A method and system of a pneumatic emergency shut-off valve with failure self-diagnosis and fault-tolerant control

Abstract

The present application belongs to the technical field of industrial process control and pneumatic safety cut-off, and discloses a method and system of a pneumatic emergency cut-off valve with failure self-diagnosis and fault-tolerant control, comprising: step 1, obtaining a detection signal item and a parameter group, and establishing a cut-off state transmission chain; step 2, determining a trigger source and a preferred pressure relief path; step 3, determining a pressure release amount, a valve rod closing stroke amount and a state node; step 4, determining a first failure link and a closing force margin; step 5, executing a fault-tolerant cut-off path and re-verifying; step 6, determining a pipeline process isolation state; and step 7, verifying state consistency, determining a final effective cut-off state and executing a reset interlock. The present application realizes valve failure self-diagnosis, effective medium isolation verification and safe reset interlocking.

Description

Technical Field

[0001] This invention belongs to the field of industrial process control and pneumatic safety shut-off technology, specifically relating to a pneumatic emergency shut-off valve method and system with failure self-diagnosis and fault-tolerant control. Background Technology

[0002] Pneumatic emergency shut-off valves are typically installed in gas, chemical media, and pressure pipelines. In the event of overheating, pressure loss, or emergency shutdown, they release gas from the pneumatic piston's working chamber, causing a return spring to actuate the valve stem and valve disc to close. Existing control methods often use pressure relief commands, valve position switches, or valve stem travel as the criteria for determining shut-off completion. However, when the pressure relief branch is blocked, gas supply isolation is incomplete, residual pressure exists in the working chamber, the valve stem is stuck, or the valve disc seal fails, the control system often only provides vague results such as closing timeout or abnormal valve position, making it difficult to pinpoint the specific point of failure in the shut-off process. While some units have backup pressure relief branches, they often directly repeat the pressure relief process after the main control action fails, failing to select a control path that avoids the faulty component based on the failure location. Therefore, the backup control may still be affected by the original failure.

[0003] Furthermore, the valve stem reaching the closed position does not necessarily indicate that the valve disc has reliably seated, nor does valve disc seating necessarily indicate effective isolation between upstream and downstream media. Relying solely on mechanical position signals can easily lead to situations where the valve position indicates closure while the media continues to flow. If the fault condition is not cleared, allowing the valve to be recharged and reset may disrupt the established closed state. Therefore, continuous monitoring of pressure relief, air pressure release, mechanical closure, valve disc seating, and pipeline isolation is necessary, along with implementing corresponding fault-tolerant shut-off and reset interlocks based on the location of the failure. Summary of the Invention

[0004] This invention provides a pneumatic emergency shut-off valve method and system with failure self-diagnosis and fault-tolerant control, solving the technical problems in the background art.

[0005] This invention provides a method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control, comprising the following steps:

[0006] Step 1: Obtain the detection signal items, preset judgment parameter group and preset structural parameter group; establish the cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation;

[0007] Step 2: Receive emergency cut-off trigger, determine the emergency cut-off trigger source and the initial cut-off state group; determine the preferred pressure relief path based on the emergency cut-off trigger source, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred pressure relief path;

[0008] Step 3: Based on the initial cut-off state group, detection signal items, and preset judgment parameter group, determine the pressure release amount and valve stem closing stroke amount, and determine each state node, the formation time of each state node, and the valve stem closing state;

[0009] Step 4: Determine the first failure link based on the cut-off state transmission chain, the formation time of each state node and the corresponding allowable duration; determine the closing force margin based on the preset structural parameter set and the pressure of the pneumatic piston working chamber, and distinguish between residual pressure resistance and mechanical transmission failure based on the closing force margin.

[0010] Step 5: Determine the fault-tolerant disconnection path based on the first failed link and the failure type, execute the fault-tolerant disconnection path, and re-verify the disconnection status transmission chain;

[0011] Step 6: Based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient, and determine the pipeline process isolation status.

[0012] Step 7: Perform a status consistency check based on the pressure release, valve stem closed status, valve disc seated status, and pipeline process isolation status to determine the failure detection end and the final effective cut-off status. Then, based on the final effective cut-off status, perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking.

[0013] The present invention also provides a pneumatic emergency shut-off valve system with failure self-diagnosis and fault-tolerant control, comprising:

[0014] The state chain construction module is used to acquire detection signal items, preset judgment parameter groups and preset structural parameter groups; and to establish a cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation.

[0015] The trigger pressure relief control module is used to receive emergency cut-off triggers, determine the source of the emergency cut-off trigger and the initial cut-off state group; determine the preferred pressure relief path according to the source of the emergency cut-off trigger, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred pressure relief path;

[0016] The cut-off state determination module is used to determine the pressure release amount and valve stem closing stroke amount based on the initial cut-off state group, detection signal items and preset judgment parameter group, and to determine each state node, the formation time of each state node and the valve stem closing state.

[0017] The failure diagnosis module is used to determine the first failure link based on the cut-off state transmission chain, the formation time of each state node and the corresponding allowable duration; determine the closing force margin based on the preset structural parameter group and the pressure of the pneumatic piston working chamber; and distinguish between residual pressure hindrance and mechanical transmission failure based on the closing force margin.

[0018] The fault-tolerant path reconstruction module is used to determine the fault-tolerant cut-off path based on the first failed link and the failure type, execute the fault-tolerant cut-off path, and re-verify the cut-off status transmission chain.

[0019] The isolation status verification module is used to determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, and to determine the pipeline process isolation status.

[0020] The shut-off interlock control module is used to perform state consistency verification based on pressure release, valve stem closing status, valve disc seating status, and pipeline process isolation status, determine the failure detection end and the final effective shut-off status, and perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking based on the final effective shut-off status.

[0021] The beneficial effects of this invention are as follows: This invention establishes a cut-off state transmission chain according to the sequence of pressure relief branch opening, pneumatic piston working chamber pressure release, valve stem closing movement, valve disc seating, and pipeline process isolation. It can determine the first failure point based on the formation time of each state node, and further distinguish between residual pressure obstruction and mechanical transmission failure by using the closing force margin. This expands fault judgment from single valve position detection to the entire process of air path, mechanical transmission, and media isolation. Based on the first failure point, a fault-tolerant cut-off path can be reconstructed, allowing the activation of fault-tolerant pressure relief branches, dual-branch pressure relief, or handwheel mechanical connection mechanisms when the main control pressure relief branch fails, the working chamber residual pressure is too high, or the mechanical transmission is abnormal. By verifying the pipeline process isolation state through average verification pressure difference, leakage response coefficient, and pressure transmission coefficient, it is possible to distinguish between mechanical closure and effective media isolation. Combined with failure detection end replacement, closure locking, and reset interlocking, the cut-off state can be maintained when the detection end is abnormal, and the valve can be reopened by resupplying air before the fault is cleared. Attached Figure Description

[0022] Figure 1 This is a flowchart of a pneumatic emergency shut-off valve method with failure self-diagnosis and fault-tolerant control according to the present invention;

[0023] Figure 2 This is a schematic diagram of the mechanical structure of the pneumatic emergency shut-off valve of the present invention;

[0024] Figure 3 This is a schematic diagram of the pneumatic control path and detection unit connection of the present invention. Detailed Implementation

[0025] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0026] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of the present invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in one or more embodiments of the present invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] like Figure 1 As shown, a method for a pneumatic emergency shut-off valve with failure self-diagnosis and fault-tolerant control includes the following steps:

[0028] Step 1: Obtain the detection signal items, preset judgment parameter group and preset structural parameter group; establish the cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation;

[0029] Step 2: Receive emergency cut-off trigger, determine the emergency cut-off trigger source and the initial cut-off state group; determine the preferred pressure relief path based on the emergency cut-off trigger source, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred pressure relief path;

[0030] Step 3: Based on the initial cut-off state group, detection signal items, and preset judgment parameter group, determine the pressure release amount and valve stem closing stroke amount, and determine each state node, the formation time of each state node, and the valve stem closing state;

[0031] Step 4: Determine the first failure link based on the cut-off state transmission chain, the formation time of each state node and the corresponding allowable duration; determine the closing force margin based on the preset structural parameter set and the pressure of the pneumatic piston working chamber, and distinguish between residual pressure resistance and mechanical transmission failure based on the closing force margin.

[0032] Step 5: Determine the fault-tolerant disconnection path based on the first failed link and the failure type, execute the fault-tolerant disconnection path, and re-verify the disconnection status transmission chain;

[0033] Step 6: Based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient, and determine the pipeline process isolation status.

[0034] Step 7: Perform a status consistency check based on the pressure release, valve stem closed status, valve disc seated status, and pipeline process isolation status to determine the failure detection end and the final effective cut-off status. Then, based on the final effective cut-off status, perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking.

[0035] In one embodiment of the present invention, such as Figure 2 As shown, the pneumatic emergency shut-off valve body 100 includes a valve body 110, a valve seat 120, a valve disc 130, a valve stem 140, a pneumatic piston 150, a pneumatic piston action chamber 160, a return spring 170, and a handwheel mechanical connection mechanism 180. The valve disc 130 is disposed within the valve body 110 and is positioned opposite the valve seat 120. The valve disc 130 is connected to the pneumatic piston 150 via the valve stem 140. The return spring 170 is positioned along the closing direction of the valve stem 140. The pressure within the pneumatic piston action chamber 160 acts on the pneumatic piston 150 and is opposite to the closing force generated by the return spring 170. When the pressure within the pneumatic piston action chamber 160 is released, the return spring 170 drives the valve stem 140 to move along the closing direction, causing the valve disc 130 to contact the valve seat 120.

