JP6080880B2 - Method and apparatus for measuring fluid parameters with a vibrometer - Google Patents

Description

  The present invention relates to a flow meter, and more particularly to a method and apparatus for measuring fluid parameters with a vibratory flow meter.

Flow meters are used to measure mass flow, density, and other properties of fluid materials. The fluid material may include a liquid, a gas, a suspended substance in the liquid or gas, or any combination thereof. Vibrating conduit sensors, such as Coriolis mass flow meters and vibration densitometers, generally operate by detecting the movement of a vibrating tube containing fluid material. Properties related to the material in the conduit, such as mass flow, density, etc. can be determined by processing measurement signals received from motion transducers related to the conduit. The vibration mode of a system filled with vibrating material is generally affected by the combined mass, stiffness, and damping characteristics of the enclosing conduit and the material contained therein.

A typical Coriolis mass flow meter is connected in series to a pipeline or other transport system, and includes one or more conduits that carry materials such as fluids, slurries, etc., in the system. Each conduit is considered to have a set of natural vibration modes including, for example, simple bending, twisting, radial and coupled modes. In a typical Coriolis mass flow measurement application, as material flows through the conduit, the conduit is excited in one or more vibration modes, and the movement of the conduit is measured at points away along the conduit.
The excitation is usually provided by an actuator, which is an electromechanical device such as a voice coil type driver that periodically perturbs the conduit. The mass flow rate is determined by measuring the time delay between movements or the phase difference between movements at the position of the transducer.
The density of the fluid material can be determined from the frequency of the vibration response of the flow meter. Two such transducers (or pickoff sensors) are commonly used to measure the vibration response of the fluid conduit and are usually located upstream and downstream of the actuator.
The two pickoff sensors are typically connected to the electronics by a cable that is a pair of two separate wires. The electronics receives the signals from the two pickoff sensors and processes the signals to derive a flow measurement.

ここで、
ω＝角度振動周波数
ｄ＝流体管の内径
ｃ＝処理流体の音速 One possible source of vibration flow meter error is caused by a compression rate known as the sound velocity effect. These errors increase with increasing tube vibration frequency, so errors often occur during operation at high frequencies. A number of models have been developed to clarify the sound velocity effect of vibratory flow meters. For example, the effect of errors in measured density and mass flow rate is determined by the error theory of Coriolis flowmeters due to measured fluid compressibility, HempJ and Kutin J. “Flow measurement and measurement” 17: 359-369 (2006). It was made clear as follows.

here,
ω = angular vibration frequency d = inner diameter of fluid pipe c = sonic velocity of processing fluid

Thus, if the speed of sound in the processing fluid is known, the measured density and mass flow error can be determined and corrected. Prior art solutions have generally addressed situations where the process fluid comprises a mixture having two or more phases and the speed of sound of the individual phases is known. For example, PCT International Publication No. WO2009 / 017494 , assigned to the assignee of the present application, discloses a method for determining the sound speed of an element for a mixture of multiphase flows based on a known sound speed, which is hereby incorporated by reference. The subscription to
It should be understood that, similar to the formula provided in the above referenced PCT publication , the above formula is merely an example model of the VOS effect on a vibrating tube. Other models are known and are within the specification and claims. The specific examples described above and the examples used throughout should not limit the scope of the invention.

Aspect According to one aspect of the invention, a method for calculating a fluid parameter of a fluid flowing through at least a first vibratory flow meter includes the following steps:
Vibrating the flow meter at one or more frequencies;
Receiving a vibration response;
Generating a first fluid characteristic of the fluid;
Generating at least a second fluid property of the fluid;
Calculating a fluid parameter based on the first fluid characteristic and at least the second fluid characteristic.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate.
Preferably, the step of vibrating the vibratory flow meter includes the following steps:
Vibrating the vibratory flow meter at a first frequency;
Furthermore, it has the process of vibrating a vibration type flow meter with the at least 2nd frequency which is a frequency different from a 1st frequency.

Preferably, the method further comprises the step of separating the vibration response into a first frequency component of the vibration response and at least a second frequency component of the vibration response.
Preferably, the first fluid characteristic is based on a first frequency component of the vibration response and at least the second fluid characteristic is based on at least a second frequency component of the vibration response.
Preferably, the step of vibrating the vibration type flow meter includes:
Vibrating the vibratory flow meter at a first frequency;
Separating the vibration response into a first frequency component and at least a second frequency component, wherein the first frequency component and at least the second frequency component are generated by vibration at the first frequency.

Preferably, the method further comprises the following steps;
Vibrating at least the second vibratory flow meter;
Generating a first fluid characteristic from a first vibratory flow meter;
Generating at least a second fluid characteristic from at least a second vibratory flow meter.
Preferably, the step of vibrating the first vibrometer and at least the second vibrometer comprises:
Vibrating the first vibrometer at a first frequency;
Oscillating at least the second flow meter at at least a second frequency different from the first frequency.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement generated from a known fluid density.

Preferably, the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, and
Comparing the first density measurement with the predicted density measurement;
Determining that the first density measurement includes an actual fluid density if the difference between the first density measurement and the predicted density measurement is less than a threshold value.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate, and
Comparing the first mass flow rate to the predicted mass flow rate;
Determining that the first mass flow rate includes an actual mass flow rate if the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold value.

Preferably, the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, and
Comparing the first density measurement with the predicted density measurement;
If the difference between the first density measurement and the predicted density measurement exceeds a threshold, the method includes calculating the actual fluid density and the sound velocity of the fluid.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate, and
Comparing the first mass flow rate to the predicted mass flow rate;
If the difference between the first mass flow rate and the predicted mass flow rate exceeds a threshold, the method includes calculating the actual mass flow rate and the sound velocity of the fluid.

Preferably, the fluid parameter includes density.
Preferably, the fluid parameter includes mass flow rate.
Preferably, the fluid parameter includes the speed of sound of the fluid.
Preferably, the method further comprises calculating a density error based on the calculated sound speed.
Preferably, the method further comprises correcting the density based on the calculated density error.
Preferably, the method further includes calculating a mass flow error based on the calculated sound velocity.
Preferably, the method further includes correcting the mass flow based on the calculated mass flow error.
Preferably, the method further includes comparing the calculated sound speed with the predicted sound speed and determining an error condition if the difference between the calculated sound speed and the predicted sound speed exceeds a threshold.

