HK1237409B - Differential flowmeter tool - Google Patents

Description

Differential Flow Meter Tools

Technical Field

The present invention relates to flow meters, and more particularly to a tool for determining optimal operating parameters for a differential flow meter system.

Background Art

Vibration sensors, such as vibrating densitometers and Coriolis flowmeters, are well known and are used to measure mass flow and other information about a material flowing through a conduit in a flowmeter. Exemplary Coriolis flowmeters are disclosed in U.S. Patents 4,109,524, 4,491,025, and Re 31,450, all to J.E. Smith et al. These flowmeters have one or more conduits in straight or curved configurations. For example, each conduit in a Coriolis mass flowmeter is configured with a set of natural vibration modes, which may be simple bends, torsional, or coupled. Each conduit can be driven to oscillate in a preferred mode.

Some types of mass flow meters, particularly Coriolis flow meters, can operate in a manner that performs a direct measurement of density, providing volume information via the quotient of mass over density. See, for example, U.S. Patent No. 4,872,351 to Ruesch for a net oil computer that uses a Coriolis flow meter to measure the density of an unknown multiphase fluid. U.S. Patent No. 5,687,100 to Buttler et al. teaches a Coriolis effect densitometer that corrects density readings for mass flow rate effects in a mass flow meter operating as a vibrating tube densitometer.

Material flows into the flow meter from a connected line on the inlet side of the flow meter, is directed through the conduit(s), and exits the flow meter through the outlet side of the flow meter. The natural vibration modes of the vibrating system are defined in part by the combined mass of the conduits and the material flowing within the conduits.

When there is no flow through the flowmeter, the driving force applied to the conduit(s) causes all points along the conduit(s) to oscillate with the same phase or a small "zero offset" (which is the time delay measured at zero flow). When material begins to flow through the flowmeter, the Coriolis force causes various points along the conduit(s) to have different phases. For example, the phase at the inlet end of the flowmeter lags the phase at the location of the centralized driver, while the phase at the outlet leads the phase at the location of the centralized driver. Sensing elements on the conduit(s) generate sinusoidal signals representing the motion of the conduit(s). The signal output from the sensing elements is processed to determine the time delay between the sensing elements. The time delay between two or more sensing elements is proportional to the mass flow rate of the material flowing through the conduit(s).

Meter electronics connected to the driver generate a drive signal to operate the driver, and the mass flow rate and other properties of the material are determined from the signal received from the sensor. The driver can include one of many well-known arrangements; however, a magnet and opposing drive coil have been extremely successful in the flow meter industry. An alternating current is passed to the drive coil to cause the conduit(s) to vibrate at the desired conduit amplitude and frequency. It is also known in the art to provide the sensor as a magnet and coil arrangement very similar to the driver arrangement. However, while the driver receives a current to induce motion, the sensor uses the motion provided by the driver to induce a voltage. The magnitude of the time delay measured by the sensor is very small; typically measured in nanoseconds. Therefore, it is necessary to make the converter output very accurate.

In some cases, it's desirable to incorporate multiple flow meters into a single system. In one such multi-meter example, two flow meters can be used in a large engine fuel system. Such systems are commonly found on large marine vessels. For such vessels, proper fuel management is critical for efficient engine system operation. To accurately measure fuel consumption, a flow meter is placed upstream of the engine, and another flow meter is placed downstream. The difference in readings between the two flow meters is used to calculate the mass of fuel consumed.

A flow meter of a given size requires a certain fluid flow range to maintain accuracy. On the other hand, a given system may have a certain range of fluid flow requirements, thus requiring a flow meter that does not unduly constrain the operation of the system. Therefore, the best flow meter for a particular system is one that accurately measures flow and related parameters but does not constrain flow or introduce an unacceptable pressure drop. When two flow meters are in a single system, the flow constraint and accuracy issues are magnified. For example, a pair of flow meters with a 0.1% accuracy error may not simply add up to 0.2% error when placed in series, but may be much larger. Temperature differences and differences in zero stability between two or more flow meters can also contribute to reduced system accuracy.

Therefore, what is needed in the art are methods and related systems for calculating the most appropriate size and type of flow meter in a multi-flow meter system based on a given set of operational constraints. There is a need for methods and related systems for determining the accuracy of a multi-flow meter system. There is a need for methods and related systems for determining a particular flow meter model from a set of candidate flow meters given project requirements. The present invention overcomes these and other problems and achieves an advancement in the art.

Summary of the Invention

According to an embodiment, a method for determining system accuracy is provided. The embodiment includes the following steps: inputting hardware specifications for a supply flow meter into a computing device, and inputting hardware specifications for a return flow meter into the computing device. System parameters are input into the computing device. The system accuracy is calculated using system logic, wherein the system logic receives input based on the hardware specifications for the supply flow meter, the hardware specifications for the return flow meter, and the system parameters. The calculated system accuracy is stored in a computer-readable storage medium, and the calculated system accuracy is output.

