Vortex shedding flowmeter based on multi-parameter fusion and signal processing method

Abstract

The invention relates to the technical field of vortex shedding flowmeters, in particular to a vortex shedding flowmeter based on multi-parameter fusion and a signal processing method. A heating device is arranged at a vortex street sensor, and a first reference flow velocity is obtained by analyzing a heating temperature curve; arranging pressure sensors at the front and rear ends of the flowmeter, and calculating a second reference flow velocity according to the pressure difference and the fluid density; then, according to different flow velocity ranges, adaptively selecting a proper signal processing strategy, and carrying out fusion processing on the vortex street signal and the reference flow velocity; the detection sensitivity of a low-flow-velocity section is remarkably improved, the measurement stability of a high-flow-velocity section is enhanced, and high-precision measurement in a full-scale range is realized; and meanwhile, the measurement reliability is improved through a multi-parameter fusion mode, and the method has relatively high anti-interference capability and self-adaptive characteristic.

Description

Technical Field

[0001] The present application relates to the technical field of vortex flowmeters, and in particular to a vortex flowmeter based on multi-parameter fusion and a signal processing method. Background Art

[0002] With the development of industrial automation and precision control, flow measurement plays an increasingly important role in industrial production processes. As an important flow measurement instrument, vortex flowmeter is widely used in the measurement of industrial fluids such as compressed air and steam due to its high precision, simple structure and convenient maintenance.

[0003] Existing vortex flowmeters mainly use a measurement method based on the Karman vortex principle, which obtains fluid flow information by detecting the regular vortex generated when the fluid passes through a non-streamlined object immersed in the fluid. This measurement method is widely used in industrial sites and has the characteristics of high reliability and good stability.

[0004] However, under low flow rate conditions, the existing vortex flowmeter is difficult to accurately detect the flow rate due to the weak vortex signal, resulting in a high lower limit of the range; at the same time, when there is external vibration interference, the vortex signal of the existing vortex flowmeter is easily affected. Although it can be processed by filtering algorithm, it often reduces the system response speed and easily filters out effective small signals by mistake. This situation needs to be further improved. Summary of the invention

[0005] In order to solve the problem that the existing vortex flowmeter is difficult to accurately detect flow under low flow rate conditions or when there is external vibration interference, the present application provides a vortex flowmeter based on multi-parameter fusion and a signal processing method, which adopts the following technical solutions: In the first aspect, the present application provides a vortex flowmeter based on multi-parameter fusion, comprising: A pipe, through which the measured fluid flows; A vortex street sensor is arranged in the pipeline and is used to detect periodic vortex street pulse signals; A pressure sensor, comprising a first pressure sensor disposed at the front end of the pipeline and a second pressure sensor disposed at the rear end of the pipeline, wherein the first pressure sensor is used to detect the front end pressure and the second pressure sensor is used to detect the rear end pressure; a temperature sensor, disposed at the pipeline, is used to detect the current temperature; A heating device, arranged at the vortex street sensor, for generating a heating temperature curve; A signal processing unit is used to process the vortex pulse signal, the front end pressure, the rear end pressure, the current temperature and the heating temperature curve, and output a flow rate signal.

[0006] By adopting the above-mentioned technical scheme, in order to solve the problem that the vortex flowmeter has weak signals that are difficult to detect at low flow rates and the measurement accuracy is affected by vibration interference, the present application proposes a vortex flowmeter measurement scheme based on multi-parameter fusion, introduces the temperature curve generated by the heating device as a reference for the low flow rate segment, and uses the front and rear end pressure difference as the calibration basis for the high flow rate segment; specifically, a heating device is set at the vortex sensor, and a first reference flow rate is obtained by analyzing the heating temperature curve; a pressure sensor is set at the front and rear ends of the flowmeter, and a second reference flow rate is calculated based on the pressure difference and the fluid density; then, according to different flow rate ranges, a suitable signal processing strategy is adaptively selected to fuse the vortex signal with the reference flow rate; the detection sensitivity of the low flow rate segment is significantly improved, the measurement stability of the high flow rate segment is enhanced, and high-precision measurement within the full range is achieved; at the same time, the measurement reliability is improved by multi-parameter fusion, and it has strong anti-interference ability and adaptive characteristics.

[0007] Optionally, the signal processing unit includes: A density calculation module, used for calculating the density of the gas to be measured according to the rear end pressure and the current temperature; A first flow rate calculation module, used for calculating a first reference flow rate according to the heating temperature curve; A second flow rate calculation module, used for calculating a second reference flow rate according to the front end pressure, the rear end pressure and the measured gas density; The flow rate comprehensive processing module is used to calculate the final flow rate according to the first reference flow rate, the second reference flow rate, and the vortex pulse signal.

