Excitation and measurement of twist mode in a coriolis flowmeter

Abstract

A Coriolis flowmeter (5) is provided having a sensor assembly (10) in communication with meter electronics (20). The sensor assembly (10) comprises a flowtube (103, 103'). A driver (104) is in communication with at least one flowtube (103, 103'), and receives a drive signal and oscillates the flowtube (103, 103') in a first bending mode. First and second pickoffs (105, 105') are in communication with the flowtube (103, 103'). The meter electronics (20) receives oscillatory signals generated from the first and second pickoffs (105, 105'). The driver (104) and the first and second pickoffs (105, 105') communicate with meter electronics (20) over a signal path (204). A module (200) temporarily exchanges communication paths between the first pickoff (105) and the driver (104), and the first pickoff (105) receives the drive signal and the driver (104) generates oscillatory signals sent to the meter electronics (20).

Description

[0001] EXCITATION AND MEASUREMENT OF TWIST MODE IN A CORIOLIS FLOWMETER

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to Coriolis flowmeters and related methods of operation, and more particularly, to improved flowmeter measurements.

[0004] STATEMENT OF THE PROBLEM

[0005] Vibrating conduit sensors, such as Coriolis mass flowmeters and vibrating densitometers, typically operate by detecting motion of a vibrating conduit that contains a flowing material. Properties associated with the material in the conduit, such as mass flow, density and the like, can be determined by processing measurement signals received from motion transducers associated with the conduit. The vibration modes of the vibrating material-filled system generally are affected by the combined mass, stiffness, and damping characteristics of the containing conduit and the material contained therein. Such flowmeters are disclosed in U.S. Pat. Nos. 4,109,524 of Aug. 29, 1978, 4,491,025 of Jan. 1, 1985, and Re. 31,450 of Nov. 29, 1983, all to J. E. Smith et al., which are incorporated by reference.

[0006] A typical Coriolis mass flowmeter includes one or more conduits that are connected inline in a pipeline or other transport system and convey material, e.g., fluids, slurries, emulsions, and the like, in the system. Each conduit may be viewed as having a set of natural vibration modes, including for example, simple bending, torsional, radial, and coupled modes. The operation of Coriolis flowmeters can be described using mathematical formulas, as more fully described in U.S. Patents No. 7,441,469 and 7,706,987 which are both assigned on their face to Micro Motion, Inc. and are hereby incorporated by reference.

[0007] In a typical Coriolis mass flow measurement application, each flow tube is driven to oscillate at resonance in one or more of these natural modes. Material flows into the flowmeter from a connected conduit on the inlet side of the flowmeter, is directed through the flow tube or tubes, and exits the flowmeter through the outlet side. The natural vibration modes of the vibrating material filled system are defined in part by the combined mass of the flow tubes and the material flowing within the flow tubes. The motion of the conduit is measured at points spaced along the conduit. Excitation is typically provided by an actuator, e.g., an electromechanical device, such as a voice coil-type driver, that perturbs the conduit in a periodic fashion. Two transducers (or pickoff sensors) are typically employed to measure a vibrational response of the flow conduit or conduits and are typically located at positions upstream and downstream of the actuator. Mass flow rate may be determined by measuring time delay or phase differences between motions at the spaced-apart transducer locations, wherein the time delay or phase difference are caused by Coriolis forces in the flowing material. The Coriolis forces are generated by the directional change in the moving fluid due to the tube vibrations. These Coriolis forces are exerted on the sensor tube and produce perturbations in the vibrational motion. These perturbations will cause one end of a flowtube to lead and the other end to lag, creating a phase delay in the leading and lagging vibration sensor signals.

[0008] The pickoff sensors arc connected to meter electronics (or other instrumentation) that receives the signals from the pickoff sensors and processes the signals to derive a mass flow rate measurement, among other things. To generate a mass flow rate measurement, the meter electronics can convert the measured phase delay into a time delay using the driving frequency of the vibration. The mass flow rate passing through the flow tubes is directly proportional to this time delay (At), as given by: m = FCF * At (1)

[0009] The (FCF) term is a flow calibration factor that considers various meter characteristics such as meter stiffness, ambient temperature, and meter construction and geometry, for example. However, in actual operation at a no-flow condition, the time delay (At) may comprise a non-zero value and must be compensated for in the equation to accurately measure flows. Consequently, the mass flow rate may be better represented as: m = FCF * [At — Ato] (2)

[0010] The (Ato) term is a time delay correction value at a no-flow condition, also called a meter zero term. The meter zero term (Ato) may generate a no-flow vibrational phase shift due to positional, mass, and / or damping asymmetries between the driver and the pickoff sensor or sensors. The meter zero term (Ato) may also exist due to modal interactions of a pickoff sensor with the driving mode of the flowtube or tubes. The meter zero term (Ato) may exist due to pickoff sensor and driver design. The meter zero term (Ato) may exist due to environmental temperature and changes in the temperature.

[0011] In Coriolis mass flow meters, twist mode oscillations of a flow conduit can provide information about process conditions such as pressure, viscosity, speed of sound, composition, and others. However, measuring the twist mode frequency can be difficult without specifically exciting the twist mode. Since, in most Coriolis flowmeters, the driver is positioned in the center of a top portion (see, e.g. FIG. 1) of at least one conduit, exciting with the driver is not an effective option because it is generally located at a node of the twist mode.

[0012] Therefore, there is a need in the art for a flowmeter and related method for exciting twist mode vibrations of flow conduits with a driver in the standard twist mode nodal position to allow for pressure, viscosity, speed of sound, composition, and other measurements to be more accurately ascertained.

