Apparatus and related method for applying temperature flow coefficient in vibrating flow meter

Abstract

A method for calibrating a flow meter is provided, the method comprising determining a relationship between tube period ratios and flow tube temperature compensation (FTC) values ​​for a plurality of flow meters. The tube period of the flow meter under test is measured. A stiffness-dependent FTC is calculated using the determined relationship between the tube period ratios and FTC values ​​for the plurality of flow meters and the measured tube period of the flow meter under test. The stiffness-dependent FTC is applied to an operating routine (314) of the flow meter under test.

Description

Technical Field

[0001] The present invention relates to flow meters, and more particularly to methods and apparatus for determining a temperature flow coefficient and applying the temperature flow coefficient to a vibrating flow meter. Background Art

[0002] Vibrating sensors, such as vibrating densitometers and Coriolis flowmeters, are generally known and are used to measure mass flow and other information about material flowing through a conduit within the flowmeter. Exemplary Coriolis flowmeters are disclosed in U.S. Patents 4,109,524, 4,491,025, and Re. 31,450, all to J.E. Smith et al. These flowmeters have one or more conduits in straight or curved configurations. Each conduit configuration in a Coriolis mass flowmeter has a set of natural vibration modes, which can be simple bending, torsional, or coupled, for example. Each conduit can be driven to oscillate in a preferred mode.

[0003] Material flows into the flow meter from a connecting pipe on the inlet side of the flow meter, is directed through the conduit, and exits the flow meter through the outlet side of the flow meter.The natural vibration modes of the vibrating system are defined in part by the combined mass of the conduit and the material flowing within the conduit.

[0004] When there is no flow through the flowmeter, the driving force applied to the conduit causes all points along the conduit to oscillate with the same phase or a small "zero offset," which is the time delay measured at zero flow. When material begins to flow through the flowmeter, the Coriolis force causes each point along the conduit to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized drive location, while the phase at the outlet channel leads the phase at the centralized drive location. Detectors on the conduit produce sinusoidal signals representing the motion of the conduit. The signals output from the detectors are processed to determine the time delay between the detectors. The time delay between two or more detectors is proportional to the mass flow rate of the material flowing through the conduit.

[0005] Meter electronics connected to the driver generate a drive signal for operating the driver and determine the mass flow rate and other properties of the material based on the signal received from the detector. The driver can include one of many well-known devices; however, a magnet and an opposing drive coil have been used with great success in the flow meter industry. Alternating current is delivered to the drive coil to cause the conduit to vibrate at the desired flow tube amplitude and frequency. It is also known in the art to provide the detector as a magnet and coil arrangement that is very similar to the driver arrangement. However, when the driver receives a current that causes motion, the detector can use the motion provided by the driver to induce a voltage. The magnitude of the time delay measured by the detector is very small, typically measured in nanoseconds. Therefore, the transducer output must be very accurate.

[0006] Typically, a Coriolis flowmeter can be initially calibrated and a flow calibration factor and a zero offset can be generated. In use, the flow calibration factor (FCF) can be multiplied by the time delay (ΔT) measured by the detector minus the zero offset (ΔT0) to generate a mass flow rate. Such a mass flow calibration can be represented by two calibration constants, which are equivalent to the slope (FCF) and intercept (zero offset) of a straight line. An example of a mass flow rate equation using the flow calibration factor (FCF) and the zero offset (ΔT0) is described by equation (1):

[0007]

[0008] in:

[0009]

[0010] FCF = Flow Calibration Factor

[0011] ΔT 测量 = measured time delay

[0012] ΔT0 = Initial zero offset

[0013] In most cases, flow meters are initially calibrated by the manufacturer and are assumed to provide accurate measurements without the need for subsequent calibration. While the initially determined zero offset may be sufficient to correct measurements in limited circumstances, many operating conditions can affect the zero offset. These include, but are not limited to, temperature, pressure, fluid density, and sensor installation conditions.

