A discharge pressure regulating water inlet valve for large hydraulic turbine and its use method

Abstract

The present invention discloses a flow-discharge and pressure-regulating water inlet valve for a large-scale hydraulic turbine and a method for using the same. The valve comprises an outer valve body and an inner valve body. The outer valve body is provided with a water inlet and a water outlet at both ends, respectively. The inner valve body is connected to the outer valve body through a guide vane. The inner valve body is provided with a main valve core sliding near the outlet end. The main valve core is used to seal the outlet and adjust the water output. The main valve core or the side wall of the outer valve body is provided with a flow-discharge mechanism for flow discharge. The water inlet valve is divided into a built-in flow-discharge type water inlet valve and a side-mounted flow-discharge type water inlet valve. The valve has four modes: a fully closed working state of the valve; a partially open working state of the valve; a fully open working state of the valve; a normal working state of the valve when the unit is shut down in an emergency; and a state in which the flow-discharge valve is open when the unit is shut down in an emergency. The water inlet valve of the present invention adopts a direct current internal control structure, has good flow patterns, can realize two-way flow, has strong adjustment capabilities, and can realize dynamic water opening and closing.

Description

Technical Field

[0001] The present invention relates to the technical field of water turbines, and in particular to a discharge pressure regulating water inlet valve for a large water turbine and a use method thereof. Background Art

[0002] Currently, the starting method for medium- and large-scale Francis reversible turbine generator sets, where the motor is powered directly from the grid during pump rotation, significantly impacts the grid. Typically, the unit must be cranked up to synchronous speed and then connected to the grid simultaneously. This requires expensive starting equipment, complex operating procedures, and the additional equipment also takes up a considerable amount of space. Commonly used methods include frequency converter starting and back-to-back starting. Frequency converters generate harmonics, becoming a source of harmonics in the grid system and causing voltage distortion in the auxiliary power system. Back-to-back starting requires dedicated excitation equipment, a dedicated starting busbar, switchgear, and additional generator sets. The starting process is complex and can prevent the last unit in the power station from starting, requiring additional starting equipment.

[0003] The turbine inlet valves of existing hydropower stations mainly include four types: ball valves, butterfly valves, gate valves and cylinder valves. The above valves have the following disadvantages as turbine inlet valves:

[0004] 1. Ball valves, gate valves, butterfly valves, and cartridge valves have only two states: fully open and fully closed. They cannot be used to regulate water inlet flow. Using them as flow control valves will increase valve erosion, disrupt water flow stability, and cause excessive hydraulic loss, which can cause unit vibration.

[0005] 2. The sealing performance of ball valves and butterfly valves is poor, and the torque required for switching is large.

[0006] 3. Ball valves and butterfly valves are for one-way or two-way flow inlet and have no discharge and pressure regulating function.

[0007] 4. Power stations with long water pipelines generally have surge tanks, which are difficult to locate and have high construction costs. Summary of the Invention

[0008] The present invention aims to solve the problems of the existing turbine water inlet valve being unable to adjust the flow and having no discharge and pressure regulating function, and provides a discharge and pressure regulating water inlet valve for a large turbine and a method of using the same. The water inlet valve is divided into a built-in discharge type water inlet valve (the valve has a discharge mechanism for discharge on the main valve core) and a side discharge type water inlet valve (the valve has a discharge mechanism for discharge on the outer valve body). The valve has four modes: fully closed working state; partially open working state (this state is used to adjust the flow); fully open working state; fully open working state, the discharge valve is open when the unit is shut down in an emergency.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A discharge and pressure-regulating water inlet valve for a large hydraulic turbine comprises an outer valve body and an inner valve body, wherein the outer valve body is provided with a water inlet and a water outlet at both ends respectively, the inner valve body is connected to the outer valve body via a guide vane, the inner valve body is provided with a main valve core slidingly arranged near the water outlet end, the main valve core is used to block the water outlet and adjust the water output, and a discharge mechanism for discharge is provided on the main valve core or the side wall of the outer valve body.

[0011] Preferably, a main valve core sliding groove is provided at the upper end of the inner valve body, and the main valve core is slidably arranged in the main valve core sliding groove.

[0012] Preferably, the main valve core is connected to a first-stage piston assembly, and the first-stage piston assembly is slidably arranged in the main valve core.