[0013] SUMMARY OF THE INVENTION

[0014] A Coriolis flowmeter is provided comprising a sensor assembly in communication with meter electronics, wherein the sensor assembly comprises at least one flowtube configured to receive a fluid therethrough. A driver is in communication with the at least one flowtube, wherein the driver is operable to receive a drive signal from the meter electronics and oscillate the at least one flowtube in at least a first bending mode. A first pickoff and a second pickoff are in communication with the at least one flowtube, wherein the meter electronics is operable to receive oscillatory signals generated from the first and second pickoffs, wherein the driver and the first and second pickoffs communicate with meter electronics over a signal path. A module in the signal path is operable to temporarily exchange communication paths between the first pickoff and the driver, such that the first pickoff is operable to receive the drive signal from the meter electronics and the driver is operable to generate signals sent to the meter electronics.

[0015] A Coriolis flowmeter is provided comprising a meter electronics and a sensor assembly further comprising a driver, a first pickoff and a second pickoff The module comprises at least one relay operable to connect to, and interrupt, a signal path between the meter electronics and the sensor assembly, wherein the signal path comprises a drive signal injection path in communication with the driver, a first pickoff reception path in communication with the first pickoff, and a second pickoff reception path in communication with the second pickoff, wherein the at least one relay is operable to temporarily physically exchange the drive signal injection path with the first pickoff reception path such that the first pickoff is operable to receive a drive signal from the meter electronics and the driver is operable to send signals to the meter electronics.

[0016] A method of operating a flowmeter having meter electronics is provided. A sensor assembly of the flowmeter is provided, the sensor assembly comprising a driver, a first pickoff, and a second pickoff, each in communication with one or more flowtubes. A signal path between the meter electronics and the sensor assembly is provided that comprises a drive signal injection path in communication with the driver, a first pickoff reception path in communication with the first pickoff, and a second pickoff reception path in communication with the second pickoff. The drive signal injection path is temporarily connected to the first pickoff, and the first pickoff reception path is temporarily connected to the driver.

[0017] ASPECTS OF THE INVENTION

[0018] According to an aspect, a Coriolis flowmeter comprises a sensor assembly in communication with meter electronics, wherein the sensor assembly comprises at least one flowtube configured to receive a fluid therethrough. A driver is in communication with the at least one flowtube, wherein the driver is operable to receive a drive signal from the meter electronics and oscillate the at least one flowtube in at least a first bending mode. A first pickoff and a second pickoff are in communication with the at least one flowtube, wherein the meter electronics is operable to receive oscillatory signals generated from the first and second pickoffs, wherein the driver and the first and second pickoffs communicate with meter electronics over a signal path. A module in the signal path is operable to temporarily exchange communication paths between the first pickoff and the driver, such that the first pickoff is operable to receive the drive signal from the meter electronics and the driver is operable to generate signals sent to the meter electronics.

[0019] Preferably, the first pickoff is operable to excite the at least one flowtube in a twist mode when the communication paths are exchanged. Preferably, the module comprises at least one relay, wherein the at least one relay inteiTupts a signal path between the meter electronics and the sensor assembly.

[0020] Preferably, the module comprises an integral portion of the meter electronics.

[0021] According to an aspect, a Coriolis flowmeter comprises a meter electronics and a sensor assembly further comprising a driver, a first pickoff and a second pickoff The module comprises at least one relay operable to connect to, and interrupt, a signal path between the meter electronics and the sensor assembly, wherein the signal path comprises a drive signal injection path in communication with the driver, a first pickoff reception path in communication with the first pickoff, and a second pickoff reception path in communication with the second pickoff, wherein the at least one relay is operable to temporarily physically exchange the drive signal injection path with the first pickoff reception path such that the first pickoff is operable to receive a drive signal from the meter electronics and the driver is operable to send signals to the meter electronics.

[0022] Preferably, the first pickoff is operable to excite the at least one flowtube in a twist mode when the drive signal is received by the first pickoff.

[0023] Preferably, at least one relay that interrupts a signal path between the meter electronics and the sensor assembly.

[0024] Preferably, the least one relay further comprises a first throw being normally closed, a second throw being normally open, a third throw being normally closed, a fourth throw being normally open, a fifth throw being normally closed, a sixth throw being normally open, a seventh throw being normally closed, and an eighth throw being normally open. A first pole is in communication with the first and second throws, the first pole connected to a positive terminal of the driver, a second pole is in communication with the third and fourth throws, the second pole connected to a negative terminal of the driver, a third pole is in communication with the fifth and sixth throws, the third pole connected to a positive terminal of the first pickoff, and a fourth pole is in communication with the seventh and eighth throws, the fourth pole connected to a negative terminal of the first pickoff. A positive lead of the drive signal injection path is in electrical communication with the first throw, and a negative lead of the drive signal injection path is in electrical communication with the third throw, a positive lead of the pickoff reception path is in electrical communication with the second throw, and a negative lead of the pickoff reception path is in electrical communication with the fourth throw, the positive lead of the pickoff reception path is also in electrical communication with the fifth throw, and the negative lead of the pickoff reception path is also in electrical communication with the seventh throw, and the positive lead of the pickoff reception path is also in electrical communication with the sixth throw, and the negative lead of the pickoff reception path is in electrical communication with the eighth throw. The drive signal injection path is in communication with the driver and the first pickoff reception path is in communication with the first pickoff when the relay is in the normally closed position, and wherein the drive signal injection path is in communication with the first pickoff and the first pickoff reception path is in communication with the driver when the relay is in the normally open position.