[0008] By adopting the above technical scheme, in order to solve the problem that the vortex flowmeter has weak signals and is easily interfered in the low flow velocity section, and the signal distortion in the high flow velocity section leads to a decrease in measurement accuracy; the density calculation module of the present application calculates the gas density based on the back-end pressure and temperature, and the first flow rate calculation module obtains the reference flow rate under the thermal diffusion characteristics through the heating temperature curve, and the second flow rate calculation module obtains another independent reference flow rate using the pressure difference principle. Finally, the flow rate comprehensive processing module intelligently selects the optimal measurement strategy according to the actual working conditions, which greatly expands the measurement range, improves the measurement reliability, realizes full-process adaptive signal processing, and improves the system response speed and anti-interference ability.

[0009] Optionally, the processing method of the flow rate comprehensive processing module includes: Setting a first threshold, a second threshold and a third threshold, wherein the second threshold is less than the first threshold, the first threshold is less than the third threshold, the second threshold is determined according to the minimum measurable flow velocity of the vortex flowmeter, the first threshold is determined according to the stability of the vortex signal, and the third threshold is determined according to the linearity of the vortex signal; When the first reference flow rate is less than a first threshold, taking the first reference flow rate as a final flow rate; When the first reference flow rate is less than a second threshold, setting the final flow rate to zero; When the first reference flow rate is greater than or equal to the first threshold value and less than a third threshold value, an expected vortex signal characteristic parameter is calculated according to the first reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameter to obtain a final flow rate; When the first reference flow rate is greater than or equal to the third threshold value, the expected vortex signal characteristic parameters are calculated according to the second reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameters to obtain the final flow rate.

[0010] By adopting the above-mentioned technical scheme, in order to solve the problem that the processing strategy is difficult to unify due to the significant differences in signal characteristics of the vortex flowmeter in different flow rate intervals, the present application realizes the precise switching of processing strategies by setting three key thresholds: the second threshold determines the zero flow judgment below the minimum measurable flow rate, the first threshold divides the measurement priority conversion point between the thermal method and the vortex method, and the third threshold identifies the critical value of the vortex signal entering the linear stability zone; the optimal processing strategy matching the signal characteristics is adopted in each interval: when it is lower than the second threshold, zero flow is directly judged, the second threshold to the first threshold is completely dependent on the thermal method measurement, the thermal measurement is used as a reference to optimize the vortex signal processing parameters between the first threshold and the third threshold, and the pressure difference signal is used as a reference to process the vortex signal after exceeding the third threshold. This not only solves the processing difficulties caused by the differences in signal characteristics in different flow rate intervals, but also realizes the closed-loop optimization of signal processing through the introduction of expected characteristic parameters, thereby improving the full-range measurement accuracy.

[0011] Optionally, the expected vortex signal characteristic parameters include: an expected signal frequency range, calculated according to the first reference flow velocity or the second reference flow velocity; An expected signal amplitude range is calculated based on the density of the gas being measured; The signal correction coefficient is calculated based on the pipeline diameter and the density of the measured gas.

[0012] By adopting the above technical scheme, when the gas conditions change frequently, the traditional fixed parameter signal processing method will cause signal distortion; the present application predicts the signal frequency range through the correspondence between the flow velocity and the Karman vortex street frequency to ensure the precise positioning of signal extraction; the signal amplitude range is predicted based on the correlation between the gas density and the vortex street strength to achieve adaptive adjustment of the amplification factor; a signal correction coefficient that takes into account the pipeline diameter and gas density is introduced to compensate for the nonlinear influence caused by the Reynolds number effect, which not only breaks through the limitations of the traditional fixed parameter processing method, but also realizes the precise adjustment of the processing parameters through the mapping relationship between physical quantities and signal characteristics, thereby improving the signal processing quality under complex conditions.

[0013] Optionally, the amplification and filtering process includes: Setting filter parameters according to the expected signal frequency range; Setting the amplifier gain according to the expected signal amplitude range; calibrating the signal according to the signal correction coefficient; Verify the validity of the processed signal.

[0014] By adopting the above technical solution, the present application utilizes the expected signal amplitude range to dynamically set the amplifier gain to avoid signal saturation or being too weak; compensates for nonlinear effects through signal correction coefficients, and finally verifies the effectiveness of the processing results by comparing the signal amplitude and frequency characteristics with the expected values. This not only solves the problem of poor adaptability of traditional fixed parameter processing methods, but also significantly improves signal quality through coordinated optimization of processing parameters.

[0015] Optionally, the heating device comprises: A heating element, comprising a heating coil wound on the vortex sensor, for heating the vortex sensor; a heat-insulating gasket, arranged at both ends of the heating element, for preventing the heat generated by the heating element from being conducted to the two ends; A heating control unit is used to control the heating element to generate the heating temperature curve according to the current temperature.

