HK1136870B

HK1136870B - Three pickoff sensor flow meter

Info

Publication number: HK1136870B
Application number: HK10100584.0A
Authority: HK
Inventors: Craig B. Mcanally; Mark James Bell; Gregory Treat Lanham
Original assignee: Micro Motion, Inc.
Filing date: 2006-07-28
Publication date: 2013-10-25

Description

Three pick-off sensor flowmeter

Technical Field

The present invention relates to a flow meter, and more particularly, to a three pickoff sensor flow meter.

Background

Generally, vibrating conduit sensors (vibrating conduit sensors), such as coriolis mass flowmeters and vibrating densitometers, operate by detecting motion of a vibrating conduit containing a flow material. By processing measurement signals received from a motion transducer (motionransducer) associated with the pipe, properties associated with the material in the pipe, such as mass flow, density, etc., can be determined. Typically, the vibration modes of a vibrating material filled system are affected by the combined mass, stiffness and damping characteristics of the containing pipe (containing conduit) and the material contained therein.

A typical coriolis mass flowmeter includes one or more conduits that are connected in a pipeline or other transport system and convey material, such as fluid, mud, etc., in the system. Each conduit may be considered to have a set of natural vibration modes including, for example, simple bending, torsional, radiative, and coupled modes. In a typical coriolis mass flow measurement application, a conduit is excited in one or more vibrational modes as material flows through the conduit, and motion of the conduit is measured at a plurality of points spaced along the conduit. Typically, the excitation is provided by an actuator, for example an electromechanical device (such as a voice coil type driver) that perturbs the conduit in a periodic manner. By measuring the time delay or phase difference between the motions at the transducer locations, the mass flow rate can be determined. Two such transducers (or pickoff sensors) are typically employed to measure the vibrational response of the flow conduit or conduits, and are typically located at positions upstream and downstream of the actuator. The two pickoff sensors are connected to the electronics by a cable (e.g., through two pairs of independent wires). The instrument receives signals from the two pickoff sensors and processes the signals to obtain a mass flow rate measurement.

Flow meters are used for mass flow rate measurements of various flow fluids. One area in which coriolis flow meters can potentially be used is in the metering and dispensing (disconnect) of fuels, including alternative fuels. In response to increasing concerns about pollution and in response to increasing concerns about the cost and availability of unleaded gasoline and other traditional fuels, the alternative fuel market continues to expand. In fact, many governments participate by enacting laws that facilitate the use of alternative fuels.

An opportunity to utilize coriolis meters in the alternative fuel market is in refueling vehicles such as cars, buses, and the like. In the prior art, individual vehicles are fueled at filling stations using either conventional gasoline pumps or using Compressed Natural Gas (CNG) dispensers (dispensers) as an alternative fuel. Conventional gasoline fuel dispensers require two separate, independent meters to enable the simultaneous refueling of two vehicles. The dual meter fuel dispenser is capable of providing two metered flow streams. The two flow streams can flow at different flow rates. The two flow streams may be different stream materials (i.e., two different fuels, for example) and may have different densities.

However, in order to make a fuel pump with competitive alternative fuels in this evolving industry, the overall cost and size of the pump must be minimized. Therefore, it is challenging to develop a cost effective fuel meter (fuel meter) that can provide two fuel flow measurements for two independent flow streams simultaneously.

One prior art solution is to install two separate flow meters in such a fuel dispenser. Although this is a viable solution, it has several drawbacks. The two flow meter devices occupy double the space of a single flow meter device in the fuel dispenser. The two flow meter devices double the flow meter cost of the fuel dispenser. The two flow meter devices require double the electrical power. Two flow meter devices require double the number of distributor assemblies, such as solenoid valves, regulators, check valves, piping, and the like.

Disclosure of Invention

According to an embodiment of the present invention, a three pickoff sensor flow meter is provided. The three pickoff sensor streamsThe meter comprises a first flow conduit carrying a first flow stream, a second flow conduit independent of the first flow stream, and a common driver configured to vibrate the first and second flow conduits. The three pickoff sensor flow meter also includes three pickoff sensors configured to provide first and second time delay values (Δ t) for the first flow conduit and the second flow conduit₁) And (Δ t)₂)。

According to an embodiment of the present invention, a three pickoff sensor flow meter is provided. The three pickoff sensor flow meter includes meter electronics (meters) configured to receive measurement signals, a first flow conduit carrying a first flow stream, a second flow conduit independent of the first flow stream, and a common driver configured to vibrate the first and second flow conduits. The three pickoff sensor flow meter also includes three pickoff sensors coupled to the meter electronics by four wires.

A three pickoff sensor flow meter is provided according to an embodiment of the invention. The three pickoff sensor flow meter includes a first flow conduit carrying a first flow stream, a second flow conduit independent of the first flow stream, and a common driver configured to vibrate the first and second flow conduits. The three pickoff sensor flow meter further includes a shared pickoff sensor configured to produce a shared vibrational response from vibrations of the first and second flow conduits, a first independent pickoff sensor configured to produce a first independent vibrational response from vibrations of the first flow conduit, and a second independent pickoff sensor configured to produce a second independent vibrational response from vibrations of the second flow conduit.

A method of measuring a three pickoff sensor flow meter is provided according to an embodiment of the invention. The method includes vibrating a first flow conduit carrying a first flow stream and vibrating a second flow conduit. The vibration is performed by a common driver. The method also includes receiving a first vibrational response of the first flow conduit. A first vibrational response is generated from the shared pickoff sensor and from the first independent pickoff sensor. The method also includes receiving a second vibrational response of the second flow conduit. A second vibrational response is generated from the shared pickoff sensor and from a second independent pickoff sensor. The method also includes determining a first flow characteristic from the first vibrational response and the second vibrational response.

