A gas-liquid two-phase flow measurement method and device based on combination of differential pressure type venturi flowmeter and vortex flowmeter

Abstract

The application discloses a gas-liquid two-phase flow measurement method and device based on a differential pressure Venturi flowmeter combined with a vortex flowmeter, relates to the technical field of gas-liquid two-phase flow measurement, collects a differential pressure signal transient change curve of a throat area of the differential pressure Venturi flowmeter, synchronously collects a temperature fluctuation amplitude of a corresponding section, extracts compressed bubble cluster characteristic data according to a preset differential pressure growth rate threshold and a temperature offset amplitude interval; the compressed bubble cluster characteristic data is subjected to frequency domain splitting, a high-frequency disturbance component in the differential pressure signal is extracted, the high-frequency disturbance component is processed according to a preset amplitude attenuation coefficient, and a differential pressure signal sequence after suppression is constructed. Through the cooperative analysis of the pressure, temperature and flow variation characteristics of the gas-liquid two-phase flow, the abnormal disturbance caused by the compression of the bubble cluster is recognized, meanwhile, the gas phase flow output value is dynamically compensated according to the compression behavior, the flow underestimation deviation caused by the bubble compression is reduced, and the measurement accuracy and stability of the gas-liquid two-phase flow are improved.

Description

Technical Field

[0001] This application relates to the field of gas-liquid two-phase flow measurement technology, specifically to a gas-liquid two-phase flow measurement method and device based on a combination of a differential pressure venturi flow meter and a vortex flow meter. Background Technology

[0002] The combined differential pressure Venturi flowmeter and vortex flowmeter for gas-liquid two-phase flow measurement specifically refers to the following: the gas-liquid two-phase flow is first mixed and rectified, so that the original non-uniformly distributed two-phase flow is transformed into a relatively uniform and stable equivalent single fluid state after passing through a phase stabilizer. Then, under this stable flow condition, the differential pressure Venturi flowmeter is used to detect the pressure difference generated by the fluid at the throttling device. In conjunction with differential pressure sensors, temperature sensors, and pressure sensors arranged at the throat of the Venturi tube and the upstream straight pipe section, the pressure difference signal, fluid temperature parameters, and pipeline pressure parameters are obtained respectively, thereby reflecting the density and flow characteristics of the mixed fluid.

[0003] Meanwhile, a vortex flow meter is installed downstream of the Venturi flow meter to directly measure the volumetric flow rate of the overall gas-liquid two-phase flow after mixing. Finally, the signal acquisition and data processing unit synchronously receives the volumetric flow rate signals output by the two types of flow meters, as well as differential pressure, temperature, and pressure information via cable. Based on the preset gas-liquid two-phase flow mathematical model, the equivalent physical property parameters of the mixed fluid are decoupled and calculated, and then the gas phase flow rate and liquid phase flow rate are obtained separately, so as to realize the accurate measurement and separation characterization of the flow rates of each phase in the gas-liquid two-phase flow.

[0004] When the gas-liquid two-phase flow passes through the mixed-phase stabilizer and enters the throat region of the venturi tube, a large number of tiny bubbles in the fluid rapidly aggregate under the influence of local flow field shearing and velocity gradient, forming a transiently high-concentration bubble agglomeration structure. When this bubble agglomeration enters the high-pressure zone of the throat, its volume is drastically compressed over a short distance, causing a false surge in local fluid density. At this time, the pressure difference signal between the throat and the contraction section acquired by the differential pressure sensor will be significantly amplified and deviate from the normal range that actually reflects the overall flow characteristics. When the signal acquisition and data processing unit receives this abnormal differential pressure signal and substitutes it into the preset mathematical model for calculation, it will misjudge this local transient density anomaly as a sign of a significant increase in the liquid phase ratio, thus causing a systematic deviation in the gas-liquid phase separation calculation results and severely underestimating the output gas phase flow rate.

[0005] Based on this, if the misjudgment result is involved in the process control logic, it will further lead to incorrect adjustment of control parameters, such as incorrectly increasing atmospheric phase supply or reducing liquid phase discharge, thereby causing the entire process system to deviate from the expected operating state, and even in extreme cases, induce equipment malfunction or instability. It exhibits strong concealment and suddenness, and is difficult to identify and correct in a timely manner through conventional monitoring methods.

[0006] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this application is to provide a gas-liquid two-phase flow measurement method and device based on a combination of a differential pressure venturi flow meter and a vortex flow meter, so as to solve the problems in the background art mentioned above.

[0008] To achieve the above objectives, this application provides the following technical solution: a gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flow meter and a vortex flow meter, comprising the following steps:

[0009] The transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter is collected, and the temperature fluctuation amplitude of the corresponding section is collected simultaneously. Based on the preset differential pressure growth rate threshold and temperature offset range, the characteristic data of compressed bubble agglomeration is extracted, and the characteristic data of compressed bubble agglomeration is used as the identification reference input.

[0010] Frequency domain splitting is performed on the characteristic data of compressed bubble agglomeration to extract high-frequency disturbance components in the differential pressure signal. The high-frequency disturbance components are processed according to the preset amplitude attenuation coefficient to construct a suppressed differential pressure signal sequence, which is used as the basis for flow state reconstruction.

[0011] The volumetric flow rate change gradient at the corresponding time is obtained based on the differential pressure signal sequence. The coupling relationship between the differential pressure change rate and the volumetric flow rate offset is established. The density distortion corresponding to abnormal compression is corrected according to the preset coupling deviation range, and the corrected equivalent flow parameters are output.

[0012] Based on the corrected equivalent flow parameters, the range of gas phase compressibility coefficient variation is introduced, the gas compression contribution is calculated separately, the spurious density increment corresponding to the compression effect is removed, and the gas-liquid ratio information corresponding to the true distribution state is output.

[0013] By using gas-liquid ratio information to perform inverse mapping on the pressure difference growth rate threshold, a correspondence between the intensity of compression behavior and the magnitude of flow correction is established. Based on this correspondence, the gas phase flow output value is dynamically compensated to suppress the persistent underestimation deviation caused by bubble agglomeration compression.

[0014] Preferably, the characteristic data of compressed bubble agglomeration are extracted based on a preset pressure difference growth rate threshold and temperature offset range. The specific steps are as follows:

[0015] The transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter is collected, and the temperature fluctuation amplitude of the corresponding section is collected simultaneously. The dynamic pressure response information and temperature response information generated when the gas-liquid two-phase flow passes through the throat region of the differential pressure venturi flow meter are obtained, and the threshold of differential pressure growth rate and temperature deviation range are determined.

[0016] Based on the transient change curve of the differential pressure signal and the temperature fluctuation amplitude of the corresponding section, the differential pressure change rate, differential pressure change amplitude, differential pressure change duration and temperature deviation amplitude are obtained. The differential pressure change rate is correlated with the differential pressure growth rate threshold, and the temperature deviation amplitude is correlated with the temperature deviation amplitude range to extract the characteristic data of compressed bubble agglomeration.

[0017] By using the time relationship between the pressure difference growth rate, the duration of pressure difference change, and the temperature shift amplitude corresponding to the characteristic data of compressed bubble agglomeration, the characteristic data of compressed bubble agglomeration is formed as a reference input for identification, and the characteristic data of compressed bubble agglomeration is extracted based on the pressure difference growth rate threshold and the temperature shift amplitude range.

[0018] Preferably, the suppressed differential pressure signal sequence is constructed, and the specific steps are as follows:

[0019] Based on the information of differential pressure growth rate, differential pressure change amplitude, differential pressure change duration and temperature shift amplitude in the characteristic data of compressed bubble agglomeration, the transient change curve of the differential pressure signal within the corresponding time range is split in the frequency domain to extract the high-frequency disturbance component in the differential pressure signal. The high-frequency disturbance component includes the amplitude of rapid pressure change, the duration of rapid pressure change and the location where rapid pressure change occurs.

[0020] The preset amplitude attenuation coefficient is determined based on the correspondence between the rapid pressure change amplitude, the differential pressure growth rate, and the temperature deviation amplitude in the high-frequency disturbance component. The pressure change amplitude in the high-frequency disturbance component is adjusted according to the preset amplitude attenuation coefficient, while keeping the corresponding time position, change trend, and change duration of the high-frequency disturbance component unchanged.

[0021] The high-frequency disturbance component, after being processed by a preset amplitude attenuation coefficient, is time-correlated with the low-frequency pressure change portion in the transient curve of the differential pressure signal to obtain a suppressed differential pressure signal sequence, which serves as the basis for reconstructing the flow state.

