Detecting measurement bias of a reference zero flow value

Abstract

A vibratory meter (5) configured to detect a measurement bias of a reference zero flow value is provided. The vibratory meter (5) includes a sensor assembly (10) and meter electronics (20) communicatively coupled with the sensor assembly (10). The meter electronics (20) is configured to measure a plurality of zero flow values of the sensor assembly (10) and compare the plurality of zero flow values to a reference zero flow value to determine an indicator of a bias of the reference zero flow value.

Description

Technical Field

[0001] The implementation described below relates to verifying the operation of a vibration meter, and more specifically, to detecting a measurement bias of a reference zero flow value. Background Technology

[0002] Vibration meters, such as Coriolis mass flow meters, liquid densitometers, gas densitometers, fluid viscometers, gas / liquid hydrometers, gas / liquid relative density meters, and gas molecular weight meters, are commonly known and used to measure the properties of fluids. Typically, a vibration meter comprises a sensor assembly and metering electronics. The material within the sensor assembly can be flowing or stationary. Vibration meters can be used to measure the mass flow rate, density, or other properties of the material within the sensor assembly.

[0003] To measure this fluid property of a material, a vibration meter may need to use a reference zero flow value. The reference zero flow value can be equivalent to the zero flow value of the property being measured. The actual non-zero characteristic can be quantified as a scaled or unscaled difference from the reference zero flow value. As can be understood, accurate measurement of the actual non-zero characteristic may depend on an accurate reference zero flow value. An accurate reference zero flow value can be determined through zero calibration. The accuracy of the reference zero flow value can be verified using zero verification. Zero calibration and zero verification can be performed by fluidly isolating the vibration meter such that any measurement can be correctly assumed to reflect a characteristic with a zero flow value (e.g., zero flow rate).

[0004] Figure 1 A system 1 is shown that can perform zero verification and zero calibration of a vibration meter 5. For example... Figure 1 As shown, system 1 includes a meter inlet shut-off valve 2a and a meter outlet shut-off valve 2b. The meter inlet shut-off valve 2a and the meter outlet shut-off valve 2b are configured to prevent fluid flow. Therefore, the flow rate of fluid through the vibrating meter 5 can be zero. A fluid bypass circuit 3 is also shown, which includes a bypass inlet pipe 3a, a bypass shut-off valve 3b, and a bypass outlet pipe 3c. The bypass inlet pipe 3a, the bypass shut-off valve 3b, and the bypass outlet pipe 3c are configured to allow fluid to bypass the vibrating meter 5 when the bypass shut-off valve 3b is open. Upstream of the vibrating meter 5 are a drain valve port 4a and a thermocouple sheath port 4b.

[0005] During zero verification and zero calibration, the meter inlet shut-off valve 2a and the meter outlet shut-off valve 2b are closed to prevent fluid flow through the vibration meter 5. This can be referred to as the zero-flow condition of the vibration meter 5. During zero verification and zero calibration, the vibration meter 5 can measure one or more zero-flow values, which can be values ​​associated with the zero flow rate of the fluid. In a Coriolis meter, when the vibration meter 5 is in the zero-flow condition, the zero-flow value can be the time delay or phase difference between sensor signals.

[0006] Vibration meter 5 can use a reference zero flow value to calculate the flow rate of fluid passing through it. During zero calibration, vibration meter 5 can determine one or more zero flow values ​​that can be used to calculate the reference value. During zero verification, vibration meter 5 can compare one or more zero flow values ​​with a standard to determine whether the reference zero flow value can be used to calculate the fluid flow rate. If the reference zero flow value is not acceptable, zero calibration can be performed.

[0007] A previously determined reference zero flow rate value can be compared with one or more zero flow rate values ​​to determine whether the reference zero flow rate value can be used to calculate the fluid flow rate. Such a comparison can employ a zero-validation criterion. However, a zero-validation criterion may not be suitable for a particular process. Furthermore, various processes may be used at locations where different levels of flow rate measurement accuracy may be required. In addition, the reference zero flow rate value may introduce a measurement bias that may not be acceptable for many or all processes. Therefore, there is a need to detect measurement bias in the reference zero flow rate value. Summary of the Invention

[0008] A metering electronics device is provided, configured to detect a measurement bias of a reference zero flow value. According to one embodiment, the metering electronics device includes an interface communicatively coupled to a sensor assembly containing fluid and a processing system communicatively coupled to the interface. The processing system is configured to measure a plurality of zero flow values ​​of the sensor assembly and compare the plurality of zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value.

[0009] A method is provided for detecting a measurement bias of a reference zero flow value. According to an embodiment, the method includes measuring a plurality of zero flow values ​​of a sensor assembly, comparing the plurality of zero flow values ​​with a reference zero flow value, and determining a bias indicator of the reference zero flow value based on the comparison.

[0010] A vibration meter is provided, configured to detect a measurement bias of a reference zero flow value. According to one embodiment, the vibration meter includes a sensor assembly containing fluid and metering electronics communicatively coupled to the sensor assembly.

[0011] All aspects

[0012] According to one aspect, a metering electronics device configured to detect a measurement bias of a reference zero flow value includes an interface communicatively coupled to a sensor assembly containing fluid and a processing system communicatively coupled to the interface. The processing system is configured to measure multiple zero flow values ​​of the sensor assembly and compare the multiple zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value.

[0013] Preferably, the processing system configured to compare a plurality of zero flow values ​​with a reference zero flow value includes a processing system configured to determine a plurality of differences between the plurality of zero flow values ​​and the reference zero flow value.

[0014] Preferably, the bias indicator referencing the zero flow value includes a sign ratio of multiple differences.

[0015] Preferably, the sign ratio comprises the count of one of the positive and negative values ​​among a plurality of differences divided by the total count of the plurality of differences.

[0016] Preferably, the bias indicator is a central tendency value of multiple differences and a reliability indicator of the central tendency value.

[0017] Preferably, the reliability indicator of the central tendency value is the discrete value of the central tendency value.

[0018] Preferably, the processing system is further configured to compare the bias indicator with a bias indicator reliability threshold.

[0019] According to one aspect, a method for detecting a measurement bias of a reference zero flow value includes measuring a plurality of zero flow values ​​of a sensor assembly, comparing the plurality of zero flow values ​​with a reference zero flow value, and determining a bias indicator of the reference zero flow value based on the comparison.

[0020] Preferably, comparing multiple zero flow values ​​with a reference zero flow value includes determining multiple differences between the multiple zero flow values ​​and the reference zero flow value.

[0021] Preferably, the bias indicator referencing the zero flow value includes a sign ratio of multiple differences.

[0022] Preferably, the sign ratio comprises the count of one of the positive and negative values ​​among a plurality of differences divided by the total count of the plurality of differences.

[0023] Preferably, the bias indicator is a central tendency value of multiple differences and a reliability indicator of the central tendency value.

[0024] Preferably, the reliability indicator of the central tendency value is the discrete value of the central tendency value.

[0025] Preferably, the bias indicator is compared with a bias indicator reliability threshold.