[0014] The problem is that the material properties, cross-sectional properties, and stiffness of the flow tubes can change during Coriolis flowmeter operation. For example, changes in the stiffness of the flow tubes can be caused by temperature fluctuations. While all flow meters are sensitive to thermal variations, straight tube meters are inherently more sensitive due to the rigid structural constraints of the straight tubes. This sensitivity can vary from sensor to sensor due to manufacturing variations. These variations vary from meter to meter, and the result is that the tube stiffness varies from meter to meter, which directly affects the temperature correction term and, therefore, requires each meter to have a unique correction term applied to it. Determining a unique correction factor is a time-consuming and expensive process.

[0015] Therefore, there is a need in the art for an apparatus and method for determining and applying a temperature flow coefficient in a faster and more efficient manner.The present invention overcomes the above difficulties, other problems, and achieves an advancement in the art. Summary of the Invention

[0016] According to an embodiment, a method for calibrating a flow meter under test is provided. The method includes determining a relationship between tube period ratios and flow tube temperature compensation (FTC) values ​​for a plurality of flow meters. The tube period of the flow meter under test is measured. A stiffness-dependent FTC is calculated using the determined relationship between the tube period ratios and FTC values ​​for the plurality of flow meters and the measured tube period of the flow meter under test. The stiffness-dependent FTC is applied to an operating routine of the flow meter under test.

[0017] According to an embodiment, a flow meter is provided. The flow meter includes meter electronics, which include a processing system and a storage system. A plurality of detectors are attached to a flow meter conduit in communication with the meter electronics. A driver is attached to the flow meter conduit and in communication with the meter electronics. The meter electronics is configured to apply stiffness-dependent FTC to an operating routine, wherein the stiffness-dependent FTC is calculated using a predetermined relationship between tube period ratios and FTC values ​​for a plurality of flow meters and a measured tube period of the flow meter. The operating routine of the meter electronics is configured to apply the stiffness-dependent FTC to the operating routine.

[0018] All aspects

[0019] According to one aspect, a method for calibrating a flow meter under test is provided, the method comprising determining a relationship between tube period ratios and flow tube temperature compensation (FTC) values ​​for a plurality of flow meters. The tube period of the flow meter under test is measured. A stiffness-dependent FTC is calculated using the determined relationship between the tube period ratios and FTC values ​​for the plurality of flow meters and the measured tube period of the flow meter under test. The stiffness-dependent FTC is applied to an operating routine of the flow meter under test.

[0020] Preferably, the tube period ratio comprises a K value, ie, K1 divided by K2, wherein K1 comprises the tube period of the flow meter sensor filled with air, and K2 comprises the tube period of the flow meter sensor filled with water.

[0021] Preferably, the relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of flow meters comprises a linear relationship between the tube cycle ratio and the FTC value of the plurality of flow meters having the same size and model.

[0022] Preferably, measuring the tube period of the measured flow meter includes measuring tube periods K1 and K2, wherein K1 includes the tube period of the measured flow meter sensor filled with air, and K2 includes the tube period of the measured flow meter sensor filled with water.

[0023] Preferably, calculating the stiffness-related FTC includes multiplying a slope value derived from the relationship between tube period ratios and flow tube temperature compensation values ​​for a plurality of flow meters by the ratio K1 :K2 of the flow meter under test.

[0024] Preferably, a y-intercept derived from the relationship between tube cycle ratio and flow tube temperature compensation values ​​for a plurality of flow meters is subtracted from the product of the slope value and the K1 :K2 ratio of the flow meter being measured.

[0025] Preferably, the step of applying stiffness-dependent FTC to the operating routine comprises applying stiffness-dependent FTC to the mass flow routine.

[0026] Preferably, the flow meter under test includes a straight flow tube.

[0027] According to one aspect, a flow meter is provided that includes meter electronics, the meter electronics including a processing system and a storage system. A plurality of detectors are attached to a flow meter conduit that communicates with the meter electronics. A driver is attached to the flow meter conduit and communicates with the meter electronics. The meter electronics is configured to apply a stiffness-dependent FTC to an operating routine, wherein the stiffness-dependent FTC is calculated using a predetermined relationship between tube period ratios and FTC values ​​for a plurality of flow meters and a measured tube period of the flow meter. The operating routine of the meter electronics is configured to apply the stiffness-dependent FTC to the operating routine.

[0028] Preferably, the stiffness-related FTC is calculated using the measured tube period of the flow meter.

[0029] Preferably, the conduit comprises a straight flow tube.

