Flow metering deviation correction method and system based on multi-component gas mixing change

Abstract

The invention relates to the technical field of flow measurement, in particular to a flow measurement deviation correction method and system based on multi-component gas mixing change. Comprising the following steps: acquiring actually measured sound velocity and temperature-pressure parameters by using an intelligent sensor; constructing a virtual component perception model, and inverting the instantaneous concentration ratio of each component in real time by using sound velocity and physical property association; the theoretical sound velocity reference value is dynamically corrected, the signal detection deviation is compensated, and the corrected operation volume flow is output; the component proportion is input into a state equation calculation engine, and a compression factor and real-time density are solved; finally, energy flow is output in combination with unit volume calorific value. Through second-level component inversion and physical property dynamic compensation, the problems of measurement response lag and precision reduction under the component fluctuation working condition are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow metering, in particular to a flow metering deviation correction method and system based on multi-component gas mixture change. BACKGROUND

[0002] In the fields of petrochemical industry, urban gas and hydrogen energy transmission and distribution, accurate measurement of multi-component gas flow is the core of trade settlement and process control. With the diversification of energy structure, the demand for measurement of natural gas mixed with hydrogen and high carbon dioxide content gas is increasing, which puts forward higher requirements for the component adaptability of flow meters.

[0003] The traditional flow metering system mainly relies on offline calibration under specific reference conditions, or obtains component data through online gas chromatographs for lag correction. The analysis period of online chromatographs is usually 3 to 5 minutes, which is difficult to capture the instantaneous component concentration fluctuation in industrial processes, resulting in a disconnection between the correction coefficient and real-time working conditions. The compressibility factor, isentropic exponent and dynamic viscosity of multi-component gas show high nonlinearity with component concentration fluctuation. When the components change, the internal sound speed calibration reference and instrument coefficient of traditional ultrasonic or vortex flow meters will produce significant deviation, causing serious systematic measurement error. Existing correction algorithms are mostly based on linear weighting of fixed components, and when dealing with high-pressure mixed gas rich in heavy hydrocarbons or non-hydrocarbon components, the thermodynamic equation often faces the problems of poor convergence and high prediction uncertainty.

[0004] The present application aims to solve the problems of response lag, measurement accuracy decline and inaccurate energy settlement of the flow metering system caused by insufficient real-time component detection and dramatic fluctuation of fluid physical property parameters under dynamic variable component working conditions of multi-component mixed gas.

[0005] To this end, a flow metering deviation correction method and system based on multi-component gas mixture change are proposed. SUMMARY

[0006] The present application aims to provide a flow metering deviation correction method and system based on multi-component gas mixture change, which solves the problems of response lag and accuracy decline of mixed gas metering under component fluctuation working conditions by real-time inversion of component proportion and dynamic compensation of physical property deviation.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: The flow metering deviation correction method based on multi-component gas mixture change comprises: real-time acquisition of the measured sound speed, operating temperature, operating pressure and operating volume flow of the mixed gas under the operating working condition by an intelligent sensor; A virtual component-aware model is constructed, and the measured sound velocity, operating temperature and operating pressure are input as characteristic variables, and the current isentropic index and current average molar mass of the mixed gas are obtained by real-time inversion using the physical correlation between the measured sound velocity, isentropic index and average molar mass of the mixed gas, and the instantaneous concentration ratio of each component in the mixed gas is calculated. The theoretical sound velocity calibration reference value inside the ultrasonic flowmeter is dynamically corrected according to the instantaneous concentration ratio, the ultrasonic signal detection deviation caused by the drastic fluctuation of the components is compensated, and the corrected operating volumetric flow rate is output. The instantaneous concentration ratio is input into a preset equation of state calculation engine, the operating temperature and the operating pressure are combined, the compression factor and the real-time density of the mixed gas are calculated in real time; The standard condition mass flow rate is calculated based on the real-time density and the corrected operating volumetric flow rate, and the energy flow rate of the mixed gas is output by combining the unit volume heat release calculated from the instantaneous concentration ratio.

[0008] Preferably, the specific steps of constructing the virtual component-aware model and calculating the instantaneous concentration ratio of each component include: establishing thermodynamic boundary constraints, retrieving the molecular weight, constant-pressure specific heat capacity and temperature-dependent function relationship of each single component according to a preset component list of the mixed gas, and establishing a mixed gas thermodynamic database in the virtual component-aware model; using the correlation between the measured sound velocity of the mixed gas and the thermodynamic state parameters, a thermodynamic equilibrium equation set composed of operating temperature, operating pressure, compression factor, isentropic index and average molar mass is established inside the virtual component-aware model; the measured sound velocity is used as the target convergence value, and the isentropic index and average molar mass are iteratively searched in the virtual component-aware model; when the absolute value of the difference between the model-calculated sound velocity and the measured sound velocity is less than a preset threshold, the current isentropic index and average molar mass of the mixed gas are determined; and the instantaneous concentration ratio of each preset component in the mixed gas is finally calculated by inverse vector operation according to the current isentropic index and current average molar mass, combined with the physical contribution coefficients of each single component.