According to another aspect of the present invention, in a vibratory flow meter for calculating fluid parameters of a flow fluid, comprising a meter assembly including a vibration sensor and meter electronics coupled to the vibration sensor.
The meter electronics receives the vibration response from the vibration sensor,
Generating a first fluid property of the fluid;
Generating at least a second fluid property of the fluid;
A fluid parameter is configured to be calculated based on the first fluid characteristic and at least the second fluid characteristic.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate.
Preferably, the first fluid characteristic is based on a first frequency component of the vibration response and at least the second fluid characteristic is based on at least a second frequency component of the vibration response.

Preferably, the meter electronics is further configured to vibrate the vibratory flow meter at a first frequency and at least a second frequency, wherein at least the second frequency is different from the first frequency.
Preferably, the meter electronics is further configured to separate the vibration response into a first frequency component and at least a second frequency component.
Preferably, the meter electronics is further configured to vibrate the flowmeter at a first frequency and to isolate the vibration response into a first frequency component and at least a second frequency component, wherein the first frequency component and At least the second frequency component is generated by vibration at the first frequency.
Preferably, the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, wherein the first density measurement is generated from a known fluid density.

Preferably, the first fluid characteristic and at least the second fluid characteristic include a first density measurement and at least a second density measurement, and the meter electronics further compares the first density measurement with the predicted density. If the difference between the first density measurement and the predicted density is less than a threshold value, the first density measurement is configured to determine that it comprises an actual density.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow, and the meter electronics further includes a predicted mass flow and the first mass flow. In comparison, if the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold value, the first mass flow rate is configured to comprise an actual mass flow rate.

Preferably, the fluid parameter includes density.
Preferably, the fluid parameter includes mass flow rate.
Preferably, the fluid parameter includes the speed of sound of the fluid.
Preferably, the meter electronics is further configured to calculate a density error based on the calculated sound speed.
Preferably, the meter electronics is further configured to correct the density based on the density error.
Preferably, the meter electronics is further configured to calculate a mass flow error based on the calculated sound velocity.
Preferably, the meter electronics is further configured to correct the mass flow based on the mass flow error.
Preferably, the meter electronics is further configured to compare the calculated sound speed with the predicted sound speed and determine an error if the difference between the calculated sound speed and the predicted sound speed exceeds a threshold value. Yes.

In accordance with another aspect of the present invention, a fluid flow fluid comprising a first flow meter, at least a second flow meter, and a processing system coupled to the first flow meter and at least the second flow meter. The vibratory flow meter system that calculates the parameters
Processing system
Receiving a first vibration response from a first flow meter, receiving at least a second vibration response from at least a second flow meter;
Generating a first fluid characteristic of the fluid based on the first vibration response;
Generating at least a second fluid characteristic of the fluid based on at least the second vibrational response;
A fluid parameter is configured to be calculated based on the first fluid characteristic and at least the second fluid characteristic.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate.

Preferably, the processing system is further configured to vibrate the first flow meter at the first frequency and vibrate at least the second flow meter at at least the second frequency, wherein the at least second frequency is at the first frequency. Is different from the frequency.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement, wherein the first density measurement is generated from a known fluid density.
Preferably, the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, the processing system further comprising:
Comparing the first density measurement with the predicted density measurement, and if the difference between the first density measurement and the predicted density measurement is less than a threshold value, the first density measurement includes the actual fluid density Is configured to determine.

Preferably, the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, the processing system further comprising:
Comparing the first density measurement with the predicted density measurement and, if the difference between the first density measurement and the predicted density measurement exceeds a threshold, configured to calculate the actual fluid density and the sound velocity of the fluid. Has been.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate, the processing system further comprising:
Comparing the first mass flow rate with the predicted mass flow rate;
If the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold, the first mass flow rate is configured to comprise an actual mass flow rate.
Preferably, the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate, the processing system further comprising:
Comparing the first mass flow rate with the predicted mass flow rate;
If the difference between the first mass flow rate and the predicted mass flow rate exceeds a threshold value, the actual mass flow rate and the sound velocity of the fluid are calculated.

Preferably, the fluid parameter includes density.
Preferably, the fluid parameter includes mass flow rate.
Preferably, the fluid parameter includes the speed of sound.
Preferably, the processing system is further configured to calculate a density error based on the calculated sound speed.
Preferably, the processing system is further configured to correct the density based on the calculated density error.
Preferably, the processing system is further configured to calculate a mass flow error based on the calculated speed of sound.
Preferably, the processing system is further configured to correct the mass flow based on the mass flow error.
Preferably, the processing system is further configured to compare the calculated sound speed with the predicted sound speed and to determine an error if the difference between the calculated sound speed and the predicted sound speed exceeds a threshold value. .

FIG. 1 shows a vibrometer with a flow meter assembly and meter electronics. FIG. 2 is a flowchart of a method for calculating the speed of sound in a fluid flow, according to an embodiment of the present invention. FIG. 3 shows a circuit for generating a first frequency and at least a second frequency according to an embodiment of the present invention. FIG. 4 shows details of the Hilbert transform block according to an embodiment of the present invention. FIG. 5 is a block diagram of an analysis block according to an embodiment of the present invention. FIG. 6 shows a circuit for generating a first frequency and at least a second frequency according to an embodiment of the present invention. FIG. 7 illustrates a vibratory flow meter system for calculating the speed of sound in a fluid flow, according to an embodiment of the present invention. FIG. 8 is a flowchart of a method for calculating the speed of sound in a fluid flow according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 1-8 and the following description describe specific examples and disclose to those skilled in the art how to make and use the best mode of the present invention. For the purpose of disclosing the inventive principle, some conventional aspects are simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art can combine the features described below in various ways to form numerous variations of the present invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

  FIG. 1 shows a vibrometer 5 comprising a flow meter assembly 10 and meter electronics 20. Meter electronics 20 is connected to meter assembly 10 via lead 100 and provides one or more of density, mass flow rate, mass flow sum, temperature, speed of sound, viscosity, phase component and other information on communication path 26. It is configured to give a measurement result. It will be apparent to those skilled in the art that the present invention can be used with any type of Coriolis flow meter regardless of the number of drivers, pickoff sensors, flow conduits, or vibration modes of operation. Further, it will be appreciated that the flow meter 5 may alternatively include a vibratory flow meter that does not have the mass flow measurement capability of a Coriolis flow meter, such as a vibratory density meter.