[0022] Preferably, a preset amplitude attenuation coefficient is determined based on the correspondence between the rapid pressure change amplitude, the differential pressure growth rate, and the temperature shift amplitude in the high-frequency disturbance component. This includes determining the corresponding pressure change region based on the characteristic data of compressed bubble agglomeration, so that the extracted high-frequency disturbance component maintains a correspondence with the bubble agglomeration compression behavior, and avoids mistaking the pressure change generated by the normal flow change of the gas-liquid two-phase flow for an abnormal disturbance.

[0023] Preferably, the density distortion corresponding to abnormal compression is corrected according to a preset coupling deviation range, and the corrected equivalent flow parameters are output. The specific steps are as follows:

[0024] Obtain the rate of change of differential pressure and the gradient of change of volumetric flow rate at the corresponding time, establish the coupling relationship between the rate of change of differential pressure and the offset of volumetric flow rate, and determine the preset coupling deviation range based on the corresponding change range between the rate of change of differential pressure and the gradient of change of volumetric flow rate under normal operation of gas-liquid two-phase flow.

[0025] The pressure change portion exceeding the preset coupling deviation range is determined based on the preset coupling deviation range, and the abnormal change portion in the equivalent density parameter of the mixed fluid is adjusted according to the degree of difference between the pressure difference change rate and the corresponding volume flow rate change gradient, thereby correcting the density distortion corresponding to abnormal compression.

[0026] By combining the corrected density parameters, the suppressed differential pressure signal sequence, and the volumetric flow rate change gradient, the corrected equivalent flow parameters are obtained. The corrected equivalent flow parameters include the corrected mixed fluid density information, the corresponding pressure change information, and the overall volumetric flow rate change information.

[0027] Preferably, the coupling relationship between the rate of change of pressure difference and the gradient of change of volumetric flow rate is obtained by: determining a preset coupling deviation range based on the corresponding change range between the rate of change of pressure difference and the gradient of change of volumetric flow rate under normal operation of gas-liquid two-phase flow, and judging the pressure change part corresponding to abnormal compression based on the degree of deviation between the rate of change of pressure difference and the gradient of change of volumetric flow rate.

[0028] Preferably, the gas-liquid ratio information corresponding to the actual distribution state is output. The specific steps are as follows:

[0029] Based on the pressure and temperature change information in the corrected equivalent flow parameters, the range of gas phase compressibility coefficient variation is determined. The corresponding relationship between gas phase volume change and pressure change is obtained based on the corresponding pressure range, temperature range, and gas phase volume change range. The range of influence of pressure change on the gas phase medium causing volume change is determined.

[0030] Based on the gas phase volume change relationship corresponding to the gas phase compressibility coefficient change range, the gas phase volume change under the current pressure state is converted into the corresponding density change. Based on the mixed fluid density information, corresponding pressure change information and overall volume flow rate change information in the corrected equivalent flow parameters, the gas compression contribution is calculated separately, and the density change caused by the actual gas-liquid ratio change is distinguished from the density change caused by the gas phase compression behavior.

[0031] Based on the density change corresponding to the gas compression contribution, the false density increment corresponding to the compression effect is subtracted from the corrected mixed fluid density information to obtain the true density parameter after removing the gas phase compression effect. Then, based on the correspondence between the true density parameter, the gas phase medium density parameter, and the liquid phase medium density parameter, the gas-liquid ratio information corresponding to the true distribution state is output.

[0032] Preferably, the change in gas phase volume corresponding to the change range of gas phase compressibility elastic coefficient under the current pressure state is converted into the corresponding change in density, and the corresponding change in density is used as the contribution of gas phase compression.

[0033] Preferably, the gas phase flow output value is dynamically compensated based on the corresponding relationship to suppress the continuous underestimation deviation caused by bubble agglomeration and compression. The specific steps are as follows:

[0034] The gas-liquid ratio information corresponding to the actual distribution state is obtained as the basis for threshold adjustment. Based on the pressure response range of compressed bubble agglomeration corresponding to different gas-liquid ratio states, the pressure difference growth rate threshold is adjusted in reverse so that the pressure difference growth rate threshold matches the abnormal pressure change characteristics under the current gas-liquid ratio state.

[0035] The deviation between the rate of change of the differential pressure signal and the threshold is obtained based on the adjusted differential pressure growth rate threshold. The intensity of the compression behavior is determined by combining the gas-liquid ratio information. The correspondence between the intensity of the compression behavior and the flow correction amplitude is established based on the degree of change of the differential pressure growth rate exceeding the corresponding threshold, the duration of abnormal pressure change, and the compression influence range corresponding to the current gas-liquid ratio state.

[0036] The gas phase flow correction amplitude is obtained based on the correspondence between compression intensity and flow correction amplitude. The original gas phase flow output value is dynamically compensated according to the current compression intensity. The flow correction amplitude is updated based on the continuously changing gas-liquid ratio information and the pressure difference growth rate, thereby suppressing the continuous underestimation deviation caused by bubble agglomeration compression.

[0037] A gas-liquid two-phase flow measurement device based on a combination of a differential pressure venturi flow meter and a vortex flow meter includes a compression feature extraction module, a disturbance suppression processing module, a density correction calculation module, a gas-liquid ratio analysis module, and a flow dynamic compensation module.

[0038] The compression feature extraction module collects the transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter, and simultaneously collects the temperature fluctuation amplitude of the corresponding section. Based on the preset differential pressure growth rate threshold and temperature offset range, it extracts the characteristic data of compressed bubble agglomeration.

[0039] The disturbance suppression processing module performs frequency domain splitting on the characteristic data of compressed bubble agglomeration, extracts the high-frequency disturbance components in the differential pressure signal, processes the high-frequency disturbance components according to the preset amplitude attenuation coefficient, and constructs the suppressed differential pressure signal sequence.

[0040] The density correction calculation module obtains the volumetric flow rate change gradient at the corresponding time based on the differential pressure signal sequence, establishes the coupling relationship between the differential pressure change rate and the volumetric flow rate offset, corrects the density distortion corresponding to abnormal compression according to the preset coupling deviation range, and outputs the corrected equivalent flow parameters.

[0041] The gas-liquid ratio analysis module introduces the variation range of the gas phase compressibility elastic coefficient based on the corrected equivalent flow parameters, separates and calculates the gas compression contribution, removes the false density increment corresponding to the compression effect, and outputs the gas-liquid ratio information corresponding to the true distribution state.

[0042] The flow dynamic compensation module uses gas-liquid ratio information to perform reverse mapping on the pressure difference growth rate threshold, establishes a correspondence between the intensity of compression behavior and the flow correction magnitude, and dynamically compensates the gas phase flow output value based on the correspondence to suppress the continuous underestimation deviation caused by bubble agglomeration compression.

[0043] The technical effects and advantages provided by this application in the above technical solution are as follows:

[0044] This application extracts the pressure response characteristics corresponding to the bubble agglomeration compression process by acquiring the transient change curve of the differential pressure signal and the temperature fluctuation amplitude in the throat region of a differential pressure venturi flowmeter. Based on the rate of change of differential pressure and the characteristics of temperature change, it identifies local abnormal disturbances, reducing the impact of differential pressure signal offset caused by bubble agglomeration compression. Simultaneously, by combining the correspondence between the differential pressure signal and the volumetric flow rate change, it corrects the density distortion corresponding to abnormal differential pressure changes, avoiding misinterpreting density changes caused by gas-phase compression as an increase in the liquid phase ratio, thus improving the accuracy of obtaining gas-liquid ratio information in gas-liquid two-phase flow.

[0045] This application separates the density effect caused by bubble agglomeration compression by introducing a range of gas-phase compressibility coefficient variations, eliminating spurious density increments corresponding to compression behavior, and establishing a correlation between compression intensity and gas-phase flow correction amplitude based on gas-liquid ratio information, thus achieving dynamic compensation of the gas-phase flow output value. This method reduces the underestimation of gas-phase flow caused by continuous bubble agglomeration compression, making the phase flow results obtained in the combined measurement process of differential pressure Venturi flowmeter and vortex flowmeter more consistent with the actual transport state of gas-liquid two-phase flow, thereby improving the stability and reliability of the measurement process. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0047] Figure 1 This is a flowchart illustrating the overall method of this application.

[0048] Figure 2 A flowchart for constructing the suppressed differential pressure signal sequence for this application.

[0049] Figure 3 This document provides a flowchart of the modified equivalent flow parameters for this application.

[0050] Figure 4 This is a schematic diagram of the system modules of this application. Detailed Implementation

[0051] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art.