[0036] A handwheel mechanical control mechanism 180 is located at the upper end of the valve stem 140 and is connected to the valve stem 140 via a one-way connecting sleeve 181. The one-way connecting sleeve 181 only transmits the closing direction displacement generated by the handwheel mechanical control mechanism 180 to the valve stem 140. A mechanical locking component 182 is located between the handwheel mechanical control mechanism 180 and the valve stem 140, and restricts the valve stem 140 from generating opening direction displacement after the handwheel mechanical control mechanism 180 has completed the closing direction control.

[0037] like Figure 3As shown, the gas source 200 is connected to the pneumatic piston working chamber 160 through the gas supply isolation branch 210, and the gas supply isolation branch 210 is equipped with a gas supply isolation branch status detection unit 211. The main control pressure relief branch 220, the fault-tolerant pressure relief branch 230, and the fusible thermal trigger pressure relief branch 240 are respectively connected to the pneumatic piston working chamber 160. Among them, the main control pressure relief branch 220 and the fault-tolerant pressure relief branch 230 respectively adopt independent control elements and independent connecting pipelines, and release the gas in the pneumatic piston working chamber 160 through their respective exhaust ends.

[0038] The main control pressure relief branch 220 is equipped with a main control pressure relief branch status detection unit 221, the fault-tolerant pressure relief branch 230 is equipped with a fault-tolerant pressure relief branch status detection unit 231, and the fusible thermal trigger pressure relief branch 240 is equipped with a fusible thermal trigger pressure relief branch status detection unit 241. The pneumatic piston action chamber pressure detection unit 310 is connected to the pneumatic piston action chamber 160, the valve stem position detection unit 320 is set at the corresponding position of the valve stem 140, and the valve disc seating detection unit 330 is set at the corresponding position of the valve disc 130 or the valve seat 120.

[0039] An upstream process pressure detection unit 340 is located on the medium inlet side of the pneumatic emergency shut-off valve body 100, and a downstream process pressure detection unit 350 is located on the medium outlet side of the pneumatic emergency shut-off valve body 100. The downstream pressure replenishment path is connected to the downstream pipeline of the pneumatic emergency shut-off valve body 100, and a downstream pressure replenishment path status detection unit 360 and a downstream pressure replenishment path control valve 361 are provided. A handwheel mechanical connection mechanism status detection unit 370 is located at the corresponding position of the handwheel mechanical connection mechanism 180.

[0040] The status detection units 211 (supply isolation branch), 221 (main control pressure relief branch), 231 (fault-tolerant pressure relief branch), 241 (fusible heat-triggered pressure relief branch), 310 (pneumatic piston action chamber pressure detection unit), 320 (valve stem position detection unit), 330 (valve disc seating detection unit), 340 (upstream process pressure detection unit), 350 (downstream process pressure detection unit), 360 (downstream pressure replenishment path status detection unit), and 370 (handwheel mechanical connection mechanism status detection unit) are all connected to the controller 400. The controller 400 establishes control connections with the gas supply isolation branch 210, the main control pressure relief branch 220, the fault-tolerant pressure relief branch 231, the downstream pressure replenishment path control valve 361, and the mechanical locking component 182.

[0041] In one embodiment of the present invention, detection signal items, preset judgment parameter groups, and preset structural parameter groups are acquired, and a cut-off state transmission chain is established in the order of pressure relief branch conduction, pneumatic piston working chamber pressure release, valve stem closing movement, valve disc seating, and pipeline process isolation. The cut-off state transmission chain is a set of state nodes set sequentially according to the control actions, air pressure changes, mechanical displacements, and media isolation results during the actual cut-off process of the pneumatic emergency shut-off valve. After the previous state node is formed, it begins to determine whether the next state node is formed within the corresponding allowable time.

[0042] Specifically, the connections of the gas supply isolation branch, main control pressure relief branch, fault-tolerant pressure relief branch, fusible heat-triggered pressure relief branch, pneumatic piston working chamber, return spring, valve stem, valve disc, valve seat, and handwheel mechanical connection mechanism are obtained. The gas supply isolation branch is located between the gas source and the pneumatic piston working chamber. After the gas supply isolation branch enters the isolation state, it blocks the gas source from supplying gas to the pneumatic piston working chamber. The main control pressure relief branch and the fault-tolerant pressure relief branch are respectively connected to the pneumatic piston working chamber. They use independent control elements and pressure relief channels. When the control element or pressure relief channel corresponding to the main control pressure relief branch fails, the fault-tolerant pressure relief branch can still release the gas in the pneumatic piston working chamber.

[0043] The fusible thermal trigger pressure relief branch is connected to the pneumatic piston's operating chamber. The fusible component changes the on / off state of this branch after reaching the set operating temperature. The return spring is positioned along the direction of movement of the pneumatic piston or valve stem. After the pressure in the pneumatic piston's operating chamber decreases, the return spring releases its elastic force and moves the valve stem towards the closing direction. The valve stem further drives the valve disc to contact the valve seat. The handwheel mechanical connection mechanism is connected to the valve stem via a one-way connecting sleeve. The one-way connecting sleeve only transmits mechanical displacement in the valve closing direction, preventing reverse valve opening during the mechanical connection process.

[0044] Further, the detection signal items are acquired. These include the status of the gas supply isolation branch, the status of each pressure relief branch, the pressure in the pneumatic piston working chamber, the valve stem position, the valve disc seating status, the upstream process pressure, the downstream process pressure, the downstream pressure replenishment path status, and the status of the handwheel mechanical connection mechanism. The status of each pressure relief branch includes the status of the main control pressure relief branch, the fault-tolerant pressure relief branch, and the fusible thermal trigger pressure relief branch. Each branch status includes at least a conducting state and a blocking state. The pneumatic piston working chamber pressure is the real-time gauge pressure within the pneumatic piston working chamber; the valve stem position is the axial position of the valve stem relative to its fully open position; and the valve disc seating status is the detection result of the valve disc contacting the valve seat.

[0045] The upstream and downstream process pressures are the pressures at the valve's medium inlet and outlet sides, respectively. The downstream pressure replenishment path status indicates whether there are other pathways that bypass the pneumatic emergency shut-off valve to replenish medium pressure in the downstream pipeline. The handwheel mechanical connection mechanism status includes standby, engaged, and locked states. The standby state indicates that the one-way connecting sleeve is not mechanically connected to the valve stem; the engaged state indicates that the one-way connecting sleeve is mechanically connected to the valve stem in the closing direction; and the locked state indicates that the valve stem is held in the current closed position.

[0046] In practical implementation, position feedback units can be installed in the gas supply isolation branch, the main control pressure relief branch, and the fault-tolerant pressure relief branch; a pressure detection unit can be installed in the pneumatic piston working chamber; a linear displacement detection unit can be installed in the valve stem; a seat detection unit can be installed at the corresponding position of the valve disc or valve seat; and pressure detection units can be installed in the upstream and downstream pipelines of the valve. Each detection unit collects data according to the same control cycle, ensuring a one-to-one correspondence between the branch state, pneumatic piston working chamber pressure, valve stem position, valve disc seat state, and upstream and downstream process pressures at the same control moment. The preferred control cycle range is 5 milliseconds to 50 milliseconds, with a preferred value of 10 milliseconds.

[0047] Further, a preset set of judgment parameters is obtained. This preset set of judgment parameters includes the allowable duration for pressure relief branch switching, the allowable duration for pressure release, the allowable duration for valve stem initiation, the allowable duration for valve stem closure, the release pressure of the working chamber, the pressure release threshold, the initiation stroke threshold, the closure stroke threshold, and a preset minimum positive value. The allowable duration for pressure relief branch switching is the maximum allowable time from issuing a pressure relief control command to the actual conduction of the corresponding pressure relief branch, preferably ranging from 50 milliseconds to 300 milliseconds, with a preferred value of 100 milliseconds. The allowable duration for pressure release is the maximum allowable time from the conduction of the pressure relief branch to the pressure in the pneumatic piston's working chamber reaching the release condition, preferably ranging from 200 milliseconds to 1 second, with a preferred value of 300 milliseconds.

[0048] The allowable valve stem start-up time is the maximum time allowed from the completion of pressure release in the pneumatic piston's working chamber to the valve stem's displacement in the closing direction, preferably ranging from 200 milliseconds to 1 second, with a preferred value of 500 milliseconds. The allowable valve stem closing time is the maximum time allowed from the start of valve stem movement to reaching the closing stroke threshold, preferably ranging from 1 second to 5 seconds, with a preferred value of 2 seconds. These allowable times are pre-calibrated based on the valve diameter, pneumatic piston working chamber volume, pressure relief channel flow area, and return spring characteristics.

[0049] The preferred value for the release pressure of the working chamber is 0.05 MPa, and the preferred value for the pressure release threshold is 0.8; the preferred value for the start-up stroke threshold is 0.05; and the preferred value for the stop-down stroke threshold is 0.95. The preset minimum positive value is a fixed positive number added to the denominator in subsequent ratio calculations, and is preferably set to [value missing]. Its value is less than one-thousandth of the corresponding normal calculation amount.

[0050] The preset structural parameter set includes the valve stem fully open position, valve stem fully closed position, return spring stiffness, the correspondence between valve stem position and effective deformation of the return spring, closing direction force, effective pressure area of ​​the pneumatic piston, and maximum normal movement resistance. The correspondence between valve stem position and effective deformation of the return spring is calibrated using valve assembly dimensions and initial spring compression. The closing direction force is the resultant force generated by the weight of the valve disc and valve stem, as well as the auxiliary closing structure. The maximum normal movement resistance is the maximum allowable resistance when the valve stem, seals, and guide components move under normal conditions. For example, the fully open valve stem position can be calibrated to 0 mm, the fully closed valve stem position to 60 mm, the return spring stiffness to 18 Newtons per millimeter, and the effective pressure area of ​​the pneumatic piston to 0.003 square meters.