[0026] According to one aspect, a vibration meter configured to detect a measurement bias of a reference zero flow value includes a sensor assembly containing fluid and metering electronics communicatively coupled to the sensor assembly. Attached Figure Description

[0027] In all the accompanying drawings, the same reference numerals denote the same elements. It should be understood that the drawings are not necessarily drawn to scale.

[0028] Figure 1 A system 1 is shown that is capable of performing zero verification and zero calibration of the vibration meter 5.

[0029] Figure 2 A vibration meter 5 is shown, configured to detect a measurement bias of a reference zero flow value.

[0030] Figure 3 A block diagram of a vibration meter 5 configured to detect a measurement bias of a reference zero flow value is shown, including a block diagram representation of meter electronics 20.

[0031] Figure 4 Metering electronics 20 for detecting the measurement bias of a reference zero flow value are shown.

[0032] Figure 5 Figure 500 illustrates the AGA 11 standard for tolerances related to flow rate measurements.

[0033] Figure 6 Zero verification diagram 600 is shown, which illustrates the zero verification of vibration meter 5.

[0034] Figure 7 A method 700 for detecting the measurement bias of the reference zero flow value of a vibration meter is shown. Detailed Implementation

[0035] Figures 1 to 7 The following description depicts specific examples to teach those skilled in the art how to create and use the best mode of implementation for a measurement bias that detects a reference zero flow value. Some conventional aspects have been simplified or omitted for the purpose of teaching the principles of the invention. Those skilled in the art will understand variations from these examples that fall within the scope of this specification. Those skilled in the art will understand that the features described below can be combined in various ways to form multiple variations of a measurement bias that detects a reference zero flow value. Therefore, the embodiments described below are not limited to the specific examples described below, but are limited only by the claims and their equivalents.

[0036] Figure 2 A vibration meter 5 configured to detect a measurement bias of a reference zero flow value is shown. (Example) Figure 2 As shown, the vibration meter 5 includes a sensor assembly 10 and metering electronics 20. The sensor assembly 10 responds to the mass flow rate and density of the processed material. The metering electronics 20 is connected to the sensor assembly 10 via lead 100 to provide density, mass flow rate, and temperature information, as well as other information, at port 26.

[0037] The sensor assembly 10 includes a pair of manifolds 150 and 150', flanges 103 and 103' with flange necks 110 and 110', a pair of parallel conduits 130 and 130', an actuator 180, a resistance temperature detector (RTD) 190, and a pair of pickup sensors 170l and 170r. Conduits 130 and 130' have two substantially straight inlet legs 131, 131' and outlet legs 134, 134', which converge toward each other at conduit mounting blocks 120 and 120'. Conduits 130 and 130' are bent at two symmetrical locations along their length and are substantially parallel throughout their length. Supports 140 and 140' define axes W and W' about which each conduit 130 and 130' oscillates. The legs 131, 131' and 134, 134' of conduits 130, 130' are fixedly attached to conduit mounting blocks 120 and 120', and these blocks are in turn fixedly attached to manifolds 150 and 150'. This provides a continuously closed material path through sensor assembly 10.

[0038] When flanges 103 and 103' with orifices 102 and 102' are connected to a processing line (not shown) carrying the material to be measured via inlet end 104 and outlet end 104', the material enters the inlet end 104 of the meter through orifice 101 in flange 103 and is guided through manifold 150 to conduit mounting block 120 with surface 121. Within manifold 150, the material is separated and guided through conduits 130, 130'. Upon exiting conduits 130, 130', the processed material recombines into a single stream within block 120' with surface 121' and manifold 150', and is subsequently guided to outlet end 104', which is connected to the processing line (not shown) via flange 103' with orifice 102'.

[0039] Conduits 130 and 130' are selected and properly mounted to conduit mounting blocks 120 and 120' so that they have substantially the same mass distribution, moment of inertia, and Young's modulus with respect to bending axes W--W and W'--W', respectively. These bending axes pass through struts 140 and 140'. Since the Young's modulus of the conduits varies with temperature, and this variation affects the calculation of flow rate and density, an RTD 190 is mounted to conduit 130' to continuously measure the temperature of conduit 130'. The temperature of conduit 130', and therefore the voltage appearing on RTD 190 for a given current passing through it, is controlled by the temperature of the material passing through conduit 130'. The temperature-dependent voltage appearing on RTD 190 is used by metering electronics 20 in a known manner to compensate for changes in the elastic modulus of conduits 130 and 130' due to any variations in conduit temperature. RTD 190 is connected to metering electronics 20 via lead 195.

[0040] Both conduits 130 and 130' are driven by actuator 180 in opposite directions around their respective bending axes W and W' and in a so-called first out-of-phase bending mode of a vibration meter. Actuator 180 may include any of many known devices, such as a magnet mounted to conduit 130' and a counter coil mounted to conduit 130, with alternating current passing through the counter coil to vibrate both conduits 130 and 130'. A suitable drive signal 185 is applied to actuator 180 via leads through meter electronics 20.

[0041] Metering electronics 20 receives the RTD temperature signal on lead 195 and sensor signals 165 appearing on lead 100, carrying left sensor signal 165l and right sensor signal 165r respectively. Metering electronics 20 generates a drive signal 185 appearing on the lead leading to driver 180 and causing conduits 130, 130' to vibrate. Metering electronics 20 processes the left sensor signal 165l, right sensor signal 165r, and RTD signal 195 to calculate the mass flow rate and density of the material passing through sensor assembly 10. This information, along with other information, is applied as a signal by metering electronics 20 onto path 26. A more detailed discussion of metering electronics 20 follows.

[0042] Figure 3 A block diagram of a vibration meter 5 configured to detect a measurement bias at a reference zero flow value is shown, including a block diagram representation of meter electronics 20. (See diagram for reference.) Figure 3 As shown, the metering electronics 20 are communicatively coupled to the sensor assembly 10. (Refer to the previous text.) Figure 2As described, the sensor assembly 10 includes a left pickup sensor 170l and a right pickup sensor 170r, a driver 180 and a temperature sensor 190, which are communicatively coupled to the metering electronics 20 via a communication channel 112 through a set of leads 100.

[0043] Metering electronics 20 provides a drive signal 185 via lead 100. More specifically, metering electronics 20 provides drive signal 185 to driver 180 in sensor assembly 10. Additionally, sensor signal 165, including left sensor signal 165l and right sensor signal 165r, is provided by sensor assembly 10. More specifically, in the illustrated embodiment, sensor signal 165 is provided by left pickup sensor 170l and right pickup sensor 170r in sensor assembly 10. As will be understood, sensor signal 165 is provided to metering electronics 20 via communication channel 112.

[0044] The metering electronics 20 includes a processor 210 communicatively coupled to one or more signal processors 220 and one or more memories 230. The processor 210 is also communicatively coupled to a user interface 30. The processor 210 is communicatively coupled to a host computer via a communication port on port 26 and receives power via a power port 250. The processor 210 may be a microprocessor, although any suitable processor may be employed. For example, the processor 210 may include subprocessors such as a multi-core processor, serial communication ports, peripheral interfaces (e.g., serial peripheral interfaces), on-chip memory, I / O ports, etc. In these and other embodiments, the processor 210 is configured to perform operations on received and processed signals, such as digitized signals.

