A structure for improving the control of the intermediate-pressure main steam valve in a steam turbine

Abstract

A structure for improving the control of the intermediate-pressure main steam valve of a steam turbine is disclosed. Currently, there is no connecting pipe between the steam pipes at the outlet of the reheater on the left and right sides of the boiler and the inlet pipes of the intermediate-pressure main steam valve on the left and right sides of the steam turbine. If the feedback sensor of either the left or right side of the intermediate-pressure main steam valve malfunctions, it will trigger a turbine trip, posing a risk of false tripping and making it difficult to effectively guarantee the safety of the unit. This invention includes a feedback device and a protective housing. The protective housing is installed around the feedback device, and its bottom end is fixed to the chassis of the feedback device. Two axially distributed fixing bolts are fixed to the left side wall of the protective housing, and an elongated groove is fixed to the front end of the protective housing. The two fixing bolts are engaged with a connecting plate, and a mounting plate is vertically fixed to the connecting plate. A limit switch is fixed to the mounting plate, and the feedback rod of the limit switch extends into the feedback device from the bottom of the elongated groove. The elongated groove is slidably connected to the trigger rod of the feedback device. This invention is used to improve the control of the intermediate-pressure main steam valve of a steam turbine.

Description

Technical Field

[0001] This utility model relates to a structure for improving the control of the intermediate pressure main steam valve of a steam turbine. Background Technology

[0002] There is no connecting pipe between the steam outlet pipes of the left and right reheaters of the boiler and the inlet pipes of the intermediate pressure main steam valves of the left and right sides of the turbine. If the feedback sensor of either the left or right side intermediate pressure main steam valve malfunctions, it will trigger the turbine to trip, which poses a risk of false tripping and makes it difficult to effectively guarantee the safety of the unit. Utility Model Content

[0003] To address the aforementioned problems, this utility model provides a structure for improving the control of the intermediate-pressure main steam valve in a steam turbine.

[0004] The above objectives are achieved through the following scheme: A structure for improving the control of the intermediate pressure main steam valve of a steam turbine includes a feedback device and a protective housing. The protective housing is installed on the outer periphery of the feedback device. The bottom end of the protective housing is fixed to the chassis of the feedback device. Two axially distributed fixing bolts are fixed on the left side wall of the protective housing. A long strip groove is fixed on the front end of the protective housing. The two fixing bolts are snapped into the connecting plate, the connecting plate is vertically fixed with the mounting plate, the mounting plate is fixed with the limit switch, and the feedback rod of the limit switch extends into the feedback device from the bottom of the elongated groove. The elongated groove is slidably connected to the trigger rod of the feedback device.

[0005] The feedback device includes a valve stem assembly, a chassis, and a top plate. Three support plates are symmetrically distributed between the chassis and the top plate. An A flange is fixed to the lower end of the chassis, and a B flange is fixed to the upper end of the top plate. The upper end of the B flange is fixed to the C flange of the hydraulic actuator. The three support plates are located between the valve stem assembly and the protective housing.

[0006] The valve stem assembly includes a valve stem, a sealing assembly, and a coupling assembly. The upper end of the valve stem is fixed to the oil rod of the hydraulic actuator via the coupling assembly, and the lower end of the valve stem is fixed to the sealing assembly at the point where it passes through the chassis.

[0007] The coupling assembly includes a coupling body and a connecting flange. The coupling body is slidably connected to the central opening of the top plate and the B flange. The lower end of the coupling body is fixed to the connecting flange by connecting bolts. The lower part of the coupling body and the upper part of the connecting flange are provided with internal thread grooves. The two internal thread grooves form an adjustment groove. The adjustment groove is threadedly connected to a valve stem nut. The lower end of the oil rod is fixed to the coupling body, and the upper end of the valve stem is fixed to the valve stem nut. An adjustment block is connected at the connection between the oil rod and the valve stem.

[0008] The upper end of the hydraulic actuator is fixed with a support base, and a magnetostrictive displacement sensor is fixed on the support base. Beneficial effects

[0009] 1. In response to the problem in the existing technology that "there is no connecting pipe from the reheater outlet on the left and right sides of the boiler to the inlet of the intermediate pressure main steam valve of the turbine, and the turbine trips due to the failure of a single feedback sensor", this utility model forms a dual monitoring mechanism through the dual feedback design of limit switch and magnetostrictive displacement sensor. Even if a single sensor fails, the other sensor can still normally provide feedback on the opening and closing status of the intermediate pressure main steam valve, avoiding turbine tripping due to the failure of a single sensor, and significantly improving the reliability and safety of unit operation.