[0052] like Figures 1 to 3 As shown, this application provides a method for measuring gas-liquid two-phase flow based on a combination of a differential pressure venturi flow meter and a vortex flow meter, including the following steps:

[0053] Step 1: Acquire the transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter, and simultaneously acquire the temperature fluctuation amplitude of the corresponding section. Extract the characteristic data of compressed bubble agglomeration based on the preset differential pressure growth rate threshold and temperature offset amplitude range. The characteristic data of compressed bubble agglomeration is used as the identification reference input.

[0054] Based on a preset pressure differential growth rate threshold and temperature offset range, the characteristic data of compressed bubble agglomeration are extracted. The specific steps are as follows:

[0055] The transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flowmeter is acquired, and the temperature fluctuation amplitude of the corresponding section is acquired simultaneously to obtain the dynamic pressure response information and temperature response information generated when the gas-liquid two-phase flow passes through the throat region of the venturi flowmeter. In specific implementation, when the gas-liquid two-phase flow enters the differential pressure venturi flowmeter for flow measurement, the differential pressure signal corresponding to the throat region is continuously acquired. The differential pressure signals acquired at different time points are arranged in chronological order to obtain the transient change curve of the differential pressure signal over time.

[0056] The transient curve of the differential pressure signal describes the change in fluid pressure over time as the gas-liquid two-phase flow passes through the contraction and throat regions of the Venturi flowmeter. It includes information on pressure changes caused by overall flow rate variations, as well as transient pressure disturbances caused by local gas-liquid phase distribution changes. Simultaneously, temperature change data is acquired at the temperature acquisition location corresponding to the throat region, and the temperature fluctuation amplitude for the corresponding segment is calculated based on the continuously acquired temperature data, ensuring that each time point in the transient curve of the differential pressure signal corresponds to a specific temperature fluctuation amplitude.

[0057] Temperature fluctuation amplitude is used to describe the temperature changes caused by bubble aggregation, compression, expansion, and changes in the gas-liquid interface state when a gas-liquid two-phase flow passes through the throat region. To ensure a correspondence between the transient change curve of the differential pressure signal and the temperature fluctuation amplitude, the time interval for acquiring the differential pressure signal is kept consistent with the time interval for acquiring the temperature data, so that pressure change information and temperature change information within the same time range can correspond synchronously.

[0058] Furthermore, when acquiring the transient change curve of the differential pressure signal and the amplitude of temperature fluctuation, the pressure change range and temperature change range of the gas-liquid two-phase flow under stable flow conditions are acquired in advance. The maximum rate of change of the differential pressure signal per unit time under stable operating conditions is used as a reference for the differential pressure growth rate threshold, and the temperature change range under stable operating conditions is used as the basis for determining the temperature offset amplitude range, thereby obtaining the differential pressure growth rate threshold and temperature offset amplitude range applicable to the current measurement conditions.

[0059] Based on a preset threshold for differential pressure growth rate and a temperature offset range, features are extracted from the transient change curves of the acquired differential pressure signals and the corresponding temperature fluctuation amplitudes to obtain characteristic data of compressed bubble agglomeration. The acquisition process is as follows:

[0060] Continuous analysis is performed on the pressure change process in the transient curve of the differential pressure signal to obtain the differential pressure change between adjacent time nodes and the rate of differential pressure change per unit time. The rate of differential pressure change is then correlated with a pre-determined threshold for differential pressure growth rate.

[0061] When the rate of change of differential pressure exceeds the threshold of differential pressure growth rate corresponding to normal flow conditions, the area of ​​differential pressure signal change within that time range is designated as an abnormal pressure response area, and the differential pressure change amplitude, differential pressure growth rate, and duration of pressure change corresponding to this area are recorded. Simultaneously, the temperature fluctuation amplitude corresponding to the time of this abnormal pressure response area is extracted, and the temperature fluctuation amplitude is correlated with a pre-determined temperature offset range.

[0062] When the temperature fluctuation amplitude falls within the preset temperature offset range, the temperature change information within that time range is used as the temperature response feature corresponding to the abnormal pressure response region. Using the above method, compressed bubble agglomeration feature data is extracted. This data includes the pressure differential growth rate, pressure differential change amplitude, pressure differential change duration, temperature offset amplitude, temperature change duration, and the time correspondence between pressure differential change and temperature change.

[0063] Since changes in the overall flow rate of a gas-liquid two-phase flow typically cause continuous pressure changes, and when bubble agglomerates undergo compression changes in local flow regions, this leads to a rapid increase in the rate of pressure change, accompanied by a corresponding temperature response change, it is possible to distinguish the local transient changes caused by bubble agglomerate compression behavior from normal flow changes by simultaneously acquiring the differential pressure growth rate and the temperature shift amplitude. The compressed bubble agglomerate characteristic data serves as a reference input for identification, describing the dynamic changes in bubble agglomerate compression behavior as the gas-liquid two-phase flow passes through the throat region of a differential pressure Venturi flowmeter.

[0064] Using compressed bubble agglomeration feature data as an identification reference input, the local abnormal change regions in the transient change curve of the differential pressure signal are described accordingly, so that the pressure change information and temperature change information corresponding to the bubble agglomeration compression behavior are correlated.

[0065] The specific implementation process is as follows:

[0066] The pressure differential growth rate, pressure differential change duration, and temperature shift amplitude in the compressed bubble agglomeration characteristic data are correlated according to their corresponding time relationships, so that each set of compressed bubble agglomeration characteristic data corresponds to a local state change process when the gas-liquid two-phase flow passes through the throat region. When the microbubbles in the gas-liquid two-phase flow aggregate due to changes in flow field velocity and local pressure, the gas-liquid phase ratio in the corresponding bubble agglomeration region changes, causing the transient change curve of the pressure differential signal to show a trend different from the normal flow state. At the same time, the temperature fluctuation amplitude in the corresponding section changes synchronously.

[0067] By compressing the bubble agglomeration characteristic data, the above-mentioned change process can be described, so that the pressure change in the transient change curve of the differential pressure signal is no longer judged based on a single pressure parameter, but is comprehensively characterized based on the pressure change rate, pressure change duration and temperature response change.

[0068] Furthermore, based on the duration of pressure difference changes and temperature changes in the compressed bubble agglomeration characteristic data, a distinction is made between local pressure disturbances occurring within a short period and pressure changes caused by continuous flow rate variations. This ensures that the compressed bubble agglomeration characteristic data accurately reflects the dynamic impact of the bubble agglomeration compression process. The compressed bubble agglomeration characteristic data is retained as an identification reference input for subsequent correction of abnormal density changes caused by bubble agglomeration compression during gas-liquid two-phase flow measurements.

[0069] Finally, the compressed bubble agglomeration characteristic data is used to describe the compressed state of bubble agglomerations during the gas-liquid two-phase flow measurement process, providing corresponding characteristic basis for subsequent flow parameter correction. In specific implementation, based on the pressure difference growth rate and temperature offset information contained in the compressed bubble agglomeration characteristic data, it is determined whether there is a pressure response change corresponding to bubble agglomeration compression when the gas-liquid two-phase flow passes through the throat region of the differential pressure Venturi flowmeter.

[0070] When the pressure growth rate in the transient curve of the differential pressure signal exceeds a preset differential pressure growth rate threshold, and the temperature fluctuation amplitude within the corresponding time range is within a preset temperature offset range, the pressure and temperature change information within that time range are used as the local state description information corresponding to the compressed bubble agglomeration characteristic data. The compressed bubble agglomeration characteristic data is used not only to represent the pressure change amplitude but also to represent the correspondence between the pressure change process and the temperature response process, thereby reflecting the impact of bubble agglomeration compression behavior on the measurement process of the differential pressure venturi flowmeter.

[0071] By acquiring the transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flowmeter, simultaneously acquiring the temperature fluctuation amplitude of the corresponding section, and extracting the characteristic data of compressed bubble agglomeration based on the preset differential pressure growth rate threshold and temperature offset range, and using the characteristic data of compressed bubble agglomeration as an identification reference input, the differential pressure measurement results can be targeted according to the pressure change characteristics and temperature change characteristics corresponding to the compression behavior of bubble agglomeration during subsequent gas-liquid two-phase flow measurement, thereby reducing the impact of local bubble state changes on the gas-liquid two-phase flow measurement results.

[0072] Step 2: Frequency domain splitting is performed on the characteristic data of compressed bubble agglomeration to extract the high-frequency disturbance component in the differential pressure signal. The high-frequency disturbance component is processed according to the preset amplitude attenuation coefficient to construct the suppressed differential pressure signal sequence, which serves as the basis for flow state reconstruction.