[0045] Processor 210 can receive digitized sensor signals from one or more signal processors 220. Processor 210 is also configured to provide information such as phase difference, fluid characteristics in sensor assembly 10, etc. Processor 210 can provide information to a host computer via a communication port. Processor 210 can also be configured to communicate with one or more memories 230 to receive information and / or store information in one or more memories 230. For example, processor 210 can receive calibration factors and / or sensor assembly zero points (e.g., phase difference when zero flow is present) from one or more memories 230. Each of the calibration factors and / or sensor assembly zero points can be associated with the vibration meter 5 and / or sensor assembly 10, respectively. Processor 210 can use the calibration factors to process the digitized sensor signals received from one or more signal processors 220.

[0046] One or more signal processors 220 are shown including an encoder / decoder (CODEC) 222 and an analog-to-digital converter (ADC) 226. The one or more signal processors 220 can modulate analog signals, digitize modulated analog signals, and / or provide digitized signals. CODEC 222 is configured to receive sensor signals 165 from a left pickup sensor 170l and a right pickup sensor 170r. CODEC 222 is also configured to provide drive signals 185 to a driver 180. In alternative embodiments, more or fewer signal processors may be used.

[0047] As shown, sensor signal 165 is provided to CODEC 222 via signal conditioner 240. Drive signal 185 is provided to driver 180 via signal conditioner 240. Although signal conditioner 240 is shown as a single block, it may include signal conditioning components such as two or more operational amplifiers, filters such as low-pass filters, voltage-to-current amplifiers, etc. For example, sensor signal 165 can be amplified by a first amplifier, and drive signal 185 can be amplified by a voltage-to-current amplifier. Amplification ensures that the amplitude of sensor signal 165 is close to the full-scale range of CODEC 222.

[0048] In the illustrated embodiment, one or more memories 230 include read-only memory (ROM) 232, random access memory (RAM) 234, and ferroelectric random access memory (FRAM) 236. However, in alternative embodiments, one or more memories 230 may include more or fewer memories. Additionally or alternatively, one or more memories 230 may include different types of memories (e.g., volatile memory, non-volatile memory, etc.). For example, different types of non-volatile memory, such as erasable programmable read-only memory (EPROM), may be used instead of FRAM 236. One or more memories 230 may be storage devices configured to store process data such as drive signals or sensor signals, mass flow rate or density measurement results, etc.

[0049] The mass flow rate measurement results can be generated according to the following equation:

[0050]

[0051] in:

[0052] It is the measured mass flow rate;

[0053] FCF is the flow calibration factor;

[0054] Δt is the time delay of the measurement; and

[0055] Δt0 is the zero-flow time delay.

[0056] The measured time delay Δt includes the operationally derived (i.e., measured) time delay value, which includes the time delay present between the acquisition of sensor signals, such as when the time delay is due to the Coriolis effect related to the mass flow rate through the vibration meter 5. The measured time delay Δt is a direct measurement of the mass flow rate of the flowing material as it flows through the vibration meter 5. The zero-flow time delay Δt0 includes the time delay at zero flow. The zero-flow time delay Δt0 is a zero-flow value that can be determined at the factory and programmed into the vibration meter 5. The zero-flow time delay Δt0 is an exemplary zero-flow value. Other zero-flow values ​​determined under zero-flow conditions can be used, such as phase difference, time difference, etc. The value of the zero-flow time delay Δt0 may not change even when the flow conditions are changing. The mass flow rate value of the material flowing through the vibration meter 5 is determined by multiplying the difference between the measured time delay Δt and the reference zero-flow value Δt0 by a flow calibration factor FCF. The flow calibration factor FCF is proportional to the physical stiffness of the vibration meter.

[0057] Regarding density, the resonant frequency at which each conduit 130, 130' may oscillate can be a function of the square root of the spring constant of the conduit 130, 130' divided by the total mass of the conduits 130, 130' containing material. The total mass of the conduits 130, 130' containing material can be the mass of the conduits 130, 130' plus the mass of the material within the conduits 130, 130'. The mass of the material within the conduits 130, 130' is directly proportional to the density of the material. Therefore, the density of the material can be proportional to the square of the period of oscillation of the conduits 130, 130' containing the material multiplied by the spring constant of the conduits 130, 130'. Thus, by determining the period of oscillation of the conduits 130, 130' and by appropriately scaling the result, an accurate measurement of the density of the material contained in the conduits 130, 130' can be obtained. The metering electronics 20 can determine the period or resonant frequency using sensor signal 165 and / or drive signal 185. The conduits 130, 130' can oscillate in more than one vibration mode.

[0058] calibration

[0059] When the vibration meter 5 is in a no-flow or zero-flow condition, the vibration meter 5 can be calibrated using the factory zero-flow value. The user can additionally and optionally perform button calibration at any time to obtain a button zero-flow value. Additionally or alternatively, the vibration meter can automatically perform calibration to obtain an automatic zero-flow value. The zero-flow value used to measure fluid flow rate can be the factory zero-flow value, the button zero-flow value, the automatic zero-flow value, or any other suitable zero-flow value.

[0060] During the zero calibration of the vibration meter 5, measured values, saved values / constants, user settings, saved tables, etc., can be used. Calibration can monitor and compensate for the conditions of the vibration meter 5. Conditions can include user-input conditions, measurement conditions, inferred conditions, etc., without limitation. Conditions can include temperature, fluid density, flow rate, meter specifications, viscosity, Reynolds number, post-calibration compensation, etc. Furthermore, different constants, such as flow calibration factors (FCF), can be applied based on operating conditions or user preferences without limitation.

[0061] The initial zero flow value can be determined during calibration as part of the initial factory setup of the vibration meter 5. This may require placing the vibration meter 5 under no-flow or zero-flow conditions and determining the time delay, phase difference, etc., between the left sensor signal 165l and the right sensor signal 165r. The determined value is stored as the initial zero flow value in one or more memories 230 and used as the reference zero flow value. By way of example, for the above equation [1], the reference zero flow value may be the ΔT0 term, which may be the no-flow or zero-flow time delay between the left sensor signal 165l and the right sensor signal 165r. Once the reference zero flow value is determined, a flow calibration factor (FCF) can be established, which, as can be understood from the above equation [1], may be an indication of the time delay Δt of the measurement. 测量 With mass flow rate The slope of the line relating the two. The FCF can be stored in one or more memory locations 230.

[0062] Zero verification

[0063] Zero verification may include comparing a new zero flow value with a reference zero flow value. For example, the new zero flow value may be compared with a zero flow value determined at the plant (e.g., the plant zero flow value), although any suitable reference zero flow value may be used. The new zero flow value may be determined, for example, by averaging multiple zero flow value measurements taken at the point where the vibration meter 5 is installed on the processing pipeline, but as referenced above. Figure 1 This is generated during the fluid isolation described.

[0064] Comparing a new zero flow value with a reference zero flow value can include comparing multiple zero flow value measurements with the reference zero flow value. If multiple zero flow value measurements are not within the tolerance of the reference zero flow value (e.g., "predetermined limits", "zero stability value", etc.), the reference zero flow value may no longer be valid, and a new zero flow value may be stored as the reference zero flow value. If the new zero flow value is within the tolerance of the reference zero flow value, the reference zero flow value may be valid, and the new zero flow value may or may not be stored as the reference zero flow value.

