Patent Description:
Accurate measurements of the properties of fluids delivered through flow systems is important for a variety of applications, such as in bioprocessing systems and oil and gas pipelines. One technique for measuring the properties of fluids is by using the flow rate. This permits measurements to be performed during fluid delivery or flow, which is advantageous for reducing associated operating costs. That is, active flow systems may be operational during measurement. Flow rates may be measured either as volumetric flow rates or mass flow rates. Volumetric flow rates are accurate if the density of the fluid is constant; however, this is not always the case as the density may change significantly with temperature, pressure, or composition. As such, mass flow rates are typically more reliable for measuring fluid flow. One method for measuring mass flow rates is through a Coriolis flow sensor (e.g., a flow meter). In general, a Coriolis flow sensor measures mass flow rates via the Coriolis force that results from the fluid as it moves through an oscillating tube.

Certain conventional Coriolis mass flow rate meters and related techniques are known. See, for example, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Various aspects and embodiments of the present invention are defined by the appended claims.

Various features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:.

Coriolis flow sensors are useful in numerous applications that involve fluid flow, such as bioprocessing systems. In general, a Coriolis flow sensor operates by measuring a phase shift of one or more oscillating flow tubes that results from a Coriolis force caused by the fluid flowing inside of the tube. It is beneficial to provide a Coriolis flow sensor design that increases the effect of the Coriolis force, which in turn results in an increased mass flow sensitivity and sensing amplitude (e.g., high signal to noise ratio). That is, the arrangement and the structural characteristics of the components of the sensor assembly as provided herein may influence the sensitivity of the measurements.

Many approaches to modifying the geometric form of the tubing often result in large tubing loops that have no advantage in zero point stability because external disturbances are also magnified (which in turn decrease sensor accuracy). Additionally, many approaches for Coriolis flow sensors designed for high pressure fluid flow may use more rigid material or increase the wall thickness of the pipes, which results in a lower sensitivity of the Coriolis flow sensors. The relationship between the structure of the flow tube and an operating pressure of the fluid flowing through the flow tube is shown by Barlow's formula: <MAT> with t being wall thickness, P is the relative pressure between the inside and the outside of the flow tube, S being the allowable stress (e.g., suitable operating pressure of the flow tube), and D being outer diameter of the flow tube. As the wall thickness increases, the bending stiffness of the flow tube increases, which reduces down the oscillation amplitude that drives the Coriolis effect, which in turn decreases the sensitivity of the sensor and increases the signal to noise ratio. Further, these configurations also take up additional space in a fluid flow system, and the looped geometric form modifies the fluid flow path, which influence pressure loss, flow velocity, shear rate, trappings, draining, and abrasion.

The present disclosure is directed to a Coriolis flow sensor assembly with improved sensitivity and a low signal to noise ratio. The assembly may include a flow tube (e.g., a disposable flow tube), multiple actuators, and multiple sets of sensors. Each actuator drives an oscillation of the flow tube within a respective plane, and each set of sensors is configured to measure the phase shift resulting from the oscillation and the Coriolis force in a given plane. Measuring oscillations in multiple different planes/dimensions may increase the certainty of measurements.

Turning now to the figures, <FIG> is a diagram illustrating an embodiment of the Coriolis flow sensor system <NUM>. The Coriolis flow sensor system <NUM> includes electronics circuitry <NUM> coupled to one or more actuators <NUM> and one or more sensors <NUM>. The three or more actuators <NUM> and the sensors <NUM> are coupled to the flow tube <NUM>.

The electronics circuitry <NUM> includes drive circuitry <NUM> to trigger the one or more actuator(s) <NUM> to generate oscillations in the flow tube <NUM> of the desired frequency and magnitude. The Coriolis flow sensor system <NUM> further includes sensor circuitry <NUM> to receive the Coriolis response from the flow tube <NUM>. The electronics circuitry <NUM> further includes a processor <NUM> to process the Coriolis response signals received from the sensors <NUM> to generate one or more measurements representative of one or more properties of the fluid. These measurements are displayed via a user interface <NUM>. The electronics circuitry <NUM> also includes a memory <NUM> to store the measurements for further use and communication, to store data useful for the drive circuitry <NUM>, and the sensor circuitry <NUM>.