[0016] By adopting the above technical scheme, in order to solve the problems of low heat utilization efficiency and uneven temperature field distribution of the heating device in the existing vortex flowmeter, traditional technology often uses a simple heating plate or heating rod directly attached to the sensor surface. This method not only has an unsatisfactory heating effect, but also causes serious heat loss; the present application uses a heating coil directly wound on the surface of the vortex sensor to ensure the maximization of the heating area and the optimization of the heat conduction efficiency; insulating gaskets are set at both ends of the heating element to effectively prevent heat from diffusing to the non-measurement area; the current temperature is monitored in real time by the heating control unit and closed-loop control is performed to ensure the accuracy and repeatability of the heating temperature curve; the optimal thermal coupling between the heating element and the sensor is achieved, and the heat utilization efficiency is significantly improved; the heat flow guiding effect of the insulating gasket ensures the uniformity of the temperature field distribution in the measuring area; at the same time, a temperature closed-loop control mechanism is established to make the heating temperature curve have good dynamic response characteristics and temperature stability.

[0017] Optionally, also include: a signal anomaly detection module, configured to perform anomaly detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate; A data storage unit is used to store the abnormality detection result and the final flow rate.

[0018] By adopting the above technical solution, the present application establishes a signal anomaly detection module, and judges the consistency and reliability of the measurement results by analyzing the change trends of the three independent measurement results of the first reference flow rate, the second reference flow rate and the final flow rate; at the same time, a data storage unit is set to store key data such as the anomaly detection results and the final flow rate; real-time credibility evaluation of the measurement results is achieved, which significantly improves the reliability and safety of the system; through the accumulation and analysis of historical data, a basis is provided for predictive maintenance of the equipment; at the same time, a complete data management mechanism is established, which lays the foundation for the intelligent upgrade and remote monitoring of the flow meter.

[0019] In a second aspect, the present application provides a signal processing method for a vortex flowmeter based on multi-parameter fusion, and the method uses the vortex flowmeter based on multi-parameter fusion, comprising the following steps: Collect vortex pulse signal, front pressure, rear pressure, current temperature and heating temperature curve; Calculate the measured gas density according to the rear end pressure and the current temperature; Calculate a first reference flow rate according to the heating temperature curve; Calculate a second reference flow rate according to the front end pressure, the rear end pressure and the measured gas density; selecting a signal processing strategy according to the first reference flow rate; The vortex pulse signal is processed according to the selected signal processing strategy to obtain the final flow velocity.

[0020] Optionally, the signal processing strategy includes: When the first reference flow rate is less than a first threshold, directly using the first reference flow rate as the final flow rate; When the first reference flow rate is greater than or equal to the first threshold value and less than a third threshold value, performing signal processing according to the first reference flow rate and the measured gas density; When the first reference flow rate is greater than or equal to the third threshold, signal processing is performed according to the second reference flow rate and the measured gas density.

[0021] Optionally, also include: Performing abnormality detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate; When a signal anomaly is detected, switch to an alternate signal processing strategy; The anomaly detection results and the final flow rate are recorded.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application proposes a vortex flowmeter measurement scheme based on multi-parameter fusion, which introduces the temperature curve generated by the heating device as a reference for the low flow rate section, and uses the pressure difference between the front and rear ends as the calibration basis for the high flow rate section; specifically, a heating device is set at the vortex sensor, and a first reference flow rate is obtained by analyzing the heating temperature curve; a pressure sensor is set at the front and rear ends of the flowmeter, and a second reference flow rate is calculated based on the pressure difference and the fluid density; then, according to different flow rate ranges, a suitable signal processing strategy is adaptively selected to fuse the vortex signal with the reference flow rate; the detection sensitivity of the low flow rate section is significantly improved, the measurement stability of the high flow rate section is enhanced, and high-precision measurement within the full range is achieved; at the same time, the measurement reliability is improved by multi-parameter fusion, and it has strong anti-interference ability and adaptive characteristics; 2. In order to solve the problem that the vortex flowmeter has weak signals and is easily disturbed in the low flow rate section, and the signal distortion in the high flow rate section leads to decreased measurement accuracy; the density calculation module of the present application calculates the gas density based on the back-end pressure and temperature, the first flow rate calculation module obtains the reference flow rate under the thermal diffusion characteristics by heating the temperature curve, and the second flow rate calculation module obtains another independent reference flow rate by using the pressure difference principle. Finally, the flow rate comprehensive processing module intelligently selects the optimal measurement strategy according to the actual working conditions, which greatly expands the measurement range, improves the measurement reliability, realizes the full-process adaptive signal processing, and improves the system response speed and anti-interference ability; 3. The present application realizes precise switching of processing strategies by setting three key thresholds: the second threshold determines the judgment of zero flow below the minimum measurable flow rate, the first threshold divides the measurement priority conversion point between the thermal method and the vortex method, and the third threshold identifies the critical value of the vortex signal entering the linear stability zone; the optimal processing strategy matching the signal characteristics is adopted in each interval: zero flow is directly judged when it is lower than the second threshold, thermal measurement is completely relied on between the second threshold and the first threshold, thermal measurement is used as a benchmark to optimize the vortex signal processing parameters between the first threshold and the third threshold, and the vortex signal is processed based on the pressure difference signal after exceeding the third threshold. This not only solves the processing difficulties caused by the differences in signal characteristics in different flow rate intervals, but also realizes closed-loop optimization of signal processing through the introduction of expected characteristic parameters, thereby improving the full-range measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 2 It is an enlarged schematic diagram of part A in a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 3 It is a module schematic diagram of a signal processing unit in a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 4 It is a schematic diagram of a flow chart of comprehensive flow velocity processing in a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 5 It is a schematic diagram of characteristic parameters of expected vortex signal in a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 6 It is a schematic diagram of a module for amplification and filtering processing in a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Figure 7 It is a module schematic diagram of a vortex flowmeter signal anomaly detection based on multi-parameter fusion in an embodiment of the present application; Figure 8 It is a flow chart of a signal processing method of a vortex flowmeter based on multi-parameter fusion according to an embodiment of the present application; Fig. 9 It is a flow chart of a signal processing strategy in a signal processing method of a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application; Fig.10 It is a flow chart of anomaly detection in a signal processing method of a vortex flowmeter based on multi-parameter fusion in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to be used as limitations to the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of", "said", "above", "the" and "this" are intended to also include plural expressions, unless there is a clear indication to the contrary in the context. It should also be understood that the term "and / or" used in the present application refers to any or all possible combinations comprising one or more listed items.

