Integrated switch device for a steam turbine main steam valve

Abstract

The utility model discloses an integrated switch device of steam turbine main steam valve belongs to the automation technical field of power station, including oil motor, integrated block, displacement sensor and control system, is equipped with first pressure oil circuit, second pressure oil circuit and oil discharge passage on integrated block. First pressure oil circuit includes the preheating solenoid valve between pressure oil source and oil motor rod cavity, and its oil return port T is closed. Second pressure oil circuit includes quick -acting solenenum and unloading valve that set gradually between pressure oil source and oil motor rodless cavity, and unloading valve A mouth is communicated with rod cavity, and B mouth is communicated with rodless cavity and oil discharge passage respectively, and control system controls the electrification and power failure of preheating solenoid valve according to the valve position signal of displacement sensor detection, and quick -acting solenenum is controlled to realize main steam valve quick -acting. The utility model realizes the preheating function that traditional need servo system can complete with switch control mode, solves the problem of high cost, low utilization of prior art, and has the advantages of high reliability, good economy.

Description

Technical Field

[0001] This utility model relates to the field of power plant automation technology, and in particular to an integrated switching device for the main steam valve of a steam turbine. Background Technology

[0002] The starting methods for steam turbine generator sets are categorized into cold start and hot start based on the metal temperature of the high-pressure inner cylinder inlet chamber before turbine startup. A cold start occurs when the metal temperature of the high-pressure inner cylinder inlet chamber is below 150℃. During a cold start, the main steam valve must be opened to the required preheating degree based on the steam turbine valve shell metal temperature and the temperature difference between the inner and outer walls. The regulating valve remains closed, controlling the steam flow into the main steam valve and regulating valve to ensure uniform heating of the valve metal components. This preheats the main steam regulating valve shell, ensuring the valve shell metal temperature and the temperature difference between the inner and outer walls reach the required levels. This prevents excessive thermal stress on the valves during turbine startup, which could cause deformation or damage. After preheating, the main steam valve is fully opened according to the startup command and remains fully open during unit operation.

[0003] The turbine main steam valve is a two-position switch type valve. When the unit is shut down, the main steam valve is fully closed; during operation, it is fully open, requiring no adjustment of the valve opening. The main steam valve without preheating function is equipped with a two-position switch type hydraulic actuator controlled by a solenoid valve. According to control commands, the solenoid valve is energized to close the main steam valve, and de-energized to open it. This switch type hydraulic actuator can only fully open and fully close the valve; it cannot control and maintain the main steam valve opening within a specific range as required for valve warming. Therefore, the traditional two-position switch type hydraulic actuator does not have a main steam valve preheating function.

[0004] To achieve the preheating function, existing technology uses a continuous hydraulic actuator with electro-hydraulic servo control. A closed-loop valve position control system is formed by the turbine control system, servo valve, and displacement sensor. The servo valve receives commands from the turbine control system to continuously adjust the opening of the main steam valve. The displacement sensor provides feedback on the actual valve position of the main steam valve, causing it to open to the required preheating degree, thus achieving the valve preheating function.

[0005] However, because continuous hydraulic actuators use servo valves, in addition to configuring displacement sensors, the turbine control system requires a dedicated servo card for the servo valves. Servo valves require a working medium cleanliness level of ≤NAS5, while ordinary solenoid valves require a working medium cleanliness level of ≤NAS9. To ensure long-term reliable operation of the servo valves, each continuous hydraulic actuator's inlet pipeline must be equipped with a dedicated oil filter with a differential pressure alarm sensor.

[0006] However, the closed-loop servo control function of the continuous main steam valve hydraulic actuator is only used briefly during the turbine's cold start-up and valve preheating period. After valve preheating is complete, all main steam valves are fully open, and continuous valve position adjustment is no longer required; its function is the same as that of the on / off type hydraulic actuator. Therefore, the servo control function of the continuous main steam valve preheating hydraulic actuator suffers from technical problems such as high equipment cost and low utilization rate. Utility Model Content