A method of calibrating a three pickoff sensor flow meter is provided according to an embodiment of the invention. The method includes zeroing (zero out) the three pickoff sensor flow meter and zeroing (reference meter) one or more reference meters in communication with the three pickoff sensor flow meter. The method also includes measuring a first flow through a first flow conduit of the three pickoff sensor flow meter with the three pickoff sensor flow meters and with the one or more reference meters. The method also includes measuring a second flow through a second flow conduit of the three pickoff sensor flow meter with the three pickoff sensor flow meters and with the one or more reference meters. The method also includes determining two Flow Calibration Factors (FCFs) for the three pickoff sensor flow meter using the first flow measurement and the second flow measurement.

Aspects of the invention

In one aspect of the flow meter, the first flow conduit and the second flow conduit originate from a common inlet.

In another aspect of the flow meter, the first flow conduit originates from a first inlet and the second flow conduit originates from a second inlet.

In yet another aspect of the flow meter, the flow meter comprises a coriolis flow meter.

In yet another aspect of the flow meter, the flow meter comprises a vibrating densitometer.

In yet another aspect of the flow meter, the flow meter further comprises meter electronics, wherein the three pickoff sensors are coupled to the meter electronics by four or more wires.

In yet another aspect of the flow meter, the three pickoff sensors comprise: a shared pickoff sensor configured to generate a shared vibrational response from vibrations of both the first flow conduit and the second flow conduit; a first independent pickoff sensor configured to generate a first independent vibrational response in response to vibration of the first flow conduit; and a second independent pickoff sensor configured to generate a second independent vibrational response in response to vibration of the second flow conduit.

In yet another aspect of the flow meter, the three pickoff sensor flow meter is configured to vibrate the first flow conduit carrying the first flow stream and vibrate the second flow conduit, wherein the vibrating is performed by the common driver; receiving a first vibrational response of the first flow conduit, wherein the first vibrational response is generated from a shared pickoff sensor and from a first independent pickoff sensor; receiving a second vibrational response of the second flow conduit, wherein the second vibrational response is generated from the shared pickoff sensor and from a second independent pickoff sensor; and determining a first flow characteristic from the first vibrational response and the second vibrational response.

In yet another aspect of the flow meter, the flow meter further comprises meter electronics, wherein the three pickoff sensors are configured to provide first and second time delay values (Δ t) for the first flow conduit and the second flow conduit₁) And (Δ t)₂)。

In one aspect of the measurement method, the second flow conduit has zero flow.

In another aspect of the measurement method, the second flow conduit carries a second flow stream.

In yet another aspect of the measurement method, the first flow conduit and the second flow conduit originate from a common input.

In yet another aspect of the measurement method, the first flow conduit is derived from a first input and the second flow conduit is derived from a second input.

In yet another aspect of the measurement method, the second flow conduit carries a second flow stream independent of the first flow stream, and the method further comprises determining a second flow stream characteristic from the first vibrational response and the second vibrational response.

In yet another aspect of the measurement method, the determining further includes determining a first mass flow rate of the first flow stream using the first vibrational response and the second vibrational response in the following equationAnd a second mass flow rate of the second flow stream

And

。

at the measurementIn yet another aspect of the method, the determining further comprises determining a first mass flow rate of the first flow stream using the first vibrational response and the second vibrational response in the following equationAnd a second mass flow rate of the second flow stream

And

。

in yet another aspect of the measurement method, the measurement method further comprises zeroing the three pickoff sensor flow meter for a calibration process; clearing one or more reference meters in communication with the three pickoff sensor flow meter; measuring a first flow through a first flow conduit of the three pickoff sensor flow meters with the three pickoff sensor flow meters and with the one or more reference meters; measuring a second flow through a second flow conduit of the three pickoff sensor flow meter with the three pickoff sensor flow meters and with the one or more reference meters; and determining two Flow Calibration Factors (FCFs) for the three pickoff sensor flow meter using the first flow measurement and the second flow measurement.

In yet another aspect of the measurement method, the determining includes determining two Flow Calibration Factors (FCFs) for the three pickoff sensor flow meter using the following equation:

。

in one aspect of the calibration method, the determining includes determining two Flow Calibration Factors (FCFs) for the multi-flow conduit flow meter using the following equation:

。

in another aspect of the calibration method, the determining includes determining two Flow Calibration Factors (FCFs) for the multi-flow conduit flow meter using the following equation:

drawings

FIG. 1 shows a flow meter including a flow meter assembly and meter electronics;

FIG. 2 illustrates a three pickoff sensor flow meter according to an embodiment of the invention;

FIG. 3 illustrates a three pickoff sensor flow meter according to an embodiment of the invention;

FIG. 4 is a flow chart of a measurement method of a three pickoff sensor flow meter according to an embodiment of the invention;

FIG. 5 illustrates a three pickoff sensor flow meter according to an embodiment of the invention;

FIG. 6 illustrates a three pickoff sensor flow meter in a calibration configuration (setup) in accordance with an embodiment of the present invention;

FIG. 7 is a flow chart of a method of calibrating a three pickoff sensor flow meter according to an embodiment of the invention; and

FIG. 8 illustrates a calibration structure according to an embodiment of the present invention.

