Patent Description:
Vibrating sensors, such as for example, vibrating densitometers and Coriolis flowmeters are generally known, and are used to measure mass flow and other information related to materials flowing through a conduit in the flowmeter. Exemplary Coriolis flowmeters are disclosed in <CIT>, <CIT>, and <CIT>, and also in <CIT> and <CIT>. These flowmeters have meter assemblies with one or more conduits of a straight or curved configuration. Each conduit configuration in a Coriolis mass flowmeter, for example, has a set of natural vibration modes, which may be of simple bending, torsional, or coupled type. Each conduit can be driven to oscillate at a preferred mode. When there is no flow through the flowmeter, a driving force applied to the conduit(s) causes all points along the conduit(s) to oscillate with identical phase or with a small "zero offset", which is a time delay measured at zero flow.

As material begins to flow through the conduit(s), Coriolis forces cause each point along the conduit(s) to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized driver position, while the phase at the outlet leads the phase at the centralized driver position. Pickoffs on the conduit(s) produce sinusoidal signals representative of the motion of the conduit(s). Signals output from the pickoffs are processed to determine the time delay between the pickoffs. The time delay between the two or more pickoffs is proportional to the mass flow rate of material flowing through the conduit(s).

A meter electronics connected to the driver generates a drive signal to operate the driver and also to determine a mass flow rate and/or other properties of a process material from signals received from the pickoffs. The driver may comprise one of many well-known arrangements; however, a magnet and an opposing drive coil have received great success in the flowmeter industry. An alternating current is passed to the drive coil for vibrating the conduit(s) at a desired conduit amplitude and frequency. It is also known in the art to provide the pickoffs as a magnet and coil arrangement very similar to the driver arrangement.

The amount of Coriolis force is directly proportional to the mass flow rate of the fluid flowing through the tube. The resonant frequency of vibration of the Coriolis mass flowmeter is influenced by the stiffness of the tube. Most corrections to Coriolis mass flowmeters are based on how the tube's stiffness changes with process and/or environmental conditions. (e.g., pressure and temperature). When the fluid flowing through the tube stops acting as a single mass (i.e., fluid at the center of the flow stream is not flowing at the same rate as the fluid next to the tube wall), additional secondary effects may be observed. This is referred to as a viscosity effect. Reynolds number is used to define the flow profile in a pipeline where this effect is most prevalent and the viscosity of the fluid is used to calculate Reynolds number. Accordingly, there is a need to correct for viscosity effects. The challenge is to develop a correction method that does not use viscosity, or number based on a viscosity measurement, such as the Reynolds number, or equipment in addition to the Coriolis mass flow meter.

According to an aspect, a system (<NUM>, <NUM>) for determining a non-viscosity correlation parameter for correcting a measured flow rate for viscosity effects of a fluid in a vibratory meter (<NUM>) comprises a sensor assembly (<NUM>); and a meter electronics (<NUM>) communicatively coupled to the sensor assembly (<NUM>), the meter electronics (<NUM>) being configured to: receive sensor signals from the sensor assembly (<NUM>); determine a non-viscosity correlation parameter based on the sensor signals, the non-viscosity correlation parameter being comprised of a fluid velocity-to-mass flow rate ratio or a vibrating frequency ratio.

Preferably, the meter electronics (<NUM>) is further configured to correlate the non-viscosity correlation parameter to a viscosity of a fluid in the sensor assembly (<NUM>).

Preferably, the meter electronics (<NUM>) is further configured to correlate the non-viscosity correlation parameter with a viscosity of one or more, preferably two or more fluids.

Preferably, the meter electronics (<NUM>) is further configured to determine a fluid flow rate; and correct the fluid flow rate based on the non-viscosity correlation parameter, said non-viscosity correlation parameter being correlated with a viscosity value.

Preferably, the meter electronics (<NUM>) is further configured to correlate the non-viscosity correlation parameter to an error percentage of a fluid flow rate of the fluid in the sensor assembly (<NUM>).

Preferably, the system (<NUM>, <NUM>) further comprises a viscometer (<NUM>, <NUM>) communicatively coupled to the meter electronics (<NUM>), said viscometer (<NUM>, <NUM>) being configured to measure the viscosity of the fluid and provide the measured viscosity to the meter electronics (<NUM>).