[0013] Preferably, the first-stage piston assembly includes a first-stage piston rod, a first-stage piston connected to one end of the first-stage piston rod, and the other end of the first-stage piston rod is connected to the main valve core. The first-stage piston is located in the first-stage operating oil chamber in the main valve core, and operating oil pipes are provided on the first-stage operating oil chambers on both sides of the first-stage piston.

[0014] Preferably, a balancing sleeve is further provided on the first-stage piston rod.

[0015] Preferably, the inner valve body is provided with an arc-shaped tail cover near the water inlet end.

[0016] Preferably, the discharge mechanism includes a discharge valve for sealing a discharge port and regulating the amount of discharge. The discharge port is disposed on the outer valve body, and the discharge valve is connected to a telescopic assembly, wherein the discharge valve is slidably disposed. The telescopic assembly includes a connector connected to the discharge valve, a telescopic member, and a driving member for driving the telescopic member to extend and retract. The telescopic member drives the connector to move. The telescopic member is disposed near the outer wall of the outer valve body to achieve sealing.

[0017] Preferably, the discharge mechanism includes a secondary valve core and a secondary piston assembly, the secondary valve core is connected to the secondary piston assembly, a reflux chamber is provided between the secondary valve core and the secondary piston assembly, the reflux chamber is connected to the reflux pipe, the reflux pipe passes through the inner valve body and the outer valve body, and the secondary piston assembly is slidably arranged in the primary piston rod.

[0018] Preferably, a reflux port is provided in the middle of the main valve core, the reflux port is communicated with the reflux cavity, a secondary valve core is slidably provided in the reflux port, and the secondary valve core is used to block the reflux port to adjust the reflux amount.

[0019] Preferably, the secondary piston assembly includes a secondary piston rod, which is connected to the secondary valve core. The secondary piston rod is also sleeved with a secondary piston. The secondary piston is located in the secondary operating oil chamber in the primary piston rod, and operating oil pipes are provided on the secondary operating oil chambers on both sides of the secondary piston.

[0020] A method for using a discharge pressure regulating water inlet valve for a large hydraulic turbine includes the following use states:

[0021] (1) Valve fully closed: The discharge mechanism is closed, and the first-stage piston assembly drives the main valve body to move until the main valve body completely blocks the water outlet;

[0022] (2) Partial opening of the valve: the discharge mechanism is closed, and the first-stage piston assembly drives the main valve body to move so that there is a certain gap between the main valve body and the water outlet;

[0023] (3) Valve fully open: the discharge mechanism is closed, and the first-stage piston assembly drives the main valve body to move until the main valve body stops moving;

[0024] (4) The valve is fully open and working normally. When the unit is shut down in an emergency, the relief valve is open: the first-stage piston assembly drives the main valve body to move until the main valve body stops moving, and the relief mechanism is opened.

[0025] When the drainage mechanism of the built-in relief type water inlet valve is closed (the valve is provided with a drainage mechanism for drainage for the main valve core), oil needs to be supplied from the operating oil pipe near the water inlet end of the secondary operating oil chamber, and oil needs to be discharged from the operating oil pipe near the water outlet end of the secondary operating oil chamber. Under the action of the operating oil, the secondary piston drives the secondary piston to slide from the water inlet end to the water outlet end, and the secondary piston drives the secondary piston rod and the secondary valve core to slide from the water inlet end to the water outlet end until the secondary valve core completely blocks the return port.

[0026] The external discharge type water inlet valve (the valve has an outer valve body with a discharge mechanism for discharge) has a discharge mechanism that is closed. The driving part needs to drive the contraction part to extend, and the connecting part on the contraction part drives the discharge valve to slide, so that the discharge valve completely blocks the discharge port.

[0027] The first-stage piston assembly drives the main valve body to move until the main valve body completely blocks the water outlet. This requires oil to flow into the first-stage operating oil chamber from the operating oil pipe near the water inlet end, and oil to flow out of the first-stage operating oil chamber from the operating oil pipe near the water outlet end. Under the action of the operating oil, the first-stage piston drives the first-stage piston to slide from the water inlet end to the water outlet end. The first-stage piston drives the first-stage piston rod and the main valve core to slide from the water inlet end to the water outlet end until the main valve core completely blocks the water outlet.