[0025] Preferably, the at least one relay is housed inside the meter electronics.

[0026] According to an aspect a method of operating a flowmeter having meter electronics is provided. A sensor assembly of the flowmeter is provided, the sensor assembly comprising a driver, a first pickoff, and a second pickoff, each in communication with one or more flowtubes. A signal path between the meter electronics and the sensor assembly is provided that comprises a drive signal injection path in communication with the driver, a first pickoff reception path in communication with the first pickoff, and a second pickoff reception path in communication with the second pickoff. The drive signal injection path is temporarily connected to the first pickoff, and the first pickoff reception path is temporarily connected to the driver.

[0027] Preferably, the method comprises driving the driver to induce a first bending mode oscillation in the one or more flow tubes, and receiving, by the meter electronics, oscillatory signals from the first and second pickoffs.

[0028] Preferably, the method comprises driving the first pickoff to induce a twist mode oscillation in the one or more flow tubes, and receiving, by the meter electronics, oscillatory signals from the driver and the second pickoff.

[0029] Preferably, the method comprises positioning the driver in a node as defined by the twist mode oscillation.

[0030] Preferably, the method comprises interrupting at least a portion of the signal path with one or more relays, and actuating the one or more relays.

[0031] Preferably, the method comprises driving the first pickoff to induce a twist mode oscillation in the one or more flow tubes, sweeping drive frequencies sent to the first pickoff, measuring the pickoff response with at least one of the driver and the second pickoff, and determining a first resonant frequency of the sensor assembly.

[0032] Preferably, the method comprises determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the first resonant frequency of the sensor assembly.

[0033] Preferably, the method comprises changing a fluid property of a fluid flowing through the flowmeter, determining a second resonant frequency of the sensor assembly associated with the changed fluid property, and determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the second resonant frequency of the sensor assembly.

[0034] Preferably, the method comprises at least one of correlating and identifying at least one of a related fluid property and an environmental property using the eigenvector associated with the changed fluid property.

[0035] Preferably, the method comprises identifying an environmental property changed during operation of the flowmeter, determining a third resonant frequency of the sensor assembly associated with the changed environmental property, and determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the third resonant frequency of the sensor assembly.

[0036] Preferably, the method comprises at least one of correlating and identifying at least one of a related fluid property and an environmental property with the eigenvector associated with the changed environmental property.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The same reference number represents the same element on all drawings. The drawings are not necessarily to scale.

[0039] FIG. 1 shows a vibratory flowmeter according to an embodiment;

[0040] FIG. 2 shows meter electronics for a vibratory flowmeter according to an embodiment;

[0041] FIG. 3 represents a vibratory flowmeter having curved flowtubes wherein tire two parallel curved flowtubes are vibrated in a first bending mode;

[0042] FIG. 4 represents the vibratory flowmeter wherein the two parallel curved flowtubes are vibrated in a twist mode; FIG. 5 is a flow chart illustrating a method of operating a flowmeter according to an embodiment; and

[0043] FIG. 6 illustrates a flowmeter signal path having a module according to an embodiment.

[0044] DETAILED DESCRIPTION

[0045] FIGS. 1-6 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

[0046] FIG. 1 illustrates an example of a flowmeter 5 in the form of a Coriolis flowmeter comprising a sensor assembly 10 and one or more meter electronics 20. The one or more meter electronics 20 are connected to the sensor assembly 10 to measure a characteristic of a flowing material, such as, for example, density, pressure, mass flow rate, volume flow rate, totalized mass flow, temperature, and other information.

[0047] The sensor assembly 10 includes a pair of flanges 101 and 101’, manifolds 102 and 102’, and flowtubes 103 and 103’. Manifolds 102, 102’ are affixed to opposing ends of the flowtubes 103, 103’. The manifolds 102, 102’ are typically multi-piece assemblies. Flanges 101 and 101' of the present example are affixed to manifolds 102 and 102’. Manifolds 102 and 102’ of the present example are affixed to opposite ends of spacer 106. The spacer 106 maintains the spacing between manifolds 102 and 102’ in the present example to prevent undesired vibrations in flowtubes 103 and 103’. In embodiments, no space 106 is present. The flowtubes 103 and 103’ extend outwardly from the manifolds 102 and 102’ in a parallel fashion. When the sensor assembly 10 is inserted into a pipeline system which carries the process material, the material enters sensor assembly 10 via an inlet pipe 120 through flange 101, passes through inlet manifold 102 where the total amount of material is directed to enter flowtubes 103 and 103’, flows through flowtubes 103 and 103' and back into outlet manifold 102’ where it exits the sensor assembly 10 through the flange 101’.

[0048] The sensor assembly 10 includes a driver 104. The driver 104 is affixed to flowtubes 103 and 103’ in a position where the driver 104 can vibrate the flowtubes 103, 103’ in the drive mode. More particularly, the driver 104 includes a first driver component (not shown) affixed to flowtube 103 and a second driver component (not shown) affixed to flowtube 103’. The driver 104 may comprise one of many well-known arrangements, such as a magnet mounted to the flowtube 103 and an opposing coil mounted to the flowtube 103’.

[0049] In the present example, the drive mode may be the first out of phase bending mode and the flowtubes 103 and 103’ would be selected and appropriately mounted to inlet manifold 102 and outlet manifold 102’ so as to provide a balanced system having substantially the same mass distribution, moments of inertia, and clastic moduli about bending axes W-W and W’-W’, respectively. In the present example, where the drive mode is the first out of phase bending mode, the flowtubes 103 and 103’ are driven by the driver 104 in opposite directions about their respective bending axes W-W and W’-W’. 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 lead 110, and passed through the coil to cause both flowtubes 103, 103’ to oscillate.

