oil A pump and EH oil B pump will run simultaneously.

[0103] After flushing the No. 1 and No. 2 central valve oil motors for 2 hours, open the bypass door of the No. 1 and No. 2 central valve oil motor oil supply filter screen and continue flushing for 2 hours.

[0104] After flushing the No. 1 and No. 2 central valve oil motors, close the front manual door, rear manual door, and bypass door of the No. 1 and No. 2 central valve oil motor oil supply filter screens, and at the same time open the front manual door and rear manual door of the No. 1 and No. 2 main steam valve oil motor oil supply filter screens. After flushing the No. 1 and No. 2 main steam valve oil motors for 2 hours, open the bypass door of the No. 1 and No. 2 main steam valve oil motor oil supply filter screens and continue flushing for 2 hours.

[0105] After flushing the No. 1 and No. 2 main steam valve oil motors, flush the No. 1, No. 2, No. 3, No. 4 high-adjustment valve oil motors and the A and B small-adjustment valve oil motors according to the flushing steps of the main steam valve oil motors.

[0106] After all the oil motors have been flushed, open all the accumulator inlet and drain doors to flush each accumulator one by one. At the same time, start the circulating oil pump to flush the oil cooler. The flushing time is 30 minutes.

[0107] Drain the waste oil from the oil tank, clean the inner wall of the oil tank and the return oil filter element, and replace the inlet filter elements of the EH oil A pump, EH oil B pump and circulating oil pump.

[0108] 600L of domestically produced new fire-resistant oil is injected into the oil tank. A second flush is performed using a high-flow circulation flushing method. After flushing, the oil quality is sampled and tested. Once the air release value, foam characteristics, kinematic viscosity, and flash point meet the requirements of the operating oil standard, the oil filter is turned on and filtered until the fire-resistant oil particle size meets SAE AS4059F Grade 5. All oil cylinders of the oil actuator are then prepared for flushing.

[0109] After the particle size of the second flushing oil meets SAE AS4059F level 5, the main oil pump is stopped. The solenoid valves, shut-off valves, emergency shut-off valves, and throttle orifices of the main steam valve, high-pressure valve, and intermediate valve are reinstalled, and all seals are replaced during reinstallation. The oil actuator is then flushed. During the flushing process, the oil filter continuously filters fire-resistant oil until the particle size of the fire-resistant oil in the entire system meets SAE AS4059F level 5. The system is then stopped and the second flushing oil is drained. The flushing oil is collected, processed, inspected, and archived.

[0110] Replace all filters in the speed control system after the second flush.

[0111] After the speed control system filter element is replaced, inject 1200L of domestically produced new fire-resistant oil to reach the specified oil level in the tank. Then, start the Super Fire-Resistant Oil Filter to circulate the oil in the tank. Ensure that the fire-resistant oil particle size index reaches SAE AS4059F Grade 5 before starting the oil system circulation. During the oil circulation of the speed control system, the filter runs continuously, and samples are taken for testing once a day. After the oil quality test reaches SAE AS4059F Grade 5, stop the circulation and take a full sample of oil for analysis and record.

[0112] After the above rinsing is completed, the servo valve is reinstalled, and the valve movement test of the main unit and the auxiliary unit is carried out.

[0113] During the flushing process of the speed control system, pay attention to keeping the oil temperature below 65℃; if the oil temperature is still higher than 65℃ after adding cooling water, the pump should be stopped, the cause should be identified and dealt with, and then flushing should be carried out.