[0025] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features, and in the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0026] The embodiments of the present application are further described in detail below in conjunction with the drawings in the specification.

[0027] In the first aspect, the present application provides a vortex flowmeter based on multi-parameter fusion, referring to Figure 1 and Figure 2 The vortex flowmeter includes a pipeline, a vortex sensor, a pressure sensor, a temperature sensor (not shown in the figure), a heating device and a signal processing unit (not shown in the figure), wherein the pipeline is used for the measured fluid to flow through; the vortex sensor is used to detect the periodic vortex pulse signal; the pressure sensor includes a first pressure sensor arranged at the front end of the flowmeter and a second pressure sensor arranged at the rear end of the flowmeter, the first pressure sensor is used to detect the front end pressure, and the second pressure sensor is used to detect the rear end pressure; the temperature sensor is used to detect the current temperature; the heating device is arranged at the vortex sensor, and is used to generate a heating temperature curve; the signal processing unit is used to process the vortex pulse signal, the front end pressure, the rear end pressure, the current temperature and the heating temperature curve, and output a flow rate signal.

[0028] Among them, the basic structure of the vortex flowmeter adopts the form of setting a vortex sensor in the pipeline. The pipeline adopts a standard flow measurement section, including an upstream straight pipe section and a downstream straight pipe section. The vortex sensor is set in the middle of the pipeline. The pressure sensors are installed at the standard pressure tapping positions of the upstream and downstream straight pipe sections respectively, and the temperature sensor can be installed in the downstream straight pipe section to accurately obtain the fluid parameters. The installation position of the triangular prism is located on the center line of the pipeline, so that the vortex generation area can cover the main flow field of the pipeline. The three top corners of the triangular prism can be chamfered. This design not only ensures the stability of vortex generation, but also avoids the flow field disturbance that may be caused by sharp corners.

[0029] Reference Figure 2The heating device includes a heating element, a thermal insulation gasket and a heating control unit (not shown in the figure). The heating element includes a heating coil wound on the vortex street sensor for heating the vortex street sensor; the thermal insulation gasket is arranged at both ends of the heating element for preventing the heat generated by the heating element from being conducted to the two ends; the heating control unit is used to control the heating element to generate a heating temperature curve according to the current temperature.

[0030] The heating device adopts coil heating, and the heating coil can be wound with nickel-chromium alloy wire, which has good heating uniformity and temperature stability. The heat insulation gasket can be made of high-temperature resistant mica sheets, which can effectively block the heat from spreading to both ends and ensure that the heating area is concentrated on the vortex sensor detection part. The heating control adopts a closed-loop control method to adjust the heating power by real-time monitoring of the temperature.

[0031] In one embodiment, referring to Figure 3 , the signal processing unit includes: The density calculation module is used to calculate the density of the measured gas based on the back-end pressure and current temperature.

