Using stiffness measurement to compensate fluid property measurement

Abstract

To provide a meter electronics for using a stiffness measurement to compensate a fluid property measurement.SOLUTION: A meter electronics is provided, comprising an interface configured to communicatively couple to a sensor assembly and receive sensor signals from the sensor assembly, and a processing system communicatively coupled to the interface. The processing system is configured to determine a fluid property value based on the sensor signals and correct the fluid property value with a fluid property correction value, the fluid property correction value being correlated with a current stiffness value of the sensor assembly.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The embodiments described below relate to fluid property measurements, and more particularly to using stiffness to compensate fluid property measurements. [Background technology]

[0002] Vibrometers, such as Coriolis mass flow meters, liquid densitometers, gas densitometers, liquid viscometers, gas / liquid specific gravity meters, gas / liquid relative density meters, and gas molecular weight meters, are commonly known and used to measure fluid properties. Generally, a vibrometer comprises a sensor assembly and meter electronics. The material within the sensor assembly may be flowing or stationary. The vibrometer can be used to measure the mass flow rate, density, or other properties of the material within the sensor assembly.

[0003] Material enters the vibrometer through a pipeline connected to the inlet side of the vibrometer, is directed through a measurement conduit, and exits the vibrometer through the outlet side of the vibrometer. The pipeline can exert forces, known as flange loads, on the inlet and outlet of the vibrometer, which can affect the stiffness of the sensor assembly. During operation, the natural vibration modes of the vibrating system are defined in part by the combined mass of the measurement conduit and the material flowing within it.

[0004] When there is no flow through the vibrometer, the driving force applied to the measurement conduit causes all points along the measurement conduit to vibrate with the same phase or a small "zero offset," which is the time delay measured at zero flow rate. When material begins to flow through the vibrometer, Coriolis forces cause each point along the measurement conduit to have a different phase. For example, the phase at the inlet end of the vibrometer lags the phase at the center driver position, while the phase at the outlet leads the phase at the center driver position. Pickoffs on the measurement conduit generate sinusoidal signals representative of the motion of the measurement conduit. The signals output from the pickoffs are processed to determine the time delay between the pickoffs. The time delay between two or more pickoffs is proportional to the mass of material flowing through the measurement conduit. The meter electronics connected to the driver generate a drive signal to operate the driver and determine the mass flow rate and other properties of the material from the signal received from the pickoff.

[0005] Mass flow rate and other properties may be compensated for by using temperature measurements, pressure measurements, and / or estimates of flange loads on the sensor assembly. For example, mass flow rate can be calculated using a mass flow equation in which the tube, case, and fluid temperature values ​​are multiplied by constants, summed, and then multiplied by the uncompensated mass flow rate value. However, this requires temperature and pressure sensors and may not account for other conditions, such as flange loads, that may affect mass flow measurements. Similar issues can affect density measurements, as well as other fluid properties. Therefore, stiffness measurements must be used to compensate for fluid property measurements. Summary of the Invention

[0006] Meter electronics for compensating a fluid property measurement using a stiffness measurement is provided. In one embodiment, the meter electronics includes an interface communicatively coupled to a sensor assembly and configured to receive a sensor signal from the sensor assembly, and a processing system communicatively coupled to the interface. The processing system is configured to determine a fluid property value based on the sensor signal and to correct the fluid property value with a fluid property correction value, the fluid property correction value being correlated to a current stiffness value of the sensor assembly.

[0007] A method is provided for compensating fluid property measurements using stiffness measurements. According to one embodiment, the method includes determining a fluid property value of a fluid based on a sensor signal provided by a sensor assembly containing the fluid, and correcting the fluid property value with a fluid property correction value, the fluid property correction value being correlated to a current stiffness value of the sensor assembly.

[0008] [Aspect] According to one aspect, a meter electronics system for compensating a fluid property measurement using a stiffness measurement includes an interface communicatively coupled to a sensor assembly and configured to receive a sensor signal from the sensor assembly; and a processing system (602) communicatively coupled to the processing system (601). is configured to determine a fluid characteristic value based on the sensor signal and to correct the fluid characteristic value with a fluid characteristic correction value, the fluid characteristic correction value being correlated to a current stiffness value of the sensor assembly.

[0009] Preferably, the processing system (602) determines a current stiffness value of the sensor assembly (10). The method is further configured to:

[0010] Preferably, the processing system (602) converts the previously determined stiffness value of the sensor assembly into a The method is further configured to use the current stiffness value to correlate the fluid property correction value.

[0011] Preferably, the previously determined stiffness value is correlated with the fluid property correction value.

[0012] Preferably, the previously determined stiffness value is correlated with the fluid property correction value by using at least one of an empirical analysis and a computer model of the sensor assembly. Can.

[0013] Preferably, the fluid property correction value is correlated with the current stiffness value by using a previously determined stiffness versus fluid property relationship.

[0014] Preferably, the fluid property value is one of a mass flow rate value, a density value, a time delay value, a phase difference value, a resonant frequency value, and an oscillation period value.

[0015] Preferably, the fluid property correction value is a percentage error value.

[0016] Preferably, the current stiffness value is part of a modal relationship, the modal relationship being a relationship between two vibration modes. The relationship between the characteristics of the code.

[0017] According to one aspect, a method for compensating a fluid property measurement using a stiffness measurement includes determining a fluid property value of a fluid based on a sensor signal provided by a sensor assembly containing the fluid, and correcting the fluid property value with a fluid property correction value, the fluid property correction value being correlated to a current stiffness value of the sensor assembly.

[0018] Preferably, the method further comprises determining a current stiffness value of the sensor assembly.

[0019] Preferably, the method further comprises correlating the current stiffness value with the fluid property correction value using a previously determined stiffness value of the sensor assembly.

[0020] Preferably, the previously determined stiffness value is correlated with the fluid property correction value.

[0021] Preferably, the previously determined stiffness values ​​are determined based on empirical analysis and computer simulation of the sensor assembly. The fluid property correction values ​​are correlated by using at least one of the computer models. Can.

[0022] Preferably, the method further comprises correlating the fluid property correction value with the current stiffness value by using a previously determined stiffness to fluid property relationship.

[0023] Preferably, the fluid property value is one of a mass flow rate value, a density value, a time delay value, a phase difference value, a resonant frequency value, and an oscillation period value.

[0024] Preferably, the fluid property correction value is a percentage error value.

