A high, medium and low voltage bypass control system

Abstract

This utility model discloses a high, medium, and low pressure bypass control system, relating to the technical field of bypass control systems. It includes: a split feedback unit for real-time valve position detection and conversion into electrical signals; a control box installed away from high-temperature pipelines, integrating pneumatic control components; an air source processing module including a filter and pressure reducing valve, with its input end connected to a compressed air main pipe and its output end providing purified and pressure-regulated air; a positioning and amplification module including a split positioner and a speed-increasing relay, the split positioner receiving remote control commands and signals from the split feedback unit, and driving the cylinder actuation through the speed-increasing relay; a safety function module integrating a quick-opening solenoid valve, a quick-closing solenoid valve, a pneumatic control valve, and a locking valve to achieve quick-opening / quick-closing and air-out position retention functions; and an energy storage device connected to the output end of the air source processing module via a one-way valve. This utility model integrates pneumatic speed increase, air-out self-locking, and energy storage emergency protection, enabling the bypass valve control to possess high-temperature resistance, millisecond-level response, and intrinsic safety characteristics.

Description

Technical Field

[0001] This utility model relates to the field of bypass control system technology, and in particular to a high, medium and low voltage bypass control system. Background Technology

[0002] The turbine bypass control system is an integral part of the modern unit's thermal system. Its function is to allow excess steam to bypass the turbine and be desuperheated and depressurized before being directly introduced into the condenser when the boiler and turbine operating conditions are mismatched (i.e., the boiler produces more steam than the turbine requires). Furthermore, some bypasses also desuperheat and depressurize the boiler's main steam before introducing it directly into the reheater to protect its safety. These functions of the bypass system are essential during unit startup, load reduction, or load shedding.

[0003] When the unit is cold-started, the steam output from the boiler is greater than the steam required by the turbine during turbine startup, speed-up, or initial load operation. In this case, the bypass system can be used for startup venting. This allows the boiler to independently establish steam temperature and pressure compatible with the turbine, ensuring a smooth integrated startup and shortening the unit's startup time, while also extending the turbine's service life. Compared to venting to the atmosphere, it recovers the working fluid and eliminates noise pollution. When the unit rapidly reduces load, the turbine needs to quickly close the main steam valve, while the boiler can only reduce load slowly, meaning the boiler cannot keep up. In this situation, the bypass system acts as a pressure relief valve. The presence of the bypass system allows the boiler to continue operating independently of the turbine. The greater and faster the load reduction, the more advantageous it becomes. In the event of a load shedding incident, the bypass system allows the boiler to operate within the allowable evaporation rate, diverting excess steam to the condenser. This gives operators time to determine the cause of the load shedding and decide whether the boiler load should be further reduced or maintained so that the turbine generator unit can be quickly reconnected to the grid.

[0004] To enable the bypass system to respond quickly to the operating requirements of the boiler or steam turbine under various operating conditions, a complete bypass control device needs to be designed.

[0005] Traditional steam turbine high, medium, and low pressure bypass valve control devices mostly use electric actuators or integrated pneumatic controls, which have significant drawbacks:

[0006] Poor adaptability to high-temperature environments: Actuators and positioners are installed directly near the high-temperature valve body, which leads to aging of seals, damage to electronic components, and a high failure rate.

[0007] Insufficient response speed: The electric actuator has a long full-stroke action time to drive the valve, which cannot meet the rapid opening and closing requirements of the unit under conditions such as load shedding;

[0008] Risk of gas supply interruption and loss of control: There is a lack of emergency mechanism when the gas supply is interrupted, and valve position drift may cause reheater overheating or boiler overpressure;

[0009] High maintenance costs: High-temperature environments lead to frequent component replacements, and modifications require downtime for construction, affecting unit availability.

[0010] While existing technologies attempt to adopt a split design, they have not solved the problems of integrated optimization and safety redundancy of the pneumatic control module, making it difficult to balance reliability, speed, and anti-interference capabilities. Utility Model Content

[0011] The purpose of this utility model is to provide a high, medium and low pressure bypass control system that is easy to install, has a low failure rate, operates quickly, and has power failure and signal failure protection as well as fast opening and fast closing functions. It can quickly respond to the operating requirements of boilers or steam turbines under various operating conditions, so as to solve the problems existing in the prior art.

[0012] To achieve the above objectives, this utility model provides the following solution:

[0013] A high, medium, and low voltage bypass control system includes:

[0014] The split feedback unit RS is installed on the valve stem of the pneumatic actuator to detect the valve position in real time and convert it into an electrical signal;

[0015] The control box is installed independently away from high-temperature pipelines and integrates pneumatic control components.

[0016] The air source processing module includes a filter pressure reducing valve, with the input end connected to the compressed air main pipe and the output end providing purified and pressure-regulated air source;

[0017] The positioning amplification module includes a split positioner and speed-increasing relays DV1 and DV2. The split positioner receives remote control commands and split feedback unit signals, and drives the cylinder to move through the speed-increasing relays.

[0018] The safety function module integrates the quick-opening solenoid valve EV2, the quick-closing solenoid valve EV1, the pneumatic control valves D1-D4, and the locking valves D5 and D6 to realize quick-opening / quick-closing and air-cut-off position-holding functions.

[0019] The energy storage device is connected to the output of the gas source processing module via a one-way valve to provide an emergency gas source in the event of a gas outage.

