A device and method for assisting online replacement of a servo valve of a governing system of a steam turbine unit

Abstract

The application discloses a device and method for assisting in replacing a servo valve of a regulating system of a steam turbine unit, and relates to the technical field of the regulating system of the steam turbine unit. The device comprises an upper control unit and a lower control unit which are installed between the servo valve and an oil motor. The upper control unit and the lower control unit are communicated through three oil paths. The upper control unit is provided with three manual control on-off valves which correspond to the oil paths respectively. The three manual control on-off valves can control the on-off of the corresponding oil paths respectively. The lower control unit is provided with a two-way plug-in needle valve which can control the communication or cut-off between two oil paths. According to the replacement method based on the device, when the servo valve is replaced, the oil path isolation is strict, and the replacement mode is simple and low in risk.

Description

Technical Field

[0001] This invention relates to the field of turbine generator set regulation system technology, and in particular to a device and method for assisting in the online replacement of servo valves in turbine generator set regulation systems. Background Technology

[0002] Currently, to meet the needs of power grid stability, steam turbine generator sets are required to have the ability to quickly and frequently scale peak loads, which places higher demands on the flexibility and reliability of the turbine unit's regulating system. In China, the regulating system of steam turbine units, especially large steam turbine units, generally adopts the DEH control system, and the electro-hydraulic servo actuator is the most important component of it.

[0003] The electro-hydraulic servo actuator for steam turbines consists of a hydraulic actuator and an operating seat. The amount of steam entering the steam turbine is controlled by adjusting the opening of the regulating valve. The valve opening is driven by the hydraulic actuator, while closing is achieved by the spring force on the operating seat. The balance between these two forces maintains the valve at a specific opening. The function of the electro-hydraulic servo actuator is to control the oil flow into the hydraulic actuator cylinder of the regulating valve, thereby controlling the valve opening. Its core control component is the servo valve.

[0004] A servo valve consists of a torque motor and a two-stage hydraulic amplification and mechanical feedback system. The first-stage hydraulic amplification is a dual-nozzle and baffle system; the second-stage amplification is a spool valve system. As a precision hydraulic component, the servo valve is highly susceptible to jamming if the oil quality is not properly maintained. The servo valve acts as the window controlling the oil inlet and outlet of each regulating valve's hydraulic actuator cylinder during normal operation. If jamming occurs, the regulating valve cylinder will continuously remain in either the inlet or outlet state. When in the outlet state, the regulating valve will remain closed; when in the inlet state, the regulating valve will remain fully open. In both states, the regulating valve loses its regulating function.

[0005] When a servo valve becomes stuck, current technology requires isolating the steam side of the valve for online replacement. This forces the turbine unit to operate under a prolonged period of single-sided steam intake, severely testing the turbine shaft system's capacity. Improper operation during isolation poses a risk of tripping due to excessive turbine shaft vibration. Inadequate oil circuit isolation can also lead to significant control oil leakage, posing serious safety hazards to personnel and equipment. Furthermore, online replacement procedures are cumbersome, time-consuming, and inherently risky. Summary of the Invention

[0006] The purpose of this invention is to provide an apparatus and method for assisting in the online replacement of servo valves in the regulating system of a steam turbine unit, so as to solve the problems existing in the prior art. When replacing the servo valve, the oil circuit is tightly isolated, the replacement method is simple and the risk is low.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides a device for assisting in the online replacement of servo valves in the regulating system of a steam turbine unit, comprising an upper control unit and a lower control unit. The upper control unit and the lower control unit are connected by three oil circuits. The upper control unit is equipped with three manually controlled on / off valves corresponding to the oil circuits, and the three manually controlled on / off valves can control the on / off state of the corresponding oil circuits respectively. The lower control unit is equipped with a two-way cartridge needle valve, which can control the connection or disconnection between two of the oil circuits.

[0009] Optionally, the upper control unit and the lower control unit are used to install between the servo valve and the hydraulic actuator. The installation interface of this invention is exactly the same as the servo valve installation interface. The device of this invention can be installed at the original servo valve position, and then the servo valve can be installed on the device of this invention. Therefore, it can be installed without additional changes to the original system installation design, which is highly applicable and convenient to use. The three oil circuits include a working oil circuit, an inlet oil circuit, and a return oil circuit. One end of the working oil circuit, the inlet oil circuit, and the return oil circuit is connected to the working oil port, the inlet oil port, and the return oil port of the servo valve through the top opening of the upper control unit, respectively. The other end of the working oil circuit, the inlet oil circuit, and the return oil circuit is connected to the hydraulic actuator inlet chamber, the inlet end, and the return end through the bottom opening of the lower control unit, respectively. The two-way cartridge needle valve can control the connection or disconnection between the working oil circuit and the inlet oil circuit.