[0010] 2. The magnetostrictive displacement sensor can detect the axial displacement of the oil rod and valve stem in real time, providing accurate valve opening and closing signals for the control system; the limit switch is linked with the valve stem trigger rod through the feedback rod, which can accurately reflect the fully closed state of the valve, and at the same time play a limit protection role, avoiding structural damage caused by valve overtravel, and further improving the accuracy and safety of control.

[0011] 3. The protective housing, through the snap-fit ​​design of the fixing bolts and connecting plate and mounting plate, makes the installation, disassembly and position adjustment of the limit switch more convenient. At the same time, the protective housing provides a closed protective space for internal components, isolating them from external environmental interference. The adjustment groove in the coupling assembly cooperates with the valve stem nut, allowing precise adjustment of the axial position of the valve stem by rotating the valve stem nut, realizing rapid valve calibration. The adjustment block can help fix the relative position of the oil rod and the valve stem, improving connection stability and reducing debugging costs. Attached Figure Description

[0012] Figure 1 This is the front view of the present invention; Figure 2 This is the left view of the present invention; Figure 3 This is a schematic diagram of the feedback device of this utility model; Figure 4 This is a detailed internal view of the valve stem assembly and coupling assembly of this utility model; In the diagram: 1. Flange A; 2. Chassis; 3. Limit switch; 4. Cable A; 5. Mounting plate; 6. Magnetostrictive displacement sensor; 7. Cable B; 8. Support base; 9. Hydraulic actuator housing; 10. Protective housing; 11. Trigger rod; 12. Long slot; 13. Feedback rod; 14. Connecting plate; 15. Fixing bolt; 16. Connecting groove; 17. Feedback device; 18. Valve stem assembly; 19. Coupling assembly; 20. Top plate; 21. Flange B; 22. Flange C; 23. Hydraulic actuator; 24. Valve stem; 25. Sealing assembly; 26. Internal thread groove; 27. Adjustment groove; 28. Valve stem nut; 29. ​​Oil rod; 30. Coupling body; 31. Adjustment block; 32. Connecting bolt; 33. Connecting flange; 34. Support plate. Detailed Implementation

[0013] A structure for improving the control of the intermediate pressure main steam valve of a steam turbine includes a feedback device 17 and a protective housing 10. The protective housing is installed on the outer periphery of the feedback device. The bottom end of the protective housing is fixed on the chassis 2 of the feedback device. Two axially distributed fixing bolts 15 are fixed on the left side wall of the protective housing. A long strip groove 12 is fixed on the front end of the protective housing. The protective shell provides a closed protective space for the internal components, isolating them from external environmental interference; the elongated groove provides an axial sliding channel for the trigger rod and an insertion interface for the limit switch feedback rod, enabling the trigger rod and the limit switch feedback rod to be triggered; the feedback device receives the power transmission of the hydraulic motor and controls the opening and closing of the medium-pressure main steam valve through the movement of the valve stem assembly, while simultaneously linking the magnetostrictive displacement sensor and the limit switch to provide feedback on the opening and closing status of the medium-pressure main steam valve; The two fixing bolts are respectively engaged with the two connecting slots 16 of the connecting plate 14. The connecting plate is vertically fixed with the mounting plate 5. The mounting plate is fixed with the limit switch 3. The feedback rod 13 of the limit switch extends into the feedback device from the bottom of the elongated slot. The limit switch is connected to the trigger rod of the valve stem via a feedback rod to provide feedback on the fully closed state of the medium-pressure main steam valve, thereby preventing the valve from operating beyond its travel range and reducing the risk of unit tripping due to a single sensor failure.

[0014] The elongated groove is slidably connected to the trigger rod 11 of the feedback device.

[0015] The feedback device includes a valve stem assembly 18, a chassis, and a top plate 20. Three support plates 34 are symmetrically distributed between the chassis and the top plate. An A flange 1 is fixed to the lower end of the chassis, and a B flange 21 is fixed to the upper end of the top plate. The upper end of the B flange is fixed to the C flange 22 of the hydraulic actuator 23. The three support plates are located between the valve stem assembly and the protective housing. A hydraulic actuator housing 9 is installed on the outside of the hydraulic actuator and is fixed to the C flange.

[0016] The three support plates serve to separate and protect the structure, enhance its rigidity, prevent interference between the valve stem assembly and the protective shell during movement, and improve the overall vibration resistance.

[0017] The valve stem assembly includes a valve stem 24, a sealing assembly 25, and a coupling assembly 19. The upper end of the valve stem is fixed to the oil rod 29 of the hydraulic actuator via the coupling assembly, and the lower end of the valve stem is fixed to the sealing assembly at the point where it passes through the chassis.