[0073] The specific steps for constructing the suppressed differential pressure signal sequence are as follows:

[0074] Frequency domain splitting was performed on the characteristic data of compressed bubble agglomeration to extract high-frequency disturbance components from the differential pressure signal. During the extraction process, the aforementioned characteristic data of compressed bubble agglomeration was used as the input basis for pressure change features. Based on the information contained in the characteristic data of compressed bubble agglomeration, such as the rate of increase of differential pressure, the amplitude of differential pressure change, the duration of differential pressure change, and the temperature offset, the transient change curve of the differential pressure signal within the corresponding time range was split into frequency domain components.

[0075] Frequency domain splitting is used to distinguish the pressure change components corresponding to different periods in the transient curve of the differential pressure signal, thus separating the pressure change component reflecting the overall flow trend of the gas-liquid two-phase flow from the localized rapid pressure change component reflecting the compression behavior of bubble agglomeration. Specifically, when the gas-liquid two-phase flow passes through the throat region of a differential pressure Venturi flowmeter, the overall flow change usually corresponds to a continuous pressure change over a relatively long time range. However, when bubble agglomeration is affected by the local flow state and undergoes compression, recovery, and redistribution, it causes rapid pressure changes over a short time range. This rapid change component corresponds to the high-frequency disturbance component in the differential pressure signal.

[0076] Therefore, the pressure disturbance range is determined based on the duration of differential pressure change corresponding to the characteristic data of compressed bubble agglomerates. Then, based on the pressure change rate, duration, and temperature response within this range, the high-frequency disturbance component in the differential pressure signal is extracted. The high-frequency disturbance component includes the amplitude of the rapid pressure change, the duration of the rapid pressure change, and the location of the rapid pressure change within the corresponding time range. It is used to describe the transient pressure impact of bubble agglomerate compression behavior on the measurement process of the differential pressure venturi flowmeter.

[0077] Furthermore, during the frequency domain splitting process, instead of directly dividing the high-frequency disturbance components using a fixed frequency range, the corresponding pressure change region is determined based on the characteristic data of compressed bubble agglomeration. This ensures that the extracted high-frequency disturbance components correspond to the compression behavior of the bubble agglomeration, thereby avoiding misinterpreting pressure changes caused by normal gas-liquid two-phase flow as abnormal disturbances. Through this method, the high-frequency disturbance components can accurately reflect the local pressure change characteristics caused by compressed bubble agglomeration, providing a basis for subsequent processing of the high-frequency disturbance components based on a preset amplitude attenuation coefficient.

[0078] The high-frequency disturbance component is processed according to a preset amplitude attenuation coefficient. By adjusting the pressure change amplitude corresponding to the high-frequency disturbance component, the influence of abnormal pressure changes caused by bubble agglomeration and compression on the differential pressure signal measurement results is reduced. The adjustment process is as follows:

[0079] A preset amplitude attenuation coefficient is determined based on the correspondence between the differential pressure change amplitude, differential pressure growth rate, and temperature offset amplitude in the compressed bubble agglomeration characteristic data. This preset amplitude attenuation coefficient reflects the degree of pressure disturbance corresponding to the bubble agglomeration compression behavior. When the differential pressure change amplitude, differential pressure growth rate, and temperature offset amplitude corresponding to the compressed bubble agglomeration characteristic data are large, it indicates that the pressure disturbance caused by the bubble agglomeration compression behavior within the corresponding time range is high, and the proportion of abnormal pressure change amplitude in the high-frequency disturbance component is reduced accordingly. When the differential pressure change amplitude, differential pressure growth rate, and temperature offset amplitude variation range corresponding to the compressed bubble agglomeration characteristic data are small, a low degree of amplitude adjustment is maintained to preserve the original pressure change information.

[0080] By using the above method, a preset amplitude attenuation coefficient is set based on the actual pressure change characteristics corresponding to the bubble agglomeration compression behavior, instead of using a uniform processing method for all differential pressure signals, so that the processing of high-frequency disturbance components corresponds to the actual state changes of the gas-liquid two-phase flow.

[0081] In the specific processing, the amplitude of rapid pressure changes in the high-frequency disturbance components is adjusted, while maintaining the corresponding time position, trend, and duration of the changes. This ensures that the processed high-frequency disturbance components can still represent the time range and dynamic process of bubble agglomeration compression. The processed high-frequency disturbance components retain the local disturbance characteristics beyond the overall pressure change of the gas-liquid two-phase flow, while reducing the impact of abnormal pressure amplitudes caused by bubble agglomeration compression. This provides processed pressure disturbance data for the subsequent construction of the suppressed differential pressure signal sequence.

[0082] By processing high-frequency disturbance components with a preset amplitude attenuation coefficient, the differential pressure signal processing can be adjusted to address abnormal changes caused by bubble agglomeration and compression, thereby improving the applicability of pressure parameters in the subsequent flow state reconstruction process.

[0083] A suppressed differential pressure signal sequence is constructed based on the processed high-frequency disturbance components, and this sequence is used as the basis for flow state reconstruction. During the construction process, the high-frequency disturbance components processed by a preset amplitude attenuation coefficient are time-correlated with the corresponding low-frequency pressure change portion in the transient curve of the differential pressure signal, so that the processed differential pressure signal sequence maintains the temporal continuity of the original pressure change process.

[0084] The low-frequency pressure change component is used to represent the pressure response corresponding to the overall flow state change of the gas-liquid two-phase flow. The processed high-frequency disturbance component is used to represent the local pressure change characteristics after reducing the impact of bubble agglomeration and compression. The suppressed pressure difference signal sequence is obtained by processing the two components.

[0085] Specifically, the suppressed differential pressure signal sequence retains the effective information generated by the overall flow rate change, flow state change and pressure change in the throat region of the differential pressure venturi flowmeter for gas-liquid two-phase flow, while reducing the impact of local abnormal pressure fluctuations caused by compressed bubble agglomeration, so that the differential pressure signal sequence can more closely approximate the pressure change process corresponding to the actual flow state of gas-liquid two-phase flow.

[0086] Furthermore, the differential pressure signal sequence serves as the basis for flow state reconstruction, used to subsequently obtain the corresponding equivalent flow parameters. Since this differential pressure signal sequence has been specifically adjusted for high-frequency disturbance components based on the characteristic data of compressed bubble agglomeration, it can reduce pressure distortion caused by local bubble state changes, enabling the subsequent flow state description process to be based on more stable pressure change information.

[0087] Frequency domain splitting is performed on the characteristic data of compressed bubble agglomeration. High-frequency disturbance components in the differential pressure signal are extracted and processed according to the preset amplitude attenuation coefficient. The suppressed differential pressure signal sequence is then constructed so that the differential pressure signal sequence can be used as the basis for flow state reconstruction. This reduces the impact of abnormal pressure changes caused by bubble agglomeration compression on the gas-liquid two-phase flow measurement process and improves the accuracy of flow parameter acquisition in the combined measurement process of differential pressure venturi flowmeter and vortex flowmeter.

[0088] Step 3: Based on the differential pressure signal sequence, obtain the volumetric flow rate change gradient at the corresponding time, establish the coupling relationship between the differential pressure change rate and the volumetric flow rate offset, correct the density distortion corresponding to abnormal compression according to the preset coupling deviation range, and output the corrected equivalent flow parameters.

[0089] Based on the preset coupling deviation range, the density distortion corresponding to abnormal compression is corrected, and the corrected equivalent flow parameters are output. The specific steps are as follows:

[0090] The volumetric flow rate change gradient at corresponding moments is obtained based on the suppressed differential pressure signal sequence, ensuring a time-dependent relationship between the pressure change information acquired by the differential pressure venturi flowmeter and the volumetric flow rate change information acquired by the vortex flowmeter. The acquisition process is as follows:

[0091] The obtained suppressed differential pressure signal sequence is used as the pressure change reference data, and the overall volumetric flow rate data of the gas-liquid two-phase flow output by the vortex flowmeter is acquired simultaneously. The volumetric flow rate data is collected at continuous time points to ensure that the volumetric flow rate value at different time points corresponds to the pressure change value in the suppressed differential pressure signal sequence.