[0028] For the built-in relief type water inlet valve (the valve is provided with a relief mechanism for relief for the main valve core), the relief mechanism is opened, which requires oil to flow out of the operating oil pipe near the water inlet end of the secondary operating oil chamber, and oil to flow into the operating oil pipe near the water outlet end of the secondary operating oil chamber. Under the action of the operating oil, the secondary piston drives the secondary piston to slide from the water outlet end to the water inlet end, and the secondary piston drives the secondary piston rod and the secondary valve core to slide from the water outlet end to the water inlet end until the secondary valve core stops moving.

[0029] The external discharge type water inlet valve (the valve is a valve with a discharge mechanism for discharge on the outer valve body) opens the discharge mechanism, which requires the driving part to drive the contraction part to contract, and the connecting part on the contraction part drives the discharge valve to slide, so that the discharge valve completely leaves the discharge port.

[0030] The beneficial effects of this technical solution are as follows:

[0031] The present invention provides a pressure-relief inlet valve for large hydraulic turbines. This valve is pressure-resistant and suitable for all types of hydraulic turbines, particularly those with ultra-high heads of 500 m and above. The inlet valve utilizes a direct current internal control structure, resulting in a favorable flow pattern and bidirectional flow. Its strong regulating capability allows for dynamic water opening and closing.

[0032] 2. The present invention provides a discharge and pressure-regulating water inlet valve for a large hydraulic turbine. As the main valve of a conventional hydraulic turbine, the valve can have a full-time self-closing tendency. In the event of failure of the oil pressure device, the main valve can have a self-closing tendency and close slowly to ensure the safety of the power station.

[0033] 3. The present invention provides a discharge and pressure regulating water inlet valve for a large turbine. The valve can provide flow to the turbine with a small opening, low flow, and for a long time, and can achieve the functional replacement of eliminating the bypass pipeline.

[0034] 4. The present invention provides a discharge and pressure-regulating water inlet valve for a large turbine. By adjusting the opening between the needle valve core and the valve, it can complete the basic opening and closing functions of the turbine water inlet valve. At the same time, through the adjustment and coordination of the valve, it can achieve precise control of the flow rate. The water inlet flow rate can be adjusted accordingly according to different working conditions, and the function of the turbine water guide mechanism can be replaced.

[0035] Fifth, the present invention provides a large-scale hydraulic turbine discharge and pressure-regulating inlet valve. The main valve, discharge valve, and piping are integrated into a single structure. The discharge and pressure-regulating piping can be internally or side-mounted. During an emergency or accident shutdown, the discharge and pressure-regulating piping opens, ensuring that the unit meets regulation requirements, resulting in significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural diagram of the built-in leakage-type water inlet valve of the present invention when the valve is fully opened;

[0037] Figure 2 This is a structural diagram of the built-in discharge type water inlet valve of the present invention in a fully open normal working state and the discharge valve in an open state during emergency shutdown of the unit;

[0038] Figure 3 This is a structural diagram of the external leakage-type water inlet valve of the present invention when the valve is fully closed;

[0039] Figure 4This is a structural diagram of the external relief type water inlet valve of the present invention in a fully open state during normal operation and the relief valve in an open state during emergency shutdown of the unit;

[0040] Among them: 1. Outer valve body; 2. Inner valve body; 3. Water inlet; 4. Water outlet; 5. Guide vane; 6. Main valve core; 7. Discharge mechanism; 711. Discharge valve; 712. Telescopic part; 713. Connecting part; 715. Driving part; 716. Discharge port; 721. Secondary valve core; 722. Secondary piston assembly; 723. Return port; 724. Secondary piston rod; 725. Secondary piston; 726. Secondary operating oil chamber; 727. Return pipe; 728. Return chamber; 8. Main valve core sliding groove; 9. First-stage piston assembly; 91. First-stage piston rod; 92. First-stage piston; 93. First-stage operating oil chamber; 10. Balance sleeve; 11. Arc-shaped tail cover; 12. Operating oil pipe. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0042] It should be noted that when a component is referred to as being “mounted on,” “fixed on,” or “disposed on” another component, it may be directly on the other component or there may be an intermediate component. When a component is referred to as being “connected to” another component, it may be directly connected to the other component or there may be an intermediate component.