[0032] Among them, this embodiment uses the ideal gas state equation as the basis and combines the gas compressibility factor for correction. The module receives the pressure signal from the back-end pressure sensor and the temperature signal from the temperature sensor, and eliminates the influence of temperature on the pressure sensor through the compensation algorithm to ensure the accuracy of the measurement data. The system has pre-established a database of physical property parameters of commonly used gases, including the basic physical property parameters of more than ten gases such as nitrogen, air, and natural gas.

[0033] Specifically, the density calculation uses the modified ideal gas state equation: ρ = P2 / (Z·R·T), where P2 is the rear end pressure, T is the current temperature, R is the gas constant, and Z is the compression factor. The compression factor Z is obtained by table lookup. The system stores the compression factor data table under different pressures and temperatures, and calculates the compression factor under the current working conditions by bilinear interpolation.

[0034] The first flow rate calculation module is used to calculate a first reference flow rate according to the heating temperature curve.

[0035] Among them, the first flow rate calculation module of this embodiment is based on the principle of heat transfer and calculates the flow rate by analyzing the changing characteristics of the heating temperature curve. The module controls the heating power through the heating device to form a stable temperature field on the surface of the vortex sensor. When the fluid flows through, it will take away a certain amount of heat, causing the temperature field to change. The fluid flow rate can be calculated by analyzing the temperature change rate.

[0036] Specifically, the flow rate is calculated using the heat balance equation: Q = h·A·(T W -T), where Q is the heating power, h is the convective heat transfer coefficient, A is the heat transfer area, TW is the wall temperature, and T is the fluid temperature. The convection heat transfer coefficient h shows a specific functional relationship with the flow rate. The corresponding relationship curve between h and flow rate is established through a large amount of experimental data. For example, in the case of a pipe diameter of DN50, when the heating power is 20W, the flow rate increases from 0.4m / s to 2m / s, and the wall temperature decreases from 60℃ to 45℃. The flow rate value can be inferred from this temperature change characteristic.

[0037] The second flow rate calculation module is used to calculate a second reference flow rate according to the front-end pressure, the rear-end pressure and the density of the measured gas.

[0038] Among them, the second flow rate calculation module of this embodiment is based on the pressure difference flow principle, and uses the front and rear pressure difference and density value to calculate the flow rate. The pressure difference before and after the fluid passes through the throttling device is measured by a high-precision pressure sensor, and the flow rate is calculated in combination with the real-time density value. The system can also consider the influence of the compressibility of the fluid and correct the calculation result by introducing the fluid expansion coefficient.

[0039] Specifically, the flow velocity is calculated using a modified form of the Bernoulli equation: Where C is the flow coefficient, ΔP is the pressure difference, and ρ is the density. The flow coefficient C is obtained through experimental calibration, and a relationship curve with the Reynolds number is established. For example, under the DN50 pipe diameter, the Reynolds number is 10 4 -10 5 In the range, the flow coefficient C is about 0.95-0.98, and the flow rate error calculated by this method is usually less than 1.5%.

[0040] The flow rate comprehensive processing module is used to calculate the final flow rate according to the first reference flow rate, the second reference flow rate and the vortex pulse signal.

[0041] Among them, the flow rate comprehensive processing module of this embodiment adopts a segmented processing strategy and selects a suitable signal processing method according to the different characteristics of the flow rate range. The module designs special signal processing operators for different flow rate intervals, including signal enhancement processing in low flow rate intervals, linear correction in medium flow rate intervals, and nonlinear compensation in high flow rate intervals.

[0042] Specifically, the module first performs spectrum analysis on the input vortex pulse signal to extract the main frequency and amplitude characteristics of the signal. In the low flow rate range, wavelet transform technology is used to improve the signal-to-noise ratio of the signal; in the medium flow rate range, the linear interpolation method is used to calculate the actual flow rate; in the high flow rate range, a nonlinear correction coefficient is introduced.

[0043] In one embodiment, referring to Figure 4 , the processing method of the flow rate comprehensive processing module includes: S410: Set a first threshold, a second threshold, and a third threshold.

[0044] Among them, the second threshold is smaller than the first threshold, the first threshold is smaller than the third threshold, the second threshold is determined according to the minimum measurable flow velocity of the vortex flowmeter, the first threshold is determined according to the stability of the vortex signal, and the third threshold is determined according to the linearity of the vortex signal.

[0045] In this embodiment, a three-level threshold control strategy is adopted, wherein the second threshold is set to 0.4m / s (minimum measurable flow velocity), the first threshold is set to 2m / s (vortex signal stability threshold), and the third threshold is set to 10m / s (vortex signal linearity threshold). The setting of these thresholds is based on the physical characteristics of the vortex flowmeter, especially considering the problem that the signal amplitude is too low and susceptible to vibration interference in the low flow velocity section.