Detailed Description

Fig. 1 through 8 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

Fig. 1 shows a flow meter 5 that includes a flow meter assembly 10 and meter electronics 20. Meter electronics 20 is connected to flow meter assembly 10 via leads 100 to provide density, mass flow rate, volume flow rate, total mass flow, temperature and other information through path 26. It will be apparent to those skilled in the art that the present invention can be used with any type of coriolis flow meter regardless of the number of drivers, pickoff sensors, flow conduits, or the mode of operation of the vibration. Further, it should be understood that the flow meter 5 may alternatively comprise a vibrating densitometer.

The flow meter assembly 10 includes a pair of flanges (flanges) 101 and 101 ', manifolds 102 and 102 ', a driver 104, a pickoff sensor 105 and 105 ', and flow conduits 103A and 103B. The driver 104 and pickoff sensors 105 and 105' are connected to the flow conduits 103A and 103B.

Flanges 101 and 101 'are attached to manifolds 102 and 102'. Manifolds 102 and 102' may be attached to opposite ends of spacer 106. Spacers 106 maintain the spacing between manifolds 102 and 102' to prevent undesirable vibrations in flow conduits 103A and 103B. When the flowmeter assembly 10 is inserted into a piping system (not shown) carrying the material being measured, the material enters the flowmeter assembly 10 through the flange 101, passes through the inlet manifold 102, where all of the material is directed into the flow conduits 103A and 103B, then through the flow conduits 103A and 103B and back to the outlet manifold 102 ', where it exits the flowmeter assembly 10 through the flange 101'.

Flow conduits 103A and 103B are selected and appropriately mounted to inlet manifold 102 and outlet manifold 102 ' so as to have substantially the same mass distribution, moment of inertia, and elastic modulus about bending axes W-W and W ' -W ', respectively. The flow conduits extend outwardly from the manifolds in a substantially parallel manner.

The flow conduits 103A and 103B are driven by the driver 104 in opposite directions about their respective bending axes W and W' and in a first out of phase bending mode, known as a flow meter. The driver 104 may comprise one of many well-known devices, such as a magnet mounted to the flow conduit 103A and a counter-acting coil mounted to the flow conduit 103B. An alternating current flows through the counter-acting coil to cause the two conduits to oscillate. Meter electronics 20 applies appropriate drive signals to driver 104 via lead 110.

The meter electronics 20 receives sensor signals on leads 111 and 111', respectively. Meter electronics 20 generates a drive signal on lead 110 that causes driver 104 to oscillate flow conduits 103A and 103B. The meter electronics 20 processes the left and right velocity signals from the pickoff sensors 105 and 105' to calculate the mass flow rate. Path 26 provides input and output means that allow meter electronics 20 to interface with an operator or with other electronic systems. The description of fig. 1 is intended only as an example of the operation of a coriolis flow meter and is not intended to limit the teachings of the present invention.

Fig. 2 illustrates a three pickoff sensor flow meter 200 according to an embodiment of the invention. The three pickoff sensor flow meter 200 includes a first flow conduit 210a and a second flow conduit 210 b. In this embodiment, the first and second flow conduits 210a and 210b originate at a common inlet 212 and have separate first and second outlets 213a and 213 b. The two flow conduits 210a and 210b may include flanges (not shown) at the inlet and outlet ends.

Common drive 216 is located between first flow conduit 210a and second flow conduit 210 b. Common driver 216 is configured to vibrate both first and second flow conduits 210a and 210b simultaneously.

Shared pick-off sensor 218 is located between first flow conduit 210a and second flow conduit 210 b. Shared pickoff sensor 218 is configured to generate a shared vibrational response from vibrations of both first flow conduit 210a and second flow conduit 210 b. The shared pickoff sensors 218 may include upstream pickoff sensors or downstream pickoff sensors.

The first independent pickoff sensor 219a is coupled to the first flow conduit 210a and is configured to generate a first independent vibrational response in accordance with the vibration of the first flow conduit 210 a. Second independent pickoff sensor 219b is coupled to second flow conduit 210b and is configured to generate a second independent vibrational response in accordance with the vibration of second flow conduit 210 b.

The first and second independent pickoff sensors 219a and 219b may be supported by any type of rigid support structure (not shown) by which the first and second independent pickoff sensors 219a and 219b are held in a fixed position and measure the relative motion of the vibrations of the corresponding flow conduits. Each of the independent pickoff sensors 219a and 219b produces a vibrational response for a single flow conduit that is independent of the other flow conduit (and independent of the other flow stream).

The shared pickoff sensor 218 and the first and second independent pickoff sensors 219a and 219b are coupled to the meter electronics 20 via four leads 100 (see also fig. 3 and the discussion that follows). Thus, the meter electronics 20 receives and processes the vibrational response from the shared pickoff sensor 218 and the vibrational response from the first and second independent pickoff sensors 219a and 219b (see FIG. 1).

In one embodiment, meter electronics 20 is configured to vibrate first flow conduit 210a carrying the first flow stream and vibrate second flow conduit 210b, wherein the vibration is performed by common drive 216. It should be understood that the second flow conduit 210b need not carry a flow stream. The meter electronics 20 is further configured to receive a first vibrational response of the first flow conduit 210a, receive a second vibrational response of the second flow conduit 210b, and determine a first flow characteristic from the first vibrational response and the second vibrational response, wherein the first vibrational response is generated from the shared pickoff sensor 218 and from the first independent pickoff sensor 219a, and the second vibrational response is generated from the shared pickoff sensor 218 and from the second independent pickoff sensor 219 b.

