An extreme working condition valve sealing reliability test evaluation system

Abstract

The application discloses a kind of extreme working condition under valve sealing reliability test evaluation system, it is related to valve sealing test field, system includes: phase transition induced unit, for keeping the closing of the valve to be measured, build the trans-critical phase transition induced boundary of solid carbon dioxide phase transition depositing; Section extraction unit, combined with the equivalent flow capacity of matching extraction effective flow section under deposition shielding state;Deposition exposure unit, state transformation occurs to solid deposit by applying heat boundary, extract effective flow section after deposition exposure;Reliable evaluation unit, compare uncertainty, compare and calculate the sum of effective flow section after deposition exposure and effective flow section under deposition shielding state plus the numerical value of comparison uncertainty;The application effectively removes the temporary plugging interference of phase transition deposit, extracts the real leakage characterization area and generates a comprehensive evaluation result set, accurately quantifies the real sealing degradation state of valve.

Description

Technical Field

[0001] This invention relates to the field of valve sealing testing, and more specifically to a valve sealing reliability testing and evaluation system under extreme operating conditions. Background Technology

[0002] Valves are core control components in supercritical carbon dioxide transportation and high-pressure storage systems, and their sealing reliability determines the operational safety of the high-pressure pipeline network. Conventional fluid sealing performance testing generally adopts the pressure decay method or the fixed leakage rate test method. The evaluation logic is based on the fundamental assumption that the more open the channel geometry, the faster the pressure drop and the higher the leakage rate. Existing standards mostly rely on a single static measurement threshold to judge the integrity of the seal.

[0003] Under supercritical carbon dioxide testing conditions, when fluid passes through a narrow leak channel with microscopic damage, the medium cools down due to the intense confined throttling expansion and Joule-Thomson cooling effect, crossing the triple point and entering the gas-solid two-phase region, precipitating solid carbon dioxide phase change deposits. These phase change products occupy the micro-gap space, non-structurally narrowing or temporarily shielding the actual leak channel, forming a phase change deposition-type self-sealing state of the micro-gap. This deposition shielding limits the actual leak flow rate that can be detected externally; the test circuit can only collect weak flow and slow pressure drop data, causing the valve, whose internal structure has degraded, to exhibit a false appearance of safety.

[0004] Existing testing techniques rely on external static thresholds for evaluation, lacking the ability to decouple the transcritical phase transition mechanism of fluids. They are prone to accepting distorted, masking data and severely underestimate the true degree of degradation of sealing components. The technical problem this invention urgently aims to solve is: to overcome the shortcomings of existing conventional testing techniques in effectively identifying and avoiding the phase change deposition masking effect in valve sealing testing, and to eliminate the interference of temporary blockage by solid media during extreme high-pressure throttling and cooling processes on leakage evaluation, thereby accurately quantifying the true damage and degradation state of the sealing structure of the valve under service conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a valve sealing reliability testing and evaluation system under extreme operating conditions, which solves the problem that it cannot effectively identify and remove the phase change deposition masking effect, leading to the distortion of leakage evaluation caused by temporary blockage of solid media.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a valve sealing reliability testing and evaluation system under extreme operating conditions, comprising: The phase change induction unit is used to keep the valve under test closed, control the upstream inlet side to be in a supercritical state and the downstream outlet side pressure to be lower than the triple point pressure of carbon dioxide, and construct the transcritical phase change induction boundary for the precipitation of solid carbon dioxide phase change deposits. The cross-section extraction unit is used to obtain the actual volumetric flow rate and downstream leakage medium density under the transcritical phase change induced boundary, and convert them into the mass leakage rate under the deposition and shielding state. Combined with the unit area equivalent flow capacity matched according to the current thermodynamic boundary, the effective flow cross section under the deposition and shielding state is extracted. The deposition exposure unit is used to apply a thermal boundary to cause the solid carbon dioxide phase change deposit to undergo a state transformation. It obtains the actual volumetric flow rate and the density of the downstream leakage medium after deposition exposure, and converts them into the mass leakage rate after deposition exposure. It also extracts the effective flow cross section after deposition exposure by combining the equivalent flow capacity per unit area matched according to the current thermodynamic boundary. The reliable evaluation unit is used to combine the system measurement error sources and the benchmark calibration error to synthesize the effective flow cross section comparison uncertainty. It compares and calculates the effective flow cross section after deposition exposure with the effective flow cross section under deposition shielding state plus the value of the effective flow cross section comparison uncertainty, extracts the true leakage characterization area, and generates a comprehensive evaluation result set.

[0007] Preferably, the system hardware architecture includes: Pressure regulating devices and upstream medium preheating devices for providing a fluid testing environment; local thermal boundary regulating devices for applying a locally controllable thermal boundary; pressure acquisition components, temperature acquisition components, and micro-flow detection devices for acquiring underlying state parameters; physical property databases and calibration databases for storing underlying parameters; and data processors for coordinating software and hardware instruction interaction and calculation.

[0008] Preferably, the phase change induction unit keeps the valve under test closed, cuts off the valve drive source, and performs mechanical state locking; Mechanical locking maintains a constant contact pressure of the valve's internal sealing surfaces by limiting the valve with hardware or cutting off the control source, thus keeping the micro-geometry of the sealing gap unchanged.

[0009] Preferably, the cross-section extraction unit obtains the density of the downstream leaking medium, including: The cross-section extraction unit receives the downstream outlet pressure collected by the pressure acquisition component and the downstream outlet temperature collected by the temperature acquisition component through the data processor, and performs nonlinear solution based on the Span-Wagner equation of state to extract the density of the downstream leaking medium.

[0010] Preferably, the calibration database pre-stores the flow capacity benchmark value. The flow capacity benchmark value is the data obtained by array testing using calibration micropores with known benchmark flow area under the cross-arrangement boundary of different upstream inlet side pressure, upstream inlet side temperature, downstream outlet side pressure and downstream outlet side temperature, and constructed as a four-dimensional discrete grid matrix. The calibration micropores use standard flow-through plate with an inner wall surface roughness sufficient to prevent irreversible adhesion and retention of transcritical solid carbon dioxide phase change deposits.