In operation, a flow of a fluid <NUM> is provided to the flow tube <NUM>. The electronics circuitry <NUM> triggers the three or more actuator(s) <NUM> to generate oscillations in the flow tube <NUM>, which are transferred to the fluid <NUM>. The three or more actuators <NUM> are used to induce oscillations of an appropriate amplitude over a required frequency range in the fluid <NUM>. Due to these oscillations and the flow of the fluid <NUM> through the flow tube <NUM>, the Coriolis response (vibration amplitude and phase) is generated in the fluid and is sensed by the sensors <NUM> through the flow tube <NUM>. The sensed Coriolis response signal from the sensors <NUM> are transmitted to the electronics circuitry <NUM> for further processing to obtain the measurements of the one or more properties of the fluid including fluid flow. The one or more sensors <NUM> are configured to provide signals indicative of a Coriolis response caused by the fluid <NUM> flowing through the flow tube <NUM>. The one or more sensors <NUM> may include, for example, electromagnetic sensors, or optical sensors, and associated components. Further, the sensors <NUM> may include separating sensing components, with a portion of the sensor <NUM> being disposed on the flow tube <NUM> and a portion of the sensor <NUM> being spaced apart from the flow tube <NUM>, and whereby the sensor <NUM> is configured to measure a change in physical distance between the components as a measure of the oscillation of the flow tube <NUM>.

The system <NUM> may be used to assess fluid characteristics in any fluid flow system. As disclosed, the fluid characteristics may be assessed during operation of a variety of manufacturing and/or fluid flow processes. Some applications for the system <NUM> described herein include fabrication of wafers in semi-conductor industry, and medical applications that involve use of organic fluids. Some of these are high purity applications, and use of flow tube <NUM> made of for example polymer, or other chemically inert material is advantageous in such applications. In some other applications, a flow tube <NUM> formed of electrically inert and low thermal conductivity material like glass is advantageous.

It would be appreciated by those skilled in the art that one or more components of the Coriolis flow sensor system may be configured as disposable parts, and that other components may be configured as re-usable resident parts. To that end, in implementations in which certain components are disposable, the disposable components may be separable (e.g., by an operator using appropriate tools or by hand) from the resident parts. For example, at least one of the flow tubes <NUM>, the three or more actuators <NUM>, or the one or more sensors <NUM> may be disposable parts, and other parts are configured as reusable resident parts. It would be appreciated by those skilled in the art that the disposable part(s) may be replaced at very low cost in intervals governed by the specific process needs. In addition, in some implementations, the flow tube <NUM> may be changed, without the need for replacement of the entire Coriolis flow sensor. The disposable-part sub-system allows obtaining high accuracy measurements, reusing of part of the Coriolis flow sensor system <NUM>, provides a flexibility for single-use applications, and achieves cost and material savings.

The flow tube <NUM> may be configured as a conduit with an internal passage that permits fluid flow and may be formed in a shape including, but not limited to single, dual or multi loop configurations, split flow, straight tube, counter- or co-flow configurations. In some implementations, the flow tube <NUM> is made from, for example, a polymer whose influence on the oscillation modes (harmonic frequencies) of the mechanical oscillator is not dominant. In some other examples, the flow tube <NUM> is made of metal. In yet other examples, the flow tube <NUM> is made of glass. The flow tube material, in some examples, is tailored to specific requirements of the bioprocessing application, such as temperature, pressure, and the characteristics of the fluid to be measured (e.g., corrosivity). Further, the flow tube <NUM> may be implemented with wall thickness or material features to promote the variable stiffness along its length as provided herein. The flow tube <NUM> may be arranged to permit in-line fluid flow sensing for a fluid processing system. Accordingly, the flow tube may be in fluid communication with fluid conduits of a larger fluid processing system.