[0114] After the replacement imported phosphate ester fire-resistant oil is collected, it is centrally filtered. Once the oil quality is qualified, it is used as backup oil for Unit 2. Waste phosphate ester fire-resistant oil must not be discharged arbitrarily. Scrapped and spilled phosphate ester fire-resistant oil should be collected centrally and disposed of in a standardized manner.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A flushing method for a speed regulating system in a steam turbine, characterized in that, Includes the following steps: The original fire-resistant oil in the speed control system is heated to circulate and flush the oil in the speed control system. After flushing, the original fire-resistant oil is discharged. Replace the servo valve, solenoid valve, shut-off valve and emergency shut-off valve in the speed control system with flushing plates, remove the throttle orifice, inject fire-resistant oil, and use a high-flow circulation flushing method to flush the speed control system for the first time. After flushing, discharge the fire-resistant oil. Inject fire-resistant oil and use a high-flow-rate circulating flushing method to flush the speed control system a second time. When the oil quality reaches the standard, restore the solenoid valve, shut-off valve, emergency shut-off valve and throttle orifice in the speed control system, and then flush the oil cylinder of the hydraulic motor in the speed control system. During the flushing process, continuously filter the fire-resistant oil. After the oil quality reaches the standard, discharge the fire-resistant oil. Add working oil, and the speed control system circulates the oil. Once the oil quality reaches the standard, the servo valve is reset. The high-flow-rate circulating flushing method is specifically as follows: Close all accumulator inlet valves and drain valves of the speed control system; Close the front manual door, rear manual door, and bypass door of all hydraulic actuator oil supply filters; Start EH oil pump A, adjust the outlet pressure of EH oil pump A to 6MPa, then stop EH oil pump A; start EH oil pump B, and adjust the outlet pressure of EH oil pump B to 6MPa. Open the front and rear manual doors of the central valve throttle oil supply filter; Open the EH oil B pump filter outlet shut-off valve. When it is halfway open, check the system for leaks. If there is a leak, close the EH oil B pump filter outlet shut-off valve and stop the pump. If there is no leak, fully open the EH oil B pump filter outlet shut-off valve. Then start the EH oil A pump and open the EH oil A pump filter outlet shut-off valve. The EH oil A pump and EH oil B pump will run simultaneously. After flushing the Zhonglianmen hydrator for 2-3 hours, open the bypass door of the Zhonglianmen hydrator oil supply filter and continue flushing for 2-3 hours. After flushing the central valve oil motor, close the front manual door, rear manual door, and bypass door of the central valve oil motor oil supply filter, and open the front manual door and rear manual door of the main steam valve oil motor oil supply filter. After flushing the main steam valve oil motor for 2-3 hours, open the bypass door of the main steam valve oil motor oil supply filter and continue flushing for 2-3 hours. After flushing the main steam valve oil motor, flush the high-pressure valve oil motor and the small oil motor following the same steps as flushing the main steam valve oil motor. After all the oil motors have been flushed, open all the accumulator inlet and drain valves to flush each accumulator one by one. At the same time, start the EH oil circulation pump to flush the oil cooler. The flushing time shall not be less than 30 minutes. Release the fire-resistant oil, clean the inner wall of the fuel tank and the return oil filter element, and replace the inlet filter elements of EH oil A pump, EH oil B pump and EH oil circulation pump; During the high-flow circulation flushing process, the oil temperature is monitored in real time. When the oil temperature exceeds 65°C, the running oil pump is shut down, and the circulation flushing is resumed when the oil temperature drops below 65°C.

2. The flushing method for a speed regulating system in a steam turbine according to claim 1, characterized in that, The oil quality meets the standard that the fire-resistant oil particle size meets SAE AS4059F 5 level.

3. The flushing method for a speed regulating system in a steam turbine according to claim 1, characterized in that, The flushing of the hydraulic cylinders in the speed control system specifically involves: Switch the flushing plate corresponding to the servo valve to the neutral position, start the EH oil A pump, and adjust the outlet pressure of the EH oil A pump to 13.8~14.2MPa; Operate the flushing plate handle corresponding to the servo valve of the hydraulic motor to clean the cylinders of all hydraulic motors in the speed control system in sequence. Each hydraulic motor is flushed twice, and each flushing lasts for 8-9 hours. After the hydraulic motor is flushed, place the flushing plate handle in the middle position and circulate to flush the cylinders of each hydraulic motor until the oil quality is qualified. During the flushing process, continuously filter fire-resistant oil and check for leaks. Take samples for testing daily. Continue flushing until the oil quality meets SAE AS 4059F 5 standards.

4. The flushing method for a speed regulating system in a steam turbine according to claim 3, characterized in that, During the flushing process of the hydraulic cylinder of the speed control system, the oil temperature is controlled below 65℃. When the oil temperature exceeds 65℃, the cooling water system is activated. If the oil temperature still exceeds 65℃, the running oil pump is shut down, and the circulation flushing is carried out again when the oil temperature is below 65℃.

5. The flushing method for a speed regulating system in a steam turbine according to claim 1, characterized in that, The process of adding working oil and circulating it in the speed control system until the oil quality meets the standard requirements is completed, then restoring the servo valve, specifically: Add working oil to the specified level in the oil tank, turn on the oil filter to circulate the oil in the tank, and ensure that the fire-resistant oil particle size index reaches SAE AS4059F level 5. Then, the speed control system starts oil circulation. During the oil circulation process, the working oil is continuously filtered. Samples are taken and tested once a day. Once the oil quality reaches SAE AS4059F level 5, circulation is stopped and the servo valve is reinstalled.

6. A flushing method for a speed regulating system in a steam turbine according to claim 5, characterized in that, Replace all filters in the speed control system before adding working oil.

7. A flushing method for a speed regulating system in a steam turbine according to claim 5, characterized in that, During the addition of working oil and the oil circulation process of the speed regulating system, the pressure of the main pipe of the speed regulating system is between 14±0.2MPa, the oil level in the oil tank is between 350mm and 400mm, the oil temperature in the oil tank is between 35 and 54℃, and the differential pressure of the outlet filters of all oil pumps is less than 0.5MPa.

8. A flushing method for a speed regulating system in a steam turbine according to any one of claims 1-7, characterized in that, During the flushing process, if the differential pressure across the oil filter exceeds 0.35 MPa, replace the filter element.

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