According to an embodiment, a system for configuring a metering system is provided. According to the embodiment, the system includes at least two flow meters, and a computing device configured to receive at least one input and generate at least one output, wherein the at least one input includes at least one flow meter hardware specification and at least one system parameter. The system also includes system logic configured, with respect to the computing device, to calculate at least one output, wherein the at least one output includes at least one of system accuracy and temperature-corrected system accuracy.

aspect

According to aspects, a method for determining system accuracy includes the following steps: inputting hardware specifications regarding a supply flow meter into a computing device; inputting hardware specifications regarding a return flow meter into the computing device; inputting system parameters into the computing device; calculating the system accuracy with system logic, wherein the system logic receives input based on the hardware specifications regarding the supply flow meter, the hardware specifications regarding the return flow meter, and the system parameters; storing the calculated system accuracy in a computer-readable storage medium; and outputting the calculated system accuracy.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a base accuracy value.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a zero offset value.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include temperature drift values.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a maximum flow rate value.

Preferably, the system parameters include a zero point calibration temperature value.

Preferably, the system parameters include fluid density.

Preferably, the system parameters include inlet temperature and outlet temperature.

Preferably, the step of calculating the system accuracy using system logic comprises the following steps:

Calculate the supply flow meter uncertainty U _S , where

To supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

Calibrate temperature for zero point;

To supply zero offset of flow meter;

To supply the basic accuracy of the flow meter; and

is the supply flow rate conversion factor;

The calculation returns the flowmeter uncertainty _UR , where:

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

Calibrate temperature for zero point;

Returns the zero offset of the flow meter;

For the basic accuracy of the return flow meter; and

is the return flow rate conversion factor.

Preferably, the step of calculating the system accuracy using the system logic includes the step of calculating the total differential measurement accuracy, wherein.

Preferably, the step of calculating the system accuracy using system logic includes the step of calculating the process temperature corrected system accuracy, wherein , and wherein is a fuel consumption conversion factor.

Preferably, the method for determining system accuracy includes the step of providing a notification if at least one of a system parameter and a hardware specification is incompatible with at least one predetermined rule.

Preferably, the method for determining system accuracy comprises the steps of: generating suggested hardware specifications for a supply flow meter from input system parameters; and generating suggested hardware specifications for a return flow meter from input system parameters.

According to an aspect, a system for configuring a metering system is provided. The system for configuring a metering system includes at least two flow meters. The system also includes a computing device configured to receive at least one input and generate at least one output, wherein the at least one input includes at least one flow meter hardware specification and at least one system parameter. System logic associated with the computing device is configured to calculate the at least one output, wherein the at least one output includes at least one of system accuracy and temperature-corrected system accuracy.

Preferably, the at least one hardware specification includes a base accuracy value.

Preferably, the at least one hardware specification includes a zero offset value.

Preferably, the at least one hardware specification includes a temperature drift value.

Preferably, the at least one hardware specification includes a maximum flow rate value.

Preferably, the at least one system parameter comprises a zero calibration temperature value.

Preferably, the at least one system parameter comprises fluid density.

Preferably, the at least one system parameter comprises an inlet temperature and an outlet temperature.

Preferably, the at least one fuel system accuracy metric comprises system accuracy.

Preferably, system accuracy includes, among others, and wherein:

;

To supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

Calibrate temperature for zero point;

To supply zero offset of flow meter;

To provide basic accuracy of flow meter;

is the supply flow rate conversion factor;

;

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

Calibrate temperature for zero point;

Returns the zero offset of the flow meter;

For the basic accuracy of the return flow meter; and

is the return flow rate conversion factor.

Preferably, the temperature calibration system accuracy includes, among others, and wherein:

To supply zero offset of flow meter;

To provide basic accuracy of flow meter;

is the supply flow rate conversion factor;

Returns the zero offset of the flow meter;

To return the basic accuracy of the flow meter;

is the return flow rate conversion factor; and

is the fuel consumption conversion factor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows a prior art vibration sensor assembly;

FIG2 shows a prior art fuel system;

FIG3 shows a computing device according to an embodiment of the present invention;

FIG4 illustrates a system for configuring a fluid consuming system according to an embodiment of the present invention;

FIG5 shows hardware specifications according to an embodiment of the present invention;

FIG6 shows system parameters according to an embodiment of the present invention; and

7 is a flow chart describing a method for configuring a fluid-consuming system according to an embodiment of the present invention.

DETAILED DESCRIPTION

Figures 1-7 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the present invention. For the purpose of teaching the principles of the invention, some conventional aspects have been simplified or omitted. Those skilled in the art will recognize that variations of these examples fall within the scope of the present invention. Those skilled in the art will recognize that the features described below can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the specific examples described below, but is only limited by the claims and their equivalents.

1 shows an example of a prior art flow meter 5 in the form of a Coriolis flow meter that includes a sensor assembly 10 and one or more meter electronics 20. The one or more meter electronics 20 are connected to the sensor assembly 10 to measure characteristics of the flowing material such as, for example, density, mass flow rate, volume flow rate, total mass flow, temperature, and other information.

Sensor assembly 10 includes a pair of flanges 101 and 101', manifolds 102 and 102', and conduits 103 and 103'. Manifolds 102 and 102' are attached to opposite ends of conduits 103 and 103'. Flanges 101 and 101' of this example are attached to manifolds 102 and 102'. Manifolds 102 and 102' of this example are attached to opposite ends of spacer 106. Spacer 106 maintains spacing between manifolds 102 and 102' in this example to prevent undesirable vibrations in conduits 103 and 103'. Conduits 103 and 103' extend outward from the manifolds in a substantially parallel manner. When sensor assembly 10 is inserted into a piping system (not shown) carrying flowing material, the material enters sensor assembly 10 through flange 101, passes through inlet manifold 102, where the total amount of material is directed into conduits 103 and 103', flows through conduits 103 and 103' and back into outlet manifold 102' where it exits sensor assembly 10 through flange 101'.