[0020] In one exemplary embodiment, the safety function module includes a gas supply interruption and position maintenance unit:

[0021] The SIG ports of locking valves D5 and D6 are connected to the compressed air main pipe to monitor the air source pressure in real time.

[0022] When the air supply is lost, the locking valve automatically cuts off the passage between the IN port and the OUT port, so that the cylinder pressure remains at the current state.

[0023] In an exemplary embodiment, the energy storage device is connected to the cylinder via pneumatic control valves D1 and D4:

[0024] When the quick open / quick close command is triggered, the energy storage gas source directly drives the cylinder through the pneumatic control valve D1 or D4 to achieve rapid opening / closing of the valve.

[0025] In an exemplary embodiment, the positioning amplification module includes speed-increasing relays DV1 and DV2:

[0026] The SIG signal port of the speed increase relay is connected to the output terminals OUT1 and OUT2 of the split positioner, and the SUP port is connected to the purified air source.

[0027] The OUT output port directly drives the cylinder to open / close the air inlet, amplifying the flow rate to increase the valve's operating speed.

[0028] In an exemplary embodiment, the pneumatic path structure of the quick-open / quick-close function is as follows:

[0029] The quick-closing solenoid valve EV1 controls the switching of the pathways of pneumatic control valves D1 and D2:

[0030] Under normal conditions, the fast-closing solenoid valve EV1 is de-energized, and the pneumatic control valves D1 and D2 are connected to the speed-increasing relays DV1 and DV2 and the cylinder.

[0031] When triggered, the fast-closing solenoid valve EV1 is energized, the pneumatic control valve D1 switches to supply air to the energy storage device, and the pneumatic control valve D2 switches to exhaust.

[0032] The control logic of the quick-opening solenoid valve EV2 is symmetrical with that of the quick-closing solenoid valve EV1.

[0033] In an exemplary embodiment, the quick-closing solenoid valve EV1 and the quick-opening solenoid valve EV2 are two-position three-way direct-acting types:

[0034] The zero-position state is AR connectivity, and it switches to AP connectivity during action.

[0035] The coil is energized only at the moment of triggering to avoid damage from prolonged energization.

[0036] In one exemplary embodiment, the split-type positioner is an ABB-EDP300 model:

[0037] It has power failure / signal failure retention function, and the output terminals OUT1 and OUT2 are connected to the SIG port of the speed increase relay.

[0038] In an exemplary embodiment, the components within the control box are arranged as follows:

[0039] The output of the gas source processing module is connected in sequence to the SUP port of speed increase relays DV1 and DV2, the check valve, and the energy storage device;

[0040] The R port of the quick-opening solenoid valve EV2 and the quick-closing solenoid valve EV1 is connected to the output pipeline of the filter pressure reducing valve.

[0041] In an exemplary embodiment, the split feedback unit RS is connected to the valve stem via a mechanical linkage:

[0042] A linear motion converter is used to convert valve stem displacement into an electrical signal and transmit it to a split-type positioner.

[0043] In an exemplary embodiment, the device is suitable for a steam turbine high-pressure bypass valve HP, a medium-pressure bypass valve (ZP), and a low-pressure bypass valve LP:

[0044] The control box is configured with the following parameters: air source pressure 0.35-0.45 MPa, and valve full stroke action time ≤ 5 seconds.

[0045] The present invention achieves the following technical advantages over the prior art:

[0046] 1. By adopting a split feedback unit, which is independently installed on the valve stem of the pneumatic actuator, the valve position is detected in real time and converted into an electrical signal. The pneumatic control components are integrated in the control box, which is independently installed away from the high-temperature pipeline to avoid thermal aging of the seals and damage to electronic components. At the same time, the modular deployment of the pre-installed and debugged control box supports live modification, which can significantly reduce downtime.

[0047] 2. By using speed-increasing relays (DV1 / DV2) to amplify the flow and coordinate with the energy storage device for emergency gas supply, the demand for quick opening / closing during load shedding can be met, and the action speed can be increased to ≤5 seconds.

[0048] 3. By using locking valves (D5 / D6) to monitor the main pipe pressure in real time and automatically cut off the gas circuit, valve position drift is completely eliminated, achieving zero-risk position maintenance during gas outages. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 A schematic diagram of the high, medium and low voltage bypass control system disclosed in a specific embodiment of this utility model;

[0051] Figure 2for Figure 1 Pneumatic control schematic diagram of the medium-fast closing solenoid valve EV1 and the fast opening solenoid valve EV2;

[0052] Figure 3 for Figure 1 Pneumatic control principle diagram of pneumatic control valves D1, D2, D3, and D4. Detailed Implementation

[0053] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0054] The purpose of this utility model is to provide a high, medium and low pressure bypass control system that is easy to install, has a low failure rate, operates quickly, and has power failure and signal failure protection as well as fast opening and fast closing functions, which can quickly respond to the action requirements of boilers or steam turbines under various operating conditions.

[0055] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Please refer to Figures 1 to 3 This embodiment provides a high, medium, and low pressure bypass control system, which adopts a split design. The core structure consists of a control box (500×600×200mm) and a split feedback unit RS. The size of the control box can be adjusted according to the on-site installation location. The split feedback unit RS is installed on the valve stem of the pneumatic actuator to detect the valve position in real time and convert it into an electrical signal. The control box is installed independently away from high-temperature pipelines and integrates pneumatic control components: an air source processing module, a positioning amplification module, and a safety function module. The air source processing module includes a filter pressure reducing valve, with its input end connected to the compressed air main pipe and its output end providing purified and pressure-regulating air. The positioning amplification module includes a split positioner and speed-increasing relays DV1 and DV2. The split positioner receives remote control commands and signals from the split feedback unit, and drives the cylinder to move through the speed-increasing relays. The safety function module integrates a quick-opening solenoid valve EV2, a quick-closing solenoid valve EV1, pneumatic control valves D1-D4, and locking valves D5 and D6 to achieve quick-opening / quick-closing and air-cut-off position-holding functions. It also includes an energy storage device, which is connected to the output of the gas source processing module via a one-way valve to provide an emergency gas source in the event of a gas outage.