[0043] It should also be noted that the directional terms such as left, right, up, and down in the embodiments of the present invention are merely relative concepts or are based on the normal use status of the product and should not be considered as restrictive.

[0044] Example 1

[0045] like Figure 1-Figure 4 As shown, a flow-relief and pressure-regulating inlet valve for a large hydraulic turbine is provided. This inlet valve is a built-in flow-relief type inlet valve, comprising an outer valve body 1 and an inner valve body 2. The outer valve body 1 is provided with an inlet 3 and an outlet 4 at both ends, respectively. The inner valve body 2 is connected to the outer valve body 1 through a guide vane 5. A main valve core 6 is slidingly provided near the end of the inner valve body 2 near the outlet 4. The main valve core 6 is used to block the outlet 4 and adjust the water output. A discharge mechanism 7 for discharge is provided on the main valve core 6 or the side wall of the outer valve body 1.

[0046] The upper end of the inner valve body 2 is provided with a main valve core sliding groove 8 , and the main valve core 6 is slidably arranged in the main valve core sliding groove 8 .

[0047] The main valve core 6 is connected to the first-stage piston assembly 9 , and the first-stage piston assembly 9 is slidably arranged in the main valve core 6 .

[0048] Among them, the first-level piston assembly 9 includes a first-level piston rod 91, a first-level piston 92 connected to one end of the first-level piston rod 91, and the other end of the first-level piston rod 91 is connected to the main valve core 6. The first-level piston 92 is located in the first-level operating oil chamber 93 in the main valve core 6, and the first-level operating oil chambers 93 on both sides of the first-level piston 92 are provided with operating oil pipes 12.

[0049] Wherein, a balancing sleeve 10 is further provided on the primary piston rod 91 .

[0050] Wherein, the inner valve body 2 is provided with an arc-shaped tail cover 11 near the end of the water inlet 3 .

[0051] The discharge mechanism 7 includes a discharge valve 711, which is used to block a discharge port 716 to regulate the amount of discharge. The discharge port 716 is provided on the outer valve body 1. The discharge valve 711 is connected to a telescopic assembly and is slidably arranged. The telescopic assembly includes a connector 713 connected to the discharge valve 711, a telescopic member 712, and a driving member 715 that drives the telescopic member 712 to extend and retract. The telescopic member 712 drives the connector 713 to move. The telescopic member 712 is positioned close to the outer wall of the outer valve body 1 to achieve a seal.

[0052] Example 2

[0053] The difference between this embodiment and embodiment 1 is that the discharge mechanism 7 includes a secondary valve core 721 and a secondary piston assembly 722, the secondary valve core 721 is connected to the secondary piston assembly 722, a reflux chamber 726 is provided between the secondary valve core 721 and the secondary piston assembly 722, the reflux chamber 726 is connected to the reflux pipe 727, the reflux pipe 727 passes through the inner valve body 2 and the outer valve body 1, and the secondary piston assembly 722 is slidably provided in the primary piston rod 91.

[0054] A reflux port 723 is provided in the middle of the main valve core 6 , and the reflux port 723 is connected to the reflux chamber 726 . A secondary valve core 721 is slidably provided in the reflux port 723 , and the secondary valve core 721 is used to block the reflux port 723 to adjust the reflux amount.

[0055] Among them, the secondary piston assembly 722 includes a secondary piston rod 724, which is connected to the secondary valve core 721. The secondary piston rod 724 is also sleeved with a secondary piston 725. The secondary piston 725 is located in the secondary operating oil chamber 726 in the primary piston rod 91, and the secondary operating oil chambers 726 on both sides of the secondary piston 725 are provided with operating oil pipes 12.

[0056] A method for using a discharge pressure regulating water inlet valve for a large hydraulic turbine includes the following use states:

[0057] (1) Valve fully closed: the discharge mechanism 7 is closed, and the first-stage piston assembly 9 drives the main valve body to move until the main valve body completely blocks the water outlet 4;

[0058] (2) Partial opening of the valve: the discharge mechanism 7 is closed, and the first-stage piston assembly 9 drives the main valve body to move so that there is a certain gap between the main valve body and the water outlet 4;

[0059] (3) Valve fully open: the discharge mechanism 7 is closed, and the first-stage piston assembly 9 drives the main valve body to move until the main valve body stops moving;

[0060] (4) The valve is fully open and working normally. When the unit is shut down in an emergency, the relief valve 711 is in the open state: the first-stage piston assembly 9 drives the main valve body to move until the main valve body stops moving, and the relief mechanism 7 is opened.