[0030] Preferably, the meter electronics are configured to measure a fluid flow rate of a process fluid in the flow meter and to determine at least one fluid characteristic of the process fluid.

[0031] Preferably, the tube period ratio comprises a K value, K1 divided by K2, wherein K1 comprises the tube period of the flow meter sensor filled with air, and K2 comprises the tube period of the flow meter sensor filled with water.

[0032] Preferably, the predetermined relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of flow meters comprises a linear relationship between the tube cycle ratio and the FTC value for the plurality of flow meters having the same size and model.

[0033] Preferably, measuring the tube period of the flow meter includes measuring tube periods, namely K1 and K2, wherein K1 includes the tube period of the flow meter filled with air, and K2 includes the tube period of the flow meter filled with water.

[0034] Preferably, calculating the stiffness-related FTC includes multiplying a slope value derived from the relationship between tube period ratio and flow tube temperature compensation values ​​for the plurality of flow meters by a K1 :K2 ratio for the flow meter.

[0035] Preferably, a y-intercept derived from the relationship between tube period ratio and flow tube temperature compensation values ​​for a plurality of flow meters is subtracted from the product of the slope value and the K1 :K2 ratio of the flow meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 shows a vibrating sensor assembly according to an embodiment of the invention;

[0037] Figure 2 shows meter electronics according to an embodiment of the invention;

[0038] Figure 3 illustrates the temperature induced errors in a flow meter without the implementation of a correction factor;

[0039] Figure 4 illustrates temperature-induced errors in a flow meter with the implementation of custom meter-specific correction factors;

[0040] Figures 5A to 5C illustrates the temperature-induced errors in three flow meters with the global correction factor implemented;

[0041] Figure 6 An example of the relationship between the tube cycle ratio and the FTC value is illustrated;

[0042] 7A to 7C illustrates temperature induced errors in three flow meters with implementation of cycle ratio derived FTC correction factors; and

[0043] Figure 8 A method according to an embodiment is illustrated. DETAILED DESCRIPTION

[0044] Figures 1 to 8 The following description describes specific examples to teach those skilled in the art how to make and use the best mode of the present invention. For the purpose of teaching the principles of the invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations of these examples fall within the scope of the present invention and will understand that the features described below can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the specific examples described below, but is limited only by the claims and their equivalents.

[0045] Figure 1 An example of a flow meter 5 in the form of a Coriolis flow meter is illustrated, which includes a sensor assembly 10 and one or more meter electronics 20. The meter electronics 20 are connected to the sensor assembly 10 to measure fluid properties of the flowing material, such as density, mass flow rate, volume flow rate, total mass flow, temperature, and other information.

[0046] Sensor assembly 10 includes a pair of flanges 101 and 101', and a conduit 103. In this example, flanges 101 and 101' are attached to spacers 102 and 102'. Spacers 102 and 102' are attached to opposite ends of conduit 103. In this example, spacers 102 and 102' maintain spacing between flanges 101 and 101' and conduit 103 to prevent unwanted vibrations in conduit 103. Conduit 103 extends outward from flanges 101 and 101'. When sensor assembly 10 is inserted into a piping system (not shown) carrying flowing material, the material enters sensor assembly 10 through flange 101 and into conduit 103, where it exits sensor assembly 10 through flange 101'. Flanges 101 and 101' may have mounting holes 106 and 106' configured to receive fasteners for mounting to the piping system. In an embodiment, the catheter 103 may be attached to the housing 114 via struts 115, 115'. In another embodiment, the struts 115, 115' are independent of the catheter 103 and may be used to support structures associated with the sensor assembly 10.

[0047] Sensor assembly 10 includes a driver 104. Driver 104 is attached to conduit 103 at a location where it can cause conduit 103 to vibrate in a driven mode. More specifically, driver 104 includes a first driver component (not shown) attached to conduit 103 and a second driver component attached to a structure different from conduit 103. Driver 104 can include one of many well-known arrangements, such as, for example, a magnet mounted to conduit 103 and an opposing coil mounted to a mounting bracket 113. Housing 114 can have end caps 116, 116' attached to housing 114.