[0057] The positioning amplification module includes a split-type positioner and two speed-increasing relays, DV1 and DV2. The split feedback unit is mounted on the high / low pressure bypass pneumatic actuator and connected to the valve stem via a positioner bracket. During valve opening and closing, the valve stem drives the shaft of the split feedback unit to rotate, converting the valve's position information into an electrical signal. This electrical signal is transmitted to the split-type positioner via a communication cable, which can display the valve's actual position in real time and send remote position signals to control systems such as DCS. Furthermore, the split-type positioner can receive 4-20mA control commands from a remote location. Inside the split-type positioner, the command signal and feedback signal are compared in a closed loop, resulting in an output signal controlling the valve's movement. This control signal is the control air source, connected to the SIG signal ports of speed-increasing relays DV1 and DV2 via the split-type positioner's air source ports OUT1 and OUT2, respectively, to control the output air supply of speed-increasing relays DV1 and DV2. In other words, the air supply ports OUT1 and OUT2 of the split positioner will increase or decrease the air supply according to the deviation between the actual valve position and the command, thereby proportionally increasing or decreasing the output air supply of the speed-increasing relays DV1 and DV2. The maximum air supply of speed-increasing relays DV1 and DV2 is limited by their input air supply. The output air supply of speed-increasing relays DV1 and DV2 serves as the driving air source for the cylinders of the high, medium, and low pressure bypass pneumatic actuators. The output port of speed-increasing relay DV1 is connected to the cylinder's valve-closing inlet. When this path is supplied, compressed air enters the cylinder through the valve-closing inlet, pushing the cylinder to move in the closing direction until the valve is completely closed. The output port of speed-increasing relay DV2 is connected to the cylinder's valve-opening inlet. When this path is supplied, compressed air enters the cylinder through the valve-opening inlet, pushing the cylinder to move in the opening direction until the valve is completely open.

[0058] The safety function module is further divided into the quick-close function module, the quick-close function module, and the position-keeping function module.

[0059] The quick-closing function module includes one quick-closing solenoid valve EV1, one pneumatic control valve D1, and one pneumatic control valve D2. Its main function is to respond to remote quick-closing commands or manual operation by controlling the on / off state of the quick-closing solenoid valve EV1, thereby switching the air paths of pneumatic control valves D1 and D2. This process involves rapid air intake on the cylinder's valve-closing side and rapid air exhaust on the valve-opening side to drive the high, medium, and low bypass valves to close quickly. Specifically, the quick-closing solenoid valve EV1 is a two-position, three-way, direct-acting solenoid valve, with its zero position being normally open. In the unenergized state, port A is connected to port R; after energization, port A is connected to port P. Remote commands control the on / off state of the quick-closing solenoid valve EV1 to control whether air enters the pneumatic control ports of pneumatic control valves D1 and D2. When air enters through the pneumatic control port, ports 1 and 2 of pneumatic control valves D1 and D2 are connected; conversely, when air does not enter through the pneumatic control port, the air paths of pneumatic control valves D1 and D2 are switched, connecting ports 2 and 3. Port 3 of pneumatic control valve D2 is not connected to any device and is used for rapid exhaust. By controlling the on / off state of the quick-closing solenoid valve EV1, the switching of the air paths of pneumatic control valves D1 and D2 is controlled, thereby connecting or disconnecting the air source output by the speed-increasing relays DV1 and DV2 of the positioning amplification function module.

[0060] For example, when the quick-closing solenoid valve EV1 is not energized, compressed air enters from the air supply main pipe through the R port of the quick-closing solenoid valve EV1 and exits from the A port. It is then supplied to the air control ports of the pneumatic control valves D1 and D2 through the connected air source pipeline, so that ports 1 and 2 of the pneumatic control valves D1 and D2 are connected, thereby realizing the closing and opening of the valves.

[0061] When the quick-closing solenoid valve EV1 is energized, to achieve rapid closure of the high, medium, and low bypass valves, the air path of the quick-closing solenoid valve EV1 is switched, causing port R to disconnect from port A and port A to connect with port P. At this time, compressed air cannot enter through port R of the quick-closing solenoid valve EV1, and the air source output from port A is discharged to the atmosphere through ports A and P of the quick-closing solenoid valve EV1. This causes the air source for the air control ports of pneumatic control valves D1 and D2 to disappear, prompting pneumatic control valves D1 and D2 to switch their air paths, changing from the original connection of ports 1 and 2 to the connection of ports 2 and 3. At this time, port 3 of pneumatic control valve D2 acts as an exhaust port, not connected to the air source pipeline, and is directly discharged to the atmosphere, releasing the air supply pressure of the lower cylinder valve opening. Meanwhile, ports 2 and 3 of the pneumatic control valve D1 are connected, and port 3 of the pneumatic control valve D1 is connected to the output air source pipeline of the energy storage device. The compressed air in the energy storage device enters the valve closing cylinder of the pneumatic actuator cylinder of the high, medium and low pressure bypass valve through ports 3 and 2 of the pneumatic control valve D1. Through the action of compressed air, the high and low pressure bypass valves are quickly closed.