[0011] Preferably, the data processor extracts the equivalent flow capacity per unit area from the calibration database, including: The section extraction unit uses a data processor to locate the adjacent grid nodes where the test boundary value of the current sampling period is located in the four-dimensional discrete grid matrix constructed by the calibration database, and executes a multi-dimensional interpolation algorithm to obtain the matching unit area equivalent flow capacity. If the real-time test boundary exceeds the coverage of the discrete grid matrix of the calibration database, the data processor triggers an out-of-bounds shutdown command and locks the current extraction cycle of the effective flow section, prohibiting data extrapolation to the uncalibrated operating range.

[0012] Preferably, the deposition exposure unit applies a locally controllable thermal boundary through a local thermal boundary adjustment device, including: The deposition exposure unit uses a data processor to match the corresponding solid deposition conversion reference temperature from the phase equilibrium data in the physical property database based on the downstream outlet pressure collected by the pressure acquisition component. The data processor then controls the local thermal boundary adjustment device to ensure that the wall temperature of the sealed area is greater than the conversion reference temperature of the solid deposit under the current outlet pressure, but less than the upper limit of the safe temperature. The upper limit of the safe temperature is set as the highest allowable operating temperature rating of the component with the lowest temperature resistance inside the valve under test, minus the maximum positive absolute measurement error of the temperature acquisition component, and further minus the maximum transient control overshoot of the local thermal boundary adjustment device under step response.

[0013] Preferably, the pressure acquisition component, temperature acquisition component, and micro-flow detection device establish serial communication with the data processor via an industrial bus. The data processor receives the sensing signals from each acquisition component and outputs the signals after performing a moving average filtering algorithm.

[0014] Preferably, when the effective flow cross section after deposition exposure is determined to be less than or equal to the sum of the effective flow cross section under deposition shielding and the uncertainty of the effective flow cross section comparison, the reliable evaluation unit extracts the effective flow cross section under deposition shielding as the true leakage characterization area.

[0015] Preferably, the reliable evaluation unit calculates the self-blocking influence factor by subtracting the ratio of the effective flow cross-section under the deposition shielding state to the effective flow cross-section after the deposition is exposed, based on numerical value one. The comprehensive evaluation results set includes the mass leakage rate under the deposition shielding state, the mass leakage rate after deposition exposure, the effective flow cross section under the deposition shielding state, the effective flow cross section after deposition exposure, the uncertainty of the effective flow cross section comparison, the self-blocking influence factor, and the actual leakage characterization area.

[0016] Compared with existing technologies, it has the following advantages: This solution proposes a valve sealing reliability testing and evaluation system under extreme operating conditions. Addressing the challenge of test distortion caused by temporary blockage of solid media during supercritical carbon dioxide leakage, it proposes a sealing evaluation mechanism based on active thermodynamic boundary reconstruction. The system actively induces the precipitation of solid carbon dioxide phase change deposits by constructing a transcritical boundary, and then applies a locally controllable thermal boundary to cause a state transformation of the solid deposits within the sealing gap. This design overcomes the limitations of conventional tests that rely solely on static pressure drop or flow thresholds for passive blind testing. By utilizing the execution logic of actively changing the thermodynamic state, it directly eliminates the masking interference of solid phase change products on the actual micro-leakage channels.

[0017] This solution integrates system measurement error sources and benchmark calibration errors into the core judgment logic, synthesizing the uncertainty of the effective flow cross-section. The system compares and calculates the effective flow cross-section before and after deposition exposure, combined with the error tolerance boundary, eliminating the risk of misjudgment due to basic measurement noise from the ground up. The final extracted true leakage characterization area and dimensionless influence factor accurately reflect the actual degradation status of the valve sealing pair or packing structure. This solution achieves quantitative decoupling of the phase change shielding effect under complex operating conditions, significantly improving the accuracy and objectivity of the reliability evaluation of valve seals under extreme high pressure. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the testing and evaluation process of the present invention.

[0020] Figure 3 This is a schematic diagram of the reliability evaluation and determination process of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 This application provides a valve sealing reliability testing and evaluation system under extreme operating conditions, including a phase change induction unit, a cross-section extraction unit, a deposition exposure unit, and a reliability evaluation unit. The valve sealing reliability testing and evaluation system under extreme operating conditions also includes the following hardware architecture: a pressure regulating device and an upstream medium preheating device for providing a fluid testing environment, a local thermal boundary regulating device for applying a local controllable thermal boundary, a pressure acquisition component, a temperature acquisition component, and a micro-flow detection device for acquiring underlying state parameters, a physical property database and a calibration database for storing underlying parameters, and a data processor for coordinating software and hardware instruction interaction and calculation. Please see Figure 2 In this invention, micro-flow refers to an extremely weak leakage pattern of fluid under transcritical phase change and extreme high-pressure throttling and cooling conditions; specifically, the effective detection range of the micro-flow detection device is defined as the volumetric flow rate within... to The range of this magnitude. The core of this magnitude setting lies in: when supercritical carbon dioxide flows through a valve sealing pair with microscopic damage, the actual leakage characterization area formed ( ) Usually in to At the current test differential pressure boundary, based on the throttling expansion mechanism calculation, the corresponding steady-state leakage flow rate strictly falls within the aforementioned micro-flow detection range, thus eliminating the false zero reading caused by insufficient resolution of conventional macro-flow meters under micro-leakage conditions.

[0023] Among them, the phase change induction unit is used to keep the valve under test closed, control the upstream inlet side to be in a supercritical state and the downstream outlet side pressure to be lower than the triple point pressure of carbon dioxide, and construct the transcritical phase change induction boundary for the precipitation of solid carbon dioxide phase change deposits.

