Patent Description:
<CIT> discloses a non-vibrating conduit inertia force flowmeter. <CIT> discloses a mass flow measurement device.

While mass flow meters have been developed for direct mass flow measurement of low pressure fluids, these devices can be unsuitable for use with high pressure fluids. As a result, techniques for indirectly measuring mass flow of high pressure fluids have been developed based upon differential pressure and/or density of the fluid. However, because fluid density can be difficult to measure accurately, the accuracy of these indirect mass flow measurements can also suffer.

In general, systems and methods are provided for measurement of mass flow of fluids.

In one embodiment, a mass flow meter is provided that includes a tubular housing, a flexible plate, an actuator, and at least two sensors. The tubular housing extends along a longitudinal axis and is configured to receive a flow of fluid therethrough. The flexible plate has a length positioned along the longitudinal axis and is at least partially coupled to an interior wall of the tubular housing at opposed longitudinal ends of the flexible plate such that the flexible plate can vibrate in torsion. The actuator is configured to apply an oscillating torque to the flexible plate sufficient to vibrate the flexible plate in torsion. The at least two sensors are each configured to measure oscillations of the flexible plate as a function of time at different locations arising from the applied oscillating torque The actuator is positioned outside the tubular housing on or adjacent to an outer surface of the tubular housing.

In certain embodiments, the mass flow meter can include a computing device in electrical communication with the at least two sensors. The computing device can be configured to determine a mass flow of fluid passing through the tubular housing based upon a phase shift between the oscillations of the flexible plate measured by the at least two sensors.

The tubular housing can have a variety of configurations. In one embodiment, a length of the tubular housing can extend between a housing inlet and a housing outlet and the tubular housing can be substantially straight therebetween.

The flexible plate can also have a variety of configurations. In one embodiment, the flexible plate can be configured to deform elastically when vibrating. In certain aspects, a width of the flexible plate can be approximately equal to an inner diameter of the tubular housing. The flexible plate is at least partially coupled to the tubular housing at opposed longitudinal ends of the flexible plate. In another aspect, the flexible plate can include at least one vane extending radially outward from a hollow shaft. In another aspect, the flexible plate can include four vanes.

In another embodiment, the actuator can be configured to apply the oscillating torque at about a longitudinal center of the flexible plate of the flexible plate.

In another embodiment, the actuator can be configured to apply the oscillating torque to the hollow shaft of the flexible plate.

The at least two sensors can also have a variety of configurations. In one embodiment, the at least two sensors can be configured for measurement of the oscillations at approximately symmetric locations on each side of a longitudinal center of the flexible plate.

Methods for measuring mass flow through a tubular housing are also provided. In one embodiment, a method includes driving, by an actuator, a flexible plate within a tubular housing to vibrate in a torsional mode at a selected frequency, receiving a flow of fluid within the tubular housing, measuring a plurality of oscillations of the vibrating flexible plate as a function of time at two different positions along a length of the flexible plate, and determining a mass flow of the fluid within the tubular housing based upon a phase shift between the oscillations measured at the two different positions, wherein the actuator is positioned outside the tubular housing on or adjacent to an outer surface of the tubular housing.

The flexible plate includes opposed longitudinal ends that are attached to an inner wall of the tubular housing.

In another embodiment, driving the flexible plate can include applying an oscillating torque at about a longitudinal center of the flexible plate. In another embodiment, the selected frequency can be a resonance frequency of the flexible plate.

In other aspects, the oscillations can be measured at approximately symmetric locations on each side a longitudinal center of the flexible plate.

In another embodiment, the flexible plate can deform elastically in vibration.

In another embodiment, the flexible plate can include at least one vane extending radially outward from a hollow shaft and the flexible plate can be driven to vibrate in a torsional mode by applying an oscillating torque to the hollow shaft.

In another embodiment, the flexible plate can include four vanes.

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the systems, devices, and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

Mass flow meters can operate by vibrating a pipe carrying a flowing fluid between an inlet and an outlet. The vibration of the pipe can be described by an oscillation, a variation of a measure of the pipe (e.g., position) about a central value. The mass of the flowing fluid resists the vibration motion and causes the pipe to twist. This twist results in a time lag (phase shift) of oscillations of the pipe between the inlet side and the outlet side and this phase shift is directly affected by the mass passing through the tube. However, high pressure fluids are often transported in thick walled pipes that can be difficult to vibrate with sufficient strength for these types of measurements. Accordingly, a mass flow meter is provided that includes a tubular housing containing a flexible plate that vibrates in a twisting manner (torsion). The vibration of the plate is altered by fluid flow therethrough. By measuring oscillations of the flexible plate at different locations, a phase lag of the plate oscillations can be measured and related to mass flow of a fluid traveling through the tubular housing, regardless of its thickness. Other embodiments are within the scope of the disclosed subject matter.