The flow meter assembly 10 includes a pair of flanges 101, 101 ′, manifolds 102, 102 ′, vibratory sensors including drivers 104 and pickoff sensors 105, 105 ′, and flow conduits 103 A and 103 B. Driver 104 and pickoff sensors 105, 105 ′ are connected to flow conduits 103A and 103B.
The flanges 101 and 101 ′ are attached to the manifolds 102 and 102 ′. Manifolds 102 and 102 ′ are attached to the other end of spacer 106. The spacer 106 maintains the spacing of the manifolds 102, 102 'to prevent unwanted vibrations in the flow conduits 103A and 103B. When the flow meter assembly 10 is inserted into a conduit system (not shown) that carries the measured flow material, the flow material enters the flow meter assembly 10 through the flange 101 and the total amount of flow material is flow conduit 103A. And 103B through the inlet manifold 102, flow through the flow conduits 103A and 103B, return to the outlet manifold 102 'and exit the meter assembly 10 through the flange 101'.

The flow conduits 103A and 103B are selected to have approximately the same mass distribution, moment of inertia, and elastic modules about the bending axes WW and W′-W ′, respectively, and the inlet manifold 102 and outlet manifold 102 ′. It is attached properly. The flow conduits 103A and 103B extend outwardly from the manifolds 102, 102 'in a generally parallel manner.
The flow conduits 103A and 103B are driven in opposite directions around the respective bending axes W and W ′ by the driver 104 and are driven into the so-called first out-of-phase bending mode of the flow meter 5. Driver 104 comprises one of the well known configurations such as a magnet attached to flow conduit 103A and a coil attached to flow conduit 103B oppositely. The alternating current vibrates both conduits through opposing coils. Appropriate drive signals are applied by meter electronics 20 to driver 104 via leads 110.

The meter electronic device 20 can generate a drive signal at a predetermined frequency. Meter electronics 20 can generate drive signals at varying frequencies, including generating multiple superposition frequencies.
Meter electronics 20 receives sensor signals on leads 111 and 111 ', respectively. Meter electronics 20 generates a drive signal on lead 110 and driver 104 flows to vibrate conduits 103A and 103B. The meter electronics 20 generates a left / right speed signal from the pickoff sensors 105, 105 ′ and calculates a mass flow rate. In some embodiments, meter electronics 20 processes the signal received from driver 104 to calculate the mass flow rate. The communication path 26 provides input and output means so that the meter electronics 20 can interface with an operator or other electronic system. FIG. 1 is shown merely as an example of the operation of a Coriolis flow meter and is not intended to limit the disclosure of the present invention.

  Conveniently, commercially available low frequency vibratory flow meters can accurately measure density and the adverse effects from sound speed are not excessive. Accordingly, as is known in the art, the density obtained from a low frequency vibratory flow meter can generally be assumed to include an accurate value. Conversely, a high frequency meter can be used to accurately measure the vibration frequency of the meter, but suffers from further errors caused by the sound velocity effect of the density measurement result.

  FIG. 2 shows a flowchart 200 of a method for calculating fluid parameters of a fluid according to an embodiment of the present invention. Fluid parameters include, but are not limited to, the speed of sound, mass flow rate or density. The following description often refers to fluid parameters including the speed of sound. It will be understood that this is an example and that the invention is not limited to the specific embodiments described. At step 201, the flow meter assembly of the vibratory flow meter is vibrated. This embodiment of the invention requires only one vibratory flow meter. The flow meter assembly can be oscillated at one or more frequencies.

  In one embodiment of the invention, the flow meter assembly is oscillated at a drive frequency of one. A drive frequency generates a vibration response that includes a first frequency component and at least a second frequency component such that vibration of the meter assembly at the one drive frequency produces multiple frequency response components. For example, noise generated by the flow through the flow meter generally generates vibrations in the flow meter assembly at at least a second frequency. At least the second frequency is generally a different frequency than the first frequency. At least the second frequency component of the vibration response has a smaller amplitude than the first frequency component. However, at least the second frequency component is amplified and processed. The first vibration frequency response and at least the second vibration frequency response can then be processed in the following steps.

In another embodiment, the flow meter assembly of one flow meter is oscillated at a first drive frequency and oscillated at least at a second drive frequency. At least the second drive frequency is different from the first drive frequency. According to an embodiment of the present invention, the first drive frequency includes a low frequency and at least the second frequency includes a higher frequency. It should be understood that one vibratory flow meter needs to be calibrated for both the first drive frequency and at least the second drive frequency. One vibratory flow meter can be calibrated using, for example, both air and water. The first and second drive frequencies generate a vibration response that includes a first frequency component and at least a second frequency component. It should be understood that more vibration response can be obtained if more drive frequencies are used. Thus, in some embodiments, two or more frequencies are used to increase the accuracy of the calculated fluid parameters.

In another embodiment of the invention, the flow meter assembly is vibrated at a first drive frequency and then at least at a second drive frequency. Alternatively, the flow meter is vibrated simultaneously at both the first drive frequency and at least the second drive frequency. This is achieved by including a mixture of two or more frequencies if the drive signal is often followed. As a result, the vibrational response of the flow meter includes at least two frequency components.
In all embodiments, one vibratory flow meter generates a vibration response. In some embodiments, the vibration response includes a first frequency component and at least a second frequency component. However, it should be understood that even if the vibratory flow meter is vibrated only at a high drive frequency, the vibration response includes only one frequency component. The vibration response can then be processed in the following steps.

  At step 202, a vibration response is received from one vibratory flow meter. The vibration response may be received from pickoff sensors 105A, 105B, or driver 104. The vibration response includes a first frequency component and at least a second frequency component. At least the second frequency component includes a frequency different from the first frequency component. For example, as described above, at least the second frequency component includes a higher frequency than the first frequency component. The vibration response is processed to obtain a first frequency component and at least a second frequency component. The processing includes separating the vibration response into a first frequency component and at least a second frequency component. The processing includes separating the vibration response into a first frequency component and at least a second frequency component, for example by using a bandpass filter.

At step 203, a first fluid characteristic is generated. The first fluid properties include density, mass flow rate, volumetric flow rate, viscosity and others. This list is not comprehensive and experts in the art readily recognize additional fluid properties that can be generated. The following description refers to the first fluid property and should not limit the scope of the invention in any way as it only includes density measurements for purposes of clarity. In accordance with one embodiment of the present invention, the first density measurement is generated using a first frequency derived from a first frequency component. In accordance with another embodiment of the invention, the first density measurement is generated from a stored or known density value. In accordance with an embodiment of the present invention, the first density measurement is assumed to include the actual density of the flow material. It should be understood that the term “actual” density refers to the density obtained if there is no sound speed error. Thus, although the actual density word is used, the actual value calculated still contains errors introduced by other variables and thus varies from the true density. When the first frequency measurement includes the actual density when the first frequency is sufficiently low and the sound speed effect that produces an error in the density measurement is relatively small and therefore has very little, if any, influence. This assumption is generally accurate. However, in some applications this is not a realistic assumption. Thus, the first density measurement is compared, for example, with a predicted density stored or obtained from a look-up table and discarded if the difference between the first density measurement and the predicted density measurement exceeds a threshold value. . Alternatively, if the difference between the first density measurement and the predicted density measurement exceeds a threshold, multiple equations rather than one equation are used to calculate the speed of sound. This is explained in more detail below.
The threshold value may be a stored value or a value input from a user / worker. Alternatively, the threshold may be based on the user / operator's desire for accurate measurements. Further, the predicted density can be a stored value or a value input from a user / operator. Alternatively, the predicted density can be based on previous measurements. In other embodiments, the first density measurement may be generated from a stored value or a known value. In other words, the first density measurement need not be generated from the first frequency component.