[0048] In this example, the drive mode is the first out-of-phase bending mode, and the conduit 103 is selected and appropriately mounted to the flanges 101 and 101' to provide a balanced system with a relatively predictable and / or constant mass distribution, moment of inertia, and elastic modulus about the longitudinal bending axis. In this example, when the drive mode is the first out-of-phase bending mode, the conduit 103 is driven by the driver 104. A drive signal in the form of an alternating current can be provided by one or more meter electronics 20, such as, for example, via path 110, and passed through the driver coil to cause the conduit 103 to oscillate. Those skilled in the art will appreciate that other drive modes may be used within the scope of this embodiment.

[0049] The illustrated sensor assembly 10 includes a pair of detectors 105, 105' attached to a conduit 103. More particularly, a first detector component (not shown) is located on the conduit 103 and a second detector component is located on a structure independent of the conduit 103. In the depicted embodiment, the detectors 105, 105' can be electromagnetic detectors, such as a detector magnet and a detector coil that generate a detector signal representing the velocity and position of the conduit 103. For example, the detectors 105, 105' can supply the detector signal to one or more meter electronics 20 via paths 111, 111'. It will be understood by those of ordinary skill in the art that the movement of the conduit 103 is proportional to certain properties of the flowing material, such as the mass flow rate and density of the material flowing through the conduit 103.

[0050] It should be understood that while the sensor assembly 10 described above includes a single-conduit flowmeter, it is within the scope of this embodiment to implement a multi-conduit flowmeter. Furthermore, while the flow conduit 103 is shown as comprising a straight flow conduit configuration, this embodiment can be implemented with a flowmeter comprising a curved / bent flow conduit configuration. It should also be understood that the detectors 105, 105' can include strain gauges, optical sensors, laser sensors, or any other sensor type known in the art. Therefore, the specific embodiment of the sensor assembly 10 described above is merely an example and should in no way limit the scope of this embodiment.

[0051] exist Figure 1 In the example shown in FIG, one or more meter electronics 20 receive detector signals from detectors 105, 105'. Path 26 provides input and output means that allow the one or more meter electronics 20 to interface with an operator. The one or more meter electronics 20 measure properties of the flowing material, such as, for example, phase difference, frequency, time delay, density, mass flow rate, volume flow rate, total mass flow rate, temperature, meter calibration, and other information. More specifically, the one or more meter electronics 20 receive one or more signals, for example, from detectors 105, 105' and, in one embodiment, one or more signals from one or more temperature sensors 107, such as a resistance temperature device (RTD), and use this information to measure properties of the flowing material.

[0052] It should be understood that while the sensor assembly 10 described above includes a single conduit flow meter, it is also within the scope of the present invention to implement a dual or multi-conduit flow meter. Furthermore, while the flow conduit 103 is shown as comprising a straight conduit, curved flow conduit configurations are also within the scope of the present invention. Therefore, the specific embodiment of the sensor assembly 10 described above is merely an example and should in no way limit the scope of the present invention.

[0053] Figure 2Meter electronics 20 according to an embodiment of the invention is shown. Meter electronics 20 may include an interface 301 and a processing system 303. Processing system 303 may include a storage system 304. Storage system 304 may include internal memory and / or external memory. Meter electronics 20 may generate a drive signal 311 and supply drive signal 311 to driver 104. Additionally, meter electronics 20 may receive sensor signals 310 from detectors 105, 105', such as detector / velocity sensor signals, strain gauge signals, optical signals, or any other signals known in the art. In some embodiments, sensor signals 310 may be received from driver 104. Meter electronics 20 may operate as a density meter or as a mass flow meter, including as a Coriolis flow meter. It should be understood that meter electronics 20 may also operate as some other type of vibrating sensor assembly and that the specific examples provided should not limit the scope of the invention. Meter electronics 20 may process sensor signals 310 to obtain flow characteristics of the material flowing through flow conduits 103A, 103B. For example, in some implementations, the meter electronics 20 may receive a temperature signal 312 from one or more resistance temperature detector (RTD) sensors or other temperature sensors 107 .

[0054] Interface 301 can receive sensor signals 310 from driver 104 or detectors 105, 105' via paths 110, 111, 111'. Interface 301 can perform any necessary or desired signal conditioning, such as any form of formatting, amplification, buffering, etc. Alternatively, some or all of the signal conditioning can be performed in processing system 303. Furthermore, interface 301 can facilitate communication between meter electronics 20 and external devices. Interface 301 can enable any form of electronic, optical, or wireless communication.