Sensor assembly 10 includes a driver 104. Driver 104 is attached to conduits 103 and 103' in a position where driver 104 can vibrate conduits 103, 103' in a drive mode. More specifically, driver 104 includes a first driver component (not shown) attached to conduit 103 and a second driver component (not shown) attached to conduit 103'. Driver 104 can include one of many well-known arrangements, such as a magnet mounted to conduit 103 and an opposing coil mounted to conduit 103'.

In this example, the drive mode is the first out-of-phase bending mode, and conduits 103 and 103' are preferably selected and appropriately mounted to inlet and outlet manifolds 102, 102' to provide a balanced system having approximately the same mass distribution, moment of inertia, and elastic modulus about bending axes W-W and W'-W', respectively. In this example, where the drive mode is the first out-of-phase bending mode, conduits 103 and 103' are driven by driver 104 in opposite directions about their respective bending axes W-W and W'-W'. A drive signal in the form of an alternating current can be provided by one or more meter electronics 20, such as via passage 110, and passed through a coil to induce oscillation in both conduits 103, 103'. Those skilled in the art will recognize that other drive modes may be used within the scope of the present invention.

The illustrated sensor assembly 10 includes a pair of sensors 105, 105' attached to conduits 103, 103'. More specifically, a first sensor (not shown) is located on conduit 103, and a second sensor (not shown) is located on conduit 103'. In the depicted embodiment, the sensors 105, 105' can be electromagnetic detectors, such as sensor magnets and sensor coils, that generate sensor signals representative of the velocity and position of the conduits 103, 103'. For example, the sensors 105, 105' can supply the sensor signals to one or more meter electronics 20 via passages 111, 111'. Those skilled in the art will recognize that the movement of the conduits 103, 103' is proportional to certain characteristics of the flowing material, such as the mass flow rate and density of the material flowing through the conduits 103, 103'.

It should be appreciated that while the sensor assembly 10 described above includes a dual flow conduit flowmeter, it is well within the scope of the present invention to implement a single conduit flowmeter. Furthermore, while the flow conduits 103, 103' are illustrated as including curved flow conduit configurations, the present invention can be implemented using flowmeters including straight flow conduit configurations. It should also be appreciated that the sensitive elements 105, 105' can include strain gauges, optical sensors, laser sensors, or any other sensor type known in the art. Therefore, the particular embodiment of the sensor assembly 10 described above is merely an example and should in no way limit the scope of the present invention.

In the example shown in FIG1 , one or more meter electronics 20 receive sensor signals from the sensors 105 , 105 ′. Path 26 provides input and output devices that allow the one or more meter electronics 20 to interface with an operator. The one or more meter electronics 20 measure characteristics of the flowing material, such as, for example, phase difference, frequency, time delay, density, mass flow rate, volume flow rate, total mass flow, temperature, meter verification, and other information. More specifically, the one or more meter electronics 20 receive one or more signals, for example, from the sensors 105 , 105 ′ and one or more temperature sensors 107 , such as resistance temperature devices (RTDs), and use this information to measure characteristics of the flowing material.

FIG2 shows a prior art fuel system 200. Fuel system 200 is shown as a typical marine fuel system. This is merely an example of a multi-flow meter system and should not be used to limit the claims or the specification. Fuel is stored in main tanks 202 and 204. In one embodiment, heavy fuel oil (HFO) is stored in a first main tank 202, and marine diesel (MDO) is stored in a second main tank 204. Main tanks 202 and 204 are supplied to a day tank 206 via fuel lines 203 and 205, respectively. This is merely an example, and it should be understood that more than two main tanks may be present, or only one main tank may be present. Day tank 206 is typically sized to store a limited amount of fuel for safety and pollution prevention purposes. Day tank 206 prevents excessive fuel from being stored in areas such as a vessel's engine room, thereby minimizing the risk of fire or explosion. If a fire occurs, limited fuel availability helps reduce the severity of fire-related incidents. Additionally, the day tank 206 receives fuel that is given to the engine 208 but is not utilized thereby, so return fuel is sent back to the day tank 206 via the return fuel line 207. It should be appreciated that although the fuel system 200 shows only one fuel outlet 222 and two flow meters 214, 216, in some embodiments, there will be multiple fuel outlets and more than two flow meters.

During operation, fuel is typically recirculated from the day tank 206 to the engine 208 or other fuel-consuming device, with any unconsumed fuel flowing back to the day tank 206 in a closed loop 218. If the day tank 206 becomes low on fuel, fuel from the main tanks 202, 204 is refilled. Pump 210 provides the necessary motion to pump fuel from the day tank 206 to the engine 208 and back. An in-line preheater 212 heats the fuel to the ideal temperature for utilization by the engine 208. For example, the operating temperature of HFO is generally between 120°C and 150°C, while MDO is ideally between approximately 30°C and 50°C. The appropriate temperature for a particular fuel allows the fuel's viscosity to be controlled and maintained within an ideal range. The kinematic viscosity of a fuel is a measure of its fluidity at a certain temperature. Because the viscosity of a fuel decreases with increasing temperature, the viscosity of the fuel at the moment it leaves the engine's fuel injectors (not shown) must be within the range specified by the engine manufacturer to produce an optimal fuel spray pattern. Off-spec viscosity results in substandard combustion, power loss, and potential deposit formation. The preheater 212 allows for optimal viscosity to be achieved when properly set for the particular fuel being used.