[0010] Optionally, the upper control unit includes an upper control valve body, and the manual control shut-off ball valve is installed on the upper control valve body. The manual control shut-off ball valve includes two valve seat sealing bowls fixedly disposed in the oil circuit. The valve seat sealing bowls have openings at their ends that communicate with the oil circuit. A ball is disposed between the two valve seat sealing bowls. A valve stem shaft is fixedly connected to the ball. The valve stem shaft sealably penetrates the side wall of the oil circuit and the upper control valve body. A through hole is provided in the ball. When the valve stem shaft rotates and drives the ball to rotate until the center line of its through hole is aligned with the center line of the two valve seat sealing bowls, the through hole communicates with the opening of the valve seat sealing bowl, and the oil circuit is in a fully open state. When the valve stem shaft rotates and drives the ball to rotate until the center line of its through hole is perpendicular to the center line of the two valve seat sealing bowls, the oil circuit is in a fully closed state. The oil circuit is simple and reliable to open and close. There is no throttling in the open state, and there is no risk of control oil contamination.

[0011] Optionally, the valve stem shaft sidewall is sealed to the upper control valve body by a valve stem seal; the manual control shut-off ball valve is fixed to the upper control valve body by a positioning sleeve, and positioning sleeve seals are installed on the bottom and outside of the positioning sleeve.

[0012] Optionally, a stop pad is fixedly installed at one end of the valve stem shaft outside the upper control valve body. A positioning pin is fixedly provided on the side of the upper control valve body near the valve stem shaft. The positioning pin can limit the rotation angle of the stop pad. The stop pad rotates together with the valve stem shaft. The rotation angle of the stop pad is controlled by the positioning pin, thereby controlling the rotation angle of the valve stem shaft. The maximum rotation angle of the valve stem shaft is 90 degrees. The stop pad has a semi-circular structure. The radius of the stop pad is larger than the distance between the positioning pin and the valve stem shaft. A limiting groove is provided at the end face of the stop pad. So, during rotation, when the positioning pin is engaged with the limiting groove, the stop pad is limited. When rotating in the opposite direction to engage with the positioning pin in another limiting groove, the stop pad is limited in another direction.

[0013] Optionally, the lower control unit includes a lower control valve body, and the two-way cartridge needle valve is rotatably and sealed on the lower control valve body. Under normal operating conditions, this needle valve is closed. When replacing the servo valve, this needle valve can be manually opened to force oil to enter the working oil circuit through the oil inlet circuit.

[0014] This invention also provides a method for assisting in the online replacement of servo valves in the regulating system of a steam turbine unit, comprising the following steps:

[0015] Step 1: Install the upper control unit and the lower control unit between the hydraulic actuator and the servo valve according to the design requirements;

[0016] Step 2: When the unit is running normally, open the three oil circuits of the upper control unit normally and close the two-way needle valve of the lower control unit.

[0017] Step 3: When the turbine unit regulation system malfunctions, determine whether the servo valve is stuck by observing the symptoms. At this time, the turbine inlet regulating valve is either fully closed or fully open, and the regulating valve has lost its regulating function.

[0018] Step 4: When the servo valve is stuck, first deactivate the automatic control mode of the regulating valve to force the regulating valve command to match the feedback.

[0019] Step 5: If the regulating valve is in the closed state, completely close the three oil circuits of the upper control unit; if the regulating valve is in the fully open state, in addition to completely closing the three oil circuits of the upper control unit, you also need to manually open the two-way needle valve of the lower control unit.

[0020] Step 6: Remove the faulty servo valve and ensure the regulating valve is either closed or fully open;

[0021] Step 7: Replace the servo valve online;

[0022] Step 8: After the servo valve is replaced, if the two-way cartridge needle valve of the lower control unit is in the manually open state, first manually close it, and then open the three oil circuits of the upper control unit.