[0062] The quick-opening function module includes one quick-opening solenoid valve EV2, one pneumatic control valve D3, and one pneumatic control valve D4. Its main function is to switch the air path of the pneumatic control valves D3 and D4 by means of a quick-opening command given remotely or by manually operating the quick-opening solenoid valve EV2, so as to achieve rapid air intake on the cylinder valve-opening side and rapid air exhaust on the cylinder valve-closing side, thereby driving the high and low pressure bypass valves to open quickly.

[0063] The specific operation is as follows: The quick-opening solenoid valve EV2 is a two-position, three-way, direct-acting solenoid valve. In the zero position, it is normally open, meaning that when the EV2 coil is not energized, port A and port R are connected; when the EV2 coil is energized, the air path switches, and port A and port P are connected. Remote commands control whether the EV2 coil is energized, thereby determining whether air is supplied to the A port outlet via the R port inlet. In other words, the EV2 solenoid valve controls whether air enters the air control ports D3 and D4. When air enters the air control ports, ports 1 and 2 of D3 and D4 are connected; when air does not enter, ports 2 and 3 of D3 and D4 are connected. Therefore, controlling the energization of the EV2 coil controls the switching of the air path between D3 and D4. By controlling the air path switching of D3 and D4, the output air source of the speed-increasing relays DV1 and DV2 of the positioning amplification function module can be connected or disconnected.

[0064] For example, when the coil of the quick-opening solenoid valve EV2 is not energized, compressed air from the air supply main pipe enters through port R of the quick-opening solenoid valve EV2 and exits from port A. It supplies air to the air control ports of the pneumatic control valves D3 and D4 through the connected air source pipe. At this time, ports 2 and 1 of the pneumatic control valves D3 and D4 are connected. The output air source from the speed-increasing relays DV1 and DV2 of the positioning amplification function module enters the valve-closing side and valve-opening side of the cylinder through ports 1 and 2 of the connected pneumatic control valves D1 and D2, respectively, thereby realizing the valve closing and opening.

[0065] When the coil of the quick-opening solenoid valve EV2 is energized, the high, medium, and low pressure bypass valves need to be opened quickly. At this time, the air path of the quick-opening solenoid valve EV2 is switched, the R terminal is disconnected from the A terminal, and the A terminal is connected to the P terminal. Compressed air from the air supply main pipe cannot enter through the R port of the quick-opening solenoid valve EV2 and exit from the A port. At this time, the A port is connected to the P port, that is, the air source of the air control valves D3 and D4 connected to the A port is discharged to the atmosphere through the A and P ports of the quick-opening solenoid valve EV2, causing the air source of the air control valves D3 and D4 to disappear, causing the air control valves D3 and D4 to switch their air paths, changing from the original connection of ports 1 and 2 to the connection of ports 2 and 3. At this time, the 2 and 3 ports of the air control valve D3 are connected to the atmosphere as exhaust ports, not connected to the air source pipeline, and are directly discharged to the atmosphere, releasing the air supply pressure of the cylinder upper valve closing valve. At the same time, ports 2 and 3 of the pneumatic control valve D4 are connected, and port 3 of the pneumatic control valve D4 is connected to the output air source pipeline of the energy storage device. The compressed air in the energy storage device enters the lower cylinder of the high, medium and low pressure bypass valve through ports 2 and 3 of the pneumatic control valve D4. Through the action of the compressed air, the high and low pressure bypass valves are opened quickly.

[0066] The position-holding module consists of two components: locking valves D5 and D6, typically installed at the end of the air supply line for opening or closing the cylinder, near the cylinder side. The function of this module is to prevent the pneumatic actuator from losing compressed air supply, such as due to leaks in the air supply line or damage to the filter / pressure reducing valve. If the high, medium, and low pressure bypass valves are in the intermediate position, the high and low pressure valves may experience position fluctuations due to the flow of the high-pressure medium, or even accidental opening or closing. To ensure that the valve is locked and the cylinder maintains pressure in the event of a failure in the pneumatic actuator's air supply or line, thus causing an accident in the pneumatic control device, until the air supply or line is restored, this position-holding module is designed to maintain the valve's current opening position during periods of compressed air power loss.

[0067] Locking valves D5 and D6 are generally available in single-acting and double-acting types, meaning they control the connection between the inlet and outlet ports via a signal air source. Single-acting locking valves typically have three ports: a SIG port connected to the signal air source, an IN port for inlet air, and an OUT port for outlet air. When safety signal air pressure enters the SIG port, it connects the IN port and the OUT port; when the safety signal air pressure disappears, the IN port and the OUT port disconnect. At this time, the safety signal air pressure is the same as the compressed air main supply pressure. When the compressed air main supply pressure disappears, it is considered that the compressed air source has disappeared, and this is determined as a "gas cut-off". In other words, the locking valve signal air source SIG port monitors the compressed air pressure of the main pipe in real time. When the compressed air pressure of the main pipe disappears, it will quickly cut off the inlet port IN and the outlet port OUT, so that the pressure of the pipeline and cylinder connected after the outlet port OUT can be maintained, and the valve will maintain its current position until the compressed air pressure of the main pipe is restored. When the safety signal air pressure enters the SIG port, the inlet port IN and the outlet port OUT will be reconnected, so that the intake or exhaust operation of the upper and lower cylinders can be normally realized, and the opening or closing control of the pneumatic valve can be achieved.