[0046] Specifically, these thresholds are verified and determined in advance through a large amount of experimental data. For example, in the test, it was found that when the flow rate is lower than 2m / s, the amplitude of the vortex signal is significantly reduced, and the signal-to-noise ratio is not enough to support accurate measurement; when the flow rate is lower than 0.4m / s, it is difficult to obtain reliable measurement results even with heating. When the flow rate is above 10m / s, it is necessary to combine the pressure difference signal for correction to ensure measurement accuracy.

[0047] S420: When the first reference flow rate is less than the first threshold, use the first reference flow rate as the final flow rate.

[0048] Among them, when the flow velocity is less than 2m / s, this embodiment directly uses the first reference flow velocity obtained by the heating temperature method as the final flow velocity, avoiding the instability of the vortex signal in the low flow velocity section, and at the same time utilizing the good resistance to vibration interference of the heating measurement method.

[0049] Specifically, the system relies entirely on the heating temperature curve for flow velocity measurement within the flow velocity range of 0.4m / s to 2m / s. For example, when the flow velocity is 1.5m / s, the system only uses the temperature response data of the heating sensor to directly calculate the flow velocity through the heat transfer model, avoiding the use of vortex signals that may be interfered with.

[0050] S430: When the first reference flow rate is less than the second threshold, the final flow rate is set to zero.

[0051] Among them, this embodiment stipulates that when the first reference flow velocity is less than 0.4m / s, the system directly sets the flow velocity output to zero, taking into account the limit detection capability of the heating measurement method, and also to avoid false readings at extremely low flow rates.

[0052] Specifically, the system uses 0.4m / s as the zero point judgment threshold. When the flow rate measured by heating is detected to be lower than the threshold for 10 seconds, the output is reset to zero. For example, in industrial applications, when the flow rate drops from 0.5m / s to 0.3m / s, the system will reset the output to zero after confirming that the signal is stable, which can avoid the system outputting unreliable data at extremely low flow rates.

[0053] S440. When the first reference flow rate is greater than or equal to the first threshold value and less than the third threshold value, the expected vortex signal characteristic parameters are calculated according to the first reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameters to obtain the final flow rate.

[0054] Among them, this embodiment adopts a predictive signal processing method based on the first reference flow rate for the flow rate range of 2m / s to 10m / s. The system first calculates the expected vortex signal characteristics (frequency and amplitude) according to the first reference flow rate, pipeline diameter and fluid density, and then processes the actual vortex pulse signal in a targeted manner based on this.

[0055] Specifically, when the flow velocity is 5m / s, the system first calculates the expected vortex signal frequency (such as 50Hz) and amplitude (such as 20mV), then designs a bandpass filter with a bandwidth of 5Hz, and sets the amplifier gain to the inverse of the expected amplitude. The system will judge the frequency and amplitude of the actual vortex signal, and only consider the signal valid when the signal characteristics fall within the expected range (such as frequency error ±3%, amplitude error ±20%). This predictive processing method significantly improves the system's response speed and anti-interference ability.

[0056] S450. When the first reference flow rate is greater than or equal to the third threshold value, the expected vortex signal characteristic parameters are calculated according to the second reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameters to obtain the final flow rate.

[0057] In this embodiment, when the flow rate is greater than 10 m / s, the second reference flow rate (pressure difference method) is used as the prediction reference, and the expected vortex signal characteristic parameters are calculated based on this to achieve the processing of the vortex signal. This processing method takes into account the nonlinear characteristics that may appear in the vortex signal in the high flow rate section.

[0058] Specifically, for example, when the flow rate is 12m / s, the system first calculates the second reference flow rate based on the pressure difference signal, and then infers the expected vortex signal frequency (such as 120Hz) and amplitude characteristics, and designs the corresponding signal conditioning circuit parameters accordingly. The system uses adaptive gain control to appropriately reduce the amplification factor when the signal amplitude is large to avoid signal distortion. At the same time, the frequency detection bandwidth is expanded to ±5% to adapt to the changes in signal characteristics in the high flow rate section.

[0059] In one embodiment, referring to Figure 5 , the expected vortex signal characteristic parameters include: The expected signal frequency range is calculated according to the first reference flow rate or the second reference flow rate.

[0060] Among them, this embodiment calculates the expected signal frequency range through a vortex flowmeter. The system establishes an expected frequency calculation model based on the corresponding relationship between fluid flow rate, pipeline characteristic size and Strouhal number. The model takes into account the characteristics of different flow rate segments and uses a dynamic correction coefficient in the calculation to adapt to changes in actual working conditions.

[0061] Specifically, the expected signal frequency f = S t ×v / d, where S t is the Strouhal number (about 0.2-0.3), v is the reference velocity, and d is the characteristic size. For example, for a DN50 pipe, when the reference velocity is 5m / s, the expected frequency range is 20-30Hz; when the reference velocity is 8m / s, the expected frequency range is 32-48Hz.