[0025] Preferably, the current stiffness value is part of a modal relationship, the modal relationship being a relationship between two vibration modes. The relationship between the characteristics of the code. [Brief explanation of the drawings]

[0026] Like reference numbers represent like elements in all drawings. It should be understood that the drawings are not necessarily to scale. [Figure 1] A vibrometer 5 for compensating fluid property measurements using stiffness measurements. [Figure 2] FIG. 2 is a block diagram of a vibration meter 5, including a block diagram representation of the meter electronics 20. [Figure 3] FIG. 1 is a block diagram of a vibrometer 5 having a notch filter according to an embodiment. [Figure 4A] 1 is a wireline diagram of a conduit, such as conduits 130, 130' described above, to illustrate vibration modes of the conduit. [Figure 4B] 1 is a wireline diagram of a conduit, such as conduits 130, 130' described above, to illustrate vibration modes of the conduit. [Figure 5A] 10 is a graph showing the correlation between error values ​​and stiffness values. [Figure 5B] 10 is a graph showing the correlation between error values ​​and stiffness values. [Figure 6] Meter electronics 20 for compensating fluid property measurements. [Figure 7] 7 is a method 700 for compensating fluid property measurements using stiffness measurements. DETAILED DESCRIPTION OF THE INVENTION

[0027] 1-7 and the following description illustrate specific examples to teach those skilled in the art how to make and use the best modes of embodiments for compensating for fluid property measurements using stiffness measurements. For the purpose of teaching the principles of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that are within the scope of the present description. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations for compensating for fluid property measurements using stiffness measurements. As a result, the embodiments described below are not limited to the specific examples described below, but only by the claims and their equivalents.

[0028] Figure 1 shows a vibrometer 5 for compensating fluid property measurements using stiffness measurements. As shown, the vibrometer 5 comprises a sensor assembly 10 and meter electronics 20. The sensor assembly 10 is responsive to the mass flow rate and density of the process material. Meter electronics 20 is connected to the sensor assembly 10 via leads 100 and outputs density, mass flow, and density data via port 26. and temperature information, as well as other information.

[0029] The sensor assembly 10 includes a pair of manifolds 150 and 150', a flange neck 110 and The conduits 130 and 130' include flanges 103 and 103' having flanges 103 and 103' with flanges 103 and 103', a pair of parallel conduits 130 and 130', a driver 180, a resistance temperature detector (RTD) 190, and a pair of pick-off sensors 170l and 170r. The conduits 130 and 130' have two essentially straight inlet sections 131, 131' and outlet sections 134, 134' that are angled toward each other in the conduit mounting blocks 120 and 120'. The conduits 130, 130' bend at two symmetrical locations along their length and converge along their length. The conduits 130, 130' are essentially parallel throughout their length. Brace bars 140 and 140' serve to define axes W and W' about which each conduit 130, 130' oscillates. Sections 131, 131' and 134, 134' of conduits 130, 130' are fixedly attached to conduit mounting blocks 120 and 120', which are fixedly attached to manifolds 150 and 150'. This provides a continuous, closed material path through sensor assembly 10.

[0030] When flanges 103 and 103', having holes 102 and 102', are connected via inlet end 104 and outlet end 104' to a process line (not shown) carrying the process material being metered, the material passes through orifice 101 in flange 103 into inlet end 104 of the meter and exits the manifold. The manifold 150 leads to a conduit mounting block 120 having a surface 121. Within the degasser 150, the material is split and sent through the conduits 130, 130'. The process material is then simply pumped through a block 120' having a surface 121' and a manifold 150'. The streams are recombined into a single stream which is then delivered to an outlet end 104' connected to a process line (not shown) by a flange 103' having holes 102'.

[0031] The conduits 130, 130' are selected to have substantially the same mass distribution, moment of inertia, and Young's modulus about bending axes W-W and W'-W', respectively, and are appropriately mounted in the conduit mounting blocks 120, 120'. These bending axes pass through the brace bars 140, 140'. Because the Young's modulus of the conduit changes with temperature, and this change affects flow rate and density calculations, an RTD 190 is attached to the conduit 130' to continuously measure the temperature of the conduit 130'. The temperature of the conduit 130', and therefore the temperature appearing at both ends of the RTD 190 for a given current passing through the RTD 190, is The voltage across the RTD 190 is governed by the temperature of the material passing through the conduit 130'. The temperature dependent voltage is used in a known manner by meter electronics 20 to compensate for changes in the modulus of elasticity of conduits 130, 130' due to changes in conduit temperature. RTD 190 is connected to meter electronics 20 by leads carrying RTD signal 195.

[0032] Both conduits 130, 130' are driven in opposite directions about their respective bending axes W and W' in what is referred to as the first out-of-phase bending mode of the flowmeter by driver 180. This driver 180 is connected to a magnet attached to conduit 130' and a magnet attached to conduit 130, This may comprise any one of a number of well known devices, such as opposing coils through which an alternating current is passed to vibrate both conduits 130, 130'. A suitable drive signal 185 is applied by meter electronics 20 via leads to driver 180.

[0033] Meter electronics 20 receives RTD signal 195 on lead 100 and sensor signal 165 appearing on lead 100, which carries left and right sensor signals 165l and 165r, respectively. Meter electronics 20 generates drive signal 185 appearing on lead 100 to driver 180, causing conduits 130 and 130' to vibrate. Meter electronics 20 processes left and right sensor signals 165l and 165r and RTD signal 195 to calculate the mass flow rate and density of material passing through sensor assembly 10. This information, along with other information, is applied as a signal on path 26 by meter electronics 20. A more detailed description of meter electronics 20 follows.

[0034] FIG. 2 shows a block diagram of the vibration meter 5, including a block diagram representation of the meter electronics 20. As shown, meter electronics 20 is communicatively coupled to sensor assembly 10. As previously described with reference to FIG. 1, sensor assembly 10 includes left and right pickoff sensors 170l, 170r, a driver 180, and an RTD 190, which communicate with a set of relays via communication channel 112. The device is communicatively coupled to meter electronics 20 via wire 100 .

[0035] Meter electronics 20 provides drive signal 185 over lead 100. More specifically, Meter electronics 20 provides drive signals 185 to drivers 180 within sensor assembly 10. Additionally, sensor signals 165, including left sensor signal 165l and right sensor signal 165r, are transmitted to the sensor assembly. More specifically, in the illustrated embodiment, the sensor signal 165 is , provided by left and right pickoff sensors 170l, 170r within sensor assembly 10. As can be seen, sensor signals 165 are provided to meter electronics 20 via communication channel 112, respectively.