[0065] However, the tolerance of the reference zero flow value can be based on the calibration of the vibration meter 5 under factory conditions, which may not be applicable to all processes. Furthermore, after installation, the vibration meter 5 is affected by installation, operating, and / or process conditions, which may differ from and be more specific than factory conditions. For example, installation conditions may cause a relatively small offset in the actual zero flow time delay of conduits 130, 130' (e.g., an offset within the tolerance of the reference zero flow value). Additionally, processes employing the vibration meter 5 may have mass flow rate measurement tolerances that require even tighter tolerances for the reference zero value.

[0066] Therefore, even if the zero flow rate measurement is within the tolerance of the reference zero flow rate, the reference zero flow rate may still be invalid for the process. For example, if the reference zero flow rate bias indicator shows that the reference zero flow rate results in a measurement bias that causes the flow rate measurement to be outside the tolerance of the flow rate measurement, then the reference zero flow rate may be invalid. This determination and evaluation of the reference zero flow rate bias indicator can be performed, either to determine whether multiple zero flow rate measurements are within the tolerance of the reference zero flow rate, or as an alternative to determining whether multiple zero flow rate measurements are within the tolerance of the reference zero flow rate.

[0067] A bias indicator for a reference zero flow value can be any indicator capable of demonstrating that the reference zero flow value causes a measurement bias. For example, a bias indicator can include a central tendency value and a discrete value associated with the zero flow value measurement. The central tendency value could be the average of the zero flow value measurements, and the discrete value could be the standard deviation of the new zero flow value measurement. In another example, a bias indicator could be the ratio (e.g., a sign ratio) of the difference between the new zero flow value measurement and the reference zero flow value to the total number of positive or negative values ​​of the new zero flow value measurements. However, any suitable bias indicator capable of reliably demonstrating that the reference zero flow value causes a measurement bias can be employed.

[0068] Zero verification can include the aforementioned and other zero verification criteria based on, for example, a specific process, fluid type, etc. For example, as described above, the vibration meter 5 can measure liquids or gases. The zero verification criteria for liquids may differ from those for gases. Zero verification criteria may differ in aspects such as tolerance or threshold value of the reference zero flow value. Therefore, the metering electronics 20 can be configured to select a zero verification criterion.

[0069] Figure 4 Metering electronics 20 for detecting measurement bias of a reference zero flow value are shown. (Example) Figure 4 As shown, the metering electronics 20 includes an interface 401 and a processing system 402. The metering electronics 20 receives vibration responses from a sensor assembly, such as sensor assembly 10. The metering electronics 20 processes the vibration responses to obtain the flow characteristics of the flowing material passing through sensor assembly 10. The metering electronics 20 can also perform checks, verifications, calibration routines, etc., to ensure accurate measurement of the flow characteristics of the flowing material.

[0070] Interface 401 can be accessed from Figure 2 and Figure 3 One of the pickup sensors 170l and 170r shown receives sensor signal 165. Interface 401 can perform any necessary or desired signal conditioning, such as formatting, amplification, buffering, etc., in any manner. Alternatively, some or all of the signal conditioning can be performed in processing system 402. Additionally, interface 401 enables communication between the meter electronics 20 and external devices. Interface 401 is capable of any form of electronic, optical, or wireless communication. Interface 401 can provide information based on vibration response. Interface 401 can communicate with digital devices, such as… Figure 3 The CODEC 222 shown is coupled in a configuration where the sensor signal includes an analog sensor signal. The digitizing device samples the analog sensor signal and digitizes it, generating a digitized sensor signal.

[0071] The processing system 402 operates the metering electronics 20 and processes flow measurement values ​​from the sensor assembly 10. The processing system 402 executes one or more processing routines, thereby processing the flow measurement values ​​to generate one or more flow characteristics. The processing system 402 is communicatively coupled to the interface 401 and configured to receive information from the interface 401.

[0072] Processing system 402 may include a general-purpose computer, a microprocessor system, logic circuits, or other general-purpose or custom-designed processing devices. Alternatively or additionally, processing system 402 may be distributed among multiple processing devices. Processing system 402 may also include any integrated or separate electronic storage medium, such as storage system 404.

[0073] The storage system 404 can store vibration meter parameters and data, software routines, constant values, and variable values. In one embodiment, the storage system 404 includes routines executed by the processing system 402 of the vibration meter 5, such as operating routine 410, zero calibration routine 420, and zero verification routine 430. The storage system can also store statistical values, such as average values, standard deviations, confidence intervals, etc.

[0074] Operating routine 410 can determine the mass flow rate value 412 and the density value 414 based on the sensor signals received from interface 401. The mass flow rate value 412 can be a frequency-independent mass flow rate value, a directly measured mass flow rate value, etc. For example, as described above, the mass flow rate can be determined using the following equation: this equation does not include frequency or frequency-related values, such as density. The mass flow rate value 412 can be determined based on the sensor signals, such as the time delay between the left and right pickup sensor signals. The density value 414 can also be determined based on the sensor signals, for example, by determining the frequency based on one or both of the left and right pickup sensor signals.

[0075] Zero calibration routine 420 can perform the aforementioned zero verification and store the initial zero value or factory zero value as a reference zero flow rate value 422. As described above, the mass flow rate value 412 can be calculated using the reference zero flow rate value 422. Zero calibration routine 420 can also determine a zero stability value and store it as a reference zero stability value 424. Additionally or alternatively, the reference zero flow rate value 422 and the reference zero stability value 424 can be determined by a calibration routine stored on and executed on an external device, such as a calibration platform that performs the initial calibration of the vibration meter 5 at the factory.

[0076] Zero-verification routine 430 can verify that the reference zero-flow value 422 is acceptable by using, for example, a reference zero-stability value 424. For example, zero-verification routine 430 can measure the zero-flow value under no-flow or zero-flow conditions of the vibration meter 5 and store the measured zero-flow value as the zero-flow value measurement 432. Zero-verification routine 430 can determine whether the zero-flow value measurement 432 is within the reference zero-stability value 424.

[0077] Additionally or alternatively, the zero-validation routine 430 may determine a bias indicator value 434 for the reference zero flow value 422. The bias indicator value 434 may indicate that the reference zero flow value 422 can cause a measurement bias in the mass flow rate value 412. As described above, the bias indicator value 434 for the reference zero flow value 422 may include a central tendency value and a discrete value associated with the zero flow value measurement 432. For example, the central tendency value may be the average of multiple differences between the zero flow value measurement 432 and the reference zero flow value 422, and the discrete value may be the standard deviation of the multiple differences about the average.

[0078] Zero-verification routine 430 can also select a zero-verification criterion. For example, zero-verification routine 430 can select a zero-verification criterion based on the fluid characteristics contained in sensor assembly 10. The zero-verification criterion may include a reference zero-stability value 424 and / or other values. For example, such as... Figure 4 As shown, the first zero-validation criterion 440 may include a first bias indicator reliability threshold 442. Therefore, the zero-validation routine 430 can determine whether the zero flow value measurement 432 is within the reference zero stability value 424, and whether the bias indicator value 434 is within the first bias indicator reliability threshold 442. In the case of using the null hypothesis as described above, the first bias indicator reliability threshold 442 may be, for example, a sign ratio of 75%, zero, or a dead zone near zero.