ここで、β＝ρ_{ａｃｔｕａｌ}/ｃ^２である。 In step 204, at least a second fluid characteristic is generated. At least the second fluid characteristic includes density, mass flow rate, volume flow rate, viscosity, and the like. This list is not comprehensive and experts in the art readily recognize additional fluid properties that can be generated. At least the second fluid property may include the same fluid property as the first fluid property, or may include a different fluid property. At least the second fluid property is described as including only density measurements for purposes of clarity and should not limit the scope of the invention in any way. In accordance with an embodiment of the present invention, at least a second density measurement may be generated using at least a second frequency of at least a second frequency component. As described above, according to an embodiment of the present invention, the second frequency is a different frequency than the first frequency. Thus, the first density measurement and at least the second density measurement are different due to vibrating the flow material at different frequencies and the resulting sound velocity effect. For example, this is true when the first density measurement includes the actual density, the second density measurement is obtained at a higher frequency, and the density measurement includes an error due to the sound velocity effect. These differences can be used to determine various fluid parameters using various models. The fluid parameter can include, for example, the speed of sound, density, or mass flow rate. It should be understood that the models provided below are merely examples, and experts in the art will readily recognize a variety of additional models that can measure additional fluid parameters. One example model is provided in Equation (3).

Here, β = ρ _actual / c ² .

ここで、β＝ｍ_{ａｃｔｕａｌ}/ｃ^２である。従って、マトリックス(４)がマトリックス(３)と同様に用いられ得る。 Various fluid parameters are determined using a matrix as shown in equation (3). The specific number of fluid parameters determined depends, for example, on the number of vibration frequencies used. In a given matrix, each frequency at which the flow meter vibrates can present other equations. The description is limited to using the first density measurement and at least the second density measurement to determine the actual density and the speed of sound of the fluid, but the flowmeter is vibrated at more frequencies, or others It should be understood that other fluid parameters can be determined using only a mathematical model of For example, in some embodiments, density measurements do not provide an appropriate solution when the fluid includes a gas. However, mass flow measurement presents an appropriate solution. Thus, rather than using density measurements, mass flow measurements can be used based on equation (2). This results in the model shown in equation (4).

Here, β = m _actual / c ² . Thus, matrix (4) can be used in the same manner as matrix (3).

ここで、
ρ_{ｆｉｒｓｔ}＝第１の密度測定
ρ_{ｓｅｃｏｎｄ}＝第２の密度測定
ω_{ｓｅｃｏｎｄ}＝少なくとも第２の周波数
ｄ＝流れ導管１０３Ａ及び１０３Ｂの内径
ｃ＝流れ材料の音速 In step 205, fluid parameters of the flow material are determined based on the first density measurement and at least the second density measurement. In accordance with an embodiment of the present invention, the fluid parameter may include, for example, the speed of sound. The following description often refers to fluid parameters as including only the speed of sound as an example. Therefore, the present invention should not be limited to sound speed calculation. In accordance with an embodiment of the present invention, the speed of sound of the flow material can be determined using equation (5).

here,
ρ _first = first density measurement ρ _second = second density measurement ω _second = at least second frequency d = inner diameter of flow conduits 103A and 103B c = velocity of flow material

According to an embodiment of the present invention, if the first density measurement is considered to include the actual density, that is, if the difference between the first density measurement and the predicted density measurement is within a threshold value, Equation (5) is used on its own to solve the sound velocity of the flow material. As described above, in some embodiments, the first density measurement is generated based on a known or stored density measurement. Thus, the first density measurement need not be generated based on the first frequency component of the vibration response. The first density measurement is input by a user / operator or read from a memory or the like. All matters in equation (5) except for the speed of sound can be measured using the first frequency component and at least the second frequency component as described above. Accordingly, the speed of sound of the flow material can be calculated based on a first density measurement obtained from the first frequency and at least a second density measurement obtained from at least the second frequency. With the first and at least second density measurements, the speed of sound can be calculated using a single vibratory flow meter without the need for an external measuring device as in the prior art. Alternatively, two or more flow meters can be used as follows. Equation (5) can be used whenever desired, but the most accurate calculation is obtained when the difference between the first density measurement and the actual density of the fluid is within a threshold. As noted above, this is a reasonable assumption if the sound speed effect does not produce significant errors in the density obtained at the first frequency. Furthermore, equation (5) is merely an example of one model, and other models are contemplated and are within the scope of the present invention. Thus, other fluid parameters can be calculated.

In certain situations, it is not reasonable to assume that the first density measurement includes the actual fluid density. Thus, according to an embodiment of the present invention, if the difference between the first density measurement and the actual density exceeds a threshold, two equations can be used to solve the fluid parameters. In accordance with an embodiment of the invention, the fluid parameters include actual fluid density. In accordance with another embodiment of the invention, the fluid parameter includes the speed of sound. In accordance with another embodiment of the invention, the fluid parameter includes the actual mass flow rate. It should be understood that the term “actual” mass flow refers to the mass flow obtained without sonic effects.

Thus, when the first density measurement is not believed to be the actual density, or in situations where the actual density is unknown, equations (6) and (7) can be used in combination. This is determined, for example, if the difference between the first density measurement and the predicted density measurement exceeds a threshold difference. This is true if the vibrometer is a high frequency meter and the sound velocity effect in the density reading state produces an excessive error even at the first frequency.
Therefore, it should be understood that according to other embodiments of the present invention, the calculated sound speed can be used to supplement the sound speed effect of a high frequency meter. For example, if the speed of sound is calculated for a given fluid at a given temperature using equation (5), the calculated sound speed is used in a high frequency meter, for example, the speed of sound using equations (1) and (2). Compensates for density or mass flow error due to effectiveness. However, to run on a high frequency meter, the actual fluid density must be known or both equations (6) and (7) need to be used. This presents two equations for two unknowns (fluid sound velocity and actual density measurement). Therefore, the sound velocity effect in the high frequency meter is compensated using the method according to the invention. The present invention is not limited to equations (6) and (7), and those skilled in the art can be used to calculate other fluid parameters using the first density measurement and at least the second density measurement. It should be understood that other similar equations can be readily recognized.