[0036] The meter electronics 20 includes one or more signal processors 220 and one or more memory The processor 210 is communicatively coupled to the user interface 230. The processor 210 is also communicatively coupled to the interface 30. The processor 210 is also communicatively coupled to the communication port on port 26. The processor is communicatively coupled to the host via a power port 250. The processor 210 may be a microprocessor, although any suitable processor may be used. For example, the processor 210 may include sub-processors, such as a multi-core processor, The processor 210 may comprise a real communication port, a peripheral interface (e.g., a serial peripheral interface), on-chip memory, I / O ports, etc. In these and other embodiments, the processor 210 performs operations on received and processed signals, such as digitized signals. The system is configured to perform the calculation.

[0037] The processor 210 receives digitized sensor signals from one or more signal processors 220. The processor 210 can receive the phase difference, the temperature of the fluid in the sensor assembly 10, and the like. The processor 210 is also configured to provide information such as characteristics via a communication port. The processor 210 may also communicate with one or more memories 230 to receive and / or store information in the one or more memories 230. For example, the processor 210 may be configured to retrieve calibration functions from one or more memories 230. The calibration factor and / or sensor assembly zero (e.g., phase difference when the flow rate is zero) can be received. Each of the calibration factor and / or sensor assembly zero can be received by the vibration meter 5. and / or associated with the sensor assembly 10. The processor 210 uses the calibration coefficients to process the digitized signals received from the one or more signal processors 220. The received sensor signals can be processed.

[0038] The one or more signal processors 220 are shown as consisting of an encoder / decoder (CODEC) 222 and an analog-to-digital converter (ADC) 226. A plurality of signal processors 220 condition the analog signals and digitize the conditioned analog signals. The CODEC 222 may provide a filtered and / or digitized signal. The CODEC 222 is configured to receive the sensor signals 165 from the left and right pickoff sensors 170l, 170r. The CODEC 222 is also configured to provide a drive signal 185 to the driver 180. In some embodiments, more or fewer signal processors may be used.

[0039] As shown, the sensor signal 165 is provided to the CODEC 222 via a signal conditioner 240. The drive signal 185 is provided to the driver 180 via the signal conditioner 240. Although the signal conditioner 240 is shown as a single block, the signal conditioner 240 may be comprised of signal conditioning components such as two or more operational amplifiers, filters such as low-pass filters, and voltage-to-current amplifiers. For example, the sensor signal 165 may be amplified by a first amplifier, and the drive signal 185 may be amplified by a second amplifier. The signal may be amplified by a piezoelectric-to-current amplifier to ensure that the magnitude of the sensor signal 165 approaches the full-scale range of the CODEC 222.

[0040] In the illustrated embodiment, the one or more memories 230 are comprised of read-only memory (ROM) 232, random access memory (RAM) 234, and ferroelectric random access memory (FRAM®) 236. However, in alternative embodiments, the one or more memories 230 may be comprised of more or less memory. Alternatively, one or more memories 230 may be comprised of different types of memory (e.g., volatile, non-volatile, etc.). For example, instead of FRAM 236, erasable programmable RAM (RAM) may be used. Different types of non-volatile memory are used, such as programmable read-only memory (EPROM). The one or more memories 230 may be storage configured to store process data such as drive or sensor signals, mass flow or density measurements, etc.

[0041] The mass flow rate m' value can be determined according to the following formula:

number

[0042] With respect to the density measurement ρ, the resonant frequency at which each conduit 130, 130' vibrates may be a function of the square root of the spring constant of the conduit 130, 130' divided by the total mass of the conduit 130, 130' containing the material. The total mass of the conduit 130, 130' containing the material may be the mass of the conduit 130, 130' plus the mass of the material within the conduit 130, 130'. The mass of the material within the conduit 130, 130' is directly proportional to the density of the material. Therefore, the density of the material may be proportional to the square of the period at which the conduit 130, 130' containing the material vibrates multiplied by the spring constant of the conduit 130, 130'. Therefore, by determining the period at which the conduit 130, 130' vibrates, referred to herein as the period of vibration, and scaling the result appropriately, an accurate measurement of the density of the material contained within the conduit 130, 130' can be obtained. The meter electronics 20 can use the sensor signal 165 and / or the drive signal 185 to determine the period or resonant frequency. The vibration may be in the following vibration mode.

[0043] Due to changes in the stiffness of conduits such as conduits 130, 130' described above, the measured mass flow rate m' and The measured values ​​of mass flow rate m' and density ρ of the material are taken as The time delay Δt (or phase difference) between the sensor signals provided by the left and right pickoff sensors can also change over time. For example, as the temperature of the conduit increases, the stiffness of the conduit can increase accordingly. This increase in stiffness can change the time delay Δt (or phase difference) between the sensor signals provided by the left and right pickoff sensors. Increasing the stiffness of the conduit may also change the resonant frequency of the conduit.

[0044] As can be seen from equation [1] above, the mass flow rate m' can be measured more accurately by compensating for the time delay Δt (or phase difference) between the left and right sensor signals, or by compensating the mass flow rate m' measurement. Similarly, the density ρ can be measured more accurately by, for example, compensating for the resonant frequency (or oscillation period) measurement of one of the sensor signals. , or density ρ. While the above describes measuring time delay Δt, phase difference, mass flow rate m', resonant frequency, oscillation period, and density, other fluid property measurements such as viscosity, flow rate, etc. can be compensated for.

[0045] The measured fluid properties can be compensated for by measuring the stiffness of the sensor assembly. The stiffness of the sensor assembly can be pre-correlated with the fluid properties. For example, one or more stiffness values ​​of the sensor assembly, such as the conduit of the sensor assembly, can be used to compensate for the fluid properties. The value of the correction value may be pre-correlated with one or more correction values ​​associated with the value of the correction value. In an example, the plurality of stiffness values ​​may be pre-correlated with a plurality of mass flow m′ error values ​​or density ρ error values, as described in more detail below with reference to FIGS. 5A and 5B. The current stiffness value of the sensor assembly can be determined to be used to compensate the fluid property measurements, and the current stiffness value can be determined by any suitable technique.