[0079] The zero-verification routine 430 may also select a second zero-verification criterion 450, which includes, for example, a second zero-stability value 452 and a second bias indicator reliability threshold 454. The second zero-stability value 452 may not be the same as the reference zero-stability value 424. For example, the second zero-stability value 452 may be smaller than the reference zero-stability value 424. Therefore, the second zero-stability value 452 can be used when the vibration meter 5 is used in a process requiring a zero-stability value smaller than the reference zero-stability value 424.

[0080] By way of example, for unregulated liquid transport, zero-validation routine 430 can determine whether the zero flow rate measurement 432 is within a reference zero stability value 424. For regulated liquid transport, zero-validation routine 430 can determine whether the zero flow rate measurement 432 is within a reference zero stability value 424, and whether the bias indicator value 434 is within a first bias indicator reliability threshold 442. For regulated gas transport, zero-validation routine 430 can determine whether the zero flow rate measurement 432 is within a second zero stability value 452, and whether the bias indicator value 434 is within a first bias indicator reliability threshold 442. These are merely examples, and any suitable combination of one or more tolerances to the reference zero flow rate value can be used for any suitable characteristic of the fluid.

[0081] The first bias indicator reliability threshold 442 and / or the second bias indicator reliability threshold 454 can be user-configurable. For example, a user can set the dead zone near zero to achieve a desired zero verification criterion for a particular application. Therefore, the confidence interval values ​​(described in more detail below) stored as discrete values ​​of the bias indicator value 434 can be configured by the manufacturer, and the user can configure the first bias indicator reliability threshold 442 and / or the second bias indicator reliability threshold 454 to be compared with the discrete values, or more specifically, with the confidence interval in this example. By way of illustration, for one application, the manufacturer can set a 2σ confidence interval value that can be compared with zero (i.e., no dead zone), while for more stringent applications, the user can set a dead zone value that can be compared with a 3σ confidence interval value that is comparable to zero when compared with a 2σ confidence interval value. Referring to the sign ratio, the user can set the sign ratio value as the bias indicator reliability threshold. The sign ratio value may require fewer computational resources compared to comparing the confidence interval with the dead zone to determine whether the bias indicator is sufficiently reliable. The sign ratio can also correspond to a confidence interval. For example, a 75% sign ratio value can correspond to approximately 1σ or a 68% confidence level. These and other values ​​can be set by the user and stored as a first bias indicator reliability threshold 442 and / or a second bias indicator reliability threshold 454 compared to the bias indicator value 434. The processing system 402 can also determine a first zero-validation criterion 440 or a second zero-validation criterion 450. For example, the processing system 402 can calculate the second zero-stability value 452 based on a reference zero-stability value 424. In a particular example, the second zero-stability value 452 can be calculated by multiplying the reference zero-stability value 424 by, for example, 0.5 to scale the reference zero-stability value 424 to the second zero-stability value 452. Additionally or alternatively, the first bias indicator reliability threshold 442 and / or the second bias indicator reliability threshold 454 can be calculated similarly.

[0082] The ratio used to scale the first zero-validation criterion 440 or the second zero-validation criterion 450 can be based on fluid characteristics. For example, the ratio could be a ratio of an error band associated with the fluid's expected low or high flow rate, whether the fluid is a gas or a liquid, or whether the fluid's density is greater than or less than a density threshold. In a particular example, this ratio could be determined by dividing the error band associated with the fluid's expected high flow rate by the error band associated with the fluid's expected low flow rate. See below. Figure 5 Let's discuss this example.

[0083] Figure 5 Figure 500 illustrates the AGA 11 standard for tolerances related to flow rate measurements. Figure 5As shown, Figure 500 includes a measured flow rate axis 510 and a percentage error axis 520. The measured flow rate axis 510 can be in any suitable unit, such as kilograms per minute (kg / min). The measured flow rate axis 510 ranges from zero to the maximum flow rate Q. 最大 The percentage error axis 520 ranges from -1.60 to 1.60, although any suitable range and / or unit may be used.

[0084] Figure 500 also includes an error curve 530 illustrating an exemplary error-flow rate relationship for a Coriolis meter. For each corresponding flow rate, error curve 530 has associated repeatability bars illustrating the range to which the measured value is expected to fall. As can be seen, error curve 530 decreases with increasing flow rate, where measurement stability improves significantly. As can also be seen, repeatability bars and error increase with decreasing measured flow rate. The increase in repeatability bars and error may be due to the increased contribution of nonlinear effects to the flow rate measurement. Other error curves may be employed, including those with smaller increases, or those where the error is primarily linear, for example, due to a reference zero flow value.

[0085] Figure 500 also includes an error limiting band 540 with a low flow error limiting band 540a and a normal flow error limiting band 540b. The low flow error limiting band 540a and the normal flow error limiting band 540b are symmetrical about the zero error rate axis. The low flow error limiting band 540a corresponds to the minimum flow rate Q. 最小 With threshold flow rate Q t The flow rate range between [specific values]. Normal flow error limit band 540b is for the threshold flow rate Q. t With maximum flow rate Q 最大 The flow rates are between [specific values]. As can be seen, the low flow error limit band 540a has a larger error limit value than the normal flow error limit band 540b.

[0086] To meet the AGA 11 standard, Coriolis flow meters, such as the aforementioned vibration meter 5, can have an error rate within the error limit band 540. However, because the low flow error limit band 540a has a larger error limit value than the normal flow error limit band 540b, many users choose to operate at flow rates below the threshold flow rate Q. t The Coriolis meter is not operated at this time. Therefore, the operating regulation ratio or effective regulation ratio of such a Coriolis flow meter is determined by the threshold flow rate Q. t Limitation rather than by minimum flow rate Q 最小Limitations. Due to various reasons, including measurement bias associated with the reference zero flow value, the error curve 530 may have a non-zero error rate. For example, in the above equation [1], the zero flow time delay Δt0 may be an inaccurate zero flow value of the Coriolis flow meter. Therefore, the measured flow rate It may include measurement bias caused by the reference zero flow value.

[0087] Reference Figure 5 Error curve 530 can be improved by reducing the error rate represented by it. For example, error curve 530 can be shifted closer to the zero error axis by reducing the measurement bias caused by the reference zero flow value 422. Additionally, other routines, such as calibration to determine the FCF, can compensate for the nonlinear contribution of error curve 530 at low flow rates. Therefore, by shifting and flattening error curve 530, the flow rate decreases to the minimum Q. 最小 In this case, error curve 530 can be within the normal flow error limit band 540b. Therefore, for the threshold flow rate Q... t With minimum flow rate Q 最小 For flow rates between these parameters, a narrower error limit band can be used.

[0088] Measurement bias associated with the reference zero flow value can be eliminated by performing zero calibration. Figure 1 Zero calibration can be performed in the field by isolating the vibration meter 5 and performing zero flow value calibration. More specifically, the vibration meter 5 can be fluidly isolated such that the flow through the vibration meter 5 is zero, and therefore it can be assumed that the measured zero flow value represents zero flow.