[0061] The built-in leakage type water inlet valve (the valve is provided with a leakage mechanism 7 for leakage for the main valve core 6) has the leakage mechanism 7 closed, which requires the secondary operating oil chamber 726 to enter the operating oil pipe 12 near the water inlet 3 end, and the secondary operating oil chamber 726 to exit the operating oil pipe 12 near the water outlet 4 end. Under the action of the operating oil, the secondary piston 725 drives the secondary piston 725 to slide from the water inlet 3 end to the water outlet 4 end, and the secondary piston 725 drives the secondary piston rod 724 and the secondary valve core 721 to slide from the water inlet 3 end to the water outlet 4 end until the secondary valve core 721 completely blocks the return port 723.

[0062] The external leakage type water inlet valve (the valve is an outer valve body 1 provided with a leakage mechanism 7 for leakage) is closed, and the driving part 715 is required to drive the contraction part to extend, and the connecting part 713 on the contraction part drives the leakage valve 711 to slide, so that the leakage valve 711 completely blocks the leakage port 716.

[0063] The first-stage piston assembly 9 drives the main valve body to move until the main valve body completely blocks the water outlet 4. The first-stage operating oil chamber 93 needs to have oil flowing into the operating oil pipe 12 near the water inlet 3 end, and the first-stage operating oil chamber 93 needs to have oil flowing out of the operating oil pipe 12 near the water outlet 4 end. Under the action of the operating oil, the first-stage piston 92 drives the first-stage piston 92 to slide from the water inlet 3 end to the water outlet 4 end. The first-stage piston 92 drives the first-stage piston rod 91 and the main valve core 6 to slide from the water inlet 3 end to the water outlet 4 end until the main valve core 6 completely blocks the water outlet 4.

[0064] The built-in leakage type water inlet valve (the valve is provided with a leakage mechanism 7 for leakage for the main valve core 6) has the leakage mechanism 7 opened, which requires the secondary operating oil chamber 726 to discharge oil from the operating oil pipe 12 near the water inlet 3 end, and the secondary operating oil chamber 726 to enter oil from the operating oil pipe 12 near the water outlet 4 end. Under the action of the operating oil, the secondary piston 725 drives the secondary piston 725 to slide from the water outlet 4 end to the water inlet 3 end, and the secondary piston 725 drives the secondary piston rod 724 and the secondary valve core 721 to slide from the water outlet 4 end to the water inlet 3 end until the secondary valve core 721 stops moving.

[0065] The external leakage type water inlet valve (the valve is an outer valve body 1 provided with a leakage mechanism 7 for leakage) opens the leakage mechanism 7, which requires the driving part 715 to drive the contraction part to contract, and the connecting part 713 on the contraction part drives the leakage valve 711 to slide, so that the leakage valve 711 completely leaves the leakage port 716.

[0066] The beneficial effects of this technical solution are as follows:

[0067] The present invention provides a pressure-relief inlet valve for large hydraulic turbines. This valve is pressure-resistant and suitable for all types of hydraulic turbines, particularly those with ultra-high heads of 500 m and above. The inlet valve utilizes a direct current internal control structure, resulting in a favorable flow pattern and bidirectional flow. Its strong regulating capability allows for dynamic water opening and closing.

[0068] 2. The present invention provides a discharge and pressure-regulating water inlet valve for a large hydraulic turbine. As the main valve of a conventional hydraulic turbine, the valve can have a full-time self-closing tendency. In the event of failure of the oil pressure device, the main valve can have a self-closing tendency and close slowly to ensure the safety of the power station.

[0069] 3. The present invention provides a discharge and pressure regulating water inlet valve for a large turbine. The valve can provide flow to the turbine with a small opening, low flow, and for a long time, and can achieve the functional replacement of eliminating the bypass pipeline.