[0068] The pneumatic actuator's pneumatic control instrument components, such as split-type positioners, speed-increasing relays, solenoid valves, and locking valves, have extremely high requirements for compressed air quality. Typically, compressed air contains impurities such as moisture and oil, which can lead to blockages in various pneumatic control instrument components, decreased regulation quality, and inability to switch pneumatic circuits, such as solenoid valves. In this embodiment, a filter pressure reducing valve with water, oil, and pressure regulating functions is designed and installed. This prevents water and dust from entering the pneumatic instrument components and maintains a stable output pressure even if the supply air pressure changes. This filter pressure reducing valve is installed at the front end of the compressed air source main pipe, and its output end is connected to the SUP air supply ports of the split-type positioner IN1, speed-increasing relays DV1 and DV2, and the inlet IN of the accumulator, among other pneumatic instrument components. Depending on the selected split-type positioner, the output compressed air pressure is adjusted, generally set between 0.35 MPa and 0.45 MPa.

[0069] This embodiment features an energy accumulator, designed to maintain the compressed air supply to the pneumatic actuator in the event of an interruption in the compressed air main supply, ensuring the actuator can move the high, medium, and low pressure bypass valves to a safe position. To prevent backflow of compressed air in the accumulator and subsequent pressure drop after the compressed air supply is interrupted, a one-way valve is installed on the air supply line between the filter pressure reducing valve output and the accumulator. This one-way valve is open from the filter pressure reducing valve output to the accumulator inlet, and closed from the accumulator to the filter pressure reducing valve. Furthermore, this one-way valve is located after the SUP air supply port of the speed-increasing relays DV1 and DV2 from the filter pressure reducing valve output, and before the R-port of the quick-closing solenoid valves EV1 and EV2. The air supply line connected to the output port of the filter pressure reducing valve is first connected to the SUP air supply port of the speed increase relay DV1, then to the SUP air supply port of the speed increase relay DV2, and then to the air inlet of the one-way valve DX. The air outlet of the one-way valve DX is connected to the air inlet of the energy storage device.

[0070] The working principle of the pneumatic control circuit in this embodiment is as follows: The compressed air source pipe obtained from the outlet main pipe of the field air compressor is connected to the inlet IN port of the filter pressure reducing valve. The filter pressure reducing valve has water filtration, oil filtration, and pressure regulation functions, and its output pressure needs to be adjusted to within the range of 0.35Mpa to 0.45Mpa. The air source output by the filter pressure reducing valve is connected via the output OUT port to the inlet IN port of the split positioner of the positioning amplification function module, the inlet SUP port of the speed increase relay DV1, the inlet SUP port of the speed increase relay DV2, the inlet R port of the quick-closing solenoid valve EV1 and the quick-opening solenoid valve EV2, and the inlet IN port of the one-way valve DX of the auxiliary function module.

[0071] When air is supplied to the IN port of the split-type positioner in the positioning amplification function module, the split-type positioner completes valve position setting and then performs automatic control (manual control is also possible). It receives control commands from the remote DCS and compares them with the valve position feedback signal transmitted back by the split feedback unit RS, thereby automatically controlling the air supply output of the split-type positioner. When the valve position fed back by the split feedback unit RS is greater than the valve position commanded by the DCS, air is supplied to port OUT1 of the split-type positioner to close the pneumatic actuator valve; similarly, when the valve position fed back by the split feedback unit RS is less than the valve position commanded by the DCS, air is supplied to port OUT2 of the split-type positioner to open the pneumatic actuator valve.

[0072] The output ports OU1 and OUT2 of the split-type positioner are connected to the signal pressure supply ports IN of the speed-increasing relays DV1 and DV2, respectively, to drive the speed-increasing relays DV1 and DV2. When the split-type positioner determines that the actual valve position is greater than the valve position given by the control command, it needs to drive the valve to close to the specified position. At this time, the air source output port OUT1 of the split-type positioner outputs control air to the signal pressure supply port IN of the speed-increasing relay DV1, connecting the inlet port SUP of the speed-increasing relay DV1 with the output port OUT. Furthermore, as the air source pressure at the air source output port OUT1 of the split-type positioner increases, the pressure at the output port OUT of the speed-increasing relay DV1 approaches the pressure at the inlet port SUP, and the output pressure and working fluid flow rate increase accordingly until the valve moves to the valve position given by the split-type positioner. When there is no more air source output at the air source output port OUT1 of the split-type positioner, the inlet port SUP of the speed-increasing relay DV1 disconnects from the output port OUT, and the valve stops moving.

[0073] Similarly, when the split-type positioner determines that the actual valve position is less than the valve position given by the control command, it needs to drive the valve to open to the specified position. At this time, the air source output port OUT2 of the split-type positioner outputs control air to the signal pressure supply port IN of the speed-increasing relay DV2, connecting the inlet SUP port and the output OUT port of the speed-increasing relay DV2. As the air source pressure at the air source output port OUT2 of the split-type positioner increases, the pressure at the output OUT port of the speed-increasing relay DV2 gets closer to the pressure at the inlet SUP port, and the output pressure and working fluid flow rate increase until the valve moves to the position given by the split-type positioner. When there is no more air source output at the air source output port OUT2 of the split-type positioner, the inlet SUP port and the output OUT port of the speed-increasing relay DV2 are disconnected, and the valve stops moving.