[0050] The sensor assembly 10 shown includes a pair of pickoffs 105, 105’ that are affixed to flowtubes 103, 103’. More particularly, a first pickoff component (not shown) is located on flowtube 103, and a second pickoff component (not shown) is located on flowtube 103'. In the embodiment depicted, the pickoffs 105, 105' may be electromagnetic detectors, for example — pickoff magnets and pickoff coils that produce pickoff signals that represent the velocity and position of the flowtubes 103, 103’. For example, the pickoffs 105, 105’ may supply pickoff signals to the one or more meter electronics via pathways 111, 111’. Those of ordinary skill in the art will appreciate that the motion of the flowtubes 103, 103’ is proportional to certain characteristics of the flowing material, for example, the mass flow rate and density of the material flowing through the flowtubes 103, 103’.

[0051] In the flowmeter illustrated in FIG. 1 , the one or more meter electronics 20 receive the pickoff signals from the pickoffs 105, 105’. Path 26 provides an input and an output means that allows one or more meter electronics 20 to interface with an operator. The one or more meter electronics 20 measure at least one characteristic of a flowing material, such as, for example, a phase difference, a frequency, a time delay, a density, a mass flow rate, a volume flow rate, a totalized mass flow, a temperature, a meter verification, pressure, and other information. More particularly, the one or more meter electronics 20 receive one or more signals, for example, from pickoffs 105, 105’ and one or more temperature sensors 107, such as a resistive temperature detector (RTD), and use this information to measure a characteristic of a flowing material.

[0052] In embodiments, driver 104 in is communication with the at least one flowtube 103, 103’, wherein the driver 104 is positioned nodally when the at least one flowtube 103, 103’ is excited in a twist mode, and wherein the driver 104 is operable to receive a drive signal from the meter electronics 20 and oscillate the at least one flowtube 103, 103’ in at least a first bending mode. The first pickoff 105 and a second pickoff 105' arc in communication with the at least one flowtube 103, 103’. The meter electronics 20 is operable to receive oscillatory signals generated from the first and second pickoffs 105, 105'. The driver 104 and the first and second pickoffs 105, 105’ communicate with meter electronics 20 over a signal path 204. This will be referred to as the “bend” operation.

[0053] A module 200 is provided that can interrupt the signal path 204 to, upon receiving a signal to do so, temporarily exchange communication paths between the first pickoff 105 and the driver 104, such that the first pickoff 105 is operable to receive the drive signal from the meter electronics 20 and the driver 104 is operable to generate signals sent to the meter electronics 20. This will be referred to as the “twist” operation. In twist operation, the first pickoff 105 drives the sensor assembly 10 in an off-center manner, which causes excitation of both the first bending mode and a structural twist mode.

[0054] Voice coil-type transducers, such as those used for the driver 104 and first and second pickoffs 105, 105’, are operable to generate an oscillatory motion representing an A / C signal that is provided to the transducer. Furthermore, when the transducer is oscillated, it will generate an A / C signal.

[0055] The bend mode and twist mode shapes each have unique frequencies associated with their shapes. When the driver 104 is initially driven, whether in bend or twist operation, the meter electronics 20 sweeps the excitation frequency through a predetermined band of frequencies and locks in and drives at the frequency having the highest pickoff response. During bend operation, with the diver is located at the center location of at least one flowtube 103, 103’, the frequency with greatest response is the first bending mode. This is the frequency that the meter electronics 20 locks onto, and the resultant first bend mode shape realized.

[0056] When the excitation is off center, such as when the flowmeter 5 is in twist operation, the pickoffs see responses at frequencies associated with first bend mode, twist, and other modes as well. The off-center excitation causes more or less relative excitation of the various modes depending on how far off-center the transducer being driven is, which in the instant embodiments, is the off-center first pickoff 105 location, which is repurposed to drive the flow tube(s) 103, 103’ for twist operation.

[0057] When the first pickoff’ s 105 operation is repurposed to that of a driver, the location of the first pickoff 105, which is driving the flow tube(s) 103, 103’, is proximate an antinode of the twist mode in its resonant shape. Therefore, when the meter electronics 20 sweeps frequencies on start-up, the response at the second pickoff’ s 105’ location is much higher at the frequency corresponding to the structural twist mode shape as comparted to bend operation. In this case the flow tubes 103, 103’ vibrate with a twisting shape even when there is no flow because the twist mode is being specifically excited at its natural frequency. This allows the frequencies excited due to twist mode operation to be accurately measured.

[0058] The difference in frequency during operation of either the first bending or twist mode shape is due to the fundamental resonant frequencies of the sensor assembly 10. Each frequency has a different mode shape associated with it. Being able to measure the instantaneous twist mode frequency allows for insights into characteristics of process conditions including pressure, speed of sound, viscosity, etc. Additionally, the twist mode frequency and its ratio to the first bend mode correlates to a flowmeter’ s flow calibration factor (FCF), and therefore is used to monitor FCF changes. In this respect, this ratio is used to implement meter verification diagnostics. For the majority of Coriolis flowmeters, the driver is located at the node of the twist mode, so as to minimally excite said mode. However, as in present embodiments, if the driver 104 is located off-center, the flowmeter 5 can still be driven in the first bend mode, albeit not as efficiently. In this case, the flowtubes 103, 103’ may be resonated in either the first bend and / or first twist when the driver 104 is remapped to the first pickoff 105 location. Locking onto the first bend frequency, the second pickoff 105’ and the original driver 104 (now remapped to act as a pickoff) are used to determine delta-t in an embodiment. In an embodiment, the twist mode is alternatively driven while having off- resonant excitation of the first bend mode.