[0007] The purpose of this utility model is to solve the above-mentioned problems existing in the prior art and to provide an integrated switching device for the main steam valve of a steam turbine. This effectively solves the technical problems that traditional on / off type hydraulic actuators cannot achieve preheating function, while continuous servo hydraulic actuators suffer from high cost and low utilization rate due to the use of servo valves. This improves the reliability, economy and maintenance convenience of the on / off type hydraulic actuator preheating main steam valve.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An integrated switching device for a steam turbine main steam valve includes a hydraulic actuator, an integrated block, a displacement sensor, and a control system. The integrated block has a first pressure oil circuit, a second pressure oil circuit, and a drain oil passage. The first pressure oil circuit includes a preheating solenoid valve disposed between a pressure oil source and the rod chamber of the hydraulic actuator via a flow channel, with the return port T of the preheating solenoid valve closed. The second pressure oil circuit includes a quick-closing solenoid valve and an unloading valve disposed sequentially between a pressure oil source and the rodless chamber of the hydraulic actuator via a flow channel. Port A of the unloading valve is connected to the rod chamber, and port B is connected to both the rodless chamber and the drain oil passage. The displacement sensor is fixed to the hydraulic actuator to detect the valve position of the main steam valve. The control system is connected to both the quick-closing solenoid valve and the preheating solenoid valve to control the de-energization and energization of the quick-closing solenoid valve, and controls the de-energization and energization of the preheating solenoid valve based on the main steam valve position detected by the displacement sensor.

[0009] The preheating solenoid valve is a two-position three-way valve. The pressure port P of the preheating solenoid valve is connected to the pressure oil source, and the working port A is connected to the rod chamber of the hydraulic actuator.

[0010] The unloading valve is a two-way cartridge valve, and the quick-closing solenoid valve is a two-position three-way valve. The pressure port P of the quick-closing solenoid valve is connected to the pressure oil source, the working port A is connected to the control chamber on the unloading valve, and the return port T is connected to the drain passage.

[0011] The first pressure oil circuit also includes a throttling orifice disposed between the rod chamber of the hydraulic actuator and the preheating solenoid valve via a flow channel, and the A port on the unloading valve is connected to the flow channel between the throttling orifice and the rod chamber of the hydraulic actuator.

[0012] The first pressure oil circuit also includes a movable test solenoid valve disposed between the throttle orifice and the preheating solenoid valve via a flow channel. The movable test solenoid valve is a two-position three-way valve. The pressure port P of the movable test solenoid valve is connected to the working port A of the preheating solenoid valve. The return port T of the movable test solenoid valve is connected to the drain passage. The working port A of the movable test solenoid valve is connected to the rod chamber of the hydraulic actuator. The control system is connected to the movable test solenoid valve and is used to control the de-energization and energization of the movable test solenoid valve.

[0013] The oil pressure source is provided with an oil supply pressure measuring point through the flow channel; the oil discharge pressure measuring point is provided on the flow channel between the rodless chamber of the oil motor and the B port of the unloading valve; the rod chamber pressure measuring point and the rod chamber pressure sensor are sequentially provided on the flow channel between the rod chamber of the oil motor and the throttle orifice, and the control system is connected to the rod chamber pressure sensor.

[0014] The displacement sensor is coaxially mounted with the piston rod of the hydraulic actuator.

[0015] The advantages of using this utility model are: 1. The integrated switching device for the main steam valve of a steam turbine provided by this utility model firstly constructs a closed-loop valve position control system through the coordinated operation of a preheating solenoid valve, a displacement sensor, and a control system, forming an integrated on / off type hydraulic actuator. Specifically, a preheating solenoid valve with its return port blocked is used as a position-holding valve, and combined with real-time feedback from the displacement sensor, the main steam valve opening is dynamically maintained within a preset threshold range simply by controlling the preheating solenoid valve in both de-energized and energized states. This achieves a preheating function that traditional on / off type hydraulic actuators do not possess.

[0016] Secondly, by controlling the de-energization and energization of the quick-closing solenoid valve through the control system, a reliable rapid closing circuit for the main steam valve is established. Specifically, the control system de-energizes the quick-closing solenoid valve, triggering the unloading valve to close, providing the necessary conditions for establishing oil pressure in the rod chamber of the hydraulic actuator; conversely, upon receiving an emergency shutdown signal, the control system energizes the quick-closing solenoid valve, instantly triggering the unloading valve to open, rapidly releasing the pressure oil in the rod chamber of the hydraulic actuator, and causing the main steam valve to close quickly under the action of the return spring, ensuring the safe operation of the unit.

[0017] Third, the use of conventionally structured preheating solenoid valves and quick-closing solenoid valves in coordination with the control system eliminates the need for continuous electro-hydraulic servo actuators equipped with servo valves. The electrical control system no longer requires a dedicated servo card to control the servo valves; it only needs a relay circuit to control the preheating solenoid valves' energization and de-energization. Furthermore, the preheating and quick-closing solenoid valves have a simple structure and require a working medium cleanliness level of ≤NAS 9, matching the cleanliness level generally achievable by turbine hydraulic control systems (typically ≤NAS 6). This results in stronger resistance to contamination, and the hydraulic control system does not require a dedicated oil filter or differential pressure alarm sensor for the preheating solenoid valves, thus simplifying the turbine's electrical and hydraulic control and protection systems. Moreover, the preheating solenoid valves only briefly energize / de-energize during cold starts and main steam valve preheating, remaining in a static, de-energized state after preheating. In contrast, the servo valves and their control systems of continuous-type hydraulic actuators must be in standby mode throughout the entire unit's operation to ensure they are readily available for servo control. Therefore, the preheating solenoid valve in this invention has a much higher reliability and service life than the servo valve, thereby improving the overall operational reliability of this invention.