To measure flow parameters such as mass flow rate or density, for example, a series flow meter is utilized. A supply-side flow meter 214 is located upstream of engine 208, while a return-side flow meter 216 is located downstream of engine 208. Since engine 208 does not use all of the fuel supplied to the engine in a common fuel rail system (not shown), excess fuel is recirculated through day tank 206 and closed-loop circuit 218. Therefore, a single flow meter would not provide accurate flow measurements (particularly with respect to engine fuel consumption), so both a supply flow meter 214 and a return flow meter 216 are required (upstream and downstream of engine 208, respectively). The difference in flow rates measured by flow meters 214 and 216 is roughly equal to the flow rate of fuel consumed by engine 208. Therefore, the difference in measured flow rates between flow meters 214 and 216 is the primary value of interest in most applications similar to the configuration shown in FIG. It should be noted that the common rail fuel system is used merely as an example and does not limit the scope of the claimed invention. Other fuel systems in which fuel is returned and/or recirculated are contemplated.

When operating a large engine, knowing the inlet and outlet states of the system is crucial for efficiency and performance. Most engine systems, such as the engine system shown in Figure 2, have a fuel conditioning system that is used to prepare the fuel to a specific viscosity, temperature, and consistency before it enters the engine, such as preheater 212. Having the correct fuel state can strongly influence the performance of the engine. The viscometer 213 downstream of the preheater 212 measures the fuel viscosity, and in certain embodiments can communicate with the preheater 212 to adjust the preheater temperature so that the fuel remains within a predetermined viscosity range.

The meter electronics 20 may include an interface, a digitizer, a processing system, internal memory, external memory, and a storage system. The meter electronics 20 may generate a drive signal and supply the drive signal to the driver 104. Furthermore, the meter electronics 20 may receive sensor signals from the flow meters 214, 216, such as sensor/velocity sensor signals, strain signals, optical signals, temperature signals, or any other signals known in the art. In some embodiments, the sensor signals may be received from the sensors 105, 105'. The meter electronics 20 may operate as a density meter or as a mass flow meter, including as a Coriolis flow meter. It should be appreciated that the meter electronics 20 may also operate as some other types of sensor assemblies, and the specific examples provided should not limit the scope of the present invention. The meter electronics 20 may process the sensor signals to obtain flow characteristics of the material flowing through the flow conduits 103, 103'. In some embodiments, the meter electronics 20 may receive temperature signals from, for example, one or more RTD sensors or other temperature sensors 107.

Meter electronics 20 may receive sensor signals from driver 104 or sensing elements 105 , 105 ′ via leads 110 , 111 , 111 ′. Meter electronics 20 may perform any necessary or desired signal conditioning, such as formatting, amplification, buffering, and the like. Alternatively, some or all of the signal conditioning may be performed in the processing system. Furthermore, interface 220 may enable communication between meter electronics 20 and external devices and additional meter electronics 20 . The interface may be any form of electronic, optical, or wireless communication.

In one embodiment, the meter electronics 20 may include a digitizer, wherein the sensor signal comprises an analog sensor signal. The digitizer may sample and digitize the analog sensor signal to produce a digital sensor signal. The digitizer may also perform any required decimation, wherein the digital sensor signal is decimated to reduce the amount of signal processing required and to reduce processing time.

The meter electronics 20 may include a processing system that may perform operations of the meter electronics 20 and process flow measurements from the sensor assembly 10. The processing system may execute one or more processing routines, such as, for example, a zero consumption acquisition routine, a differential zero determination routine, a general operation routine, and a fuel type signal routine, and thereby process the flow measurements to produce one or more flow measurements.

The processing system may include a general-purpose computer, a microprocessor system, a logic circuit, or some other general-purpose or custom processing device. The processing system may be distributed among multiple processing devices. The processing system may include any form of integrated or independent electronic storage medium. The processing system processes the sensor signals to generate, among other things, a drive signal. The drive signal is supplied to the driver 104 to vibrate the associated conduit(s), such as conduits 103, 103' of FIG1 .

It should be understood that the meter electronics 20 may include various other components and functions well known in the art. These additional features are omitted from the description and drawings for the sake of brevity. Therefore, the present invention should not be limited to the specific embodiments shown and discussed.

When a processing system generates various flow characteristics, such as mass flow rate or volume flow rate, errors may be associated with the generated flow rate due to the zero offset of the vibrating flow meter, and more specifically, changes or drift in the zero offset of the vibrating flow meter. The zero offset can drift from the initially calculated value due to a number of factors, including one or more operating conditions, particularly changes in the temperature of the vibrating flow meter. Temperature changes can be attributed to changes in the fluid temperature, the ambient temperature, or both. In fuel system 200, preheater 212 is primarily responsible for the temperature of the fluid experienced by flow meters 214 and 216. During the initial zero offset determination, temperature changes will likely deviate from the sensor's baseline or calibration temperature. According to embodiments, meter electronics 20 can correct for such drift.