[0055] In one embodiment, the interface 301 may include a digitizer 302, wherein the sensor signal includes an analog sensor signal. The digitizer 302 may sample and digitize the analog sensor signal and generate a digital sensor signal. The digitizer 302 may also perform any required decimation, wherein the digital sensor signal is decimated to reduce the amount of signal processing required and reduce processing time.

[0056] The processing system 303 may perform operations of the meter electronics 20 and process flow measurements from the sensor assembly 10. The processing system 303 may execute one or more processing routines, such as a general operating routine 314 and a calibration routine 316, and thereby process inputs to produce one or more flow measurements that are accurate under a wide variety of conditions.

[0057] As an example of an overview of an implementation of the calibration routine 316, the system can be calibrated using a factory zero value under no-flow conditions. The user can additionally and optionally perform a push-button zero at any time. These various zero values ​​are stored in the storage system 304. As part of the operating routine 314, the meter electronics 20 can generate and store values ​​associated with process functions, such as the flow rate of the process material, the density of the process material, and any user-specific settings, such as any post-calibration offsets, for example, but not limited to.

[0058] Meter electronics 20 inputs / measurements, saved values / constants, user settings, saved tables, etc. can be used by calibration routine 316. Calibration routine 316 monitors the condition of flow meter 5 and applies the calibration algorithm deemed most appropriate for the conditions. Conditions can include user input conditions, for example, but not limited to, such conditions. Conditions can also include any combination of temperature, fluid density, flow rate, meter specifications, viscosity, Reynolds number, post-calibration offset, etc. Any number of algorithms can be applied as part of calibration routine 316. Furthermore, in addition to different algorithms, different constants, such as a flow calibration factor (FCF), for example, but not limited to, such constants, can be applied to the selected algorithm based on operating conditions or user preferences.

[0059] Additionally, in the meter electronics 20 according to the invention, the vibration response is also processed to determine a stiffness parameter (K) of the meter assembly 10. Furthermore, the meter electronics 20 can process two or more such vibration responses over time to detect stiffness changes (ΔK) in the meter assembly 10. Stiffness determinations can be made under flow conditions or no-flow conditions. No-flow determinations can provide the benefit of reducing noise levels in the derived vibration response.

[0060] The flow calibration factor (FCF) reflects the material properties and cross-sectional properties of the flow tube. The mass flow rate of the flowing material passing through the flow meter is determined by multiplying the measured time delay (or phase difference / frequency) by the FCF. The FCF can be related to the stiffness characteristics of the meter assembly. If the stiffness characteristics of the meter assembly vary, the FCF will also vary. Changes in flow meter stiffness will therefore affect the accuracy of the flow measurement generated by the flow meter.

[0061] The operating routine may include a mass flow routine, such as equation (1) or equation (2), below:

[0062]

[0063] in:

[0064] τ c =τ m *{1-DT*TT -DTG*(T T -T 平均 )} 1 / 2 (3)

[0065]

[0066] T 平均 = Average value of reference tube and shell temperature

[0067] δt 流动 = time delay during flow

[0068] δt 零 = Time delay during zero flow

[0069] FT = flow tube temperature compensation

[0070] FTG = Flow Temperature Gradient Compensation

[0071] DT = Density tube temperature compensation

[0072] T T =Tube temperature

[0073] FFQ = Tube Cycle Compensation

[0074] K2=High density tube period

[0075] DTG = Density Gradient Temperature Compensation

[0076] τ m = measured tube period

[0077] The operating routine may include a mass flow routine, such as equation (4), below:

[0078]

[0079] in:

[0080]

[0081] C2=C1*K1 2 -D1 (6)

[0082] τ cp =τ fd *{1-DT*T T -DTG*(T T -T 平均 )} 1 / 2 (7)

[0083] τ fd =τ m -F d *δt 2(8)