[0009] Preferably, the process of obtaining the theoretical sound velocity calibration reference value is as follows: based on the instantaneous concentration ratio, the isentropic index and average molar mass corresponding to each component are retrieved from a preset thermodynamic component library; the ideal thermodynamic sound velocity under the current component state is calculated using a preset thermodynamic sound velocity formula combined with the operating temperature and operating pressure; the ideal thermodynamic sound velocity is used as the theoretical sound velocity calibration reference value for real-time comparison with the measured sound velocity to determine and compensate the acoustic signal transmission characteristic deviation caused by the change of the components.

[0010] Preferably, the specific step of outputting the corrected operating volumetric flow rate comprises: performing a real-time difference operation between the measured sound velocity and the reference value of the theoretical sound velocity to obtain a sound velocity deviation rate; determining the degree of absorption and attenuation of the ultrasonic signal by the mixed gas according to the sound velocity deviation rate, and correspondingly adjusting the signal gain level and zero-crossing detection threshold of the intelligent sensor to correct the propagation time measurement error caused by component fluctuation; recalculating the fluid flow rate in combination with the corrected propagation time, and substituting the measurement tube body expansion correction coefficient determined by the operating temperature and operating pressure to output the corrected operating volumetric flow rate.

[0011] Preferably, the specific steps of real-time calculating the compressibility factor and real-time density of the mixed gas comprise: determining the component characteristics of the mixed gas according to the instantaneous concentration ratio, and automatically calling a wide-range equation of state calculation engine based on Helmholtz free energy when the molar fraction of carbon dioxide exceeds a preset ratio; inputting the operating temperature, operating pressure, and instantaneous concentration ratio into the wide-range equation of state calculation engine, and obtaining the current compressibility factor of the mixed gas by establishing the partial derivative matrix of the intermolecular interaction force and performing real-time iterative solution; and calculating the real-time density of the mixed gas according to the measured gas law formula in combination with the operating temperature, operating pressure, current compressibility factor, and average molar mass calculated by weighting the instantaneous concentration ratio.

[0012] Preferably, the step of outputting the energy flow of the mixed gas comprises: using the instantaneous concentration ratio to search a preset component heat value database, and calculating the current unit volume heat release of the mixed gas according to the heat release of each single component under standard reference conditions; obtaining the standard condition pressure and standard condition temperature at the position of the intelligent sensor, and calculating the state conversion coefficient for converting the operating condition volume to standard condition volume in combination with the compressibility factor, operating pressure, and operating temperature; multiplying the corrected operating volumetric flow rate by the state conversion coefficient to obtain a standard condition volumetric flow rate, and then multiplying the standard condition volumetric flow rate by the current unit volume heat release to output the energy flow of the mixed gas in real time, thereby eliminating the heat value measurement deviation caused by component fluctuation.

[0013] The flow metering deviation correction system based on multi-component gas mixture change comprises: a data acquisition module: acquiring the measured sound velocity, operating temperature, operating pressure, and operating volumetric flow rate of the mixed gas under operating conditions in real time through an intelligent sensor; A component-aware module is configured to build a virtual component-aware model, input the measured sound velocity, operating temperature and operating pressure as characteristic variables, utilize the physical correlation between the measured sound velocity, isentropic index and average molar mass of the mixed gas, inversely calculate the current isentropic index and current average molar mass of the mixed gas in real time, and solve the instantaneous concentration ratio of each component in the mixed gas; A diagnostic correction module is configured to dynamically correct the theoretical sound velocity calibration reference value in the ultrasonic flowmeter according to the instantaneous concentration ratio, compensate for the ultrasonic signal detection deviation caused by the dramatic fluctuation of components, and output the corrected operating volumetric flow rate; A parameter calculation module is configured to input the instantaneous concentration ratio into a preset state equation calculation engine, combine the operating temperature and the operating pressure, and calculate the compression factor and real-time density of the mixed gas in real time; An energy output module is configured to calculate the standard condition mass flow rate based on the real-time density and the corrected operating volumetric flow rate, and output the energy flow rate of the mixed gas in combination with the unit volume heat release calculated from the instantaneous concentration ratio.

[0014] Compared with the prior art, the present application has the following advantages: 1. The present application realizes the second-level inversion of the component ratio of the mixed gas by building a virtual component-aware model and utilizing the measured sound velocity, operating temperature and pressure obtained by the intelligent sensor. Compared with the minute-level cycle limitation of the traditional online gas chromatography analysis, the present application effectively solves the component fluctuation lag problem caused by the multi-well rotation sampling or mixed gas injection. This high-frequency sensing mechanism ensures that the flow computer can accurately match the instantaneous physical state of the current fluid when calculating the correction coefficient.

[0015] 2. The present application dynamically corrects the theoretical sound velocity calibration reference value in the flowmeter by the isentropic index and molar mass inversely calculated in real time, effectively solves the detection error caused by the ultrasonic signal absorption attenuation of components such as carbon dioxide, and simultaneously automatically switches to the wide-range state equation calculation engine based on the Helmholtz free energy according to the component characteristics, so as to accurately solve the compression factor and real-time density. This deep coupling correction from the sensing layer signal to the thermodynamic property overcomes the disadvantage that the traditional single correction coefficient cannot adapt to the nonlinear change.