[0092] Based on the volumetric flow rate changes between consecutive time points, the volumetric flow rate change gradient at corresponding moments is obtained. This gradient describes the degree, direction, and duration of change in the overall volumetric flow rate of the gas-liquid two-phase flow within a unit time range. Specifically, the volumetric flow rate changes between adjacent time points are correlated to obtain the dynamic characteristics corresponding to the overall transport state changes of the gas-liquid two-phase flow. When the overall flow rate of the gas-liquid two-phase flow changes, the suppressed differential pressure signal sequence maintains a corresponding trend with the volumetric flow rate change gradient; that is, pressure changes and volumetric flow rate changes have a corresponding relationship. When bubble aggregation and compression cause local pressure changes, the degree of pressure change in the suppressed differential pressure signal sequence deviates from the normal range corresponding to the volumetric flow rate change gradient.

[0093] Therefore, by obtaining the volumetric flow rate change gradient at the corresponding time point based on the suppressed differential pressure signal sequence, a time synchronization relationship is established between the pressure change information of the differential pressure venturi flowmeter and the overall flow rate change information of the vortex flowmeter. The volumetric flow rate change gradient includes the volumetric flow rate change amplitude, direction, and duration at the corresponding time point, which are used to subsequently establish the coupling relationship between the differential pressure change rate and the volumetric flow rate offset.

[0094] By using the above method, we can avoid judging the state of gas-liquid two-phase flow solely based on changes in pressure difference signals. Instead, we can simultaneously refer to changes in overall volumetric flow rate, providing a basis for identifying abnormal pressure responses caused by bubble agglomeration and compression.

[0095] Based on the suppressed differential pressure signal sequence and the corresponding volumetric flow rate change gradient, a coupling relationship between the differential pressure change rate and the volumetric flow rate offset is established to determine whether the pressure change corresponds to the overall flow rate change. During the establishment process, the differential pressure change between different time points is obtained from the suppressed differential pressure signal sequence, and the differential pressure change rate is obtained based on the differential pressure change over a continuous time range. The differential pressure change rate is used to represent the dynamic degree of pressure change in the throat region of the differential pressure venturi flowmeter.

[0096] Furthermore, the rate of pressure difference change is correlated with the gradient of volumetric flow rate change within the corresponding time range to obtain the relationship between their changing trends, magnitudes, and time responses, thereby establishing a coupling relationship between the rate of pressure difference change and the volumetric flow rate deviation. This coupling relationship is used to describe the correspondence between pressure changes and volumetric flow rate changes under normal gas-liquid two-phase flow conditions, as well as the deviation between pressure changes and volumetric flow rate changes under bubble agglomeration and compression conditions.

[0097] Specifically, when the overall flow rate of the gas-liquid two-phase flow changes, the rate of change of pressure difference and the gradient of change of volumetric flow rate will maintain a corresponding trend, and the change of pressure difference can reflect the overall flow rate change. When bubbles agglomerate into the throat region of the venturi tube and cause local compression changes, although the pressure difference signal will change, the overall volumetric flow rate change obtained by the vortex flow meter will not change accordingly. At this time, a shift occurs between the rate of change of pressure difference and the gradient of change of volumetric flow rate.

[0098] To describe the degree of this deviation, a preset coupling deviation range is determined based on the corresponding range of changes in the rate of change of pressure difference and the gradient of change of volumetric flow rate under normal operating conditions of the gas-liquid two-phase flow. The preset coupling deviation range represents the allowable deviation between pressure and flow rate changes under normal flow conditions. When the deviation between the rate of change of pressure difference and the gradient of change of volumetric flow rate is within this range, it indicates that the current pressure change mainly originates from the overall flow rate change; when the deviation exceeds this range, it indicates that the current pressure change is affected by the compression behavior of localized bubble agglomeration.

[0099] By establishing a coupling relationship between the rate of pressure difference change and the volumetric flow rate deviation, the pressure changes generated during the gas-liquid two-phase flow measurement process can be distinguished based on the overall volumetric flow rate change, avoiding the direct use of pressure fluctuations caused by local bubble state changes as the basis for flow rate changes.

[0100] The density distortion corresponding to abnormal compression is corrected based on a preset coupling deviation range, so that the spurious density change caused by abnormal bubble agglomeration compression is adjusted in the equivalent flow parameter calculation process. In specific implementation, based on the coupling relationship between the rate of pressure change and the gradient of volumetric flow rate change, the portion of pressure change exceeding the preset coupling deviation range is determined, and this portion of pressure change is taken as the influencing factor corresponding to abnormal compression.

[0101] Because the compression behavior of bubble agglomeration can cause changes in the local gas-liquid distribution in the throat region of the Venturi tube, the pressure changes collected by the differential pressure Venturi flowmeter cannot fully represent the overall gas-liquid two-phase flow state. Therefore, it is necessary to correct the density distortion caused by abnormal compression based on the degree of deviation between the pressure difference change and the volumetric flow rate change.

[0102] During the correction process, the pressure influence range corresponding to abnormal compression is determined based on the degree of difference between the rate of pressure change exceeding the preset coupling deviation range and the corresponding volumetric flow rate change gradient. The abnormal change portion of the equivalent density parameter of the mixed fluid is then adjusted according to this pressure influence range. The density distortion correction process adjusts the spurious density increment corresponding to abnormal compression without altering the true density change information corresponding to the overall flow change in the gas-liquid two-phase flow.

[0103] Specifically, when the rate of change of pressure difference increases but the gradient of change of volumetric flow rate does not change accordingly, it indicates that the pressure change is not entirely due to the change in flow rate, but is affected by the compression of bubble agglomeration. In this case, the density change corresponding to the abnormal pressure contribution is separated from the original equivalent density parameter, so that the corrected density parameter is closer to the actual distribution state of gas-liquid two-phase flow.

[0104] By using the above method, the suppressed differential pressure signal sequence, the volumetric flow rate change gradient, and the coupling relationship between the differential pressure change rate and the volumetric flow rate offset are used together to correct density distortion, so that the local pressure anomaly caused by the compression of bubble agglomerates in the differential pressure venturi flow meter can be specifically addressed.

[0105] Finally, based on the measured parameters corrected for density distortion, the corrected equivalent flow parameters are output, serving as the basis for calculating the gas-liquid two-phase flow ratio and for dynamic flow compensation. In practice, the density parameters corrected within a preset coupling deviation range are correlated with the suppressed differential pressure signal sequence, and combined with the overall flow change information corresponding to the volumetric flow rate change gradient to obtain the corrected equivalent flow parameters.

[0106] The corrected equivalent flow parameters include the corrected mixed fluid density information, corresponding pressure change information, and overall volumetric flow rate change information, used to describe the actual flow state of the gas-liquid two-phase flow after removing the influence of abnormal bubble agglomeration compression. Because these equivalent flow parameters simultaneously consider the pressure change corresponding to the differential pressure Venturi flowmeter and the overall volumetric flow rate change corresponding to the vortex flowmeter, they can avoid the deviation in gas-liquid ratio calculation caused by the influence of local bubble state changes on a single pressure parameter.

[0107] Furthermore, the corrected equivalent flow parameters maintain the time correspondence with the differential pressure signal sequence and the volumetric flow rate change gradient, enabling the gas-liquid two-phase flow state changes over a continuous time range to be described by continuous parameters.

[0108] By acquiring the volumetric flow rate change gradient at the corresponding moment through the differential pressure signal sequence, a coupling relationship between the differential pressure change rate and the volumetric flow rate deviation is established. Based on the preset coupling deviation range, the density distortion corresponding to abnormal compression is corrected, and the corrected equivalent flow parameters are output. This effectively weakens the local density anomaly caused by bubble agglomeration compression during the combined measurement process of differential pressure venturi flow meter and vortex flow meter, and improves the accuracy of the gas phase flow rate and liquid phase flow rate calculation results in gas-liquid two-phase flow.

[0109] Step 4: Based on the corrected equivalent flow parameters, introduce the variation range of the gas phase compressibility elastic coefficient, separate and calculate the gas compression contribution, remove the spurious density increment corresponding to the compression effect, and output the gas-liquid ratio information corresponding to the true distribution state.

[0110] The specific steps to output the gas-liquid ratio information corresponding to the actual distribution state are as follows:

[0111] Based on the corrected equivalent flow parameters, a range of variation in the gas-phase compressibility elastic coefficient is introduced to determine the corresponding range of volume changes in the gas phase medium caused by pressure variations in a gas-liquid two-phase flow, and to obtain the degree of influence of gas-phase compression behavior on the density changes of the mixed fluid. The specific implementation process is as follows:

[0112] The aforementioned corrected equivalent flow parameters are used as the basis for the analysis of the gas-liquid two-phase flow state. These parameters include the corrected mixed fluid density information, corresponding pressure change information, and overall volumetric flow rate change information. Since the gas phase in a gas-liquid two-phase flow is compressible, while the liquid phase exhibits less volume change under the same pressure change conditions, pressure changes within the measurement area of ​​the differential pressure Venturi flowmeter will not only cause changes in the gas-liquid ratio but also in the gas phase volume, thus leading to changes in the mixed fluid density. To distinguish between the density change caused by gas phase compression and the density change caused by the actual gas-liquid ratio change, the range of variation for the gas phase compressibility elastic coefficient is determined based on the pressure and temperature change information in the corrected equivalent flow parameters.