[0023] Step 9: After completion, release the forced state of the regulating valve and restore the automatic operation state.

[0024] Optionally, the opening sequence of the three oil circuits in step eight is: return oil circuit, inlet oil circuit, and working oil circuit.

[0025] The present invention achieves the following technical effects compared to the prior art:

[0026] This invention is easy to install, requires no design changes to the installation interface, controls without throttling, and eliminates the risk of control oil contamination. Furthermore, the online replacement method for servo valves proposed in this invention allows for online replacement of servo valves when they become stuck in the turbine unit regulating system. The replacement process is efficient and safe, greatly improving the flexibility, reliability, and safety of the turbine unit regulating system. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram showing the installation of the device, servo valve, and hydraulic actuator of the present invention.

[0029] Figure 2 This is an external view of the device of the present invention;

[0030] Figure 3 This is an external view of the control unit on the device of the present invention;

[0031] Figure 4 This is a top view of the control unit on the device of the present invention;

[0032] Figure 5 This is a side view of the control unit on the device of the present invention;

[0033] Figure 6 for Figure 4 AA cross-section view;

[0034] Figure 7 For the present invention Figure 4 BB cross-section;

[0035] Figure 8 This is an external view of the control unit of the device of the present invention;

[0036] Figure 9 This is a top view of the lower control unit of the device of the present invention;

[0037] Figure 10 for Figure 9 AA cross-section view;

[0038] Figure 11 for Figure 9 BB cross-section;

[0039] Figure 12 This is a schematic diagram of the device of the present invention;

[0040] Figure 13 This is the normal operating state after the device of the present invention is installed in the embodiment;

[0041] Figure 14 The example is in a fault state where the servo valve is stuck, causing the steam inlet valve to be fully closed;

[0042] Figure 15 The example is in a fault state where the servo valve is stuck, causing the steam inlet valve to be fully open;

[0043] Figure 16 When the servo valve is stuck and the steam inlet valve is fully closed, this is the handling state of the device of the present invention when the servo valve is replaced online;

[0044] Figure 17 When the servo valve is stuck and the steam inlet valve is fully open, this is the handling state of the device of the present invention when the servo valve is replaced online.

[0045] Figure 18 In the example, when the servo valve is stuck and the steam inlet valve is fully closed, the state after handling the situation using the device of the present invention and removing the faulty servo valve online;

[0046] Figure 19 In the example, when the servo valve is stuck and the steam inlet valve is fully open, the state after handling the situation using the device of the present invention and removing the faulty servo valve online;

[0047] Explanation of reference numerals in the attached drawings: 100-Servo valve, 200-Auxiliary online replacement device for servo valves in the turbine generator set regulating system, 300-Hydraulic actuator, 01-Upper control unit, 02-Lower control unit, 11-Upper control valve body, 12-Valve stem shaft, 13-Valve stem seal, 14-Ball, 15-Valve seat seal bowl, 16-Positioning pin, 17-Stop pad, 18-Positioning sleeve, 19-Positioning sleeve seal, 21-Lower control valve body, 22-Two-way cartridge needle valve. Detailed Implementation

[0048] 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.

[0049] The purpose of this invention is to provide an apparatus and method for assisting in the online replacement of servo valves in the regulating system of a steam turbine unit, so as to solve the problems existing in the prior art. When replacing the servo valve, the oil circuit is tightly isolated, the replacement method is simple and the risk is low.

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Reference Appendix Figure 1 ~Attached Figure 19 As shown, the present invention provides a device 200 for assisting in online replacement of servo valves in the regulating system of a steam turbine unit, including an upper control unit 01 and a lower control unit 02. The upper control unit 01 and the lower control unit 02 are connected by three oil circuits. The upper control unit 01 is provided with three manually controlled on / off valves corresponding to the oil circuits, and the three manually controlled on / off valves can control the on / off of the corresponding oil circuits respectively. The lower control unit 02 is provided with a two-way cartridge needle valve 22, which can control the connection or disconnection between two of the oil circuits.

[0052] Specifically, the present invention is installed on the hydraulic actuator 300 (hydraulic circuit block schematic), and then the servo valve 100 is installed on the device of the present invention. In this embodiment, the servo valve 100 is model MOOG G761.