As described in detail below, embodiments of the systems and methods for calculating the accuracy of an optimal differential flow meter system according to embodiments of the present invention are particularly suitable for implementation in conjunction with a computing device 300. Figure 3 is a simplified diagram of a computing device 300 for processing information according to an embodiment of the present invention. This figure is merely an example and should not limit the scope of the claims herein. Those skilled in the art will recognize many other variations, modifications, and alternatives. Embodiments according to the present invention may be implemented in a single application such as a browser, or may be implemented as multiple programs in a distributed computing environment (such as a workstation, a personal computer, or a remote terminal in a client server/relationship). Embodiments may also be implemented as stand-alone devices, such as, but not limited to, laptop computers, tablet computing devices, smart phones, dedicated computing hardware, and metering electronics 20.

FIG3 shows a computing device 300 that includes a display device 302, a keyboard 304, and a trackpad 306. Trackpad 306 and keyboard 304 are representative examples of input devices and may be any input device, such as a touch screen, a mouse, a scroll ball, a barcode scanner, a microphone, and the like. Trackpad 306 has adjacent buttons 308 for selecting items on a graphical user interface device (GUI) displayed on display device 302. FIG3 is a representation of one type of system for implementing the present invention. It will be readily apparent to those skilled in the art that many system types and configurations are suitable for use in conjunction with the present invention. In one embodiment, the computing system includes an operating system such as Windows, Mac OS, BSD, UNIX, Linux, Android, iOS, and the like. However, the device can be easily modified to other operating systems and architectures by those skilled in the art without departing from the scope of the present invention.

The computing device may include a housing 310 that houses computer components such as a central processing unit, a coprocessor, a video processor, input/output (I/O) interfaces, network and communication interfaces, disk drives, storage devices, and the like. Storage devices include, but are not limited to, optical drives/media, magnetic drives/media, solid-state memory, volatile memory, network storage, cloud storage, and the like. The I/O interfaces include serial ports, parallel ports, USB ports, IEEE 1394 ports, and the like. The I/O interfaces communicate with peripheral devices such as printers, scanners, modems, local area networks, wide area networks, virtual private networks, external storage and memory, additional computing devices 300, flow meter 5, and the like. Those skilled in the art will recognize other variations, modifications, and alternatives.

The above system components can communicate with each other and control the execution of instructions from the system memory or storage device, as well as the exchange of information between computer subsystems.Other arrangements of subsystems and interconnections can be easily implemented by those skilled in the art.

4 is an overview of an embodiment of a computer-based system 400 for determining optimal operating parameters for a differential flow meter system according to an embodiment. Some embodiments of the system 400 may process input 402 in the form of data including hardware specifications 404 and system parameters 406. The input 402 is processed by system logic 408 to produce output 410, which includes, for example, system accuracy 412 and temperature-corrected system accuracy 414.

System logic 408 processes input 402, but before processing occurs, any number of compatibility rules 407 may exist to constrain the inputs so that appropriate inputs are received and appropriate outputs are generated. When system parameters 406 and hardware specifications 404 are input into the computing device, compatibility rules 407 verify that input 402 is compatible with predetermined rules. This ensures that the hardware selected for a particular fuel system 200 will function appropriately/effectively and does not create any dangerous or inherently inaccurate fuel system configurations. Other rules include constraints on the size of relevant flow meters. For example, in an embodiment, return flow meter 216 may not be larger than supply flow meter 214. In an embodiment, the return flow rate may not be a value greater than the supply flow rate. In an embodiment, in the case of fuel system 200, inlet temperature 604 may not be higher than outlet temperature 606. In an embodiment, fluid density 602 may not exceed the density of the fluid permitted by the selected flow meter. These are merely examples of rules that may be used, and other rules are contemplated within the scope of this specification and claims. In an embodiment, some rules are used to provide flags or warnings to indicate potential but not absolute problems. These rules can simply warn of potential incompatibilities, but will still allow the system 400 to process such input 402.

System logic 408 processes input 402 and, in an embodiment, any associated factors. Associated factors include other data sources in machine-readable form related to the input, which may be generated during or after processing the input, constants, intermediate values, etc. System logic 408 performs a series of steps, algorithms, and/or equations using input 402 and any associated factors. In one embodiment, code resident on a computer-readable storage medium may instruct a processor to receive input 402 and generate output 410. As indicated in FIG4 , the code may instruct the processor to process input 402 through system logic 408 and calculate output 410, such as, for example, system accuracy 412, 414.

FIG5 is a diagram illustrating hardware specifications 404 used as input 402 to system 400. Hardware specifications 404 are factors/variables related to the flow meters used in a particular system. In the example provided, two flow meters are utilized, so hardware specifications 404 include a supply flow meter factor 500 and a return flow meter factor 502. Such factors include model 504, basic accuracy 506 of each meter, zero offset 508 of each meter, temperature drift of each meter 510, and maximum flow rate 512 of each meter. Note that none of these factors need to be the same or different between the supply flow meter 214 and the return flow meter 216. Model 504 is an identifier of a particular flow meter with a particular set of associated properties. For example, and without limitation, a "MicroMotion F025" flow meter is a Coriolis mass flow meter that accepts line sizes from 1/4" to 1/2" and can receive a fluid flow of 100 lb/min. By way of example, other characteristics associated with this particular model are shown in Table 1:

The basic accuracy 506 of the flow meter 214, 216 is the error rate associated with the particular flow meter used in the application. The basic accuracy 506 is typically a given user selection and may range, for example, from an error of approximately 0.05% to 0.5% of the flow rate depending on the particular fluid passing through the meter, the particular flow metric being measured, and the inherent accuracy level in the flow meter.