[0018] Fourth, by adopting an integrated preheating solenoid valve, quick-closing solenoid valve, and unloading valve in a switching hydraulic actuator, the type of integrated switching device for the turbine main steam valve is standardized and completely interchangeable. More importantly, the preheating solenoid valve and quick-closing solenoid valve can be selected from the same model of two-position three-way valve, achieving complete interchangeability of the core solenoid valves and reducing the types of spare parts. These solenoid valves have a simple structure, require less maintenance, and have high utilization; typically, only on-site replacement of seals is needed. In contrast, servo valves must be returned to a specialized manufacturer and maintained and tested using specialized equipment. Therefore, this invention greatly improves the interchangeability and utilization of the hydraulic actuator and simplifies the maintenance process.

[0019] In summary, this utility model, through the coordinated operation of the control system and the first pressure oil circuit, the second pressure oil circuit, and the oil discharge passage on the integrated block, and by controlling the energization and de-energization of the preheating solenoid valve based on the main steam valve position detected by the displacement sensor, maintains the main steam valve opening within a preset threshold range. This effectively solves the technical problems of traditional on / off type hydraulic actuators being unable to achieve preheating function, and continuous servo hydraulic actuators being costly and having low utilization due to the use of servo valves. It enables the use of ordinary on / off solenoid valves to automatically maintain the main steam valve opening within a preset threshold range, completing the valve preheating required for cold start-up, and improving the reliability, economy, and maintenance convenience of the integrated switching device.

[0020] 2. In this utility model, the reliability of the first pressure oil circuit is ensured by connecting the pressure oil port P and the working oil port A of the preheating solenoid valve.

[0021] 3. In this utility model, by adopting a two-way cartridge unloading valve, a two-position three-way quick-closing solenoid valve, and the connection relationship between the pressure oil port P of the quick-closing solenoid valve and the pressure oil source, the working oil port A and the control chamber on the unloading valve, and the return oil port T and the drain oil passage, the response speed and control accuracy of the quick-closing action are improved.

[0022] 4. In this invention, by setting a throttling orifice in the first pressure oil circuit and arranging it between the rod chamber of the hydraulic actuator and the preheating solenoid valve, and simultaneously connecting the A port of the unloading valve to the downstream flow channel of this throttling orifice, precise regulation of the flow rate in the first pressure oil circuit is achieved. This design not only improves the stability and accuracy of valve opening control during the preheating process, but also ensures that, under emergency rapid closing conditions, the pressure oil in the rod chamber of the hydraulic actuator can only enter the rodless chamber and discharge oil through the controlled unloading valve channel, thereby ensuring the reliability and safety of system pressure relief. Furthermore, this throttling orifice also provides the necessary flow control basis for subsequent online slow closing and slow opening tests, and is key to achieving slow valve operation.

[0023] 5. In this utility model, by adding an active test solenoid valve to the first pressure oil circuit, the online active test function is integrated, which improves the reliability of this utility model.

[0024] 6. In this utility model, by setting pressure measuring points on key oil lines in the oil supply, oil discharge, and rod chamber, and installing a rod chamber pressure sensor connected to the control system, real-time, multi-point monitoring of the pressure status is achieved. This not only allows the pressure signal from the rod chamber to be fed back to the control system in real time, enabling precise closed-loop control and safety interlocking, but also provides crucial data for fault diagnosis and health management, greatly improving the automation level, control accuracy, and operational reliability of the main steam valve preheating process adapted to this utility model.

[0025] 7. In this utility model, by setting the displacement sensor and the piston rod coaxially, the accuracy of the main steam valve position detection and the feedback accuracy of the control system are significantly improved. Attached Figure Description

[0026] Figure 1 A schematic diagram of the hydraulic principle of this utility model when the main steam valve is in the position-holding preheating condition; Figure 2 This is a schematic diagram of the physical structure of the present invention; Figure 3 A schematic diagram of the hydraulic principle of this utility model when the main steam valve is in the fully open working condition; Figure 4 A schematic diagram of the hydraulic principle of this utility model when the main steam valve is in the fast-closing condition; Figure 5 This is a schematic diagram of the hydraulic principle of this utility model when the main steam valve is in the slow-closing condition during the active test.