According to an aspect, a method for determining a non-viscosity correlation parameter for correcting a measured flow rate for viscosity effects of a fluid in a vibratory meter, comprises receiving sensor signals from a sensor assembly; determining a non-viscosity correlation parameter based on the sensor signals, the non-viscosity correlation parameter being comprised of a fluid velocity-to-mass flow rate ratio or a vibrating frequency.

Preferably, the method further comprises correlating the non-viscosity correlation parameter to a viscosity of a fluid in the sensor assembly (<NUM>).

Preferably, the method further comprises correlating the non-viscosity correlation parameter to a viscosity of one or more, preferably two or more fluids.

Preferably, the method further comprises determining a fluid flow rate; and correcting the fluid flow rate based on the non-viscosity correlation parameter, said non-viscosity correlation parameter being correlated with a viscosity value.

Preferably, the method further comprises correlating the non-viscosity correlation parameter to an error percentage of the measured flow rate and correlating the error percentage to a viscosity of the fluid in the sensor assembly.

<FIG> and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of embodiments of correcting a measured flow rate for viscosity effects. 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 present description. As a result, the embodiments described below are not limited to the specific examples described below, but only by the claims and their equivalents.

A system and method for correcting a measured flow rate for viscosity effects of a fluid in a vibratory meter includes at least a sensor assembly and a meter electronics in communication with the sensor assembly. The system can also include a viscosity meter that is configured to measure the viscosity during, for example, calibration of a vibratory meter that includes the sensor assembly and the meter electronics. The system or, more particularly, the meter electronics, can determine a non-viscosity correlation parameter based on sensor signals from the sensor assembly. The meter electronics may also correlate the non-viscosity correlation parameter with a viscosity of the fluid, which may be provided by the viscosity meter, entered into the meter electronics, etc..

A method can correct the measured flow rate using the non-viscosity correlation parameter during, for example, operation of the vibratory meter. More specifically, the method can determine a fluid flow rate and a non-viscosity correlation parameter of the fluid based on sensor signals from a sensor assembly. The method can correct the fluid flow rate based on the non-viscosity correlation parameter, the non-viscosity correlation parameter being correlated with a viscosity value. The viscosity value may be based on other fluids or non-measured fluids, such as calibration fluids that were previously correlated with the non-viscosity correlation parameter.

Accordingly, an unknown fluid may be measured by the vibratory meter, wherein the non-viscosity correlation parameter is determined for the unknown fluid, and then the flow rate corrected for viscosity effects, even though the viscosity is not measured and the viscosity value of the measured fluid is not known. This eliminates the need for entry of viscosity values of the unknown fluid to be measured or a viscosity meter that measures the viscosity of the unknown fluid to be measured and yet still correct the flow rate for the viscosity effects.

<FIG> shows a vibratory meter <NUM> for correcting a measured flow rate for viscosity effects. As shown in <FIG>, the vibratory meter <NUM> comprises a sensor assembly <NUM> and meter electronics <NUM>. The sensor assembly <NUM> responds to mass flow rate and density of a process material. The meter electronics <NUM> is connected to the sensor assembly <NUM> via leads <NUM> to provide density, mass flow rate, and temperature information over path <NUM>, as well as other information.

The sensor assembly <NUM> includes a pair of manifolds <NUM> and <NUM>', flanges <NUM> and <NUM>' having flange necks <NUM> and <NUM>', a pair of parallel conduits <NUM> and <NUM>', drive mechanism <NUM>, resistive temperature detector (RTD) <NUM>, and a pair of pick-off sensors 170r and 170r. Conduits <NUM> and <NUM>' have two essentially straight inlet legs <NUM>, <NUM>' and outlet legs <NUM>, <NUM>', which converge towards each other at conduit mounting blocks <NUM> and <NUM>'. The conduits <NUM>, <NUM>' bend at two symmetrical locations along their length and are essentially parallel throughout their length. Brace bars <NUM> and <NUM>' serve to define the axis W and W' about which each conduit <NUM>, <NUM>' oscillates. The legs <NUM>, <NUM>' and <NUM>, <NUM>' of the conduits <NUM>, <NUM>' are fixedly attached to conduit mounting blocks <NUM> and <NUM>' and these blocks, in turn, are fixedly attached to manifolds <NUM> and <NUM>'. This provides a continuous closed material path through sensor assembly <NUM>.