Embodiments of the disclosure are discussed herein with respect to measurement of mass flow of fluids flowing through pipes. However, a person skilled in the art will appreciate that the disclosed embodiments can be employed to measure mass flow in other structures and/or geometries without limit.

<FIG> illustrates one exemplary embodiment of a fluid channel <NUM> (e.g., a pipe or pipeline) containing a flowing fluid <NUM> and a mass flow meter <NUM> at least partially coupled thereto at respective ends. In certain aspects, the fluid channel <NUM> can be positioned within a surrounding environment S, such as a subsea environment. As discussed in detail below, the mass flow meter <NUM> can include a tubular housing <NUM> and a flexible plate <NUM> configured to vibrate in torsion such that measurement of the movement of the flexible plate <NUM> can be related to mass flow of the fluid <NUM>. Thus, regardless of the geometry of the tubular housing <NUM>, mass flow can be measured directly by the mass flow meter <NUM>.

<FIG> illustrates the mass flow meter <NUM> in more detail. As shown, the tubular housing <NUM> can be in the form of a generally circular cylinder having a length L, a wall thickness T, and an inner radius R defining a cavity <NUM>. The length L of the tubular housing <NUM> and the cavity <NUM> can extend along a longitudinal axis A between a housing inlet 202i and a housing outlet 202o positioned at the opposed terminal ends of the tubular housing <NUM>. In certain aspects, the tubular housing <NUM> can be substantially straight between the housing inlet 202i and the housing outlet 202o.

The tubular housing <NUM> can be any tubular geometry formed by any process and material. In certain aspects, the geometry and/or materials of the tubular housing <NUM> can be approximately the same as that of die fluid channel <NUM>. The tubular housing <NUM> can be formed from any suitable materials including, for example, polymers, ceramics, metals, and metal alloys (e.g., steels, copper and copper alloys, aluminum and aluminum alloys, etc.).

The housing inlet 202i and the housing outlet 202o can also be configured to form a fluid-tight coupling (not shown) with the fluid channel <NUM> or any other fluid conveying systems (e.g., pumps, dispensers, etc.). Examples of fluid-tight couplings can include, but are not limited to, threaded engagements, clamps, welds, and the like. One skilled in the art will appreciate that alternative embodiments of the mass flow meter <NUM> can be integrally formed with the fluid channel <NUM>.

<FIG> also illustrates the flexible plate <NUM> positioned within the cavity <NUM>. The flexible plate <NUM> can extend in the direction of the longitudinal axis A of the tubular housing <NUM> and it can be at least partially coupled to an interior wall of the tubular housing <NUM> (e.g., a wall of the cavity <NUM>) at one or more locations. As an example, a first terminal end 204a of the flexible plate <NUM> can be at least partially coupled to the tubular housing <NUM> at or near the housing inlet 202i and a second terminal end 204b of the flexible plate <NUM> can be at least partially coupled to the tubular housing <NUM> at or near the housing outlet 202o. One skilled in the art will appreciate that the flexible plate can alternatively be mounted to the tubular housing at a single one of the terminal ends of the flexible plate. In further embodiments, more than one flexible plate <NUM> can be positioned within the housing (not shown).

As shown in <FIG>, the flexible plate <NUM> can be in the form of a substantially planar plate. A width W of the flexible plate <NUM> can be approximately equal to an inner diameter (2R) of the tubular housing <NUM> such that any gap between the wall of the cavity <NUM> and the flexible plate <NUM> is small and does not allow a significant amount of the fluid <NUM> to pass between opposite edges of the flexible plate <NUM> (e.g., vertically in <FIG>). Alternatively the flexible plate can adopt a curved shape in an undeformed or unflexed state (not shown).

The mass flow meter <NUM> further includes an actuator <NUM>. As shown in <FIG>, the actuator <NUM> is positioned outside the tubular housing <NUM> on or adjacent to an outer surface of the tubular housing <NUM> and at about a longitudinal center of the flexible plate <NUM>. One skilled in the art will appreciate that alternative embodiments of the flow meter (not shown) can place the actuator at different longitudinal and/or radial positions.