[0027] The following are the labels in the diagram: 1. Hydraulic actuator, 2. Return spring, 3. Displacement sensor, 4. Preheating solenoid valve, 5. Activity test solenoid valve, 6. Throttling orifice, 7. Rod chamber pressure sensor, 8. Quick-closing solenoid valve, 9. Unloading valve, 10. Discharge pressure measuring point, 11. Rod chamber pressure measuring point, 12. Supply pressure measuring point, 13. First pressure oil circuit, 14. Second pressure oil circuit, 15. Discharge passage, 16. Piston rod, 17. Integrated block, 100. Rod chamber, 200. Rodless chamber. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. For ease of description, the description of the relative positional relationships of each component is based on the layout of the accompanying drawings, such as the positional relationships of front, back, top, bottom, left, and right, which are determined according to the layout direction of the accompanying drawings.

[0029] Example 1 As a basic embodiment of this utility model, this embodiment provides an integrated switching device for the main steam valve of a steam turbine, such as... Figure 1 and Figure 2 As shown, it includes a hydraulic actuator 1, an integrated block 17, a displacement sensor 3, and a control system. The integrated block 17 is equipped with a first pressure oil passage 13, a second pressure oil passage 14, and an oil discharge passage 15. The specific connections and fits between the components are as follows: The piston rod 16 of the hydraulic actuator 1 is connected to the main steam valve stem; The first pressure oil circuit 13 includes a preheating solenoid valve 4 disposed between the pressure oil source and the rod chamber 100 of the oil motor 1 via a flow channel, and the return port T of the preheating solenoid valve 4 is closed. The second pressure oil circuit 14 includes a quick-closing solenoid valve 8 and an unloading valve 9, which are sequentially arranged between the pressure oil source and the rodless chamber 200 of the oil motor 1 through a flow channel. The unloading valve 9 is a two-way cartridge valve with a cover plate, used to control the opening and closing of the rod chamber 100 of the hydraulic actuator 1 and the oil discharge passage 15, thereby realizing the opening and rapid closing of the main steam valve. Figure 1 As shown, port A on unloading valve 9 is connected to rod chamber 100, and port B is connected to rodless chamber 200 and oil discharge passage 15 respectively. Specifically, port B is connected to rodless chamber 200 and oil discharge passage 15 respectively via annular return oil chamber on valve sleeve of unloading valve 9. The specific structure of port B of unloading valve is known in the art and will not be described in detail here.

[0030] Displacement sensor 3 is fixed to hydraulic actuator 1 to detect the main steam valve position. Preferably, displacement sensor 3 is fixed to the outer wall of hydraulic actuator 1 and coaxially arranged with piston rod 16 of hydraulic actuator 1. Specifically, displacement sensor 3 obtains the main steam valve position by continuously detecting the displacement of piston rod 16 of hydraulic actuator 1, and feeds back the main steam valve position to the control system, thereby realizing the display and control of the main steam valve opening.

[0031] The control system is connected to the fast-closing solenoid valve 8 and is used to control the de-energization and energization of the fast-closing solenoid valve 8, thereby realizing the opening and rapid closing of the main steam valve. Specifically, such as... Figure 1 As shown, when the control system de-energizes the fast-closing solenoid valve 8, the unloading valve 9 is closed, blocking the oil discharge between the rod chamber 100 of the hydraulic actuator 1 and the oil discharge passage 15. This provides the necessary conditions for establishing and maintaining oil pressure in the rod chamber 100 of the hydraulic actuator 1, thereby enabling the main steam valve to enter the slow opening and position-holding preheating state. When the control system energizes the fast-closing solenoid valve 8, as... Figure 4 As shown, the unloading valve 9 is in the open state, draining the oil between the rod chamber 100 of the hydraulic actuator 1 and the oil drain passage 15. At this time, with Figure 4 Taking the direction shown as an example, the pressure oil in the rod chamber 100 of the hydraulic actuator 1 will be divided into two paths after passing through port A of the unloading valve 9. One path goes to the left through port B and enters the rodless chamber 200 of the hydraulic actuator 1, while the other path flows to the right through port B to the oil discharge. Under the spring force of the return spring 2 on the hydraulic actuator 1, the piston rod 16 extends downward, and the main steam valve enters the fast closing condition.

[0032] The control system is also connected to the preheating solenoid valve 4, and controls the de-energization and energization of the preheating solenoid valve 4 according to the main steam valve position detected by the displacement sensor 3, so that the opening of the main steam valve is maintained within the preset threshold range, that is, it enters the position-holding preheating mode.