When flanges <NUM> and <NUM>', having holes <NUM> and <NUM>' are connected, via inlet end <NUM> and outlet end <NUM>' into a process line (not shown) which carries the process material that is being measured, material enters inlet end <NUM> of the meter through an orifice <NUM> in the flange <NUM> and is conducted through the manifold <NUM> to the conduit mounting block <NUM> having a surface <NUM>. Within the manifold <NUM> the material is divided and routed through the conduits <NUM>, <NUM>'. Upon exiting the conduits <NUM>, <NUM>', the process material is recombined in a single stream within the block <NUM>' having a surface <NUM>' and the manifold <NUM>' and is thereafter routed to outlet end <NUM>' connected by the flange <NUM>' having holes <NUM>' to the process line (not shown).

The conduits <NUM>, <NUM>' are selected and appropriately mounted to the conduit mounting blocks <NUM>, <NUM>' so as to have substantially the same mass distribution, moments of inertia and Young's modulus about bending axes W--W and W'--W', respectively. These bending axes go through the brace bars <NUM>, <NUM>'. Inasmuch as the Young's modulus of the conduits change with temperature, and this change affects the calculation of flow and density, RTD <NUM> is mounted to conduit <NUM>' to continuously measure the temperature of the conduit <NUM>'. The temperature of the conduit <NUM>' and hence the voltage appearing across the RTD <NUM> for a given current passing therethrough is governed by the temperature of the material passing through the conduit <NUM>'. The temperature dependent voltage appearing across the RTD <NUM> is used in a well-known method by the meter electronics <NUM> to compensate for the change in elastic modulus of the conduits <NUM>, <NUM>' due to any changes in conduit temperature. The RTD <NUM> is connected to the meter electronics <NUM> by lead <NUM>.

Both of the conduits <NUM>, <NUM>' are driven by drive mechanism <NUM> in opposite directions about their respective bending axes W and W' and at what is termed the first out-of-phase bending mode of the flow meter. This drive mechanism <NUM> may comprise any one of many well-known arrangements, such as a magnet mounted to the conduit <NUM>' and an opposing coil mounted to the conduit <NUM> and through which an alternating current is passed for vibrating both conduits <NUM>, <NUM>'. A suitable drive signal is applied by the meter electronics <NUM>, via lead <NUM>, to the drive mechanism <NUM>.

The meter electronics <NUM> receives the RTD temperature signal on lead <NUM>, and the left and right sensor signals appearing on leads <NUM> carrying the left and right sensor signals <NUM>, 165r, respectively. The meter electronics <NUM> produces the drive signal appearing on lead <NUM> to drive mechanism <NUM> and vibrate conduits <NUM>, <NUM>'. The meter electronics <NUM> processes the left and right sensor signals and the RTD signal to compute the mass flow rate and the density of the material passing through sensor assembly <NUM>. This information, along with other information, is applied by meter electronics <NUM> over path <NUM> as a signal.

To correct for viscosity secondary effects on the flow rate measurement, correlations between viscosity and non-viscosity correlation parameters are determined for various fluids. The non-viscosity correlation parameter is based on the sensor signals. For example, the left and right sensor signals <NUM>, 165r may be used to determine a non-viscosity correlation parameter. In the following, the non-viscosity correlation parameters include a velocity to flow rate ratio and a frequency ratio. In some embodiments, a flow rate correction value is also determined, such as a percentage of a flow rate. This flow rate correction value is also correlated with the viscosity and the non-viscosity correlation parameter. The flow rate correction value can be used to adjust a flow rate of a vibrating flow meter.