[0046] In one exemplary technique, the current stiffness value of the sensor assembly determines the fluid property value. The sensor signal may be used to determine the density and current stiffness values. For example, the sensor signal may be used to determine the density and current stiffness values. This can be achieved by providing a drive signal having a resonant frequency component and some non-resonant frequency components. The sensor assembly can vibrate in response to these resonant and non-resonant frequencies. Thus, the pick-off sensor can provide a sensor signal made up of resonant and non-resonant frequency components corresponding to the resonant and non-resonant components of the drive signal, respectively. These resonant and non-resonant components are described in more detail below with reference to FIG. 3. As will be explained, the data may be filtered by a processing system to determine fluid property values ​​(eg, density values) and current stiffness values.

[0047] FIG. 3 shows a block diagram of a vibrometer 5 with a notch filter according to one embodiment. As shown, the vibrometer 5 is communicatively coupled to the sensor assembly 10. and meter electronics 20 configured to provide a multi-tone drive signal to sensor assembly 10. Sensor assembly 10 provides a sensor signal to meter electronics 20. Meter electronics 20 includes a drive circuit 322 and a demodulation filter 324 communicatively coupled to sensor assembly 10. Demodulation filter 324 is communicatively coupled to FRF estimation unit 325. Notch filter 326 is communicatively coupled to drive circuit 322 and the flow rate and and density measurement module 327. The notch filtered signal is and density measurement module 327 to determine the flow rate and / or density of the fluid in vibrometer 5.

[0048] The driver circuit 322 receives the resonant component of the sensor signal from the notch filter 326. The driver circuit 322 is configured to generate a multi-tone drive signal for the sensor assembly 10. The multi-tone drive signal is composed of a drive tone and a test tone. The drive tone is based on a resonant component provided by the notch filter 326. For example, the drive circuit 322 may include a feedback circuit that receives the resonant component and generates the drive tone by amplifying the resonant component. Other methods may also be used. The drive circuit 322 may generate a test tone at a resonant frequency. Test tones can also be generated at predetermined frequencies spaced apart from the number.

[0049] The demodulation filter 324 receives the sensor signal from the sensor assembly 10 and detects the presence of the signal in the sensor signal. For example, the drive tone and test tone in a multi-tone drive signal may induce intermodulation distortion signals in the sensor signal provided by the sensor assembly 10. To filter out the intermodulation distortion signals, the demodulation filter 324 generates a demodulation signal that includes the frequencies of the drive tone and test tone. The demodulation filter 324 may include a window or passband. The sensor assembly 10 provides a sensor signal comprised of resonant and non-resonant components corresponding to the test tone while preventing intermodulation distortion signals from impairing meter verification of the sensor assembly 10. Meter verification is performed using an FRF estimation unit 325, which estimates the frequency response of the test tone. The components of the signal are compared to the test tone to characterize the frequency response of the sensor assembly.

[0050] The notch filter 326 is used during meter verification, so normal flow and density During the measurement of the frequency, the notch filter 326 may not be switched in. Since there are large frequency changes, the coefficients of the notch filter 326 are frequently calculated and updated. Alternatively, when using meter verification, it may be necessary to sample the driving tone to determine the carrier frequency and calculate the coefficients of the notch filter 326 based on the determined carrier frequency. Then, the notch filter 326 is switched in and the test tone is increased to the desired amplitude. During meter verification, the carrier frequency may be monitored, and if the difference between the determined carrier frequency (determined during sampling of the driving tone as described above) and the carrier frequency during meter verification is greater than a threshold, the meter verification may, for example, switch notch filter 326 It can be ended by turning off the test tone.

[0051] To filter out the sensor signal component, the notch filter 326 is The notch filter 326 includes multiple stopbands centered at or near certain wavenumbers. The sensor signal components are attenuated or filtered out because they are concentrated at or near the frequencies of the stopbands. The resonant signal is passed because it is within the passband of the notch filter 326. However, the resonant signal is passed through the The notch filter may introduce a phase shift that may increase the overall phase delay of the drive feedback and may increase the overall complexity of the drive algorithm or circuitry that generates the drive tone, while also compensating for the phase shift when the notch filter 326 is switched in for meter verification. .

[0052] Alternatively, the stiffness value may be determined before the sensor signal is provided for fluid property measurement. For example, a meter verification routine can be performed before measuring a material with the sensor assembly. This may not require filtering out resonant components of the sensor signal.

[0053] In any of the above techniques, stiffness values ​​are determined using one or more vibration modes. That is, the stiffness value can be determined for a particular vibration mode or for two or more vibration modes. The various vibration modes will now be described with reference to Figures 4A and 4B.

[0054] [Vibration mode] 4A and 4B show wireline diagrams of a conduit to illustrate vibration modes of a conduit, such as conduits 130, 130' described above. As shown in FIGS. 4A and 4B, the conduit is The wireline 410 has a U-shape that represents a U-shaped conduit, which may be comprised of a left conduit and a right conduit. As shown in FIGS. 4A and 4B, the wireline 410 includes a left stationary wireline 412a and a right stationary wireline 412b. Also shown in FIGS. 4A and 4B are bending axes W-W, W'-W', which are co-located with the vibration nodes of the wireline 410. In FIG. 4A, The earline 410 includes a left primary bending mode wireline 414a and a right primary bending mode wireline 414b. 4B, the wireline 410 includes a left-handed torsional mode 418a and a right-handed torsional mode 418b. Also shown are a left-handed secondary bending mode wireline 416a and a right-handed secondary bending mode wireline 416b. In FIG. 4B, the wireline 410 includes a left-handed primary torsional mode 418a and a right-handed primary torsional mode 418b.

[0055] The left and right first bending mode wirelines 414a, 414b are shown by arrows to be 180 degrees out of phase, i.e., they move in opposite directions. This can be beneficial in various ways, such as reducing vibrations in the vibrometer caused by unequal displacements in the conduit. The left and right first bending mode wirelines 414a, 414b also align with bending axes W-W and W-W'. The left and right secondary bending modes are shown as having a single node at the same location. The earlines 416a, 416b are also 180 degrees out of phase with each other as indicated by the arrows. However, the left and right second-order bending mode wirelines 416a, 416b have two vibration nodes, hence the term "secondary." The natural frequencies of the left and right second-order bending mode wirelines 416a, 416b are higher than the natural frequencies of the left and right first-order bending mode wirelines 414a, 414b. The left-hand primary torsional mode 418a and the right-hand primary torsional mode 418b are shown as having asymmetric displacements along their respective lengths relative to the left and right stationary wirelines 412a, 412b. The arrows indicate that the left and right primary torsional modes 418a, 418b are out of phase with each other. vinegar.