[0113] In practice, based on the corresponding pressure range, temperature range, and gas phase volume change range during the gas-liquid two-phase flow measurement process, the correspondence between gas phase volume change and pressure change under different pressure states is determined, and this correspondence is used as the range of variation of the gas phase compressibility coefficient. The range of variation of the gas phase compressibility coefficient is used to describe the range of volume change of the gas phase medium when affected by pressure changes, including the degree of gas phase volume change, the degree of gas phase compressibility response, and the degree of influence of corresponding density under different pressure conditions.

[0114] By introducing the variation range of the gas-phase compressibility coefficient, the gas-phase compression behavior can be described as an independent influencing factor, rather than directly attributing the increase in the density of the mixed fluid entirely to the increase in the liquid phase proportion. Furthermore, based on the pressure change state corresponding to the corrected equivalent flow parameters, the pressure range of the current gas-liquid two-phase flow is correlated with the variation range of the gas-phase compressibility coefficient to obtain the influence range of the volume change corresponding to gas-phase compression under the current pressure state.

[0115] The range of gas phase compressibility coefficient variation serves as the basis for subsequent separation calculations of gas compression contribution. It is used to determine the range of density influence of gas phase medium due to pressure changes, thereby reducing the impact of bubble agglomeration compression leading to excessively high mixed fluid density.

[0116] The gas compression contribution is calculated separately based on the corrected equivalent flow parameters and the variation range of the gas-phase compressibility coefficient, thus distinguishing the density change caused by gas-phase pressure changes from the overall density change process. In practice, the density change of the mixed fluid under the current gas-liquid two-phase flow state is obtained based on the corrected mixed fluid density information, corresponding pressure change information, and overall volumetric flow rate change information in the corrected equivalent flow parameters. Because the gas phase volume changes with pressure during bubble agglomeration and compression, the volume occupied by the gas phase in the measurement area changes, causing a change in the mass distribution per unit volume of the mixed fluid, thus manifesting as a change in mixed density. However, this density change does not entirely represent an increase in liquid phase content but includes the density change contribution caused by gas-phase compression.

[0117] Therefore, the gas compression contribution is calculated separately based on the gas phase volume change relationship corresponding to the range of gas phase compressibility coefficient variation. The gas compression contribution represents the portion of the gas phase medium that affects the density parameters of the mixed fluid after a pressure change, including the density change corresponding to the gas phase volume change and the degree of influence of this density change on the overall mixed density change. In specific implementation, the gas phase volume change corresponding to the range of gas phase compressibility coefficient variation under the current pressure state is converted into the corresponding density change, and this density change is used as the gas phase compression contribution.

[0118] Furthermore, the gas-phase compression contribution is correlated with the corrected mixed fluid density information to distinguish between density changes caused by actual gas-liquid ratio changes and density changes caused by gas-phase compression behavior. When the degree of bubble agglomeration compression increases, the range of gas phase volume change corresponding to the change range of gas phase compressibility coefficient increases, and the corresponding gas compression contribution increases; when the degree of bubble agglomeration compression decreases, the range of gas phase volume change decreases, and the corresponding gas compression contribution decreases.

[0119] By employing the above method, the density effect caused by gas-phase compression can be dynamically described based on pressure changes, avoiding the direct conversion of density increases caused by gas-phase compression into increases in liquid phase proportion. The gas compression contribution serves as the source of density changes corresponding to the compression effect, and is used to subsequently remove spurious density increments associated with the compression effect, making the obtained gas-liquid ratio information closer to the true distribution.

[0120] Based on the gas compression contribution obtained through separation calculations, the spurious density increment corresponding to the compression effect is removed, and the gas-liquid ratio information corresponding to the true distribution state is output. The specific process is as follows:

[0121] Based on the mixed fluid density information in the corrected equivalent flow parameters, the density change corresponding to the gas compression contribution is subtracted to obtain the true density parameters after removing the influence of gas-phase compression. False density increments refer to the increase in mixed fluid density within the measurement area caused by the reduction in gas phase volume during bubble agglomeration compression, but without a corresponding change in the actual gas-liquid ratio. Since this false density increment originates from gas-phase compression behavior rather than an increase in liquid phase content, directly calculating the gas-liquid ratio based on unprocessed mixed density information will lead to an overestimation of the liquid phase ratio, further resulting in an underestimation of the gas phase flow output value.

[0122] The gas compression contribution obtained from the separation calculation is used as the basis for removing spurious density increments. The corresponding compression effect is removed from the corrected mixed fluid density information, so that the remaining density change can reflect the true ratio change of the gas and liquid phases. Furthermore, based on the true density parameters after removing spurious density increments, and the correspondence between the gas phase medium density parameters and the liquid phase medium density parameters, the gas-liquid ratio information corresponding to the true distribution state is obtained.

[0123] Gas-liquid ratio information includes both gas phase ratio and liquid phase ratio information, used to describe the actual distribution of different phase media in a gas-liquid two-phase flow. Specifically, after removing the spurious density increment caused by gas phase compression, the remaining density change can more accurately reflect the changes in gas phase content and liquid phase content, making the gas-liquid ratio information unaffected by the compression behavior of local bubble agglomeration.

[0124] By introducing the variation range of the gas phase compressibility elastic coefficient through the corrected equivalent flow parameters, separating and calculating the gas compression contribution, stripping away the false density increment corresponding to the compression effect, and outputting the gas-liquid ratio information corresponding to the true distribution state, the local density anomaly caused by bubble agglomeration compression during the gas-liquid two-phase flow measurement process can be specifically handled, improving the accuracy of gas-liquid ratio information acquisition and reducing the continuous underestimation bias caused by density misjudgment during the gas phase flow calculation process.

[0125] Step 5: Use the gas-liquid ratio information to perform reverse mapping on the pressure difference growth rate threshold, establish the correspondence between the compression behavior intensity and the flow correction amplitude, and dynamically compensate the gas phase flow output value based on the correspondence to suppress the continuous underestimation deviation caused by bubble agglomeration compression.

[0126] The gas phase flow output value is dynamically compensated based on the corresponding relationship to suppress the persistent underestimation deviation caused by bubble agglomeration and compression. The specific steps are as follows:

[0127] By using gas-liquid ratio information to perform a reverse mapping on the pressure differential growth rate threshold, the threshold can be dynamically adjusted according to the actual distribution state of the gas-liquid two-phase flow to adapt to the pressure change characteristics corresponding to the bubble agglomeration and compression behavior under different gas-liquid ratio conditions. Specifically, the gas-liquid ratio information corresponding to the aforementioned actual distribution state is used as the basis for threshold adjustment. This gas-liquid ratio information includes both gas phase and liquid phase ratio information, used to describe the phase distribution of the gas-liquid two-phase medium under the current measurement state.

[0128] Since the compression behavior of bubble agglomeration is mainly affected by changes in the gas phase content, changes in the gas phase ratio will alter the number of bubbles, the degree of bubble aggregation, and the range of volume changes caused by pressure variations. This, in turn, will change the range of differential pressure change rates in the throat region of the differential pressure venturi flowmeter. Therefore, based on the pressure response range of compressed bubble agglomeration under different gas-liquid ratios, the original differential pressure growth rate threshold is adjusted inversely to match the abnormal pressure change characteristics under the current gas-liquid ratio state.

[0129] Specifically, when the gas phase ratio increases, the proportion of compressible gas phase in the gas-liquid two-phase flow increases, and the pressure disturbance range caused by bubble agglomeration compression expands. At this point, the judgment range corresponding to the pressure difference growth rate threshold is reduced based on the gas-liquid ratio information, allowing smaller abnormal pressure changes to be identified as impacts of compression behavior. Conversely, when the liquid phase ratio increases and the gas phase ratio decreases, the pressure response caused by gas phase compression weakens, correspondingly expanding the pressure difference growth rate threshold range, making the pressure change judgment more consistent with the current flow state. This inverse mapping relationship is established based on the correspondence between the range of pressure difference growth rate changes and the degree of impact of bubble agglomeration compression under different gas-liquid ratio conditions. This ensures that the pressure difference growth rate threshold is no longer a fixed parameter but is dynamically adjusted according to changes in the gas-liquid ratio information.