<FIG> shows a graph <NUM> illustrating relationships between mass flow rate errors and correlation parameters used to correct for viscosity effects according to an embodiment. The graph <NUM> includes a correlation parameter axis <NUM> and a mass error axis <NUM>. The correlation parameter axis <NUM> is a fluid velocity-to-flow rate ratio. The mass error axis <NUM> is a percentage that can be used to correct a mass flow rate. As shown in <FIG>, the correlation parameter axis <NUM> ranges from <NUM> to <NUM>. The mass error axis <NUM> ranges from -<NUM> to <NUM>. The graph <NUM> shows a plurality of data points <NUM>, <NUM> for different fluids. The data points <NUM>, <NUM> for each of the different fluids are indicated by the differently shaped markers (e.g., triangle, square, cross, double-cross, etc.) and are grouped into a first set of data points <NUM> and a second set of data points <NUM>.

As shown in the first set of data points <NUM> is comprised of two fluids, a fifth fluid and sixth fluid, that has correlation parameter values that are distinguishable from the second set of data points <NUM>. More specifically, the first set of data points <NUM> is comprised of data that includes correlation parameter values that range from about <NUM> to about <NUM> and mass error that ranges from about -<NUM> to about <NUM>. A first curve <NUM> is fit to the first set of data points <NUM>. The first set of data points <NUM> may be water. More specifically, although the first set of data points <NUM> is indicated by the legend to be comprised of a fifth fluid and a sixth fluid, both the fifth fluid and the sixth fluid may be water with measurements taken at different times or have different contaminants that do not significantly affect the viscosity of the water. The second set of data points <NUM> is comprised of four fluids that have similar viscosity properties such that the correlation parameter values range from about <NUM> to about <NUM> and mass error values that range from about -<NUM> to about <NUM>. A second curve <NUM> is fit to the second set of data points <NUM>. The second set of data points <NUM> may be comprised of, for example, oil, gas-oil, a proprietary oil blend, etc..

As can be appreciated, the first and second curve <NUM>, <NUM> can be used to establish a relationship between a correlation parameter, such as a fluid velocity-to-flow rate ratio and a mass error. The fluid velocity-to-flow rate ratio can be determined, for example, from the sensor signals by calculating a flow rate from the phase difference, calculating the velocity of the fluid using the equivalent cross-sectional area of the conduits <NUM>, <NUM>'. The fluid velocity-to-flow rate ratio may be calculated using these two values and correlated with the viscosity of the fluids, and therefore, can be used to correct a measured flow rate for viscosity effects, as is illustrated in the following.

<FIG> shows a graph <NUM> illustrating relationships between mass flow rate errors and pipe Reynolds number used to correct for viscosity effects according to an embodiment. The graph <NUM> includes a pipe Reynolds number axis <NUM> and a mass error axis <NUM>, which is a percentage error of a mass flow rate. The pipe Reynolds number axis <NUM> is a measure of a viscosity of a fluid. As shown in <FIG>, the pipe Reynolds number axis <NUM> ranges from <NUM> to <NUM>,<NUM>,<NUM> on a logarithmic scale and is unit-less, but is related to the viscosity of the fluids. The mass flow percent error axis <NUM> ranges from -<NUM> to <NUM>. The graph <NUM> shows a plurality of uncorrected mass flow rate errors <NUM> (e.g., an error for an uncorrected mass flow rate reading) for different fluids. The uncorrected mass flow rate errors <NUM> for the different fluids are indicated by the differently shaped markers, such as triangle, square, cross, double-cross, etc. Also shown in <FIG> are corrected mass flow rate errors <NUM> (e.g., an error for a corrected mass flow rate reading) which are illustrated as dashes. As can be appreciated, the corrected mass flow rate errors <NUM> have a smaller magnitude than the uncorrected mass flow rate errors <NUM>.

The corrected mass flow rate errors <NUM> may be obtained by correcting mass flow rate measurements using the non-viscosity correlation parameter discussed with reference to <FIG>. For example, the meter electronics <NUM> could determine the fluid velocity-to-flow rate ratio based on the left and right sensor signals <NUM>, 165r and the equivalent cross-sectional area of the conduits <NUM>, <NUM>'. The viscosity of the fluid may be previously correlated with the non-viscosity correlation parameter and stored in the meter electronics <NUM>. The meter electronics <NUM> can then determine the Reynolds number from the non-viscosity correlation parameter. The meter electronics <NUM> can also have mass error values correlated with Reynold number values. A mass error in percentage can be determined from the Reynolds number. The measured flow rate can then be corrected using the mass error percentage value to result in the corrected mass flow rate errors <NUM> shown in <FIG>.