[0051] Finally, each state node is set in the order of pressure relief branch opening, pneumatic piston working chamber pressure release, valve stem closing and movement, valve disc sitting and pipeline process isolation, and adjacent state nodes are associated with their corresponding allowable durations to obtain the cut-off state transmission chain.

[0052] Through the above processing, the branch control status, the working chamber air pressure status, the valve stem mechanical status, and the pipeline medium status are incorporated into a unified process control sequence, so that the determination of the first failure link, the distinction between residual pressure stagnation and mechanical transmission failure, the reconstruction of fault-tolerant cut-off paths, and the reset interlock all have clear status sources and time basis.

[0053] In one embodiment of the present invention, an emergency shut-off trigger is received, the source of the emergency shut-off trigger and the initial shut-off state group are determined, a preferred pressure relief path is determined based on the source of the emergency shut-off trigger, the gas supply isolation branch is controlled to enter the isolation state, and the gas in the pneumatic piston action chamber is released through the preferred pressure relief path. An emergency shut-off trigger refers to the actual triggering event that causes the pneumatic emergency shut-off valve to switch from the normal holding state to the shut-off control state, including an emergency shut-off command from the control system, the conduction state of the fusible thermal trigger pressure relief branch, and the gas source depressurization state.

[0054] Specifically, the emergency shut-off command of the control system is output by the upper-level process control equipment, the on-site emergency stop unit, or the safety controller. The command content includes at least the target valve identifier, the command type, and the command generation time. The fusible thermal trigger pressure relief branch conduction state refers to the transition from a blocked state to a conducting state after the fusible component reaches the corresponding action condition. The air source pressure loss state refers to the air source pressure being lower than the minimum working pressure of the pneumatic emergency shut-off valve and remaining below it for a preset confirmation time. The minimum working pressure is pre-calibrated based on the effective pressure-bearing area of ​​the pneumatic piston, the return spring force, and the normal movement resistance of the valve stem. The preferred range is 40% to 70% of the rated air supply pressure, with a preferred value of 60% of the rated air supply pressure. The preset confirmation time is preferably 50 milliseconds.

[0055] Upon detection of any emergency cutoff trigger, the source type corresponding to that trigger is identified as the emergency cutoff trigger source, and the moment when the trigger condition is first met is identified as the cutoff start time. The cutoff start time is marked using the controller's unified control clock, ensuring that subsequent acquisitions of pneumatic piston working chamber pressure, valve stem position, branch status, and process pressure have the same time reference. When multiple emergency cutoff triggers occur in different control cycles, the earliest emergency cutoff trigger is identified as the emergency cutoff trigger source for this cutoff process. When multiple emergency cutoff triggers occur in the same control cycle, the emergency cutoff trigger source is determined sequentially according to the fusible thermal trigger depressurization branch conduction status, the control system emergency cutoff command, and the gas source depressurization status, while the remaining trigger states are retained as accompanying trigger records for this cutoff process.

[0056] For example, if the control cycle is 10 milliseconds, the fusible thermal trigger pressure relief branch enters the conduction state at 120 milliseconds, and the emergency cut-off command of the control system arrives at 130 milliseconds, then 120 milliseconds is determined as the cut-off start time, and the conduction state of the fusible thermal trigger pressure relief branch is determined as the emergency cut-off trigger source.

[0057] After determining the cut-off start time, the initial pressure of the pneumatic piston working chamber, the initial position of the valve stem, the initial upstream pressure, the initial downstream pressure, the initial state of the air supply isolation branch, and the initial state of each pressure relief branch are obtained to form the cut-off initial state group. The initial pressure of the pneumatic piston working chamber is the pressure reference within the pneumatic piston working chamber before the start of cut-off control. The initial position of the valve stem is the axial position of the valve stem before it begins to close. The initial upstream pressure and the initial downstream pressure are the process pressure references for the valve inlet and outlet sides, respectively. The initial states of each pressure relief branch include the initial state of the main control pressure relief branch, the initial state of the fault-tolerant pressure relief branch, and the initial state of the fusible thermal trigger pressure relief branch. Simultaneously, the initial state of the handwheel mechanical connection mechanism is recorded as an additional state item in the cut-off initial state group.

[0058] Initial data are collected synchronously according to the cut-off start time. When the deviation between the data formation time of a single detection channel and the cut-off start time is no greater than one control cycle, the detection data is assigned to the cut-off initial state group; when the deviation exceeds one control cycle, the detection channel is marked as having an initial state missing, and the first valid detection data obtained thereafter and its corresponding time are retained. For example, when the control cycle is 10 milliseconds, the pneumatic piston action chamber pressure formed within 10 milliseconds before and after the cut-off start time is assigned to the same cut-off initial state group.

[0059] Furthermore, the preferred pressure relief path is determined based on the emergency cutoff trigger source. When the emergency cutoff trigger source is an emergency cutoff command from the control system, the main control pressure relief branch is determined as the preferred pressure relief path; when the emergency cutoff trigger source is a gas source depressurization state, the main control pressure relief branch is also determined as the preferred pressure relief path to release the compressed gas remaining in the pneumatic piston working chamber; when the emergency cutoff trigger source is a fusible thermal trigger pressure relief branch in a conducting state, the fusible thermal trigger pressure relief branch is determined as the preferred pressure relief path and its actual conducting state is maintained.

[0060] After determining the preferred depressurization path, an isolation control command is first output to the gas supply isolation branch, followed by a depressurization control command to the preferred depressurization path, thus blocking the gas supply replenishment path and simultaneously releasing the gas in the pneumatic piston's working chamber. The gas supply isolation control command and the depressurization control command are output sequentially within the same control cycle, with the time interval between their outputs preferably not exceeding one control cycle. This process only responds to actual emergency shut-off triggers and does not additionally drive the pneumatic emergency shut-off valve to perform specialized diagnostic actions.

[0061] The actual conduction state of the preferred pressure relief path is obtained through the position feedback unit of the corresponding branch, and the moment when the preferred pressure relief path first forms a stable conduction state is determined as the conduction state formation moment. A stable conduction state means that the conduction feedback of the preferred pressure relief path continues for a preset number of confirmation cycles, preferably 3 control cycles. When the preferred pressure relief path fails to form a stable conduction state within the allowable transition time of the pressure relief branch, the non-conducting state of the preferred pressure relief path and its corresponding duration are recorded for subsequent determination of the first failure link based on the disconnection state transmission chain.

[0062] From the moment the cut-off begins, the gas supply permission is set to the prohibited state. The controller will not accept control requests to re-supply gas to the pneumatic piston's working chamber until the final effective cut-off state is formed or the corresponding failure state is cleared.

[0063] Through the above processing, emergency cut-off triggering, initial state acquisition, preferred pressure relief path selection, gas supply isolation and pressure relief execution are incorporated into a unified process control sequence, providing a unified starting point for determining the subsequent pressure release amount, valve stem closing stroke amount and the formation time of each state node, and reducing the interference caused by continuous gas supply replenishment or multiple trigger state conflicts on failure self-diagnosis and fault-tolerant control.

[0064] In one embodiment of the present invention, the pressure release amount and the valve stem closing stroke amount are determined based on the initial cut-off state group, the detection signal item, and the preset judgment parameter group, and accordingly the pressure release node of the pneumatic piston working chamber, the valve stem closing movement node, the formation time of each state node, and the valve stem closing state are determined. The pressure release amount characterizes the degree of completion of the pressure change from the initial pressure at the cut-off start time to the pressure change in the working chamber of the pneumatic piston, and the valve stem closing stroke amount characterizes the degree of completion of the valve stem movement from the fully open position to the fully closed position. Both are limited to between 0 and 1.

[0065] Specifically, the initial pressure of the pneumatic piston working chamber is extracted from the initial state group of the cut-off operation, and the current pressure of the pneumatic piston working chamber is continuously obtained from the detection signal items. The current pressure of the pneumatic piston working chamber is the gauge pressure of the pneumatic piston working chamber measured by the pressure detection unit at the current control moment. The current pressure of each pneumatic piston working chamber is collected synchronously with the valve stem position according to the aforementioned control cycle, and is marked with the same control clock as the cut-off start time.

[0066] When the initial pressure in the working chamber of the pneumatic piston is greater than the release pressure of the working chamber, first subtract the current pressure of the working chamber from the initial pressure of the working chamber to obtain the current pressure drop. Then, subtract the release pressure of the working chamber from the initial pressure of the working chamber to obtain the reference pressure release range. Add the preset minimum positive value to the reference pressure release range to obtain the denominator for calculating the pressure release amount. Finally, divide the current pressure drop by the denominator for calculating the pressure release amount to obtain the pressure release amount.

[0067] When the initial pressure in the pneumatic piston's working chamber is not greater than the chamber's release pressure, it indicates that the pressure release condition has been met at the start of the cutoff. The pressure release amount is then directly set to 1, and the aforementioned ratio calculation is no longer performed. When the calculated pressure release amount is less than 0, it is set to 0; when it is greater than 1, it is set to 1. This avoids calculation results exceeding the predetermined range when the current pressure in the pneumatic piston's working chamber is briefly higher than the initial pressure or lower than the release pressure.

[0068] Furthermore, the fully open and fully closed positions of the valve stem are obtained from the preset structural parameter set, and the current position of the valve stem is continuously obtained from the detection signal items. The fully open and fully closed positions of the valve stem are obtained through position calibration after valve assembly, and both use the same axial coordinate reference. The initial position of the valve stem is used to verify whether the valve stem is within the preset opening range at the start of the shut-off. When the initial position of the valve stem deviates from the fully open position by more than the preset initial position deviation, an initial position abnormality is recorded, but the valve stem closing stroke is still determined according to the fully open and fully closed positions. The preferred range of the preset initial position deviation is 1% to 5% of the total valve stem stroke, with a preferred value of 3%.