The calculated sound speed is used for various purposes. In accordance with one embodiment of the present invention, the calculated sound speed is used, for example, with equations (1) and (2) to calculate errors in future density and mass flow measurements. This is particularly useful in embodiments where the flow meter operates at a drive frequency that is high enough to cause errors in density and mass flow measurements due to the speed of sound effect.
The present invention has been described for a vibratory flow meter. Although the above description is primarily directed to Coriolis flow meters, the present invention may be used with other vibrometers that do not include Coriolis flow meter doses.
For example, the vibration meter includes a vibration type density meter. However, the mass and / or amount of flow rate may be desired. Thus, a Coriolis mass flow meter is implemented, but the mass flow capability is only used in that case. By calculating the sound velocity of the fluid, the present invention can calculate the mass flow rate as well. This is particularly true for compressible fluids such as gases.

ここで、
κ＝ガスの比熱比
Ｒは個々の成分のガス定数
Ｔは温度である。
Ｐ＝ρＲＴ （９）
ここでＰ＝圧力
ρ＝実際の流体密度である。 It should be understood that the present invention can be used for a number of purposes once the sound velocity of the fluid has been determined. For example, two variables that are often difficult to determine in a gas are the specific heat ratio κ of the gas and the gas constant R of the individual components. Two equations for often useful gases are the ideal gas sound velocity and the ideal gas equation.

here,
κ = the specific heat ratio R of the gas, the gas constant T of each component is the temperature.
P = ρRT (9)
Where P = pressure ρ = actual fluid density.

Advantageously, in many vibratory flow meters, temperature is a known variable. Thus, once the speed of sound is determined, the remaining variables can be easily calculated. These two equations are often used separately or once combined with a known speed of sound to determine any number of characteristics of the system, such as mixed molecular weight, compressor efficiency, measurement correction, etc. Specific examples should in no way limit the scope of the invention, but are presented only as an aid in understanding the usefulness of the invention and provide examples of how the calculated speed of sound can be used.
One particular advantage of the above method is that the speed of sound of the fluid in the vibrometer can be monitored for changes. A change in the sound speed of the fluid can indicate a number of conditions. In accordance with an embodiment of the present invention, the calculated sound speed for a fluid can be compared to a previously calculated sound speed. The comparison is used, for example, as a diagnostic to determine changes in the fluid composition. In other examples, the comparison can be used, for example, to determine changes in the fluid phase.

In Coriolis flow meter applications, changes in the fluid phase, such as gases entrained in the fluid, can be determined based on changes in drive gain. However, in order for the gain to be affected, the amount of entrained gas needs to exceed a certain threshold amount. The particular threshold depends on the condition and the fluid being monitored. Applicants have determined that even lower levels of entrained gas can be detected by monitoring changes in the sound velocity of the fluid.
In general, the speed of sound of a fluid is greater than the speed of sound of a gas of the same composition. However, the sound speed of the mixed phase is generally lower than any pure phase. For many compositions, when the fluid is composed of one phase and includes a small amount of mixed second phase, for example, a liquid with a small amount of mixed gas, or a liquid or gas mixed with a solid Or when the gas is mixed with liquid soot. One of the main reasons is that the compressibility changes significantly while the density of the mixture remains relatively constant. Thus, the sound speed of the fluid is determined according to one of the methods outlined in this application and compared to the predicted sound speed. If the difference between the calculated sound speed and the predicted sound speed is greater than a threshold, the meter electronics 20 or user / operator determines the error. Errors include, for example, determining that the fluid composition and / or fluid phase has changed. The predicted sound speed is determined based on previously calculated sound speed, or is obtained from a look-up table, values in memory, user / worker input, and the like.

ここで、
ρ＝流れ導管内の密度
ρ_０＝淀み点の密度
κ＝ガスの比熱比(上記の式(８)又は(９)から計算された)
Ｍａ＝マッハ数
従って、式(１０)はマッハ数を計算するのに用いられて、以下のように規定される。
Ｍａ＝Ｖ/ｃ （１１）
ここで、Ｖは流体速度である。従って、音速が既に既知であるから、流れ導管領域が式(
１１)及び(１２)に基づいて既知であれば、体積流量

は計算され得る。

ここで、Ａは流れ導管領域である。密度が既知であるから、質量流量は当該技術分野で一般に知られているように計算される。従って、本発明によって、流速の質量及び/又は
量は、計算された流体の音速に基づいて、振動型密度計を用いて計算され得る。 Although the above comparison compares the initially calculated sound speed with at least the second sound speed, it should be understood that a comparison is made between the calculated sound speed and the predicted sound speed for the fluid. is there. Therefore, only one calculation needs to be done to perform the above determination.
Once the speed of sound is calculated using equation (10), the mass or amount of flow velocity is calculated, which gives the density ratio between the density in the flow conduits 103A and 103B and the density of the stagnation point.

here,
ρ = density in the flow conduit ρ ₀ = stagnation point density κ = specific heat ratio of gas (calculated from the above equation (8) or (9))
Ma = Mach number Therefore, equation (10) is used to calculate the Mach number and is defined as follows.
Ma = V / c (11)
Where V is the fluid velocity. Therefore, since the speed of sound is already known, the flow conduit region is
11) and volume flow rate if known under (12)

Can be calculated.

Where A is the flow conduit region. Since the density is known, the mass flow rate is calculated as is generally known in the art. Thus, according to the present invention, the mass and / or quantity of the flow velocity can be calculated using a vibratory densimeter based on the calculated sound velocity of the fluid.

As noted above, the present invention requires generating first and at least second density measurements. The first and at least second density measurements may be based on the first and at least second frequency responses. The following describes how a frequency response is generated according to an embodiment of the present invention.
FIG. 3 illustrates a circuit 300 that generates a first frequency and at least a second frequency in accordance with an embodiment of the present invention. This embodiment is used with one vibratory flow meter, and therefore the circuit 300 is connected to one pick-off 105, 105 ′ of the vibratory flow meter 5. Circuit 300 includes a portion of meter electronics 20. Alternatively, the circuit 300 is a processing system 707 (FIG. 7).
And the accompanying description). Circuit 300 includes filters 302A and 302B.
, Hilbert transforms block units 304A and 304B, and analysis block units 306A and 306B.