As can be appreciated, non-viscosity correlation parameters other than the fluid velocity-to-flow rate ratio can be employed to correct a measured flow rate. In addition, there are alternative methods and means of correlating the non-viscosity correlation parameters to the viscosity and a flow rate correction value. An example is discussed in the following with reference to <FIG>.

<FIG> shows a graph <NUM> illustrating relationships between mass flow rate errors and viscosity used to correct for viscosity effects according to an embodiment. The graph <NUM> includes a viscosity axis <NUM> and a correlation parameter axis <NUM>. As shown in <FIG>, the viscosity axis <NUM> ranges from <NUM> to <NUM> centipose (cP). The correlation parameter axis <NUM> is a vibrating frequency ratio and ranges from -<NUM> to <NUM>. The vibrating frequency ratio may be an air-to-fluid frequency ratio. That is, a resonance frequency of the conduit filled with a fluid relative to a resonance frequency of the conduit filled with air. The graph <NUM> shows a plurality of data points <NUM> for different fluids.

The viscosities of the different fluids are correlated with the non-viscosity correlation parameter, which is, in the example shown in <FIG>, the vibrating frequency ratio. The vibrating frequency ratio may be determined by, for example, using the vibratory meter <NUM> described in the foregoing with reference to <FIG>. In particular, the conduits <NUM>, <NUM>' may be filled with air and vibrated at a resonance frequency. This resonance frequency may be stored in the meter electronics <NUM> as an air resonance frequency. The conduits <NUM>, <NUM>' may also be filled with a fluid having a viscosity that is different than air and then vibrated to a resonance frequency. This frequency may also be stored as a fluid resonance frequency. The viscosity of the fluid can be stored and correlated with the corresponding vibrating frequency ratio in the meter electronics <NUM>. Other fluids may also be used to determine other vibrating frequency ratios and viscosity values, which may also be stored in the meter electronics <NUM>. As will be described in more detail in the following with reference to <FIG>, the viscosities may also be measured using a system or, alternatively, the viscosities may simply be programmed into the meter electronics <NUM> as a predetermined value that is associated with a corresponding vibrating frequency ratio.

Still referring to <FIG>, the graph <NUM> illustrates correlations between the measured viscosity of each of the fluids and the vibrating frequency ratios. As is shown, the vibrating frequency ratios range from about <NUM> to about <NUM>. The vibrating frequency ratio of about <NUM> is correlated with a viscosity of about <NUM>. As the viscosity increases from slightly over <NUM>, the ratio of conduit frequencies increases from <NUM> to about <NUM>. The increase has a parabolic appearance which indicates that the values can be fitted to a curve, thereby allowing the use of an equation to correlate a continuous range of vibrating frequency ratios to viscosity.

<FIG> shows a graph <NUM> illustrating relationships between correlation parameters and flow rate correction values used to correct for viscosity effects according to an embodiment. The graph <NUM> includes a correlation parameter axis <NUM> and a mass error axis <NUM>. The correlation parameter axis <NUM> is a non-viscosity correlation parameter, which is the vibrating frequency ratio described above with reference to <FIG>. As shown in <FIG>, the correlation parameter axis <NUM> ranges from <NUM> to about <NUM>. The mass error axis <NUM> is a mass flow rate error, in percentage, and ranges from -<NUM> to <NUM>. The graph <NUM> shows a plurality of data points <NUM> for different fluids that relate the mass error to a viscosity value. The data points <NUM> for each of the different fluids are indicated by the differently shaped markers (e.g., triangle, square, cross, double-cross, etc.).