In some embodiments, the flow tube <NUM> may include additional structural features that may stabilize and improve the performance of the flow tube <NUM>. As such, the flow tube <NUM> and any additional structural features may be referred to collectively as the fluid flow assembly <NUM>. For example, the fluid flow assembly <NUM> may include a base or housing configured to accommodate the flow tube <NUM>, the actuators <NUM>, and/or the sensors <NUM>. In addition, in embodiments in which the flow tube <NUM> is disposable, the fluid flow assembly may include coupling points to which ends of the flow tube <NUM> may be attached and that fluidically couple the flow tube <NUM> to the fluid flow system <NUM> to permit in-line fluid flow. Further, while the depicted embodiments are in the context of a straight flow tube <NUM>, the fluid flow assembly <NUM> may also accommodate a bent or looped flow tube <NUM>.

<FIG> shows a flow tube <NUM> coupled to multiple actuators <NUM> and multiple sensors <NUM>. As discussed herein, the flow tube <NUM> provides a flow path <NUM>, or flow axis (e.g., in the direction illustrated by the arrow). In general, the actuators <NUM> drive an oscillation of the flow tube <NUM> in a respective plane <NUM>, and when fluid <NUM> is flowing through the flow tube <NUM> along the flow path <NUM>, a Coriolis effect is observed. The sensors <NUM> detect a phase difference in the oscillation of the flow tube <NUM>, which will be discussed in more detail below.

As illustrated, the flow tube <NUM> includes six actuators 14a, 14b, 14c, 14d, 14e, and 14f. Each actuator <NUM> is disposed on or near the flow tube <NUM>, and drives an oscillation in at least one plane <NUM>. For example, the actuator 14a, in operation, drives an oscillation of the flow tube <NUM> in the plane 32a. It should be understood that oscillation of the flow tube <NUM> by the actuator/s <NUM> may primarily occur along a single plane but may also be detectable in other planes, depending on the nature of the oscillation.

Another actuator 14b is radially offset from the actuator 14a (e.g., approximately <NUM> degrees) and may drive an oscillation in the plane 32b. Further, another actuator 14c is radially offset from the actuator 14b and 14a (e.g., approximately <NUM> and <NUM> degrees, respectively). As such, the actuator 14c may drive an oscillation of the flow tube in a third plane 32c. It should be understood that the fluid flow assembly may include more actuators <NUM> and fewer or more sensors <NUM> than in the illustrated embodiment.

While each actuator <NUM> is positioned relatively in the center of the flow tube <NUM> relative to the flow axis <NUM>, it would be appreciated by one of ordinary skill in the art that position of the actuators <NUM> may depend on the physical properties of the flow tube <NUM> as well as the type of oscillations (e.g., order of the mode). While only one actuator <NUM> is illustrated for each respective plane, in some embodiments, two actuators <NUM> may drive an oscillation in the same plane <NUM>.

As illustrated, the flow tube <NUM> includes six sensors 16a, 16b, 16c, 16d, 16e, and 16f that are disposed on an outer surface <NUM> of the flow tube <NUM>. As shown, sensors 16a and 16b are disposed within the plane 32a (e.g., are coplanar), sensors 16c and 16d are disposed within the plane 32b, and sensors 16e and 16f are disposed within the plane 32c. In general, each sensor <NUM> within a plane <NUM> will sense the Coriolis phase shift that results from the fluid flowing along the flow path <NUM> and oscillation driven by the one or more actuators <NUM>. For example, upon the oscillator 14a driving an oscillation of the flow tube <NUM> along the plane 32a and fluid flowing along the flow path <NUM>, there will be phase shift in the oscillation due to the Coriolis effect. Detection of the oscillation may involve a comparison of the flow tube oscillation between two or more spaced apart sensors <NUM>, which may be referred to as a sensor set <NUM>. The sensor set <NUM> may include sensors that a spaced apart along the length of the flow tube <NUM> (e.g., along the axis <NUM>) and/or that are circumferentially spaced apart.