[0024] The valve under test is installed between the upstream supercritical carbon dioxide test chamber and the downstream leakage receiving chamber of the test system. Ensure that the valve under test is in the normal closed state, cut off the valve under test drive source and perform mechanical state locking; specifically, for actuator-driven valves, cut off the actuator action signal and lock the current displacement; for manual valves, keep the closed position unchanged and prohibit the application of additional tightening torque.

[0025] The valve under test is a valve body device with fluid shut-off function in a supercritical carbon dioxide delivery or storage pipeline. The test circuit is a closed fluid delivery system consisting of a high-pressure gas source, pressure-bearing pipeline, and conventional sealing joints. Mechanical state locking maintains a constant contact specific pressure of the valve's internal sealing pair through hardware limit or cut-off control source, keeping the micro-geometry of the sealing micro-gap unchanged. This eliminates the interference of sealing contact stress fluctuation caused by the slight mechanical displacement of the valve's internal shut-off components due to fluid impact when high-pressure fluid is applied, providing a geometrically stable closed space for inducing the transcritical phase transition from supercritical carbon dioxide to solid. Even if the high-pressure environment in the test circuit causes the sealing pair material to undergo elastic creep that cannot be completely locked, this micro-deformation is considered a valid test edge that meets the mechanical state locking requirements because it does not trigger a substantial collapse of the fluid dynamic boundary.

[0026] The micro-gap mentioned here refers to the potential tiny leakage channels formed in valves due to micro-scratches on the sealing surface or structural degradation such as packing pores; it is an irregular leakage path that is naturally formed in valves under extreme operating conditions, and is clearly different from standard flow holes that are artificially processed.

[0027] The phase change induction unit controls the pressure regulating device and the upstream medium preheating device through the system's data processor to inject carbon dioxide test medium into the upstream test chamber, independently regulating the upstream pressure and temperature. Simultaneously, it utilizes the downstream regulating loop to ensure the pressure inside the downstream leakage receiving chamber is lower than the upstream pressure. The phase change induction unit collects current thermodynamic state parameters in real time, controlling the upstream inlet pressure to be greater than the critical pressure of carbon dioxide and the upstream inlet temperature to be greater than the critical temperature of carbon dioxide, while maintaining the downstream outlet pressure below the triple point pressure of carbon dioxide. This constructs a transcritical phase change induction boundary. The system determines the induction boundary construction is complete when the following transcritical phase change induction boundary conditions are met: In the formula, The upstream inlet pressure of the sealing micro-gap of the valve under test. The upstream inlet side temperature of the sealing micro-gap of the valve being tested. The downstream outlet pressure of the valve's sealing micro-gap. This is the critical pressure of carbon dioxide. This is the critical temperature for carbon dioxide. The pressure is the triple point pressure of carbon dioxide; the upstream inlet side pressure, upstream inlet side temperature, and downstream outlet side pressure are all collected in real time by high-precision sensors. The critical pressure, critical temperature, and triple point pressure of carbon dioxide are preset thermodynamic constants within the system.

[0028] The pressure regulating device uses a servo-driven supercritical fluid injection pump in conjunction with an electro-proportional valve, and the upstream medium preheating device uses a constant temperature heat tracing jacket wrapped around the outer wall of the upstream test chamber. Through the above hardware coordinated control, the inlet of the sealing gap is always maintained in the supercritical fluid phase region, forcing supercritical carbon dioxide to undergo restricted throttling expansion under pressure difference drive. Under the combined effect of the upstream supercritical state, the downstream outlet pressure being lower than the triple point pressure of carbon dioxide, and the throttling and cooling conditions of the sealing micro-gap, supercritical carbon dioxide undergoes restricted throttling expansion through the sealing micro-gap, causing the fluid state to transform into the gas-solid two-phase region, and solid carbon dioxide phase change deposits are precipitated when the gas-solid two-phase phase change conditions are reached, thereby forming the transcritical phase change induction conditions.

[0029] The adjustment of the downstream leakage receiving chamber pressure mainly relies on the continuous pressurization upstream and the coordinated discharge regulation of the small-range back pressure valve or precision discharge solenoid valve set in the downstream regulation circuit to ensure that the two ends of the sealing micro gap can still maintain a stable throttling expansion pressure difference under the condition of small leakage.

[0030] Phase change deposition-type micro-gap self-sealing characteristic refers to the transcritical phase change that occurs when a supercritical fluid passes through a narrow leakage channel with microscopic damage. This process causes localized cooling, resulting in the formation of solid dry ice deposits, specifically solid carbon dioxide phase change deposits. These dry ice deposits occupy the micro-gap space, reducing the effective flow cross-sectional area and creating a unique phenomenon that non-structurally narrows or temporarily shields the actual leakage channel. This characteristic is independent of the original mechanical structure of the valve under test and is a temporary state induced by the test system actively applying thermodynamic boundaries. Inducing and maintaining this state ensures that the captured initial leakage data has a definite test premise, thus providing a calculation comparison benchmark for subsequent thermal boundary adjustment to expose the actual leakage channel. While establishing the transcritical phase transition induced boundary, the temperature acquisition component simultaneously extracts and records the downstream outlet temperature. The system accurately anchors the initial supercritical thermodynamic state of the fluid before it enters the sealed microgap based on the real-time upstream inlet pressure and upstream inlet temperature. At the same time, the acquired downstream outlet pressure and downstream outlet temperature are stored in the data processor, providing a preliminary thermodynamic parameter boundary for the subsequent accurate solution of the downstream leakage medium density by calling the real gas state equation.

[0031] When performing subsequent calculations of physical property state functions, the data processor directly calls the Span-Wagner real gas equation of state to perform nonlinear solutions, which makes the fluid density values ​​obtained in the extremely high pressure and transcritical regions have real reliability. This further eliminates the calculation failures and deviations of the conventional ideal gas equation in the highly compressible region. The system's underlying layer can directly achieve accurate extraction of physical property data through mature software interfaces.