[0016] 3, The application deeply integrates the corrected operating volume flow, real-time density and unit volume heat release calculated based on component inversion, and constructs a full-range energy flow output system. The system can not only output accurate standard condition mass flow, but also automatically complete real-time dynamic correction of energy total calculation at the moment of component fluctuation, meeting the transformation requirement of high-value energy trade settlement to energy metering. Through this "mass-flow" integrated monitoring mode, the metering station can evolve into the core node of digital trade settlement, providing reliable technical support for new energy forms such as hydrogen energy mixed transportation. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 The method flowchart of the flow measurement deviation correction method based on multi-component gas mixture change provided by the application is shown in the figure. Fig. 2 The flowchart of the flow measurement deviation correction method based on multi-component gas mixture change provided by the application is shown in the figure. Fig. 3 The system structure diagram of the flow measurement deviation correction system based on multi-component gas mixture change provided by the application is shown in the figure. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0019] Embodiment one Please refer to Figs. 1 to 3 The application provides a flow measurement deviation correction method based on multi-component gas mixture change, and the technical solution is as follows: The flow measurement deviation correction method based on multi-component gas mixture change comprises the following steps: Real-time acquisition of measured sound velocity, operating temperature, operating pressure and operating volume flow of the mixed gas under operating conditions by an intelligent sensor; Construction of a virtual component sensing model, input of the measured sound velocity, operating temperature and operating pressure as characteristic variables, real-time inversion of the current isentropic exponent and current average molar mass of the mixed gas by using the physical correlation between the measured sound velocity, isentropic exponent and average molar mass of the mixed gas, and calculation of the instantaneous concentration ratio of each component in the mixed gas; Dynamic correction of the theoretical sound velocity calibration reference value in the ultrasonic flowmeter according to the instantaneous concentration ratio, compensation of the ultrasonic signal detection deviation caused by the severe fluctuation of components, and output of the corrected operating volume flow; inputting the instantaneous concentration ratio into a preset state equation calculation engine, combining the operating temperature and the operating pressure, and calculating a compressibility factor and a real-time density of the mixed gas in real time; calculating a standard condition mass flow based on the real-time density and the corrected operating volumetric flow, and combining the unit volume heat release calculated based on the instantaneous concentration ratio to output an energy flow of the mixed gas.

[0020] Further, the specific steps of acquiring the measured sound speed, operating temperature, operating pressure, and operating volumetric flow of the mixed gas under the operating condition in real time by the intelligent sensor and performing data preprocessing include: using a dynamic sliding average algorithm to perform denoising processing on the measured sound speed collected by the intelligent sensor, eliminating the sound speed mutation outliers caused by the trace liquid entrained in the mixed gas, and acquiring a stable measured sound speed; establishing a unified time stamp caching mechanism to perform millisecond-level time synchronization alignment on the asynchronously collected operating temperature, operating pressure, and measured sound speed, and ensuring that each group of characteristic variables corresponds to the physical state of the same fluid microelement; presetting a safety threshold range of each physical quantity, and monitoring whether the acquired operating pressure and operating temperature are within the convergence domain of the state equation calculation engine in real time; if it is detected that the parameters are out of limits, triggering a component locking mechanism and calling a preset standard contract component for replacement calculation; calculating the volume expansion coefficient of the intelligent sensor measurement tube in real time according to the acquired operating temperature and operating pressure, and correcting the geometric size deviation of the sound path length and the measurement tube cross-sectional area caused by environmental changes.

[0021] Specifically, the dynamic sliding average algorithm uses an adaptive window based on flow rate fluctuation, and the window length N is automatically reduced as the standard deviation of the measured sound speed increases, to balance the denoising effect and dynamic response sensitivity. The convergence domain is set according to the physical effective boundary of the wide-range state equation used, for example, for natural gas components, the upper limit of the pressure is preset to 70 MPa, and the temperature interval is set to 143 K to 673 K; when the monitored value exceeds this boundary, the system automatically retrieves the contract component mole percentage stored in the non-volatile memory for replacement, and records an audit tracking log. The calculation model of the volume expansion coefficient and takes into account the thermal expansion coefficient and the elastic modulus of the tube material, and corrects the sound path length L and the flow passage cross-sectional area A to ensure that the deviation correction accuracy of the geometric parameters is better than 0.01% under high temperature and high pressure conditions.

[0022] The embodiment improves the reliability and robustness of the measurement data under complex working conditions through data preprocessing and dynamic geometric compensation. The adaptive moving average algorithm can effectively eliminate the singular values of the signal caused by impurities such as liquid droplets, and the millisecond-level time synchronization ensures the strict correspondence of multi-dimensional characteristic variables in the physical state of the fluid micro-element, providing accurate input for virtual component sensing. At the same time, through real-time monitoring of the convergence domain of the state equation and the component locking emergency mechanism, the risk of calculation failure caused by model divergence under extreme temperature and pressure environment is effectively avoided, and the legality and traceability of the measurement process are ensured through audit tracking.

[0023] Further, the specific steps of constructing the virtual component sensing model and solving the instantaneous concentration ratio of each component include: establishing thermodynamic boundary constraints, according to the preset component list of the mixed gas, calling the molecular weight, constant-pressure specific heat capacity and function relationship changing with temperature of each single component, and establishing a mixed gas thermodynamic basic database in the virtual component sensing model; using the correlation characteristics of the measured sound speed and the thermodynamic state parameters of the mixed gas, a thermodynamic equilibrium equation group consisting of operating temperature, operating pressure, compression factor, isentropic exponent and average molar mass is established in the virtual component sensing model; the measured sound speed is taken as the target convergence value, and the isentropic exponent and average molar mass are iteratively searched in the virtual component sensing model; when the absolute value of the difference between the model calculated sound speed and the measured sound speed is less than a preset threshold value, the current isentropic exponent and average molar mass of the mixed gas are determined; according to the current isentropic exponent and current average molar mass, combined with the physical contribution coefficient of each single component, inverse vector operation is performed to finally solve the instantaneous concentration ratio of each preset component in the mixed gas.