[0069] To determine the valve stem closing stroke, first subtract the valve stem fully open position from the current valve stem position and take the absolute value to obtain the current closing displacement. Then, subtract the valve stem fully open position from the fully closed position and take the absolute value to obtain the total valve stem closing stroke. Add the preset minimum positive value to the total valve stem closing stroke to obtain the denominator for calculating the valve stem closing stroke. Finally, remove the current closed position and use the denominator of the valve stem closing stroke calculation to obtain the valve stem closing stroke.

[0070] Furthermore, the pressure release amount is compared with the pressure release threshold. When the pressure release amount first reaches the pressure release threshold and remains at the preset confirmation cycle number, the formation of the pressure release node in the pneumatic piston working chamber is determined, and the moment when the pressure release threshold is first reached is determined as the formation moment of the pressure release node in the pneumatic piston working chamber.

[0071] The valve stem closing stroke is compared with the starting stroke threshold and the closing stroke threshold, respectively. When the valve stem closing stroke first reaches the starting stroke threshold and remains there for a preset number of confirmation cycles, the valve stem closing movement node is determined to have formed, and the moment when the starting stroke threshold is first reached is determined to be the formation moment of the valve stem closing movement node. When the valve stem closing stroke reaches the closing stroke threshold and remains there for a preset number of confirmation cycles, the valve stem closing state is determined to be established.

[0072] Throughout the entire shut-off process, the pressure release amount, valve stem closing stroke amount, formation time of the pressure release node of the pneumatic piston action chamber, formation time of the valve stem closing movement node, and valve stem closing state are continuously recorded at each control moment, forming a process record corresponding to the pneumatic pressure change and mechanical closing action.

[0073] Through the above processing, the depressurization process of the pneumatic piston working chamber and the closing process of the valve stem are converted into continuous state quantities within a unified range. This enables the determination of the first failure link based on the formation sequence and corresponding allowable duration of each state node, and provides continuous and traceable process control data for the determination of residual pressure stagnation, mechanical transmission failure, and fault-tolerant cut-off path.

[0074] In one embodiment of the present invention, the first failure link is determined based on the cutoff state transmission chain, the formation time of each state node, and the corresponding allowable duration. The closing force margin is determined based on a preset set of structural parameters and the pressure in the pneumatic piston's working chamber. The closing force margin is used to distinguish between residual pressure blockage and mechanical transmission failure. The first failure link refers to the physical link between two adjacent state nodes in the cutoff state transmission chain that fails to complete the state transmission according to the predetermined sequence, starting from the emergency cutoff trigger. By prioritizing the determination of the location where the first anomaly occurs, multiple subsequent components are avoided from being simultaneously judged as failed before the next state node is formed.

[0075] Specifically, each state node is verified step-by-step in the order of pressure relief branch connection, pneumatic piston working chamber pressure release, valve stem closing movement, valve disc seating, and pipeline process isolation. For every two adjacent state nodes, the formation time of the previous state node is used as the timing start point. The formation time of the subsequent state node is subtracted from the formation time of the previous state node to obtain the corresponding state transmission time. This state transmission time is then compared with the corresponding allowable time. If the previous state node has been formed but the subsequent state node has not been formed, and the duration elapsed since the formation time of the previous state node exceeds the corresponding allowable time, the subsequent state node is determined as the first state node that has not been formed within the corresponding allowable time.

[0076] Specifically, the duration between the formation of the pressure relief control command and the formation of the pressure relief branch connection node is compared with the allowable duration of the pressure relief branch conversion; the duration between the formation of the pressure relief branch connection node and the formation of the pneumatic piston action chamber pressure release node is compared with the allowable pressure release duration; the duration between the formation of the pneumatic piston action chamber pressure release node and the formation of the valve stem closing movement node is compared with the allowable valve stem start duration; and the duration between the formation of the valve stem closing movement node and the formation of the valve stem closed state is compared with the allowable valve stem closing duration.

[0077] Each corresponding allowable duration adopts the corresponding value in the aforementioned preset judgment parameter group, and is calibrated through the normal cut-off process based on the diameter of the pneumatic emergency shut-off valve, the volume of the pneumatic piston working chamber, the flow area of ​​the pressure relief channel, the total closing stroke of the valve stem, and the characteristics of the return spring, and is higher than the maximum value of the corresponding normal state transmission duration.

[0078] When the preferred pressure relief path fails to establish a conductive state within the allowable switching time of the pressure relief branch, the connection between the pressure relief control command and the pressure relief branch connection node is identified as the first failure link. When the pressure relief branch connection node has been established, but the pressure release amount has not reached the pressure release threshold within the allowable pressure release time, the connection between the pressure relief branch connection node and the pneumatic piston action chamber pressure release node is identified as the first failure link. When the pneumatic piston action chamber pressure release node has been established, but the valve stem closing stroke has not reached the starting stroke threshold within the allowable valve stem starting time, the connection between the pneumatic piston action chamber pressure release node and the valve stem closing movement node is identified as the first failure link. When the valve stem closing movement node has been established, but the valve stem closing stroke has not reached the closing stroke threshold within the allowable valve stem closing time, the connection between the valve stem closing movement node and the valve disc seating node is identified as the first failure link.

[0079] When the valve stem closing stroke reaches the closing stroke threshold and forms a valve stem closed state, but the valve disc seating state has not yet formed, the completed closing stroke of the valve stem is not directly negated. Instead, the valve disc seating state is marked as abnormal, while the valve stem closed state is retained. An abnormal valve disc seating state indicates that the valve disc seating detection terminal has not output a detection result matching the valve stem closed state. This can be caused by either the valve disc not actually seating or the valve disc seating detection terminal malfunctioning. These two situations are cross-judged in subsequent steps based on the pipeline process isolation status. Once the valve disc seating state is formed, the pipeline process isolation status is obtained through subsequent process isolation verification. If the pipeline process isolation status is not established, then during the re-verification of the disconnection state transmission chain, the link between the valve disc seating node and the pipeline process isolation node is identified as the first failed link.

[0080] For cases where the pressure in the pneumatic piston's working chamber has decreased, but the valve stem has not started to move or has stopped moving during the closing process, the closing force margin needs to be further determined. First, based on the current position of the valve stem and the correspondence between the valve stem position and the effective deformation of the return spring, the current effective deformation of the return spring is determined. The return spring stiffness is then multiplied by the current effective deformation of the return spring to obtain the current force of the return spring.

[0081] Based on the current valve stem position, current sealing tightness, upstream process pressure, and downstream process pressure, a reference value for the current normal motion resistance is determined from a preset normal resistance mapping relationship. The current sealing tightness is determined based on the positional difference between the current valve stem position and the preset initial contact position of the valve disc. The preset normal resistance mapping relationship is obtained by calibrating the normal closing action data of the pneumatic emergency shut-off valve under different valve stem positions, different upstream and downstream pressure differences, and different sealing tightness. The current normal motion resistance reference value does not include abnormal resistance caused by mechanical jamming, component deformation, or foreign object blockage.

[0082] Multiply the pressure in the working chamber of the pneumatic piston by the effective pressure-bearing area of ​​the pneumatic piston to obtain the reverse force corresponding to the pressure in the working chamber of the pneumatic piston. Add the current force of the return spring to the closing force, and then subtract the reverse force corresponding to the pressure in the working chamber of the pneumatic piston and the current normal motion resistance reference value to obtain the closing force margin.

[0083] The closing force margin can be expressed as: ,in, Indicates time The corresponding closing force margin, in Newtons; This indicates the stiffness of the return spring, expressed in Newtons per millimeter. Indicates time The corresponding effective deformation of the return spring, in millimeters, is determined based on the current position of the valve stem and the correspondence between the valve stem position and the effective deformation of the return spring. The closing force is represented by the combined weight of the valve disc, valve stem, and auxiliary closing structure, and is expressed in Newtons. This indicates the effective pressure-bearing area of ​​the pneumatic piston, in square meters. Indicates time The current gauge pressure of the corresponding pneumatic piston working chamber is converted to Pascals and then used in the calculation. The reference value for the current normal motion resistance at time t is expressed in Newtons. It is determined based on the current valve stem position, current sealing tightness, upstream process pressure, downstream process pressure, and a preset normal resistance mapping relationship. The closing force margin represents the remaining force that can continue to drive the valve stem to move in the closing direction after deducting the reverse force corresponding to the pressure in the pneumatic piston's working chamber and the maximum normal motion resistance.

[0084] The stiffness of the return spring and the effective pressure area of ​​the pneumatic piston are determined according to the valve structure dimensions. The maximum normal motion resistance is calibrated based on normal operation data under different medium pressures, sealing tightness, and valve stem positions. Its preferred value is 1.1 to 1.3 times the maximum measured motion resistance during normal operation, with a preferred value of 1.2 times.

[0085] When the closing force margin is not greater than zero, and the current pressure in the pneumatic piston working chamber is greater than the current allowable working chamber pressure corresponding to the current valve stem position, a residual pressure hindrance candidate state is determined, and the main control pressure relief branch and the fault-tolerant pressure relief branch are simultaneously activated to continue releasing gas from the pneumatic piston working chamber. During the continued pressure relief process, when the pressure in the pneumatic piston working chamber decreases, causing the closing force margin to change from not greater than zero to greater than zero, and the valve stem subsequently undergoes a closing direction displacement within the allowable valve stem start-up time, the failure type is determined to be residual pressure hindrance.

[0086] Specifically, the return spring stiffness is multiplied by the effective deformation of the return spring corresponding to the current valve stem position to obtain the current force of the return spring. The current force of the return spring is added to the closing direction force, and then the current normal motion resistance reference value is subtracted to obtain the remaining closing force that can be used to resist the reverse action of the pneumatic piston working chamber pressure under the current valve stem position. The remaining closing force is divided by the effective pressure area of ​​the pneumatic piston to obtain the current allowable working chamber pressure.