The mass flow rate error percentage ranges from about -<NUM> to about <NUM> for the vibrating frequency ratio of about <NUM> to about <NUM>. In the vibrating frequency range of about <NUM> to about <NUM>, mass flow rate error percentage drops to range of about -<NUM> to -<NUM>. As can be appreciated, the change in mass flow rate error has a parabolic shape with a peak at a vibrating frequency ratio of about <NUM>. Accordingly, a curve may be fitted to the data from <NUM> to about <NUM>. Further to the right of the figure, at a vibrating frequency ratio of about <NUM>, the mass flow rate error percentage reading ranges from about <NUM> to about -<NUM>. This set of mass flow rate error percentage readings may be approximated with a single mass flow rate error value, such as an average of the mass flow rate error percentage values, which may be about -<NUM>.

The viscosity of the fluid can be measured, input, or otherwise provided so as to be correlated with the non-viscosity correlation parameter. For example, a viscosity of a fluid may be input into the meter electronics <NUM> prior to the fluid flow rate being measured. The meter electronics <NUM> can subsequently correlate the input viscosity with the measured flow rate of the fluid. Alternatively, a system that includes a viscometer in communication with, directly or indirectly, the meter electronics <NUM> can be employed to measure the viscosity of the fluid in a vibratory meter, such as the vibratory meter <NUM> shown in <FIG>. Exemplary systems are described below with reference to <FIG>.

<FIG> shows a system <NUM> for correcting a measured flow rate for viscosity effects according to an embodiment. As shown in <FIG>, the system <NUM> includes the vibratory meter <NUM> with the sensor assembly <NUM> and the meter electronics <NUM> described in the foregoing with reference to <FIG>. The system <NUM> also includes a viscometer <NUM> that is coupled to an inlet of the sensor assembly <NUM> and a controller <NUM> that is communicatively coupled to the viscometer <NUM> and the vibratory meter <NUM>. In particular, the controller <NUM> is communicatively coupled to the meter electronics <NUM>.

The vibratory meter <NUM> is configured to determine a flow rate of a fluid in the vibratory meter <NUM>. In particular, the meter electronics <NUM> is configured to receive sensor signals from the sensor assembly <NUM> and determine the flow rate of the fluid. The meter electronics <NUM> is also configured to determine a non-viscosity correlation parameter of the fluid based on the sensor signals. For example, the meter electronics <NUM> may be configured to determine a fluid velocity-to-mass flow rate ratio based on the sensor signals. The meter electronics <NUM> may also be configured to determine a vibrating frequency ratio.

The viscometer <NUM> can measure a viscosity of the fluid being provided to the vibratory meter <NUM> and provide the measured viscosity to the controller <NUM>. The controller <NUM> can receive the measured viscosity and provide the measured viscosity to the vibratory meter <NUM> and, more particularly, to the meter electronics <NUM>. Alternatively, the vibratory meter <NUM> and, more particularly, the meter electronics <NUM> can provide the measured flow rate and the determined non-viscosity correlation parameter to the controller <NUM>. Alternatively, a viscometer may be in communication with the vibratory meter <NUM>, as will be discussed in the following with reference to <FIG>.

<FIG> shows a system <NUM> for correcting a measured flow rate for viscosity effects according to an embodiment. As shown in <FIG>, the system <NUM> includes the vibratory meter <NUM> with the sensor assembly <NUM> and the meter electronics <NUM> described in the foregoing with reference to <FIG>. The system <NUM> also includes a viscometer <NUM> that may be the same as or different than the viscometer <NUM> that is part of the system <NUM> shown in <FIG>. As shown in <FIG>, the viscometer <NUM> is in direct communication with the vibratory meter <NUM> rather than a controller. Accordingly, the viscometer <NUM> can measure a viscosity of the fluid that is being provided to the vibratory meter <NUM> and provide the measured viscosity to the vibratory meter <NUM>.

As is indicated by the dashed line connecting the viscometer <NUM> to the meter electronics <NUM>, the viscometer <NUM> may not necessarily be connected with the meter electronics <NUM> to provide the viscosity of the fluid. For example, the viscometer <NUM> can measure the fluid at some other time to measure the viscosity of the fluid. The measured viscosity may be entered into the meter electronics <NUM> at a later time. The vibratory meter <NUM> may also be configured to correlate the measured viscosity with the measured flow rate.