[0056] The vibration modes represented by wireline 410 are shown as separate, but It can be superimposed on the conduit modeled by wireline 410: The conduit modeled by wireline 410 may have multiple vibration modes. For example, the left one of the conduits may have a first bending mode, a second bending mode, and a torsional mode. Thus, the conduit may have a first out-of-phase bending mode, a second out-of-phase bending mode, and a first torsional mode. The conduit may have higher order bending modes. modes (e.g., third, fourth, fifth, etc.), in-phase bending modes, and higher-order torsional modes (e.g., , 2nd, 3rd, 4th, etc.).

[0057] As indicated above, vibration modes can have shapes, amplitudes, and natural frequencies. The shapes of the vibration modes can be determined by comparing sensor signals, such as sensor signal 165, with one another. The phase difference between the sensor signal provided by left pickoff sensor 170l and the sensor signal provided by right pickoff sensor 170r can indicate torsional mode excitation caused by Coriolis forces due to flow through the vibrometer as the tubes vibrate in bending or other modes, and may be proportional to the phase difference between the conduits 130, 130'. The amplitude of the vibration mode may be proportional to the amplitude of the sensor signal 165.

[0058] The frequencies of the vibration modes can be determined from the sensor signal 165 and / or the drive signal 185. More specifically, the sensor signal 165 can have components corresponding to the vibration modes of the conduits 130, 130′ because each vibration mode has a natural mode frequency. Therefore, filtering can be used to separate the components and determine the frequency of each component. The frequency of each component corresponds to the frequency of a vibration mode. The frequencies of the vibration modes are sometimes individually referred to as modal frequencies. That is, the modal frequencies are the natural frequencies of the vibration modes, each corresponding to a component of the sensor signal 165 and / or drive signal 185.

[0059] As mentioned above, the vibration modes can be used to determine stiffness values. The bending modes can be used to determine stiffness values. Components of the sensor signal (i.e., bending mode response components) can be used together with the corresponding non-resonant components of the drive signal to determine stiffness values. However, if more than one mode is involved, may be used to determine the stiffness value.

[0060] For example, the component of the sensor signal associated with the first torsional mode is treated as the bending mode response component. can be used together to determine the current stiffness value, which is determined by the value of the time delay Δt The mass flow rate m' can be affected by both modes. Thus, for example, compensating a measurement of mass flow rate m' using the ratio of the first bending mode stiffness to the first torsional mode stiffness may be more accurate than a measurement of mass flow rate that is compensated using only the first bending mode stiffness.

[0061] Additionally or alternatively, the stiffness value of one of the vibration modes may be adjusted to the stiffness of another of the vibration modes. For example, stiffness values ​​can be determined from the first bending mode and vibration values ​​can be determined from the first torsional mode. This can be beneficial because using torsional modes to determine stiffness can be prohibitively expensive in terms of computational requirements, etc.

[0062] The sensor signal provided by the pickoff sensor is provided to a mode filter, which generates a first-order It is possible to determine the bending mode stiffness value, the first torsion mode resonance frequency, etc. Specifically, a modal filter may emphasize or de-emphasize a sensor signal associated with a mode shape, thereby enabling the frequency, amplitude, and / or phase associated with the mode shape to be quantified. For example, a modal filter may emphasize or de-emphasize a sensor signal associated with a mode shape, thereby enabling the frequency, amplitude, and / or phase associated with the mode shape to be quantified. The RPO sensor signal is weighted by 0.5. The weighted LPO and RPO sensor signals may be summed. The resulting signal, which is a weighted average signal of the LPO and RPO sensor signals, is a first-order out-of-phase bending mode. The harmonics induce in-phase LPO and RPO sensor signals, thus emphasizing the first-order out-of-phase bending mode. Because the first torsional mode induces LPO and RPO sensor signals that are 180° out of phase, the resulting signals also tend to de-emphasize the first torsional mode.

[0063] In contrast, to highlight the first-order out-of-phase torsional mode, One of them may be phase shifted by 180° before being added. As an example, the LPO sensor signal The LPO and RPO sensor signals can each be multiplied by 0.5 to provide weighted LPO and RPO sensor signals. The weighted LPO sensor signal is phase shifted by 180°. This phase-shifted and weighted LPO sensor signal may be summed with the weighted RPO sensor signal. The resulting signal, which is a weighted average signal of the relatively phase-shifted LPO and RPO sensor signals, can be seen to have a first order phase shift. The flexural modes tend to be emphasized and the first-order out-of-phase bending modes de-emphasized.

[0064] Thus, for example, to determine the torsional mode frequency, weighted average filtering of the relatively phase-shifted LPO and RPO sensor signals can be used to provide a weighted average signal of the relatively phase-shifted LPO and RPO sensor signals. The frequency of the weighted average signal of the relatively phase-shifted LPO and RPO sensor signals can be measured to determine the first torsional mode frequency. The stiffness of the first bending mode can be determined as described above. For example, a weighted average of the LPO and RPO sensor signals can be used for the demodulation described with reference to FIG. The signal may be provided to a filter 324 .

[0065] As can be understood from the foregoing discussion, vibration modes may be related. For example, the relationship between two vibration modes, referred to herein as a modal relationship, may be based on the phase, amplitude, and / or frequency of the two vibration modes, which may be characteristics of the two vibration modes. In one example, the modal relationship is the frequencies of the left and right second-order bending mode wirelines 416a, 416b. It may be the difference between the vibration frequencies of the left and right first bending mode wirelines 414a and 414b. The relationship may be quantified as a modal difference, a ratio, or any other suitable value. For example, the modal relationship may be the difference between the time period of the left and right second-order bending mode wirelines 416a, 416b and the time period of the left and right first-order bending mode wirelines 414a, 414b.

[0066] The current stiffness value may be used alone or as part of a relationship between, for example, the first out-of-phase torsional mode frequency and the stiffness of the first out-of-phase bending mode, where the current stiffness value is the stiffness of the first out-of-phase bending mode. That is, the current stiffness value may be part of a modal relationship, such as a ratio, difference, etc., between the first torsional mode frequency and the first out-of-phase bending mode stiffness. The following may be associated with the first-order out-of-phase bending mode and are part of the mode relationship: The present invention indicates that a current stiffness value, which may be absent, is used in conjunction with a previously determined correlation between one or more stiffness values ​​and one or more fluid property values ​​to compensate the fluid measurements.