[0053] Further preferably, the upper control unit 01 of the present invention includes an upper control valve body 11. The upper control valve body 11 has three control oil passages formed by drilling: an inlet oil passage P, a working oil passage A, and a return oil passage T. For each control oil passage, a set of manually controlled shut-off ball valves is installed inside the valve body. Each set of manually controlled shut-off ball valves includes a valve stem shaft 12, a ball 14, a valve seat sealing bowl 15, a positioning pin 16, and a stop washer 17. The valve stem shaft 12 is connected to the ball 14, so the rotation of the valve stem shaft 12 can drive the ball 14 to rotate. The ball 14 has a through hole, and valve seat sealing bowls 15 are provided on both sides of the ball 14. When the valve stem shaft 12 rotates, causing the ball 14 to rotate until the center line of its through hole is aligned with the center line of the two valve seat sealing bowls 15, the passage is fully open. When the valve stem shaft 12 rotates, causing the ball 14 to rotate until the center line of its through hole is perpendicular to the center line of the two valve seat sealing bowls 15, the passage is fully closed. The valve stem shaft 12 is sealed to the upper control valve body 11 by a valve stem seal 13. A manual control shut-off ball valve is fixed inside the upper control valve body 11 by a positioning sleeve 18. Positioning sleeve seals 19 are installed on the bottom and outside of the positioning sleeve 18. A stop washer 17 is mounted on the valve stem shaft 12 and rotates together with it. The rotation angle of the stop washer 17 is controlled by a positioning pin 16, thereby controlling the rotation angle of the valve stem shaft 12. The maximum rotation angle of the valve stem shaft 12 is 90 degrees.

[0054] The lower control unit 02 includes a lower control valve body 21, on which a two-way cartridge needle valve 22 is mounted.

[0055] The specific implementation method of this invention is as follows:

[0056] Step 1: As per design requirements, the device of this invention is installed on the hydraulic actuator 300 (hydraulic circuit block diagram), and then the servo valve 100 is installed on the device of this invention.

[0057] Step 2: During normal unit operation, open the three control oil circuits (inlet P, working oil circuit A, and return oil circuit T) of the control unit on the invention device. Close the two-way needle valve 22 of the lower control unit of the invention device. Figure 13 As shown.

[0058] Step 3: When a fault occurs in the turbine unit's regulating system, determine whether the servo valve is stuck by observing the symptoms. In this case, the turbine inlet regulating valve will be either completely closed or... Figure 14 As shown, or in a fully open state, such as Figure 15 As shown, all regulating valves have lost their regulating function.

[0059] Step 4: When the servo valve 100 is stuck, the DEH system first deactivates the automatic control mode of the steam inlet valve, forcing the steam inlet valve command to be consistent with the feedback, to prevent the steam inlet valve from going out of control and suddenly opening and closing drastically.

[0060] Step 5: If the steam inlet regulating valve is in the closed state, the three control oil circuits of the control unit on the invention device—the inlet oil circuit P, the working oil circuit A, and the return oil circuit T—can be completely closed. Figure 16 As shown; when the steam inlet regulating valve is fully open, in addition to the aforementioned operations, the two-way cartridge needle valve 22 of the control unit under the invention device should also be manually opened. This ensures that the steam inlet regulating valve remains fully open during the replacement of the servo valve, avoiding disturbance. Figure 17 As shown.

[0061] Step Six: Remove the faulty servo valve. The steam inlet regulating valve should be in the closed position. Figure 18 As shown; the steam inlet regulating valve is in the fully open state, as... Figure 19 As shown.

[0062] Step 7: Replace the servo valve online.

[0063] Step 8: After replacing the servo valve, if the two-way needle valve of the lower control unit of the invention device is in the manually open state, first manually close it. Then manually open the three control oil circuits of the upper control unit: the inlet oil circuit P, the working oil circuit A, and the return oil circuit T. The order is: return oil circuit T, inlet oil circuit P, and finally working oil circuit A. The final state is as follows: Figure 13 As shown.

[0064] Step 9: After completion, release the forced state of the steam inlet valve and restore the automatic operation state of the DEH system.