In general operation, each actuator <NUM> may drive an oscillation of the flow tube <NUM> in any order (e.g., sequentially, in combination, etc.) deemed suitable for obtaining the highest signal to noise ratio. <FIG> is a flow chart illustrating an embodiment of the process <NUM> for operating the Coriolis flow sensor system <NUM>, in accordance with the present disclosure. It is to be understood that the steps discussed herein are merely exemplary and certain steps may be omitted or performed in a different order than the order described below. In some embodiments, the process <NUM> may be stored on the non-volatile memory <NUM> and executed by the processor <NUM> of the electronics circuitry <NUM>, or stored in other suitable memory and executed by other suitable processing circuitry associated with the Coriolis flow sensor system <NUM> or separate, suitable processing circuitry.

As shown in the illustrated embodiment of <FIG> at block <NUM>, the processor <NUM> sends signals (e.g., drive signals) that cause an actuator <NUM> to oscillate the flow tube <NUM> in a manner that is detectable in a first plane <NUM>. For example, the actuator 14a may drive an oscillation of the flow tube <NUM> in the plane 32a. When fluid <NUM> is flowing through the flow tube <NUM>, a Coriolis phase effect occurs that induces a phase shift along the oscillating flow tube <NUM>. Then, at block <NUM>, the processor <NUM> measures a first Coriolis phase shift associated with the oscillation in the first plane <NUM> (e.g., plane 32a). That is, the sensors <NUM> are configured to measure the phase shift in the first plane <NUM> and may measure signals or data that is indicative of a property of the fluid flowing through the flow tube <NUM>. Changes in the Coriolis phase effect over time may indicate changes in the characteristics of the fluid,.

At block <NUM>, the processor <NUM> sends suitable signals that cause an actuator <NUM> to oscillate the flow tube <NUM> in a second plane <NUM>. For example, the actuator 14b may drive an oscillation of the flow tube <NUM> in the plane 32b. When fluid <NUM> is flowing through the flow tube <NUM>, a Coriolis phase effect occurs that induces a phase shift along the oscillating flow tube <NUM>. Then, at block <NUM>, the processor <NUM> measures a first Coriolis phase shift associated with the oscillation in the second plane <NUM> (e.g., plane 32b). That is, the sensors <NUM> that are configured to measure the phase shift in the first plane <NUM>, may measure signals or data that is indicative of a property of the fluid.

At block <NUM>, the processor <NUM> determines a property of the fluid based on the Coriolis phase shifts that resulted from the oscillation in the first and second planes <NUM> (e.g., 32a and 32b). In some embodiments, the processor <NUM> may send suitable signals that cause a third actuator <NUM> (e.g., actuator 14c) to drive an oscillation in a third plane 32c, before reaching block <NUM>. Further, the oscillations in flow tube referred to in blocks <NUM> and <NUM> may be at a respective first and second frequency. Even further, the oscillations may be in the same plane <NUM>, but have different frequencies.

As such, one embodiment of the present disclosure is directed to a Coriolis flow sensor assembly with improved sensitivity and low signal to noise ratio. The assembly may include a flow tube (e.g., a disposable flow tube), multiple actuators, and multiple sets of sensors. Each actuator is configured to drive an oscillation of the flow tube within a plane, and each set of sensors is configured to measure the phase shift resulting from the oscillation and the Coriolis force in a given plane.