The first vibrational response includes a shared vibrational response from the shared pickoff sensor 218 and a first independent vibrational response from the first independent pickoff sensor 219 a. First flow pipe time delay (Δ t)₁) Including a phase difference between the shared vibrational response and the first independent vibrational response.

The second vibrational response comprises a shared vibrational response and a second independent vibrational response from the second independent pickup sensor 219 b. Second flow conduit time delay (Δ t)₂) Including a phase difference between the shared vibrational response and the second independent vibrational response.

The time delay (Δ t) thus reflects the phase difference between the upstream and downstream vibrational responses of the flow conduit. The meter electronics 20 can utilize the first flow conduit time delay (Δ t)₁) And a second flow conduit time delay (Δ t)₂) Various flow characteristics of the three pickoff sensor flow meter 200 are determined.

The meter electronics 20 is capable of producing a first flow measurement related to a first flow stream and is capable of producing a second flow measurement related to a second flow stream. For example, the first flow pipe time delay (Δ t)₁) And a second flow conduit time delay (Δ t)₂) Can be used to determine the first and second mass flow ratesAndthe process can also produce density measurements.

Another flow stream characteristic that can be produced by this process is the viscosity value of each flow stream. If the flow areas (flow areas) of the two flow conduits are different, for example, the three pickoff sensor flow meter 200 can be configured to measure dynamic viscosity and coating (coating). Other flow stream characteristics can likewise result from this process and are within the scope of the description and claims.

The first flow stream is independent of the second flow stream. As a result, the first flow stream is not linked to or affected by the second flow stream, and vice versa. Thereby, the flow through each flow conduit can be measured and controlled independently of the flow through the other conduit.

In one embodiment, the flow rate of the first flow stream may be different from the second flow stream. In one embodiment, the first flow stream may comprise a first flow material and the second flow stream may comprise a second flow material (see fig. 5). The first flow stream may have a first density and the second flow stream may have a second density. For example, the first flow stream may include a first fuel and the second flow stream may include a second fuel. These fuels can flow at different rates. Thus, for example, the meter electronics 20 may utilize the first and second flow measurements to perform two independent fuel metering processes.

In one embodiment, the flow meter 200 comprises a coriolis flow meter. Optionally, the flow meter 200 comprises a vibrating densitometer.

As shown, the flow meter 200 may include two operational flow conduits. Alternatively, the flow meter 200 can include one operational flow conduit for carrying a flow stream and one idle (dummy) flow conduit that does not carry a flow stream. In another alternative, the flow meter 200 can include a flow conduit in combination with a balance bar or balance bar.

In one embodiment, as shown, the first flow stream and the second flow stream may originate from a common inlet 212. Alternatively, the first flow stream may originate from the first inlet 212a and the second flow stream may originate from the second inlet 212 b.

In one embodiment, as shown, flow conduits 210a and 210b comprise substantially U-shaped flow conduits. Alternatively, flow conduits 210a and 210b may comprise substantially straight flow conduits (not shown). However, other shapes may also be utilized and are within the scope of the present description and claims.

In one embodiment, the cross-sectional area of the first flow conduit 210a is the same as the cross-sectional area of the second flow conduit 210 b. Alternatively, they may have different cross-sectional areas.

Fig. 3 illustrates a three pickoff sensor flow meter 200 according to an embodiment of the invention. The figure shows meter electronics 20 connected to pickup sensors 218, 219a and 219b via leads 100. The lead 100 may comprise a portion of a cable connection that connects the flow meter assembly 10 to the meter electronics 20 (see fig. 1).

Lead 100 includes lead 100a, lead 100b, lead 100c, and common lead 100d, where lead 100a is connected to the shared pickoff sensor 218, lead 100b is connected to the first independent pickoff sensor 219a, lead 100c is connected to the second independent pickoff sensor 219b, and common lead 100d is connected to all three pickoff sensors 218, 219a, and 219 b.

Single-ended measurement (single-ended measurement) is performed between lead 100a and lead 100d, between lead 100b and lead 100d, and between lead 100c and lead 100 d. This single ended measurement configuration reduces the number of required pickup wires to four.

The present invention utilizes a phase locked loop of the drive algorithm of the flow meter 200. With the phase-locked loop configuration, the drive algorithm is able to lock the phase between one of the pickup sensors and the drive signal. Conveniently, the shared pickoff sensor 218 can be locked to the drive signal for simplicity. By utilizing this locking feature in the pickoff sensor arrangement, a single pickoff sensor can be locked in phase to the drive signal, and having two independent pickoff sensors allows for two independent vibrational responses. A time delay (Δ t) is measured between the locked pickup sensor and each of the two independent pickup sensors. In addition, the locked pickup sensor may further include a reference feedback signal further used to generate the drive signal.

FIG. 4 is a flow chart 400 of a method of measurement for a three pickoff sensor flow meter according to an embodiment of the invention. The method can be used to measure flow through only the first flow conduit 210a, to measure flow through only the second flow conduit 210b, or to measure flow through both the first and second flow conduits 210a and 210b simultaneously.

In step 401, the first flow conduit and the second flow conduit are vibrated by the common driver 216. The first flow conduit 210a can carry a first flow stream and the second flow conduit 210b can carry a second flow stream.

In step 402, a first vibrational response of the first flow conduit 210a is received. The first vibrational response includes the electrical signal generated by the shared pickoff sensor 218 and the electrical signal generated by the first independent pickoff sensor 219 a. The first flow material flows in the first flow conduit 210 a. The first vibrational response can thus comprise a vibrational response of the flow material in the first flow conduit 210 a.