[0024] In the inverse vector operation, the physical contribution coefficient is the reference sound speed contribution item of each single component i under the current operating temperature T and pressure P . The coefficient is obtained by calling the partial molar properties of each component in the thermodynamic basic database, and reflects the sensitivity of the total sound speed of the mixed gas to the small change of the component concentration.

[0025] Specifically, the thermodynamic equilibrium equation group is constructed based on the gas state equation and the sound speed basic definition formula , wherein is the isentropic exponent affected by the component heat capacity, is the average molar mass of the mixed gas. The iterative search adopts the Newton-Raphson method, and the preset threshold value is set to 0.05% of the measured sound speed to ensure the rapid convergence of the thermodynamic equilibrium state. The inverse vector operation is realized by constructing a component contribution sensitivity matrix, and the least square method is used to solve the characteristic vector of the molar composition of each component in the multi-dimensional constraint space In the solving process, the physical constraint conditions of the total sum of components being 1 and the non-negative concentration of each component are introduced, and the optimal processing of the objective function is carried out through the Lagrange multiplier method, so as to ensure that the instantaneous concentration ratio of each component calculated is in accordance with the physical actuality.

[0026] The thermodynamic equilibrium equation set is non-ideal corrected by introducing the actual gas state equation, and the measured sound velocity c is expressed as a functional about pressure P, temperature T and molar composition vector In the solving process, the characteristic background component of the mixed gas (such as the standard composition of natural gas) is preset to reduce the dimension of the variable to be solved, and the constraint condition and the polynomial correlation of the heat capacity fluctuation of each component are introduced. The iterative search adopts an optimization algorithm with global convergence, takes the residual error between the measured sound velocity and the model calculated sound velocity as the objective function, and combines the Lagrange multiplier method to ensure that the instantaneous concentration ratio output is in accordance with the physical law of mass conservation.

[0027] The logic operator of the reverse vector operation adopts the least square iterative algorithm based on the Jacobian matrix. In the operation process, the difference between the measured sound velocity and the model prediction value is taken as the objective function, and an optimal molar fraction vector is found by gradient search in the multi-dimensional component space. This process strictly constrains the sum of the proportions of each component to be 1 and the concentration value to be non-negative, ensuring that the inversion result not only tends to converge in mathematics, but also meets the physical logic of mass conservation.

[0028] For specific application scenarios (such as natural gas long-distance pipelines), the heavy hydrocarbon components above are set as fixed proportions based on historical data, and only the components such as , , and with large fluctuations are taken as active variables to be inverted. By reducing the number of variables to be solved, the original underdetermined equation is converted into a determined or overdetermined equation, thereby significantly improving the convergence speed and anti-interference ability of the algorithm under dynamic conditions.

[0029] The scheme introduces the actual gas state equation to non-ideally correct the sound velocity inversion logic, effectively eliminates the principle deviation caused by the ideal gas model under high pressure conditions, and ensures the physical accuracy of the component calculation. The multi-dimensional constraint optimization algorithm is used to solve the underdetermined equation problem in the solving process, and the background component characteristics and mass conservation constraint are combined to realize the real-time sensing of components at the level of seconds without a hardware chromatograph. This mechanism not only significantly improves the dynamic response speed of the system to the sharp fluctuations of components, but also ensures the global convergence of the iterative calculation in the wide range of operating intervals and the robustness of the measurement results.

[0030] Further, the process of obtaining the theoretical sound speed calibration reference value is: based on the instantaneous concentration ratio, retrieving a preset thermodynamic component library to obtain the corresponding isentropic index and average molar mass of each component; combining the operating temperature and operating pressure, and using a preset thermodynamic sound speed formula to calculate the ideal thermodynamic sound speed under the current component state; taking the ideal thermodynamic sound speed as the theoretical sound speed calibration reference value, which is used for real-time comparison with the measured sound speed to determine and compensate the deviation of the acoustic signal transmission characteristics caused by component changes.

[0031] Specifically, the calculation of the theoretical sound speed calibration reference value not only depends on the basic physical parameters of the components, but also introduces a non-ideal correction logic based on the actual gas state equation. The thermodynamic sound speed calculation process compensates the ideal sound speed for non-idealities by introducing a compression factor and its partial derivative term determined by the operating temperature, operating pressure, and instantaneous concentration ratio. The determination process sets a dynamic deviation threshold, usually taking a few thousandths of the measured sound speed as the determination boundary. When the residual error between the measured sound speed and the theoretical sound speed exceeds the threshold, the system adjusts the ultrasonic wave emission intensity, signal amplification multiple, and zero-crossing detection time window of the intelligent sensor through a closed-loop feedback function. Through the above description of non-ideal characteristics and closed-loop feedback of the signal layer, it is ensured that when the physical properties of multi-component mixed gas fluctuate, the calibration reference value can truly reflect the thermodynamic boundary of the fluid under actual pressure, thereby realizing accurate correction of the acoustic transmission time error.