[0067] [Correlation between stiffness and fluid properties] 5A and 5B are graphs illustrating the correlation between error values ​​and stiffness values. As shown in FIG. 5A, the error values ​​are mass flow error values, and in FIG. 5B, the error values ​​are density error values. The graphs in FIGS. 5A and 5B are mass flow error graph 500A and density error graph 500B, respectively. Mass flow error graph 500A and density error graph 500B include stiffness shift axes 510A and 510B and mass flow error axes 520A and density error axes 520B, respectively, which are unitless and expressed as percentages. Although percentages are shown, any suitable values ​​and units may be used, including non-percentage values.

[0068] As shown, the stiffness shift may be of the drive mode stiffness, i.e., the stiffness value is determined using the drive mode or the first out-of-phase bending mode described above with reference to FIG. 4A. However, any suitable vibration mode or stiffness may be used. The percentages may also correspond to values ​​determined at nominal conditions, such as nominal temperature, fluid pressure, and flange load. The nominal conditions may be those at the time of calibration of the vibrometer.

[0069] For example, the stiffness shift in Figures 5A and 5B can be defined by equation [2]:

number

[0070] The mass flow error graph 500A and density error graph 500B also show a mass flow error plot 530A and a density error plot 530B, both of which range from about -15% to about 7% along the stiffness shift axes 510A, 510B. 5A and 5B, respectively. Mass flow error plot 530A ranges from approximately 15% to -6% along mass flow error axis 520A. Density error plot 530B ranges from approximately 0.9% to approximately -0.4% along density error axis 520B. However, any suitable plot for the other fluid property axes may be used. Ranges, units, and ratios may be used. Mass flow error plot 530A and density error plot 530B may be determined by linear interpolation of mass flow error and density error values ​​determined for various stiffness values, denoted as stiffness shift values. That is, mass flow error plot 530A and density error plot 530B are correlations between fluid property values ​​and stiffness values ​​of the sensor assembly.

[0071] The correlation between the fluid property value and the stiffness value may be a stiffness-to-fluid property relationship, such as a linear relationship. For example, the correlation between the fluid property value and the stiffness value may be represented by a linear relationship having a slope and an intercept, such that a linear relationship exists between the fluid property value and the stiffness value. For example, the linear relationship may be described by Equation [3]:

number

[0072] 5A and 5B, the fluid property measurements are represented by mass flow error values ​​540A and density error values ​​540B shown as discrete plots. The mass flow error values ​​540A and density error values ​​540B may be simulated, for example, via a finite element method (FEM) that simulates the effects of varying the temperature, pressure, and / or flange load of the sensor assembly. Mass flow error value 540A and density error value 540B may also be determined by empirical methods in which stiffness values ​​are measured simultaneously with the mass flow and density measurements.

[0073] Mass flow error value 540A and density error value 540B may correspond to nominal mass flow and density values, respectively. That is, mass flow and density values ​​determined under various process conditions that vary the stiffness of the sensor assembly. Mass flow error value 540A and density error value 540B may be determined by subtracting the mass flow and density values ​​determined at nominal conditions by the mass flow and density values ​​determined at nominal conditions and dividing the results by the mass flow and density values ​​determined at nominal conditions, respectively.

[0074] As described above, there is a linear relationship between the mass flow error values ​​540A and density error values ​​540B and their corresponding stiffness values. The mass flow error plot 530A and density error plot 530B may be generated by linear interpolation from the mass flow error values ​​540A and density error values ​​540B, respectively. However, any suitable plot may be generated by any suitable means, such as, for example, extrapolation, using non-linear fitting, etc.

[0075] As can be seen from the above discussion, stiffness values ​​can be correlated with fluid property values ​​regardless of what causes the stiffness of the vibrometer to change, thereby allowing the fluid property measurements to be compensated regardless of process conditions that may cause the fluid property measurements to be inaccurate, as described in more detail below.

[0076] Mass flow error plot 530A, density error plot 530B, mass flow error value 540A, and density error value 540B may be previously determined correlations between one or more stiffness values ​​of the sensor assembly and one or more corresponding fluid property values. For example, a table relating mass flow error value 540A to stiffness values ​​may be stored, e.g., in meter electronics 20 described above. Similarly, a table relating density error value 540B to corresponding stiffness values ​​may be stored, e.g., in meter electronics 20 described above. Additionally or alternatively, mass flow error plot 530A and density error plot 530B may be stored in meter electronics, e.g., in the form of an equation that can be used to determine a mass flow error value or a density error value from a current stiffness value.

[0077] Thus, when the process material is subsequently measured by the sensor assembly and a current stiffness value for the sensor assembly is also determined, the correlation can be used to compensate the mass flow and / or density measurements. For example, the current stiffness value can be input into an equation representing the mass flow error plot 530A to determine a corresponding mass flow error value, which can be used to compensate the mass flow value determined from the sensor signal provided by the sensor assembly.

[0078] Thus, mass flow error plot 530A, density error plot 530B, mass flow error values ​​540A, and density error values ​​540B correlate one or more stiffness values ​​with fluid property correction values. As noted, the fluid property correction values ​​are percent error values, i.e., the fluid property correction values ​​are expressed as errors relative to a nominal value. The percentage error values ​​can be obtained directly from the mass flow error values ​​540A and density error values ​​540B, or from the mass flow error plot 530A and density error plot 530B. The mass flow error value and density error value can be indirectly determined by interpolation, such as output 530B.

[0079] The current stiffness value can be determined simultaneously with the fluid property measurement or can be previously determined. That is, the current stiffness value can be determined from the same sensor signal as the fluid property measurement or can be determined before the fluid property measurement. In the latter scenario, the current stiffness value can be determined from the sensor signal while the sensor assembly is subjected to known process conditions, such as temperature, pressure, and flange load. These values ​​can be assumed to be the same when measuring the fluid property. For example, the temperature, pressure, and / or flange load can be assumed to be constant throughout a series of fluid property measurements.