The actuator <NUM> can be configured to apply an oscillating torque to the flexible plate <NUM> to drive the flexible plate to vibrate in a torsional mode at a selected frequency. In certain aspects, the actuator <NUM> can be an electromagnetic actuator and at least a portion of the flexible plate <NUM> can be formed from a magnetic material (e.g., metals, metal alloys, steels, polymers, etc.). As an example, the flexible plate <NUM> can include one or more embedded permanent magnets. The actuator <NUM> can also be in electrical communication with a computing device <NUM>. The computing device <NUM> can control an electrical current to the actuator <NUM> to generate one or more magnetic fields that apply the oscillating torque to the flexible plate <NUM> sufficient to drive the flexible plate <NUM> to vibrate in torsion at the selected frequency. In certain aspects, the frequency of vibration can be a resonance frequency of the flexible plate <NUM>. In other embodiments, the actuator <NUM> can be configured to receive feedback from one or more of the sensors to drive the flexible plate <NUM> at resonance.

The mass flow meter <NUM> can also include a plurality of sensors configured to measure movement of the flexible plate <NUM> as a function of time at positions upstream and downstream of the longitudinal center C with respect to the flow of fluid <NUM>. The movement of the flexible plate <NUM> can be characterized by any parameter of the flexible plate <NUM> that oscillates as a function of time when the flexible plate <NUM> vibrates in torsion. Example parameters can include, but are not limited, linear and/or angular parameters such as position, speed, acceleration, and displacement. In certain embodiments, angle, angular speed, and angular acceleration can be measured. In other aspects, stress and/or strain can be measured. Each of the sensors can include a first sensor portion <NUM> (e.g., 214a, 214b, 214c, 214d) and a plurality of corresponding second sensor portions <NUM> (e.g., 216a, 216b). As an example, first sensor portions <NUM> can be a permanent magnetic material positioned on an outer surface of the flexible plate <NUM> or embedded at least partially within the flexible plate <NUM> that generate magnetic fields. Second sensor portions <NUM> can be magnetic pickup sensors including a pickup coil in electrical communication with the computing device <NUM>. Vibration of the flexible plate <NUM> produces a current within the pickup coil due to variation of the magnetic fields generated by first sensor portions <NUM> at second sensor portions <NUM>. The current output by each second sensor portion <NUM> can be affected by a speed of first sensor portion <NUM> and/or a separation distance from first sensor portion <NUM> inducing the current within its pickup coil. The computing device <NUM> can maintain a calibration, allowing the current output to be converted to measurements of the oscillating parameter of the flexible plate <NUM> as a function of time at the position of each first sensor portion <NUM>.

The placement of each first sensor portion <NUM> can vary along the length and width of the flexible plate <NUM>. As shown in <FIG>, first sensor portions 214a, 214b can be positioned at opposed lateral edges of the flexible plate <NUM> and upstream of the longitudinal center C. First sensor portions 214c, 214d can be positioned at opposed lateral edges of the flexible plate <NUM> and downstream of the longitudinal center C. In certain aspects, placement of upstream first sensor portions 214a, 214b and downstream first sensor portions 214c, 214d can be approximately symmetric with respect to the longitudinal center C. As an example, first sensor portions 214a, 214b can be positioned approximately equidistant between the actuator <NUM> and the first terminal end 204a of the flexible plate <NUM> and at opposed lateral edges. Similarly, first sensor portions 214c, 214d can be positioned approximately equidistant between the actuator <NUM> and the second terminal end 204b of the flexible plate <NUM>. In this manner, first sensor portions 214a, 214d can be positioned along one common lateral edge of the flexible plate <NUM> and first sensor portions 214b, 214c can be positioned along another common lateral edge of the flexible plate <NUM>.

<FIG> illustrates the mass flow meter <NUM> with the flexible plate <NUM> in torsion due to an applied torque, with reference to orthogonal axes x, y, z. As shown, die longitudinal axis A is parallel to the x-axis. The actuator <NUM> can apply the torque by exerting forces FA of opposite sign parallel to the y-axis and along the width of the flexible plate (e.g., on opposed lateral edges of the flexible plate <NUM>). By varying the magnitude and sign of the applied force FA, the torque oscillates and drives the flexible plate <NUM> o vibrate in a torsional mode. This torsional vibration can cause the flexible plate <NUM> to rotate about the x-axis with an angular velocity Ωx parallel to the x-axis, and to rotate about the y-axis with an angular velocity Ωy parallel to the y-axis. For example, examining a longitudinal location X approximately equidistant between the housing inlet 202i and the longitudinal center C, the angular velocity in a first longitudinal half <NUM> of the flexible plate <NUM> points in the negative y-direction (into the page) and the angular velocity in a second longitudinal half <NUM> of the flexible plate <NUM> points in the positive y-direction (out of the page).