[0084] ρ = density

[0085] τ m = measured tube period

[0086] T T =Tube temperature

[0087] F d = Fluid density compensation

[0088] DT = Density tube temperature compensation

[0089] τ fd = Tube period for mass flow rate compensation

[0090] τ cp = Tube period for mass flow rate and temperature compensation

[0091] DTG = Density Gradient Temperature Compensation

[0092] DFQ1 / DFQ2 = Density linearization factor

[0093] T 平均 = Average value of reference tube and shell temperature

[0094] δt = time delay

[0095] D1 = density of the low-density fluid

[0096] D2 = density of the high-density fluid

[0097] K1=low density tube period

[0098] K2=High density tube period

[0099] Processing system 303 may include a general-purpose computer, a microprocessor system, a logic circuit, or some other general-purpose or custom processing device. Processing system 303 may be distributed across multiple processing devices. Processing system 303 may include any form of integrated or independent electronic storage medium, such as storage system 304.

[0100] The processing system 303 processes the sensor signal 310 to generate a drive signal, etc. The drive signal is supplied to the driver 104 via the path 110 to cause the associated flow tube, such as Figure 1 The conduit 103 vibrates.

[0101] It should be understood that the meter electronics 20 may include various other components and functions generally known in the art. For the sake of simplicity, these additional features have been omitted from the description and figures. Therefore, the present invention should not be limited to the specific embodiments shown and discussed.

[0102] Go to Figure 3 Flow meter 5 was tested over an operating temperature range starting at a flow tube temperature of approximately 20°C to a flow tube temperature of approximately 40°C. No flow or temperature correction was applied to meter electronics 20. Multiple measurements were taken at 20°C, 30°C, and 40°C, labeled A, B, and C, respectively. It will be apparent that the flow error increases dramatically as the tube temperature increases.

[0103] Figure 4 The diagram shows how this flow error can be easily corrected on a meter-by-meter basis by adjusting FCF, FTC, FTG, and FTQ. This is done on a test bench, and the correction is made only for the meter being tested. The necessary testing and correction calculations required take many hours to implement and are completely impractical for manufacturing because the process is too labor-intensive and cost-prohibitive.

[0104] By way of example, the average global correction factors for FCF, FTC, FTG, and FTQ are applied to Figure 5A 、 Figure 5B and Figure 5C Figure 1 shows three different flow meters. As noted above, straight tube flow meters are particularly sensitive to thermal changes because the straight tube is constrained within a rigid balance bar that limits thermal expansion. As the meter changes temperature, the flow tube is placed in compression (high temperature) or tension (low temperature), thereby changing the stress state, which is in addition to the modulus changes caused by temperature changes and manufacturing variations. Comparing the trend lines (T) in each figure, it will be clear that a global correction factor is not an appropriate solution because manufacturing tolerances lead to unpredictable errors. For example, Figure 5A The flow meter shown has a slightly negative slope error trend, and this error trend is Figure 5B This is more severe in the flow meter shown. Figure 5C For the flow meter shown, the error trend slopes in the opposite direction. This highly variable error pattern is completely unacceptable for a production unit, and it will again be clear that a global correction factor cannot simply be applied to the flow meter because the measurement errors are too large and too unpredictable.

[0105] Typically, the mass flow equation, Equation 1, is corrected for temperature changes by simply multiplying the FCF by the flow tube temperature compensation (FTC) (%T Chg / 100°C). This approach works well for curved tube flowmeters, where the effects of thermal expansion are minimal and the FTC term corrects only for modulus changes. However, for straight tube meters, the FTC term attempts to correct for modulus changes and the stress state established during manufacturing. As explained above, this stress state can vary from meter to meter and make the use of a global FTC inaccurate.

[0106] In an embodiment, several flow meters of the same size / model are used to determine meter-specific FTC values. These FTC values ​​are then correlated to a "stress state" value. In an embodiment, the "stress state" is a ratio of K values. The K values, K1 and K2, are values ​​determined during a standard calibration process and include tube periods of the sensor filled with air (K1) and filled with water (K2). If the K ratio (K1 divided by K2) is compared to the meter-specific FTC values ​​of the "several flow meters of the same size / model" mentioned above (the several flow meters are illustrated as flow meter 1, F1; flow meter 2, F2; and flow meter 3, F3), a linear relationship is determined, as shown in FIG. Figure 6 As shown.