[0032] Specifically, the Span-Wagner real gas equation of state uses the Helmholtz free energy form with temperature and density as independent variables, establishing the relationship between pressure and medium density based on the current pressure and temperature conditions: in: In the formula, p is the downstream outlet pressure; T is the downstream outlet temperature; Let be the density of the downstream leaking medium to be determined; R is the carbon dioxide specific gas constant. This is the critical density of carbon dioxide; This is the critical temperature for carbon dioxide. To reduce density; The reduction temperature; Let R be the first-order partial derivative of the residual dimensionless Helmholtz free energy with respect to the reduced density. , Pick , Pick The residual dimensionless Helmholtz free energy uses a fixed set of parameters corresponding to the publicly available carbon dioxide reference equation of state. This fixed parameter set is pre-stored in a property database and does not change during the test due to the valve under test or the current test conditions. The data processor takes the pressure acquisition component's obtained value (p) and the temperature acquisition component's obtained value (T) as known inputs, and... As the variable to be solved, the positive density physical solution that satisfies the above equation of state is obtained through nonlinear numerical solution, and it is used as the current downstream leakage medium density.

[0033] The section extraction unit is used to obtain the actual volumetric flow rate and downstream leakage medium density under the transcritical phase change induced boundary, and convert them into the mass leakage rate under the deposition shielding state. Combined with the unit area equivalent flow capacity matched according to the current thermodynamic boundary, the effective flow section under the deposition shielding state is extracted.

[0034] After the phase change induction unit establishes the transcritical phase change induction boundary, the system maintains the valve under test in a mechanically locked closed state; the micro-flow detection device collects the actual volumetric flow rate of the downstream leakage condition under the deposition and shielding state in real time; the data processor receives the downstream outlet pressure and downstream outlet temperature collected by the downstream pressure acquisition component and the downstream temperature acquisition component, and calls the aforementioned real gas state equation to obtain the density of the downstream leakage medium under the deposition and shielding state. The deposition-shrouded state mentioned here refers to the condition where solid dry ice deposits exist inside the sealed micro-gap, and the dry ice entity occupies part of the channel space, resulting in the actual flowable area of ​​the leakage channel being smaller than the potential flowable area formed by the seal damage; this condition directly limits the micro-leakage flow that can be detected from the outside of the system.

[0035] The data processor multiplies the actual volumetric flow rate of the downstream leakage condition by the density of the downstream leakage medium, converting it into the mass leakage rate under the deposition-shielded state. The corresponding mass conversion relationship is as follows: In the formula, The mass leakage rate under deposition shielding conditions is expressed in kg / s. The density of the downstream leaking medium under the deposition-shrouded state, in units of ; The actual volumetric flow rate under downstream leakage conditions in the deposition-masked state is expressed in units of... ; By converting the mass leakage rate, the error caused by the nonlinear volume change at both ends of the supercritical fluid due to the violent throttling expansion can be eliminated; the system directly uses the mass conservation relationship to characterize the actual amount of carbon dioxide lost per unit time through the sealed micro-gap. After obtaining the mass leakage rate, the data processor uses the upstream inlet pressure, upstream inlet temperature, downstream outlet pressure, and downstream outlet temperature to match and extract the equivalent flow capacity per unit area corresponding to the deposition shielding state from the system's calibration database.

[0036] The calibration database pre-stores calibration micropores with known reference flow areas. These micropores were tested under various cross-boundary conditions (upstream inlet pressure, upstream inlet temperature, downstream outlet pressure, and downstream outlet temperature) and the resulting flow capacity benchmarks were constructed as a four-dimensional discrete grid matrix. The calibration micropores utilize standard flow-through orifice plates with sufficient inner wall surface roughness to prevent irreversible adhesion and retention of transcritical solid carbon dioxide phase change deposits. In one specific embodiment, the inner wall surface roughness parameter of the standard flow-through orifice plate is limited to... The mechanism for establishing this structural parameter lies in: when the surface roughness... Greater than At that time, the size of the micro-valleys on the surface of the pore wall is significantly larger than the critical radius of the solid crystal nucleus formed in the early stage of the supercritical carbon dioxide transcritical phase transition, which makes it easier for the phase transition nucleus to achieve mechanical intercalation and epitaxial growth within the micro-valleys, forming irreversible adhesion and retention; when the surface roughness is... Strictly controlled at At and below this level, the capillary force and surface free energy of the pore wall microstructure decrease significantly, failing to provide the nucleation anchors and retention friction required for stable adhesion of solid phase change deposits. Therefore, even if the fluid crosses the triple point to precipitate solid dry ice, the phase change products can only be stripped off and discharged from the pores in real time along with the hydrodynamic boundary. This completely eliminates the adhesion and retention of phase change products within the pore size from a physical mechanism perspective, ensuring that the extracted calibration data reflects pure hydrodynamic flow capacity and absolutely eliminating the interference of the temporary blockage effect of phase change deposition.

[0037] When the real-time pressure and temperature boundaries during testing are located between two adjacent discrete calibration points recorded in the calibration database, the data processor uses a linear interpolation algorithm within the calibration data coverage area to obtain the matching equivalent flow capacity per unit area, and prohibits data extrapolation to the uncalibrated operating conditions. The equivalent flow capacity per unit area characterizes the actual mass leakage capacity corresponding to a unit flow cross section under the current matched thermodynamic boundary. The system uses benchmark micro-orifice calibration data to replace the unverified ideal orifice flow model, avoiding theoretical calculation failures caused by abrupt changes in the properties of supercritical carbon dioxide.

[0038] The data processor divides the mass leakage rate under the deposition-masked state by the corresponding equivalent flow capacity per unit area to calculate the effective flow cross-section under the deposition-masked state. The corresponding cross-section extraction relationship is as follows: In the formula, The effective flow cross-section under sediment-shielded conditions, in units of ; This represents the equivalent flow capacity per unit area under sediment-shrouded conditions, expressed in units of... ; The calculated effective flow cross section is used to characterize the equivalent area that carbon dioxide can still pass through inside the sealed micro-gap when phase change deposits occupy part of the channel space. The effective flow cross section serves as a data comparison benchmark before subsequent local thermal boundary adjustment operations, providing a starting point for determining whether the actual leakage channel is blocked.