[0087] The current permissible working chamber pressure represents the upper limit of the pneumatic piston working chamber pressure that, under the current valve stem position and current normal motion resistance conditions, can still maintain the valve stem's normal closing tendency. When the current pressure of the pneumatic piston working chamber is not lower than the current permissible working chamber pressure, it indicates that residual air pressure may cause insufficient closing force, thus identifying a candidate state of residual pressure blockage. When the current pressure of the pneumatic piston working chamber is lower than the current permissible working chamber pressure, and the valve stem still has not produced a closing direction displacement within the corresponding permissible time, the failure type is determined to be mechanical transmission failure.

[0088] When the closing force margin is greater than zero, but the valve stem does not displace in the closing direction within the corresponding allowable time, the failure type is determined to be mechanical transmission failure. Mechanical transmission failure corresponds to anomalies in the transmission path of the pneumatic piston, valve stem, connecting sleeve, guide component, or valve disc. When the pressure in the pneumatic piston's working chamber has reached the working chamber's release pressure, but the closing force margin is still not greater than zero, it is not directly determined to be residual pressure hindrance. Instead, the current state is determined to be an anomaly of insufficient closing force, and the state of the return spring, the medium's force, and the mechanical transmission path are further verified.

[0089] Through the above processing, the position of the first interrupted state transmission is determined on the unified cut-off state transmission chain. Combined with the closing force margin, the insufficient closing conditions caused by pneumatic residual pressure and the abnormality of mechanical transmission path are distinguished. This allows the subsequent fault-tolerant cut-off path to be reconstructed according to the first failed link and the failure type, avoiding the repeated execution of the same control on the already failed pressure relief branch or mechanical transmission path.

[0090] In one embodiment of the present invention, a fault-tolerant cutoff path is determined based on the first failure point and the failure type, the fault-tolerant cutoff path is executed, and the cutoff state transmission chain is re-verified. A fault-tolerant cutoff path refers to a control path that, after the first failure point is formed, no longer relies on the component corresponding to that first failure point, but instead calls upon other pressure relief branches or mechanical transmission paths that are in a valid state to continue completing the control path of pneumatic piston working chamber pressure release, valve stem closing movement, valve disc seating, and pipeline process isolation.

[0091] Specifically, a pre-established correspondence is established between the first failure point, the failure type, and the fault-tolerant cut-off path. When the first failure point is located between the pressure relief control command and the main control pressure relief branch connection node, or between the main control pressure relief branch connection node and the pneumatic piston working chamber pressure release node, the fault-tolerant pressure relief branch is designated as the fault-tolerant cut-off path. When the failure type is residual pressure stagnation, the main control pressure relief branch and the fault-tolerant pressure relief branch together form the fault-tolerant cut-off path. When the failure type is mechanical transmission failure, the handwheel mechanical connection mechanism is designated as the fault-tolerant cut-off path. When determining the fault-tolerant cut-off path, the gas supply isolation branch remains isolated at all times to prevent the gas source from continuing to replenish gas to the pneumatic piston working chamber.

[0092] The main control pressure relief branch and the fault-tolerant pressure relief branch are each equipped with independent control elements and pressure relief channels. The fault-tolerant pressure relief branch does not pass through the corresponding control element, connecting pipe section, and exhaust outlet of the main control pressure relief branch. When the main control pressure relief branch fails to conduct within the allowed switching time of the pressure relief branch, the main control pressure relief branch is no longer used as the valid pressure relief basis for this cut-off process. A conduction control command is output to the fault-tolerant pressure relief branch, and the status of the fault-tolerant pressure relief branch is acquired. When the fault-tolerant pressure relief branch continuously maintains the conducting state for a preset number of confirmation cycles, it is determined that the fault-tolerant pressure relief branch has formed an effective conduction.

[0093] When both the main control pressure relief branch and the fault-tolerant pressure relief branch are in the conducting state, but the pressure release amount does not reach the pressure release threshold within the allowable pressure release time, the actual isolation state of the gas supply isolation branch is verified. The actual isolation state of the gas supply isolation branch means that the gas supply isolation branch not only outputs isolation feedback, but also blocks the transmission of pressure from the gas source side to the pneumatic piston working chamber. In specific verification, the state of the gas supply isolation branch is first obtained, and then the pressure of the pneumatic piston working chamber after the gas supply isolation branch enters the isolation state is obtained. When the gas supply isolation branch is in the isolation state, but the pressure of the pneumatic piston working chamber does not decrease, or the pressure of the pneumatic piston working chamber increases again after a brief decrease, it is determined that the gas supply isolation branch has not formed actual isolation, and the gas supply isolation branch is marked as a failed component.

[0094] The determination of whether the pressure in the pneumatic piston's working chamber has decreased is based on the pressure release amount and pressure release threshold. If the pressure release amount does not reach the pressure release threshold within the allowed pressure release time, it is determined that the pressure in the pneumatic piston's working chamber has not completely decreased. After the air supply isolation branch is marked as a failed component, the main control pressure relief branch and the fault-tolerant pressure relief branch remain connected, and the air supply is prohibited, without performing recharging or valve opening control.

[0095] When the failure type is residual pressure stagnation, the main control pressure relief branch and the fault-tolerant pressure relief branch are simultaneously activated to increase the effective pressure relief channel between the pneumatic piston working chamber and the external exhaust end. The closing force margin is continuously updated according to the aforementioned method for determining the closing force margin. In each control cycle, the current effective deformation of the return spring is determined based on the current position of the valve stem. The return spring stiffness is multiplied by the current effective deformation of the return spring to obtain the current force of the return spring. The current force of the return spring is then added to the closing direction force, and the product of the pneumatic piston working chamber pressure and the effective pressure-bearing area of ​​the pneumatic piston is subtracted. Finally, the maximum normal motion resistance is subtracted to obtain the closing force margin for the current control cycle.

[0096] When the closing force margin changes from not greater than zero to greater than zero and is continuously maintained at the preset force margin confirmation cycle number, it is determined that the residual pressure blocking condition has been released. The current position of the valve stem is then reacquired and the valve stem closing stroke is determined. The preset force margin confirmation cycle number is preferably 3 control cycles.

[0097] When the failure type is mechanical transmission failure, maintain the air supply isolation branch in an isolated state and keep all effective pressure relief branches in a conductive state to prevent the residual pressure in the pneumatic piston's working chamber from generating a continuous reverse force. Release the standby constraint of the handwheel mechanical connection mechanism, allowing the one-way connecting sleeve to enter the engagement position along the valve stem axis, and confirm through the engagement state detection unit that the one-way connecting sleeve has established a mechanical connection with the valve stem. The one-way connecting sleeve only transmits mechanical displacement in the closing direction; when the handwheel mechanical connection mechanism generates reverse displacement, the one-way connecting sleeve does not transmit valve opening action to the valve stem.

[0098] After the handwheel mechanical takeover mechanism is engaged, it continuously applies a closing mechanical action to the valve stem and obtains the current position of the valve stem. When the valve stem closing stroke increases again, it is determined that the handwheel mechanical takeover mechanism has taken over the original pneumatic mechanical transmission path. If the handwheel mechanical takeover mechanism is engaged, but the valve stem closing stroke does not increase within the valve stem's allowable start-up time, it is determined that the mechanical transmission failure extends to the valve stem or valve disc actuation part. The gas supply is isolated, the pressure relief branch is open, and the handwheel mechanical takeover mechanism is engaged, and normal opening is prohibited.

[0099] After executing the fault-tolerant cutoff path, determine the start time of the fault-tolerant verification and re-verify the cutoff state transmission chain starting from the pressure release node of the pneumatic piston working chamber. During re-verification, sequentially check whether the pressure release amount reaches the pressure release threshold, whether the valve stem closing stroke reaches the start stroke threshold and the closing stroke threshold, and whether the valve disc seating state is formed, and re-record the formation time of each state node. The allowable duration corresponding to each state node is based on the formation time of the previous state node during the re-verification process, and does not use the duration already elapsed before the execution of the fault-tolerant cutoff path.

[0100] When the valve stem is closed after recalibration but the valve disc is seated, the return spring and handwheel mechanical connection mechanism maintain the valve stem's closing direction constraint, and the pipeline process isolation verification begins. When the valve disc is seated but the pipeline process isolation state is not formed, at least one effective pressure relief branch remains open, the gas supply isolation branch remains isolated, and the handwheel mechanical connection mechanism remains locked.

[0101] Through the above processing, the location result of the first failure link directly corresponds to the selection of the fault-tolerant cut-off path, and after the fault-tolerant cut-off path is executed, the same cut-off state transmission chain is reused to verify the actual cut-off process, avoiding the judgment that the fault-tolerant cut-off is completed simply because the fault-tolerant branch has been connected.

[0102] In one embodiment of the present invention, the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient are determined based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, and the pipeline process isolation status is determined. The pipeline process isolation status indicates whether a connecting path capable of transmitting medium pressure still exists between the upstream and downstream sides of the pneumatic emergency shut-off valve after it has completed mechanical closure. This status differs from the valve stem closed state and the valve disc seated state. The valve stem closed state only reflects the valve stem's stroke being complete, and the valve disc seated state only reflects the valve disc contacting the valve seat; neither directly represents that the medium has been effectively isolated.

[0103] Specifically, once either the valve stem is closed or the valve disc is seated, the moment of formation of that state is defined as the verification preparation moment, and the process isolation verification period is determined after a preset stabilization waiting time. The preset stabilization waiting time is the time it takes for short-term pressure disturbances in the upstream and downstream pipelines to decay after the valve stem or valve disc completes its closing action; a value of 0.5 seconds is preferred. The duration of the process isolation verification period is preferably 5 seconds, and its value is predetermined based on the valve diameter, upstream and downstream pipeline volume, media compressibility, and pressure detection unit response time.