[0107] Using the slope-intercept formula from Figure 7, as an example, the following can be calculated:

[0108]

[0109] By means of Equation 9, the meter-specific FTC value is determined at the standard calibration point using the values ​​collected during calibration, namely, K1 and K2. It should be noted that this slope value is merely an example and in no way limits the embodiments of the present invention, as the slope, y-intercept, and K value will vary depending on the meter being tested and the test conditions. It is also contemplated that other nonlinear relationships, in addition to a sloped line, may be utilized. Furthermore, averaged curves or curves adapted to a specific subject are also contemplated. Furthermore, instead of a formula, a lookup table stored in meter electronics 20 is also contemplated.

[0110] Figure 7A 、 Figure 7B and Figure 7C It is expressed in Figure 5A 、 Figure 5B and Figure 5C The same three different flowmeters are shown in Figure 2. However, in 7A to 7C In the embodiment, the stiffness-dependent coefficient FTC has been applied to each flow meter. It will be clear that the flow error caused by using the stiffness-dependent FTC value is much lower than the flow error caused by using the global / average FTC value.

[0111] It should also be noted that this method can also be used with curved pipes, but the variation between FTC values ​​will be less than that using a straight pipe meter.

[0112] Figure 8FIG8 is a flow chart illustrating an embodiment of a method for calibrating a flow meter. In step 800, FTC is measured in multiple flow meters of the same model type. In step 802, tube periods K1 and K2 of flow meter 5 are determined for the multiple flow meters of the same model type from step 800. As discussed herein, these tube periods are tube periods measured using air and water, respectively, in a flow conduit.

[0113] In step 804, the relationship between the FTC of step 800 and the tube period of step 802 is determined. In an embodiment, the K1:K2 ratio is correlated with the measured FTC value. As noted above, this correlation is represented by a sloping line. It will be appreciated that other nonlinear relationships besides a sloping line may also be utilized. Furthermore, curves suitable for a particular subject matter may also be envisioned.

[0114] As part of the calibration process, the tube periods of the flow meter, K1 and K2, are measured in step 806. These tube periods are for the particular flow meter being measured.

[0115] In step 808, a stiffness-related coefficient FTC is calculated using the measured flow meter tube periods K1 and K2 and the relationship between the previously measured FTC value and the previously measured K1:K2 ratio. In an embodiment, the stiffness-related coefficient FTC is determined based on the measured flow meter tube periods K1 and K2 using an equation having the structure of Equation 9.

[0116] As described above, the present invention provides various methods and apparatus for determining coefficients and applying the coefficient determination to a vibrating flow meter, such as a Coriolis flow meter. Although the various embodiments described above are directed to flow meters, and in particular Coriolis flow meters, it should be understood that the present invention should not be limited to Coriolis flow meters, but rather the methods described herein can be used with other types of flow meters or vibrating sensors that lack some of the measurement capabilities of Coriolis flow meters.

[0117] 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 invention. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments may be variously combined or eliminated to produce additional embodiments, and such additional embodiments fall within the scope and teachings of the present invention. It will also be apparent to those skilled in the art that the above-described embodiments may be combined in whole or in part to produce additional embodiments within the scope and teachings of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

Claims

1. A method for calibrating a Coriolis flowmeter under test, the method comprising: measuring a first tube period of the Coriolis flowmeter under test filled with a low-density fluid flowing through the Coriolis flowmeter under test, and measuring a second tube period of the Coriolis flowmeter under test filled with a high-density fluid flowing through the Coriolis flowmeter under test; calculating a tube period ratio of the Coriolis flowmeter under test by dividing the first tube period by the second tube period; determining a relationship between a tube cycle ratio and a flow tube temperature compensation value for a plurality of flow meters; calculating stiffness-dependent flow tube temperature compensation for the Coriolis flow meter under test by using the determined relationship between the tube period ratios and flow tube temperature compensation values ​​for the plurality of flow meters and the measured tube period ratio of the Coriolis flow meter under test; The stiffness-dependent flow tube temperature compensation is applied to an operating routine (314) of the Coriolis flow meter under test.

2. The method according to claim 1, wherein The tube period ratio includes a K value, ie, K1 divided by K2, where K1 includes the tube period of the flow meter sensor filled with air, and K2 includes the tube period of the flow meter sensor filled with water.