[0080] Mass flow error plot 530A, density error plot 530B, mass flow error value 540A, and / or density error value 540B may be a correlation between a previously determined stiffness value and a fluid property correction value. For example, the current stiffness value may be correlated with the mass flow error value of mass flow error plot 530A by comparing the current stiffness value with the previously determined stiffness value of mass flow error plot 530A and determining the corresponding mass flow error value. The mass flow error value may be used as a fluid property correction value to correct the mass flow value calculated according to equation [1] above. Similar corrections can be made using density error plot 530B. These and other values ​​may be stored in meter electronics 20 for compensating fluid measurements, as described in more detail below.

[0081] [Meter electronics for compensating fluid property measurements] FIG. 6 illustrates meter electronics 20 for compensating fluid property measurements. As shown in FIG. 4, meter electronics 20 includes an interface 601 and a processing system 602. Meter electronics 20 receives a vibration response, such as from sensor assembly 10. Meter electronics 20 processes the vibration response to obtain flow properties of the flow material flowing through sensor assembly 10.

[0082] The interface 601 can receive the sensor signal 165 from one of the pickoff sensors 170l, 170r shown in Figures 1 and 2. The interface 601 can perform any necessary or desired signal conditioning, such as any manner of formatting, amplification, buffering, etc. Alternatively, some or all of the signal conditioning can be performed in the processing system 602. Additionally, the interface 601 can provide a connection between the meter electronics 20 and an external device. The interface 601 can be any type of electronic, optical, or The interface 601 may be based on vibration response. The interface 601 may be coupled to a digitizer, such as the CODEC 222 shown in Figure 2, where the sensor signal comprises an analog sensor signal. The digitizer samples and digitizes the analog sensor signal to generate a digitized sensor signal.

[0083] The processing system 602 performs the operations of the meter electronics 20 and processes the flow rate from the sensor assembly 10. Processing Measurements. The processing system 602 executes one or more processing routines to process the flow measurements to generate one or more flow characteristics. The system 602 is communicatively coupled to the interface 601 and receives information from the interface 601. is configured to receive.

[0084] Processing system 602 may be a general purpose computer, a microprocessing system, a logic circuit, or any Additionally or alternatively, the processing system 602 may be distributed among multiple processing devices. System 602 may also include any type of integrated or stand-alone electronic storage medium, such as storage system 604 .

[0085] The storage system 604 stores flow meter parameters and data, software routines, and In one embodiment, the storage system 604 can store data, constant values, and variable values, for the processing system 602, such as the operation routine 610 and the compensation routine 620 of the vibrometer 5. The storage system may also store statistics such as standard deviations, confidence intervals, etc.

[0086] The operational routine 610 measures the fluid properties of the fluid and communicates with a sensor, such as the sensor assembly 10 described above. The operational routine 610 can perform the functions necessary to determine the current stiffness value of the sensor assembly. For example, the operational routine 610 can determine the time delay between the LPO and RPO sensor signals, measure the frequency of the LPO or RPO sensor signals, etc.

[0087] Thus, the operating routine 610 may be configured to calculate fluid properties such as time delay or phase difference, resonant frequency, etc. A value 612 can be determined. The fluid property value can also be a mass flow value, a density value, etc. The operational routine 610 can store the fluid property value in fluid property value 612. The operational routine 610 can also determine a current stiffness value 614 of the sensor assembly. For example, the operational routine 610 can simultaneously determine the current stiffness value 614 and the fluid property value 612, as described above with reference to FIG. 3.

[0088] The compensation routine 620 may, for example, determine a mass flow error value from the current stiffness value. The compensation routine 620 may compensate for a fluid property value, such as a mass flow rate value, by calculating a mass flow error value. That is, the mass flow error value may be a fluid property compensation value. Other compensation values ​​may be used, and may have units other than a percentage error value. Thus, the compensation routine 620 may compensate for a fluid property compensation value. The correlation between the mass flow error value and the current stiffness value can be used to correct the fluid property value. As an example, the mass flow value may be corrected by adjusting the mass flow value using the mass flow error value.

[0089] The processing system 602 can therefore store the correlation 630. As shown in FIG. Thus, correlation 630 includes stiffness value 632, correction value 634, and relationship 636. Correlation 630 is The stiffness values ​​632 and the correction values ​​634 may be correlated in any suitable manner. The current stiffness value may be correlated with a fluid property correction value stored or determined from the correction values ​​634 by using the stiffness value of the stiffness values ​​632 or a stiffness value determined from the stiffness values ​​632. Therefore, the stiffness value 632 may be a predetermined stiffness value. It is part of the modal relationships, such as the relationship between the stiffness of the bending mode and the frequency of the first bending mode. The current stiffness value may be calculated using, for example, the previously determined stiffness versus fluid property in relationship 636. An exemplary stiffness vs. fluid property relationship may be the stiffness shift vs. fluid property error in equation [3] above. , any suitable stiffness versus fluid property relationship may be used.

[0090] [method] FIG. 7 illustrates a method 700 for compensating fluid property measurements using stiffness measurements. As shown, method 700 begins in step 710 by determining a fluid property value based on a sensor signal. The sensor signal may be provided by the sensor assembly 10 described above, although any suitable sensor assembly may be used. The fluid property value may be a mass flow rate value, a density value, a time delay or phase difference, a resonant frequency of the sensor assembly, etc. In step 720, method 700 corrects the fluid property value with a fluid property correction value. The fluid property correction value may be correlated to a current stiffness value of the sensor assembly.

[0091] The method 700 can also determine the current stiffness value of the sensor assembly. The method 700 may use, for example, a sensor signal provided by a sensor assembly to determine the current stiffness. The current stiffness value may be part of a modal relationship. Additionally or alternatively, the method 700 may use a fluid property value determined and stored before the fluid property value is determined. However, the current stiffness value may nevertheless be determined by retrieving a stored current stiffness value that is an accurate measurement of the stiffness of the sensor assembly. For example, the current stiffness value may be determined by determining the stiffness value of the sensor assembly under process conditions immediately before the fluid is measured to determine the fluid property value. Thereafter, the process conditions, such as temperature, pressure, etc., remain constant, thereby ensuring that the current stiffness value is accurate.

[0092] The method 700 uses a previously determined stiffness value of the sensor assembly to calculate a current stiffness value. It may also be correlated with fluid property correction values. For example, the method 700 may read or calculate previously determined stiffness values ​​and fluid property correction values ​​from the stiffness values ​​632 and correction values ​​634. The previously determined stiffness value and fluid property correction value may be correlated, for example, as described above with reference to FIGS. 5A and 5B. The current stiffness value may be compared to the previously determined stiffness value to determine whether the fluid property correction value can be used to correct the fluid property value. For example, if the current stiffness value is within a range of the previously determined stiffness values, the fluid property correction value that correlates with the previously determined stiffness value may be used. Thus, the current stiffness value may be correlated with the fluid property correction value.