Filter 302A receives a first frequency component (i.e., from pickoff sensors 105, 105 ′).
In some embodiments, the “low mode”) is filtered, while the filter 30
2B filters at least a second frequency component (ie, “high frequency mode” in some embodiments). Filters 302A and 302B thus form two separate processing branches. If more than one vibration frequency is used, more than one processing branch can be configured if desired.
In one embodiment, the filtering includes bandpass filtering centered around the predicted fundamental frequency of the flow meter. Filtering includes filtering to remove noise and unwanted signals. In addition, other adjustment operations such as amplification, buffering, etc. can be performed. If the sensor signal includes an analog signal, this block further includes any method of sampling, digital processing, and decisions performed to generate the digital sensor signal.

In some embodiments, mode filters 302A and 302B include digital finite impulse response (FIR) polyphase decimation filters. However, it should be understood that the mode filter need not constitute an FIR filter, and therefore the particular filter used should not limit the scope of the present invention.
In accordance with one embodiment of the present invention, the filter may be executed in a processing routine or processing system 707 of the processing device or meter electronics 20. These filters provide an optimal way of filtering and decimating the pickoff sensor signal, where the filtering and decimation are performed at the same time and at the same decimation rate. Alternatively, filters 302A and 302B include a finite impulse response (FIR) filter, or other suitable digital filter or filtering. However, it should be understood that other filtering processes and / or embodiments of filtering are contemplated and are within the description and claims.

The Hilbert transform phase 304A shifts the first frequency component by about 90 degrees, and the Hilbert transform phase 304B shifts at least the second frequency component by about 90 degrees. The phase shift operation generates I and Q components (that is, in-phase and quadrature components) of each frequency component. However, it should be understood that a 90 degree phase shift may be performed with any method of phase shifting mechanism or operation.
The I and Q components are received and processed by the analysis block units 306A and 306B. The process generates a first frequency f _A and at least a second frequency f _B. The first frequency f _A and at least the second frequency f _B can be used to generate a first density and at least a second density.
The frequency according to an embodiment of the invention is advantageously calculated from the 90 degree phase shift. The frequency in one embodiment uses a 90 degree phase shift and a corresponding sensor signal from which the 90 degree phase shift is derived (ie, from the I and Q components).
The derived frequency is obtained without the need for any independent frequency reference signal. The frequency is derived from one 90 degree phase shift that is very fast to operate. The resulting frequency has a high degree of accuracy.

FIG. 4 shows details of the Hilbert transform block sections 304A and 304B according to the present invention. In the illustrated embodiment, each Hilbert transform block unit 304 A and 304 B includes a delay block 411 in parallel with the filter block 412. Accordingly, the delay block 411 selects digital signal samples that are delayed in time from the digital signal samples filtered in parallel by the filter block 412. Filter block 412 performs a 90 degree phase shift on the input digital signal samples.
The Hilbert transform block units 304A and 304B generate a 90 degree phase shifted version of the pickoff signal, that is, generate a quadrature (Q) component of the original in-phase (I) signal. Accordingly, the outputs of the Hilbert transform block units 304A and 304B add the original in-phase (I) signal component to the first and at least second vibration responses, and a new orthogonality to the first and at least second vibration responses. Phase (Q) components POQ and POQ are added.

ヒルベルト変換を用いると、出力は以下となる。

元の項をヒルベルト変換の出力と組み合わせれば、以下を算出する。

図５は、本発明の実施例に従った分析ブロック部３０６Ａ又は３０６Ｂのブロック図である。分析ブロック部３０６Ａ又は３０６Ｂは１つのピックオフ(ＰＯ)信号から信号を受信する。示された実施例内の分析ブロック部３０６Ａ又は３０６Ｂは、結合ブロック５０１、複合共役(conjugate)ブロック５０２、サンプリングブロック５０３、複合乗算ブロ
ック５０４、位相角ブロック５０６、定数ブロック５０７、及び除算ブロック５０８を含む。 Inputs to the Hilbert transform block units 304A and 304B are expressed as follows.

Using the Hilbert transform, the output is

Combining the original term with the output of the Hilbert transform yields:

FIG. 5 is a block diagram of the analysis block unit 306A or 306B according to an embodiment of the present invention. The analysis block unit 306A or 306B receives a signal from one pickoff (PO) signal. The analysis block unit 306A or 306B in the illustrated embodiment includes a combining block 501, a composite conjugate block 502, a sampling block 503, a composite multiplication block 504, a phase angle block 506, a constant block 507, and a division block 508. Including.

２つの連続したサンプル間の角度は従って、以下となる。

これは振動応答の角振動数である。Ｈｚに変換すると、

となる。ここで「Ｆｓ」はヒルベルト変換ブロック部３０４Ａ及び３０４Ｂの速度である。 The coupling block 501 receives and passes the in-phase (I) and quadrature (Q) components of a particular vibration response. Composite conjugate block 502 performs composite conjugate on the vibration response to form a negative imaginary signal. The delay block 503 introduces a sampling delay into the analysis block unit 306A or 306B and thus selects a digital signal sample that is older in time. This old digital signal sample is multiplied with the current digital signal in composite multiplication block 504. The composite multiplication block 504 multiplies the PO signal and the PO conjugate signal and executes the following equation (20). Filter block 505 implements a digital filter such as the FIR filter previously described. The filter block 505 comprises a polyphase decimation filter used to remove high harmonics from the in-phase (I) and quadrature (Q) components of the sensor signal as well as remove the signal. The filter coefficients are selected to remove the input signal, such as to remove every 10 factors. The phase angle block 506 determines the phase angle from the in-phase (I) and quadrature (Q) components of the PO signal. The constant block 507 provides a factor that includes the sample rate F _S divided by 2π, as shown in equation (18). The division block 508 executes the division operation of Expression (18).
The analysis block unit 306A or 306B executes the following expression.

The angle between two consecutive samples is therefore:

This is the angular frequency of the vibration response. When converted to Hz,

It becomes. Here, “Fs” is the speed of the Hilbert transform block units 304A and 304B.