In step 403, a second vibrational response of the second flow conduit 210b is received. The second vibrational response includes the electrical signal generated by the shared pickoff sensor 218 and the electrical signal generated by the second independent pickoff sensor 219 b. The second vibrational response can thus comprise a vibrational response of the flow material in the second flow conduit 210b, can comprise a no-flow vibrational response, or can comprise a vibrational response of an empty second flow conduit 210 b.

In step 404, a first flow stream characteristic is determined. It should be appreciated that more than one first flow stream characteristic can be determined in this step. A first flow stream characteristic is determined from the first and second vibrational responses. The first flow stream characteristic may include a mass flow rate of the first flow materialFurther, the density of the first flow material can be determined from the first and second vibrational responsesDegree, viscosity, and the like.

In step 405, a second flow stream characteristic is determined. It should be appreciated that more than one flow stream characteristic of the second flow stream can be determined in this step. A second flow characteristic is determined from the first and second vibrational responses. The second flow stream characteristic may include a mass flow rate of the second flow materialFurther, the density, viscosity, etc. of the second flow material can be determined from the first and second vibrational responses.

Although the flow through each flow conduit is independent, the mass flow in one flow conduit is not measured independently of the flow through the other conduit. The flow through one conduit induces (induce) a phase in the other conduit. Due to this coupling, a new mass flow equation is used for the two flow channels of the three pickoff sensor flow meter 200 according to the present invention. The new dual-flow pipe equation is based on the time delay (i.e., Δ t) experienced by flow pipes 210a and 210b₁And Δ t₂)。

In a conventional dual tube coriolis flow meter, the phase between two flow conduits is measured and the phase difference between the inlet side pickoff sensors and the outlet side pickoff sensors of the flow meter is calculated. By employing equation (1), this phase difference is converted into a single time delay (Δ t) and used to determine a quantity of flow (e.g., such as a mass flow rate))。

In this equation, a single measurement of the delay time (Δ t) may be used to measure the flow. The time delay (Δ t) is adjusted by the zero time delay (Δ tz). The zero time delay (Δ tz) includes a calibration factor determined under no-flow conditions.

However, this conventional mass flow rate equation is not sufficient for the two flow conduits of the three pickoff sensor flow meter 200. The reason is that: in the dual flow pipe of the present invention, the flow induces a certain phase in the two flow pipes. This is the case even when there is a flow in only one of the two flow pipes. In conventional flow meters, the phase induced in each conduit is the same since common flow is through both flow conduits. As a result, the induced phase does not appear as a phase difference between the two pipes and is not a factor in the calculation result. Thus, a single time delay may be utilized in the prior art to determine flow rate in a conventional flow meter.

In contrast, in the present invention, the first and second flow streams are independent. As a result, the phase induced by the two flows may differ between the two flow conduits. Therefore, a mass flow rate equation based on a single time delay cannot be employed.

Even though flow may exist in only one of the two flow conduits 210a and 210b, the flow in the three pickoff sensor flow meter 200 may still induce phase in both flow conduits 210a and 210 b. The two induced phases may be different. As a result, two time delay measurements from each flow pipe are required in order to measure flow. Flow measurement (flow measurement) may be for one or two flows. An example of this measurement scheme can be shown using equations (2) and (3) below.

Where subscript 1 represents the first flow conduit 210a and subscript 2 represents the second flow conduit 210 b. The second term (i.e., FCF, for example) in equations (2) and (3) is required due to the fact that the flow through one flow tube induces a phase in the other tube₁₂Item "2"). Equations (2) and (3) can be used in the meter electronics 20 to determine the mass flow rates in the two flow conduits 210a and 210 b.

Hereinafter, for the form (Δ t)_B ^A) The superscript a indicates which stream pipe is transmitting the stream. If a stream is being transmitted through the second stream pipe 210b, the time delay value will be of the form (Δ t)_B ²). The subscript B indicates the flow conduit from which the vibrational response was received. Thus, the value (Δ t)₂ ¹) Is the time delay measured for the second flow conduit, where the flow is through the first flow conduit 210 a. Alternatively, the value (Δ t)₁ ²) Is the time delay measured for the first flow conduit 210a, where the flow is through the second flow conduit 210 b. The superscript 0 indicates no flow condition, where the value (Δ t)₁ ⁰) Represented as a time delay measured for the first flow conduit 210a, which is vibrated by the common drive 220 under zero or no flow conditions.

However, simplified forms of equations (2) and (3) can be used to determine the flow stream characteristics. Equations (2) and (3) do not take advantage of any symmetry. One possible form of symmetry is in the time delay. If the time delay is symmetric, i.e. if:

then equations (2) and (3) become:

the T term represents temperature measurement. Tc₁Term is the temperature, Tm, of the first flow conduit 210a₁The term is the temperature of the first flow fluid. Also Tc₂Term is the temperature, Tm, of the second flow conduit 210b₂The term is the temperature of the second flow fluid. (Delta tz)₁) The value is the zero flow calibration value for the first flow conduit 210a, (Δ tz)₂) The value is the zero flow calibration value for the second flow conduit 210 b. Flow calibration factor FCF₁₁、FCF₁₂、FCF₂₁And FCF₂₂Are calibration coefficients determined by flow testing and subsequently used for flow stream characteristic calibration.

Furthermore, these flow calibration factors may also be symmetric. In this case, the flow calibration factors may also be approximately symmetrical (i.e., FCF)₂₁≈FCF₁₂) Equation (5) and equation (6) are further simplified. The symmetry of these equations affects the calibration process.