[0033] Accordingly, when applied to the actual preheating condition of the main steam valve, the opening of the main steam valve is usually maintained within a preset threshold range of 5%-10%, which can control the steam flow required for preheating and make the metal temperature of the main steam valve shell rise to the required value evenly, thus meeting the preheating requirements of the main steam valve.

[0034] In addition, it should be noted that, except for the unloading valve 9, all other solenoid valves in this utility model are zero-leakage two-position three-way valves, which are sufficient to effectively maintain the pressure of the rod chamber of the hydraulic actuator during the pressure holding time required for preheating.

[0035] Furthermore, such as Figure 1 and Figure 3 As shown, the pressure port P of the preheating solenoid valve 4 is connected to the pressure oil source, and the working port A is connected to the rod chamber 100 of the hydraulic actuator 1.

[0036] Provided that unloading valve 9 is closed via quick-closing solenoid valve 8, see [link / reference] Figure 3 The control system de-energizes the preheating solenoid valve 4, connecting its pressure port P to the working port A. This causes the main steam valve to slowly open via the piston rod 16 of the hydraulic actuator 1. Specifically, in this de-energized state, pressurized oil enters the rod chamber 100 of the hydraulic actuator 1. This oil pressure overcomes the force of the return spring 2 acting on the piston rod 16 and the steam shut-off force within the hydraulic actuator 1, pushing the piston rod 16 upwards and thus slowly opening the main steam valve. Since the specific connection structure of the piston rod 16, the return spring 2, and the hydraulic actuator 1 is known in the art, it will not be described further here.

[0037] Next, see Figure 1 Based on the main steam valve position detected by displacement sensor 3, the control system controls the preheating solenoid valve 4 to discharge oil while energized, and the working oil port A of the preheating solenoid valve 4 is connected to the return oil port T. Since the return oil port T is blocked and the selected preheating solenoid valve 4 has extremely low leakage, the oil inlet and outlet passages of the rod chamber 100 of the hydraulic actuator 1 are cut off, so that the main steam valve is in the position-holding preheating condition, and the main steam valve position will be maintained until the preheating is completed.

[0038] After the warm-up period ends, please continue to see [the relevant information]. Figure 3 The control system then de-energizes the preheating solenoid valve 4, allowing pressurized oil to continue entering the rod chamber 100 of the hydraulic actuator 1, causing the main steam valve to switch from the position-holding preheating state to the fully open state.

[0039] Furthermore, the first pressure oil circuit 13 also includes a throttling orifice 6 disposed between the rod chamber 100 of the hydraulic actuator 1 and the preheating solenoid valve 4 via a flow channel. The throttling orifice 6 is used to adjust the flow channel pressure oil volume in the first pressure oil circuit 13. Simultaneously, port A of the unloading valve 9 is connected to the flow channel between the throttling orifice 6 and the rod chamber 100 of the hydraulic actuator 1. Therefore, in this invention, regardless of whether the unloading valve 9 is open or closed, its port B is always connected to the rodless chamber 200 of the hydraulic actuator 1, the oil discharge passage 15, and the oil discharge outlet of the oil discharge passage 15 through the annular oil return chamber on the valve sleeve of the unloading valve 9.

[0040] Example 2 Based on Example 1, the connection design for controlling the unloading valve 9 with the fast-closing solenoid valve 8 to achieve the fast-closing condition of the main steam valve has been optimized.

[0041] like Figure 4 As shown, the pressure port P of the quick-closing solenoid valve 8 is connected to the pressure oil source, the working port A of the quick-closing solenoid valve 8 is connected to the control chamber on the unloading valve 9, and the return port T of the quick-closing solenoid valve 8 is connected to the drain passage 15.

[0042] When the control system de-energizes the quick-closing solenoid valve 8, its pressure port P connects to the working port A, and pressure oil is introduced through the flow channel on the second pressure oil circuit 14. Because the unloading valve 9 is a two-way cover cartridge valve, the introduced pressure oil will enter the control chamber of the unloading valve 9 through the pressure port P-working port A of the quick-closing solenoid valve 8. The control area of ​​the unloading valve 9's control chamber is designed to be larger than the control area of ​​its port A (usually the former is about 1.5 times the latter). Under this area difference, the hydraulic pressure generated in the control chamber and the spring force inside the unloading valve are sufficient to overcome the oil pressure at port A, driving the unloading valve core to move downward, closing the main oil discharge passage from port A to port B, and causing the unloading valve 9 to enter the closed state. This state provides the necessary conditions for the establishment and maintenance of oil pressure in the rod chamber 100 of the hydraulic actuator 1, thereby supporting the slow opening of the main steam valve and the preheating process of maintaining position.