The mass flow meter <NUM> can measure mass flow of the fluid <NUM> flowing through the cavity <NUM> by the Coriolis Effect. In brief, the Coriolis Effect refers to an inertial force (also referred to as the Coriolis force) that acts on objects in motion relative to a rotating reference frame. The Coriolis force Fc acts in a direction that is a cross-product of the axis of rotation and the direction of motion of the object. That is, the direction of the Coriolis force is perpendicular to the axis of rotation and the direction of motion of the object.

As shown in <FIG>, there are two reference frames in rotation due to the torque applied to the flexible plate <NUM>, one about the x-axis and one about the y-axis. The object in motion in each rotating reference frame is the fluid <NUM> having a velocity Vx parallel to the x-axis. Accordingly, there cannot be a Coriolis force arising from flow of the fluid <NUM> parallel to the x-axis with regard to the reference frame rotating about the x-axis, since the axis of rotation is the same as the direction of flow of the fluid <NUM>. However, there can be a non-zero Coriolis force for flow of the fluid <NUM> parallel to the x-axis with regard to the reference frame rotating about the y-axis. The cross-product of the axis of rotation (the y-axis) and the direction of motion of the fluid <NUM> (the x-axis) is in the direction of the z-axis. As also shown in <FIG>, at the longitudinal location X, the direction of the Coriolis force is in the negative z-direction in the first longitudinal half <NUM> of the flexible plate <NUM> and in the positive z-direction in the second longitudinal half <NUM> of the flexible plate <NUM>. The magnitude of the Coriolis force can vary with distance from the center of the width of the flexible plate <NUM>.

The Coriolis force can be observed as a phase shift (time shift) in oscillations of the flexible plate <NUM> as a function of time at different locations along the length of die flexible plate <NUM>. As discussed above, the oscillations can be any linear and/or angular parameter of the flexible plate <NUM> that oscillates due to the applied oscillating torque (e.g., position, angle, speed, acceleration, stress, strain, etc.). Thus, by measuring the oscillations of the flexible plate <NUM> as a function of time using the sensors positioned upstream and downstream of the longitudinal center C, the phase shift in the oscillations can be measured.

As discussed in greater detail below, the phase shift can be approximately proportional to the mass flow of the fluid <NUM>. Thus, with calibration of the mass flow meter <NUM> to determine the proportionality constant, the measured phase shift can provide a direct measurement of mass flow of the fluid <NUM>. In certain aspects, the computing device <NUM> can receive the proportionality constant and determine the phase shift from the oscillations measured by the sensors to determine the mass flow of the fluid <NUM>.

In alternative embodiments, the number of sensors can be varied. As shown in <FIG>, the mass flow meter <NUM> includes four first sensor portions 214a, 214b, 214c, 214d and two second sensor portions 216a, 216b. However, in certain embodiments, the mass flow meter can include a single sensor (e.g., a first sensor portion <NUM> and a second sensor portion <NUM>) positioned either upstream or downstream of the longitudinal center C of the flexible plate. In this configuration, the phase shift can be determined between the applied oscillating torque and the oscillation measured by the single sensor.

<FIG> illustrate alternative embodiments of flexible plates <NUM>, <NUM>, that include one or more vanes. The flexible plates <NUM>, <NUM> can be mounted within the mass flow meter <NUM> and include first sensor portions <NUM> as discussed above with respect to flexible plate <NUM>. As shown in <FIG>, the flexible plate <NUM> can include a shaft <NUM> and two vanes 404a, 404b extending radially outward therefrom at about <NUM>° with respect to one another. The flexible plate <NUM> can include a shaft <NUM>' and four vanes 404a', 404b', 404c', 404d' extending radially outward therefrom at about <NUM>° with respect to one another. The vanes can possess approximately equal width. In certain embodiments, the shaft <NUM>, <NUM>' can be hollow. An oscillating torque can be applied to the shaft <NUM>, <NUM>' (e.g., internal to the shaft when hollow) to cause the flexible plates <NUM>, <NUM> to vibrate. One skilled in the art will appreciate that the number of vanes and the angle between the vanes can be varied as necessary. As an example, the number of vanes can vary from a minimum of one to any desired number.