3. The method according to claim 1, wherein The relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of flow meters includes a linear relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of flow meters having the same size and model.

4. The method according to claim 1, wherein Measuring the tube period of the measured Coriolis flowmeter includes measuring tube periods, namely K1 and K2, wherein K1 includes the tube period of the measured flowmeter sensor filled with air, and K2 includes the tube period of the measured flowmeter sensor filled with water.

5. The method according to claim 4, wherein Calculating the stiffness-related flow tube temperature compensation includes multiplying a slope value derived from the relationship between the tube period ratio and the flow tube temperature compensation value for the plurality of flow meters by a K1:K2 ratio of the Coriolis flow meter under test.

6. The method according to claim 5, wherein: A y-intercept derived from the relationship between the tube cycle ratio and flow tube temperature compensation values ​​for the plurality of flow meters is subtracted from the product of the slope value and the K1:K2 ratio of the Coriolis flow meter under test.

7. The method according to claim 1, wherein Applying the stiffness-dependent flow tube temperature compensation to the operating routine includes applying the stiffness-dependent flow tube temperature compensation to a mass flow routine.

8. The method according to claim 1, wherein The Coriolis flowmeter under test includes a straight flow tube.

9. A Coriolis flowmeter (5), comprising: Meter electronics (20), said meter electronics (20) comprising a processing system (303) and a storage system (304); catheter (103); a plurality of detectors (105, 105') attached to the conduit (103) in communication with the meter electronics (20); a driver (104) attached to the conduit (103) in communication with the meter electronics (20); wherein the stiffness-dependent flow tube temperature compensation is calculated by using the determined correlation between the tube period ratio and the flow tube temperature compensation value for a plurality of Coriolis flow meters and the measured tube period ratio of the Coriolis flow meter (5) in the following manner: measuring a first tube period of the Coriolis flowmeter (5) filled with a low-density fluid, and measuring a second tube period of the Coriolis flowmeter (5) filled with a high-density fluid; calculating a tube period ratio of the Coriolis flowmeter (5) by dividing the first tube period by the second tube period; determining a correlation between tube cycle ratio and flow tube temperature compensation values ​​for a plurality of Coriolis flow meters; and The meter electronics (20) is configured to apply stiffness-dependent flow tube temperature compensation of the Coriolis flow meter (5) to an operating routine (314).

10. The Coriolis flow meter according to claim 9, wherein: The stiffness-dependent flow tube temperature compensation is calculated using the measured tube period of the Coriolis flowmeter (5).

11. The Coriolis flow meter according to claim 9, wherein: The conduit (103) comprises a straight flow tube.

12. The Coriolis flow meter according to claim 9, wherein: The meter electronics (20) is configured to measure the fluid flow of a process fluid in the Coriolis flow meter and determine at least one fluid property of the process fluid.

13. The Coriolis flow meter according to claim 9, wherein: The tube period ratio includes a K value, ie, K1 divided by K2, where K1 includes the tube period of the flow meter sensor filled with air, and K2 includes the tube period of the flow meter sensor filled with water.

14. The Coriolis flow meter according to claim 9, wherein: The predetermined relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of Coriolis flow meters includes a linear relationship between the tube cycle ratio and the flow tube temperature compensation value for the plurality of Coriolis flow meters having the same size and model.

15. The Coriolis flow meter according to claim 9, wherein: Measuring the tube period of the Coriolis flowmeter (5) includes measuring tube periods, namely K1 and K2, wherein K1 includes the tube period of the Coriolis flowmeter (5) filled with air, and K2 includes the tube period of the Coriolis flowmeter (5) filled with water.

16. The Coriolis flow meter of claim 15, wherein: Calculating the stiffness-dependent flow tube temperature compensation includes multiplying a slope value derived from a relationship between tube period ratios and flow tube temperature compensation values ​​for a plurality of Coriolis flow meters by a K1:K2 ratio of the Coriolis flow meter (5).

17. The Coriolis flow meter of claim 16, wherein: A y-intercept derived from the relationship between tube period ratio and flow tube temperature compensation values ​​for a plurality of Coriolis flowmeters is subtracted from the product of the slope value and the K1:K2 ratio of the Coriolis flowmeter (5).

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