[0043] When the control system energizes the quick-closing solenoid valve 8, its working port A connects to the return port T, and the oil in the control chamber of the unloading valve 9 is rapidly depressurized. Under the force generated by the oil pressure in the rod chamber 100 of the hydraulic actuator 1 acting on port A of the unloading valve 9, the valve core of the unloading valve 9 moves upward rapidly, opening the main oil discharge passage from port A to port B. At this time, the pressurized oil in the rod chamber 100 of the hydraulic actuator 1 flows through the opened unloading valve 9, and its oil flow path is consistent with that described in Example 1: after flowing through the unloading valve 9, the oil is divided into two paths, one of which enters the rodless chamber 200 of the hydraulic actuator 1 through port B and the oil discharge passage 15, and the other of which flows to the discharge port through port B and the oil discharge passage 15, thereby achieving rapid closure of the main steam valve.

[0044] Example 3 To ensure the reliability of the main steam valve during long-term operation and to prevent valve jamming, this embodiment adds an online activity test function to the present invention based on embodiment 2.

[0045] Continue to refer to Figure 2 and combined Figure 5 It is understood that the first pressure oil circuit 13 also includes a movable test solenoid valve 5 disposed between the throttle orifice 6 and the preheating solenoid valve 4 via a flow channel. The movable test solenoid valve 5 is a two-position three-way valve. The pressure port P of the movable test solenoid valve 5 is connected to the working port A of the preheating solenoid valve 4. The return port T of the movable test solenoid valve 5 is connected to the drain passage 15. The working port A of the movable test solenoid valve 5 is connected to the rod chamber 100 of the hydraulic actuator 1. The control system is connected to the movable test solenoid valve 5 and is used to control the de-energization and energization of the movable test solenoid valve 5.

[0046] During the main steam valve's operational test, the preheating solenoid valve 4 remains de-energized to ensure unobstructed flow in the first pressure oil circuit 13 leading to the rod chamber 100 of the hydraulic actuator 1, and the quick-closing solenoid valve 8 remains de-energized to ensure the unloading valve 9 is closed. Under these conditions: When the control system energizes the solenoid valve 5 for the active test, the working port A of the solenoid valve 5 is connected to its return port T. At this time, the oil in the rod chamber 100 of the hydraulic actuator 1 is slowly discharged through the solenoid valve 5 after being restricted by the throttle orifice 6, and the oil pressure gradually decreases. Under the action of the return spring 2, the main steam valve overcomes the steam buoyancy and slowly closes through the piston rod 16, entering the slow closing condition, thus realizing the slow closing test.

[0047] When the control system de-energizes the active test solenoid valve 5, the working port A of the active test solenoid valve 5 is connected to its pressure port P. At this time, the pressure oil, after passing through the preheating solenoid valve 4, enters the rod chamber 100 of the hydraulic actuator 1 through the throttling effect of the active test solenoid valve 5 and the throttling orifice 6. The oil pressure is slowly built up, and the piston rod 16 drives the main steam valve to enter the slow opening condition, realizing the slow opening test.

[0048] Example 4 This embodiment optimizes the pressure monitoring design of this utility model based on embodiment 3. For details of the optimization, please refer to [link to specific optimization details]. Figure 1 .

[0049] The oil supply pressure measuring point 12 is provided at the pressure oil source through the flow channel; the oil discharge pressure measuring point 10 is provided on the flow channel between the rodless chamber 200 of the oil motor 1 and the B port of the unloading valve 9; the rod chamber pressure measuring point 11 and the rod chamber pressure sensor 7 are sequentially provided on the flow channel between the rod chamber 100 of the oil motor 1 and the throttle orifice 6, and the control system is connected to the rod chamber pressure sensor 7.

[0050] The oil supply pressure measuring point 12, the oil discharge pressure measuring point 10, and the rod chamber pressure measuring point 11 are all equipped with pressure measurement interfaces; these pressure measuring interface interfaces are used for online installation and disassembly of instruments in the integrated switch device and its hydraulic circuit under pressure conditions of this utility model, which facilitates on-site pressure monitoring and maintenance.

[0051] The rod chamber pressure sensor 7 is used to transmit the pressure signal of the rod chamber 100 of the hydraulic motor 1 to the control system for real-time monitoring, data display, historical data storage and fault analysis.