[0074] The air supply output from the OUT ports of the speed-increasing relays DV1 and DV2 in the positioning amplification function module enters the upper and lower cylinders of the cylinder through air supply pipelines, respectively, to drive the high, medium, and low pressure bypass pneumatic valves to move in the closing and opening directions. Compared with directly using a positioner to drive the valve in the opening and closing direction, its main purpose is to increase the valve's operating speed.

[0075] The output OUT ports of the speed-increasing relays DV1 and DV2 of the positioning amplification function module are connected to the input 1 ports of the pneumatic control valves D1 and D2 of the fast-closing function module, respectively. The output 2 ports of the pneumatic control valves D1 and D2 are connected to the input 1 ports of the pneumatic control valves D3 and D4 of the fast-opening function module, respectively. Furthermore, the exhaust port 3 of the pneumatic control valve D1 of the fast-closing function module is connected to the outlet OUT port of the accumulator via a compressed air pipeline, while the exhaust port 3 of the pneumatic control valve D2 of the fast-closing function module exhausts to the atmosphere. Moreover, the pneumatic control ports of the pneumatic control valves D1 and D2 of the fast-closing function module are connected to the output A port of the fast-closing solenoid valve EV1, and the input R port of the fast-closing solenoid valve EV1 is connected to the compressed air pipeline from the output OUT port of the filter pressure reducing valve to the input IN port of the accumulator, with the connection point located after the output OUT port of the one-way valve DX.

[0076] The quick-closing function module includes one quick-closing solenoid valve EV1, one pneumatic control valve D1, and one pneumatic control valve D2. Its main function is to control the air circuit switching of pneumatic control valves D1 and D2 by remotely issuing a quick-closing command or manually operating the quick-closing solenoid valve EV1. This achieves rapid air intake for the cylinder on the valve-closing side and rapid air exhaust for the cylinder on the valve-opening side, thereby quickly closing the high, medium, and low bypass valves. The specific operation is as follows: The quick-closing solenoid valve EV1 is a two-position, three-way, direct-acting solenoid valve. In the zero position, it is normally open; that is, when the coil of the quick-closing solenoid valve EV1 is not energized, terminals A and R are connected; when the coil of the quick-closing solenoid valve EV1 is energized, terminals A and P are connected. The remote command controls whether air is supplied to the air outlet at terminal A through the air inlet at terminal R by controlling whether the coil of the quick-closing solenoid valve EV1 is energized. In other words, the quick-closing solenoid valve EV1 controls whether air enters the air control ports of pneumatic control valves D1 and D2. When air enters the air control ports, ports 1 and 2 of pneumatic control valves D1 and D2 are connected; when air does not enter the air control ports, the air paths of pneumatic control valves D1 and D2 are switched, connecting ports 2 and 3 of pneumatic control valves D1 and D2. Port 3 of pneumatic control valve D2 is not connected to any equipment and is used for rapid exhaust to the atmosphere. In other words, by controlling whether the coil of the quick-closing solenoid valve EV1 is energized, the goal of controlling the switching of the air paths of pneumatic control valves D1 and D2 is achieved, thus connecting or disconnecting the output air source of the speed-increasing relays DV1 and DV2 of the positioning amplification function module. For example, when the coil of the quick-closing solenoid valve EV1 is not energized, compressed air from the air supply main pipe enters through port R of the quick-closing solenoid valve EV1 and exits from port A. This air is then supplied to the pneumatic control ports of pneumatic control valves D1 and D2 through the connected air source pipeline, making ports 1 and 2 of pneumatic control valves D1 and D2 conductive. The valve closing and opening air sources output from the speed-increasing relays DV1 and DV2 of the positioning amplification function module are output through ports 1 and 2 of pneumatic control valves D1 and D2, respectively, for closing and opening the valves. When the coil of the quick-closing solenoid valve EV1 is energized, to achieve the rapid closing function of the high, medium, and low voltage bypass valves, the air path of the quick-closing solenoid valve EV1 is switched. Port R is disconnected from port A, and port A is conductive to port P. At this time, compressed air from the air supply main pipe cannot enter through port R of the quick-closing solenoid valve EV1 and exit from port A.At this time, ports A and P are connected, meaning the air supply from the pneumatic control ports of pneumatic control valves D1 and D2, which are connected to port A, is discharged to the atmosphere through ports A and P of the quick-closing solenoid valve EV1. This causes the air supply from pneumatic control valves D1 and D2 to disappear, prompting them to switch their air paths. Pneumatic control valves D1 and D2, which were originally connected through ports 1 and 2, are now connected through ports 2 and 3. At this time, port 3 of pneumatic control valve D2 acts as an exhaust port, not connected to the air supply line, and is directly discharged to the atmosphere, releasing the air supply pressure for opening the lower cylinder valve. Simultaneously, ports 2 and 3 of pneumatic control valve D1 are connected, and port 3 of pneumatic control valve D1 is connected to the output air supply line of the accumulator. The compressed air in the accumulator enters the upper cylinder of the high, medium, and low pressure bypass valve pneumatic actuator through ports 3 and 2 of pneumatic control valve D1. Through the action of the compressed air, the high and low pressure bypass valves are quickly closed.