[0089] The difference between the measured zero flow value and the reference zero flow value can be proportional to the measurement bias caused by an incorrect reference zero flow value. To compensate for this measurement bias, a new measured zero flow value can replace the reference zero flow value that can be stored in the metering electronics 20. However, as can be understood, the measured zero flow value may not be perfectly accurate. The following describes a method for determining that the measured zero flow value is a reliable zero flow value and therefore an accurate measurement of the zero flow value of the sensor assembly 10.

[0090] Figure 6 Zero-verification diagram 600 is shown, illustrating the zero-verification of the vibration meter 5. (See diagram 600 for details.) Figure 6As shown, the zero-verification graph 600 includes a sample axis 610 and a zero-flow-value axis 620. The sample axis 610 is unitless but is illustrated in the time domain. Therefore, each scale mark on the sample axis 610 represents a sample time. The zero-flow-value axis 620 is shown as being represented by a time delay term Δt0, which is in units of time, although any suitable zero-flow-value, such as a phase difference, can be used. The unit of the zero-flow-value axis 620 can be nanoseconds, although any suitable unit, such as a phase- or angle-dependent unit, can be used.

[0091] Zero-validation diagram 600 also shows a reference zero-flow value 630 and a corresponding zero-stability value 640. The zero-stability value 640 is shown as a tolerance band with respect to the reference zero-flow value 630. The zero-stability value 640 represents a validation criterion, which can be a first zero-validation criterion. In other words, if all measured zero-flow values ​​fall within the band representing the zero-stability value 640, the vibration meter 5 can be considered good for a first application associated with the first zero-validation criterion. The first zero-validation criterion can be associated with liquid measurements in unregulated transport.

[0092] The zero-verification diagram 600 also includes a zero-flow value measurement 650 represented by dots. The zero-flow value measurement 650 can be represented as shown above. Figure 1 The zero flow rate measurement value is obtained. As can be seen, the zero flow rate measurement value 650 is always greater than the reference zero flow rate value 630. Therefore, the zero flow rate measurement value 650 indicates that the reference zero flow rate value 630 can cause a measurement bias in the flow rate measurement value obtained according to the above equation [1]. The average value 650a and confidence interval 650b determined based on the zero flow rate measurement value 650 are also shown, which will be discussed in more detail below.

[0093] A bias indicator can demonstrate that the difference between the reference zero flow value 630 and the measured zero flow value 650 is due to inaccuracy of the reference zero flow value 630. A bias indicator for the reference zero flow value 630 can include any one or more values ​​that indicate that a new zero flow value can reduce or eliminate the measurement bias in the flow rate measurement caused by the reference zero flow value 630. The following discussion provides examples of bias indicators for the reference zero flow value 630.

[0094] The sign ratio is the ratio of the number of positive or negative values, or signs, to the total number of values. If the calculated sign is positive, the sign ratio can be called a positive sign ratio; or if the calculated sign is negative, the sign ratio can be called a negative sign ratio. Figure 6As shown, all the differences between the zero flow rate measurement 650 and the reference zero flow rate 630 are positive. Therefore, the positive sign ratio of the multiple differences is 100%, and the negative sign ratio is 0%. If any sign ratio is greater than the bias indicator reliability threshold, the average value determined based on the zero flow rate measurement 650 can be used as a new reference zero flow rate value to reduce or eliminate the measurement bias caused by the inaccuracy of the reference zero flow rate value 630. Additionally or alternatively, the new reference zero flow rate value can be determined by performing zero calibration.

[0095] By way of example, the sign ratio bias indicator reliability threshold can be a predetermined value of 75%. All zero flow value measurements 650 are greater than the reference zero flow value 630. Therefore, as described above, the sign ratio of the multiple differences between the zero flow value measurements 650 and the reference zero flow value 630 is 100% positive. This ratio is greater than 75%, and therefore the average value 650a calculated from the zero flow value measurements 650 can be used as the reference zero flow value to reduce or eliminate the measurement bias caused by the reference zero flow value 630.

[0096] Statistical methods for calculating the probabilities of results can be used to calculate bias indicators in vibration meters. For example, P-statistics and T-statistics can be used to test whether a given dataset satisfies a null hypothesis. Rejecting the null hypothesis does not determine whether a condition exists in the vibration meter, but it does determine that the lack of a condition is erroneous. In the case of zero validation, the null hypothesis can be limited to: "The current zero flow value is the same as the reference zero flow value." If this null hypothesis is rejected, it can be assumed that the current zero flow value is not the same as the reference zero flow value, and therefore the reference zero flow value will cause a measurement bias in the flow rate measurement.

[0097] By way of explanation, the t-value can be calculated using the following equation in a t-test:

[0098]

[0099] in:

[0100] μ0 is a specified value;

[0101] It is the sample mean;

[0102] s is the sample standard deviation; and

[0103] n is the sample size.

[0104] In the context of zero validation, μ0 is the reference zero flow value, such as the zero flow time delay Δt0 mentioned in the above equation [1]. The zero flow value measurement can be used to calculate the sample average. The sample standard deviation s is used for comparison with the reference zero flow value. The number of zero flow value measurements is the sample size n. The t-test usually also includes degrees of freedom, which are limited to n-1 for the above equation [2].

[0105] As mentioned above, the t-test can be used to test for a null hypothesis. For null testing, this null hypothesis can be limited to the sample mean. Is it equal to the reference zero flow value? To test the null hypothesis, a p-value can be calculated using a known distribution of t-values. To test the null hypothesis, the p-value is compared to a significance level α. The significance level α is typically set to a small value, such as 0.01, 0.05, or 0.10. If the p-value is less than or equal to the significance level α, the null hypothesis is rejected due to the alternative hypothesis. Since the null hypothesis is constrained to "the current zero validation result has the same mean as the baseline zero validation result," the alternative hypothesis is that the current zero validation does not have the same mean, and therefore, a change has occurred in the meter.

[0106] However, calculating the P-value may be difficult when computational resources are limited. For example, the P-value can be calculated on a computer workstation with an operating system and statistical software, but it may be difficult to calculate in an embedded system. The aforementioned measuring electronics 20 can be an embedded system with limited computational resources.

[0107] Therefore, a confidence interval using the limited computational resources of the measuring electronics 20 can be used instead of the P-value. Thus, the confidence interval can be calculated using embedded code on the measuring electronics 20. For example, the measuring electronics 20 can have the current zero flow value and the zero standard deviation value stored in two registers. As can be understood, the aforementioned t-value can be calculated using the current zero flow value using the significance level α and degrees of freedom. By way of example, the significance level α can be set to 0.01, i.e., a confidence level of 99%. The number of zero validation tests can be set to 10. Therefore, the degrees of freedom are determined to be 9. The two-tailed Student's t-value can be calculated using the Student's t-value function as shown below, based on the significance level α and degrees of freedom:

[0108] t 学生,99,9 =tinv(.01,9)=3.25. [3]

[0109] The standard deviation of the measured zero flow value can be determined. The standard error can also be calculated, and it is defined as follows:

[0110]

[0111]

[0112] The confidence interval range can be calculated using the standard error and t-value determined above:

[0113] CI 范围 =Standard error·t 学生,99,9 [5]

[0114] CI 范围 =Standard error · 3.25.