[0032] By introducing a non-ideal correction logic based on the actual gas state equation, the embodiment solves the prediction deviation of the traditional ideal sound speed model under high-pressure variable component conditions, significantly improving the physical accuracy of the theoretical sound speed calibration reference value. Combined with dynamic residual determination and signal gain closed-loop compensation technology, the system can real-time perceive and eliminate the ultrasonic signal attenuation and detection position shift caused by the dramatic fluctuation of components, effectively reducing the systematic error of the flowmeter in complex mixed media. This calibration mechanism not only enhances the self-diagnosis capability of the intelligent sensor, but also guarantees the long-term stability of flow measurement and the accuracy of trade settlement in the new energy transportation scene of hydrogen-doped natural gas and the like.

[0033] Further, the specific steps of outputting the corrected operating volume flow rate include: performing real-time difference operation on the measured sound speed and the theoretical sound speed calibration reference value to obtain a sound speed deviation rate; determining the degree of ultrasonic signal absorption and attenuation of the mixed gas according to the sound speed deviation rate, and correspondingly adjusting the signal gain level and zero-crossing detection threshold of the intelligent sensor to correct the propagation time measurement error caused by component fluctuation; combining the corrected propagation time to recalculate the fluid flow rate, and substituting it into the measurement tube volume expansion correction coefficient determined by the operating temperature and operating pressure to output the corrected operating volume flow rate.

[0034] Table 1: Sound velocity-attenuation mapping table ; Specifically, the determination process is realized by a preset sound velocity-attenuation mapping table, as shown in Table 1, which records the nonlinear correspondence between the change in sound velocity of a typical component (such as carbon dioxide) at different concentrations and the ultrasonic signal energy absorption value. The adjustment of the signal gain level of the intelligent sensor adopts a closed-loop feedback mechanism. When the sound velocity deviation rate exceeds the set threshold, the system dynamically increases the receiving gain in a step-by-step manner according to the deviation sign and magnitude, and simultaneously translates the time window triggered by the zero-crossing point in proportion to compensate for the phase shift caused by the distortion of the signal front edge. The measurement tube body expansion correction coefficient is determined according to the linear expansion coefficient and elastic modulus of the tube body material. The calculation model considers the axial expansion caused by the operating temperature and the radial expansion caused by the operating pressure, and eliminates the system error caused by the change of the geometric size of the measurement tube with the working condition in real time by correcting the sound path length L and the sound channel installation angle .

[0035] The above mapping data is obtained through the following experimental steps: first, under standard reference conditions, a single known concentration of interfering component is used to establish a baseline acoustic envelope model; then, by continuously adjusting the component concentration, the degree of distortion of the signal envelope caused by molecular vibration relaxation is recorded, and the gain compensation amount and the translation coefficient of the time window are determined in reverse by taking the zero-crossing point detection no longer phase misregistration as the target.

[0036] Due to the risk of "sound velocity degeneracy" in which different component configurations may produce the same sound velocity (for example, increasing heavy hydrocarbons causes the sound velocity to decrease while increasing hydrogen causes the sound velocity to increase), the present scheme introduces ultrasonic signal intensity attenuation as an auxiliary constraint condition in the virtual component perception model. By intersecting the sound velocity contour and the attenuation contour on the component plane, the unique determination of the instantaneous proportion of three or more components is realized by using the sharp attenuation characteristics of sound energy caused by the molecular vibration relaxation of components such as carbon dioxide, eliminating the non-uniqueness of single physical quantity inversion.

[0037] In view of the fact that the sound velocity is not a direct measurement value but is derived from the propagation time, in order to avoid the risk of causal inversion and positive feedback oscillation in the correction logic, the system adopts a time decoupling strategy. Specifically, the system uses the stable component distribution obtained by inversion at time k-1 to predict the physical reference value at time k, and performs real-time signal compensation at time k. At the same time, an amplitude limiting logic of compensation amount is set in the diagnosis and correction module to prevent the measurement from fluctuating sharply due to inversion jump through damping processing, ensuring the causal stability of the flow output.

[0038] The embodiment effectively solves the problem of ultrasonic signal quality degradation caused by high-absorption components in multi-component gas by constructing a coupling compensation mechanism of acoustic deviation and signal transmission characteristics, ensuring high precision of time-of-flight measurement under complex working conditions. Combined with dynamic geometric correction based on material mechanical properties, the system eliminates additional deviations caused by measurement tube size changes in high temperature and high pressure environments, achieving comprehensive precision protection from electronic signal processing to mechanical structure compensation. This technology not only significantly improves the operational stability of the flowmeter when the component fluctuates dramatically, but also pushes the volumetric measurement accuracy of multi-component mixed gas to a new height of industrial standards.

[0039] Further, the specific steps of calculating the compression factor and the real-time density of the mixed gas in real time include: According to the instantaneous concentration ratio, the component characteristics of the mixed gas are determined. When the carbon dioxide mole fraction exceeds a predetermined ratio, a wide-range equation of state calculation engine based on the Helmholtz free energy is automatically called. The operating temperature, operating pressure, and the instantaneous concentration ratio are input into the wide-range equation of state calculation engine. By establishing the partial derivative matrix of the intermolecular forces of each component, the current compression factor of the mixed gas is obtained by real-time iterative solution. The real-time density of the mixed gas is calculated according to the measured gas law formula, combining the operating temperature, operating pressure, current compression factor, and average molar mass calculated by the instantaneous concentration ratio.