The ability to measure two mass flow rates may also make it possible to measure additional process variables beyond just these two mass flow rates. For example, if the cross-sectional flow areas of the two flow conduits are different, the ratio of the two flow rates may be related to the dynamic viscosity. Another potential application is the measurement of coatings on the inner surfaces of these flow conduits. Such a flow conduit coating will cause an unbalanced mass in the system and this unbalanced mass can be detected by the ratio of the amplitudes of the two resulting flow conduit vibrational responses. These are just two examples of what a flow meter can implement to measure two independent flow streams.

Fig. 5 illustrates a three pickoff sensor flow meter 200 according to an embodiment of the invention. In this embodiment, the first flow stream originates from the first inlet 212a and passes through the first flow conduit 210 a. Likewise, a second flow stream originates from the second inlet 212b and passes through the second flow conduit 210 b. Otherwise, the operation of the flow meter 200 of this embodiment is the same as the flow meter of fig. 2.

Fig. 6 illustrates a three pickoff sensor flow meter 200 in a calibration configuration 300 according to an embodiment of the invention. In this embodiment, the flow meter 200 has a common inlet 212, and first and second reference meters 391 and 392 are connected to respective outlets 213a and 213b of the first and second flow conduits 210a and 210 b. The flow through the first and second flow conduits 210a and 210b may be controlled by a downstream valve or other device (not shown) in communication with the two outlets 213a and 213 b.

The calibration procedure for a prior art single flow coriolis flow meter represented by equation (1) is fairly simple. The zero time delay (Δ tz) is determined in the three pickoff sensor flow meter 200 at zero flow conditions and the FCF value is determined by testing at a single flow rate. However, as can be seen from equations (2) and (3), and equations (5) and (6), a similar strategy (zero point measurement (Δ tz) and one flow rate per tube test) does not work for a three pickoff sensor flow meter with two independent flow conduits.

According to various embodiments, measurements obtained from the calibration structure 300 can be used to calibrate the three pickoff sensor flow meter 200. Possible calibration operations are discussed below, for example, in connection with fig. 7. However, other calibration techniques are contemplated and are within the scope of the present description and claims.

The first reference meter 391 measures the first flow stream flowing through the first flow conduit 210a and generatesAnd (6) measuring the values. The second reference meter 392 measures the second flow stream flowing through the second flow conduit 210b and generatesAnd (6) measuring the values. Thus, the flow through each flow conduit and associated reference meter is separate and independent from the flow through the other flow conduit. Further, can obtainOther flow measurements are obtained.

In addition, the calibration structure 300 may include a reference meter 393 for measuring the total mass flow rate into the three pickoff sensor flow meter 200The two inlet embodiments of fig. 5 may include reference meters 391 and 392, but not reference meter 393.

Fig. 7 is a flow chart 700 of a method of calibrating a three pickoff sensor flow meter according to an embodiment of the invention. The basic equations for calibration include:

in step 701, the three pickoff sensor flow meter 200 (i.e., the device under test, see FIG. 6) is cleared. In this step, the two flow conduits 210a and 210b of the flow meter 200 are filled with a flow material, although flow is not allowed through the flow meter 200. The flow conduits 210a and 210b are vibrated under no-flow conditions and one or more flow stream characteristics, such as time delay values for the first and second flow conduits, are determinedAnd

for step 701, the flow is zero (mass flow rate)) And the clear operation is performed, equation (7) becomes:

in step 702, the reference meters 391 and 392 are zeroed (i.e., utilizing a zero flow condition) as described above. It should be understood that this step may be performed before or after step 701.

In step 703, a flow is generated through only the first flow conduit 210 a. During the flow process, the flow meter 200 and the first reference meter 391 measure a first flow stream characteristic in the first flow conduit 210 a. For example, the flow meter 200 can record an upstream-downstream time delay of the first flow conduit 210a as the flow is passing through the first flow conduit 210aDuring flow through the first flow conduit 210a but not through the second flow conduit 210b, the flow meter 200 measures a time delay of the second flow conduit 210bIn addition, the first reference meter 391 measures the mass flow rate of the stream flowing through the first flow conduit 210a (i.e., it produces a REF₁Value).

For step 703, where flow is generated in the first flow conduit 210a, equation (7) becomes:

in step 704, a flow is generated through the second flow conduit 210 b. During this flow, the three pickoff sensor flow meter 200 and the second reference meter 392 measure a second flow characteristic in the second flow conduit 210 b. For example, the flow meter 200 measures the time delay of the second flow conduit 210b while flow is passing through the second flow conduit 210bDuring flow through the second flow conduit 210b but no flow through the first flow conduit 210a, the flow meter 200 measures a time delay of the first flow conduit 210aIn addition, the second reference meter 392 measures the mass flow rate of the flow through the second flow conduit 210b (i.e., it generates a REF₂Value). Alternatively, for the calibration structure 800 shown in fig. 8, valves 394a and 394b can be used to direct flow through the second flow conduit 210 b. Thus, only a single reference gauge 393 is required in the calibration structure 800.

For step 704, where flow is generated in the second flow conduit 210b, equation (7) becomes:

in step 705, the flow stream characteristic measurements obtained above are interpolatedInto a (4 × 4) matrix (see equation (13) below). Solving the inverse matrix to produce a flow calibration factor FCF₁₁、FCF₁₂、FCF₂₁And FCF₂₂. These flow calibration factors are used in subsequent flow characteristic calculations, including normal operation determinations of mass flow rate, density, viscosity, and the like.