FIG. 6 illustrates a circuit 300 that generates a first frequency and at least a second frequency in accordance with one embodiment of the present invention. Elements common to the other embodiments share the same reference numerals. This embodiment further differs from the previous embodiment 300 by including a smoothing filter 609.
This embodiment similarly receives a vibration response from one pickoff sensor 105, 105 ′. However, one vibratory flow meter of this embodiment is vibrated at only one frequency, and noise in the flow meter produces a second vibration response as previously described. Thus, the circuit 300 makes good use of noise in the flow system. Since a small amount of noise activates the sensor mode, the self-induction type high vibration response mode can be detected without a drive signal. This means that only one drive signal is required.
Since higher mode signals (not enhanced by drive) are of smaller amplitude, the method requires further filtering. Since the approximate frequency range of this higher mode vibration response is known, smaller amplitudes are not a significant problem. Furthermore, another concern is that the density measurement is noisy as well because of the small amplitude. As long as a short response time is acceptable, this problem is eliminated by averaging many samples after the frequency measurement is made. To achieve this goal, the smoothing filter 609 averages at least the second frequency and improves frequency removal, thereby reducing noise and errors.

  FIG. 7 shows a vibratory flow meter 700 according to another embodiment of the present invention. The vibration type flow meter 700 includes a first flow meter 5A and at least a second flow meter 5B. The flow meters 5A and 5B are connected in a conduit 71. Both flow meters 5A and 5B measure the flow material flowing in the conduit 71. The processing system 707 is coupled to the first flow meter 5A and at least the second flow meter 5B. The processing system 707 receives a first vibration response from the first flow meter 5A and receives at least a second vibration response from at least the second flow meter 5B. The processing system 707 can determine the first density, at least the second density, and the speed of sound of the flow material as previously described and described below with respect to FIG.

FIG. 8 is a flowchart 800 of a method for determining fluid parameters of a fluid according to one embodiment of the present invention. In step 801, the first vibratory flow meter and at least the second vibratory flow meter are vibrated. The first vibration type flow meter is vibrated at a first frequency to generate a first vibration response. At least a second vibratory flow meter is oscillated at least at a second frequency to generate at least a second vibration response.
In accordance with embodiments of the present invention, two or more flow meters are used. It should be understood that more than one vibratory flow meter can be included and more than one vibratory response can be received. A number of vibration responses are used to further improve the fluid parameter calculation.

In step 802, a first vibration response and at least a second vibration response are received from the first vibration flow meter and at least a second vibration flow meter. At least the second vibration response includes a different frequency than the first vibration response, as previously described.
In step 803, a first fluid characteristic is generated as previously described.
In step 804, at least a second fluid characteristic is generated as previously described.
In step 805, fluid parameters of the flow fluid are calculated based on the first fluid characteristic and at least the second fluid characteristic, as previously described.
The invention described above allows the user / operator of the vibrometer to calculate various fluid parameters. The calculation can be performed based on the vibration response. The vibration response may include at least a first frequency component and at least a second frequency component. The first frequency component and at least the second frequency component are the result of flow meter vibration at a number of frequencies. Alternatively, the first frequency component and at least the second frequency component are the result of flow meter vibration at one frequency. Thus, the present invention does not require the use of a separate acoustic meter to measure the speed of sound, as was required in the prior art.
Further, in some embodiments, the present invention can calculate the speed of sound using only one flow meter.

The calculated sound speed is used in a number of different ways as described above. It should be understood that the above examples are merely examples to highlight the usefulness of the present invention and should not limit the scope of the invention. Rather, the applicability of the present invention is even greater than the limited embodiment described above.
The detailed description of the above examples is not an exhaustive description of all of the examples considered by the inventors as being within the scope of the present invention. Indeed, those skilled in the art will recognize that certain elements of the embodiments described above may be variously combined or removed to produce further embodiments, which are within the scope of the present invention. And will be understood to be included within the disclosure. It will be apparent to those skilled in the art that the embodiments described above may be combined in whole or in part to produce additional embodiments within the scope and disclosure of the present invention.
Thus, although specific embodiments of the invention and examples of the invention have been disclosed herein for purposes of illustration, various equivalent modifications may be made to the invention, as will be recognized by those skilled in the art. It is possible within the range. The disclosure provided herein applies to other vibratory meters and is not limited to the embodiments described above and shown in the accompanying drawings. Accordingly, the scope of the invention should be determined from the following claims.

Claims (45)