[0059] In an embodiment, the first pickoff 105 is excited in a multi-mode that simultaneously drives both the first bend mode and twist mode. This allows measuring both first bend mode and first twist mode frequencies and also allows simultaneously measuring flow in the first bend mode.

[0060] In an embodiment, matrices 318 are developed by the sensor assembly’s mass, stiffness, damping, etc. The set of resonant frequencies determined by the first bending and twist mode are treated as eigenvalues. The eigenvalues of a matrix (or system of matrices) 318 may be determined by solving the characteristic equation for the matrix / matriccs 318. Those solutions arc the set of eigenvalues. Evaluating the matrix / matrices 318 at any one of those eigenvalues will result in finding the eigenvector associated with the given eigenvalue. Therefore, sets of eigenvectors may be solved for.

[0061] Knowing the frequency (eigenvalue) adds more known values regarding the structure of the sensor assembly and how it responds to its environment. Each of these structural modal frequencies will change due to fluid properties (VOS, viscosity) and environmental properties (pressure / temp / etc.). Depending on which modal frequencies are monitored, those modes may respond independently to the new property / environment, or they may respond similarly, or some combination of both. In an embodiment, the use of additional identified modal frequencies is used to isolate responses to given fluid properties, and thus provide data points that allow correlations and / or identification of related fluid properties and / or environmental properties of interest to be calculated. In an embodiment, the use of additional identified modal frequencies is used to isolate responses to given environmental properties, and thus provide data points that allow correlations and / or identification of related fluid properties and / or environmental properties of interest.

[0062] FIG. 2 is a general block diagram of the meter electronics 20 according to an embodiment. It should be noted that electronics for a stand-alone diagnostic tool may have similar architecture. In operation, the flowmeter 5 provides various measurement values that may be outputted including one or more of a measured or averaged value of density, mass flow rate, volume flow rate, individual flow component mass and volume flow rates for multi-phase flow, and total flow rate, including, for example, both volume and mass flow of individual flow components. Meter electronics 20 and stand-alone electronics may comprise a user interface wherein a user may input data and / or receive outputted data.

[0063] The flowmeter 5 sensor assembly 10 receives vibrational signals generated by meter electronics 20. A vibrational response of the sensor assembly 10 is received and processed by the meter electronics 20 to generate one or more fluid measurement values. The values can be monitored, recorded, saved, totaled, and / or output.

[0064] The meter electronics 20 includes an interface 301, a processing system 303 in communication with the interface 301, and / or a storage system 304. Although these components are shown as distinct blocks, it will be understood to those skilled in the art that the meter electronics 20 is comprised of various combinations of integrated and / or discrete components in embodiments.

[0065] The interface 301 may be configured to electrically couple to the driver(s) 104, pickoff sensors 105, 105', and temperature sensors 107, and to exchange signals therewith, for example. The interface 301 may be further configured to communicate over the communication path 26, such as to external devices.

[0066] The processing system 303 can comprise any manner of processing system. The processing system 303 is configured to retrieve and execute stored routines in order to operate the flowmeter 5. The storage system 304 can store routines including a general meter routine 305, a drive gain routine 313, sum registers 317, and / or a twist mode routine 315. The storage system 304 can store measurements, received values, working values, and other information. In some embodiments, the storage system stores a mass flow (m) 321, a density (p) 325, a viscosity (p) 323, a temperature (T) 324, a pressure 309, a drive gain 306, a pressure loss 308, meter par ameters both measured or stored 311, process fluid properties 314 and any other variables known in the art. The routines 305, 313, 315, may comprise any signal noted as well as other variables known in the art. In embodiments, portions of the storage system 304 may store / accumulate values related to the flowmeter, and also provide routine data, such as the matrices 318 portion of the storage system 304, for example. Other measurement / processing routines are contemplated and are within the scope of the description and claims. The general meter routine 305 can produce and store fluid quantifications and flow measurements. These values can comprise substantially instantaneous measurement values or can comprise totalized, accumulated, and / or averaged values over any time period, and may be time stamped in some embodiments. For example, the general meter routine 305 can generate mass flow measurements and store them in the mass flow 321 storage of the storage system 304, for example. Similarly, the general meter routine 305 can generate density measurements and store them in the density 325 storage of the storage system 304, for example. The mass flow 321 and density 325 values are determined from the vibrational response, as previously discussed and as known in the art. The mass flow and other measurements can comprise a substantially instantaneous value, can comprise a sample, can comprise an averaged value over a time interval, or can comprise an accumulated value over a time interval. The time interval may be chosen to correspond to a block of time during which certain fluid conditions arc detected, for example, a liquid-only fluid state, or alternatively, a fluid state including liquids, entrained gas, and / or solids, solutes, and combinations thereof. In addition, other mass and volume flow and related quantifications are contemplated and are within the scope of the description and claims.

[0067] FIGS. 3-4 show examples of various flowtube vibration or normal modes in a Coriolis flowmeter. The vibration modes are dependent on the sensor geometry, the flow tube shape and material, and the presence of associated structures. The vibration modes of FIGS. 3-4 will have analogues in every sensor geometry. It should be understood that the various vibration modes shown in FIGS. 3-4 are not necessarily to scale and may be exaggerated for the purpose of illustration. It should also be understood that the examples are simplified for clarity and in actual operation, the vibrational motion of a flowtube may comprise a superposition of multiple vibration modes.