[0093] As described above, the previously determined stiffness values ​​of the sensor assembly, the fluid property correction values, and the correlation between the previously determined stiffness values ​​and the fluid property correction values ​​are calculated in step 710. The stiffness may be determined by using empirical analysis or computer modeling of the same sensor assembly as the sensor assembly providing the sensor signal, a similar sensor assembly having the same or similar design, etc. A current stiffness value is determined for the sensor assembly measuring the fluid to determine the fluid property value to be corrected. The correlation between the previously determined stiffness value and the fluid property correction value may be via a table of values, a formula, etc.

[0094] The vibrometer 5, meter electronics 20, and method 700 described above can use stiffness measurements to compensate for fluid property measurements. Thus, a small number of sensors, such as temperature sensors, pressure sensors, etc., may be used. More specifically, because the current stiffness value of the sensor assembly depends on the temperature of the sensor assembly, the pressure of the fluid measured by the sensor assembly, etc., the current stiffness value may compensate for the fluid property value without using temperature, pressure, or other non-stiffness values ​​of the fluid and / or sensor assembly.

[0095] Additionally, because the current stiffness value depends on various process conditions, a single correlation between the previously determined stiffness value and the fluid property correction value may be used, i.e., instead of multiple correlations between temperature, pressure, and other process conditions and the fluid property correction value, one correlation may be used. Only a correlation may be necessary. This can simplify and reduce the calculations required to compensate the fluid property measurements. Thus, the processing system 602 can be more efficient. The processing system 602 can operate more efficiently, freeing up more computing resources for other tasks, thereby increasing the capabilities of the processing system 602.

[0096] Furthermore, correcting the fluid property value with the current stiffness value may be more accurate than using temperature and / or pressure sensors. For example, the current stiffness value may depend on the flange load applied to the sensor assembly. The flange load may not be measured accurately and may change significantly over time. Because the current stiffness value depends on the flange load, a correlation between the current stiffness value and the fluid property correction value may be more accurate than, for example, an estimate of the flange load and a correlation of that estimate to the fluid property correction value. Therefore, operation of the vibrometer 5 may be advantageous by providing more accurate fluid property measurements. This will improve the situation.

[0097] The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the present description. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments can be combined or excluded in various ways to create further embodiments, and that such further embodiments are within the scope and teachings of the present description. It will also be apparent to those skilled in the art that the above-described embodiments can be combined, in whole or in part, to create additional embodiments within the scope and teachings of the present description.

[0098] Thus, while specific embodiments have been described herein for illustrative purposes, those skilled in the art will recognize that various equivalent modifications are possible within the scope of the present disclosure. The teachings provided herein may be applied to the embodiments described above and illustrated in the accompanying figures, as well as other meter electronics, vibrometers, and methods for compensating fluid property measurements using stiffness measurements. Accordingly, the scope of the above-described embodiments should be determined from the following claims.

Claims

1. 1. Meter electronics (20) for compensating fluid property measurements using stiffness measurements, comprising: an interface (601) configured for the meter electronics (20) to communicatively couple to the sensor assembly (10) and receive a sensor signal from the sensor assembly (10); and, a processing system (602) communicatively coupled to the interface (601); Equipped with The processing system (602) determines a fluid property value based on the sensor signal, and Meter electronics (20) configured to correct the characteristic value with a fluid characteristic correction value, the fluid characteristic correction value being correlated to a current stiffness value of the sensor assembly.

2. The processing system (602) determines the current stiffness value of the sensor assembly (10). The meter electronics (20) of claim 1, further configured to:

3. The processing system (602) uses a previously determined stiffness value of the sensor assembly.

3. The meter electronics of claim 1, further configured to correlate the current stiffness value with the fluid property correction value.

4. 4. The method of claim 3, wherein the previously determined stiffness value is correlated with the fluid property correction value. Electronic equipment (20).

5. The previously determined stiffness value is correlated with the fluid property correction value by using at least one of an empirical analysis and a computer model of the sensor assembly. The meter electronics (20) of claim 4.

6. 6. The meter electronics (20) of any one of claims 1 to 5, wherein the fluid property correction value is correlated with the current stiffness value by using a previously determined stiffness versus fluid property relationship.

7. The meter electronics (20) of any one of claims 1 to 6, wherein the fluid property value is one of a mass flow rate value, a density value, a time delay value, a phase difference value, a resonant frequency value, and an oscillation period value.

8. The meter electronics (20) of any one of claims 1 to 7, wherein the fluid property correction value is a percentage error value.

9. The current stiffness value is a part of a modal relationship, and the modal relationship is a characteristic of two vibration modes. The meter electronics (20) of any one of claims 1 to 8, wherein the meter electronics (20) is intergender.

10. 1. A method for compensating fluid property measurements using stiffness measurements, the method comprising: determining a fluid property value of a fluid based on a sensor signal provided by a sensor assembly containing the fluid; and correcting the fluid property value with a fluid property correction value, the fluid property correction value being correlated to a current stiffness value of the sensor assembly.

11. The method of claim 10 , further comprising determining the current stiffness value of the sensor assembly.

12. A previously determined stiffness value of the sensor assembly is used to calculate the current stiffness value of the flow.

12. The method of claim 10 or claim 11, further comprising correlating with a body characteristic correction value.

13. The method of claim 12 , wherein the previously determined stiffness value is correlated with the fluid property correction value.

14. The previously determined stiffness value is correlated with the fluid property correction value by using at least one of an empirical analysis and a computer model of the sensor assembly. The method of claim 13,

15. 15. The method of claim 10, further comprising correlating the fluid property correction value with the current stiffness value by using a previously determined stiffness to fluid property relationship.

16. 16. The method of claim 10, wherein the fluid property value is one of a mass flow rate value, a density value, a time delay value, a phase difference value, a resonant frequency value, and an oscillation period value.

17. 17. The method of any one of claims 10 to 16, wherein the fluid property correction value is a percentage error value.

18. The current stiffness value is a part of a modal relationship, and the modal relationship is a characteristic of two vibration modes.

18. The method of any one of claims 10 to 17, wherein the relationship is between the sexes.

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