[0062] The expected signal amplitude range is calculated based on the density of the gas being measured.

[0063] Among them, this embodiment establishes a functional relationship model between signal amplitude and gas density. The model is based on the principle of fluid dynamics and takes into account the effect of gas density on vortex shedding intensity. The system dynamically calculates the expected signal amplitude range by monitoring gas density in real time.

[0064] The signal correction coefficient is calculated based on the pipeline diameter and the density of the gas being measured.

[0065] Among them, this embodiment takes into account the characteristic differences of vortex street formation in pipes of different diameters and the influence of gas density on signal characteristics. The system pre-establishes a correction coefficient database, and obtains the correction coefficient under specific working conditions through table lookup and interpolation calculation.

[0066] In one embodiment, referring to Figure 6 , amplification and filtering processing includes: S610: Set filter parameters according to the expected signal frequency range.

[0067] S620: Set the amplifier gain according to the expected signal amplitude range.

[0068] S630: Calibrate the signal according to the signal correction coefficient.

[0069] S640: Verify the validity of the processed signal.

[0070] In one embodiment, referring to Figure 7 , also includes: The signal anomaly detection module is used to perform anomaly detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate.

[0071] Among them, this embodiment designs an anomaly detection method based on multi-source data fusion, and establishes an anomaly judgment criterion by analyzing the change trend and mutual relationship of the three flow rate signals. The system adopts sliding time window technology to monitor the change characteristics of flow rate data in real time. When an anomaly is detected, the relevant parameters are automatically recorded and an alarm is issued.

[0072] Specifically, the anomaly detection adopts a triple judgment mechanism: first, the change rate of the three flow velocity signals is calculated, and a primary warning is triggered when the change rate of any signal exceeds a preset threshold (such as 3% / s); secondly, the deviations between the signals are compared, and an intermediate warning is triggered when the deviation between the final flow rate and any reference flow rate exceeds 10%; finally, the fluctuation characteristics of the signal are analyzed. For example, an advanced warning is triggered when it is detected that the flow velocity fluctuation exceeds the set range within 5 seconds.

[0073] The data storage unit is used to store the anomaly detection results and the final flow rate.

[0074] Specifically, the system divides the data into three categories for storage: real-time flow rate data is stored at a frequency of 1 Hz, and records are kept for the past 7 days; abnormal event data contains complete process parameters and records are kept for the past 30 days; statistical analysis data (such as average flow rate per hour, standard deviation, etc.) are kept for the past 1 year.

[0075] In the second aspect, the present application provides a signal processing method for a vortex flowmeter based on multi-parameter fusion. The signal processing method for a vortex flowmeter based on multi-parameter fusion of the present application is described below in combination with the above-mentioned vortex flowmeter based on multi-parameter fusion.

[0076] Reference Figure 8 A signal processing method of a vortex flowmeter based on multi-parameter fusion is applied to the vortex flowmeter based on multi-parameter fusion, comprising the following steps: S810, collecting vortex pulse signals, front-end pressure, rear-end pressure, current temperature and heating temperature curve.

[0077] S820. Calculate the density of the gas to be measured according to the rear end pressure and the current temperature.

[0078] S830. Calculate a first reference flow rate according to the heating temperature curve.

[0079] S840: Calculate a second reference flow rate according to the front-end pressure, the rear-end pressure and the density of the gas being measured.

[0080] S850: Select a signal processing strategy according to the first reference flow rate.

[0081] S860. Process the vortex pressure pulse signal and the vortex velocity pulse signal according to the selected signal processing strategy to obtain a final flow velocity.

[0082] In one embodiment, referring to Fig. 9 , the signal processing strategies include: S910: When the first reference flow rate is less than the first threshold, directly use the first reference flow rate as the final flow rate.

[0083] S920: When the first reference flow rate is greater than or equal to the first threshold value and less than the third threshold value, perform signal processing according to the first reference flow rate and the measured gas density.

[0084] S930: When the first reference flow rate is greater than or equal to the third threshold, perform signal processing according to the second reference flow rate and the measured gas density.

[0085] In one embodiment, referring to Fig.10 , also includes: S1010, performing anomaly detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate.

[0086] S1020: When a signal abnormality is detected, switch to a backup signal processing strategy.

[0087] S1030. Record the abnormality detection result and the final flow rate.

[0088] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A vortex flowmeter based on multi-parameter fusion, characterized in that: include: A pipe, through which the measured fluid flows; A vortex street sensor is arranged in the pipeline and is used to detect periodic vortex street pulse signals; A pressure sensor, comprising a first pressure sensor disposed at the front end of the pipeline and a second pressure sensor disposed at the rear end of the pipeline, wherein the first pressure sensor is used to detect the front end pressure and the second pressure sensor is used to detect the rear end pressure; A temperature sensor, arranged at the pipeline, for detecting the current temperature; A heating device, arranged at the vortex street sensor, for generating a heating temperature curve; A signal processing unit is used to process the vortex pulse signal, the front end pressure, the rear end pressure, the current temperature and the heating temperature curve, and output a flow rate signal.