[0068] FIG. 3 shows a simplified depiction of a flowtube vibrating in a first bend mode. In the first bend mode, the top of the flowtube is displaced in a z-direction, wherein the portion of the flowtube above the bend axis W will subsequently flex and vibrate in the -z and +z directions. Two nodes for each conduit in the first bend mode are found on the bend axis W. Neither the driver 104, nor the pickoffs 105, 105’ are located at a nodal position. FIG. 4 shows a simplified depiction of a flowtube vibrating in a first twist mode. In the first twist mode, the two ends of the top portion are displaced oppositely in the -z and +z directions. The first twist mode has three nodes. Two nodes for each conduit in the first bend mode are found on the bend axis W. The third node (N) is located about the center of the top portion of each conduit. This is collocated with the driver 104. The pickoffs 105, 105’ are located proximate anti-nodal positions.

[0069] FIG. 5 illustrates a method 300 of operating a flowmeter 5 according to an embodiment. The flowmeter 5 may have any of the features described herein. In embodiments, the method is at least partially effectuated by utilizing the twist mode routine 315.

[0070] In step 302, a sensor assembly 10 of a flowmeter 5 is provided at least partially as described herein.

[0071] In step 304, a signal path 204 is provided between the meter electronics 20 and the sensor assembly 10. The signal path 204 is divided into at least a drive signal injection path 206 in communication with the driver 104, a first pickoff reception path 208 in communication with the first pickoff 105. In an embodiment, a second pickoff reception path 208’ is in communication with the second pickoff 105. These paths 206, 208, 208’ allow signals to travel to and from the various elements of the sensor assembly 10 and the meter electronics 20. Other paths are considered that provide communication to / from temperature sensors, strain gauges, piezoelectric sensors, etc., in embodiments.

[0072] In step 306, and with further reference to an embodiment of the module of FIG. 6, the signal path 204 is interrupted by the module 200, and the drive signal injection path 206 between the meter electronics 20 and the driver 104 is rerouted to provide a signal to the first pickoff 105, and the first pickoff reception path 208 is rerouted to receive a signal from the driver 104. In an embodiment, the module 200 and related switching mechanism is integral to the meter electronics 20. In an embodiment, at least one connector 205 connects the module 200 to the sensor assembly 10 and / or to meter electronics 20. In an embodiment, the sensor assembly 10 and / or the meter electronics 20 are hardwired to the module 200. In an embodiment, portions of the signal path are hardwired, and portions utilize connectors 205. In an embodiment, the signal path 204 is interrupted with a mechanical switch. In an embodiment, the signal path 204 is interrupted with at least one relay 202. In embodiments, the module 200 comprises the relay. The relay may be secured to a printed circuit board (PCB) in an embodiment. The module comprises a PCB with the relay in an embodiment. In an embodiment, the module 200 comprises a wire loom having a relay bundled therein, either with or without a printed circuit board (PCB). A signal from meter electronics 20 actuates the relay 202. In embodiments, the module 200 is internal to the flowmeter and / or sensor assembly 10. In embodiments, the module 200 is external to the flowmeter and / or sensor assembly 10. In embodiments, the module 200 is built into meter electronics 20. The module 200, in embodiments, is retrofittable into an already- assembled flowmeter 5, thus conferring the ability to additionally operate the flowmeter 5 in a state wherein the driver 104 and first pickoff 105 are capable of temporarily exchanging functional roles.

[0073] In an embodiment, at least one relay 202 is an electromechanical switch for controlling electrical circuit continuity by opening and closing contacts. The relay 202 comprises a coil 201, at least one mechanically movable contact (i.c. pole) 228, 230, 232, 234 in communication with the coil 201, switching points (i.e. contacts, throws) 212, 214, 216, 218, 220, 222, 224, 226, 228, and a spring that biases the pole(s) when an electrical current is not provided to the coil 201. In an embodiment, the relay 202 comprises a solenoid to actuate contacts. When a cunent is applied to a coil 201, a magnetic field is induced that overcomes the spring bias, and attracts a pole 228, 230, 232, 234, causing it to move between associated throws 212, 214, 216, 218, 220, 222, 224, 226, 228. The contacts within the relay 202 are at least one of normally open (N / O), normally closed (N / C), and common. N / O contacts are in an open position by default and closed when the coil 201 is energized. N / C contacts are in a closed position by default, and open when the relay is energized. The spring biases the related pole to the N / C throw. Thus, when the coil 201 is energized, the magnetic field attracts the pole 228, 230, 232, 234, causing the pole 228, 230, 232, 234 to move from a normally closed throw to a normally open throw, thus completing or breaking the circuit associated with a particular pole 228, 230, 232, 234 within the relay.

[0074] In an embodiment, the at least one relay 202 comprises a first N / C throw 212, a second N / O throw 214, a third N / C throw 216, a fourth N / O throw 218, a fifth N / C throw 220, a sixth N / O throw 222, a seventh N / C throw 224, and an eighth N / O throw 226. A first pole 228 is operable to be in communication with the first and second throws 212, 214. A second pole 230 is operable to be in communication with the third and fourth throws 216, 218. A third pole 232 is operable to be in communication with the fifth and sixth throws 220, 222 A fourth pole 234 is operable to be in communication with the seventh and eighth throws 224, 226. This is one embodiment of configuring one or more relays, and should not limit the configuration of the at least one relay 202 for embodiments provided herein. Different pole and throw schemes are considered, as will be understood in the art.