Zero offset 508, or zero stability, is a metric, preferably measured in lb/min, that indicates the flow recorded by the flow meter when there is zero flow through conduits 103, 103'. Generally, the flow meter 5 is initially calibrated at the factory to generate a zero offset plot. In use, a flow calibration factor is typically multiplied by the time delay measured by the sensor minus the zero offset 508 to generate the mass flow rate. In most cases, the flow meter 5 is initially calibrated and assumed to provide accurate measurements without the need for subsequent calibration. While this initially determined zero offset 508 may adequately correct measurements in many cases, zero offset 508 can vary over time due to changes in various operating conditions, including temperature, resulting in only partial correction. However, other operating conditions can also affect zero offset 508, including pressure, fluid density, sensor installation conditions, etc. Furthermore, zero offset 508 can vary at different rates from one meter to another. This may be of particular interest in situations where more than one meter is connected in series so that each of the meters will read the same value if measuring the same fluid flow. In an embodiment, the zero offset 508 is a fixed value. In another embodiment, multiple zero offsets 508 are stored in memory and the appropriate zero offset 508 is applied to the calculation based on process temperature, temperature difference between flow meters 214, 216, pressure, fluid density, and/or sensor installation conditions.

Temperature drift 510 is the known rate at which the accuracy of a flow meter drifts as it moves away from the temperature at which factory zero calibration occurs. Temperature drift 510 is measured as a percentage of the maximum flow rate 512 for a particular flow meter. Maximum flow rate 512 is simply the maximum flow rate that a particular flow meter can accurately measure.

FIG6 is a diagram illustrating system parameters 406 used as inputs 402 to system 400. System parameters 406 are factors/variables related to the system 400 into which the flow meter will be integrated. In the example provided, two flow meters are utilized: a supply flow meter 214 located upstream of the engine 208, and a return flow meter 216 located downstream of the engine 208. A zero calibration temperature 600 is the temperature at which each flow meter 214, 216 is calibrated by the end user or at the factory. A fluid density 602 is the density of the fluid utilized by the fuel system 200 (preferably measured in g/cc). In one embodiment, simply entering the type of fuel utilized and the process temperature will calculate the fluid density 602 by accessing a lookup table containing relevant fuel data. In one embodiment, a user can manually enter the fluid density 602. An inlet temperature 604 is the known temperature of the fluid immediately prior to entering the supply flow meter 214, while an outlet temperature 606 is the temperature of the fluid immediately prior to entering the return flow meter 216. These temperatures may correspond to, for example, the flow meter temperature or the meter electronics temperature. Finally, conversion factor 608 refers to any factor or constant utilized by an equation or algorithm of system 400. Some examples of conversion factor 608 include, without limitation, constants that convert or modify a measurement value to U.S. customary units and/or vice versa.

The system logic 408 calculates any series of steps, algorithms, and/or equations using the input 402 and any associated factors and executes an executable to generate an output 410, such as system accuracy 412, 414. In an embodiment, the system logic 408 calculates the supply flow meter uncertainty. The supply flow meter uncertainty according to an embodiment is calculated according to equation (1):

(1)

in:

= Supply flow meter uncertainty

= Temperature drift of the supply flow meter

= Maximum supply flow meter flow rate

= Inlet temperature

= Zero calibration temperature

= Zero offset of the supply flow meter

= Basic accuracy of the supply flow meter

= Supply Flow Rate Conversion Factor

As mentioned above, temperature drift 510, maximum supply flow meter flow rate 512, supply flow meter zero offset 508, and supply flow meter basic accuracy 506 are supply flow meter factors 500 input into system 400. Inlet temperature 604 is a system parameter 406 input into system 400. The supply flow rate conversion factor is conversion factor 608.

Similarly, the return flow meter uncertainty is calculated in the system logic 408 according to equation (2) in an embodiment:

(2)

in:

= Returns the flow meter uncertainty

= Temperature drift of the return flow meter

= Maximum return flowmeter flow rate

= outlet temperature

= Zero calibration temperature

= Returns the zero offset of the flow meter

= Returns the basic accuracy of the flow meter

= Returns the flow rate conversion factor

According to an embodiment, system accuracy 412 is calculated in system logic 408 according to equation (3). This embodiment reflects the uncertainty in the total differential measurement that relies on the factory zero point.

(3)

in:

= Total differential measurement accuracy calculated from factory zero

According to an embodiment, the temperature corrected system accuracy 414 is calculated in the system logic 408 according to equation (4). This embodiment reflects the uncertainty in the total differential measurement that relies on zeroing at the process temperature.