[0077] The quick-opening solenoid valve EV2 is a two-position, three-way, direct-acting solenoid valve, with its zero position being normally open. This means that when the coil of the quick-opening solenoid valve EV2 is not energized, ports A and R are connected; when the coil of the quick-opening solenoid valve EV2 is energized, the air path switches, and ports A and P are connected. Remote commands control whether the coil of the quick-opening solenoid valve EV2 is energized, thereby controlling whether air is supplied to the air outlet at port A via the air inlet at port R. In other words, the quick-opening solenoid valve EV2 controls whether air enters the air control ports of pneumatic control valves D1 and D2. When air enters the air control ports, ports 1 and 2 of pneumatic control valves D3 and D4 are connected; when air does not enter the air control ports, ports 2 and 3 of pneumatic control valves D3 and D4 are connected. In other words, by controlling whether the coil of the quick-opening solenoid valve EV2 is energized, the switching of the air path between pneumatic control valves D1 and D2 can be achieved. By controlling the air path switching of D3 and D4, the output air source of the speed-increasing relays DV1 and DV2 of the positioning amplification function module can be connected or disconnected.

[0078] For example, when the coil of the quick-opening solenoid valve EV2 is not energized, compressed air supplied by the air supply main pipe enters through port R of the quick-opening solenoid valve EV2, exits from port A, and then supplies air to the air control ports of pneumatic control valves D3 and D4 through the connected air source pipe. At this time, ports 2 and 1 of pneumatic control valves D3 and D4 are connected, and the valve-closing air source from the speed-increasing relays DV1 and DV2 of the positioning amplification function module is output through ports 1 and 2 of pneumatic control valves D3 and D4, supplying air to the valve-closing side and valve-opening side of the cylinder respectively, so as to realize the operation of closing and opening the valve.

[0079] When the coil of the quick-opening solenoid valve EV2 is energized, to achieve the rapid opening function of the high, medium, and low pressure bypass valves, the air path of the quick-opening solenoid valve EV2 is switched. Port R is disconnected from port A, and port A is connected to port P. At this time, compressed air from the main air supply line cannot enter through port R of the quick-opening solenoid valve EV2 and exit through port A. Port A is now connected to port P, meaning the air supply for the air control valves D3 and D4, which are connected to port A, is discharged to the atmosphere through ports A and P of the quick-opening solenoid valve EV2. This causes the air supply for air control valves D3 and D4 to disappear, prompting them to switch their air paths, changing from the original connection of ports 1 and 2 to the connection of ports 2 and 3. At this time, ports 2 and 3 of the air control valve D3 act as exhaust ports connected to the atmosphere, not connected to the air supply line, and are directly discharged to the atmosphere, releasing the air supply pressure of the cylinder upper valve. At the same time, ports 2 and 3 of the pneumatic control valve D4 are connected, and port 3 of the pneumatic control valve D4 is connected to the output air source pipeline of the energy storage device. The compressed air in the energy storage device enters the lower cylinder of the high, medium and low pressure bypass valve through ports 2 and 3 of the pneumatic control valve D4. With the help of the compressed air, the high, medium and low pressure bypass valves are opened quickly.

[0080] The output ports of the quick-opening function module's pneumatic control valves D3 and D4 are connected to the input (IN) ports of the position-holding function module's locking valves D5 and D6, respectively. Locking valves D5 and D6 typically have three air ports: a SIG port for connecting to the signal air source, an IN port for inlet air, and an OUT port for outlet air. The signal air source SIG port of locking valves D5 and D6 is connected to the OUT port of the accumulator. When the accumulator builds up compressed air pressure, compressed air is delivered to the signal air source SIG port of locking valves D5 and D6 via the air supply line, causing the IN port and OUT port of locking valves D5 and D6 to connect. At this time, the compressed air closing the valve at the OUT port of the quick-opening function module's pneumatic control valve D3 can be guided to the cylinder's valve-closing inlet port through the IN port and OUT port of locking valve D5. At the same time, the compressed air from the OUT port of the pneumatic control valve D4 of the quick-opening function module can be guided to the cylinder's inlet port through the IN port and OUT port of the locking valve D6.

[0081] When the safety signal air pressure of locking valves D5 and D6 disappears, it is considered that the compressed air source has disappeared, and this is determined as "air shortage". In other words, the locking valve signal air source SIG port monitors the compressed air pressure in the main pipe in real time. When the compressed air pressure in the main pipe disappears, the inlet (IN) port and outlet (OUT) port of locking valves D5 and D6 are quickly cut off, maintaining the pressure in the pipeline and cylinder connected after the outlet (OUT) port, and keeping the valves in their current position. The connection between the inlet (IN) port and outlet (OUT) port of locking valves D5 and D6 will only be restored when the compressed air pressure in the main pipe recovers and the safety signal air pressure enters the SIG port. This allows for normal intake or exhaust operations of the upper and lower cylinders, achieving the opening or closing of the pneumatic valves.

[0082] The OUT ports of the locking valves D5 and D6 of the position holding function module are connected to the valve closing inlet and valve opening inlet of the pneumatic actuator cylinder, respectively, and are used to close or open the high and low pressure bypass pneumatic actuator.