With reference to the systems <NUM> and <NUM>, an actual mass flow rate may also be determined using a method or apparatus that is capable of measuring an actual mass flow rate regardless of viscosity. For example, a total volume flow of the fluid through the vibratory meter <NUM> may be measured by the viscometer <NUM>, <NUM> using volume measuring functions. Although the actual mass flow rate can be measured by the viscometer <NUM>, <NUM>, alternative systems can include a separate method/apparatus to determine the actual mass flow rate. The actual mass flow rate can be used to determine a flow rate correction value for the viscosity of the fluid. For example, the measured fluid flow rate provided by the vibratory meter <NUM> may be compared to the actual mass flow rate to determine a mass flow rate error percentage. This mass flow rate error percentage can be correlated with the measured viscosity provided by the viscometer <NUM>, <NUM> and stored in the meter electronics <NUM>.

Accordingly, the meter electronics <NUM> can have a stored viscosity value that is correlated with a non-viscosity correlation parameter and a flow rate correction value. For example, the viscosity value may be correlated with a fluid velocity-to-mass flow rate ratio value and/or a vibrating frequency ratio value and a mass flow rate error percentage value. These correlations can be employed to correct a measured flow rate value, such as a flow rate value measured during operation as the following discussion with reference to <FIG> illustrates.

<FIG> shows a method <NUM> of correcting a measured flow rate for viscosity effects according to an embodiment. As shown in <FIG>, the method <NUM> begins by receiving sensor signals from a sensor assembly in step <NUM>. In step <NUM>, the non-viscosity correlation parameter of the fluid is determined based on the sensor signals. The non-viscosity correlation parameter and a viscosity of the fluid are correlated in step <NUM>.

The non-viscosity correlation parameter may be, for example, a vibrating frequency ratio of a sensor assembly <NUM> in the vibratory meter <NUM>. Other non-viscosity correlation parameters based on the sensor signals may be determined, such as fluid velocity-to-mass flow rate ratio. In the case of the fluid velocity-to-mass flow rate ratio, the parameters of the sensor assembly <NUM> may be relied on along with the sensor signals to determine the non-viscosity correlation parameter. For example, the fluid velocity may be determined based on the effective cross-sectional area of the conduits <NUM>, <NUM>' in the sensor assembly <NUM>.

The viscosity and non-viscosity correlation parameter of the fluid in the vibratory meter may be measured and correlated during manufacturing, on-site calibration, or the like. With reference to the systems <NUM>, <NUM> shown in <FIG>, the viscosity may be measured by a viscometer <NUM>, <NUM> communicatively coupled to the vibratory meter <NUM>. Alternatively the viscosity of the fluids may be measured separately (e.g., predetermined, or the like) and then manually entered into the vibratory meter <NUM>, provided via the path <NUM>, etc..

As a result, during operation, the meter electronics <NUM> can use the sensor signals <NUM>, 165r to determine, for example, a frequency of the sensor assembly <NUM> and use this frequency to determine a ratio of the determined frequency to a frequency of the sensor assembly <NUM> when the sensor assembly is measuring a reference or characterized fluid with a known viscosity value, such as water, air, or the like. This vibrating frequency ratio may be stored in the meter electronics <NUM> along with a flow rate correction value. Both the vibrating frequency ratio and the flow rate correction value can be correlated with the viscosity of the fluid. These and other correlations can be used to correct a measured flow rate.

<FIG> shows a method <NUM> for correcting a measured flow rate for viscosity effects according to an embodiment. As shown in <FIG>, the method <NUM> determines a fluid flow rate and a non-viscosity correlation parameter of a fluid based on sensor signals from a sensor assembly of a vibratory meter. In step <NUM>, the method <NUM> corrects the fluid flow rate based on the non-viscosity correlation parameter correlated with a viscosity value. Accordingly, the measured flow rate can be corrected for viscosity effects without knowing or measuring the viscosity of the measured fluid.