(4)

in:

= Total differential measurement accuracy calculated at process temperature

= Supply flow meter zero point stability

= Basic accuracy of the supply flow meter

= Supply Flow Rate Conversion Factor

= Returns the zero offset of the flow meter

= Returns the basic accuracy of the flow meter

= Returns the flow rate conversion factor

= Fuel Consumption Conversion Factor

Equations (3) and (4) serve only as examples for calculating the accuracy of a multi-meter system having two flow meters in series and should not limit the claims or the specification in any way. Alternative equations and algorithms are contemplated. One such alternative example is implemented by equation (5), where the differential meter accuracy is determined by the system logic 408 using a root-sum-square analysis:

(5)

in:

=Accuracy by the square root of the sum

= Flow rate before the engine

= Flow rate after the engine

= Basic accuracy of the supply flow meter

= Returns the basic accuracy of the flow meter

Fig. 7 is a flow chart illustrating an embodiment of a method for configuring a fluid consumption system with at least two flow meters, which are designed to provide differential measurement, such as, for example, fluid consumption. The first step includes inputting data into a computing device 300. Specifically, hardware specifications 404 for the supply flow meter 214 are input into the computing device 300 in step 700. Similarly, hardware specifications 404 for the return flow meter 216 are input into the computing device 300 in step 702. As mentioned above, hardware specifications may include at least such factors, such as model 504, the basic accuracy 506 of each meter, the zero offset 508 of each meter, the temperature drift of each meter 510, and the maximum flow rate 512 of each meter. Other specifications may also be input in steps 700 and 702, and those listed are only used as examples of potential specifications without limitation.

In step 704, system parameters 406 are input into the computing device 300. Such parameters include the zero calibration temperature 600, the fluid density 602, the inlet temperature 604, which is the temperature of the fluid immediately before entering the return flow meter 216, the outlet temperature 606, and any conversion factors 608. Other system parameters 406 may also be input in step 704, and those listed serve only as examples of potential inputs, not limitations. In an embodiment, the computing device 300 calculates and recommends a particular flow meter model or specification based on the system parameter inputs in step 704. In this embodiment, step 704 is performed before steps 700 and 702, and the flow meter hardware specifications 404 are generated and recommended by the computing device. In one embodiment, these recommended hardware specifications 404 are automatically input into the computing device 300.

A large number of rules may exist for the system, stored, for example, in a memory or computer-readable medium. Such rules are used to constrain inputs and outputs so that appropriate inputs are received and appropriate outputs are generated. For example, a fuel system 200 having a maximum mass flow of fluid into the supply flow meter 214 of 200 lb/min will not be compatible with a supply flow meter 214 having a maximum flow rate of only 100 lb/min. Therefore, when the system parameters 406 and hardware specifications 404 are input into the computing device in steps 700, 702, and 704, the next step (step 706) verifies that the input 402 is compatible with the predetermined rules. Therefore, in the above example, the fuel system 200 has a flow that exceeds the capacity of the selected supply flow meter 214, so a notification is generated in step 707. After generating the notification, the system 400 prompts the user to re-enter compatible inputs. These steps 706 and 707 ensure that the hardware selected for a particular fuel system 200 will function appropriately/effectively and does not result in any dangerous or inherently inaccurate fuel system configuration. Other rules include constraints on relative flow meter sizes. In an embodiment, the return flow meter 216 may not be larger than the supply flow meter 214. In an embodiment, the return flow rate may not be a value greater than the supply flow rate. In an embodiment, in the case of the fuel system 200, the inlet temperature 604 may not be higher than the outlet temperature 606. In an embodiment, the fluid density 602 may not exceed the density of the fluid allowed by the selected flow meter. These are merely examples of rules that are checked in step 706, and other rules are contemplated to be within the scope of this specification and claims. In an embodiment, some rules are used to provide flags or warnings to indicate potential, but not absolute, problems. These rules may simply warn of potential incompatibilities, but will still allow the system 400 to process such inputs 402.

In step 708, if the inputs 402 are compatible with each other and any other constraints, the system logic 408 calculates the outputs 410, such as system accuracy 412, 414. In this step, the system logic 408 may use any inputs, stored information, and/or constants to calculate any number of intermediate or final output values. An example of an intermediate value is the supply flow meter uncertainty. In an embodiment, the supply flow meter uncertainty is calculated according to equation (1): . Another example of an intermediate value is the return flow meter uncertainty. Outputs such as system accuracy 412, temperature-corrected system accuracy 414, and accuracy by the square root of the sum of squares are also calculated by the system logic 408 in this step. In an embodiment, the system accuracy 412, temperature-corrected system accuracy 414, and accuracy by the square root of the sum of squares are calculated using equations (3), (4), and (5), respectively.

In step 710, the system accuracy 412, 414 is stored in memory or a computer-readable storage medium along with any other output 410. These values may then be output in step 712. For example, output generally means informing a user of the calculated values via a display device 302, or printing the calculated values to a peripheral device such as a printer, or sending the calculated values to a user via email.

The present invention, as described above, provides various methods for calculating accuracy in a multi-vibration flow meter system using meters such as Coriolis flow meters. Although the various embodiments described above are directed to flow meters, and particularly Coriolis flow meters, it should be appreciated that the present invention should not be limited to Coriolis flow meters, but rather, the methods described herein can be utilized with respect to other types of flow meters, or other vibration sensors that lack some of the measurement capabilities of Coriolis flow meters.

The detailed description of the above embodiments is not an exhaustive description of all embodiments contemplated by the inventors to be within the scope of the present invention. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments may be variously combined or eliminated to create additional embodiments, and such additional embodiments fall within the scope and teachings of the present invention. It will also be apparent to those skilled in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the present invention.

Thus, although specific embodiments of the present invention and examples thereof are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the present invention, as will be appreciated by those skilled in the relevant art. The teachings provided herein are applicable to other vibration sensors, and not only to the embodiments described above and shown in the accompanying drawings. Accordingly, the scope of the present invention should be determined from the following claims.