[0040] Specifically, the predetermined ratio is set to 10% of the carbon dioxide mole fraction. When the concentration exceeds this threshold or the ethane mole fraction exceeds 8%, the calculation engine is switched from the traditional AGA8 mode to the GERG-2008 calculation engine based on the Helmholtz free energy. When establishing the partial derivative matrix, the wide-range equation of state calculation engine first calculates the reduced temperature and reduced density of the mixed gas using the mixing rule, and constructs a second-order partial derivative array about the ideal gas term and the residual term. The real-time iterative solution process uses the Newton iteration method, with a preset initial compression factor of 1.0 as the starting point and an iterative convergence accuracy of In each iteration, the compression factor value is updated by calculating the second-order partial derivative of the mixture residual free energy with respect to the density. In the real-time density calculation process, the average molar mass is obtained by the scalar product sum of the mole fraction of each component and the corresponding molecular weight, ensuring that the density output can reflect the non-ideal volume convergence effect caused by intermolecular interaction in real time.

[0041] The embodiment introduces a calculation engine based on component characteristics to automatically switch the mechanism, solves the problems of calculation divergence and precision degradation of the traditional model in the environment of high concentration carbon dioxide or heavy hydrocarbon components, and ensures the wide-range applicability of the mixed gas property prediction. The technology not only significantly improves the thermodynamic stability of the flowmeter in the complex mixed gas metering scene, but also provides a property benchmark for subsequent standard condition mass conversion and energy flow settlement.

[0042] Further, the step of outputting the energy flow of the mixed gas includes: using the instantaneous concentration ratio to retrieve a preset component heat value database, and calculating the current unit volume heat release of the mixed gas according to the heat release of each single component under standard reference conditions; obtaining the standard condition pressure and standard condition temperature at the position of the intelligent sensor, and combining the compression factor, operating pressure and operating temperature to calculate a state conversion coefficient for converting the operating condition volume to the standard condition volume; multiplying the corrected operating volume flow by the state conversion coefficient to obtain the standard condition volume flow, and then multiplying the standard condition volume flow by the current unit volume heat release to output the energy flow of the mixed gas in real time, thereby eliminating the heat value metering deviation caused by component fluctuations.

[0043] Specifically, the calculation of the unit volume heat release is performed according to the GB / T 11062 standard, the high heat release is used as the assignment reference, and the combustion reference temperature and the metering reference temperature are preset to be consistent. The calculation model of the state conversion coefficient comprehensively considers the correction of the ideal gas law and the difference between the measured gas compression characteristics, and is calculated by correlating the real-time obtained standard condition pressure , standard condition temperature and standard condition compression factor calculated by the state equation, with the pressure , temperature and compression factor under the operating condition. During the output of the energy flow, the system monitors the contribution rate of the component ratio to the heat release in real time, ensures the synchronous adjustment of the heat release assignment and the state conversion coefficient in the moment of component fluctuation, and thus realizes the high unification of the energy settlement result and the real heat value of the transported resources.

[0044] The embodiment realizes the accurate leap from the operating condition volume metering to the real-time energy metering by integrating the dynamic component analysis and the precise thermodynamic conversion model, and fundamentally eliminates the settlement error caused by the heat value fluctuation of the multi-component gas. By using the synchronous correction of the state conversion coefficient and the heat value library retrieval technology, the physical state under different reference conditions can be automatically matched, and the trade settlement result has high legal compliance and data traceability.

[0045] The embodiment significantly improves the real-time performance and accuracy of multi-component gas metering under dynamic working conditions by constructing a deep coupling system of intelligent sensors and virtual component sensing models. The measured sound velocity is used to real-time inversion of component proportion, which effectively overcomes the problem of disconnection of correction coefficient caused by the minute-level detection lag of online chromatograph. At the same time, through the dynamic correction of instantaneous component concentration to the detection deviation of acoustic signal and thermodynamic property parameter, the nonlinear interference of component fluctuation on flow rate measurement and compression factor calculation is eliminated. The scheme not only realizes the accurate leap from working volume to standard condition mass and energy flow, ensures the uncertainty control at the leading level of industry, but also provides core technical support for the digital settlement of complex mixed gas such as hydrogen energy blending and high-carbon capture.

[0046] Embodiment two Please refer to Fig. 3 The application provides a flow metering deviation correction system based on multi-component gas mixture change, and the technical scheme is as follows: The flow metering deviation correction system based on multi-component gas mixture change, as shown in Fig. 3 , comprises: A data acquisition module acquires the measured sound velocity, operating temperature, operating pressure and operating volume flow of the mixed gas under the running working condition through intelligent sensors in real time; A component sensing module constructs a virtual component sensing model, inputs the measured sound velocity, operating temperature and operating pressure as characteristic variables, uses the physical correlation between the measured sound velocity, isentropic index and average molar mass of the mixed gas, real-time inversion of the current isentropic index and current average molar mass of the mixed gas, and calculates the instantaneous concentration proportion of each component in the mixed gas; A diagnosis correction module dynamically corrects the theoretical sound speed calibration reference value in the ultrasonic flowmeter according to the instantaneous concentration proportion, compensates for the ultrasonic signal detection deviation caused by the dramatic fluctuation of components, and outputs the corrected operating volume flow; A parameter calculation module inputs the instantaneous concentration proportion into a preset state equation calculation engine, combines the operating temperature and the operating pressure, and real-time calculates the compression factor and real-time density of the mixed gas; An energy output module calculates the standard condition mass flow based on the real-time density and the corrected operating volume flow, and outputs the energy flow of the mixed gas in combination with the unit volume heat release calculated from the instantaneous concentration proportion.