In step <NUM>, the method <NUM> can determine the fluid flow rate and the non-viscosity correlation parameter of the fluid based on sensor signals provided by, for example, the sensor assembly <NUM> in the vibratory meter <NUM>. In this exemplary embodiment, the meter electronics <NUM> can receive the sensor signals provided by the sensor assembly <NUM> and determine the fluid flow rate and the non-viscosity correlation parameter. The non-viscosity correlation parameter may be, for example, a fluid velocity-to-mass flow rate ratio or a vibrating frequency ratio of the vibratory meter <NUM>.

In step <NUM>, the method <NUM> can correct the fluid flow rate based on the non-viscosity correlation parameter correlated with the viscosity value, for example, using a flow rate correction value that is correlated with the viscosity value. For example, the method <NUM> may use the determined non-viscosity correlation parameter that is correlated with a viscosity value to obtain the flow rate correction value also correlated to the same viscosity. The flow rate correction value can be a flow rate percentage, such as a mass flow rate percentage, but may be any suitable value that is correlated with the viscosity and can be used to correct the measured flow rate for viscosity effects.

The viscosity value may or may not be a viscosity value of the fluid being measured in step <NUM>. For example, the viscosity value may be a viscosity value of one or more other fluids or fluids that are not being measured by the sensor assembly <NUM> in the vibratory meter <NUM>. More specifically, referring to the method <NUM> described above, the viscosity value of method <NUM> may be based on fluids measured during calibration that are not the same as the fluid being measured in step <NUM>. Accordingly, the non-viscosity correlation parameter may be used to correct the mass flow rate for viscosity effects of the fluid being measured even though a viscosity value of the fluid being measured is not known.

The embodiments described above provide a vibratory meter <NUM>, systems <NUM>, <NUM> and methods <NUM>, <NUM> for correcting for viscosity effects. The embodiments provide and improve the technical process of measuring flow rates by taking into account viscosity effects of a fluid without necessarily knowing or measuring the viscosity of the fluid. For example, by measuring and correlating the viscosity of various fluids with the non-viscosity correlation parameter, a relationship, such as an equation, between various viscosity values and the non-viscosity correlation may be established. This and other relationships can be used to correct the measured flow rate for viscosity effects.

The correction of the measured flow rate may be performed using a flow rate correction value that has been correlated with viscosity using the various fluids. For example, a mass flow rate error percentage that is correlated with a viscosity value or the non-viscosity correlation parameter may be employed. Because the non-viscosity correlation parameter is based on the sensor signals from the vibratory meter and is correlated with the viscosity of various fluids, additional equipment is not needed, such as a viscometer, or the like, that measures the viscosity of the fluid to correct a flow rate measurement. The non-viscosity correlation parameter may be determined and correlated with a viscosity value based on two or more fluids that are characterized using a viscometer, or viscosity values that are otherwise known. The viscosity of the fluids may also be correlated with the flow rate correction value.

Accordingly, the technology of flow rate measurements is improved by accounting for viscosity effects of the fluid being measured by the vibratory meter. A specific improvement may be the improved accuracy of the flow rate by correcting a measured flow rate using the flow rate correction value. The specific improvement can also be a consistent accuracy in flow rate measurements over various fluids with a wide variety of viscosity values. In addition, because various fluids have been characterized to provide a relationship, such as an equation or data relationship, between the non-viscosity correlation parameter and a flow rate correction value, the operation of the meter electronics is improved by avoiding signal processing associated with real time signals from other equipment such as a viscometer. The operation of the vibratory meter is also improved by ensuring that the viscosity of the fluid being measured is inherently associated with the flow rate measurement. That is, delay issues associated with two different sensors along a conduit carrying a fluid is avoided.

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the present description.

Claim 1:
A system (<NUM>, <NUM>) for determining a non-viscosity correlation parameter for correcting a measured flow rate for viscosity effects of a fluid in a vibratory meter (<NUM>), the system comprising:
a sensor assembly (<NUM>); and
a meter electronics (<NUM>) communicatively coupled to the sensor assembly (<NUM>), the meter electronics (<NUM>) being configured to:
receive sensor signals from the sensor assembly (<NUM>);
determine a non-viscosity correlation parameter based on the sensor signals the system being characterised by the non-viscosity correlation parameter being comprised of a fluid velocity-to-mass flow rate ratio or a vibrating frequency ratio.