In another embodiment, the present disclosure is directed to a flow tube with a flow tube shell that reduce loss of oscillation forces. In an embodiment, a Coriolis flow sensor system includes a flow tube shell that surrounds the flow tube. The flow tube shell includes a pressurized volume or gap in between the flow tube and the flow tube shell that may act as a pressure containment and barrier for the flow tube. That is, the pressurized gap reduces the relative pressure, P, as shown in Barlow's formula discussed herein. Further, the pressurized gap may minimize unwanted oscillations, such as oscillations in directions other than the oscillation in the direction driven by the actuator. Unwanted oscillations interfere with the performance and reduce the SNR of the Coriolis flow sensor. For example, the interference can create a phase shift signal not created by the mass flow that also oscillations and result in large data scatter and hysteresis. The flow tube shell may also reduce many structural modifications that are performed to improve the performance of the Coriolis flow sensor, such as looped configurations that introduce dead, or unused, volume. Further, the present techniques may facilitate thinner walls of the flow tube or permitting less rigidity in the flow tube, which lead to increased sensitivity and SNR.

<FIG> is a diagram illustrating an embodiment of the Coriolis flow sensor system <NUM>. The Coriolis flow sensor system <NUM> includes electronics circuitry <NUM> coupled to three or more actuators <NUM> and one or more sensors <NUM>. The three or more actuators <NUM> and the sensors <NUM> are coupled to the flow tube <NUM>. The flow tube <NUM> is enclosed within a flow tube shell <NUM> that also houses the actuators <NUM> and sensors <NUM> to form a Coriolis flow sensor assembly <NUM>.

In operation, a flow of a fluid <NUM> is provided to the flow tube <NUM>. The electronics circuitry <NUM> triggers the three or more actuator(s) <NUM> to generate oscillations in the flow tube <NUM>, which are transferred to the fluid <NUM>. The oscillations in the flow tube <NUM> are relative to the flow tube shell <NUM>, which essentially remains still. The three or more actuators <NUM> are used to induce oscillations of an appropriate amplitude over a required frequency range in the fluid <NUM>. The flow tube shell <NUM> is pressurized either with liquid or gas, and generally prevents oscillations of the flow tube <NUM> in directions or planes other than an intended direction of the oscillation. That is, certain frequencies of the oscillation modes of the flow tube <NUM> may have partial overlap, and these other frequencies may reduce the amplitude of the intended oscillation. As such, the oscillation induced (e.g., driven) by the actuators <NUM> may partially excite unwanted modes. As discussed in more detail below, the pressurized flow tube shell <NUM> reduces or prevents the unwanted oscillations, which may reduce the SNR of the intended oscillation.

Due to these oscillations and the flow of the fluid <NUM> through the flow tube <NUM>, the Coriolis response (vibration amplitude and phase) is generated in the fluid and is sensed by the sensors <NUM> through the flow tube <NUM>. The sensed Coriolis response signal from the sensors <NUM> are transmitted to the electronics circuitry <NUM> for further processing to obtain the measurements of the one or more properties of the fluid including fluid flow. The one or more sensors <NUM> are configured to provide signals indicative of a Coriolis response caused by the fluid <NUM> flowing through the flow tube <NUM>. The one or more sensors <NUM> may include, for example, electromagnetic sensors, or optical sensors, and associated components.

It would be appreciated by those skilled in the art that one or more components of the sensor assembly <NUM> may be configured as disposable parts, and that other components may be configured as re-usable resident parts. To that end, in implementations in which certain components are disposable, the disposable components may be separable (e.g., by an operator using appropriate tools or by hand) from the resident parts. For example, at least one of the flow tubes <NUM>, the three or more actuators <NUM>, or the one or more sensors <NUM> may be disposable parts, and other parts are configured as reusable resident parts. It would be appreciated by those skilled in the art that the disposable part(s) may be replaced at very low cost in intervals governed by the specific process needs. In addition, in some implementations, the flow tube <NUM> may be changed), without the need for replacement of the entire Coriolis flow sensor. The disposable-part sub-system allows obtaining high accuracy measurements, reusing of part of the Coriolis flow sensor system <NUM>, provides a flexibility for single-use applications, and achieves cost and material savings.