[0047] The embodiment relates to a deviation correction system applied to a hydrogen-doped natural gas trade settlement point. In this scenario, the injection proportion of hydrogen is affected by the fluctuation of upstream electrolytic water hydrogen production, and the sound velocity, calorific value and compression characteristics of the medium are in dynamic change.

[0048] The data acquisition module obtains the measured sound velocity and operating volume flow rate of the hydrogen-doped mixed gas under an operating pressure of 5.0 MPa and an operating temperature of 288.15 K through an ultrasonic intelligent sensor arranged on the trunk pipeline. The module has a built-in dynamic sliding average algorithm, which can quickly filter the singular values of the sound velocity caused by fluid disturbance in the initial stage of hydrogen doping, and through a millisecond-level time stamp synchronization mechanism, ensures that the temperature and pressure parameters and the sound velocity data are accurately locked on the same fluid microelement.

[0049] The component-aware module receives the characteristic variables from the acquisition module, and constructs a virtual component-aware model for hydrogen-doped natural gas. The module calls the thermodynamic function relationship of hydrogen and methane and other typical components in the database, and performs Newton iteration in the internal thermodynamic balance equation group with the measured sound velocity as the convergence target. When the calculation residual is less than 0.05%, the system successfully inverts the change result of the hydrogen concentration from 3% to 10% instantaneous fluctuation, realizing real-time component monitoring without a hardware chromatograph.

[0050] The diagnosis correction module dynamically corrects the theoretical sound speed calibration reference value in the ultrasonic flowmeter by using the 10% hydrogen concentration ratio inverted by the awareness module. Since the increase of hydrogen content will change the absorption characteristics of the sound wave signal, the module compares the measured sound velocity with the corrected theoretical reference value, automatically adjusts the signal gain level and zero-crossing detection threshold of the sensor, corrects the propagation time measurement error caused by signal phase shift, and inputs the pipe body expansion correction coefficient to output accurate operating volume flow rate.

[0051] The parameter calculation module identifies that the gas non-ideality is significant under the current operating condition according to the inverted component characteristics, and automatically calls the GERG-2008 wide-range equation of state calculation engine based on the Helmholtz free energy. The module establishes the partial derivative matrix of intermolecular interaction force, accurately iterates the compression factor and real-time density under the condition of 10% hydrogen doping, and eliminates the calculation deviation of the traditional AGA8 model under the hydrogen fluctuation condition.

[0052] The flow and energy output module converts the volume flow rate into standard condition mass flow rate based on the accurate real-time density. At the same time, the module dynamically retrieves the heat value database according to the 10% hydrogen proportion, weightedly calculates the unit volume heat release of the current mixed gas, and finally outputs the accurate energy flow combined with the state conversion coefficient. The system ensures that the trade settlement result can reflect the real heat value of the transported resources in real time during the fluctuation of the hydrogen doping proportion, and guarantees the fairness of energy transaction.

[0053] The modular collaborative scheme of the system solves the problems of component detection lag and property deviation fluctuation under the hydrogen doping condition, and realizes real-time energy metering output with high precision and high reliability.

[0054] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A flow metering deviation correction method based on multi-component gas mixing variation, characterized in that, include: The system uses intelligent sensors to obtain real-time measurements of the sound velocity, operating temperature, operating pressure, and operating volume flow rate of the mixed gas under operating conditions. A virtual component sensing model is constructed, and the measured sound velocity, operating temperature and operating pressure are used as feature variables as inputs. By utilizing the physical correlation between the measured sound velocity, isentropic index and average molar mass of the mixed gas, the current isentropic index and current average molar mass of the mixed gas are obtained in real time, and the instantaneous concentration ratio of each component in the mixed gas is calculated. The theoretical sound velocity calibration benchmark value inside the ultrasonic flow meter is dynamically corrected based on the instantaneous concentration ratio to compensate for the ultrasonic signal detection deviation caused by drastic fluctuations in composition, and the corrected operating volume flow rate is output. The instantaneous concentration ratio is input into a preset state equation calculation engine, and the compressibility factor and real-time density of the mixed gas are calculated in real time by combining the operating temperature and the operating pressure. The standard condition mass flow rate is calculated based on the real-time density and the corrected operating volume flow rate, and the energy flow rate of the mixed gas is output by combining the calorific value per unit volume calculated from the instantaneous concentration ratio.