Claims (23)

1. A method for determining the accuracy of a system, comprising the following steps: Input the hardware specifications of the supply flow meter into the computing device; Input the hardware specifications of the return flow meter into the computing device; Input the system parameters into the computing device; The system accuracy is calculated using system logic, wherein the system logic receives inputs based on the hardware specifications of the supply flow meter, the hardware specifications of the return flow meter, and the system parameters; The accuracy of the calculated system is stored in a computer-readable storage medium; and Output the system accuracy of the calculation. 2. The method for determining system accuracy according to claim 1, wherein the hardware specifications of the supply flow meter and the return flow meter both include basic accuracy values. 3. The method for determining system accuracy according to claim 1, wherein the hardware specifications of both the supply flow meter and the return flow meter include a zero-point offset value. 4. The method for determining system accuracy according to claim 1, wherein the hardware specifications of both the supply flow meter and the return flow meter include temperature drift values. 5. The method for determining system accuracy according to claim 1, wherein the hardware specifications of both the supply flow meter and the return flow meter include a maximum flow rate value. 6. The method for determining system accuracy according to claim 1, wherein the system parameters include a zero-point calibration temperature value. 7. The method for determining system accuracy according to claim 1, wherein the system parameters include fluid density. 8. The method for determining system accuracy according to claim 1, wherein the system parameters include inlet temperature and outlet temperature. 9. The method for determining system accuracy according to claim 1, characterized in that the step of calculating system accuracy using system logic includes the following steps: Calculate the supply flow meter uncertainty U _S , where, where: To address the temperature drift of the supply flow meter; The flow rate is the maximum supply flow rate. Inlet temperature; Zero-point calibration temperature; To account for the zero-point offset of the supply flow meter; To ensure the basic accuracy of the supply flow meter; and Supply flow rate conversion factor; Calculate the return flow meter uncertainty U_{_R}, where, where: To return the temperature drift of the flow meter; Maximum return flow rate; The outlet temperature; Zero-point calibration temperature; To return the zero-point offset of the flow meter; To ensure the basic accuracy of the return flow meter; and This is to return the flow rate conversion factor. 10. The method for determining system accuracy according to claim 9, wherein the step of calculating system accuracy using system logic includes the step of calculating the total differential measurement accuracy A _{Factory Zero} , where A _{Factory Zero =} . 11. The method for determining system accuracy according to claim 9, characterized in that the step of calculating system accuracy using system logic includes the step of calculating process temperature correction system accuracy A _Process , where A _Process = , and where _CFC is a fuel consumption conversion factor. 12. The method for determining system accuracy according to claim 1, characterized in that the method includes the step of providing a notification if at least one of the system parameters and hardware specifications is incompatible with at least one predetermined rule. 13. The method for determining system accuracy according to claim 1, characterized in that the method comprises the following steps: The system parameters input are used to generate suggested hardware specifications for the supply flow meter; and The system parameters input are used to generate recommended hardware specifications for the return flow meter. 14. A system (400) for configuring a metering system, comprising: At least two flow meters (214, 216); A computing device (300) configured to receive at least one input (402) and generate at least one output (410), wherein the at least one input (402) includes at least one flow meter hardware specification (404) and at least one system parameter (406); and System logic (408) configured with respect to the computing device (300) to calculate the at least one output (410), wherein the at least one output (410) includes at least one of system accuracy (412) and temperature-corrected system accuracy (414). 15. The system (400) for configuring a metering system according to claim 14, wherein the at least one hardware specification (404) includes a basic accuracy value (506). 16. The system (400) for configuring a metering system according to claim 14, wherein the at least one hardware specification (404) includes a zero-point offset value (508). 17. The system (400) for configuring a metering system according to claim 14, wherein the at least one hardware specification (404) includes a temperature drift value (510). 18. The system (400) for configuring a metering system according to claim 14, wherein the at least one hardware specification (404) includes a maximum flow rate value (512). 19. The system (400) for configuring a metering system according to claim 14, wherein the at least one system parameter (406) includes a zero-point calibration temperature value (600). 20. The system (400) for configuring a metering system according to claim 14, wherein the at least one system parameter (406) includes fluid density (602). 21. The system (400) for configuring a metering system according to claim 14, wherein the at least one system parameter (406) includes an inlet temperature (604) and an outlet temperature (606). 22. The system (400) for configuring a metering system according to claim 14, characterized in that the system accuracy (412) includes A _{Factory Zero} , where A _{Factory Zero} = , and wherein: ; To address the temperature drift of the supply flow meter; The flow rate is the maximum supply flow rate. Inlet temperature; Zero-point calibration temperature; To account for the zero-point offset of the supply flow meter; To ensure the basic accuracy of the supply flow meter; Supply flow rate conversion factor; ; To return the temperature drift of the flow meter; Maximum return flow rate; The outlet temperature; Zero-point calibration temperature; To return the zero-point offset of the flow meter; To ensure the basic accuracy of the return flow meter; and This is to return the flow rate conversion factor. 23. The system (400) for configuring a metering system according to claim 14, characterized in that the system accuracy (414) of the temperature correction includes A _process , where A _process = , and where: To account for the zero-point offset of the supply flow meter; To ensure the basic accuracy of the supply flow meter; Supply flow rate conversion factor; To return the zero-point offset of the flow meter; To ensure the basic accuracy of the flow meter; For the return flow rate conversion factor; and This is the fuel consumption conversion factor.