[0083] The high, medium, and low pressure bypass control system provided in this embodiment has two main features: First, it employs a split-type positioner, with the positioner control unit installed inside a control cabinet. This control cabinet is located away from high-temperature pipelines, and the split feedback unit is connected to the valve stem via a mechanical linkage to provide feedback on the actual valve position. Second, the positioner, locking valve, speed-increasing relay, pneumatic control valve, and solenoid valve designed and installed in this embodiment are all uniformly installed in a control box. This allows for reasonable arrangement and installation of all equipment based on equipment selection and control box size, and enables pre-installation, piping, and commissioning. If split-type modifications or new equipment are required, simply install the properly commissioned control box near the controlled cylinder, thus improving modification efficiency. For example, when a unit needs high and low pressure bypass modifications, the installation and commissioning time can be significantly shortened, facilitating mass production and commissioning, thereby reducing costs. The valve design in this embodiment features gas cut-off and position-maintaining functions as well as fast-opening and fast-closing functions, meeting the valve operation requirements of thermal power units under different operating conditions and maximizing the protection against reheater overheating and boiler overpressure. Based on this, various programmable control systems of thermal power units can be configured with protection logic. For example, when the temperature exceeds the limit after the high-temperature bypass valve, the DCS logic can be used to set a logic protection function for the high-temperature bypass valve to close quickly.

[0084] Any adaptive changes made according to actual needs are within the protection scope of this utility model.

[0085] It should be noted that, for those skilled in the art, it is obvious that this utility model is not limited to the details of the above exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this utility model is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high, medium and low pressure bypass control system, characterized by, include: The split feedback unit (RS) is installed on the valve stem of the pneumatic actuator to detect the valve position in real time and convert it into an electrical signal; The control box is installed independently away from high-temperature pipelines and integrates pneumatic control components. The air source processing module includes a filter and pressure reducing valve, with the input end connected to the compressed air main pipe and the output end providing purified and pressure-regulated air source; The positioning amplification module includes a split positioner and a speed-increasing relay (DV1, DV2). The split positioner receives remote control commands and split feedback unit signals, and drives the cylinder to move through the speed-increasing relay. The safety function module integrates a quick-opening solenoid valve (EV2), a quick-closing solenoid valve (EV1), pneumatic control valves (D1-D4), and locking valves (D5, D6) to achieve quick-opening / quick-closing and air-stop position retention functions. The energy storage device is connected to the output of the gas source processing module via a one-way valve to provide an emergency gas source in the event of a gas outage.

2. The high, intermediate and low pressure bypass control system of claim 1, wherein, The safety function module includes a gas cut-off and position-maintaining unit: The SIG port of the locking valve (D5, D6) is connected to the compressed air main pipe to monitor the air source pressure in real time; When the air supply is lost, the locking valve automatically cuts off the passage between the IN port and the OUT port, so that the cylinder pressure remains at the current state.

3. The high, intermediate and low pressure bypass control system of claim 1, wherein, The energy storage device is connected to the cylinder via pneumatic control valves (D1, D4): When the quick open / quick close command is triggered, the energy storage gas source directly drives the cylinder through the pneumatic control valve (D1 or D4) to realize the rapid opening / closing of the valve.

4. The high, intermediate and low pressure bypass control system of claim 1, wherein, The positioning amplification module includes speed-increasing relays (DV1, DV2): The SIG signal port of the speed increase relay is connected to the output terminal (OUT1, OUT2) of the split positioner, and the SUP port is connected to the purified air source; The output port (OUT) directly drives the cylinder to open / close the air inlet, amplifying the flow rate to increase the valve's operating speed.

5. The high, intermediate and low pressure bypass control system of claim 1, wherein, The pneumatic circuit structure for the quick-open / quick-close function is as follows: The quick-closing solenoid valve (EV1) controls the switching of the pneumatic control valves (D1, D2): In normal conditions, the fast-closing solenoid valve (EV1) is de-energized, and the pneumatic control valves (D1, D2) connect the speed-increasing relays (DV1, DV2) to the cylinder; When triggered, the fast-closing solenoid valve (EV1) is energized, the pneumatic control valve (D1) switches to supply air to the accumulator, and the pneumatic control valve (D2) switches to exhaust. The control logic of the quick-opening solenoid valve (EV2) is symmetrical to that of the quick-closing solenoid valve (EV1).

6. The high, intermediate and low pressure bypass control system of claim 5, wherein, The quick-closing solenoid valve (EV1) and quick-opening solenoid valve (EV2) are two-position three-way direct-acting types. The zero-position state is AR connectivity, and it switches to AP connectivity during action. The coil is energized only at the moment of triggering to avoid damage from prolonged energization.

7. The high, intermediate and low pressure bypass control system of claim 1, wherein, The split-type positioner is the ABB-EDP300 model. It has power failure / signal failure retention function, and the output terminals (OUT1, OUT2) are connected to the SIG port of the speed increase relay.

8. The high, intermediate and low pressure bypass control system of claim 1, wherein, The components inside the control box are arranged as follows: The output of the gas source processing module is connected in sequence to the SUP port of the speed increase relay (DV1, DV2), the one-way valve, and the energy storage device. The R port of the quick-opening solenoid valve (EV2) and the quick-closing solenoid valve (EV1) is connected to the output pipeline of the filter pressure reducing valve.

9. The high, intermediate and low pressure bypass control system of claim 1, wherein, The split feedback unit (RS) is connected to the valve stem via a mechanical linkage: A linear motion converter is used to convert valve stem displacement into an electrical signal and transmit it to a split-type positioner.

10. The high, medium and low pressure bypass control system according to any one of claims 1-9, characterized in that, The device is suitable for high pressure bypass valve (HP), medium pressure bypass valve (ZP) and low pressure bypass valve (LP) of steam turbine: The element parameter configuration in the control box is: air source pressure 0.35-0.45Mpa, valve full stroke action time ≤5 seconds.

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