[0130] By using gas-liquid ratio information to perform reverse mapping on the pressure difference growth rate threshold, the gas-liquid ratio information corresponding to the actual distribution state can participate in the compression behavior identification process, improve the matching degree between the judgment of bubble agglomeration compression state and the current gas-liquid two-phase flow state, and provide a dynamic threshold basis for subsequently establishing the correspondence between compression behavior intensity and flow correction amplitude.

[0131] A correlation between compression intensity and flow correction magnitude is established based on the differential pressure growth rate threshold adjusted by inverse mapping, ensuring that the degree of bubble agglomeration compression corresponds to the degree of gas phase flow compensation. When establishing this correlation, the deviation between the current differential pressure signal change rate and the adjusted differential pressure growth rate threshold is obtained, and the corresponding compression intensity is determined by combining this with gas-liquid ratio information. Compression intensity describes the degree to which bubble agglomeration compression affects the gas-liquid two-phase flow measurement results, including the extent to which the differential pressure growth rate exceeds the corresponding threshold, the duration of abnormal pressure changes, and the range of compression influence corresponding to the current gas-liquid ratio state.

[0132] When the differential pressure growth rate exceeds the adjusted threshold range, it indicates that the current pressure change includes the effect of bubble agglomeration compression. The intensity of the compression behavior is determined based on the degree of deviation of the differential pressure growth rate, its duration, and the gas-liquid ratio. When the differential pressure growth rate deviates only slightly from the corresponding threshold, it indicates a low degree of bubble agglomeration compression and a small impact on the gas phase flow output, corresponding to a smaller flow correction range. When the differential pressure growth rate exceeds the corresponding threshold significantly and its duration increases, it indicates a higher degree of bubble agglomeration compression, corresponding to a larger flow correction range.

[0133] A correlation between compression intensity and flow correction magnitude is established based on the degree of underestimation of gas phase flow rate corresponding to different compression intensity, allowing the flow correction magnitude to vary with the degree of influence of bubble agglomeration compression. This correlation not only considers changes in the pressure difference growth rate but also incorporates gas-liquid ratio information to adjust the range of gas phase compression influence, enabling different flow correction results to be obtained under different gas-liquid ratio conditions for the same degree of pressure difference change.

[0134] By establishing a correspondence between the intensity of compression behavior and the magnitude of flow correction, the gas phase flow compensation process is transformed from a fixed-amplitude adjustment to a dynamic adjustment method based on the dynamic changes in the compression state of bubble agglomeration. This avoids overcompensation when the compression behavior is weak, and also avoids insufficient compensation when the compression behavior is continuous.

[0135] The gas phase flow rate output value is dynamically compensated based on the correlation between compression intensity and flow rate correction magnitude to suppress persistent underestimation caused by bubble agglomeration compression. The dynamic compensation is as follows:

[0136] The gas-liquid ratio information corresponding to the actual distribution state, the adjusted differential pressure growth rate threshold, and the correspondence between compression intensity and flow correction amplitude are used as the basis for gas phase flow compensation. The original gas phase flow output value is determined based on the gas-liquid ratio information corresponding to the actual distribution state and the overall volumetric flow rate information. When bubble agglomeration compression behavior is detected, causing an underestimation of the gas phase flow, the corresponding flow correction amplitude is obtained based on the current compression intensity, and the original gas phase flow output value is dynamically compensated. Since bubble agglomeration compression leads to an increase in local mixing density, the gas-liquid ratio information obtained based on differential pressure measurement may show an underestimation of the gas phase ratio. Therefore, it is necessary to restore the underestimated gas phase flow based on the compensation amplitude corresponding to the compression intensity.

[0137] Specifically, when the intensity of compression increases, it indicates an increase in the spurious density increment caused by bubble agglomeration compression, leading to a greater underestimation of gas phase flow. In this case, the flow correction amplitude is increased according to the corresponding relationship to improve the gas phase flow output value. Conversely, when the intensity of compression decreases, it indicates a weakening effect of bubble agglomeration compression. In this case, the flow correction amplitude is reduced to maintain the gas phase flow output value in line with the current gas-liquid ratio. The dynamic compensation process updates the flow correction amplitude based on continuously changing gas-liquid ratio information and the rate of pressure difference growth, ensuring that the ongoing bubble agglomeration compression behavior receives continuous compensation and preventing the gas phase flow output value from remaining persistently low during long-term operation.

[0138] By inversely mapping the pressure difference growth rate threshold using gas-liquid ratio information, a correspondence between the intensity of compression behavior and the magnitude of flow correction is established. Based on this correspondence, the gas phase flow output value is dynamically compensated, thereby suppressing the persistent underestimation deviation caused by bubble agglomeration compression and improving the accuracy and stability of the gas phase flow output results in the gas-liquid two-phase flow process measured by the combination of differential pressure Venturi flowmeter and vortex flowmeter.

[0139] Through the above dynamic compensation method, the gas-liquid two-phase flow measurement process can simultaneously consider the changes in gas-liquid ratio, the degree of influence of compressed bubble agglomeration, and the characteristics of differential pressure changes, thereby achieving targeted correction of measurement deviations caused by bubble agglomeration compression.

[0140] like Figure 4 As shown, this application provides a gas-liquid two-phase flow measurement device based on a combination of a differential pressure venturi flow meter and a vortex flow meter, including a compression feature extraction module, a disturbance suppression processing module, a density correction calculation module, a gas-liquid ratio analysis module, and a flow dynamic compensation module.

[0141] The compression feature extraction module collects the transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter, and simultaneously collects the temperature fluctuation amplitude of the corresponding section. Based on the preset differential pressure growth rate threshold and temperature offset range, it extracts the characteristic data of compressed bubble agglomeration.

[0142] The disturbance suppression processing module performs frequency domain splitting on the characteristic data of compressed bubble agglomeration, extracts the high-frequency disturbance components in the differential pressure signal, processes the high-frequency disturbance components according to the preset amplitude attenuation coefficient, and constructs the suppressed differential pressure signal sequence.

[0143] The density correction calculation module obtains the volumetric flow rate change gradient at the corresponding time based on the differential pressure signal sequence, establishes the coupling relationship between the differential pressure change rate and the volumetric flow rate offset, corrects the density distortion corresponding to abnormal compression according to the preset coupling deviation range, and outputs the corrected equivalent flow parameters.

[0144] The gas-liquid ratio analysis module introduces the variation range of the gas phase compressibility elastic coefficient based on the corrected equivalent flow parameters, separates and calculates the gas compression contribution, removes the false density increment corresponding to the compression effect, and outputs the gas-liquid ratio information corresponding to the true distribution state.

[0145] The flow dynamic compensation module uses gas-liquid ratio information to perform reverse mapping on the pressure difference growth rate threshold, establishes a correspondence between the intensity of compression behavior and the flow correction magnitude, and dynamically compensates the gas phase flow output value based on the correspondence to suppress the continuous underestimation deviation caused by bubble agglomeration compression.

[0146] This invention provides a gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flow meter and a vortex flow meter. This method is implemented using the aforementioned gas-liquid two-phase flow measurement device based on a combination of a differential pressure venturi flow meter and a vortex flow meter. For details of the specific method and process of the gas-liquid two-phase flow measurement device based on a combination of a differential pressure venturi flow meter and a vortex flow meter, please refer to the aforementioned embodiment of the gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flow meter and a vortex flow meter, which will not be repeated here.

[0147] The foregoing has only described certain exemplary embodiments of this application by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of this application. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of this application.

Claims

1. A method for measuring gas-liquid two-phase flow based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter, characterized in that, Includes the following steps: The transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter is collected, and the temperature fluctuation amplitude of the corresponding section is collected simultaneously. Based on the preset differential pressure growth rate threshold and the temperature offset range, the characteristic data of compressed bubble agglomeration are extracted. Frequency domain splitting is performed on the characteristic data of compressed bubble agglomeration to extract high-frequency disturbance components in the differential pressure signal. The high-frequency disturbance components are processed according to a preset amplitude attenuation coefficient to construct a suppressed differential pressure signal sequence. The volumetric flow rate change gradient at the corresponding time is obtained based on the differential pressure signal sequence. The coupling relationship between the differential pressure change rate and the volumetric flow rate offset is established. The density distortion corresponding to abnormal compression is corrected according to the preset coupling deviation range, and the corrected equivalent flow parameters are output. Based on the corrected equivalent flow parameters, the range of gas phase compressibility coefficient variation is introduced, the gas compression contribution is calculated separately, the spurious density increment corresponding to the compression effect is removed, and the gas-liquid ratio information corresponding to the true distribution state is output. By using gas-liquid ratio information to perform inverse mapping on the pressure difference growth rate threshold, a correspondence between compression behavior intensity and flow correction magnitude is established. Based on this correspondence, the gas phase flow output value is dynamically compensated to suppress the persistent underestimation deviation caused by bubble agglomeration compression.

2. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 1, characterized in that, Based on a preset pressure differential growth rate threshold and temperature offset range, the characteristic data of compressed bubble agglomeration are extracted. The specific steps are as follows: The transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter is collected, and the temperature fluctuation amplitude of the corresponding section is collected simultaneously. The dynamic pressure response information and temperature response information generated when the gas-liquid two-phase flow passes through the throat region of the differential pressure venturi flow meter are obtained, and the threshold of differential pressure growth rate and temperature deviation range are determined. Based on the transient change curve of the differential pressure signal and the temperature fluctuation amplitude of the corresponding section, the differential pressure change rate, differential pressure change amplitude, differential pressure change duration, and temperature offset amplitude are obtained. The differential pressure change rate is correlated with the differential pressure growth rate threshold, and the temperature offset amplitude is correlated with the temperature offset amplitude range to extract the characteristic data of compressed bubble agglomeration.

3. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 2, characterized in that, The specific steps for constructing the suppressed differential pressure signal sequence are as follows: Based on the information of differential pressure growth rate, differential pressure change amplitude, differential pressure change duration and temperature offset amplitude in the characteristic data of compressed bubble agglomeration, frequency domain splitting is performed on the transient change curve of differential pressure signal within the corresponding time range to extract high-frequency disturbance components in differential pressure signal. The preset amplitude attenuation coefficient is determined based on the correspondence between the rapid pressure change amplitude, the differential pressure growth rate, and the temperature deviation amplitude in the high-frequency disturbance component, and the pressure change amplitude in the high-frequency disturbance component is adjusted according to the preset amplitude attenuation coefficient. The high-frequency disturbance component, after being processed by a preset amplitude attenuation coefficient, is time-correlated with the low-frequency pressure change portion in the transient curve of the differential pressure signal to obtain the suppressed differential pressure signal sequence.

4. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 3, characterized in that, The high-frequency disturbance components include the amplitude of the rapid pressure change, the duration of the rapid pressure change, and the location where the rapid pressure change occurs.

5. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 4, characterized in that, Based on a preset coupling deviation range, the density distortion corresponding to abnormal compression is corrected, and the corrected equivalent flow parameters are output. The specific steps are as follows: Obtain the rate of change of differential pressure and the gradient of change of volumetric flow rate at the corresponding time, establish the coupling relationship between the rate of change of differential pressure and the offset of volumetric flow rate, and determine the preset coupling deviation range based on the corresponding change range between the rate of change of differential pressure and the gradient of change of volumetric flow rate under normal operation of gas-liquid two-phase flow. The pressure change portion exceeding the preset coupling deviation range is determined based on the preset coupling deviation range, and the abnormal change portion in the equivalent density parameter of the mixed fluid is adjusted according to the degree of difference between the pressure difference change rate and the corresponding volume flow rate change gradient, thereby correcting the density distortion corresponding to abnormal compression. By combining the corrected density parameters, the suppressed differential pressure signal sequence, and the volumetric flow rate change gradient, the corrected equivalent flow parameters are obtained. The corrected equivalent flow parameters include the corrected mixed fluid density information, the corresponding pressure change information, and the overall volumetric flow rate change information.

6. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 5, characterized in that, The coupling relationship between the rate of change of pressure difference and the gradient of change of volumetric flow rate is obtained. Specifically, the preset coupling deviation range is determined based on the corresponding change range between the rate of change of pressure difference and the gradient of change of volumetric flow rate under normal operation of gas-liquid two-phase flow, and the pressure change part corresponding to abnormal compression is determined based on the degree of deviation between the rate of change of pressure difference and the gradient of change of volumetric flow rate.

7. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 5, characterized in that, The specific steps to output the gas-liquid ratio information corresponding to the actual distribution state are as follows: The range of gas phase compressibility coefficient variation is determined based on the pressure and temperature change information in the corrected equivalent flow parameters. Based on the gas phase volume change relationship corresponding to the gas phase compressibility coefficient change range, the gas phase volume change under the current pressure state is converted into the corresponding density change. Based on the mixed fluid density information, corresponding pressure change information and overall volume flow rate change information in the corrected equivalent flow parameters, the gas compression contribution is calculated separately, and the density change caused by the actual gas-liquid ratio change is distinguished from the density change caused by the gas phase compression behavior. Based on the density change corresponding to the gas compression contribution, the false density increment corresponding to the compression effect is subtracted from the corrected mixed fluid density information to obtain the true density parameter after removing the gas phase compression effect. Then, based on the correspondence between the true density parameter, the gas phase medium density parameter, and the liquid phase medium density parameter, the gas-liquid ratio information corresponding to the true distribution state is output.

8. The gas-liquid two-phase flow measurement method based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 7, characterized in that, The change in gas phase volume corresponding to the range of gas phase compressibility elastic coefficient under the current pressure is converted into the corresponding change in density, and the corresponding change in density is used as the contribution of gas phase compression.

9. A method for measuring gas-liquid two-phase flow based on a combination of a differential pressure venturi flowmeter and a vortex flowmeter according to claim 7, characterized in that, The gas phase flow output value is dynamically compensated based on the corresponding relationship to suppress the persistent underestimation deviation caused by bubble agglomeration and compression. The specific steps are as follows: The gas-liquid ratio information corresponding to the actual distribution state is obtained as the basis for threshold adjustment. Based on the pressure response range of compressed bubble agglomeration corresponding to different gas-liquid ratio states, the pressure difference growth rate threshold is adjusted in reverse. The deviation between the rate of change of the differential pressure signal and the threshold is obtained based on the adjusted differential pressure growth rate threshold. The intensity of the compression behavior is determined by combining the gas-liquid ratio information. The correspondence between the intensity of the compression behavior and the flow correction amplitude is established based on the degree of change of the differential pressure growth rate exceeding the corresponding threshold, the duration of abnormal pressure change, and the compression influence range corresponding to the current gas-liquid ratio state. The gas phase flow correction amplitude is obtained based on the correspondence between compression intensity and flow correction amplitude. The original gas phase flow output value is dynamically compensated according to the current compression intensity. The flow correction amplitude is updated based on the continuously changing gas-liquid ratio information and the pressure difference growth rate, thereby suppressing the continuous underestimation deviation caused by bubble agglomeration compression.

10. A gas-liquid two-phase flow measurement device based on a combination of a differential pressure Venturi flowmeter and a vortex flowmeter, used to implement the gas-liquid two-phase flow measurement method based on the combination of a differential pressure Venturi flowmeter and a vortex flowmeter as described in any one of claims 1-9, characterized in that, It includes a compression feature extraction module, a disturbance suppression processing module, a density correction calculation module, a gas-liquid ratio analysis module, and a flow dynamic compensation module; The compression feature extraction module collects the transient change curve of the differential pressure signal in the throat region of the differential pressure venturi flow meter, and simultaneously collects the temperature fluctuation amplitude of the corresponding section. Based on the preset differential pressure growth rate threshold and temperature offset range, it extracts the characteristic data of compressed bubble agglomeration. The disturbance suppression processing module performs frequency domain splitting on the characteristic data of compressed bubble agglomeration, extracts the high-frequency disturbance components in the differential pressure signal, processes the high-frequency disturbance components according to the preset amplitude attenuation coefficient, and constructs the suppressed differential pressure signal sequence. The density correction calculation module obtains the volumetric flow rate change gradient at the corresponding time based on the differential pressure signal sequence, establishes the coupling relationship between the differential pressure change rate and the volumetric flow rate offset, corrects the density distortion corresponding to abnormal compression according to the preset coupling deviation range, and outputs the corrected equivalent flow parameters. The gas-liquid ratio analysis module introduces the variation range of the gas phase compressibility elastic coefficient based on the corrected equivalent flow parameters, separates and calculates the gas compression contribution, removes the false density increment corresponding to the compression effect, and outputs the gas-liquid ratio information corresponding to the true distribution state. The flow dynamic compensation module uses gas-liquid ratio information to perform reverse mapping on the pressure difference growth rate threshold, establishes a correspondence between the intensity of compression behavior and the flow correction magnitude, and dynamically compensates the gas phase flow output value based on the correspondence to suppress the continuous underestimation deviation caused by bubble agglomeration compression.

Images