[0039] The deposition exposure unit is used to apply a thermal boundary to cause the solid carbon dioxide phase change deposit to undergo a state transformation, obtain the actual volumetric flow rate and the density of the downstream leakage medium after deposition exposure, and convert them into the mass leakage rate after deposition exposure. Combined with the equivalent flow capacity per unit area matched according to the current thermodynamic boundary, the effective flow cross section after deposition exposure is extracted.

[0040] The data processor controls the activation of the local thermal boundary adjustment device to apply a local controllable thermal boundary to the selected valve sealing area. When the test target is the valve seat sealing pair, the local thermal boundary adjustment device is arranged on the outer wall of the valve body near the valve seat sealing area. When the test target is the valve stem packing, the local thermal boundary adjustment device is arranged on the outer periphery of the stuffing box. The local thermal boundary adjustment device uses heating components such as electric heating rings, thin film heating plates, or external circulating heat exchange jackets.

[0041] The pressure acquisition component continuously monitors the outlet-side pressure during operation, while the temperature acquisition component collects the wall temperature of the sealed area in real time during the deposition exposure operation. Based on the downstream outlet-side pressure collected by the pressure acquisition component, the data processor matches the corresponding solid-state deposition conversion reference temperature from the phase equilibrium data in the property database. The data processor adjusts the duty cycle or conduction angle of the local thermal boundary adjustment device by outputting a pulse width modulation signal or a thyristor phase-shift trigger signal to regulate the heating power, ensuring that the wall temperature of the sealed area is strictly constrained within the following thermal boundary conditions: In the formula, This is the reference temperature for the transformation of solid sediments under current outlet pressure, in Kelvin. Temperature of the sealed area wall during deposition exposure operation, in Kelvin. This refers to the upper limit of the safe temperature for valve materials or seals, expressed in Kelvin (K).

[0042] The system sets the upper limit of safe temperature. The value is set as the highest allowable operating temperature rating of the component with the lowest temperature resistance inside the valve under test. Based on this, a subtraction operation is performed to subtract the maximum positive absolute measurement error of the temperature acquisition component, and further subtract the maximum transient control overshoot of the local thermal boundary adjustment device under step response. The maximum transient control overshoot value has a prior acquisition basis, which is obtained by applying a step heating command to the unloaded valve body and recording the peak value of the transient temperature response during the test preparation stage. In a specific control embodiment, this overshoot value is calibrated to be 2.5K to 4.0K. The solid-state deposition conversion reference temperature is determined based on real carbon dioxide phase equilibrium property data, that is, the sublimation point or phase transition critical temperature under the current pressure; this ensures that the solid dry ice deposits in the sealed area can fully absorb heat and sublimate or transform into a non-solid phase, thus causing the hidden real leakage channels to reappear.

[0043] When the system continuously monitors the temperature fluctuation of the sealing area wall within a preset time period (set to be 60 seconds) and finds it to be consistently less than the system's steady-state judgment range threshold (set to be ±0.5K), the system determines that the temperature is stable within the target thermal boundary range. The preset time period and steady-state judgment range threshold are used to determine whether the local thermal boundary has reached a stable sampling state. After applying a local thermal boundary to the outside of the valve under test, a heat conduction response process occurs between the valve body wall and the internal sealing area. Simultaneously, the solid carbon dioxide phase change deposit causes local temperature fluctuations in the sealing area during the endothermic conversion process. When the sealing area wall temperature remains within the target thermal boundary range for 60 consecutive seconds and the fluctuation amplitude is consistently less than ±0.5K, the system determines that the deposition exposure operation has reached a stable state and enters the leakage parameter acquisition stage after deposition exposure.

[0044] At this time, the micro-flow detection device re-collects the actual volumetric flow rate of the downstream leakage condition after the deposition exposure; the pressure acquisition component simultaneously extracts the inlet side pressure after the deposition exposure and the outlet side pressure under steady state, and the temperature acquisition component simultaneously collects the inlet side temperature and the outlet side temperature after the deposition exposure; all the above-mentioned underlying hardware components establish serial communication with the system's data processor through the RS485 industrial bus based on the Modbus-RTU protocol, and after receiving the sensing signals from each acquisition component, the data processor prioritizes the execution of the moving average filtering algorithm to eliminate periodic high-frequency noise caused by fluid pulsation, ensuring that the pressure and temperature variables of the input state equation can truly reflect the real-time state of the fluid; To ensure dynamic response accuracy, the filter window length of the above-mentioned moving average filtering algorithm is set to be greater than twice the fluid pulsation period and less than one-third of the transcritical phase transition induced boundary response delay constant. In a specific embodiment, the number of sampling points in the filter window is set to 10 to 20 consecutive sampling periods. This effectively eliminates the periodic high-frequency noise of the fluid while avoiding the introduction of significant signal phase lag, ensuring that the pressure and temperature variables in the input state equation can reflect the fluid state in real time and accurately.

[0045] The data processor uses the collected outlet pressure and temperature after deposition exposure to calculate the downstream leakage medium density using the real gas law. Then, it multiplies the actual volumetric flow rate of the downstream leakage condition by the downstream leakage medium density to calculate the mass leakage rate after deposition exposure. The corresponding conversion relationship is as follows: In the formula, The mass leakage rate after deposition exposure is expressed in kg / s. Density of the downstream leaked medium after deposition exposure, in units of ; The actual volumetric flow rate under downstream leakage conditions after deposition exposure, in units of ; Based on the collected inlet-side pressure, inlet-side temperature, outlet-side pressure, and outlet-side temperature after deposition exposure, the data processor locates the adjacent grid nodes of the current real-time test boundary value in the four-dimensional discrete grid matrix constructed by the calibration database. It then performs a multi-dimensional interpolation algorithm based on the inverse distance weights of the variables in each dimension or the multilinear spatial mapping rules to extract the equivalent flow capacity per unit area under the current test boundary. This extraction process also prohibits data extrapolation to the uncalibrated operating conditions. If the real-time test boundary exceeds the coverage of the discrete grid matrix of the calibration database, the data processor triggers an out-of-bounds shutdown command and locks the current extraction cycle of the effective flow section.