[0052] In summary, this utility model, through the coordinated operation of the hydraulic circuit and electrical control, realizes the functions of preheating, position holding, full opening, rapid closing, and activity testing of the main steam valve. Its working process, based on different starting conditions and control commands, is divided into the following core operating conditions: I. Initial State and Main Steam Valve Opening When the preheating solenoid valve 4, the quick-closing solenoid valve 8, and the active test solenoid valve 5 are all de-energized, the integrated switching device of this utility model connects to the pressure oil source. The oil circuit is divided into two paths: One path enters the control chamber of the unloading valve 9 through the quick-closing solenoid valve 8 (pressure port P - working port A). Under the action of the hydraulic pressure generated by the area difference between the control chamber of the unloading valve 9 and port A, the unloading valve 9 closes, thereby cutting off the main passage between the rod chamber 100 of the hydraulic actuator 1 and the oil discharge passage 15.

[0053] Another path passes through the preheating solenoid valve 4 (pressure port P - working port A) and the activity test solenoid valve 5 (pressure port P - working port A), and then through the throttle orifice 6 into the rod chamber 100 of the hydraulic motor 1.

[0054] The oil actuator 1 has a rod chamber 100 where pressure is established. This oil pressure overcomes the spring force of the return spring 2 and the steam shut-off force, and drives the main steam valve to open via the piston rod 16.

[0055] II. Preheating and position maintenance conditions The preheating and position-maintaining mode is suitable for cold starts.

[0056] Open to preheating position: The main steam valve slowly opens from the closed state. Displacement sensor 3 detects the valve position in real time and feeds it back to the control system.

[0057] Position-holding control closed loop: When the main steam valve opening reaches the preset high threshold (e.g., 10%), the control system immediately energizes the preheating solenoid valve 4. Since the return port T of the preheating solenoid valve 4 is blocked and the valve core leakage is extremely low, the inlet and outlet oil passages of the rod chamber 100 of the hydraulic actuator 1 are completely cut off, and the main steam valve enters the position-holding condition.

[0058] Dynamic Maintenance: Due to inherent internal leakage in the hydraulic actuator 1 and its associated hydraulic control components, the main steam valve opening will slowly decrease under the action of the return spring 2. When the main steam valve opening drops to a preset low threshold (e.g., 5%), the control system de-energizes the preheating solenoid valve 4, and pressurized oil re-enters the rod chamber 100 of the hydraulic actuator 1 for replenishment, causing the main steam valve opening to slowly rise again to 10%. Through the alternating action of the preheating solenoid valve 4 between the "de-energized" and "energized" states, a closed-loop on / off valve position control is formed, dynamically maintaining the main steam valve opening within the preset threshold range (e.g., 5%-10%), thereby controlling the preheating steam flow and achieving safe and uniform heating of the valve body.

[0059] Preheating complete: After preheating is completed, the control system keeps the preheating solenoid valve 4 de-energized, and the pressurized oil continues to enter, opening the main steam valve from the preheating opening position to the 100% fully open position.

[0060] III. Normal Operation and Quick Shutdown Conditions Normal operation: After the preheating is completed or during hot start-up, the main steam valve is opened to the fully open position and maintained, and the preheating solenoid valve 4, the quick-closing solenoid valve 8 and the active test solenoid valve 5 are all restored to the initial de-energized state.

[0061] Emergency Quick-Close: Under any operating condition, when an emergency shutdown signal occurs, the control system can immediately trigger one of two responses: directly releasing the inlet pressure of the integrated switching device, or energizing the quick-close solenoid valve 8. After the quick-close solenoid valve 8 is energized (working oil port A - return oil port T are connected), the pressure oil in the control chamber of the unloading valve 9 is rapidly released. The valve core of the unloading valve 9 opens instantaneously under the pressure of the rod chamber 100 of the hydraulic actuator 1 and the action of the internal spring. At this time, the oil in the rod chamber 100 of the hydraulic actuator 1 is rapidly discharged through the main discharge passage (port A to port B) of the unloading valve 9. After flowing through the unloading valve 9, the oil is divided into two paths: one path enters the rodless chamber 200 of the hydraulic actuator 1 through port B and the annular return oil chamber, and the other path flows to the discharge passage 15 through port B and the annular return oil chamber. As a result, the main steam valve closes rapidly through the piston rod 16 and under the action of the return spring 2.

[0062] IV. Online Activity Test Conditions To ensure the flexibility of the main steam valve, regular online operation tests are required. During the test, the preheating solenoid valve 4 and the quick-closing solenoid valve 8 are kept de-energized to ensure that the main oil circuit entering the rod chamber 100 of the hydraulic actuator 1 is unobstructed and the unloading valve 9 is closed.

[0063] Slow-closing test: When the control activity test solenoid valve 5 is energized (working oil port A-return oil port T are connected), the oil in the rod chamber 100 of the oil motor 1 can only be discharged slowly through the throttle orifice 6 in its oil circuit. As a result, the main steam valve slowly closes under the action of the return spring 2.