[0075] In connecting the module 200 to the flowmeter, the first pole 228 is connected to a positive terminal 104+ of the driver 104, and the second pole 230 is connected to a negative terminal 104- of the driver 104. The third pole 232 is connected to a positive terminal 105+ of the first pickoff 105, and the fourth pole 234 is connected to a negative terminal 105- of the first pickoff 105.

[0076] A positive lead 206+ of the drive signal injection path 206 is in electrical communication with the first throw 212, and a negative lead 206- of the drive signal injection path 206 is in electrical communication with the third throw 216. A positive lead 208+ of the pickoff reception path 208 is in electrical communication with the second throw 214, and a negative lead 208- of the pickoff reception path 208 is in electrical communication with the fourth throw 218. The positive lead 208+ of the pickoff reception path 208 is also in electrical communication with the fifth throw 220. The negative lead 208- of the pickoff reception path 208 is also in electrical communication with the seventh throw 224. The positive lead 206+ of the drive signal injection path 206 is also in electrical communication with the sixth throw 222. The negative lead 206- of the drive signal injection path 206 is in electrical communication with the eighth throw 226.

[0077] The drive signal injection path 206 is therefore in communication with the driver 104, and the first pickoff reception path 208 is in communication with the first pickoff 105 when the relay is in the normally closed position. In this configuration, the driver 104 is driven to induce a first bending mode oscillation in the one or more flow tubes 103, 103’, while oscillatory signals from the first and second pickoffs 105, 105’ are received by the meter electronics 20.

[0078] Upon actuation of the at least one relay or relays 202, at least a portion of the signal path 204 is remapped. Thus, the drive signal injection path 206 is connected to the first pickoff 105 and the first pickoff reception path 208 is connected to the driver 104 when the relay is in the normally open position. In this configuration, the first pickoff 105 is driven to induce a twist mode oscillation in the one or more flow tubes 103, 103', and the meter electronics 20 receives oscillatory signals from the driver 104 and the second pickoff 105’.

[0079] It should be noted that, in an embodiment, the connections are reversed, such that the throws indicated to be N / C are instead N / O, and the throws indicated to be N / O are instead N / C. This changes the default state of the relay or relays 202 and requires that the coil 201 be energized to operate in the manner described above and illustrated in FIG. 6. It should also be noted that the first pickoff 105 is located proximate an inlet side of the flowmeter 5 in an embodiment. Conversely, in other embodiments, the first pickoff 105 is located proximate an outlet side of the flowmeter 5.

[0080] Electromechanical relays 202 having coils 201 and using a movable spring-biased pole are described herein. However, it will be understood that solid-state relays that rely on semiconductors to control a switching mechanism arc also considered in embodiments, as are hybrid relays, reed relays, microprocessor-based relays, any other kind of relay known in the art, and combinations thereof. Two relays are illustrated in the drawings, but one relay or more than two relays are considered in embodiments. In an embodiment, additional relays are provided, the drive signal injection path 206 is connected to the second pickoff 105’ and the second pickoff reception path 208’ is connected to the driver

[0081] 104 when the relay is in the normally open position. Therefore, either the first pickoff

[0082] 105 or the second pickoff 105’ may be repurposed to drive the flow tubes 103, 103’, thus allowing a choice between driving the pickoff located proximate the outlet side of the flowmeter or the pickoff located proximate the inlet side.

[0083] 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 invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the abovedescribed embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention. Accordingly, the scope of the invention should be determined from the following claims.

Claims

What is Claimed is:

1. A Coriolis flowmeter (5) comprising: a sensor assembly (10) in communication with meter electronics (20), wherein the sensor assembly (10) comprises at least one flowtube (103, 103’) configured to receive a fluid therethrough; a driver (104) in communication with the at least one flowtube (103, 103’), wherein the driver (104) is operable to receive a drive signal from the meter electronics (20) and oscillate the at least one flowtube (103, 103’) in at least a first bending mode; a first pickoff (105) and a second pickoff (105’) in communication with the at least one flowtube, wherein the meter electronics (20) is operable to receive oscillatory signals generated from the first and second pickoffs (105, 105’), wherein the driver (104) and the first and second pickoffs (105, 105’) communicate with meter electronics (20) over a signal path (204); a module (200) in the signal path (204) operable to temporarily exchange communication paths between the first pickoff (105) and the driver (104), such that the first pickoff (105) is operable to receive the drive signal from the meter electronics (20) and the driver (104) is operable to generate signals sent to the meter electronics (20).

2. The Coriolis flowmeter (5) of claim 1, wherein the first pickoff (105) is operable to excite the at least one flowtube (103, 103’) in a twist mode when the communication paths are exchanged.

3. The Coriolis flowmeter (5) of any one of claims 1 and 2, wherein the module comprises at least one relay (202), wherein the at least one relay (202) interrupts a signal path (204) between the meter electronics (20) and the sensor assembly (10).

4. The Coriolis flowmeter (5) of any one of claims 1 to 3, wherein the module (200) comprises an integral portion of the meter electronics (20).

5. A module (200) for interfacing with a Coriolis flowmeter (5), the Coriolis flowmeter (5) comprising a meter electronics (20) and a sensor assembly (10) furthercomprising a driver (104), a first pickoff (105) and a second pickoff (105’), the module (200) comprising: at least one relay (202) operable to connect to, and interrupt, a signal path (204) between the meter electronics (20) and the sensor assembly (10), wherein the signal path (204) comprises a drive signal injection path (206) in communication with the driver (104), a first pickoff reception path (208) in communication with the first pickoff (105), and a second pickoff reception path (208') in communication with the second pickoff (105’); wherein the at least one relay (202) is operable to temporarily physically exchange the drive signal injection path (206) with the first pickoff reception path (208) such that the first pickoff (105) is operable to receive a drive signal from the meter electronics (20) and the driver (104) is operable to send signals to the meter electronics (20).