[0104] During the process isolation verification period, the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status are synchronously acquired according to the aforementioned control cycle. When the downstream pressure replenishment path is in the open state, the increase in downstream process pressure may be caused by pressure replenishment from other pathways, and cannot be directly used as evidence of media leakage between the valve disc and valve seat. Therefore, the leakage response coefficient is determined only when the downstream pressure replenishment path is in the closed state.

[0105] When determining the average verification pressure difference, the difference between the upstream process pressure and the downstream process pressure at each sampling time during the process isolation verification period is calculated. The pressure differences corresponding to each sampling time are added together and then divided by the number of sampling times involved in the calculation to obtain the average verification pressure difference.

[0106] The average verification pressure difference can be expressed as: ,in, This represents the average verification pressure difference during the process isolation verification period, expressed in megapascals (MPa). This indicates the number of valid sampling points used in the calculation during the process isolation verification period; Indicates the sequential number of the valid sampling points; Indicates the first One valid sampling time; Indicates the first The upstream process pressure corresponding to each valid sampling time, in megapascals; Indicates the first The downstream process pressure corresponding to each valid sampling time is expressed in megapascals (MPa). The average verification differential pressure reflects the average pressure condition that supports isolation judgment between the upstream and downstream of the valve during the entire process isolation verification period. When the upstream process pressure is less than the downstream process pressure at a particular sampling time, the actual difference at that sampling time is retained, and its absolute value is not taken separately, to avoid the reverse differential pressure being incorrectly included in the positive isolation condition.

[0107] The leakage response coefficient is determined when the downstream pressure replenishment path is closed and the average verification differential pressure is not less than the minimum verification differential pressure. The specific calculation process is as follows: The downstream process pressure at the end of the process isolation verification is subtracted from the downstream process pressure at the start of the process isolation verification to obtain the downstream process pressure change. When the downstream process pressure change is less than zero, the downstream process pressure increase is defined as zero; when the downstream process pressure change is not less than zero, the downstream process pressure change is defined as the downstream process pressure increase. Subsequently, the average verification differential pressure is multiplied by the duration of the process isolation verification period to obtain the differential-time product. A preset minimum positive value is added to the differential-time product to obtain the denominator for calculating the leakage response coefficient. Finally, the downstream process pressure increase is divided by the denominator of the leakage response coefficient calculation to obtain the leakage response coefficient.

[0108] The leakage response coefficient can be expressed as: ,in, This represents the leakage response coefficient, measured in seconds. The downstream process pressure corresponding to the start time of process isolation verification is expressed in megapascals. The downstream process pressure at the time when the process isolation verification ends is represented, in megapascals (MPa). Indicates the start time of process isolation verification; Indicates the end time of process isolation verification; Indicates the duration of the process isolation verification period, in seconds; Indicates the average verification pressure difference; This represents the increase in downstream process pressure. When the downstream process pressure at the end of the process isolation verification is not greater than the downstream process pressure at the start of the process isolation verification, the increase in downstream process pressure is determined to be zero.

[0109] It should be noted that the leakage response coefficient represents the rate of increase in downstream process pressure under unit average verification differential pressure and unit verification duration, with units per second. The leakage response coefficient is an empirically normalized pressure response parameter used for process isolation judgment and does not directly represent the volumetric leakage rate, mass leakage rate, or equivalent flow area of ​​the leakage path. Under the conditions that the downstream pressure replenishment path is closed, the effective volume of the downstream pipeline remains constant during the process isolation verification period, the medium type and temperature are within the preset calibration range, and there are no other medium inflow paths in the downstream pipeline, leakage medium entering the downstream pipeline through the valve disc and seat will cause the downstream process pressure to increase over time. The rate of increase in downstream process pressure is positively correlated with the degree of medium leakage and is also affected by the pressure difference between the upstream and downstream of the valve. Therefore, the leakage response coefficient is obtained by dividing the downstream process pressure increase by the average verification differential pressure and the duration of the process isolation verification period to reduce the impact of different verification differential pressures and verification durations on the isolation judgment results.

[0110] A larger leakage response coefficient indicates a faster rate of increase in downstream process pressure relative to the average verified differential pressure under the same piping configuration and media conditions, and a higher probability of media connectivity between the upstream and downstream of the valve. The leakage response coefficient is only used for process isolation assessment within the same valve model, downstream effective volume range, and media conditions; it is not used to directly determine media leakage flow rate. The leakage response coefficient is permissible through multiple closure data points of the pneumatic emergency shut-off valve under qualified sealing conditions. A preferred value is 1.1 to 1.3 times the maximum leakage response coefficient under qualified sealing conditions, and more preferably 1.2 times.

[0111] Furthermore, the upstream process pressure change during the process isolation verification period is calculated. Specifically, the upstream process pressure at the end of the process isolation verification is subtracted from the upstream process pressure at the start of the process isolation verification, and the absolute value of the difference is taken. When the upstream process pressure change reaches a preset pressure change amount, the pressure transmission coefficient is determined based on the upstream and downstream process pressure change relationship. The preferred range for the preset pressure change amount is 0.01 MPa to 0.1 MPa, with a preferred value of 0.03 MPa, which is higher than the normal fluctuation range of the upstream pressure detection unit.

[0112] When determining the pressure transfer coefficient, the absolute value of the difference between the downstream process pressure at the end of the process isolation verification and the downstream process pressure at the beginning of the process isolation verification is taken to obtain the change in downstream process pressure. The change in upstream process pressure is added to a preset minimum positive value to obtain the denominator for calculating the pressure transfer coefficient. Then, the change in downstream process pressure is divided by the denominator for calculating the pressure transfer coefficient to obtain the pressure transfer coefficient.

[0113] The pressure transmission coefficient can be expressed as: ,in, This represents the pressure transmission coefficient, which is a dimensionless parameter. The upstream process pressure corresponding to the start time of process isolation verification is expressed in megapascals. This represents the upstream process pressure at the end of the process isolation verification, in megapascals (MPA). This represents the change in upstream process pressure during the process isolation verification period. The pressure transfer coefficient represents the downstream process pressure change during the process isolation verification period. It characterizes the ratio between the upstream process pressure change and the downstream pressure change in the same direction, under conditions where independent downstream pressure disturbances are limited. The pressure transfer coefficient is an auxiliary parameter for determining the pipeline process isolation status and is not used alone to determine the causal relationship between upstream and downstream process pressure changes. A larger pressure transfer coefficient indicates a greater degree of unidirectional change in downstream process pressure with upstream process pressure under the current verification conditions, excluding independent downstream pressure disturbances, and a higher probability of pressure transfer between the upstream and downstream valves. This coefficient does not directly represent the leakage flow rate of the medium, nor is it used alone as a basis for determining whether the pipeline process isolation status is invalid. The preferred range for the allowable pressure transfer coefficient is 0.02 to 0.15, with a preferred value of 0.05. Its value is determined based on upstream and downstream pressure change data under the normal valve-closed state.

[0114] When the average verification differential pressure is less than the minimum verification differential pressure, the actual medium pressure in the pipeline remains unchanged. The pipeline process isolation state is set to pending confirmation, and the gas supply isolation, pressure relief branch conduction, and valve closure are maintained until the pipeline operation naturally generates an average verification differential pressure that meets the requirements, after which verification is re-confirmed. When the average verification differential pressure is not less than the minimum verification differential pressure, the downstream pressure replenishment path is closed, and the leakage response coefficient is not greater than the allowable leakage response coefficient, if the pressure transmission coefficient has been determined, the pipeline process isolation state is determined to be valid when the pressure transmission coefficient is not greater than the allowable pressure transmission coefficient. If the upstream process pressure change does not reach the preset pressure change and the pressure transmission coefficient has not been determined, the pipeline process isolation state is determined based on the average verification differential pressure and the leakage response coefficient. In all other cases, the pipeline process isolation state is determined to be invalid.

[0115] Through the above processing, the valve mechanical closing result and the medium isolation result are judged separately by process control, so that the subsequent state consistency verification can identify the situation where the valve stem stroke is in place but the valve disc seal fails, and provide clear process pressure basis for the determination of the failure detection end, the final effective cut-off state judgment and reset interlock.

[0116] In one embodiment of the present invention, a state consistency verification is performed based on the pressure release amount, valve stem closed state, valve disc seated state, and pipeline process isolation state to determine the failure detection end and the final effective cut-off state. Based on the final effective cut-off state, gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking are executed. State consistency verification refers to judging whether different detection results support each other according to the physical sequence of the pneumatic piston working chamber completing pressure relief, the valve stem completing its closing stroke, the valve disc and valve seat forming contact, and the upstream and downstream media being isolated.

[0117] Specifically, the pressure release amount is compared with the pressure release threshold. When the pressure release amount reaches the pressure release threshold and remains at the preset confirmation cycle number, the pressure relief completion state of the working chamber is determined to be established. The pressure relief completion state of the working chamber indicates that the air pressure in the working chamber of the pneumatic piston that was hindering the valve stem from closing has been released to a preset level. This state, together with the valve stem closing state, the valve disc sitting state, and the pipeline process isolation state, constitutes the basic state of this shut-off process.

[0118] The valve stem closing state is determined based on whether the valve stem closing stroke reaches the closing stroke threshold. The valve disc seating state is determined based on whether a stable contact signal is formed at the valve disc seating detection end. The pipeline process isolation state is determined based on the average verification differential pressure, leakage response coefficient, and pressure transmission coefficient. All basic states are associated using the same shut-off process identifier to avoid combining detection results from different shut-off processes. Each basic state must maintain a preset confirmation period after its formation before it can participate in state consistency verification.