<FIG> illustrate deformation of the flexible plate <NUM> predicted from a finite element analysis (FEA) model simulating vibrational motion. In the model, the flexible plate <NUM> is assumed to be formed from stainless steel having dimensions of <NUM> x <NUM> x <NUM>. As shown in <FIG>, forces FA are applied to the lateral edges of the flexible plate <NUM> at about a longitudinal center to simulate the application of an oscillating torque. In the simulation, the magnitude of FA is <NUM> N and a damping of ς = <NUM> is assumed. The resulting deformed shape <NUM> of the flexible plate <NUM> is shown in <FIG>. <FIG> illustrates application of Coriolis forces Fc to the flexible plate <NUM>. The Coriolis forces are zero along the twist axis (x-axis) of the flexible plate <NUM> and at a maximum at the lateral edges of the flexible plate <NUM> with the most bending. <FIG> illustrates a deformed shape <NUM> resulting from application of the Coriolis forces. A sum of the deformations illustrated in <FIG> and <FIG> represents the deformation of the flexible plate <NUM> under the influence of the driver force and the Coriolis force. The shading of <FIG> and <FIG> represents out-of-plane linear displacement of the deformed shapes <NUM> and <NUM>.

<FIG> illustrates one exemplary embodiment of a simulated phase shift as a function of mass flow. The phase shift can be calculated based upon oscillations along one lateral edge of the simulated flexible plate, approximately equidistant between the longitudinal center of the flexible plate and the opposed terminal ends (e.g., analogous to the location of 214a, 214c). As shown in <FIG>, an approximately linear relationship between the simulated phase and mass flow is observed. This linear relationship is maintained over nearly <NUM>, which can be desirable and easily achieved in practice.

<FIG> is a flow diagram illustrating an exemplary embodiment of a method <NUM> for measuring mass flow. As shown, in operation <NUM>, a flexible plate (e.g., flexible plate <NUM>, <NUM>, <NUM>) can be driven to vibrate in torsion at a selected frequency within a tubular housing (e.g., tubular housing <NUM>). In operation <NUM>, a flow of fluid can be received within the tubular housing. The flow of fluid can be received before or after the flexible plate is driven to vibrate. In operation <NUM>, a plurality of oscillations of the vibrating flexible plate can be measured as a function of time. The plurality of oscillations can be measured at two different locations along the length of the flexible plate (e.g., symmetrical about a longitudinal center of the flexible plate). In operation <NUM>, a mass flow of the fluid within the tubular housing can be determined based upon a phase shift between the oscillations measured at the two different positions. Embodiments of the method <NUM> can perform the illustrated operations in a different order and add or omit operations as necessary.

Exemplary technical effects of the methods, systems, and devices described herein include, by way of non-limiting example, direct measurement of mass flow suitable for high wall thickness pipes and high pressure fluids.

The subject matter described herein can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a machine readable storage device), or embodied in a propagated signal, for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software application, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A program can be stored in a portion of a file that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).

The processes and logic flows can also be performed by, and apparatus of the subject matter described herein can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Information carriers suitable for embodying computer program instructions and data include all forms of nonvolatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto optical disks; and optical disks (e.g., CD and DVD disks).

As used herein, the term ''module'' refers to computing software, firmware, hardware, and/or various combinations thereof.

The subject matter described herein can be implemented in a computing system that includes a back end component (e.g., a data server), a middleware component (e.g., an application server), or a front end component (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back end, middleware, and front end components.

Accordingly, a value modified by a term or terms, such as "about" and "substantially," are not to be limited to the precise value specified.

Claim 1:
A mass flow meter (<NUM>), comprising:
a tubular housing (<NUM>) extending along a longitudinal axis and configured to receive a flow of fluid therethrough;
a flexible plate (<NUM>) having a length positioned along the longitudinal axis and at least partially coupled to an interior wall of the tubular housing (<NUM>) at opposed longitudinal ends of the flexible plate such that the flexible plate can vibrate in torsion;
an actuator (<NUM>) configured to apply an oscillating torque to the flexible plate (<NUM>) sufficient to vibrate the flexible plate (<NUM>) in torsion; and
at least two sensors (<NUM>, <NUM>) each configured to measure a plurality of oscillations of the flexible plate (<NUM>) as a function of time at different locations arising from the applied torque,
characterized in that the actuator (<NUM>) is positioned outside the tubular housing (<NUM>) on or adjacent to an outer surface of the tubular housing (<NUM>).