6. The module (200) for interfacing with a Coriolis flowmeter of claim 5, wherein the first pickoff (105) is operable to excite the at least one flowtube (103, 103’) in a twist mode when the drive signal is received by the first pickoff (105).

7. The module (200) for interfacing with a Coriolis flowmeter of any one of claims 5 and 6, comprising at least one relay (202) that interrupts a signal path (204) between the meter electronics (20) and the sensor assembly (10).

8. The module (200) for interfacing with a Coriolis flowmeter of claim 7, comprising: the least one relay (202) further comprising: a first throw (212) being normally closed; a second throw (214) being normally open; a third throw (216) being normally closed; a fourth throw (218) being normally open; a fifth throw (220) being normally closed; a sixth throw (222) being normally open; a seventh throw (224) being normally closed;an eighth throw (226) being normally open; a first pole (228) in communication with the first and second throws (212, 214), the first pole (228) connected to a positive terminal (104+) of the driver (104); a second pole (230) in communication with the third and fourth throws (216, 218), the second pole (230) connected to a negative terminal (104-) of the driver (104); a third pole (232) in communication with the fifth and sixth throws (220, 222), the third pole (232) connected to a positive terminal (105+) of the first pickoff (105); a fourth pole (234) in communication with the seventh and eighth throws (224, 226), the fourth pole (234) connected to a negative terminal (105-) of the first pickoff (105); and wherein: a positive lead (206+) of the drive signal injection path (206) is in electrical communication with the first throw (212), and a negative lead (206-) of the drive signal injection path (206) is in electrical communication with the third throw (216); a positive lead (208+) of the pickoff reception path (208) is in electrical communication with the second throw (214), and a negative lead (208-) of the pickoff reception path (208) is in electrical communication with the fourth throw (218); the positive lead (208+) of the pickoff reception path (208) is also in electrical communication with the fifth throw (220), and the negative lead (208-) of the pickoff reception path (208) is also in electrical communication with the seventh throw (224); the positive lead (208+) of the pickoff reception path (208) is also in electrical communication with the sixth throw (222), and the negative lead (208-) of the pickoff reception path (208) is in electrical communication with the eighth throw (226); and wherein, the drive signal injection path (206) is in communication with the driver (104) and the first pickoff reception path (208) is in communication with the first pickoff (105) when the relay (202) is in the normally closed position, and wherein the drive signal injection path (206) is in communication with the first pickoff (105) and the first pickoff reception path (208) is in communication with the driver (104) when the relay (202) is in the normally open position.

9. The module (200) for interfacing with a Coriolis flowmeter of any one of claims 5 to 8, wherein the at least one relay (202) is housed inside the meter electronics (20).

10. A method of operating a flowmeter having meter electronics, comprising: providing a sensor assembly of the flowmeter, the sensor assembly comprising a driver, a first pickoff, and a second pickoff, each in communication with one or more flowtubes; providing a signal path between the meter electronics and the sensor assembly that comprises a drive signal injection path in communication with the driver, a first pickoff reception path in communication with the first pickoff, and a second pickoff reception path in communication with the second pickoff; temporarily connecting the drive signal injection path to the first pickoff; and temporarily connecting the first pickoff reception path to the driver.

11. The method of operating the flowmeter of claim 10, comprising driving the driver to induce a first bending mode oscillation in the one or more flow tubes, and receiving, by the meter electronics, oscillatory signals from the first and second pickoffs.

12. The method of operating the flowmeter of any one of claims 10 and 11 , comprising driving the first pickoff to induce a twist mode oscillation in the one or more flow tubes, and receiving, by the meter electronics, oscillatory signals from the driver and the second pickoff.

13. The method of operating the flowmeter of any one of claims 10 to 12, comprising positioning the driver in a node as defined by the twist mode oscillation.

14. The method of operating the flowmeter of claim 10, comprising: interrupting at least a portion of the signal path with one or more relays; and actuating the one or more relays.

15. The method of operating the flowmeter of any one of claims 10 to 14, comprising: driving the first pickoff to induce a twist mode oscillation in the one or more flow tubes; sweeping drive frequencies sent to the first pickoff; measuring the pickoff response with at least one of the driver and the second pickoff; determining a first resonant frequency of the sensor assembly.

16. The method of operating the flowmeter of any one of claims 10 to 15, comprising determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the first resonant frequency of the sensor assembly.

17. The method of operating the flowmeter of claim 16, comprising: changing a fluid property of a fluid flowing through the flowmeter; determining a second resonant frequency of the sensor assembly associated with the changed fluid property; and determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the second resonant frequency of the sensor assembly.

18. The method of operating the flowmeter of claim 17, comprising at least one of correlating and identifying at least one of a related fluid property and an environmental property using the eigenvector associated with the changed fluid property.

19. The method of operating the flowmeter of claim 16, comprising: identifying an environmental property changed during operation of the flowmeter; determining a third resonant frequency of the sensor assembly associated with the changed environmental property; and determining an eigenvector associated with an eigenvalue, wherein the eigenvalue comprises the third resonant frequency of the sensor assembly.

20. The method of operating the flowmeter of claim 19, comprising at least one of correlating and identifying at least one of a related fluid property and an environmental property with the eigenvector associated with the changed environmental property.

Images