[0018] The coupling assembly includes a coupling body 30 and a connecting flange 33. The coupling body is slidably connected to the central opening of the top plate and the B flange. The lower end of the coupling body is fixed to the connecting flange by connecting bolts 32. The lower part of the coupling body and the upper part of the connecting flange are provided with internal thread grooves 26. The two internal thread grooves form an adjustment groove 27. The adjustment groove is threadedly connected to a valve stem nut 28. The lower end of the oil rod is fixed to the coupling body, and the upper end of the valve stem is fixed to the valve stem nut. An adjustment block 31 is connected at the connection between the oil rod and the valve stem.

[0019] The valve stem nut is rotated to adjust the axial position of the valve stem, thereby calibrating the valve opening. The connecting flange cooperates with the valve stem nut to achieve adjustment. The adjustment block is located at the connection between the oil rod and the valve stem, which helps to fix their relative positions, enhances connection stability, and facilitates locking after adjustment.

[0020] The upper end of the hydraulic actuator is fixed with a support base 8, and the support base is fixed with a magnetostrictive displacement sensor 6. The magnetostrictive displacement sensor accurately detects the axial displacement of the oil rod and valve rod, and provides real-time feedback on the opening degree of the medium-pressure main steam valve, which serves as a feedback signal for the control system to realize the valve opening and closing control.

[0021] The limit switch is connected to cable A 4, and the magnetostrictive displacement sensor is connected to cable B 7.

[0022] Working Principle: This invention employs a dual feedback design of a limit switch and a magnetostrictive displacement sensor to form a dual monitoring mechanism. When the hydraulic actuator drives the valve stem to open and close the intermediate-pressure main steam valve, the magnetostrictive displacement sensor detects the axial displacement of the valve stem in real time and feeds back the valve opening and closing signal. The limit switch, through the feedback rod, contacts the trigger rod on the valve stem to provide feedback on the fully closed state of the valve and prevent overtravel. The two components form a dual feedback mechanism, ensuring that if either sensor fails, the other component can still provide normal feedback on the critical valve status information, preventing the turbine from tripping due to a single sensor failure and ensuring the safe and stable operation of the unit.

Claims

1. A structure for improving the control of the intermediate-pressure main steam valve of a steam turbine, comprising a feedback device and a protective enclosure, characterized in that: The feedback device is equipped with a protective shell, the bottom of which is fixed to the chassis of the feedback device. Two axially distributed fixing bolts are fixed on the left side wall of the protective shell, and a long strip groove is fixed on the front end of the protective shell. The two fixing bolts are snapped into the connecting plate, the connecting plate is vertically fixed with the mounting plate, the mounting plate is fixed with the limit switch, and the feedback rod of the limit switch extends into the feedback device from the bottom of the elongated groove. The elongated groove is slidably connected to the trigger rod of the feedback device.

2. The structure for improving the control of the intermediate-pressure main steam valve of a steam turbine according to claim 1, characterized in that: The feedback device includes a valve stem assembly, a chassis, and a top plate. Three support plates are symmetrically distributed between the chassis and the top plate. An A flange is fixed to the lower end of the chassis, and a B flange is fixed to the upper end of the top plate. The upper end of the B flange is fixed to the C flange of the hydraulic actuator. The three support plates are located between the valve stem assembly and the protective housing.

3. The structure for improving the control of the intermediate-pressure main steam valve of a steam turbine according to claim 2, characterized in that: The valve stem assembly includes a valve stem, a sealing assembly, and a coupling assembly. The upper end of the valve stem is fixed to the oil rod of the hydraulic actuator via the coupling assembly. A trigger rod is fixed to the side of the upper end of the valve stem facing the elongated groove. A sealing assembly is fixed to the lower end of the valve stem where it passes through the chassis.

4. The structure for improving the control of the intermediate-pressure main steam valve of a steam turbine according to claim 3, characterized in that: The coupling assembly includes a coupling body and a connecting flange. The coupling body is slidably connected to the central opening of the top plate and the B flange. The lower end of the coupling body is fixed to the connecting flange by connecting bolts. The lower part of the coupling body and the upper part of the connecting flange are provided with internal thread grooves. The two internal thread grooves form an adjustment groove. The adjustment groove is threadedly connected to a valve stem nut. The lower end of the oil rod is fixed to the coupling body, and the upper end of the valve stem is fixed to the valve stem nut. An adjustment block is connected at the connection between the oil rod and the valve stem.

5. A structure for improving the control of the intermediate-pressure main steam valve of a steam turbine according to claim 4, characterized in that: The upper end of the hydraulic actuator is fixed with a support base, and a magnetostrictive displacement sensor is fixed on the support base.

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