[0119] When the pressure relief of the working chamber, the valve stem closure, the valve disc seating, and the pipeline process isolation are all established, the basic states are confirmed to be consistent. When the valve stem closure and valve disc seating are both established, but the pipeline process isolation is not established, it is determined that the pneumatic emergency shut-off valve has completed mechanical closure but has not yet formed effective media isolation. The detection end corresponding to the upstream or downstream process pressure is not directly identified as the failure detection end, and the subsequent closed and locked state is maintained. When neither the valve stem closure nor the valve disc seating is established, even if the downstream process pressure decreases, the final effective shut-off state is not confirmed, to prevent misjudgment of successful shut-off due to downstream gas usage, natural pressure relief, or other pipeline status changes.

[0120] When the pipeline process isolation state is established, and the valve disc is seated but the valve stem is closed, the valve stem position detection end is determined as the failure detection end. During this shut-off process, the original detection record of the valve stem position detection end is not changed; the valve disc seated state and the pipeline process isolation state are used together to replace the valve stem closed state in the final effective shut-off state determination. When the pipeline process isolation state is established, and the valve stem is closed but the valve disc is seated, the valve disc seated detection end is determined as the failure detection end; the valve stem closed state and the pipeline process isolation state are used together to replace the valve disc seated state in the determination.

[0121] In this context, the failure detection end refers to the detection end whose detection result is inconsistent with the rest of the mechanical state and process isolation results of the pneumatic emergency shut-off valve. The alternative processing only assesses the state of the current shut-off process; it does not rewrite the original signal of the failure detection end, nor does it remove the corresponding fault marker. For example, if the valve stem closing stroke does not reach the closing stroke threshold, but the valve disc seating state and pipeline process isolation state are both continuously established, the valve stem position detection end is identified as the failure detection end, and its original record of not reaching the closing stroke threshold is retained.

[0122] Furthermore, the final effective shut-off state is determined to be established when the pressure release reaches the pressure release threshold, the pipeline process isolation state is established, and at least one of the valve stem closing state or valve disc sitting state is established. Specifically, the determination process is as follows: first, it is determined whether the pressure release reaches the pressure release threshold; second, it is determined whether the pipeline process isolation state is established; and finally, it is determined whether at least one of the valve stem closing state or valve disc sitting state is established. The final effective shut-off state is output only when all three conditions are met simultaneously. If the pipeline process isolation state is pending confirmation, the final effective shut-off state remains pending confirmation and does not enter the normal opening process.

[0123] Once the final effective shut-off state is established, the gas supply isolation branch remains isolated, at least one verified effective pressure relief branch remains conductive, and the handwheel mechanical connection mechanism is locked. A verified effective pressure relief branch is one where, after being connected, the pressure release reaches the pressure release threshold within the allowable pressure release time. Locking the handwheel mechanical connection mechanism restricts the valve stem's opening direction displacement via a one-way connecting sleeve or corresponding locking component, keeping the valve stem in its current closed position. When the handwheel mechanical connection mechanism is engaged in mechanical connection, its current position is locked; when it is not engaged, its closing direction engagement condition is maintained, and reverse valve opening displacement is prohibited.

[0124] If the final effective shut-off state is not achieved, the gas supply prohibition state continues, recording the pressure release, valve stem closure state, valve disc seating state, pipeline process isolation state, first failure point, failure type, and already executed fault-tolerant shut-off path. The underlying states that have not yet been achieved are designated as incomplete state nodes. During the gas supply prohibition state, the pneumatic piston action chamber filling command and normal opening command are not responded to.

[0125] Finally, the reset interlock conditions are determined. Emergency cut-off trigger release means the emergency cut-off command of the control system is revoked, the fusible thermal trigger depressurization branch returns to the resettable state, and the gas source depressurization state disappears. The failure state clearing corresponding to the first failed component means the original failed component returns to normal feedback and passes the corresponding state node verification within the preset reset confirmation time; the preferred preset reset confirmation time is 3 seconds.

[0126] The absence of contradictory states among valid detection signals means that the detection signals not identified as failure detection terminals conform to the sequential relationship of the cut-off state transmission chain and continuously maintain the preset reset confirmation cycle number. The preset reset confirmation cycle number is preferably 5 control cycles. The reset interlock is released only when the emergency cut-off trigger is released, the failure state corresponding to the first failure link is cleared, the pressure release amount reaches the pressure release threshold, the valve stem is closed or the valve disc is seated, and there are no contradictory states among the valid detection signals, allowing subsequent reset and normal opening processes to proceed.

[0127] Through the above processing, the depressurization state of the working chamber, the mechanical shutdown state, and the pipeline process isolation state are incorporated into the same process control closed loop. When a single detection end fails, the remaining valid states are used to complete the cross-judgment, and the shutdown constraint and gas supply prohibition state are maintained continuously when the cut-off result is not confirmed or the fault is not cleared.

[0128] The present invention also provides a pneumatic emergency shut-off valve system with failure self-diagnosis and fault-tolerant control, comprising:

[0129] The state chain construction module is used to acquire detection signal items, preset judgment parameter groups and preset structural parameter groups; and to establish a cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation.

[0130] The trigger pressure relief control module is used to receive emergency cut-off triggers, determine the source of the emergency cut-off trigger and the initial cut-off state group; determine the preferred pressure relief path according to the source of the emergency cut-off trigger, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred pressure relief path;

[0131] The cut-off state determination module is used to determine the pressure release amount and valve stem closing stroke amount based on the initial cut-off state group, detection signal items and preset judgment parameter group, and to determine each state node, the formation time of each state node and the valve stem closing state.

[0132] The failure diagnosis module is used to determine the first failure link based on the cut-off state transmission chain, the formation time of each state node and the corresponding allowable duration; determine the closing force margin based on the preset structural parameter group and the pressure of the pneumatic piston working chamber; and distinguish between residual pressure hindrance and mechanical transmission failure based on the closing force margin.

[0133] The fault-tolerant path reconstruction module is used to determine the fault-tolerant cut-off path based on the first failed link and the failure type, execute the fault-tolerant cut-off path, and re-verify the cut-off status transmission chain.

[0134] The isolation status verification module is used to determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, and to determine the pipeline process isolation status.

[0135] The shut-off interlock control module is used to perform state consistency verification based on pressure release, valve stem closing status, valve disc seating status, and pipeline process isolation status, determine the failure detection end and the final effective shut-off status, and perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking based on the final effective shut-off status.

[0136] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of the present embodiments, all of which are within the protection scope of the present embodiments.

Claims

1. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control, characterized in that, Includes the following steps: Step 1: Obtain the detection signal items, preset judgment parameter group and preset structural parameter group; establish the cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation; Step 2: Receive emergency cutoff trigger, determine the source of the emergency cutoff trigger and the initial cutoff state group; Determine the preferred depressurization path based on the emergency cut-off trigger source, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred depressurization path. Step 3: Based on the initial cut-off state group, detection signal items, and preset judgment parameter group, determine the pressure release amount and valve stem closing stroke amount, and determine each state node, the formation time of each state node, and the valve stem closing state; Step 4: Determine the first failure link based on the cut-off state transmission chain, the formation time of each state node, and the corresponding allowable duration; The closing force margin is determined based on the preset structural parameter set and the pressure in the working chamber of the pneumatic piston, and residual pressure resistance and mechanical transmission failure are distinguished based on the closing force margin. Step 5: Determine the fault-tolerant disconnection path based on the first failed link and the failure type, execute the fault-tolerant disconnection path, and re-verify the disconnection status transmission chain; Step 6: Based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient, and determine the pipeline process isolation status. Step 7: Perform a status consistency check based on the pressure release, valve stem closed status, valve disc seated status, and pipeline process isolation status to determine the failure detection end and the final effective cut-off status. Then, based on the final effective cut-off status, perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking.

2. The method for a pneumatic emergency shut-off valve with failure self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Acquire detection signal items, preset judgment parameter groups, and preset structural parameter groups; establish a cut-off state transmission chain according to the sequence of pressure relief branch opening, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating, and pipeline process isolation, including: Step 11: Obtain the connection relationships of the gas supply isolation branch, main control pressure relief branch, fault-tolerant pressure relief branch, fusible heat-triggered pressure relief branch, pneumatic piston working chamber, return spring, valve stem, valve disc, valve seat and handwheel mechanical connection mechanism. Step 12: Obtain detection signal items, including the status of the gas supply isolation branch, the status of each pressure relief branch, the pressure of the pneumatic piston working chamber, the valve stem position, the valve disc seating status, the upstream process pressure, the downstream process pressure, the downstream pressure replenishment path status, and the status of the handwheel mechanical connection mechanism. Step 13: Obtain the preset judgment parameter set and the preset structural parameter set. The preset judgment parameter set includes the allowable time for pressure relief branch switching, the allowable time for pressure release, the allowable time for valve stem start-up, the allowable time for valve stem closure, the release pressure of the working chamber, the pressure release threshold, the start stroke threshold, the closure stroke threshold, and the preset minimum positive value. The preset structural parameter set includes the valve stem fully open position, the valve stem fully closed position, the return spring stiffness, the correspondence between the valve stem position and the effective deformation of the return spring, the closing direction force, the effective pressure-bearing area of ​​the pneumatic piston, and the maximum normal movement resistance. Step 14: Set each state node in the order of pressure relief branch opening, pneumatic piston working chamber pressure release, valve stem closing and movement, valve disc sitting and pipeline process isolation, and associate each adjacent state node with the corresponding allowable duration to obtain the cut-off state transmission chain.