[0115] Finally, the confidence interval can be calculated using the average of the zero flow values ​​and the confidence interval range, as shown below:

[0116] CI = Zero value 平均值 ±CI 范围 [6]

[0117] In the example above, a 99% confidence level can be used to calculate a confidence interval that can be compared to the reliability threshold of the bias indicator. For example, a confidence interval can be used to test for a null hypothesis by determining whether the confidence interval includes 0.0. If the confidence interval does include 0.0, the null hypothesis is not rejected, and the zero-validation indicator reference zero flow value does not cause a measurement bias. If the confidence interval does not include 0.0, the null hypothesis can be rejected, and a zero-validation error can be sent. The average of the zero flow value measurement of 650 can be saved as a new reference zero flow value, and a new calibration can be performed, etc. Therefore, a confidence interval can be used to test for a null hypothesis at the desired confidence level.

[0118] In addition to the confidence interval, the bias dead zone can be limited to near zero. In a t-test, this bias dead zone is a value near zero, because a small bias with small variations (which would otherwise cause the confidence interval check to reject the hypothesis) does not reject the hypothesis. Therefore, the bias dead zone can be set to a value that reduces the number of erroneous bias indicators in the reference zero flow value.

[0119] In the example of a confidence interval compared to zero, the bias dead zone is the range around zero, where the null hypothesis is not rejected if zero is not within the confidence interval, but a portion of the bias dead zone is within the confidence interval. Mathematically, this test can be expressed as whether the mean zero flow value is less than the bias dead zone. Or, using the above terminology: if Where db 偏置 If it is a bias dead zone, then the null hypothesis cannot be rejected.

[0120] Bias dead zones can be implemented independently or in combination with other dead zones. For example, they can be implemented by combining them with variable dead zones. In one example, the variable dead zone can be based on the database (db). 变化 =db 偏置 / t 学生,99,8 To determine, where db 变化This is the variable dead zone. The variable dead zone can be compared to the standard deviation of the zero flow value to determine whether the null hypothesis should be rejected. In the example, the bias dead zone can be compared as discussed above, and the variable dead zone can be compared to the standard deviation of the zero flow value as follows: If And if s <db 变化 If the null hypothesis is not found, then the null hypothesis cannot be rejected. The aforementioned tests can be used after the null hypothesis has already been rejected using the confidence interval check. Alternatively, if... And if s <db 变化 The average value of zero flow Set to zero, and the change in zero flow value equals the change dead zone.

[0121] When the bias indicator indicates that the reference zero flow value 630 can be replaced by a zero flow value that reduces or eliminates the measurement bias caused by the reference zero flow value 630, the reference zero flow value 630 can be updated, replaced, etc. Therefore, the metering electronics 20 can be configured to update or replace the reference zero flow value 630 by, for example, saving the average value of the zero flow value measurement 650, initiating a zero calibration routine to determine a new zero flow value, etc. A zero calibration routine for obtaining a new reference zero flow value may be more advantageous than the zero flow value measurement 650 because the zero calibration routine can include additional quality control steps / features. Furthermore, additional calibration steps, such as recalculating the FCF, can be performed.

[0122] By reducing or eliminating the measurement bias, and other routines that reduce or eliminate the nonlinear contribution at low flow rates, according to Figure 5 The error curve shown in Figure 530 shows an improved error curve that can be reduced to a minimum flow rate Q. 最小 At the given flow rate, the flow rate falls within the normal flow error limit band of 540b or even a more stringent error limit band. Therefore, for flow rates less than the threshold flow rate Q... t For this application, a zero-verification standard associated with the normal flow error limit band 540b can be used. As can be understood, this can improve the effective control ratio of the vibration meter 5 (i.e., increase to the maximum flow rate Q). 最大 With minimum flow rate Q 最小 (ratio).

[0123] Specific applications with lower performance requirements may be associated with less stringent zero-validation standards. An example application with lower performance requirements could be the unregulated transport of liquids. Applications or processes with higher performance requirements may have associated zero-validation standards that include, for example, zero-stability values ​​smaller than those used in the less stringent zero-validation standards described above. An example high-performance application could be the regulated transport of gases, such as the regulated transport of natural gas at points of consumption.

[0124] More stringent zero validation criteria may also include a bias indicator reliability threshold for a bias indicator used to reference the zero flow value. For example, a central tendency and discrete value associated with the zero flow value measurement 650 may be determined, and this central tendency and discrete value may be compared to a reference zero flow value. In one example, the central tendency associated with the zero flow value measurement 650 may be the average of multiple differences between the zero flow value measurement 650 and the reference zero flow value. The discrete value associated with the zero flow value measurement 650 may be, for example, a confidence interval 650b about the average 650a of multiple differences between the zero flow value measurement 650 and the reference zero flow value. As described above, the confidence interval 650b may be determined using confidence levels (e.g., 99%, 95%, etc.). The confidence interval 650b may be compared to a bias indicator reliability threshold, which, in the null hypothesis t-test described above, may be zero or a dead zone near zero.

[0125] Zero validation criteria can be determined by the metering electronics 20 based on the characteristics of the fluid. For example, the zero validation criterion scale can also be determined based on whether the fluid is a gas or a liquid. For instance, if the zero stability value 640 is associated with an unregulated delivery of a liquid, a more stringent zero validation criterion for a regulated delivery of a gas can be calculated by scaling the zero stability value 640 to a zero validation criterion scale of, for example, 0.5—although any suitable value can be used. Other characteristics of the fluid, such as the measured density, can be used to determine the zero validation criterion scale.

[0126] More specifically, the density of the fluid contained in the vibration meter 5 can be measured and compared with a density value threshold. If the measured density is less than the density value threshold, a first zero-verification criterion can be selected. If the measured density is greater than the density value threshold, a second zero-verification criterion can be selected. The first zero-verification criterion is suitable for higher-performance applications, and the second zero-verification criterion is suitable for lower-performance applications. The density value threshold can be selected, input, or chosen by the user. More density value thresholds can be used. For example, there can be two or more density value thresholds that define a range of density values, each associated with an additional zero-verification criterion value. Therefore, two or more zero-verification criteria can be selected.

[0127] One of the zero-validation threshold criteria can be stored in memory or scaled according to another zero-validation criterion. For example, refer to Figure 5The error limit band 540 has different values ​​based on the fluid flow rate. More specifically, the low flow error limit band 540a has a value that is approximately twice that of the normal flow error limit band 540b. As can be understood, the zero-validation criterion associated with the low flow error limit band 540a can be more or less stringent depending on the specific application, and the value of the zero-validation criterion can be proportional to the ratio of the low flow error limit band 540a to the normal flow error limit band 540b.

[0128] therefore, Figure 6 The zero stability value 640 shown can be scaled (e.g., multiplied by a zero verification standard ratio) depending on whether the vibration meter 5 is used for a higher-performance or lower-performance application. For example, if Figure 6 The zero stability value 640 shown is associated with the low flow error limit band 540a. Therefore, in the metering electronics 20, the zero stability value 640 can be multiplied by 0.5 to determine a smaller zero stability value with respect to the reference zero flow value 630. As an example, the purpose of doing this might be to achieve accurate measurement within the normal flow error limit band 540b at lower flow rates, so as to... t The flow rate is improved to a lower flow rate value, thereby expanding the range of usable flow rates for the meter in the application. For example, from... Figure 5 Understandably, the zero-validation ratio can depend on the expected flow rate of the fluid.