[0070] 4. The present invention provides a discharge and pressure-regulating water inlet valve for a large turbine. By adjusting the opening between the needle valve core and the valve, it can complete the basic opening and closing functions of the turbine water inlet valve. At the same time, through the adjustment and coordination of the valve, it can achieve precise control of the flow rate. The water inlet flow rate can be adjusted accordingly according to different working conditions, and the function of the turbine water guide mechanism can be replaced.

[0071] Fifth, the present invention provides a large-scale hydraulic turbine inlet valve with a pressure-relief valve. The main valve, pressure-relief valve 711, and piping are integrated into a single structure. The pressure-relief piping can be internally or side-mounted. During an emergency or shutdown, the pressure-relief piping opens, ensuring that the unit meets regulation requirements, resulting in significant economic benefits.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A discharge and pressure regulating water inlet valve for a large hydraulic turbine, characterized by: It comprises an outer valve body (1) and an inner valve body (2), wherein the outer valve body (1) is provided with a water inlet (3) and a water outlet (4) at both ends respectively, and the inner valve body (2) is connected to the outer valve body (1) via a guide vane (5), and a main valve core (6) is provided in a sliding manner at the end of the inner valve body (2) close to the water outlet (4), and the main valve core (6) is used to block the water outlet (4) and adjust the water output, and the main valve core (6) is provided with a discharge mechanism (7) for discharge; The upper end of the inner valve body (2) is provided with a main valve core sliding groove (8), the main valve core (6) is slidably arranged in the main valve core sliding groove (8), the main valve core (6) is connected to the first-stage piston assembly (9), and the first-stage piston assembly (9) is slidably arranged in the main valve core (6); The first-stage piston assembly (9) comprises a first-stage piston rod (91), one end of the first-stage piston rod (91) is connected to a first-stage piston (92), the other end of the first-stage piston rod (91) is connected to the main valve core (6), the first-stage piston (92) is located in a first-stage operating oil chamber (93) in the main valve core (6), and operating oil pipes (12) are provided on the first-stage operating oil chambers (93) on both sides of the first-stage piston (92); The discharge mechanism (7) includes a secondary valve core (721) and a secondary piston assembly (722), wherein the secondary valve core (721) is connected to the secondary piston assembly (722), a reflux chamber (728) is provided between the secondary valve core (721) and the secondary piston assembly (722), the reflux chamber (728) is connected to a reflux pipe (727), and the reflux pipe (727) passes through the inner valve body (2) and the outer valve body (1), and the secondary piston assembly (722) is slidably provided in the primary piston rod (91); A reflux port (723) is provided in the middle of the main valve core (6), the reflux port (723) is communicated with the reflux chamber (728), a secondary valve core (721) is slidably provided in the reflux port (723), and the secondary valve core (721) is used to block the reflux port (723) and adjust the reflux amount; The secondary piston assembly (722) includes a secondary piston rod (724), the secondary piston rod (724) is connected to the secondary valve core (721), and a secondary piston (725) is sleeved on the secondary piston rod (724). The secondary piston (725) is located in a secondary operating oil chamber (726) in the primary piston rod (91), and operating oil pipes (12) are provided on the secondary operating oil chambers (726) on both sides of the secondary piston (725).

2. A discharge and pressure regulating water inlet valve for a large hydraulic turbine according to claim 1, characterized in that: A balancing sleeve (10) is also provided on the primary piston rod (91).

3. A large-scale hydraulic turbine discharge pressure regulating inlet valve according to claim 2, characterized in that: The inner valve body (2) is provided with an arc-shaped tail cover (11) at the end close to the water inlet (3).

4. A method for using a discharge and pressure regulating inlet valve for a large hydraulic turbine according to any one of claims 1 to 3, characterized in that: The following usage statuses are included: Valve fully closed: the discharge mechanism (7) is closed, and the first-stage piston assembly (9) drives the main valve core to move until the main valve body completely blocks the water outlet (4); The valve is partially open: the discharge mechanism (7) is closed, and the first-stage piston assembly (9) drives the main valve core to move so that there is a certain gap between the main valve body and the water outlet (4); Valve fully open: the discharge mechanism (7) is closed, and the first-stage piston assembly (9) drives the main valve core to move until the main valve body stops moving; The valve is fully open for normal operation. When the unit is shut down in an emergency, the first-stage piston assembly (9) drives the main valve core to move until the main valve body stops moving, opening the discharge mechanism (7).

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