[0065] In the description of this invention, it should be noted that the terms "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A device for assisting in the online replacement of servo valves in the regulating system of a steam turbine unit, characterized in that: It includes an upper control unit and a lower control unit, which are connected by three oil circuits. The upper control unit is equipped with three manually controlled on / off valves corresponding to the oil circuits, and the three manually controlled on / off valves can control the on / off of the corresponding oil circuits respectively. The lower control unit is equipped with a two-way cartridge needle valve, which can control the connection or disconnection between two of the oil circuits. The upper control unit and lower control unit are installed between the servo valve and the hydraulic actuator; the three oil circuits include a working oil circuit, an inlet oil circuit, and a return oil circuit. One end of the working oil circuit, inlet oil circuit, and return oil circuit is connected to the working oil port, inlet oil port, and return oil port of the servo valve respectively through the top opening of the upper control unit. The other end of the working oil circuit, inlet oil circuit, and return oil circuit is connected to the hydraulic actuator's oil inlet chamber, inlet end, and return end respectively through the bottom opening of the lower control unit; the two-way cartridge needle valve can control the connection or disconnection between the working oil circuit and the inlet oil circuit; The upper control unit includes an upper control valve body, and a manual control shut-off ball valve is installed on the upper control valve body. The manual control shut-off ball valve includes two valve seat sealing bowls fixedly disposed in the oil circuit. The valve seat sealing bowls have openings at their ends that connect to the oil circuit. A ball is disposed between the two valve seat sealing bowls. A valve stem shaft is fixedly connected to the ball. The valve stem shaft sealably penetrates the side wall of the oil circuit and the upper control valve body. A through hole is provided in the ball. When the valve stem shaft rotates and drives the ball to rotate until the center line of its through hole is aligned with the center line of the two valve seat sealing bowls, the oil circuit is in a fully open state. When the valve stem shaft rotates and drives the ball to rotate until the center line of its through hole is perpendicular to the center line of the two valve seat sealing bowls, the oil circuit is in a fully closed state.

2. The device for assisting in online replacement of servo valves in the turbine generator set regulating system according to claim 1, characterized in that: The valve stem shaft sidewall is sealed to the upper control valve body by a valve stem seal; the manual control shut-off ball valve is fixed to the upper control valve body by a positioning sleeve, and positioning sleeve seals are installed on the bottom and outside of the positioning sleeve.

3. The device for assisting in online replacement of servo valves in the turbine generator set regulating system according to claim 1, characterized in that: A stop pad is fixedly installed at one end of the valve stem shaft outside the upper control valve body. A positioning pin is fixedly provided on the side of the upper control valve body near the valve stem shaft. The positioning pin can limit the rotation angle of the stop pad.

4. The device for assisting in online replacement of servo valves in the turbine generator set regulating system according to claim 1, characterized in that: The lower control unit includes a lower control valve body, and the two-way cartridge needle valve is rotatably mounted on the lower control valve body.

5. A method for auxiliary online replacement of servo valves in a turbine generator set regulating system, based on the apparatus for auxiliary online replacement of servo valves in a turbine generator set regulating system as described in any one of claims 1 to 4, characterized in that: The steps include the following: Step 1: Install the upper control unit and the lower control unit between the hydraulic actuator and the servo valve according to the design requirements; Step 2: When the unit is running normally, open the three oil circuits of the upper control unit normally and close the two-way needle valve of the lower control unit. Step 3: When the turbine unit regulation system malfunctions, determine whether the servo valve is stuck by observing the symptoms. At this time, the turbine inlet regulating valve is either fully closed or fully open, and the regulating valve has lost its regulating function. Step 4: When the servo valve is stuck, first deactivate the automatic control mode of the regulating valve to force the regulating valve command to match the feedback. Step 5: If the regulating valve is in the closed state, completely close the three oil circuits of the upper control unit; if the regulating valve is in the fully open state, in addition to completely closing the three oil circuits of the upper control unit, you also need to manually open the two-way needle valve of the lower control unit. Step 6: Remove the faulty servo valve and ensure the regulating valve is either closed or fully open; Step 7: Replace the servo valve online; Step 8: After the servo valve is replaced, if the two-way cartridge needle valve of the lower control unit is in the manually open state, first manually close it, and then open the three oil circuits of the upper control unit. Step 9: After completion, release the forced state of the regulating valve and restore the automatic operation state.

6. The method for assisted online replacement of servo valves in the turbine generator regulating system according to claim 5, characterized in that: In step eight, the opening sequence of the three oil circuits is: return oil circuit, inlet oil circuit, and working oil circuit.

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