2. The vortex flowmeter based on multi-parameter fusion according to claim 1 is characterized in that: The signal processing unit comprises: A density calculation module, used for calculating the density of the gas to be measured according to the rear end pressure and the current temperature; A first flow rate calculation module, used for calculating a first reference flow rate according to the heating temperature curve; A second flow rate calculation module, used for calculating a second reference flow rate according to the front end pressure, the rear end pressure and the measured gas density; The flow rate comprehensive processing module is used to calculate the final flow rate according to the first reference flow rate, the second reference flow rate, and the vortex pulse signal.

3. The vortex flowmeter based on multi-parameter fusion according to claim 2 is characterized in that: The processing method of the flow rate comprehensive processing module includes: Setting a first threshold, a second threshold and a third threshold, wherein the second threshold is less than the first threshold, the first threshold is less than the third threshold, the second threshold is determined according to the minimum measurable flow velocity of the vortex flowmeter, the first threshold is determined according to the stability of the vortex signal, and the third threshold is determined according to the linearity of the vortex signal; When the first reference flow rate is less than a first threshold, taking the first reference flow rate as a final flow rate; When the first reference flow rate is less than a second threshold, setting the final flow rate to zero; When the first reference flow rate is greater than or equal to the first threshold value and less than a third threshold value, an expected vortex signal characteristic parameter is calculated according to the first reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameter to obtain a final flow rate; When the first reference flow rate is greater than or equal to the third threshold value, the expected vortex signal characteristic parameters are calculated according to the second reference flow rate and the measured gas density, and the vortex pulse signal is amplified and filtered according to the expected vortex signal characteristic parameters to obtain the final flow rate.

4. The vortex flowmeter based on multi-parameter fusion according to claim 3 is characterized in that: The expected vortex signal characteristic parameters include: an expected signal frequency range, calculated according to the first reference flow velocity or the second reference flow velocity; An expected signal amplitude range is calculated based on the density of the gas being measured; The signal correction coefficient is calculated based on the pipeline diameter and the density of the measured gas.

5. The vortex flowmeter based on multi-parameter fusion according to claim 4 is characterized in that: The amplification and filtering process includes: Setting filter parameters according to the expected signal frequency range; Setting the amplifier gain according to the expected signal amplitude range; calibrating the signal according to the signal correction coefficient; Verify the validity of the processed signal.

6. The vortex flowmeter based on multi-parameter fusion according to claim 1 is characterized in that: The heating device comprises: A heating element, comprising a heating coil wound around the vortex sensor, for heating the vortex sensor; Thermal insulation gaskets are arranged at both ends of the heating element to prevent the heat generated by the heating element from being conducted to the two ends; A heating control unit is used to control the heating element to generate the heating temperature curve according to the current temperature.

7. The vortex flowmeter based on multi-parameter fusion according to claim 2 is characterized in that: Also includes: a signal anomaly detection module, configured to perform anomaly detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate; A data storage unit is used to store the abnormality detection result and the final flow rate.

8. A signal processing method for a vortex flowmeter based on multi-parameter fusion, characterized in that: The vortex flowmeter based on multi-parameter fusion according to any one of claims 1 to 7 comprises the following steps: Collect vortex pulse signal, front pressure, rear pressure, current temperature and heating temperature curve; Calculate the measured gas density according to the rear end pressure and the current temperature; Calculate a first reference flow rate according to the heating temperature curve; Calculate a second reference flow rate according to the front end pressure, the rear end pressure and the measured gas density; selecting a signal processing strategy according to the first reference flow rate; The vortex pulse signal is processed according to the selected signal processing strategy to obtain the final flow velocity.

9. The signal processing method of vortex flowmeter based on multi-parameter fusion according to claim 8, characterized in that: The signal processing strategy includes: When the first reference flow rate is less than a first threshold, directly using the first reference flow rate as the final flow rate; When the first reference flow rate is greater than or equal to the first threshold value and less than a third threshold value, performing signal processing according to the first reference flow rate and the measured gas density; When the first reference flow rate is greater than or equal to the third threshold, signal processing is performed according to the second reference flow rate and the measured gas density.

10. The signal processing method of vortex flowmeter based on multi-parameter fusion according to claim 9, characterized in that: Also includes: Performing abnormality detection according to the change trends of the first reference flow rate, the second reference flow rate and the final flow rate; When a signal anomaly is detected, switch to an alternate signal processing strategy; The anomaly detection results and the final flow rate are recorded.

Images