[0046] The data processor divides the mass leakage rate after deposition exposure by the equivalent flow capacity per unit area of ​​the currently matched sample to calculate the effective flow cross-section after deposition exposure. The corresponding cross-section extraction relationship is as follows: In the formula, The effective flow cross-section after deposition exposure, in units of ; The equivalent flow capacity per unit area corresponding to the sedimentary exposure state, in units of ; The calculated effective flow cross section is used to characterize the effective flow area of ​​the sealed micro-gap after the solid phase change deposit is desorbed or sublimated by the thermal boundary, so that it recovers to a state close to the actual structural damage. This data will be directly transmitted to the subsequent reliable evaluation unit as the core calculation basis for quantifying the phase change deposition shielding effect.

[0047] The reliable evaluation unit is used to combine the system measurement error source with the benchmark calibration error to synthesize the effective flow cross section comparison uncertainty. It compares and calculates the effective flow cross section after deposition exposure with the effective flow cross section under deposition shielding state plus the value of the effective flow cross section comparison uncertainty, extracts the true leakage characterization area, and generates a comprehensive evaluation result set.

[0048] The reliability assessment unit extracts the flow measurement error of the micro-flow detection device, the pressure measurement error of the pressure acquisition component, the temperature measurement error of the temperature acquisition component, and the calibration error of the calibration database through the system's data processor. Based on JJF 1059.1-2012 "Evaluation and Expression of Measurement Uncertainty," the system derives the standard uncertainty of the effective flow cross-section under deposition shielding and after deposition exposure by constructing the partial derivative transfer matrix of the effective flow cross-section calculation equation for each underlying input variable. Specifically, the measurement errors are obtained as follows: the flow measurement error of the micro-flow detection device, the pressure measurement error of the pressure acquisition component, and the temperature measurement error of the temperature acquisition component are determined based on the verification results, calibration results, or the measurement error range given by the equipment, and converted into the corresponding standard uncertainty according to the aforementioned metrological technical specifications. The calibration error of the calibration database is determined based on the reference flow area error of the calibration micro-orifice with a known reference flow area during the calibration process and the corresponding measurement error, and converted into the standard uncertainty of the equivalent flow capacity per unit area. Thus, the standard uncertainty of the actual volumetric flow rate is obtained. Pressure standard uncertainty Temperature standard uncertainty and the standard uncertainty of the equivalent flow capacity per unit area This serves as the input for subsequent uncertainty propagation calculations.

[0049] Taking the sediment-covered state as an example, based on Establish the first-order partial derivative sensitivity coefficient: the partial derivative with respect to the density of the downstream leaking medium is... The partial derivative with respect to the actual volumetric flow rate is The partial derivative of the equivalent flow capacity per unit area is Combining the various system measurement error sources and benchmark calibration errors, the standard uncertainty polynomial of the effective flow cross-section under the sedimentation shielding state is synthesized according to the variance propagation law as follows: The downstream leakage medium density is determined by the downstream outlet pressure and temperature using the aforementioned Span-Wagner equation of state. Therefore, the pressure and temperature measurement uncertainties propagate first to the medium density. Under deposition shielding conditions, the pressure and temperature acquisition components independently acquire the downstream outlet pressure and temperature, respectively, treating them as uncorrelated inputs. The standard uncertainty of the medium density is determined according to the following formula: In the formula, The standard uncertainty of the density of the downstream leaking medium under the deposition-masking condition; The standard uncertainty of downstream export-side pressure; The standard uncertainty of the downstream outlet temperature; This is the sensitivity coefficient of the medium density relative to the downstream outlet pressure under the current condition; This is the sensitivity coefficient of the medium density relative to the downstream outlet temperature under the current conditions, which is determined according to the aforementioned Span-Wagner equation of state under the current pressure and temperature conditions.

[0050] Among them, the standard uncertainty of the actual volumetric flow rate The measurement uncertainty originates from the micro-flow detection device; the standard uncertainty of the medium density. The standard uncertainty of pressure from the pressure acquisition component and the standard uncertainty of temperature from the temperature acquisition component are combined according to the aforementioned propagation relationship; the standard uncertainty of the equivalent flow capacity per unit area. The calibration uncertainties are derived from the calibration database. The uncertainties of the above input quantities are not directly added numerically, but are instead converted into the effective flow cross-section under the deposition-shielded state through the corresponding partial derivative sensitivity coefficients. The uncertainty contributions are calculated, and each converted uncertainty contribution has area dimensions. These are then synthesized according to the variance propagation law. Similarly, the standard uncertainty of the effective flow cross-section after deposition exposure is derived. ; Furthermore, the uncertainty of the effective flow cross section is synthesized, and the corresponding error synthesis relationship is as follows: In the formula, The uncertainty of the effective flow cross section is expressed in units of . ;k is the coverage factor preset by the test system based on the set confidence probability. The standard uncertainty of the effective flow cross section under deposition-shielded conditions is given in units of . ; The standard uncertainty of the effective flow cross section after deposition exposure is given in units of 1. .

[0051] Specifically, in this embodiment, during the calculation of the uncertainty of the effective flow cross section, the standard uncertainties of each input are synthesized through the aforementioned propagation relationship. When the synthesized result is characterized by an approximately normal distribution and uses a coverage probability of approximately 95%, the coverage factor k is set to 2. When the system uses other preset coverage probabilities, the value of k is set according to the corresponding coverage factor determination rules in JJF 1059.1-2012 "Evaluation and Expression of Measurement Uncertainty". Therefore, the value of k is determined by the preset coverage probability and the corresponding uncertainty distribution conditions, and is not arbitrarily adjusted based on the model of the valve being tested or real-time test data.