3. The method for a pneumatic emergency shut-off valve with failure self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Receive an emergency cutoff trigger and determine the source of the emergency cutoff trigger and the initial cutoff state group; Based on the emergency cut-off trigger source, the preferred depressurization path is determined, the gas supply isolation branch is controlled to enter the isolation state, and the gas in the pneumatic piston action chamber is released through the preferred depressurization path, including: Step 21: Receive emergency cut-off command from the control system, the fusible heat-triggered depressurization branch conduction status or gas source depressurization status, and determine the emergency cut-off trigger source and cut-off start time. Step 22: Obtain the initial pressure of the pneumatic piston working chamber, the initial position of the valve stem, the initial pressure of the upstream, the initial pressure of the downstream, the initial state of the gas supply isolation branch, and the initial state of each pressure relief branch at the start of the cut-off, and obtain the cut-off initial state group. Step 23: When the emergency cut-off trigger source is an emergency cut-off command from the control system or a gas source depressurization state, the main control depressurization branch is determined as the preferred depressurization path; when the emergency cut-off trigger source is a fusible heat-triggered depressurization branch in a conducting state, the fusible heat-triggered depressurization branch is determined as the preferred depressurization path. Step 24: Control the gas supply isolation branch to enter the isolation state, release the gas in the pneumatic piston action chamber through the preferred pressure relief path, record the conduction state and formation time of the preferred pressure relief path, and keep the gas supply prohibited.

4. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Based on the initial cutoff state group, detection signal items, and preset judgment parameter group, determine the pressure release amount and valve stem closing stroke, and determine each state node, the formation time of each state node, and the valve stem closing state, including: Step 31: Take the difference between the initial pressure of the pneumatic piston working chamber and the current pressure of the pneumatic piston working chamber as the numerator, and add a preset minimum positive value to the difference between the initial pressure of the pneumatic piston working chamber and the release pressure of the working chamber as the denominator. Determine the pressure release amount based on the ratio of the numerator to the denominator. Step 32: Take the absolute value of the difference between the current position of the valve stem and the fully open position of the valve stem as the numerator, and add a preset minimum positive value to the absolute value of the difference between the fully closed position and the fully open position of the valve stem as the denominator. Determine the valve stem closing stroke based on the ratio of the numerator to the denominator. Step 33: When the initial pressure of the pneumatic piston working chamber is not greater than the working chamber release pressure, the pressure release amount is set to one, and the pressure release amount and the valve stem closing stroke amount are limited to between zero and one. Step 34: Based on the pressure release threshold, start stroke threshold, and close stroke threshold, determine the pressure release node of the pneumatic piston working chamber, the valve stem closing movement node, the formation time, and the valve stem closing state.

5. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control according to claim 1, characterized in that, The first failure link is determined based on the state transmission chain being cut off, the formation time of each state node, and the corresponding allowable duration. The closing force margin is determined based on the preset structural parameter set and the pressure in the pneumatic piston's working chamber. The closing force margin is then used to differentiate between residual pressure resistance and mechanical transmission failure, including: Step 41: According to the order of cutting off the state transmission chain, compare the formation time of each state node with the corresponding allowed duration to determine the first state node that was not formed within the corresponding allowed duration. Step 42: Determine the first failure link between the state node and its previous state node; Step 43: When the valve stem is closed but the valve disc is seated, determine that the valve disc is seated abnormally and retain the valve stem closed. Step 44: Determine the reference value of the current normal motion resistance based on the current position of the valve stem, the current degree of sealing tightness, the upstream process pressure, the downstream process pressure, and the preset normal resistance mapping relationship; determine the closing force margin based on the current force of the return spring, the closing direction force, the reverse force corresponding to the pressure in the pneumatic piston working chamber, and the reference value of the current normal motion resistance. Step 45: When the closing force margin is not greater than zero and the current pressure in the pneumatic piston working chamber is greater than the allowable working chamber pressure corresponding to the current valve stem position, determine the residual pressure hindrance candidate state; continue to release the gas in the pneumatic piston working chamber, and when the closing force margin turns to be greater than zero and the valve stem produces a closing direction displacement within the allowable valve stem start-up time, determine the failure type as residual pressure hindrance; when the closing force margin is greater than zero and the valve stem does not move within the corresponding allowable time, determine the failure type as mechanical transmission failure.

6. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Determine the fault-tolerant termination path based on the first failed link and the failure type, execute the fault-tolerant termination path, and re-verify the termination status transmission chain, including: Step 51: Based on the first failure point and the failure type, determine the fault-tolerant disconnection path that avoids the component corresponding to the first failure point; Step 52: When the status transmission link corresponding to the main control pressure relief branch fails, keep the gas supply isolation branch in the isolation state and conduct the fault-tolerant pressure relief branch; when both the main control pressure relief branch and the fault-tolerant pressure relief branch are conducted but the pressure in the pneumatic piston working chamber does not drop, verify the actual isolation state of the gas supply isolation branch according to the status of the gas supply isolation branch and the pressure in the pneumatic piston working chamber. Step 53: When the failure type is residual pressure stagnation, simultaneously connect the main control pressure relief branch and the fault-tolerant pressure relief branch until the closing force margin is greater than zero; when the failure type is mechanical transmission failure, make the handwheel mechanical connection mechanism establish a mechanical connection in the closing direction with the valve stem through the one-way connecting sleeve. Step 54: After executing the fault-tolerant cut-off path, re-verify the cut-off state transmission chain starting from the pressure release node of the pneumatic piston working chamber.

7. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, the average verification differential pressure, leakage response coefficient, and pressure transmission coefficient are determined, and the pipeline process isolation status is determined, including: Step 61: After the valve stem is closed or the valve disc is seated, determine the process isolation verification period and obtain the upstream process pressure, downstream process pressure and downstream pressure replenishment path status. Step 62: Determine the average verification pressure difference based on the average value of the pressure difference between the upstream process and the downstream process during the process isolation verification period; Step 63: When the downstream pressure replenishment path is closed and the average verification pressure difference reaches the minimum verification pressure difference, the leakage response coefficient is determined based on the downstream process pressure increase, the average verification pressure difference, and the duration of the process isolation verification period; when the upstream process pressure change reaches the preset pressure change, the pressure transmission coefficient is determined based on the upstream and downstream process pressure changes. Step 64: When the average verification pressure difference is less than the minimum verification pressure difference, the pipeline process isolation status is determined to be pending confirmation; otherwise, the pipeline process isolation status is determined based on the leakage response coefficient and, when the pressure transmission coefficient has been determined, in combination with the pressure transmission coefficient.

8. A method for a pneumatic emergency shut-off valve with self-diagnosis and fault-tolerant control according to claim 1, characterized in that, Based on the pressure release, valve stem closure, valve disc seating, and pipeline process isolation status, a state consistency verification is performed to determine the failure detection end and the final effective cut-off state. Based on the final effective cut-off state, gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking are implemented, including: Step 71: Perform consistency verification on pressure release, valve stem closure status, valve disc seating status, and pipeline process isolation status; Step 72: When the pipeline process isolation state is established, and only one of the valve stem closed state and valve disc seated state is established, the detection end corresponding to the non-established state is determined as the failure detection end, and the non-established state is replaced by one of the established states of pipeline process isolation state, valve stem closed state and valve disc seated state. Step 73: When the pressure release reaches the pressure release threshold, the pipeline process isolation state is established, and the valve stem is closed or the valve disc is seated, the final effective cut-off state is determined to be established. Step 74: Based on the final effective cut-off state, maintain gas supply isolation, pressure relief branch continuity, and lock the handwheel mechanical connection mechanism; Step 75: When the emergency cut-off trigger is released, the failure state corresponding to the first failure link is cleared, and there are no state contradictions among the valid detection signals, the reset interlock is released.

9. A pneumatic emergency shut-off valve system with failure self-diagnosis and fault-tolerant control, characterized in that, A method for using a pneumatic emergency shut-off valve with failure self-diagnosis and fault-tolerant control as described in any one of claims 1-8, comprising: The state chain construction module is used to acquire detection signal items, preset judgment parameter groups and preset structural parameter groups; and to establish a cut-off state transmission chain in the order of pressure relief branch conduction, pneumatic piston action chamber pressure release, valve stem closing movement, valve disc seating and pipeline process isolation. The trigger pressure relief control module is used to receive emergency cut-off triggers, determine the source of the emergency cut-off trigger and the initial cut-off state group; determine the preferred pressure relief path according to the source of the emergency cut-off trigger, control the gas supply isolation branch to enter the isolation state, and release the gas in the pneumatic piston action chamber through the preferred pressure relief path; The cut-off state determination module is used to determine the pressure release amount and valve stem closing stroke amount based on the initial cut-off state group, detection signal items and preset judgment parameter group, and to determine each state node, the formation time of each state node and the valve stem closing state. The failure diagnosis module is used to determine the first failure link based on the cut-off state transmission chain, the formation time of each state node and the corresponding allowable duration; determine the closing force margin based on the preset structural parameter group and the pressure of the pneumatic piston working chamber; and distinguish between residual pressure hindrance and mechanical transmission failure based on the closing force margin. The fault-tolerant path reconstruction module is used to determine the fault-tolerant cut-off path based on the first failed link and the failure type, execute the fault-tolerant cut-off path, and re-verify the cut-off status transmission chain. The isolation status verification module is used to determine the average verification pressure difference, leakage response coefficient, and pressure transmission coefficient based on the upstream process pressure, downstream process pressure, and downstream pressure replenishment path status during the process isolation verification period, and to determine the pipeline process isolation status. The shut-off interlock control module is used to perform state consistency verification based on pressure release, valve stem closing status, valve disc seating status, and pipeline process isolation status, determine the failure detection end and the final effective shut-off status, and perform gas supply isolation, pressure relief branch maintenance, handwheel mechanical connection mechanism locking, and reset interlocking based on the final effective shut-off status.

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