A method for calculating the speed of sound of a fluid flowing through at least a first vibratory flow meter comprising:
Vibrating the flow meter at one or more frequencies;
Receiving a vibration response;
Generating a first fluid characteristic of the fluid;
Generating at least a second fluid property of the fluid based on the vibration response;
Determining the predicted fluid properties ;
Comparing the difference between the first fluid property and the predicted fluid property to a threshold value to determine if the first fluid property is an actual fluid property ;
Determining a method of calculating sound speed based on whether the first fluid property is an actual fluid property ;
Calculating the speed of sound based on the first fluid characteristic and at least the second fluid characteristic using the determined method ;
Having a method. The method of claim 1, further comprising calculating a density error based on the calculated sound speed. The method of claim 2, further comprising correcting the density based on the calculated density error. The method of claim 1, further comprising calculating a mass flow error based on the calculated sound velocity. 5. The method of claim 4, further comprising correcting the mass flow based on the calculated mass flow error. The method of claim 1, wherein the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement. The method of claim 1, wherein the first fluid characteristic and the at least second fluid characteristic include a first mass flow rate and at least a second mass flow rate. The process of vibrating the vibratory flow meter
Vibrating the vibratory flow meter at a first frequency;
The method according to claim 1, further comprising vibrating the vibratory flow meter at at least a second frequency that is different from the first frequency. The method of claim 1, further comprising separating the vibration response into a first frequency component of the vibration response and at least a second frequency component of the vibration response. The method of claim 1, wherein the first fluid characteristic is based on a first frequency component of the vibration response, and the at least second fluid characteristic is based on at least a second frequency component of the vibration response. The process of vibrating the vibratory flow meter
Vibrating the vibratory flow meter at a first frequency;
Separating the vibration response into a first frequency component and at least a second frequency component;
The method of claim 1, wherein the first frequency component and at least the second frequency component are generated by vibration at the first frequency. Furthermore,
Vibrating at least the second vibratory flow meter;
Generating a first fluid characteristic from a first vibratory flow meter;
Generating at least a second fluid characteristic from at least a second vibratory flow meter. Vibrating the first vibrometer and at least the second vibrometer,
Vibrating the first vibrometer at a first frequency;
The method of claim 12, comprising oscillating at least a second flow meter at at least a second frequency separate from the first frequency.   The first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, wherein the first density measurement is generated from a known fluid density. Method. The first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement;
The method of claim 1, further comprising: determining that the first density measurement includes an actual fluid density if the difference between the first density measurement and the predicted density measurement is less than a threshold value. Method. The first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow;
2. The method of claim 1, further comprising: determining that the first mass flow rate includes an actual mass flow rate if the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold value. The first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement;
The method of claim 1, comprising calculating the actual fluid density and the sound velocity of the fluid if the difference between the first density measurement and the predicted density measurement exceeds a threshold. The first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow;
The method of claim 1, comprising calculating the actual mass flow rate and the sound velocity of the fluid if the difference between the first mass flow rate and the predicted mass flow rate exceeds a threshold value. In a vibratory flow meter comprising a meter assembly (10) comprising a vibration sensor (104, 105, 105 ′) and meter electronics (20) coupled to the vibration sensor,
Meter electronics (20)
Receive vibration response from vibration sensor,
Generating a first fluid property of the fluid;
Generating at least a second fluid property of the fluid based on the vibrational response;
Determine the predicted fluid properties ,
Comparing the difference between the first fluid property and the predicted fluid property to a threshold value to determine if the first fluid property is an actual fluid property ;
Determining how to calculate the speed of sound based on whether the first fluid property is an actual fluid property ;
A vibratory flow meter (5) configured to calculate the speed of sound based on the first fluid characteristic and at least the second fluid characteristic using the determined method .   20. A vibratory flow meter (5) according to claim 19, wherein the first fluid characteristic and at least the second fluid characteristic comprise a first density measurement and at least a second density measurement.   20. A vibratory flow meter (5) according to claim 19, wherein the first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow.   20. The vibratory flow meter (5) according to claim 19, wherein the first fluid characteristic is based on a first frequency component of the vibration response and at least the second fluid characteristic is based on at least a second frequency component of the vibration response. ).   The meter electronics (20) is further configured to vibrate the vibratory flow meter 5 at a first frequency and at least a second frequency, wherein at least the second frequency is different from the first frequency. The vibration type flow meter (5) described in 1.   20. The vibratory flow meter (5) of claim 19, wherein the meter electronics (20) is further configured to separate the vibration response into a first frequency component and at least a second frequency component. The meter electronics (20) is further configured to vibrate the flow meter at a first frequency and separate the vibration response into a first frequency component and at least a second frequency component,
20. The vibratory flow meter (5) according to claim 19, wherein the first frequency component and at least the second frequency component are generated by vibration at the first frequency.   The first fluid characteristic and at least a second fluid characteristic comprise a first density measurement and at least a second density measurement, wherein the first density measurement is generated from a known fluid density. Vibrating flow meter (5). The first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement;
The meter electronics is further configured to determine that the first density measurement comprises an actual density if a difference between the first density measurement and the predicted density is less than a threshold value. The vibration type flow meter (5) according to 19, The first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow;
The meter electronics is further configured to determine that the first mass flow rate comprises an actual mass flow rate if the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold value. The vibratory flow meter (5) according to claim 19.   20. The vibratory flow meter (5) of claim 19, wherein the meter electronics (20) is further configured to calculate a density error based on the calculated sound speed.   30. The vibratory flow meter (5) of claim 29, wherein the meter electronics (20) is further configured to correct the density based on the density error.   20. The vibratory flow meter (5) of claim 19, wherein the meter electronics (20) is further configured to calculate a mass flow error based on the calculated sound velocity.   32. The vibratory flow meter (5) of claim 31, wherein the meter electronics (20) is further configured to correct the mass flow based on a mass flow error. A first flow meter (5A), at least a second flow meter (5B), a first flow meter (5A), and a processing system (707) connected to at least the second flow meter (5B). The vibratory flow meter system (700) for calculating the sound velocity of the flowing fluid is:
Processing system (707)
Receiving a first vibration response from the first flow meter (5A), receiving at least a second vibration response from at least the second flow meter (5B);
Generating a first fluid property of the fluid;
Generating at least a second fluid characteristic of the fluid based on at least the second vibrational response;
Determine the predicted fluid properties ,
Comparing the difference between the first fluid property and the predicted fluid property to a threshold value to determine if the first fluid property is an actual fluid property ;
Determining how to calculate the speed of sound based on whether the first fluid property is an actual fluid property ;
A vibratory flow meter system (700) configured to calculate a sound velocity of the fluid based on the first fluid characteristic and at least the second fluid characteristic using the determined method .   34. The vibratory flow meter system (700) of claim 33, wherein the first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement.   34. The vibratory flow meter system (700) of claim 33, wherein the first fluid characteristic and the at least second fluid characteristic comprise a first mass flow rate and at least a second mass flow rate.   The processing system is further configured to oscillate the first flow meter (5A) at a first frequency and oscillate at least the second flow meter (5B) at least at a second frequency, and at least the second frequency. 34. The vibratory flow meter system (700) of claim 33, wherein is different from the first frequency.   34. The first fluid characteristic and the at least second fluid characteristic include a first density measurement and at least a second density measurement, wherein the first density measurement is generated from a known fluid density. Vibration type flow meter system (700). The first fluid characteristic and the at least second fluid characteristic include a first density measurement and at least a second density measurement, and the processing system (701) further includes:
34. The apparatus of claim 33, wherein the first density measurement is configured to determine that it includes an actual fluid density if a difference between the first density measurement and the predicted density measurement is less than a threshold value. Vibration type flow meter system (700). The first fluid characteristic and the at least second fluid characteristic comprise a first density measurement and at least a second density measurement, and the processing system (701) further comprises:
34. The vibratory flow meter system of claim 33, configured to calculate an actual fluid density and a fluid sound velocity if a difference between the first density measurement and the predicted density measurement exceeds a threshold value. (700). The first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow, and the processing system (701) further includes
34. The device of claim 33, configured to determine that the first mass flow rate comprises an actual mass flow rate if the difference between the first mass flow rate and the predicted mass flow rate is less than a threshold value. Vibration type flow meter system (700). The first fluid characteristic and at least the second fluid characteristic comprise a first mass flow and at least a second mass flow, and the processing system (701) further includes
34. The vibration type of claim 33, configured to calculate the actual mass flow rate and the sound velocity of the fluid if the difference between the first mass flow rate and the predicted mass flow rate exceeds a threshold value. Flow meter system (700).   The vibratory flow meter system (700) of claim 33, wherein the processing system (701) is further configured to calculate a density error based on the calculated sound velocity.   43. The vibratory flow meter system (700) of claim 42, wherein the processing system is further configured to correct the density based on the calculated density error.   34. The vibratory flow meter system (700) of claim 33, wherein the processing system (701) is further configured to calculate a mass flow error based on the calculated sound velocity.   45. The vibratory flow meter system (700) of claim 44, wherein the processing system (701) is further configured to correct the mass flow rate based on the calculated mass flow error.

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