[0052] By introducing a standard uncertainty synthesis model for the instrument measurement and calibration process, the system constructs a numerical error tolerance boundary in the underlying algorithm. This comparative uncertainty serves as an objective basis for determining whether the change in the flow cross section is caused by the transformation of the actual structural flow state, thus avoiding misjudging the system's basic measurement noise as the shielding and elimination response of phase change deposits.

[0053] The reliable assessment unit uses the system's data processor to compare and calculate the effective flow cross section after sediment exposure with the sum of the effective flow cross section under sediment shading and the uncertainty of the effective flow cross section. When it is determined that the effective flow cross section after sediment exposure is greater than the sum of the latter two, the system concludes that the sediment exposure operation has actually released the flow channels that were shading by the phase change sediments.

[0054] Please see Figure 3 Under these comparative conditions, the reliability assessment unit calculates the self-blocking impact factor through the system's data processor. The corresponding factor calculation relationship is as follows: In the formula, This is a self-blocking influencing factor, which is a dimensionless parameter. The effective flow cross-section after deposition exposure, in units of The constant term, value 1, represents the baseline proportion state when no shading occurs in theory. The system can quantify the shading effect by subtracting the ratio of the effective flow cross section under the deposition shading state to the effective flow cross section after the deposition is exposed from value 1.

[0055] Under conditions where phase change deposition masking effect is clearly present, the data processor assigns the effective flow cross section after the deposition is exposed to the true leakage characterization area and fills this value into the comprehensive evaluation result set; this area data removes the masking effect of dry ice phase change deposits on potential sealing micro-damage channels, and is closer to the true effective flow area formed by the actual degradation of the valve sealing pair or packing structure under test. When the reliable assessment unit determines that the effective flow cross section after deposition exposure is less than or equal to the sum of the effective flow cross section under deposition shielding and the uncertainty of the effective flow cross section comparison, the system assumes that the difference in flow capacity before and after thermal boundary adjustment has not exceeded the measurement noise boundary. The data processor assigns the self-blocking influence factor to zero at this time and assigns the effective flow cross section under deposition shielding to the actual leakage characterization area, and then synchronously fills it into the comprehensive assessment result set.

[0056] The reliable assessment unit uses the system's data processor to collect calculation parameters from two complete operational stages: deposition shielding and deposition exposure. This generates a comprehensive assessment result set that includes the aforementioned core evaluation indicators. The corresponding structure of the assessment result set is as follows: In the formula, E represents the set of valve sealing reliability assessment results; The actual leakage area is represented by units of... ; The generated valve sealing reliability assessment result set completely preserves the original state data and masking correction data of supercritical carbon dioxide transcritical leakage under extreme operating conditions. This result set can be directly used to support the determination of the sealing decay state of the tested valve throughout its entire life cycle, completely eliminating the risk of assessment distortion caused by a single static pressure decay index.

[0057] In one specific embodiment, the supercritical carbon dioxide valve to be tested is installed in the test loop and kept closed, and the system is preset with a critical pressure for carbon dioxide. The pressure is 7.38 MPa and the critical temperature is preset. The pressure is 304.13K, with a preset triple point pressure. The pressure is 0.518 MPa; the phase change induction unit adjusts the pressure in the test chamber to make the upstream inlet side pressure... Reaching 9.0 MPa and upstream inlet side temperature Reaching 315.0K while controlling downstream export-side pressure. The pressure stabilized at 0.4 MPa, and the transcritical phase transition induced boundary was successfully constructed. Under the aforementioned phase transition induced boundary, the micro-flow detection device collected the actual volumetric flow rate of the downstream leakage under the deposition-masked state. for The temperature acquisition component obtains the downstream outlet temperature. The K value is 220.0 K; the data processor uses the real gas law to calculate the density of the downstream leaking medium at this point. for Multiplying the two yields the mass leakage rate under the deposition-shielded state. for ; Based on the current pressure and temperature test boundaries, the data processor linearly interpolates the equivalent flow capacity per unit area corresponding to the deposition shading state from the calibration database. for By dividing the mass leakage rate by the flow capacity, the system extracts the effective flow cross-section under the deposition-shielded state. for ; During the deposition exposure phase, the system sets a safe upper temperature limit based on the tolerance limit of the PTFE seal of the valve under test. The value is 393.15 K, and the reference temperature for solid-state deposition transformation corresponding to 0.4 MPa was found from the physical property database. Approximately 194.5K; the local thermal boundary adjustment device activates heating to control the wall temperature of the sealed area. It stabilizes at 293.15K, meeting the thermal boundary control requirements between the reference temperature and the safety upper limit.

[0058] After the deposition exposure stabilized, the pressure acquisition unit measured the downstream outlet side pressure. Maintaining a pressure of 0.4 MPa, the temperature acquisition component measured the downstream outlet temperature. The flow rate rebounded to 293.15 K; the micro-flow detection device re-collected the actual volumetric flow rate under downstream leakage conditions. Climb to The data processor recalculates the corresponding downstream leak medium density. for The mass leakage rate after deposition exposure was obtained. for ;

[0059] Based on the real-time test boundary after deposition exposure, the data processor extracts the corresponding equivalent flow capacity per unit area from the calibration database again. for The effective flow cross section after deposition exposure is extracted by dividing the new mass leakage rate by the flow capacity. for .

[0060] Based on the fundamental measurement errors of each sensor and the machining errors of the calibration orifice plate, the reliability evaluation unit, following the aforementioned inclusion factor determination rules (in this embodiment, the inclusion factor k is set to 2), calculates the effective flow cross-section comparison uncertainty. for The system executes a numerical comparison program to determine the effective flow cross-section after deposition exposure. Greater than the sum of the deposition shielding cross section and the comparison uncertainty It was confirmed that phase change deposition masking occurred during the testing process; Based on the above judgment results, the self-sealing influence factor calculated by the system is... The value is approximately 0.714, and cross-sectional data after deposition exposure are extracted as the true leakage characterization area. Its value is The final output is a valve sealing reliability assessment result set E containing all the above measured and calculated values, completing the anti-shading leakage assessment of the valve under this extreme operating condition.