As discussed herein, the flow tube <NUM> may be configured as a conduit with an internal passage that permits fluid flow and may be formed in a shape including, but not limited to single, dual or multi loop configurations, split flow, straight tube, counter- or co-flow configurations. In some implementations, the flow tube <NUM> is made from, for example, a polymer whose influence on the oscillation modes (harmonic frequencies) of the mechanical oscillator is not dominant. In some other examples, the flow tube <NUM> is made of metal. In yet other examples, the flow tube <NUM> is made of glass. The flow tube material, in some examples, is tailored to specific requirements of the bioprocessing application, such as temperature, pressure, and the characteristics of the fluid to be measured (e.g., corrosivity). Further, the flow tube <NUM> may be implemented with wall thickness or material features to promote the variable stiffness along its length as provided herein. The flow tube <NUM> may be arranged to permit in-line fluid flow sensing for a fluid processing system. Accordingly, the flow tube may be in fluid communication with fluid conduits of a larger fluid processing system.

As discussed above, the flow tube shell <NUM>, shown in <FIG>, generally reduces the effect of unwanted oscillations. <FIG> is a schematic illustration of a vertical axis <NUM> and a lateral axis <NUM> along a flow tube <NUM>. As shown, the oscillation <NUM> occurs in a plane <NUM> spanning the vertical axis <NUM> and the flow axis <NUM>. Unwanted harmonic modes (e.g., structural modes) may occur along the axes <NUM> and <NUM> and contribute to the Coriolis deflection shape that may reduce the amplitude of the oscillation <NUM>. In order to damp or shift the frequency of unwanted harmonic modes of the flow tube <NUM>, additional structural features may be added. Structural features along certain axes (e.g., <NUM> and <NUM>) may provide independent influence on the different vibration modes with a variable cross section that adjusts (e.g., shift the frequency of the harmonic mode up, shift the frequency down, or decrease the amplitude) the unwanted harmonic modes until the effect of the unwanted harmonic modes is negligibly, resulting in increased sensitivity and robustness of the Coriolis flow sensor assembly. The features that alter the unwanted harmonic modes (e.g., modal features) may have various designs, structures, and properties to address different modes.

<FIG> is a partial cutaway view of a Coriolis flow sensor assembly <NUM> that includes flow tube <NUM> (e.g., a primary tube) and a flow tube shell <NUM> (e.g., secondary tube) of the Coriolis flow sensor system <NUM>. The flow tube includes a plurality of sensors <NUM> that are disposed on the outer surface <NUM> of the flow tube and may operate as described herein. As illustrated the flow tube shell <NUM> is coaxial (e.g., about the flow path <NUM> with the flow tube <NUM>. Further, the flow tube shell <NUM> surrounds the flow tube <NUM> such that a gap <NUM> is formed between the flow tube shell <NUM> and the flow tube <NUM>. As discussed herein, the gap <NUM> may be pressurized with a fluid (e.g., a liquid or gas).

As shown, the gap <NUM> generally surrounds a portion <NUM> of the flow tube <NUM> along the flow path <NUM>. In general, portion <NUM> surrounded by the gap <NUM> would have a suitable length (e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, less than <NUM>% of the total length of the tube. ) of a portion <NUM> of the flow tube <NUM> where the flow tube <NUM> may oscillate under operation. In one embodiment, the flow tube shell <NUM> is in contact with (e.g., attached to) the ends <NUM> of the flow tube <NUM> or couples to a coupling joint <NUM> coupling the flow tube <NUM> to the system <NUM>, and connection between the flow tube <NUM> and the flow tube shell <NUM> at the ends <NUM> may maintain the pressure within the gap <NUM>. The flow tube <NUM> may be composed of a more flexible material than the flow tube shell <NUM>. In certain embodiments, the flow tube assembly <NUM> may be separable from the system <NUM> and may be provided as a unitary assembly.