There are now 4 equations and 4 unknowns. The known (i.e. measured) quantity is REF₁、REF₂、Δt₁ ¹、Δt₂ ¹、Δt₁ ²、Δt₂ ²、Δt₁ ⁰And Δ t₂ ⁰. It should be mentioned again that each clearing step has:

these unknowns are the flow calibration factor FCF₁₁、FCF₁₂、FCF₂₁And FCF₂₂. These FCFs are values to be determined during calibration.

This can then constitute a 4 x 4 matrix equation:

then, the solution is performed using 4 × 4 matrix inversion:

fig. 8 shows a calibration structure 800 according to an embodiment of the invention. The calibration structure 800 may include first and second valves 394a and 394b and a single reference meter 393. The first and second valves 394a and 394b may be controlled to communicate a first flow stream through the first flow conduit 210a, a second flow stream through the second flow conduit 210b, or a combined flow stream through both flow conduits 210a and 210 b.

Reference meter 393 is shown located after the three pickoff sensor flow meter 200 and after valves 394a and 394 b. However, as shown in phantom, the reference meter 393 (and/or valves 394a and 394b) may be located upstream of the flow meter 200.

It should be appreciated that for calibration structure 800, the values REF are generated by reference meter 393 at different times₁And REF₂. For example, during a calibration procedure, a first flow stream is generated through the first flow conduit 210a by opening the first valve 394a and closing the second valve 394 b. The reference measurement subsequently generated by reference meter 393 is REF₁The value is obtained. Then, the first valve 394a is closed and the second valve 394b is opened to generate the second flow through the second flow conduit 210 b. The reference measurement subsequently generated by reference meter 393 is REF₂The value is obtained.

Unlike the prior art, the three pickoff sensor flow meter can share one upstream or downstream pickoff sensor. Unlike the prior art, the pickoff sensors of the three pickoff sensor flow meter require only four wires. As a result, the three pickoff sensor flow meter can be connected using the common nine wire cable currently utilized by conventional flow meters. This enables the use of conventional meter wiring techniques, wiring feedthroughs, electrical connections, and electrical enclosures. Thus, utilizing three pickoff sensors instead of four pickoff sensors saves wiring, space, hardware, and assembly time.

In the present invention, these flow stream characteristic measurements are obtained substantially simultaneously for two independent flow streams. Unlike the prior art, a common drive vibrates two flow conduits that carry two independent flow streams. Unlike the prior art, these flow streams can flow at different flow rates. Unlike the prior art, these flow streams can have different densities. Unlike the prior art, these flow conduits can have different cross-sectional areas. Unlike the prior art, the flow meter can share the driver, eliminating at least one driver.

Advantageously, the cost of the flow meter is reduced due to the sharing of these components. Furthermore, the overall size of the flow meter (and the entire metering/dispensing system) can be reduced. In addition, the common driver and shared pickup sensor reduce power consumption and allow for the use of a single, smaller electronic power source.

Claims

1. A three pickoff sensor flow meter (200), comprising:

a first flow conduit (210a) for conveying a first flow stream;

a second flow conduit (210b) carrying a second flow stream independent of the first flow stream;

a common driver (216) configured to vibrate the first flow conduit (210a) and the second flow conduit (210 b); and

three pickoff sensors (218, 219a, 219b) configured to provide the first flow conduit (210a) and the first flow streamFor a first time delay value (Δ t)₁) And providing a second time delay value (Δ t) for the second flow duct (210b) and the second flow stream₂)。

2. The flow meter (200) of claim 1, with the first flow conduit (210a) and the second flow conduit (210b) originating from a common inlet (212).

3. The flow meter (200) of claim 1, wherein the first flow stream originates from a first inlet (212a) and the second flow stream originates from a second inlet (212 b).

4. The flow meter (200) of claim 1, with the flow meter (200) comprising a coriolis flow meter.

5. The flow meter (200) of claim 1, with the flow meter (200) comprising a vibrating densitometer.

6. The flow meter (200) of claim 1, further comprising meter electronics (20), wherein the three pickoff sensors (218, 219a, 219b) are coupled to the meter electronics (20) by four or more wires (100).

7. The flow meter (200) of claim 1, wherein the three pickoff sensors (218, 219a, 219b) comprise:

a shared pickoff sensor (218) configured to generate a shared vibrational response from vibrations of both the first flow conduit (210a) and the second flow conduit (210 b);

a first independent pickoff sensor (219a) configured to generate a first independent vibrational response from vibrations of the first flow conduit (210 a); and

a second independent pickoff sensor (219b) configured to generate a second independent vibrational response in dependence on vibration of the second flow conduit (210 b).

8. The flow meter (200) of claim 1, wherein the three pickoff sensor flow meter (200) is configured to vibrate the first flow conduit (210a) carrying the first flow stream and vibrate the second flow conduit (210b), wherein the vibrating is performed by the common driver (216); receiving a first vibrational response of the first flow conduit (210a), wherein the first vibrational response is generated from a shared pickoff sensor (218) and from a first individual pickoff sensor (219a) of the three pickoff sensors (218, 219a, 219 b); receiving a second vibrational response of the second flow conduit (210b), wherein the second vibrational response is generated from the shared pickoff sensor (218) and from a second individual pickoff sensor (219b) of the three pickoff sensors (218, 219a, 219 b); and determining a first flow characteristic from the first vibrational response and the second vibrational response.

9. A three pickoff sensor flow meter (200), comprising:

meter electronics (20) configured to receive a measurement signal;

a first flow conduit (210a) carrying a first flow stream;

a second flow conduit (210b) independent of the first flow stream;

three pickoff sensors (218, 219a, 219b) coupled to the meter electronics (20) by four wires (100).