[0064] Slow-opening test: When the control activity test solenoid valve 5 is de-energized (pressure oil port P and working oil port A are connected), the pressure oil, after passing through the preheating solenoid valve 4, can only slowly enter the rod chamber 100 of the oil motor 1 through the throttle orifice 6, and the main steam valve opens slowly accordingly.

[0065] Therefore, this utility model combines the preheating solenoid valve 4 of a common switch with the displacement sensor 3 and control logic to construct a cost-controllable and highly reliable valve position range control closed loop. It successfully realizes the preheating function that the prior art requires an expensive servo system to complete in the form of a switch control method, while retaining the complete fast closing and activity testing capabilities. It effectively solves the technical problems of high equipment cost, low utilization rate and complex maintenance in the prior art.

[0066] The above description is only a specific embodiment of the present utility model. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All features or steps in all methods or processes disclosed may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. An integrated switching device for the main steam valve of a steam turbine, characterized in that: The system includes a hydraulic actuator (1), an integrated block (17), a displacement sensor (3), and a control system. The integrated block (17) is provided with a first pressure oil circuit (13), a second pressure oil circuit (14), and an oil discharge passage (15). The first pressure oil circuit (13) includes a preheating solenoid valve (4) which is disposed between the pressure oil source and the rod chamber (100) of the hydraulic actuator (1) through a flow channel. The return port T of the preheating solenoid valve (4) is closed. The second pressure oil circuit (14) includes a quick-closing solenoid valve (8) and an unloading valve (9) which are disposed sequentially between the pressure oil source and the rodless chamber (200) of the hydraulic actuator (1) through a flow channel. Port A of the unloading valve (9) is connected to the rod chamber (100), and port B is connected to the rodless chamber (200) and the oil discharge passage (15) respectively. The displacement sensor (3) is fixed on the hydraulic actuator (1) to detect the position of the main steam valve. The control system is connected to the fast-closing solenoid valve (8) and the preheating solenoid valve (4) respectively, and is used to control the de-energization and energization of the fast-closing solenoid valve (8); and controls the de-energization and energization of the preheating solenoid valve (4) according to the valve position of the main steam valve detected by the displacement sensor (3).

2. The integrated switching device for the main steam valve of a steam turbine according to claim 1, characterized in that: The preheating solenoid valve (4) is a two-position three-way valve. The pressure port P of the preheating solenoid valve (4) is connected to the pressure oil source, and the working port A is connected to the rod chamber (100) of the oil motor (1).

3. The integrated switching device for the main steam valve of a steam turbine according to claim 1, characterized in that: The unloading valve (9) is a two-way cartridge valve, the quick-closing solenoid valve (8) is a two-position three-way valve, and the pressure port P of the quick-closing solenoid valve (8) is connected to the pressure oil source, the working port A is connected to the control chamber on the unloading valve (9), and the return port T is connected to the drain passage (15).

4. The integrated switching device for the main steam valve of a steam turbine according to claim 2, characterized in that: The first pressure oil circuit (13) also includes a throttle hole (6) disposed between the rod chamber (100) of the oil motor (1) and the preheating solenoid valve (4) through a flow channel. The A port on the unloading valve (9) is connected to the flow channel between the throttle hole (6) and the rod chamber (100) of the oil motor (1).

5. An integrated switching device for a steam turbine main steam valve according to claim 4, characterized in that: The first pressure oil circuit (13) also includes an active test solenoid valve (5) disposed between the throttle orifice (6) and the preheating solenoid valve (4) via a flow channel. The active test solenoid valve (5) is a two-position three-way valve. The pressure port P of the active test solenoid valve (5) is connected to the working port A of the preheating solenoid valve (4). The return port T of the active test solenoid valve (5) is connected to the drain passage (15). The working port A of the active test solenoid valve (5) is connected to the rod chamber (100) of the hydraulic actuator (1). The control system is connected to the active test solenoid valve (5) and is used to control the de-energization and energization of the active test solenoid valve (5).

6. An integrated switching device for a steam turbine main steam valve according to claim 5, characterized in that: The oil pressure source is provided with an oil supply pressure measuring point (12) through the flow channel; the oil discharge pressure measuring point (10) is provided on the flow channel between the rodless chamber (200) of the oil motor (1) and the B port of the unloading valve (9); the rod chamber pressure measuring point (11) and the rod chamber pressure sensor (7) are provided in sequence on the flow channel between the rod chamber (100) of the oil motor (1) and the throttle orifice (6), and the control system is connected to the rod chamber pressure sensor (7).

7. An integrated switching device for a steam turbine main steam valve according to any one of claims 1-6, characterized in that: The displacement sensor (3) is coaxially arranged with the piston rod (16) of the hydraulic motor (1).

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