As shown, a transmitter <NUM> is generally aligned on a central axis <NUM> of the flow tube <NUM> and the flow tube shell <NUM>. The transmitter <NUM> sends signals to the actuator <NUM> that drives an oscillation of the flow tube at a frequency, as discussed herein. Additionally, the transmitter <NUM> may receive signals from the sensors <NUM>. Further, the transmitter <NUM> may include circuitry for managing (e.g., sending signals) to the sensor(s) <NUM> and the actuator(s) <NUM>. Further still, the transmitter <NUM> may provide an interface to the user, either through a visual display or on an electronic interface (e.g., RS-<NUM>).

As illustrated in <FIG>, the actuator <NUM> is disposed near the center axis <NUM>, it would be appreciated by one of ordinary skill in the art that the location of the actuator <NUM> may depend on the mode of the oscillation. For example, a suitable position for an actuator <NUM> may be some fraction along the portion <NUM> of the flow tube <NUM>. Further, as discussed herein, the Coriolis flow system <NUM> may include multiple actuators <NUM> that each drive an oscillation at a frequency/location.

<FIG> shows a cross section along the flow path <NUM> of the flow tube <NUM> that is surrounded by the flow tube shell <NUM>, as show in <FIG>. As shown, the outer surface <NUM> of the flow tube <NUM> is in contact with the pressurized gap <NUM>. The distance <NUM> between the outer surface <NUM> of the flow tube <NUM> and flow tube shell <NUM> may be any suitable distance <NUM> that does not restrict the oscillation(s) of the flow tube <NUM>. <FIG> also shows a transition region <NUM> between one end <NUM> of the flow tube <NUM> and flow tube shell <NUM>. The transition region <NUM> may have any suitable shape between the end <NUM> where the flow tube <NUM> is in contact with the flow tube shell <NUM> and the portion <NUM> having the gap <NUM>.

As such, another embodiment of the present disclosure is directed to a Coriolis flow sensor system having a flow tube and a flow tube shell. In general, a pressurized gap between the flow tube and the flow tube shell reduces effects of unwanted oscillations. One or more actuators and one or more sensors may be disposed within the flow tube shell. The sensors may be disposed on the flow tube and the actuators may be disposed radially around the flow tube about the flow path.

As discussed herein, the Coriolis flow sensor system <NUM> may include multiple actuators <NUM> and multiple sensors <NUM>. As such, the multiple actuators <NUM> may drive multiple oscillations. In some embodiments, complex oscillations may be driven at various frequencies. <FIG> shows the oscillation position <NUM> (e.g., oscillation driven in the axes <NUM> and <NUM>, shown in <FIG>, as a function of time) with three different oscillation frequencies <NUM>, <NUM>, and <NUM>. That is, the oscillation of the flow tube <NUM> may be a combination of multiple oscillations.

Claim 1:
A Coriolis flow sensor system (<NUM>) comprising:
a flow tube (<NUM>) configured to provide a flow path through the flow tube;
a plurality of actuators (<NUM>) distributed radially about the flow tube (<NUM>), wherein a first actuator (14a) of the plurality of actuators is configured to drive a first oscillation in a first plane (32a) and a second actuator (14b) of the plurality of actuators is configured to drive a second oscillation in a second plane (32b); and
a plurality of sensor sets (<NUM>) disposed on the flow tube (<NUM>), wherein each sensor set (<NUM>) comprises two or more sensors configured to sense the first oscillation, the second oscillation, or both; and wherein
the flow tube (<NUM>) is at least partially surrounded by a pressurized flow tube shell (<NUM>) that is coaxial with the flow tube (<NUM>), wherein a third actuator (14c) of the plurality of actuators is configured to drive a third oscillation in a third plane (32c), and characterised in that the second actuator (14b) is radially offset from the first actuator (14a) by about <NUM> degrees, and the third actuator (14c) is radially offset from the first actuator (14a) by about <NUM> degrees.