10. The flow meter (200) of claim 9, with the first flow conduit (210a) and the second flow conduit (210b) originating from a common inlet (212).

11. The flow meter (200) of claim 9, with the first flow conduit (210a) originating from a first inlet (212a) and the second flow conduit (210b) originating from a second inlet (212 b).

12. The flow meter (200) of claim 9, with the flow meter (200) comprising a coriolis flow meter.

13. The flow meter (200) of claim 9, with the flow meter (200) comprising a vibrating densitometer.

14. The flow meter (200) of claim 9, with the three pickoff sensors (218, 219a, 219b) being configured to provide a first time delay value (Δ t) for the first flow conduit (210a) and the first flow stream₁) And providing a second time delay value (Δ t) for the second flow duct (210b) and the second flow stream₂)。

15. The flow meter (200) of claim 9, with the three pickoff sensors (218, 219a, 219b) comprising:

16. The flow meter (200) of claim 9, wherein the three pickoff sensor flow meter (200) is configured to vibrate the first flow conduit (210a) carrying the first flow stream and vibrate the second flow conduit (210b), wherein the vibrating is performed by the common driver (216); receiving a first vibrational response of the first flow conduit (210a), wherein the first vibrational response is generated from a shared pickoff sensor (218) and from a first independent pickoff sensor (219a) of the three pickoff sensors (218, 219a, 219 b); receiving a second vibrational response of the second flow conduit (210b), wherein the second vibrational response is generated from the shared pickoff sensor (218) and from a second independent pickoff sensor (219b) of the three pickoff sensors (218, 219a, 219 b); and determining a first flow characteristic from the first vibrational response and the second vibrational response.

17. A three pickoff sensor flow meter (200), comprising:

a first flow conduit (210a) carrying a first flow stream;

a common driver (216) configured to vibrate the first flow conduit (210a) and the second flow conduit (210 b);

18. The flow meter (200) of claim 17, with the first flow conduit (210a) and the second flow conduit (210b) originating from a common inlet (212).

19. The flow meter (200) of claim 17, with the first flow conduit (210a) originating from a first inlet (212a) and the second flow conduit (210b) originating from a second inlet (212 b).

20. The flow meter (200) of claim 17, with the flow meter (200) comprising a coriolis flow meter.

21. The flow meter (200) of claim 17, with the flow meter (200) comprising a vibrating densitometer.

22. The flow meter (200) of claim 17, further comprising meter electronics (20), wherein the shared pickoff sensor (218), the first independent pickoff sensor (219a), and the second independent pickoff sensor (219b) are coupled to the meter electronics (20) by four or more wires (100).

23. The flow meter (200) of claim 17, with the three pickoff sensors (218, 219a, 219b) being configured to provide a first time delay value (Δ t) for the first flow conduit (210a) and the first flow stream₁) And providing a second time delay value (Δ t) for the second flow duct (210b) and the second flow stream₂)。

24. The flow meter (200) of claim 17, with the three pickoff sensor flow meter (200) being configured to vibrate the first flow conduit (210a) carrying the first flow stream and vibrate the second flow conduit (210b), with the vibrating being performed by the common driver (216), receiving a first vibrational response of the first flow conduit (210a), with the first vibrational response being generated from a shared pickoff sensor (218) and from a first independent pickoff sensor (219 a); receiving a second vibrational response of the second flow conduit (210b), wherein the second vibrational response is generated from the shared pickoff sensor (218) and from the second independent pickoff sensor (219 b); and determining a first flow characteristic from the first vibrational response and the second vibrational response.

25. A method of measurement of a three pickoff sensor flow meter comprising:

vibrating a first flow conduit carrying a first flow stream and vibrating a second flow conduit carrying a second flow stream independent of the first flow stream, wherein the vibrating is performed by a common driver;

receiving a first vibrational response of the first flow conduit, wherein the first vibrational response is generated from the shared pickoff sensor and from the first independent pickoff sensor;

receiving a second vibrational response of the second flow conduit, wherein a second vibrational response is generated from the shared pickoff sensor and from a second independent pickoff sensor; and

a first flow characteristic is determined from the first vibrational response and the second vibrational response.

26. The measurement method of claim 25, wherein the second flow conduit has zero flow.

27. The measurement method of claim 25, wherein the first flow conduit and the second flow conduit originate from a common input.

28. The measurement method of claim 25, wherein the first flow conduit is derived from a first input and the second flow conduit is derived from a second input.

29. The method of measuring of claim 25, wherein the method further comprises determining a second flow characteristic from the first vibrational response and the second vibrational response.

30. The measurement method of claim 25, further comprising:

clearing the three pickoff sensor flow meter for a calibration process;

clearing one or more reference meters in communication with the three pickoff sensor flow meter;

measuring a first flow through a first flow conduit of the three pickoff sensor flow meters with the three pickoff sensor flow meters and with the one or more reference meters;

measuring a second flow through a second flow conduit of the three pickoff sensor flow meter with the three pickoff sensor flow meters and with the one or more reference meters; and

two Flow Calibration Factors (FCFs) of the three pickoff sensor flow meter are determined using the first flow measurement and the second flow measurement.

31. A method of calibrating a three pickoff sensor flow meter, the method comprising:

clearing the flow meter of the three pick-up sensors;

measuring a second flow through a second flow conduit of the three pickoff sensor flow meter with the three pickoff sensor flow meters and with the one or more reference meters, wherein the second flow conduit conveys a second flow stream independent of the first flow stream; and