[0061] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A valve sealing reliability testing and evaluation system under extreme operating conditions, characterized in that, include: The phase change induction unit is used to keep the valve under test closed, control the upstream inlet side to be in a supercritical state and the downstream outlet side pressure to be lower than the triple point pressure of carbon dioxide, and construct the transcritical phase change induction boundary for the precipitation of solid carbon dioxide phase change deposits. The cross-section extraction unit is used to obtain the actual volumetric flow rate and downstream leakage medium density under the transcritical phase change induced boundary, multiply them, convert them into the mass leakage rate under the deposition shielding state, and divide the mass leakage rate by the unit area equivalent flow capacity matched according to the current thermodynamic boundary to calculate the effective flow cross section under the deposition shielding state. The deposition exposure unit is used to apply a thermal boundary to cause the solid carbon dioxide phase change deposit to undergo a state transformation. It obtains the actual volumetric flow rate of the downstream leakage condition after deposition exposure and the density of the downstream leakage medium after deposition exposure, multiplies them, converts them into the mass leakage rate after deposition exposure, and divides the mass leakage rate by the equivalent flow capacity per unit area matched according to the current thermodynamic boundary to calculate the effective flow cross section after deposition exposure. The reliable evaluation unit is used to combine the system measurement error sources and the benchmark calibration error to synthesize the effective flow cross section comparison uncertainty. It compares and calculates the effective flow cross section after deposition exposure with the effective flow cross section under deposition shielding state plus the value of the effective flow cross section comparison uncertainty, extracts the true leakage characterization area, and generates a comprehensive evaluation result set.

2. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 1, characterized in that, In terms of system hardware architecture, it includes: Pressure regulating devices and upstream medium preheating devices for providing a fluid testing environment; local thermal boundary regulating devices for applying a locally controllable thermal boundary; pressure acquisition components, temperature acquisition components, and micro-flow detection devices for acquiring underlying state parameters; physical property databases and calibration databases for storing underlying parameters; and data processors for coordinating software and hardware instruction interaction and calculation.

3. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 1, characterized in that, The phase change induction unit keeps the valve under test closed, cuts off the valve drive source, and performs mechanical state locking. Mechanical locking maintains a constant contact pressure of the valve's internal sealing surfaces by limiting the valve with hardware or cutting off the control source, thus keeping the micro-geometry of the sealing gap unchanged.

4. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 2, characterized in that, The cross-section extraction unit obtains the density of the downstream leaking medium, including: The cross-section extraction unit receives the downstream outlet pressure collected by the pressure acquisition component and the downstream outlet temperature collected by the temperature acquisition component through the data processor, and performs nonlinear solution based on the Span-Wagner equation of state to extract the density of the downstream leaking medium.

5. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 2, characterized in that, include: The calibration database pre-stores the flow capacity benchmark value. The flow capacity benchmark value is the data obtained by array testing using calibration micropores with known benchmark flow area under the cross-arrangement boundary of different upstream inlet side pressure, upstream inlet side temperature, downstream outlet side pressure and downstream outlet side temperature, and constructed as a four-dimensional discrete grid matrix. The calibration micropores use standard flow-through plate with sufficient inner wall surface roughness to prevent irreversible adhesion and retention of transcritical solid carbon dioxide phase change deposits.

6. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 5, characterized in that, The data processor extracts the equivalent flow capacity per unit area from the calibration database, including: The section extraction unit uses a data processor to locate the adjacent grid nodes where the test boundary value of the current sampling period is located in the four-dimensional discrete grid matrix constructed by the calibration database, and executes a multi-dimensional interpolation algorithm to obtain the matching unit area equivalent flow capacity. If the real-time test boundary exceeds the coverage of the discrete grid matrix of the calibration database, the data processor triggers an out-of-bounds shutdown command and locks the current extraction cycle of the effective flow section, prohibiting data extrapolation to the uncalibrated operating range.

7. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 2, characterized in that, The deposition exposure unit applies a locally controllable thermal boundary through a local thermal boundary adjustment device, including: The deposition exposure unit uses a data processor to match the corresponding solid deposition conversion reference temperature from the phase equilibrium data in the physical property database based on the downstream outlet pressure collected by the pressure acquisition component. The data processor then controls the local thermal boundary adjustment device to ensure that the wall temperature of the sealed area is greater than the conversion reference temperature of the solid deposit under the current outlet pressure, but less than the upper limit of the safe temperature. The upper limit of the safe temperature is set as the highest allowable operating temperature rating of the component with the lowest temperature resistance inside the valve under test, minus the maximum positive absolute measurement error of the temperature acquisition component, and further minus the maximum transient control overshoot of the local thermal boundary adjustment device under step response.

8. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 2, characterized in that, The pressure acquisition component, temperature acquisition component, and micro-flow detection device establish serial communication with the data processor via an industrial bus. The data processor receives the sensing signals from each acquisition component and outputs the signals after performing a moving average filtering algorithm.

9. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 1, characterized in that, When the effective flow cross section after deposition exposure is determined to be less than or equal to the sum of the effective flow cross section under deposition shielding and the uncertainty of the effective flow cross section comparison, the reliable evaluation unit extracts the effective flow cross section under deposition shielding as the true leakage characterization area.

10. The valve sealing reliability testing and evaluation system under extreme operating conditions according to claim 1, characterized in that, The reliable assessment unit calculates the self-blocking influence factor by subtracting the ratio of the effective flow cross-section under the deposition shielding state to the effective flow cross-section after the deposition is exposed, based on numerical value 1. The comprehensive evaluation results set includes the mass leakage rate under the deposition shielding state, the mass leakage rate after deposition exposure, the effective flow cross section under the deposition shielding state, the effective flow cross section after deposition exposure, the uncertainty of the effective flow cross section comparison, the self-blocking influence factor, and the actual leakage characterization area.

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