2. The flow metering deviation correction method based on multi-component gas mixing variation according to claim 1, characterized in that, The specific steps for constructing the virtual component sensing model and calculating the instantaneous concentration ratio of each component include: establishing thermodynamic boundary constraints; retrieving the molecular weight, specific heat capacity at constant pressure, and functional relationship with temperature of each individual component based on a preset list of mixed gas components, and establishing a basic thermodynamic database of the mixed gas in the virtual component sensing model; utilizing the correlation between the measured sound velocity and thermodynamic state parameters of the mixed gas, establishing a set of thermodynamic equilibrium equations consisting of operating temperature, operating pressure, compressibility factor, isentropic index, and average molar mass within the virtual component sensing model; using the measured sound velocity as the target convergence value, iteratively searching for the isentropic index and average molar mass in the virtual component sensing model; determining the current isentropic index and average molar mass of the mixed gas when the absolute value of the difference between the model-calculated sound velocity and the measured sound velocity is less than a preset threshold; and performing inverse vector operations based on the current isentropic index and current average molar mass, combined with the physical contribution coefficient of each individual component, to finally calculate the instantaneous concentration ratio of each preset component in the mixed gas.

3. The flow metering deviation correction method based on multi-component gas mixing variation according to claim 1, characterized in that, The process of obtaining the theoretical sound velocity verification benchmark value is as follows: based on the instantaneous concentration ratio, a preset thermodynamic component library is searched to obtain the isentropic index and average molar mass of each component; Combining the operating temperature and operating pressure, the ideal thermodynamic velocity under the current component state is calculated using a preset thermodynamic velocity formula; The ideal thermodynamic sound velocity is used as the theoretical sound velocity verification benchmark value, which is used to compare with the measured sound velocity in real time to determine and compensate for the deviation of acoustic signal transmission characteristics caused by component changes.

4. The flow metering deviation correction method based on multi-component gas mixing variation according to claim 1, characterized in that, The specific steps for outputting the corrected operating volumetric flow rate include: performing real-time difference calculation between the measured sound velocity and the theoretical sound velocity verification benchmark value to obtain the sound velocity deviation rate; determining the degree of absorption and attenuation of the ultrasonic signal by the mixed gas based on the sound velocity deviation rate, and adjusting the signal gain level and zero-crossing detection threshold of the smart sensor accordingly to correct the propagation time measurement error caused by component fluctuations; recalculating the fluid velocity based on the corrected propagation time, and substituting the measurement tube expansion correction coefficient determined by the operating temperature and operating pressure to output the corrected operating volumetric flow rate.

5. The flow metering deviation correction method based on multi-component gas mixing variation according to claim 1, characterized in that: The steps for calculating the compressibility factor and real-time density of the gas mixture include: determining the component characteristics of the gas mixture based on the instantaneous concentration ratio; automatically invoking a wide-range equation of state calculation engine based on Helmholtz free energy when the carbon dioxide mole fraction exceeds a preset ratio; inputting the operating temperature, operating pressure, and instantaneous concentration ratio into the wide-range equation of state calculation engine, establishing a partial derivative matrix of intermolecular interaction forces of each component, and iteratively solving in real time to obtain the current compressibility factor of the gas mixture; and combining the operating temperature, operating pressure, current compressibility factor, and average molar mass calculated by weighting the instantaneous concentration ratio, calculating the real-time density of the gas mixture according to the measured gas law formula.

6. The flow metering deviation correction method based on multi-component gas mixing variation according to claim 1, characterized in that: The steps for outputting the energy flow rate of the mixed gas include: using the instantaneous concentration ratio, searching a preset component calorific value database; calculating the current calorific value per unit volume of the mixed gas based on the calorific value of each elemental component under standard reference conditions; obtaining the standard condition pressure and standard condition temperature at the location of the smart sensor, and calculating the state conversion coefficient for converting the operating condition volume to the standard condition volume by combining the compressibility factor, operating pressure, and operating temperature; multiplying the corrected operating volume flow rate by the state conversion coefficient to obtain the standard condition volume flow rate; and then multiplying the standard condition volume flow rate by the current calorific value per unit volume to output the energy flow rate of the mixed gas in real time, thereby eliminating the calorific value measurement deviation caused by component fluctuations.

7. A flow metering deviation correction system based on multi-component gas mixing variation, characterized in that, include: Data acquisition module: Real-time acquisition of the measured sound velocity, operating temperature, operating pressure, and operating volumetric flow rate of the mixed gas under operating conditions through intelligent sensors; Component sensing module: Constructs a virtual component sensing model, takes the measured sound velocity, operating temperature and operating pressure as feature variables as input, and uses the physical relationship between the measured sound velocity, isentropic index and average molar mass of the mixed gas to obtain the current isentropic index and current average molar mass of the mixed gas in real time, and calculates the instantaneous concentration ratio of each component in the mixed gas. Diagnostic correction module: dynamically corrects the theoretical sound velocity calibration benchmark value inside the ultrasonic flow meter according to the instantaneous concentration ratio, compensates for the ultrasonic signal detection deviation caused by drastic fluctuations in composition, and outputs the corrected operating volume flow rate; Parameter calculation module: Input the instantaneous concentration ratio into the preset state equation calculation engine, and calculate the compressibility factor and real-time density of the mixed gas in real time by combining the operating temperature and the operating pressure; Energy output module: Calculates standard condition mass flow rate based on the real-time density and the corrected operating volume flow rate, and outputs the energy flow rate of the mixed gas by combining the calorific value per unit volume calculated from the instantaneous concentration ratio.

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