[0129] As described above, the zero-verification criterion can be constituted by or include a reference zero-flow value, such as a bias indicator reliability threshold for reference zero-flow value 630. The bias indicator can be compared to the bias indicator reliability threshold. The bias indicator can be determined using, for example, values ​​of central tendency and dispersion associated with the zero-flow value measurement 650. Figure 6 As shown, the central tendency is the mean 650a and the dispersion is the confidence interval 650b.

[0130] Additionally or alternatively, an appropriate zero-verification criterion can be selected based on the characteristics of the fluid in the vibration meter 5. For example, the zero-verification criterion can be selected based on determining whether the application is a regulated delivery of gas. In this example, the selection criterion could be determining whether the measured density is less than a gas density threshold and whether the vibration meter 5 is used for regulated delivery. If both are true, a more stringent zero-verification criterion can be selected.

[0131] As can be understood, the selection of the zero-verification criterion can be automated. More specifically, the user may only need to store a value in metering electronics 20 that indicates the vibration meter 5 is being used for regulatory delivery. Metering electronics 20 can thus be configured to determine, for example, the liquid being measured by the vibration meter 5 in the regulatory delivery, and therefore, during zero-verification, a smaller zero-stability value with respect to the reference zero-flow rate can be used without determining a bias indicator of the reference zero-flow rate value.

[0132] Figure 7 A method 700 for detecting the measurement bias of a reference zero flow value of a vibration meter is shown. The vibration meter can be the vibration meter 5 described above, although any suitable vibration meter can be used. In step 710, method 700 can measure multiple zero flow values ​​of a sensor assembly, such as sensor assembly 10 described above. In step 720, method 700 can compare the multiple zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value. The vibration meter can perform the steps of method 700.

[0133] Accordingly, the vibration meter can be configured to use zero flow values ​​to measure the flow rate of a fluid. For example, the vibration meter may include a sensor assembly and metering electronics communicatively coupled to the sensor assembly. The metering electronics may be configured to measure multiple zero flow values ​​of the sensor assembly and compare the multiple zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value.

[0134] Metering electronics configured to compare multiple zero flow values ​​with a reference zero flow value may include metering electronics configured to determine multiple differences between the multiple zero flow values ​​and the reference zero flow value. For example, each measured zero flow value may be subtracted from the reference zero flow value to determine the corresponding difference.

[0135] A bias indicator referencing a zero flow value may include a sign ratio of multiple differences. For example, the sign ratio may include the count of either positive or negative differences divided by the total count of the multiple differences. Alternatively, the bias indicator may be a central tendency value of multiple differences and a reliability indicator of the central tendency value. A reliability indicator of the central tendency value may be a discrete value of the central tendency value.

[0136] The vibration meter 5, metering electronics 20, and method 700 described above can detect measurement bias of a reference zero flow value. For example, metering electronics 20 can be configured to measure multiple zero flow values ​​of sensor assembly 10 and compare the multiple zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value. As mentioned above, the multiple zero flow values ​​may be within the zero stability value of the reference zero flow value, but still indicate that the reference zero flow value has caused a measurement bias in a measurement, such as a flow rate measurement.

[0137] By detecting a measurement bias in the reference zero flow rate value, a new reference zero flow rate value can be used to replace it, which may cause no measurement bias or only a small bias. Reducing or eliminating the measurement bias in the reference zero flow rate value can improve the measurement of a vibration meter. For example, the measurement may be within tighter tolerances associated with the process or application. By way of example, a reference zero flow rate value causing a measurement bias might be suitable for unregulated liquid deliveries but not for regulated gas deliveries with tighter tolerances for flow rate measurements.

[0138] The detailed description of the above embodiments is not an exhaustive description of all embodiments contemplated by the inventors to fall within the scope of this specification. In fact, those skilled in the art will recognize that certain elements of the above embodiments can be combined or eliminated differently to produce other embodiments, and such other embodiments fall within the scope and teachings of this specification. It will also be apparent to those skilled in the art that the above embodiments can be combined, in whole or in part, to produce additional embodiments within the scope and teachings of this specification.

[0139] Therefore, although specific embodiments have been described herein for illustrative purposes, various equivalent modifications are possible within the scope of this specification, as will be recognized by those skilled in the art. The teachings provided herein can be applied to other methods for configuring a vibration meter to detect a measurement bias of a reference zero flow value, and not only to the embodiments described above and shown in the accompanying drawings. Therefore, the scope of the above embodiments should be determined by the following claims.

Claims

1. A metering electronics (20) configured to detect a measurement bias of a reference zero flow value, the metering electronics (20) comprising: Interface (401), which is communicatively coupled to a sensor assembly (10) containing fluid. as well as A processing system (402) communicatively coupled to the interface (401) is configured to measure a plurality of zero flow values ​​of the sensor assembly (10), compare the plurality of zero flow values ​​with a reference zero flow value to determine a bias indicator of the reference zero flow value, and determine a plurality of differences between the plurality of zero flow values ​​and the reference zero flow value, wherein the bias indicator of the reference zero flow value includes a sign ratio of the plurality of differences.

2. The meter electronics (20) of claim 1, wherein, The sign ratio comprises the count of one of the positive and negative values ​​among the plurality of differences divided by the total count of the plurality of differences.

3. The meter electronics (20) of claim 1, wherein, The bias indicator is the central tendency value of the plurality of differences and a reliability indicator of the central tendency value.

4. The meter electronics (20) of claim 3, wherein, The reliability indicator of the central tendency value is the discrete value of the central tendency value.

5. The meter electronics (20) of claim 1, wherein, The processing system (420) is also configured to compare the bias indicator with a bias indicator reliability threshold.

6. A method for detecting a measurement bias of a reference zero flow value, the method comprising: Measure multiple zero flow values ​​of the sensor assembly; Compare the plurality of zero flow values ​​with a reference zero flow value; The bias indicator that determines the reference zero flow value based on comparison, and Determine multiple differences between the plurality of zero flow values ​​and the reference zero flow value, wherein the bias indicator of the reference zero flow value includes the sign ratio of the plurality of differences.

7. The method of claim 6, wherein, The sign ratio comprises the count of one of the positive and negative values ​​among the plurality of differences divided by the total count of the plurality of differences.

8. The method of claim 6, wherein, The bias indicator is the central tendency value of the plurality of differences and a reliability indicator of the central tendency value.

9. The method according to claim 8, wherein, The reliability indicator of the central tendency value is the discrete value of the central tendency value.

10. The method of claim 6, further comprising comparing the bias indicator with a bias indicator reliability threshold.

11. A vibration meter (5) configured to detect a measurement bias of a reference zero flow value, the vibration meter (5) comprising: A sensor assembly (10) comprising fluid; as well as Measuring electronics (20) communicatively coupled to the sensor assembly (10), the measuring electronics (20) being configured as a measuring electronics according to any one of claims 1 to 5.

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